LOW BASIS WEIGHT NONWOVEN WEBS AND METHODS FOR MAKING SAME

Abstract

Low basis weight, for example less than 5 gsm, nonwoven webs, rolls thereof, and methods for making same are provided.

Claims

1. A low basis weight nonwoven web exhibiting a basis weight of less than 5 gsm, wherein the low basis weight nonwoven web comprises a plurality of hydroxyl polymer fibrous elements; wherein the hydroxyl polymer fibrous elements have an average fiber diameter of less than 4.5 microns as measured by the average fiber diameter method.

2. The low basis weight nonwoven web according to claim 1 wherein the low basis weight nonwoven web has a MD fail TEA greater than 13 g/in/per gsm.

3. The low basis weight nonwoven web according to claim 1 wherein the low basis weight nonwoven web exhibits a basis weight of less than 3 gsm.

4. The low basis weight nonwoven web according to claim 3 wherein the low basis weight nonwoven web exhibits a basis weight of less than 2 gsm.

5. The low basis weight nonwoven web according to claim 1 wherein the low basis weight nonwoven web exhibits a basis weight of greater than 0.25 gsm.

6. The low basis weight nonwoven web according to claim 5 wherein the low basis weight nonwoven web exhibits a basis weight of greater than 0.50 gsm.

7. The low basis weight nonwoven web according to claim 6 wherein the low basis weight nonwoven web exhibits a basis weight of greater than 0.75 gsm.

8. The low basis weight nonwoven web according to claim 7 wherein the low basis weight nonwoven web exhibits a basis weight of greater than 1 gsm.

9. The low basis weight nonwoven web according to claim 1 wherein the low basis weight nonwoven web exhibits a basis weight of greater than 0.25 gsm to less than 5 gsm.

10. The low basis weight nonwoven web according to claim 9 wherein the low basis weight nonwoven web exhibits a basis weight of greater than 0.50 gsm to less than 4 gsm.

11. The low basis weight nonwoven web according to claim 10 wherein the low basis weight nonwoven web exhibits a basis weight of greater than 0.75 gsm to less than 3 gsm.

12. The low basis weight nonwoven web according to claim 11 wherein the low basis weight nonwoven web exhibits a basis weight of from about 1 gsm to about 2 gsm.

13. The low basis weight nonwoven web according to claim 1 wherein the low basis weight nonwoven web exhibits a total dry tensile of greater than 75 g/in as measured according to the Tensile Test Method.

14. The low basis weight nonwoven web according to claim 13 wherein the low basis weight nonwoven web exhibits a total dry tensile of greater than 100 g/in as measured according to the Tensile Test Method.

15. The low basis weight nonwoven web according to claim 14 wherein the low basis weight nonwoven web exhibits a total dry tensile of greater than 150 g/in as measured according to the Tensile Test Method.

16. The low basis weight nonwoven web according to claim 15 wherein the low basis weight nonwoven web exhibits a total dry tensile strength of greater than 200 g/in as measured according to the Tensile Test Method.

17. The low basis weight nonwoven web according to claim 16 wherein the low basis weight nonwoven web exhibits a total dry tensile of greater than 300 g/in as measured according to the Tensile Test Method.

18. The low basis weight nonwoven web according to claim 17 wherein the low basis weight nonwoven web exhibits a total dry tensile of greater than 400 g/in as measured according to the Tensile Test Method.

19. The low basis weight nonwoven web according to claim 1 wherein the low basis weight nonwoven web exhibits a total dry tensile of less than 2000 g/in as measured according to the Tensile Test Method.

20. The low basis weight nonwoven web according to claim 19 wherein the low basis weight nonwoven web exhibits a total dry tensile of less than 1500 g/in as measured according to the Tensile Test Method.

21. A method for making a low basis weight nonwoven web, the method comprising the steps of: a. providing a hydroxyl polymer composition; b. spinning the hydroxyl polymer composition to form a plurality of hydroxyl polymer fibrous elements; c. collecting the plurality of hydroxyl polymer fibrous elements on a collection device such that a low basis weight nonwoven web that exhibits a basis weight of less than 5 gsm is formed.

22. The method according to claim 21 wherein the method further comprises the step of winding the low basis weight nonwoven web convolutely about itself such that a roll of low basis weight nonwoven web is formed.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0068] FIG. 1 is a schematic representation of an example of a method for making a low basis weight nonwoven web according to the present invention;

[0069] FIG. 2 is a schematic representation of another example of a method for making a low basis weight nonwoven web according to the present invention;

[0070] FIG. 3 is a schematic representation of yet another example of a method for making a low basis weight nonwoven web according to the present invention;

[0071] FIG. 4 is a side view representation of an example of a low basis weight nonwoven web according to the present invention;

[0072] FIG. 5 is a side view representation of another example of a low basis weight nonwoven web according to the present invention;

[0073] FIG. 6 is a top view representation of an example of a multi-row capillary meltblow die suitable for use in the methods of the present invention;

[0074] FIG. 7 is a schematic representation of the Roll Compressibility Test Method equipment and set-up; and

DETAILED DESCRIPTION OF THE INVENTION

[0075] Typically, melt blown nonwoven webs are not made at low basis weight, particularly less than 10 gsm, due to low tensile strength and/or low elongation at break. The low basis weight webs cannot support a load without falling apart or tearing, creating difficulties during web handling including sheet breaks, tears, and fold-overs. Thus, non-woven webs are typically confined to a minimum basis weight that can be used in consumer products. Surprisingly, if a nonwoven web is created from a material with sufficient elongation and strength properties and spun to very fine diameter filaments, less than 4.5 microns as measured by the average fiber diameter method, a very low basis weight product can be formed that can support a load and not fall apart upon web handling. Particularly, a PVOH web of around 1.0 to 2.0 gsm, can be spun into a parent roll, unwound, and then combined with a paper structure without web breaks. It is important that very fine filaments, less than 4.5 microns in diameter are formed which increases the number of fiber-to-fiber contacts for a given basis weight. This will also increase the tensile strength, fail stretch, and fail total energy absorbed (TEA) per unit basis weight of the web which is critical to winding and unwinding a nonwoven layer at 1-2 gsm basis weight. Particularly, a MD fail TEA greater than 12 g/in per gsm is generated in the low basis weight web. There are commercially available PVOH nonwovens, however the fiber diameters are considerably larger, roughly 20 microns which means fewer fiber-to-fiber contacts for a given basis weight, and consequently the resulting tensile properties and fail TEA per unit basis weight are not sufficient to withstand the forces of the winding and unwinding steps.

Definitions

[0076] Nonwoven web as used herein means an orderly arrangement of a plurality of non-naturally occurring fibrous elements, for example non-naturally occurring filaments and/or non-naturally occurring fibers, in a fibrous assembly, typically in sheet and/or fibrous structure form. In embodiments, the fibrous elements are inter-entangled. In embodiments, the fibrous elements are bonded together, for example chemically bonded, thermally bonded, mechanically bonded and/or ultrasonically bonded together to provide the nonwoven web with sufficient integrity for its intended uses. In embodiments, the non-naturally occurring fibrous elements comprise a plurality of spun filaments, for example a plurality of spun hydroxyl polymer filaments such as spun polyvinyl alcohol filaments and/or spun cellulose filaments, for example spun regenerated cellulose filaments such as lyocell filaments and/or rayon filaments, and/or a plurality of fibers, which include, but are not limited to, fibers cut from spun filaments, for example staple fibers, such as polyvinyl alcohol fibers and/or regenerated cellulose fibers, such as lyocell fibers and/or rayon fibers.

[0077] Low basis weight nonwoven web as used herein means a nonwoven web that exhibits a basis weight of less than 5 gsm and/or less than 4 gsm and/or less than 3 gsm and/or less than 2 gsm to greater than 0.25 gsm and/or to greater than 0.5 gsm and/or to greater than 0.75 gsm and/or to at least 1 gsm as measured according to the Basis Weight Test Method described herein.

[0078] Non-naturally occurring as used herein, for example, with respect to a non-naturally occurring fibrous element(s) means that the fibrous element, for example filament and/or fiber is not found in nature in that form. In other words, some chemical processing of materials occurred in order to obtain the non-naturally occurring fibrous element, for example filament and/or fiber. For example, a wood pulp fiber is a naturally occurring fiber, however, if the wood pulp fiber is chemically processed, such as via a lyocell-type process, a solution of cellulose is formed. The solution of cellulose may then be spun into a fiber. Accordingly, this spun fibrous element, for example filament and/or fiber, for example lyocell filament and/or fiber and/or rayon filament and/or fiber, would be considered a non-naturally occurring fiber since such a fibrous element is not directly obtainable from nature, rather it was made by a human process.

[0079] Fibrous element as used herein means an elongate particulate having a length greatly exceeding its average fiber diameter, i.e. a length to average fiber diameter ratio of at least about least about 10 and/or at least about 100 and/or at least about 1000 and/or up to 5000. A fibrous element may be a filament or a fiber. In embodiments, the fibrous element is a single fibrous element rather than a yarn comprising a plurality of fibrous elements.

[0080] The fibrous elements of the present invention may be spun from polymer compositions via suitable spinning operations, such as meltblowing and/or spunbonding.

[0081] The fibrous elements, for example filaments and/or fibers, of the present invention may be monocomponent and/or multicomponent. For example, the fibrous elements may comprise bicomponent fibers and/or bicomponent filaments. The bicomponent fibers and/or filaments may be in any form, such as side-by-side, core and sheath, islands-in-the-sea and the like. In embodiments, the fibrous elements may comprise monocomponent fibers and/or monocomponent filaments.

[0082] Filament as used herein means an elongate particulate as described above that exhibits a length of greater than or equal to 5.08 cm (2 in.) and/or greater than or equal to 7.62 cm (3 in.) and/or greater than or equal to 10.16 cm (4 in.) and/or greater than or equal to 15.24 cm (6 in.). The filament may exhibit a length to average fiber diameter ratio of at least about 100 and/or at least about 1000 and/or up to 5000.

[0083] Filaments are typically considered continuous or substantially continuous in nature. Filaments are relatively longer than fibers. Non-limiting examples of filaments include meltblown and/or spunbond filaments. Non-limiting examples of polymers that can be spun into filaments include hydroxyl polymers such as natural polymers, such as starch, starch derivatives, cellulose, such as rayon and/or lyocell, and cellulose derivatives, hemicellulose, hemicellulose derivatives, and synthetic hydroxyl polymers including, but not limited to polyvinyl alcohol and/or polyvinyl alcohol derivatives, and other synthetic polymers, such as biodegradable polymers and/or compostable polymers such as polylactic acid, polyhydroxyalkanoate, polyesteramide, and polycaprolactone.

[0084] Fiber as used herein means an elongate particulate as described above that exhibits a length of less than 5.08 cm (2 in.) and/or less than 3.81 cm (1.5 in.) and/or less than 2.54 cm (1 in.). The fiber may exhibit a length to average fiber diameter ratio of less than 100 and/or less than about 50 and/or less than about 25 and/or about 10.

[0085] Fibers are typically considered discontinuous in nature. Non-limiting examples of fibers include pulp fibers, such as wood pulp fibers, and synthetic staple fibers such as polyvinyl alcohol fibers and regenerated cellulose fibers, for example rayon fibers and lyocell fibers.

[0086] Synthetic staple fibers may be produced by spinning a filament tow and then cutting the filament tow into segments (fibers) of less than 5.08 cm (2 in.) thus producing synthetic staple fibers.

[0087] Basis Weight as used herein is the weight per unit area of a sample reported in lbs/3000 ft.sup.2 or g/m.sup.2 (gsm) and is measured according to the Basis Weight Test Method described herein.

[0088] Machine Direction or MD as used herein means the direction parallel to the flow of the base fibrous structure and/or low basis weight nonwoven web through the fibrous structure and/or nonwoven web making machine.

[0089] Cross Machine Direction or CD as used herein means the direction parallel to the width of the fibrous structure and/or nonwoven web making machine and perpendicular to the MD.

[0090] Ply as used herein means an individual, integral fibrous structure.

[0091] Plies as used herein means two or more individual, integral fibrous structures disposed in a substantially contiguous, face-to-face relationship with one another, forming a multi-ply fibrous structure and/or multi-ply toilet tissue. It is also contemplated that an individual, integral fibrous structure can effectively form a multi-ply fibrous structure, for example, by being folded on itself.

[0092] Hydroxyl polymer as used herein includes any hydroxyl-containing polymer that can be incorporated into a fibrous element of the present invention. In embodiments, the hydroxyl polymer of the present invention includes greater than 10% and/or greater than 20% and/or greater than 25% by weight hydroxyl moieties. In another example, the hydroxyl within the hydroxyl-containing polymer is not part of a larger functional group such as a carboxylic acid group.

[0093] Chemically different as used herein with respect to two hydroxyl polymers means that the hydroxyl polymers are at least different structurally, and/or at least different in properties and/or at least different in classes of chemicals, for example polysaccharides, such as starch, versus non-polysaccharides, such as polyvinyl alcohol, and/or at least different in their respective solubility parameters.

[0094] Non-thermoplastic as used herein means, with respect to a material, such as a fibrous element as a whole and/or a polymer within a fibrous element, that the fibrous element and/or polymer exhibits no melting point and/or softening point, which allows it to flow under pressure, in the absence of a plasticizer, such as water, glycerin, sorbitol, urea and the like.

[0095] Non-cellulose-containing as used herein means that less than 5% and/or less than 3% and/or less than 1% and/or less than 0.1% and/or 0% by weight of cellulose polymer, cellulose derivative polymer and/or cellulose copolymer is present in fibrous element. In embodiments, non-cellulose-containing means that less than 5% and/or less than 3% and/or less than 1% and/or less than 0.1% and/or 0% by weight of cellulose polymer is present in fibrous element.

[0096] Polymer composition as used herein means a composition comprising a solvent, for example water and/or a non-water solvent such as those used in regenerated cellulose processing, and a hydroxyl polymer, for example polyvinyl alcohol and/or a polysaccharide, for example starch and/or starch derivative and/or cellulose and/or cellulose derivative.

[0097] Average Fiber Diameter as used herein, with respect to one or more fibrous elements, for example one or more filaments and/or one or more fibers, is measured according to the Average Fiber Diameter Test Method described herein. In embodiments, one or more fibrous elements, for example one or more filaments and/or fibers, of the present invention exhibit an average fiber diameter of less than 50 m and/or less than 25 m and/or less than 20 m and/or less than 15 m and/or less than 10 m and/or less than 6 m and/or greater than 1 m and/or greater than 3 m as measured according to the Average Fiber Diameter Test Method described herein.

[0098] As used herein, the articles a and an when used herein, for example, an anionic surfactant or a fiber is understood to mean one or more of the material that is claimed and/or described.

[0099] As used herein, the term embodiments is understood to include one or more embodiments, such as a single embodiment or multiple embodiments.

[0100] All percentages and ratios are calculated by weight unless otherwise indicated. All percentages and ratios are calculated based on the total composition unless otherwise indicated.

[0101] Unless otherwise noted, all component or composition levels are in reference to the active level of that component or composition, and are exclusive of impurities, for example, residual solvents or by-products, which may be present in commercially available sources.

Low Basis Weight Nonwoven Web

[0102] As shown in FIGS. 1 to 5, in embodiments of the present invention, the low basis weight nonwoven web 14 comprises a plurality of fibrous elements, for example filaments 28 as shown in FIGS. 1 and 4 and/or fibers 26 as shown in FIGS. 2, 3 and 5.

[0103] As shown in FIG. 4, in embodiments of the present invention, the low basis weight nonwoven web 14 comprises a plurality of filaments 28. The filaments 28 may comprise hydroxyl polymer filaments, such as water-soluble hydroxyl polymer filaments, for example polyvinyl alcohol filaments. In embodiments, the plurality of filaments 28 are inter-entangled. In another example, the plurality of filaments 28 are monocomponent filaments. In still another example, the plurality of filaments 28 comprises polyvinyl alcohol filaments.

[0104] In another example of the present invention, the low basis weight nonwoven web 14 comprises a plurality of filaments 28, for example hydroxyl polymer filaments, such as water-soluble hydroxyl polymer filaments, for example polyvinyl alcohol filaments, such that the low basis weight nonwoven web 14 exhibits a basis weight of less than 5 gsm and/or less than 4 gsm and/or less than 3 gsm and/or less than 2 gsm to greater than 0.25 gsm and/or to greater than 0.5 gsm and/or to greater than 0.75 gsm and/or to at least 1 gsm as measured according to the Basis Weight Test Method described herein.

[0105] In another example of the present invention, the low basis weight nonwoven web 14 comprises a plurality of filaments 28, for example hydroxyl polymer filaments, such as water-soluble hydroxyl polymer filaments, for example polyvinyl alcohol filaments, such that the low basis weight nonwoven web 14 exhibits a basis weight of less than 5 gsm and/or less than 4 gsm and/or less than 3 gsm and/or less than 2 gsm to greater than 0.25 gsm and/or to greater than 0.5 gsm and/or to greater than 0.75 gsm and/or to at least 1 gsm as measured according to the Basis Weight Test Method described herein, and wherein the plurality of filaments 28 exhibit an average fiber diameter of less than 4.5 microns and/or less than 4.0 microns and/or less than 3.5 microns and/or less than 3.0 microns and/or to greater than 0.5 m and/or to greater than 0.75 m as measured according to the Average Fiber Diameter Test Method described herein.

[0106] In another example of the present invention, the low basis weight nonwoven web 14 comprises a plurality of filaments 28, for example hydroxyl polymer filaments, such as water-soluble hydroxyl polymer filaments, for example polyvinyl alcohol filaments, such that the low basis weight nonwoven web 14 exhibits a basis weight of less than 5 gsm and/or less than 4 gsm and/or less than 3 gsm and/or less than 2 gsm to greater than 0.25 gsm and/or to greater than 0.5 gsm and/or to greater than 0.75 gsm and/or to at least 1 gsm as measured according to the Basis Weight Test Method described herein and a fail total energy absorption (TEA) of at least 12 g/in/gsm and/or at least 14 g/in/gsm and/or at least 16 g/in/gsm as measured according to the Tensile Test Method described herein.

[0107] In another example of the present invention, the low basis weight nonwoven web 14 comprises a plurality of filaments 28, for example hydroxyl polymer filaments, such as water-soluble hydroxyl polymer filaments, for example polyvinyl alcohol filaments, such that the low basis weight nonwoven web 14 exhibits a basis weight of less than 5 gsm and/or less than 4 gsm and/or less than 3 gsm and/or less than 2 gsm to greater than 0.25 gsm and/or to greater than 0.5 gsm and/or to greater than 0.75 gsm and/or to at least 1 gsm as measured according to the Basis Weight Test Method described herein and a total dry tensile of greater than 75 g/in and/or greater than 100 g/in and/or greater than 150 g/in and/or greater than 200 g/in and/or greater than 300 g/in and/or greater than 400 g/in and/or greater than 500 g/in to less than 2000 g/in and/or to less than 1500 g/in and/or to less than 1000 g/in as measured according to the Tensile Test Method described herein.

[0108] In yet another example of the present invention, the low basis weight nonwoven web 14 comprises a plurality of filaments 28, for example hydroxyl polymer filaments, such as water-soluble hydroxyl polymer filaments, for example polyvinyl alcohol filaments, such that the low basis weight nonwoven web 14 exhibits a basis weight of less than 5 gsm and/or less than 4 gsm and/or less than 3 gsm and/or less than 2 gsm to greater than 0.25 gsm and/or to greater than 0.5 gsm and/or to greater than 0.75 gsm and/or to at least 1 gsm as measured according to the Basis Weight Test Method described herein and a total dry tensile of less than 2000 g/in as measured according to the Tensile Test Method described herein.

[0109] In another example of the present invention, the low basis weight nonwoven web 14 comprises a plurality of filaments 28, for example hydroxyl polymer filaments, such as water-soluble hydroxyl polymer filaments, for example polyvinyl alcohol filaments, such that the low basis weight nonwoven web 14 exhibits a basis weight of less than 5 gsm and/or less than 4 gsm and/or less than 3 gsm and/or less than 2 gsm to greater than 0.25 gsm and/or to greater than 0.5 gsm and/or to greater than 0.75 gsm and/or to at least 1 gsm as measured according to the Basis Weight Test Method described herein and a TS7 of less than 20 dB V.sup.2 rms and/or less than 15 dB V.sup.2 rms and/or less than 12 dB V.sup.2 rms and/or less than 10 dB V.sup.2 rms and/or less than 8 dB V.sup.2 rms and/or less than 6 dB V.sup.2 rms and/or less than 4 dB V.sup.2 rms as measured according to the Emtec Test Method described herein.

[0110] In still another example of the present invention, the low basis weight nonwoven web 14 comprises a plurality of filaments 28, for example hydroxyl polymer filaments, such as water-soluble hydroxyl polymer filaments, for example polyvinyl alcohol filaments, such that the low basis weight nonwoven web 14 exhibits a basis weight of less than 5 gsm and/or less than 4 gsm and/or less than 3 gsm and/or less than 2 gsm to greater than 0.25 gsm and/or to greater than 0.5 gsm and/or to greater than 0.75 gsm and/or to at least 1 gsm as measured according to the Basis Weight Test Method described herein and a Force Variability Value of less than 1.40 and/or less than 1.25 as measured according to the Glide on Skin Test Method described herein.

[0111] In another example of the present invention, the low basis weight nonwoven web 14 comprises a plurality of filaments 28, for example hydroxyl polymer filaments, such as water-soluble hydroxyl polymer filaments, for example polyvinyl alcohol filaments, such that the low basis weight nonwoven web 14 exhibits a basis weight of less than 5 gsm and/or less than 4 gsm and/or less than 3 gsm and/or less than 2 gsm to greater than 0.25 gsm and/or to greater than 0.5 gsm and/or to greater than 0.75 gsm and/or to at least 1 gsm as measured according to the Basis Weight Test Method described herein and a Force to Drag Value of less than 100 and/or less than 90 as measured according to the Glide on Skin Test Method described herein.

[0112] As shown in FIG. 5, in embodiments of the present invention, the low basis weight nonwoven web 14 comprises a plurality of fibers 26. The fibers 26 may comprise a plurality of non-naturally occurring hydroxyl polymer fibers, for example a plurality of non-naturally occurring non-water soluble hydroxyl polymer fibers, such as a plurality of regenerated cellulose fibers, for example a plurality of rayon fibers and/or lyocell fibers hydroxyl polymer fibers. In embodiments, the fibers 26 may comprise polyvinyl alcohol fibers.

[0113] In another example of the present invention, the low basis weight nonwoven web comprises a plurality of fibers 26. The fibers 26 may comprise a plurality of non-naturally occurring hydroxyl polymer fibers, for example a plurality of non-naturally occurring non-water soluble hydroxyl polymer fibers, such as a plurality of regenerated cellulose fibers, for example a plurality of rayon fibers and/or lyocell fibers hydroxyl polymer fibers, such that the low basis weight nonwoven web 14 exhibits a basis weight of less than 5 gsm and/or less than 4 gsm and/or less than 3 gsm and/or less than 2 gsm to greater than 0.25 gsm and/or to greater than 0.5 gsm and/or to greater than 0.75 gsm and/or to at least 1 gsm as measured according to the Basis Weight Test Method described herein.

[0114] In another example of the present invention, the low basis weight nonwoven web 14 comprises a plurality of fibers 26. The fibers 26 may comprise a plurality of non-naturally occurring hydroxyl polymer fibers, for example a plurality of non-naturally occurring non-water soluble hydroxyl polymer fibers, such as a plurality of regenerated cellulose fibers, for example a plurality of rayon fibers and/or lyocell fibers hydroxyl polymer fibers, such that the low basis weight nonwoven web 14 exhibits a basis weight of less than 5 gsm and/or less than 4 gsm and/or less than 3 gsm and/or less than 2 gsm to greater than 0.25 gsm and/or to greater than 0.5 gsm and/or to greater than 0.75 gsm and/or to at least 1 gsm as measured according to the Basis Weight Test Method described herein, and wherein the plurality of fibers 26 exhibit an average fiber diameter of less than 2 m and/or less than 1.75 m and/or less than 1.5 m to greater than 0.5 m and/or to greater than 0.75 m as measured according to the Average Fiber Diameter Test Method described herein.

[0115] comprises a plurality of fibers 26. The fibers 26 may comprise a plurality of non-naturally occurring hydroxyl polymer fibers, for example a plurality of non-naturally occurring non-water soluble hydroxyl polymer fibers, such as a plurality of regenerated cellulose fibers, for example a plurality of rayon fibers and/or lyocell fibers hydroxyl polymer fibers, such that the low basis weight nonwoven web 14 exhibits a basis weight of less than 5 gsm and/or less than 4 gsm and/or less than 3 gsm and/or less than 2 gsm to greater than 0.25 gsm and/or to greater than 0.5 gsm and/or to greater than 0.75 gsm and/or to at least 1 gsm as measured according to the Basis Weight Test Method described herein and a fail total energy absorption (TEA) of at least 12 g/in/gsm and/or at least 14 g/in/gsm and/or at least 16 g/in/gsm as measured according to the Tensile Test Method described herein.

[0116] In another example of the present invention, the low basis weight nonwoven web 14 comprises a plurality of fibers. The fibers 26 may comprise a plurality of non-naturally occurring hydroxyl polymer fibers, for example a plurality of non-naturally occurring non-water soluble hydroxyl polymer fibers, such as a plurality of regenerated cellulose fibers, for example a plurality of rayon fibers and/or lyocell fibers hydroxyl polymer fibers, such that the low basis weight nonwoven web 14 exhibits a basis weight of less than 5 gsm and/or less than 4 gsm and/or less than 3 gsm and/or less than 2 gsm to greater than 0.25 gsm and/or to greater than 0.5 gsm and/or to greater than 0.75 gsm and/or to at least 1 gsm as measured according to the Basis Weight Test Method described herein and a total dry tensile of greater than 75 g/in and/or greater than 100 g/in and/or greater than 150 g/in and/or greater than 200 g/in and/or greater than 300 g/in and/or greater than 400 g/in and/or greater than 500 g/in to less than 2000 g/in and/or to less than 1500 g/in and/or to less than 1000 g/in as measured according to the Tensile Test Method described herein.

[0117] In yet another example of the present invention, the low basis weight nonwoven web 14 comprises a plurality of fibers 26. The fibers 26 may comprise a plurality of non-naturally occurring hydroxyl polymer fibers, for example a plurality of non-naturally occurring non-water soluble hydroxyl polymer fibers, such as a plurality of regenerated cellulose fibers, for example a plurality of rayon fibers and/or lyocell fibers hydroxyl polymer fibers, such that the low basis weight nonwoven web 14 exhibits a basis weight of less than 5 gsm and/or less than 4 gsm and/or less than 3 gsm and/or less than 2 gsm to greater than 0.25 gsm and/or to greater than 0.5 gsm and/or to greater than 0.75 gsm and/or to at least 1 gsm as measured according to the Basis Weight Test Method described herein and a total dry tensile of less than 2000 g/in as measured according to the Tensile Test Method described herein.

[0118] comprises a plurality of fibers 26. The fibers 26 may comprise a plurality of non-naturally occurring hydroxyl polymer fibers, for example a plurality of non-naturally occurring non-water soluble hydroxyl polymer fibers, such as a plurality of regenerated cellulose fibers, for example a plurality of rayon fibers and/or lyocell fibers hydroxyl polymer fibers, such that the low basis weight nonwoven web 14 exhibits a basis weight of less than 5 gsm and/or less than 4 gsm and/or less than 3 gsm and/or less than 2 gsm to greater than 0.25 gsm and/or to greater than 0.5 gsm and/or to greater than 0.75 gsm and/or to at least 1 gsm as measured according to the Basis Weight Test Method described herein and a TS7 of less than 20 dB V.sup.2 rms and/or less than 15 dB V.sup.2 rms and/or less than 12 dB V.sup.2 rms and/or less than 10 dB V.sup.2 rms and/or less than 8 dB V.sup.2 rms and/or less than 6 dB V.sup.2 rms and/or less than 4 dB V.sup.2 rms as measured according to the Emtec Test Method described herein.

[0119] In still another example of the present invention, the low basis weight nonwoven web 14 comprises a plurality of fibers 26. The fibers 26 may comprise a plurality of non-naturally occurring hydroxyl polymer fibers, for example a plurality of non-naturally occurring non-water soluble hydroxyl polymer fibers, such as a plurality of regenerated cellulose fibers, for example a plurality of rayon fibers and/or lyocell fibers hydroxyl polymer fibers, such that the low basis weight nonwoven web 14 exhibits a basis weight of less than 5 gsm and/or less than 4 gsm and/or less than 3 gsm and/or less than 2 gsm to greater than 0.25 gsm and/or to greater than 0.5 gsm and/or to greater than 0.75 gsm and/or to at least 1 gsm as measured according to the Basis Weight Test Method described herein and a Force Variability Value of less than 1.40 and/or less than 1.25 as measured according to the Glide on Skin Test Method described herein.

[0120] In another example of the present invention, the low basis weight nonwoven web 14 comprises a plurality of fibers 26. The fibers 26 may comprise a plurality of non-naturally occurring hydroxyl polymer fibers, for example a plurality of non-naturally occurring non-water soluble hydroxyl polymer fibers, such as a plurality of regenerated cellulose fibers, for example a plurality of rayon fibers and/or lyocell fibers hydroxyl polymer fibers, such that the low basis weight nonwoven web 14 exhibits a basis weight of less than 5 gsm and/or less than 4 gsm and/or less than 3 gsm and/or less than 2 gsm to greater than 0.25 gsm and/or to greater than 0.5 gsm and/or to greater than 0.75 gsm and/or to at least 1 gsm as measured according to the Basis Weight Test Method described herein and a Force to Drag Value of less than 100 and/or less than 90 as measured according to the Glide on Skin Test Method described herein.

[0121] In embodiments, the fibrous elements of the low basis weight nonwoven web 14 of the present invention may comprise a hydroxyl polymer, which may be a polysaccharide, such as a polysaccharide selected from the group consisting of: starch, starch derivatives, cellulose, cellulose derivatives, hemicellulose, hemicellulose derivatives, and mixtures thereof, more specifically cellulose, for example regenerated cellulose fibers such as lyocell and/or rayon.

[0122] In another example, the fibrous elements of the low basis weight nonwoven web 14 of the present invention may comprise a hydroxyl polymer comprising polyvinyl alcohol, for example polyvinyl alcohol filaments.

[0123] In still another example, the fibrous elements of the low basis weight nonwoven web 14 of the present invention may comprise two or more hydroxyl polymers selected from the group consisting of: polyvinyl alcohol, polysaccharides, such as polysaccharides selected from the group consisting of: starch, starch derivatives, cellulose derivatives, hemicellulose, and hemicellulose derivatives, and mixtures thereof, for example filaments comprising both polyvinyl alcohol and a polysaccharide selected from the group consisting of: starch, starch derivatives, cellulose derivatives, hemicellulose, and hemicellulose derivatives, and mixtures thereof, and/or both polyvinyl alcohol filaments and polysaccharide filaments, for example starch filaments.

[0124] In even another example, the fibrous elements of the low basis weight nonwoven web 14 of the present invention may comprise two or more different types of fibrous elements, for example filaments 28 and fibers 26.

[0125] In yet another example, the fibrous elements of the low basis weight nonwoven web 14 of the present invention may comprise one or more fibers 26, for example cellulose fibers, such as regenerated cellulose fibers, for example lyocell fibers and/or rayon fibers.

[0126] In embodiments, the low basis weight nonwoven web 14 of the present invention comprises polyvinyl alcohol filaments, for example greater than 50% and/or greater than 60% and/or greater than 70% and/or greater than 80% and/or greater than 90% and/or greater than 95% and/or greater than 99% to 100% by weight of polyvinyl alcohol filaments.

[0127] In embodiments, the low basis weight nonwoven web 14 of the present invention comprises cellulose fibers, for example regenerated cellulose fibers, such as lyocell fibers and/or rayon fibers, for example greater than 50% and/or greater than 60% and/or greater than 70% and/or greater than 80% and/or greater than 90% and/or greater than 95% and/or greater than 99% to 100% by weight of the cellulose fibers.

[0128] In embodiments, the low basis weight nonwoven web 14 of the present invention comprises water-soluble fibrous elements, for example water-soluble filaments such as polyvinyl alcohol filaments and/or non-cellulose containing filaments, such as starch and/or starch derivative filaments, for example greater than 50% and/or greater than 60% and/or greater than 70% and/or greater than 80% and/or greater than 90% and/or greater than 95% and/or greater than 99% to 100% by weight of water-soluble filaments.

[0129] In embodiments, the low basis weight nonwoven web 14 of the present invention comprises water-insoluble fibrous elements, for example water-insoluble fibers such as cellulose fibers, for example greater than 50% and/or greater than 60% and/or greater than 70% and/or greater than 80% and/or greater than 90% and/or greater than 95% and/or greater than 99% to 100% by weight of water-insoluble fibers.

[0130] In embodiments, the low basis weight nonwoven web 14 of the present invention comprises non-thermoplastic polymer fibrous elements, for example non-thermoplastic polyvinyl alcohol filaments and/or non-thermoplastic polysaccharide filaments and/or non-thermoplastic polyvinyl alcohol fibers and/or non-thermoplastic polysaccharide fibers, such as lyocell fibers and/or rayon fibers.

[0131] In embodiments, the fibrous elements of the low basis weight nonwoven web 14 may be produced from a polymer composition, for example a hydroxyl polymer composition such as an aqueous hydroxyl polymer composition, comprising a hydroxyl polymer, such as an uncrosslinked starch for example a dent corn starch, an acid-thinned starch, a waxy starch, and/or a starch derivative such as an ethoxylated starch, and/or polyvinyl alcohol, and optionally a crosslinking system comprising a crosslinking agent, such as an imidazolidinone, and water. The hydroxyl polymer may exhibit a weight average molecular weight in the range of 50,000 g/mol to 40,000,000 g/mol as measured according to the Weight Average Molecular Weight Test Method described herein. In embodiments, the crosslinking agent comprises less than 2% and/or less than 1.8% and/or less than 1.5% and/or less than 1.25% and/or 0% and/or about 0.25% and/or about 0.50% by weight of a base, for example triethanolamine.

[0132] The fibrous elements, for example filaments 28 and/or fibers 26 of the low basis weight nonwoven web 14 may exhibit an average fiber diameter of less than 50 m and/or less than 25 m and/or less than 20 m and/or less than 15 m and/or less than 10 m and/or greater than 1 m and/or greater than 3 m and/or from about 3-10 m and/or from about 3-8 m and/or from about 5-7 m as measured according to the Average Fiber Diameter Test Method described herein. When present, the fibrous elements, for example polyvinyl alcohol filaments may exhibit smaller average fiber diameters, for example from about 1 to about 3 m, than the polysaccharide filaments.

[0133] As mentioned previously, the fibrous elements, for example filaments 28 of the present invention may be produced from spinning a polymer composition. The polymer composition may have a temperature of from about 50 C. to about 100 C. and/or from about 65 C. to about 95 C. and/or from about 70 C. to about 90 C. when spinning fibrous elements, for example filaments 28 from the polymer composition that produce the fibrous elements, for example filaments 28 of the present invention.

[0134] The fibrous elements, for example filaments 28, such as polyvinyl alcohol filaments of the present invention may be attenuated during the spinning process to average fiber diameters of less than 2 m and/or less than 1.5 and/or less than 1 and/or less than 0.5 m average fiber diameter fibrous elements (filaments and/or fibers), with high humidity air streams (air jets), for example saturated air stream(s) of a flowrate of less than 1.5 and/or less than 1.25 and/or less than 1.0 water column, that result in the fibrous elements bonding more upon forming of the low basis weight nonwoven web 14.

[0135] In embodiments, the polymer composition of the present invention may comprise from about 30% and/or from about 40% and/or from about 45% and/or from about 50% to about 75% and/or to about 80% and/or to about 85% and/or to about 90% and/or to about 95% and/or to about 99.5% by weight of the polymer composition of a fibrous element-forming polymer, such as a hydroxyl polymer. The fibrous element-forming polymer, such as a hydroxyl polymer, may have a weight average molecular weight greater than 100,000 g/mol.

Hydroxyl Polymer

[0136] Non-limiting examples of suitable hydroxyl polymers include polyvinyl alcohol, polysaccharides, and mixtures thereof.

a. Polyvinyl Alcohol

[0137] Non-limiting examples of suitable polyvinyl alcohols, also referred to herein as vinyl acetate-vinyl alcohol copolymers, include vinyl acetate-vinyl alcohol copolymers that exhibit various degrees of hydrolysis, for example extremely high hydrolysis vinyl acetate-vinyl alcohol copolymers (average degree of at least 95 mol % and/or at least 97 mol % and/or at least 98 mol % and/or at least 99 mol % alcohol units (commonly referred to as % hydrolyzed), an example of which is Poval10-98 (98% hydrolyzed, Mw 50,000 g/mol) commercially available from Kuraray, high hydrolysis vinyl acetate-vinyl alcohol copolymers (average degree of at least 87 mol % and/or at least 89 mol % and/or at least 90 mol % to less than 95 mol % alcohol units, example of which is Selvol 523 (87-89% hydrolyzed, Mw 100,000 g/mol) commercially available from Sekisui Specialty Chemicals, and low hydrolysis vinyl acetate-vinyl alcohol copolymers (average degree of not more than 84 mol % and/or less than 84 mol % and/or less than 82 mol % and/or at least 99 mol % alcohol units.

[0138] As used herein, vinyl acetate-vinyl alcohol copolymer refers to a polymer of the following structure (I):

##STR00001##

In structure (I), m and n are integers such that the copolymer has the degree of polymerization and percent alcohol characteristics described herein. For purposes of clarity, this use of the term copolymer is intended to convey that the partially hydrolyzed polyvinyl acetate of the present invention comprises vinyl alcohol and vinyl acetate units. As discussed below, the copolymer is routinely prepared by polymerizing vinyl acetate monomer followed by hydrolysis of some of the acetate groups to alcohol groups, as opposed to polymerization of vinyl acetate and vinyl alcohol monomer units (due in-part to the instability of vinyl alcohol).

[0139] The degree of polymerization (weight average molecular weight) of the fibrous element-forming polymer, for example the vinyl acetate-vinyl alcohol copolymer, is measured using gel permeation chromatography (GPC). This form of chromatography utilizes size exclusion. Separation occurs through a column packed with porous beads. Smaller analytes spend more time in the pores and thus pass through the column more slowly. A detector measures the amount of polymer in the elution solvent as it is eluted. Reference herein to the molecular weight of the copolymer is weighted average molecular weight (Mw). The Mw of the fibrous element-forming polymer, for example the vinyl acetate-vinyl alcohol copolymer, can vary widely, but in embodiments the fibrous element-forming polymer, for example vinyl acetate-vinyl alcohol copolymer, exhibits a Mw of greater than 10,000 g/mol and/or from about 20,000 g/mol to about 500,000 g/mol, in another example from about 40,000 g/mol to about 400,000 g/mol, in yet another example from about 60,000 g/mol to about 300,000 g/mol, and in still another example from about 70,000 g/mol to about 200,000 g/mol.

[0140] In embodiments, the fibrous elements of the present invention can be prepared by combining two or more vinyl acetate-vinyl alcohol copolymers described herein, wherein the vinyl acetate-vinyl alcohol copolymers differ with respect to either or both of their degree of polymerization and/or their degree of hydrolysis.

[0141] The benefits identified can be achieved by using one vinyl acetate-vinyl alcohol copolymer described herein, or it is possible to use two distinct vinyl acetate-vinyl alcohol copolymers.

[0142] The vinyl acetate-vinyl alcohol copolymers useful in the present invention are readily prepared using well known chemistry. One such method is the hydrolysis of a starting polyvinyl ester (polyvinyl acetate; formed via polymerization of vinyl acetate monomer units) of the desired degree of polymerization with absolute alcohols (e.g., methanol) in the presence of catalytic amounts of alkali (e.g., sodium methoxide). In the hydrolysis of polyvinyl acetate to vinyl acetate-vinyl alcohol copolymer, products with different alcohol group contents can be obtained depending on production conditions. Hydrolysis conditions influence the structure of the vinyl acetate-vinyl alcohol copolymer formed. By varying catalyst concentration, reaction temperature, and the reaction time, the content of residual acetyl groups (i.e., unhydrolyzed acetyl groups) can be adjusted routinely. See, for example, Polyvinyl Compounds, Others, Ullmann's Encyclopedia of Industrial Chemistry, Vol. 29, p. 605-609 (2000). Vinyl acetate-vinyl alcohol copolymers are also available commercially, e.g. from Kuraray Europe GmbH.

b. Cellulose

[0143] Non-limiting examples of cellulose polymers suitable for use in the fibrous elements of the present invention include regenerated cellulose, for example lyocell and/or rayon.

[0144] In embodiments, lyocell is made by dissolving wood pulp in an amine oxide solution. The viscous cellulose solution that results is then extruded into a dilute solution of amine oxide, which precipitates the regenerated cellulose, in this case lyocell, as a fibrous element, for example filament, which may then be cut into fibers, for example staple fibers.

[0145] In embodiments, lyocell is a regenerated cellulose material made by dissolving cellulose, for example cellulose in the form of wood pulp fibers, in a mixture of N-methylmorpholine-Noxide (NMMO) and water and extruding the resulting solution into a regenerating bath, usually water. Other solvents that may be used are other amine oxides, ionic liquids, mixtures of ionic liquids and water, and mixtures of ionic liquids and organic solvents. Lyocell is a generic term for a fiber composed of cellulose precipitated from an organic solution in which no substitution of hydroxyl groups takes place and no chemical intermediates are formed. Several manufacturers presently produce lyocell fibers. For example, Lenzing, Ltd, presently manufacturers and sells Tencel fibers. Lyocell fibers are particularly suitable for use in nonwoven applications because of their characteristic soft feel, water absorption, microdiameter size, and biodegradability and/or compostability. Most lyocell fibers are produced from high quality wood pulps that have been extensively processed to remove non-cellulose components, especially hemicelluloses. These highly processed pulps are referred to as dissolving grade or high a (high alpha) pulps, in which the term a refers to the percentage of cellulose remaining after extraction with 17.5% caustic. Alpha cellulose can be determined by TAPPI 203. Thus a high a pulp contains a high percentage of cellulose, and a correspondingly low percentage of other components such as hemicelluloses. Typically, the cellulose for these high a pulps comes from both hardwoods and softwoods; softwoods generally having longer fibers than hardwoods. A lower cost alternative to high a dissolving grade pulps is a low a pulp having a higher percentage of hemicelluloses. These low a pulps have a low copper number, a low lignin content and a low transition metal content and a broad molecular weight distribution. Pulps which meet these requirements for low a pulps have been made and are described in U.S. Pat. Nos. 6,979,113, 6,686,093 and 6,706,876, assigned to the assignee of the present application.

[0146] In embodiments, the lyocell fibers suitable for use in the present invention are made from a pulp with greater than about 3% by weight hemicelluloses. In embodiments, the lyocell fibers contain from about 4 to about 18% by weight hemicelluloses as defined by the sum of the xylan and mannan content of the fibers.

[0147] In embodiments, the lyocell fibrous elements may comprise filaments, for example they may be continuous in length and/or may comprise fibers, for example they may be discontinuous in length, for example staple fibers that are cut from lyocell filaments.

[0148] In embodiments, the lyocell fibrous elements, for example lyocell fibers in the low basis weight nonwoven web of the present invention may exhibit an average fiber diameter of from 1 to 30 and/or 2 to 20 and/or 3 to 15 and/or 6 to 9 m as measured according to the Average Fiber Diameter Test Method described herein.

[0149] In embodiments, rayon is made by reacting wood pulp fibers and/or wood pulp chips and/or cotton linters with sodium hydroxide to produce alkali cellulose. The alkali cellulose is then combined and churned with carbon disulfide to produce sodium cellulose xanthate. The sodium cellulose xanthate is then bathed in sodium hydroxide which produces a viscous solution. The viscous solution is then spun and/or extruded into an acid bath that coagulates and solidifies the viscous solution into fibrous elements, for example filaments.

[0150] Rayon and lyocell filaments may be cut to staple fiber lengths, for example from about 6 mm to about 150 mm and/or from about 10 mm to about 60 mm and/or from about 15 mm to about 45 mm.

Methods for Making Low Basis Weight Nonwoven Web

[0151] Non-limiting examples of methods for making the low basis weight nonwoven web 14 of the present invention are shown in FIGS. 1-5.

[0152] In embodiments, as shown in FIG. 1, the low basis weight nonwoven web 14 of the present invention may be made by a low basis weight nonwoven web making process 38 shown in FIG. 1 by spinning a plurality of fibrous elements, for example filaments 28, for example hydroxyl polymer filaments, such as polyvinyl alcohol filaments and/or such as cellulose filaments, such as rayon and/or lyocell filaments, from one or more and/or two or more filament sources 40, such as a die, for example a meltblow die, such as a multi-row capillary meltblow die, and/or a spunbond die, to form a low basis weight nonwoven web 14 comprising a plurality of inter-entangled filaments 28.

[0153] In another example, as shown in FIG. 2, the low basis weight nonwoven web 14 of the present invention may be made by a low basis weight nonwoven web making process 38 shown in FIG. 2 by spinning a plurality of fibrous elements, for example filaments 28, for example hydroxyl polymer filaments, such as polyvinyl alcohol filaments and/or such as cellulose filaments, such as rayon and/or lyocell filaments, from one or more and/or two or more filament sources 40, such as a die, for example a meltblow die, such as a multi-row capillary meltblow die, and/or a spunbond die, and cutting the filaments 28 into a plurality of fibers 26, which are collected on a collection device 42 to form a low basis weight nonwoven web 14 comprising a plurality of fibers 26.

[0154] In yet another example, as shown in FIG. 3, the low basis weight nonwoven web 14 of the present invention may be made by a low basis weight nonwoven web making process 38 shown in FIG. 3 by depositing a plurality of fibrous elements, for example fibers 26, for example hydroxyl polymer fibers, such as polyvinyl alcohol fibers and/or such as cellulose fibers, such as rayon and/or lyocell fibers, from one or more and/or two or more fiber sources 44, such as air laid former, to form a low basis weight nonwoven web 14 comprising a plurality of fibers 26.

[0155] In even yet another example (not shown), the low basis weight nonwoven web 14 of the present invention may be made by a low basis weight nonwoven web making process 38 similar to that shown in FIG. 3, but where both filaments and fibers are commingled together, for example in a coforming process, and collecting the commingled filaments and fibers, for example hydroxyl polymer filaments and fibers, such as polyvinyl alcohol filaments and/or fibers and/or such as cellulose filaments and/or fibers, such as rayon and/or lyocell filaments and/or fibers, on a collection device 42 to form a low basis weight nonwoven web comprising a plurality of filaments and fibers.

[0156] The low basis weight nonwoven web making process 38 may further comprise the step of associating the filaments 28 and/or fibers 26, for example by bonds, such as thermal bonds to provide the low basis weight nonwoven web 14 with strength and integrity. The step of associating may comprise the step of passing the low basis weight nonwoven web 14 through a nip (not shown) formed by at least one thermal bond roll, for example a patterned thermal bond roll and a flat roll.

[0157] Further, the low basis weight nonwoven web making process 38 may optionally comprise the step of winding the low basis weight nonwoven web 14 into a roll 34, such as a parent roll. The roll 34 of the low basis weight nonwoven web 14 may be unwound in a converting operation for further processing.

[0158] Non-limiting examples of filaments 28 according to the present invention are produced by spinning a filament-forming composition, for example a filament-forming composition that is suitable for making filaments 28.

[0159] The filaments 28 may be collected on a collection device 42, such as a belt or fabric, in embodiments a belt or fabric capable of imparting a pattern, for example a non-random repeating pattern to a low basis weight nonwoven web 14 formed as a result of collecting the filaments 28 on the collection device 42, such as a belt or fabric.

[0160] In embodiments of the present invention as shown in FIG. 1, a method 38 for making a low basis weight nonwoven web 14, for example a single-ply low basis weight nonwoven web, comprises the steps of: [0161] a. providing a polymer composition, for example a hydroxyl polymer composition comprising a hydroxyl polymer, for example a non-naturally occurring hydroxyl polymer, for example a water-soluble hydroxyl polymer, such as a polyvinyl alcohol; [0162] b. spinning the polymer composition, for example from a filament source 40, such as a die, for example a meltblow die and/or a spunbond die, to form a plurality of filaments 28; and [0163] c. collecting the plurality of filaments 28 on a collection device 42 to form a low basis weight nonwoven web 14 of the present invention as shown in FIG. 4, for example a single-ply low basis weight nonwoven web, for example such that the low basis weight nonwoven web 14 exhibits a basis weight of less than 5 gsm and/or less than 4 gsm and/or less than 3 gsm and/or less than 2 gsm to greater than 0.25 gsm and/or to greater than 0.5 gsm and/or to greater than 0.75 gsm and/or to at least 1 gsm as measured according to the Basis Weight Test Method described herein; and [0164] d. optionally, winding the low basis weight nonwoven web 14, for example a single-ply low basis weight nonwoven web, convolutely about itself to form a roll 34 of the low basis weight nonwoven web 14.

[0165] In another example of the present invention as shown in FIG. 1, a method 38 for making a low basis weight nonwoven web 14, for example a single-ply low basis weight nonwoven web, comprises the steps of: [0166] a. providing a polymer composition, for example a hydroxyl polymer composition comprising a hydroxyl polymer, for example a non-naturally occurring hydroxyl polymer, for example a non-water soluble hydroxyl polymer, such as cellulose, for example rayon and/or lyocell; [0167] b. spinning the polymer composition, for example from a filament source 40, such as a die, for example a meltblow die and/or a spunbond die, to form a plurality of filaments 28; and [0168] c. collecting the plurality of filaments 28 on a collection device 42 to form a low basis weight nonwoven web 14 of the present invention as shown in FIG. 4, for example a single-ply low basis weight nonwoven web, for example such that the low basis weight nonwoven web 14 exhibits a basis weight of less than 5 gsm and/or less than 4 gsm and/or less than 3 gsm and/or less than 2 gsm to greater than 0.25 gsm and/or to greater than 0.5 gsm and/or to greater than 0.75 gsm and/or to at least 1 gsm as measured according to the Basis Weight Test Method described herein; and [0169] d. optionally, winding the low basis weight nonwoven web 14, for example a single-ply low basis weight nonwoven web, convolutely about itself to form a roll 34 of the low basis weight nonwoven web 14.

[0170] In another example of the present invention as shown in FIG. 2, a method for making a low basis weight nonwoven web 14, for example a single-ply low basis weight nonwoven web, comprises the steps of: [0171] a. providing a polymer composition, for example a hydroxyl polymer composition comprising a hydroxyl polymer, for example a non-naturally occurring hydroxyl polymer, for example a water-soluble hydroxyl polymer, such as a polyvinyl alcohol; [0172] b. spinning the polymer composition to form a one or more filaments 28; [0173] c. cutting the one or more filaments 28 to form a plurality of fibers 26; and [0174] d. collecting the plurality of fibers 26 on a collection device 42 as shown in FIG. 2 to form a low basis weight nonwoven web 14 of the present invention as shown in FIG. 5, for example a single-ply low basis weight nonwoven web, for example such that the low basis weight nonwoven web 14 exhibits a basis weight of less than 5 gsm and/or less than 4 gsm and/or less than 3 gsm and/or less than 2 gsm to greater than 0.25 gsm and/or to greater than 0.5 gsm and/or to greater than 0.75 gsm and/or to at least 1 gsm as measured according to the Basis Weight Test Method described herein; and [0175] e. optionally, winding the low basis weight nonwoven web 14, for example a single-ply low basis weight nonwoven web, convolutely about itself to form a roll 34 of the low basis weight nonwoven web 14.

[0176] In yet another example of the present invention as shown in FIG. 2, a method for making a low basis weight nonwoven web 14, for example a single-ply low basis weight nonwoven web, comprises the steps of: [0177] a. providing a polymer composition, for example a hydroxyl polymer composition comprising a hydroxyl polymer, for example a non-naturally occurring hydroxyl polymer, for example a non-water soluble hydroxyl polymer, such as cellulose, for example rayon and/or lyocell; [0178] b. spinning the polymer composition to form one or more filaments 28; [0179] c. cutting the one or more filaments 28 to form a plurality of fibers 26; and [0180] d. collecting the plurality of fibers 26 on a collection device 42 as shown in FIG. 2 to form a low basis weight nonwoven web 14 of the present invention as shown in FIG. 5, for example a single-ply low basis weight nonwoven web, for example such that the low basis weight nonwoven web 14 exhibits a basis weight of less than 5 gsm and/or less than 4 gsm and/or less than 3 gsm and/or less than 2 gsm to greater than 0.25 gsm and/or to greater than 0.5 gsm and/or to greater than 0.75 gsm and/or to at least 1 gsm as measured according to the Basis Weight Test Method described herein; and [0181] e. optionally, winding the low basis weight nonwoven web 14, for example a single-ply low basis weight nonwoven web, convolutely about itself to form a roll 34 of the low basis weight nonwoven web 14.

[0182] In even another example of the present invention as shown in FIG. 3, a method for making a low basis weight nonwoven web 14, for example a single-ply low basis weight nonwoven web, comprises the steps of: [0183] a. providing a plurality of fibers 26, for example hydroxyl polymer fibers, for example non-naturally occurring hydroxyl polymer fibers, for example water-soluble hydroxyl polymer fibers, such as polyvinyl alcohol fibers; and [0184] b. depositing the plurality of fibers 26, for example from one or more fiber sources 44, such as an air laid former, onto a collection device 42 as shown in FIG. 3 to form a low basis weight nonwoven web 14 of the present invention as shown in FIG. 5, for example a single-ply low basis weight nonwoven web, for example such that the low basis weight nonwoven web 14 exhibits a basis weight of less than 5 gsm and/or less than 4 gsm and/or less than 3 gsm and/or less than 2 gsm to greater than 0.25 gsm and/or to greater than 0.5 gsm and/or to greater than 0.75 gsm and/or to at least 1 gsm as measured according to the Basis Weight Test Method described herein; and [0185] c. optionally, winding the low basis weight nonwoven web 14, for example a single-ply low basis weight nonwoven web, convolutely about itself to form a roll 34 of the low basis weight nonwoven web 14.

[0186] In even yet another example of the present invention as shown in FIG. 3, a method for making a low basis weight nonwoven web 14, for example a single-ply low basis weight nonwoven web, comprises the steps of: [0187] a. providing a plurality of fibers 26, for example hydroxyl polymer fibers, for example non-naturally occurring hydroxyl polymer fibers, for example non-water-soluble hydroxyl polymer fibers, for example cellulose fibers, such as rayon and/or lyocell fibers; and [0188] b. depositing the plurality of fibers 26, for example from one or more fiber sources 44, such as an air laid former, onto a collection device 42 as shown in FIG. 3 to form a low basis weight nonwoven web 14 of the present invention as shown in FIG. 5, for example a single-ply low basis weight nonwoven web, for example such that the low basis weight nonwoven web 14 exhibits a basis weight of less than 5 gsm and/or less than 4 gsm and/or less than 3 gsm and/or less than 2 gsm to greater than 0.25 gsm and/or to greater than 0.5 gsm and/or to greater than 0.75 gsm and/or to at least 1 gsm as measured according to the Basis Weight Test Method described herein; and [0189] c. optionally, winding the low basis weight nonwoven web 14, for example a single-ply low basis weight nonwoven web, convolutely about itself to form a roll 34 of the low basis weight nonwoven web 14.

[0190] In embodiments, the spinning steps of the methods of the present invention may comprise spinning the polymer composition with a die, such as a multi-row capillary meltblow die and/or a knife edge meltblow die. In embodiments the spinning steps comprise spinning the polymer composition with an example of a multi-row capillary meltblow die 46 as shown in FIG. 6, which comprises a plurality of filament-forming holes 48 associated with one or more fluid releasing holes 50 that permit an attenuation fluid to exit the multi-row capillary meltblow die 46 substantially parallel to a polymer composition exiting a corresponding filament-forming hole 48 such that the polymer composition forms a filament 28. In another example, the spinning steps may comprise spinning the polymer composition with a spunbond die. The fibrous elements spun from the dies may be continuous, for example filaments, and/or discontinuous, for example fibers.

[0191] In embodiments, the methods of the present invention may further comprise the step of convolutely winding the low basis weight nonwoven web into a roll to form a roll of the low basis weight nonwoven web, for example a parent roll of the low basis weight nonwoven web.

[0192] In still another example, the methods of the present invention may be close coupled and/or direct coupled, such that after forming the low basis weight nonwoven web, the web is transferred to a subsequent operation such as combining with another fibrous structure, for example a wet laid fibrous structure.

[0193] In embodiments, the low basis weight nonwoven web of the present invention is formed from a plurality of hydroxyl polymer fibrous elements, for example filaments, which can be made unexpectedly by forming the low basis weight nonwoven web at a speed of less than 500 feet/minute (fpm) and/or less than 400 fpm and/or less than 300 fpm and/or less than 200 fpm to greater than 25 fpm and/or to greater than 50 fpm and/or to greater than 100 fpm and/or to greater than 125 fpm. To aid in the release of the low basis weight nonwoven web from a collection device, for example a belt, if one is present, upon which the low basis weight nonwoven web may be formed, any vacuum that functions to assist in drawing the fibrous elements, for example filaments, of the low basis weight nonwoven web onto a surface of the collection device is operated at conditions, for example vacuum air at less than 400 SCFM that do not inhibit the release of the low basis weight nonwoven web from the collection device and that do not damage the low basis weight nonwoven web by creating holes and/or other defects in the low basis weight nonwoven web during formation and optionally winding of the low basis weight nonwoven web into the form of a convolutely wound roll.

Comparative Example

[0194] A typical nonwoven web of melt blown polyvinyl alcohol filaments has a basis weight of 30 gsm and is composed of individual filaments that have an average fiber diameter of roughly 20 microns. Normalized to basis weight, the resulting web has a MD fail total energy absorbed (TEA) of 5 g/in per gsm. The relatively low TEA per gsm is because there are few fibers and fiber-to-fiber contacts. A basis weight of 30 gsm is required to make a product with sufficient mechanical properties to compensate for the low density of fiber-to-fiber contacts between the 20 micron diameter filaments. Consequently, without sufficient basis weight, the MD fail TEA is not high enough to withstand the forces of the winding and unwinding steps during web processing and handling which results in web loss.

Non-Limiting Examples of Making a Low Basis Weight Nonwoven Web

Example 1APolyvinyl Alcohol Low Basis Weight Nonwoven Web

[0195] A 1.5 gsm polyvinyl alcohol low basis weight nonwoven web according to the present invention is formed as follows.

[0196] 6 kg of Poval10-98 polyvinyl alcohol (98% hydrolysis Kuraray), which has a weight average molecular weight of 50,000 g/mol, and 12 kg of water are added into a scraped, wall pressure vessel equipped with an overhead agitator in order to target a 33 wt % polyvinyl alcohol aqueous polymer composition. The 33 wt % polyvinyl alcohol aqueous polymer composition is then cooked under pressure at 240 F. for 4 hours until the resulting polyvinyl alcohol aqueous polymer composition is homogenous and transparent. The polyvinyl alcohol aqueous polymer composition is then pumped via a gear pump to a die, such as a meltblow die, for example a Biax-Fiberfilm Corporation multi-row capillary meltblow die.

[0197] Next, a method according to the present invention, for example as shown in FIG. 1, is used to form a plurality of polyvinyl alcohol filaments by spinning and optionally attenuating with a saturated air stream (about 150 F. and 1.8 psi), drying with high temperature air flow (about 450 F.) the polyvinyl alcohol filaments, and depositing the filaments onto a collection device, for example a belt, with vacuum air (about 350 SCFM) assisting with collecting the filaments onto the collection device. The collection device (belt) speed is about 175 feet per minute (fpm). The vacuum air is controlled to less than 400 SCFM by varying the fan speed in order to form the polyvinyl alcohol low basis weight nonwoven web of the present invention, for example as shown in FIG. 4, and to ensure satisfactory release of the polyvinyl alcohol low basis weight nonwoven web from the collection device and enable satisfactory winding into a roll, for example a parent roll, of the polyvinyl alcohol low basis weight nonwoven web. To facilitate satisfactory winding of and unwinding from the polyvinyl alcohol low basis weight nonwoven web parent roll, both the collection device (belt) and the polyvinyl alcohol low basis weight nonwoven web should be free from defects such as holes, spitters, or loose fiber edges. The resulting low basis weight polyvinyl alcohol web has a basis weight of 1.5 gsm and consists of filaments with an average fiber diameter of less than 4.5 microns. The small diameter filaments result in a relatively higher density of fiber-to-fiber contacts for a given basis weights compared to the Comparative Example which increases the MD total energy absorbed (TEA) properties of the web. Particularly, the normalized MD total energy absorbed (TEA) of the web is 13/g/in per gsm. Next, the polyvinyl alcohol low basis weight nonwoven web may then be wound into a roll, for example a parent roll, to form a polyvinyl alcohol low basis weight nonwoven web parent roll without web breaks and web losses due to the higher MD fail TEA per gsm.

Example 1BPolyvinyl Alcohol Low Basis Weight Nonwoven Web

[0198] A 1.5 gsm polyvinyl alcohol low basis weight nonwoven web according to the present invention is formed as follows.

[0199] 6 kg of Poval10-98 polyvinyl alcohol (98% hydrolysis Kuraray), which has a weight average molecular weight of 50,000 g/mol, and 12 kg of water are added into a scraped, wall pressure vessel equipped with an overhead agitator in order to target a 33 wt % polyvinyl alcohol aqueous polymer composition. The 33 wt % polyvinyl alcohol aqueous polymer composition is then cooked under pressure at 240 F. for 4 hours until the resulting polyvinyl alcohol aqueous polymer composition is homogenous and transparent. The polyvinyl alcohol aqueous polymer composition is then pumped via a gear pump to a die, such as a meltblow die, for example a Biax-Fiberfilm Corporation multi-row capillary meltblow die.

[0200] Next, a method according to the present invention, for example as shown in FIG. 2, is used to form a plurality of polyvinyl alcohol filaments by spinning and optionally attenuating with a saturated air stream (about 150 F. and 1.8 psi), and drying with high temperature air flow (about 450 F.) the polyvinyl alcohol filaments. The resulting low basis weight polyvinyl alcohol web has a basis weight between 1.5 gsm and 2 gsm and consists of filaments with an average fiber diameter of less than 4.5 microns. The MD total energy absorbed (TEA) of the web is 13/g/in/gsm. The filaments are then cut into a plurality of fibers and then the fibers are deposited onto a collection device, for example a belt, with vacuum air (about 350 SCFM) assisting with collecting the fibers onto the collection device. The collection device (belt) speed is about 175 feet per minute (fpm). The vacuum air is controlled to less than 400 SCFM by varying the fan speed in order to form the polyvinyl alcohol low basis weight nonwoven web of the present invention, for example as shown in FIG. 5, and to ensure satisfactory release of the polyvinyl alcohol low basis weight nonwoven web from the collection device and enable satisfactory winding into a roll, for example a parent roll, of the polyvinyl alcohol low basis weight nonwoven web. To facilitate satisfactory winding of and unwinding from the polyvinyl alcohol low basis weight nonwoven web parent roll, both the collection device (belt) and the polyvinyl alcohol low basis weight nonwoven web should be free from defects such as holes, spitters, or loose fiber edges. Next, the polyvinyl alcohol low basis weight nonwoven web may then be wound into a roll, for example a parent roll, to form a polyvinyl alcohol low basis weight nonwoven web parent roll without web breaks and web losses due to the higher MD fail TEA per gsm.

Example 1CPolyvinyl Alcohol Low Basis Weight Nonwoven Web

[0201] A 1.5 gsm polyvinyl alcohol low basis weight nonwoven web according to the present invention is formed as follows.

[0202] A plurality of polyvinyl alcohol fibers are deposited, for example by a process as shown in FIG. 3, onto a collection device, for example a belt, with vacuum air (about 350 SCFM) assisting with collecting the fibers onto the collection device. The collection device (belt) speed is about 175 feet per minute (fpm). The vacuum air is controlled to less than 400 SCFM by varying the fan speed in order to form the polyvinyl alcohol low basis weight nonwoven web of the present invention, for example as shown in FIG. 5, and to ensure satisfactory release of the polyvinyl alcohol low basis weight nonwoven web from the collection device and enable satisfactory winding into a roll, for example a parent roll, of the polyvinyl alcohol low basis weight nonwoven web. To facilitate satisfactory winding of and unwinding from the polyvinyl alcohol low basis weight nonwoven web parent roll, both the collection device (belt) and the polyvinyl alcohol low basis weight nonwoven web should be free from defects such as loose fiber edges. Next, the polyvinyl alcohol low basis weight nonwoven web may then be wound into a roll, for example a parent roll, to form a polyvinyl alcohol low basis weight nonwoven web parent roll.

Example 2ALyocell Low Basis Weight Nonwoven Web

[0203] A 2.0 gsm lyocell low basis weight nonwoven web according to the present invention is formed as follows.

[0204] Peach pulp, available from Weyerhaeuser Company, is dissolved in NMMO to prepare a solution of from about 8 to about 15% by weight level of cellulose in NMMO. Next, a method according to the present invention, for example as shown in FIG. 1, the solution is then spun via a die, for example a meltblow die, such as a Biax-Fiberfilm Corporation 12.7 cm multi-row capillary die (20 holes/cm), at a temperature of about 220 F. to produce a plurality of lyocell filaments (average fiber diameters of about 5 m as measured according to the Average Fiber Diameter Test Method described herein). While the lyocell filaments are attenuated with an air stream at 450 m/hour and 280 F., water is sprayed on the lyocell filaments between the die, for example the meltblow die, and a collection device, for example belt, (collection device (belt) speed of from about 5 to about 20 fpm) upon which the filaments are collected and form a precursor lyocell nonwoven web. The precursor lyocell low basis weight nonwoven web is then washed by spraying water using several beams of spray nozzles. After this last washing, the washed lyocell low basis weight nonwoven web is then passed through a squeeze roll to remove water to a solid content of about 9% resulting in a lyocell low basis weight nonwoven web according to the present invention, for example as shown in FIG. 4. Next, the lyocell low basis weight nonwoven web may then be wound into a roll, for example a parent roll, to form a lyocell low basis weight nonwoven web parent roll.

Example 2BLyocell Low Basis Weight Nonwoven Web

[0205] A 2.0 gsm lyocell low basis weight nonwoven web according to the present invention is formed as follows.

[0206] Peach pulp, available from Weyerhaeuser Company, is dissolved in NMMO to prepare a solution of from about 8 to about 15% by weight level of cellulose in NMMO. Next, a method according to the present invention, for example as shown in FIG. 2, is used to spin the solution via a die, for example a meltblow die, such as a Biax-Fiberfilm Corporation 12.7 cm multi-row capillary die (20 holes/cm), at a temperature of about 220 F. to produce a plurality of lyocell filaments (average fiber diameters of about 5 m as measured according to the Average Fiber Diameter Test Method described herein). While the lyocell filaments are attenuated with an air stream at 450 m/hour and 280 F., water is sprayed on the lyocell filaments between the die, for example the meltblow die, and a collection device, for example belt, (collection device (belt) speed of from about 5 to about 20 fpm). The filaments are then cut into a plurality of fibers. The fibers are then deposited onto the collection device to form a precursor lyocell low basis weight nonwoven web. The precursor lyocell low basis weight nonwoven web is then washed by spraying water using several beams of spray nozzles. After this last washing, the washed lyocell low basis weight nonwoven web is then passed through a squeeze roll to remove water to a solid content of about 9% resulting in a lyocell low basis weight nonwoven web according to the present invention, for example as shown in FIG. 5. Next, the lyocell low basis weight nonwoven web may then be wound into a roll, for example a parent roll, to form a lyocell low basis weight nonwoven web parent roll.

Example 2CLyocell Low Basis Weight Nonwoven Web

[0207] A 2.0 gsm lyocell low basis weight nonwoven web according to the present invention is formed as follows.

[0208] A plurality of lyocell fibers are deposited, for example by a process as shown in FIG. 3, onto a collection device, for example a belt, with vacuum air (about 350 SCFM) assisting with collecting the fibers onto the collection device. The collection device (belt) speed is about 175 feet per minute (fpm). The vacuum air is controlled to less than 400 SCFM by varying the fan speed in order to form the lyocell low basis weight nonwoven web of the present invention, for example as shown in FIG. 5, and to ensure satisfactory release of the lyocell low basis weight nonwoven web from the collection device and enable satisfactory winding into a roll, for example a parent roll, of the lyocell low basis weight nonwoven web. To facilitate satisfactory winding of and unwinding from the lyocell low basis weight nonwoven web parent roll, both the collection device (belt) and the lyocell low basis weight nonwoven web should be free from defects such as loose fiber edges. Next, the lyocell low basis weight nonwoven web may then be wound into a roll, for example a parent roll, to form a lyocell low basis weight nonwoven web parent roll.

Test Methods

[0209] Unless otherwise specified, all tests described herein including those described under the Definitions section and the following test methods are conducted on samples that have been conditioned in a conditioned room at a temperature of 23 C.1.0 C. and a relative humidity of 50%2% for a minimum of 24 hours prior to the test. All plastic and paper board packaging articles of manufacture, if any, must be carefully removed from the samples prior to testing. The samples tested are usable units. Usable units as used herein means sheets, flats from roll stock, pre-converted flats, fibrous structure, and/or single or multi-ply products. Except where noted all tests are conducted in such conditioned room, all tests are conducted under the same environmental conditions and in such conditioned room. Discard any damaged product. Do not test samples that have defects such as wrinkles, tears, holes, and like. All instruments are calibrated according to manufacturer's specifications.

Basis Weight Test Method

[0210] Basis weight of a fibrous structure is measured on stacks of twelve usable units using a top loading analytical balance with a resolution of 0.001 g. The balance is protected from air drafts and other disturbances using a draft shield. A precision cutting die, measuring 8.890 cm0.00889 cm by 8.890 cm0.00889 cm is used to prepare all samples.

[0211] With a precision cutting die, cut the samples into squares. Combine the cut squares to form a stack twelve samples thick. Measure the mass of the sample stack and record the result to the nearest 0.001 g.

[0212] The Basis Weight is calculated in g/m.sup.2 as follows:

[00001]$\mathrm{Basis}\mathrm{Weight}=\left(\mathrm{Mass}\mathrm{of}\mathrm{stack}\right)/\left[\left(\mathrm{Area}\mathrm{of}1\mathrm{square}\mathrm{in}\mathrm{stack}\right)\left(\mathrm{No}.\mathrm{of}\mathrm{squares}\mathrm{in}\mathrm{stack}\right)\right]\mathrm{Basis}\mathrm{Weight}\left(g/m^2\right)=\mathrm{Mass}\mathrm{of}\mathrm{stack}\left(g\right)/\left[79.032\left({\mathrm{cm}}^2\right)/10,000\left({\mathrm{cm}}^2/m^2\right)12\right]$

Report result to the nearest 0.1 g/m.sup.2. Sample dimensions can be changed or varied using a similar precision cutter as mentioned above, so as at least 645 square centimeters of sample area is in the stack.

Surface Average Fiber Diameter Test Method

[0213] The Surface Average Fiber Diameter Test Method measures the average fiber diameter of filaments of a surface material and/or present on a surface of a fibrous structure.

Apparatus:

[0214] SEM Quanta 450 FEG Scanning Electron Microscope or similar [0215] Commercial Software MIPAR Image Analysis Software version 3.3.4 [0216] Sample Preparation: [0217] Sample Preparation for Generating SEM Image: [0218] A 2 inch1.5 inch sample of a fibrous structure to be tested is cut, if necessary, from a fibrous structure. The sample is placed with the surface to be measured (the surface comprising the surface material, for example hydroxyl polymer filaments, to be measured) facing up on an SEM planchet with carbon double sided tape. The planchet is placed in a Denton sputter coater (or equivalent) for Au or Au/Pd coating, approximately 2 minutes using rotation to obtain an Au or Au/Pd coated sample.

[0219] Another sample preparation can be used to obtain the data, especially with fibrous structure that comprise a high basis weight of hydroxyl polymer filaments. This sample preparation utilizes tape stripping of the surface of the fibrous structure to be measured from a 2 inch1.5 inch sample of the fibrous structure. The tape stripped sample with the surface to be measured (the surface comprising the surface material, for example hydroxyl polymer filaments, to be measured) facing up on an SEM planchet with carbon double sided tape. The planchet is placed in a Denton sputter coater (or equivalent) for Au or Au/Pd coating, approximately 2 minutes using rotation to obtain an Au or Au/Pd coated sample. The use of this sample preparation for this Surface Average Fiber Diameter Test Method can be referred to as the Tape Stripping Surface Average Fiber Diameter Test Method.

Operation

Generation of SEM Image:

[0220] The coated sample is placed in the chamber of the SEM under high vacuum for imaging. Imaging is done at 3-5 kV accelerating voltage using the SE detector. Multiple images are obtained at 500 magnification and saved as .tif files for further analysis. If desired, the SEM measurement tool can be used to validate the scale bar at the bottom of the image. Image details in the data bar can include horizontal field width, magnification and scale bar along with additional parameters of the microscope.

[0221] A total number of ten sample images were collected and processed for each fibrous structure tested. In this case the average fiber diameter data generated represent an average of the ten images.

[0222] Method procedure for determining fiber diameter distribution using MIPAR from multiple SEM images (n=10) [0223] 1. Launch MIPAR [0224] Launch Batch Processor [0225] 2. Load Recipe [0226] Drag and drop provided recipe into the recipe panel [0227] Open recipe by selecting Load Recipe [0228] 3. Load Image [0229] Drag and drop images into the image panel [0230] Open image by selecting Add [0231] 4. Set Session [0232] Select Set Save Location to select a directory to save results to [0233] Edit the Session Name field with a meaningful name, such as sample name and date [0234] 5. Process [0235] Select Process [0236] Wait for processing to complete [0237] 6. View Results. [0238] Select View Results this will launch the Post Processor with your session automatically loaded [0239] 7. Generate Measurements [0240] Select Measure Features in the measurements panel [0241] Check Caliper Diameter [0242] Select View Measurement [0243] Only check Fiber Thickness [0244] 8. Export Measurement [0245] MIPAR will generate a table of all images, and all fiber diameters. [0246] Select Export to save date as CSV to open in Excel

[0247] Manual adjustments in sensitivity and corrections are performed after image processing, if necessary, for example if the image exhibits lower fiber contrast to the background and/or if there is background noise during segmentation.

[0248] The processed images are used to generate fiber diameter distribution of these samples by calculating the average fiber diameter of filaments of less than 4.0 m from the images.

[0249] In addition, from the data generated, the amount (frequency) of fibers having fiber diameters with buckets of fiber diameter ranges (0.5-1.0 m, 1.0-1.5 m, and 1.5-2.0 m) can be determined, which can also be shown in a histogram produced from the data.

[0250] For the present invention, in embodiments of the present invention, the fibrous structure may comprise a surface and/or surface material comprising filaments, for example hydroxyl polymer filaments, such as polyvinyl alcohol filaments, at a frequency of greater than 8000 and/or greater than 9000 and/or greater than 10000 and/or greater than 11000 and/or greater than 12000 and/or greater than 13000 and/or greater than 14000 and/or greater than 15000 in the 0.5-1.0 m bucket.

[0251] In another example of the present invention, the fibrous structure may comprise a surface and/or surface material comprising filaments, for example hydroxyl polymer filaments, such as polyvinyl alcohol filaments, at a frequency of greater than 5500 and/or greater than 6000 and/or greater than 7000 and/or greater than 8000 and/or greater than 9000 and/or greater than 10000 in the 1.0-1.5 m bucket.

[0252] In yet another example of the present invention, the fibrous structure may comprise a surface and/or surface material comprising filaments, for example hydroxyl polymer filaments, such as polyvinyl alcohol filaments, at a frequency of greater than 5000 and/or greater than 6000 and/or greater than 7000 and/or greater than 8000 in the 1.5-2.0 m bucket.

[0253] In even another example of the present invention, the fibrous structure may comprise a surface and/or surface material comprising filaments, for example hydroxyl polymer filaments, such as polyvinyl alcohol filaments, at a total frequency of greater than 18000 and/or greater than 20000 and/or greater than 25000 and/or greater than 30000 and/or greater than 32000 in the 0.5-1.0 m+1.0-1.5 m+1.5-2.0 m buckets, in other words, the sum of the frequencies from each of the 0.5-1.0 m, 1.0-1.5 m, and 1.5-2.0 m buckets.

Average Diameter Test Method

[0254] This Average Diameter Test Method is used to determine the average diameters of fibrous elements, such as filaments and/or fibers, where their known average diameters are not already known. For example, average diameters of commercially available fibers, such as rayon fibers, have known lengths whereas average diameters of spun filaments, such as spun hydroxyl polymer filaments, would be determined as set forth immediately below. Further, pulp fibers, such as wood pulp fibers, especially commercially available wood pulp fibers would have known diameter (width) from the supplier of the wood pulp or are generally known in the industry and/or can ultimately be measured according to the Kajaani FiberLab Fiber Analyzer SubTest Method described below.

[0255] A fibrous structure comprising filaments of appropriate basis weight (approximately 5 to 20 grams/square meter) is cut into a rectangular shape sample, approximately 20 mm by 35 mm. The sample is then coated using a SEM sputter coater (EMS Inc, PA, USA) with gold so as to make the filaments relatively opaque. Typical coating thickness is between 50 and 250 nm. The sample is then mounted between two standard microscope slides and compressed together using small binder clips. The sample is imaged using a 10 objective on an Olympus BHS microscope with the microscope light-collimating lens moved as far from the objective lens as possible. Images are captured using a Nikon D1 digital camera. A Glass microscope micrometer is used to calibrate the spatial distances of the images. The approximate resolution of the images is 1 m/pixel. Images will typically show a distinct bimodal distribution in the intensity histogram corresponding to the filaments and the background. Camera adjustments or different basis weights are used to achieve an acceptable bimodal distribution. Typically, 10 images per sample are taken and the image analysis results averaged.

[0256] The images are analyzed in a similar manner to that described by B. Pourdeyhimi, R. and R. Dent in Measuring fiber diameter distribution in nonwovens (Textile Res. J. 69 (4) 233-236, 1999). Digital images are analyzed by computer using the MATLAB (Version. 6.1) and the MATLAB Image Processing Tool Box (Version 3.) The image is first converted into a grayscale. The image is then binarized into black and white pixels using a threshold value that minimizes the intraclass variance of the thresholded black and white pixels. Once the image has been binarized, the image is skeletonized to locate the center of each fiber in the image. The distance transform of the binarized image is also computed. The scalar product of the skeletonized image and the distance map provides an image whose pixel intensity is either zero or the radius of the fiber at that location. Pixels within one radius of the junction between two overlapping fibers are not counted if the distance they represent is smaller than the radius of the junction. The remaining pixels are then used to compute a length-weighted histogram of filament diameters contained in the image.

Kajaani FiberLab Fiber Analyzer SubTest Method

Instrument Start-Up:

[0257] 1. Turn on Kajaani FiberLab Fiber Analyzer unit first, then computer and monitor. [0258] 2. Start FiberLab program on computer.

Instrument Operation:

[0259] 1. File.fwdarw.New (or click on New File icon) [0260] 2. New Fiber Analysis screen pops up. [0261] a. Sample Point: select the folder you would like data stored in (to add a new folder see Adding a New Folder [0262] b. Name: add condition or sample name/identifier here [0263] c. Date [0264] d. Time [0265] e. Sample Weight: mg of dry fiber in the 50 ml sample (can leave blank if NOT measuring for coarseness). This is the number calculated in #10 of Sample Prep below. [0266] 3. Make sure 50 ml of sample is placed in a Kajaani beaker and click Start [0267] 4. Optional: Distribution.fwdarw.Measured Values [0268] a. Fibers: the final count of measured fibers should be at least 10,000 [0269] b. Fibers/sec: this number must stay below 70 fibers/sec or the sample will automatically be diluted. If the sample is diluted during an analysis, the coarseness value will be invalid and will need to be discarded. [0270] 5. A bar indicating the measurement status of a sample appears on the computer monitor. Do not start an analysis until the indicated status is Wait State. When the analysis is completed, wait for Wait State to appear, then close the New Fiber Analysis window. You can now repeat #1- [0271] 6. When finished with all samples, close the FiberLab program before turning off the Kajaani FiberLab analyzer unit. [0272] 7. Shutdown computer.

Sample Preparation:

Target Sample Size:

[0273] Softwood: 4 mg/50 ml.fwdarw.160 mg BD in 2000 ml (170-175 mg from sheet) [0274] Hardwood: 1 mg/50 ml.fwdarw.40 mg BD in 2000 ml (40-45 mg from sheet) [0275] 1. For n=3 analysis, weigh and record weight of sample torn (avoiding cut edges) from 3 different pulp sheets of same sample using guidelines above for sample size. Place weighed samples into a suitable container for soaking of pulp. [0276] 2. Using the 3 sheets that samples were torn from, perform moisture content analysis. Note: This step can be skipped if coarseness measurement is not required. [0277] 3. Calculate the actual bone dry weight of the samples weighed in #1, by using the average moisture determined in #2. [0278] 4. Allow pulp samples to soak in water for 10-15 minutes. [0279] 5. Place 1.sup.st sample and soaking water into the Kajaani manual disintegrator. Fill disintegrator up to 250 ml mark with more water. [0280] 6. Using the hand dasher, plunge up and down until sample is separated into individual fibers. [0281] 7. Transfer sample to a 2000 ml volumetric flask. Make sure to wash off and collect any fibers that may have adhered to the dasher. [0282] 8. Dilute up to 2000 ml mark. It is important to be as precise as possible for repeatable coarseness results. [0283] 9. Take a 50 ml aliquot and place into a Kajaani beaker. Place beaker on the sampler unit. [0284] 10. Calculate the mg of BD pulp in 50 ml aliquot [0285] a. (BD mg of sample/2000 ml)50 ml [0286] 11. Begin Step #1 above in Instrument Operation

[0287] The water used in this method is City of Cincinnati Water or equivalent having the following properties: Total Hardness=155 mg/L as CaCO.sub.3; Calcium content=33.2 mg/L; Magnesium content=17.5 mg/L; Phosphate content=0.0462

Adding a New Folder to Sample Point Menu:

[0288] 1. Settings.fwdarw.Common Settings.fwdarw.Sample Folders [0289] a. Type in name of new folder.fwdarw.Add.fwdarw.OK [0290] Note: You must close the FiberLab program and re-open program to see the new folder appear in the menu.

Collecting Data in Excel File:

[0291] 1. Start FiberLab's Collect 1.12 program. [0292] 2. Open Windows Explorer (not to full screen-you must be able to see both the Explorer and the Collect windows. [0293] 3. In Windows Explorer . . . Select folder that data was stored in [0294] 4. Highlight data to be put in Excel.fwdarw.right click on Copy.fwdarw.drag highlighted samples to the Collect window.fwdarw.Save text [0295] 5. Click Save In menu bar and select My briefcase. Open the 2007 folder, type in file name and click Save. A message will appear saying the selected samples have been saved. Click OK (the sample names will disappear from the Collect window. [0296] 6. Open Excel. Then . . . Open.fwdarw.Look In My Briefcase.fwdarw.2007.fwdarw.at bottom, select All Files (*.*) in the Files of Type bar.fwdarw.find text file just saved and open.fwdarw.click thru the Text Import Wizard screens (next, next, finish)

Caliper Test Method

[0297] Caliper of a toilet tissue and/or fibrous structure ply is measured using a ProGage Thickness Tester (Thwing-Albert Instrument Company, West Berlin, NJ) with a pressure foot diameter of 5.08 cm (area of 6.45 cm.sup.2) at a pressure of 14.73 g/cm.sup.2. Four (4) samples are prepared by cutting of a usable unit such that each cut sample is at least 16.13 cm per side, avoiding creases, folds, and obvious defects. An individual specimen is placed on the anvil with the specimen centered underneath the pressure foot. The foot is lowered at 0.076 cm/sec to an applied pressure of 14.73 g/cm.sup.2. The reading is taken after 3 sec dwell time, and the foot is raised. The measure is repeated in like fashion for the remaining 3 specimens. The caliper is calculated as the average caliper of the four specimens and is reported in mils (0.001 in) to the nearest 0.1 mils.

Dry Tensile Test Method: Elongation, Tensile Strength, TEA and Modulus

[0298] Elongation, Tensile Strength, TEA and Tangent Modulus are measured on a constant rate of extension tensile tester with computer interface (a suitable instrument is the EJA Vantage from the Thwing-Albert Instrument Co. Wet Berlin, NJ) using a load cell for which the forces measured are within 10% to 90% of the limit of the load cell. Both the movable (upper) and stationary (lower) pneumatic jaws are fitted with smooth stainless steel faced grips, with a design suitable for testing 1 inch wide sheet material (Thwing-Albert item #733GC). An air pressure of about 60 psi is supplied to the jaws.

[0299] Twenty usable units of fibrous structures are divided into four stacks of five usable units each. The usable units in each stack are consistently oriented with respect to machine direction (MD) and cross direction (CD). Two of the stacks are designated for testing in the MD and two for CD. Using a one inch precision cutter (Thwing Albert) take a CD stack and cut two, 1.00 in 0.01 in wide by at least 3.0 in long strips from each CD stack (long dimension in CD). Each strip is five usable unit layers thick and will be treated as a unitary specimen for testing. In like fashion cut the remaining CD stack and the two MD stacks (long dimension in MD) to give a total of 8 specimens (five layers each), four CD and four MD.

[0300] Program the tensile tester to perform an extension test, collecting force and extension data at an acquisition rate of 20 Hz as the crosshead raises at a rate of 4.00 in/min (10.16 cm/min) until the specimen breaks. The break sensitivity is set to 50%, i.e., the test is terminated when the measured force drops to 50% of the maximum peak force, after which the crosshead is returned to its original position.

[0301] Set the gage length to 2.00 inches. Zero the crosshead and load cell. Insert the specimen into the upper and lower open grips such that at least 0.5 inches of specimen length is contained each grip. Align specimen vertically within the upper and lower jaws, then close the upper grip. Verify specimen is aligned, then close lower grip. The specimen should be under enough tension to eliminate any slack, but less than 0.05 N of force measured on the load cell. Start the tensile tester and data collection. Repeat testing in like fashion for all four CD and four MD specimens.

[0302] Program the software to calculate the following from the constructed force (g) verses extension (in) curve:

[0303] Tensile Strength is the maximum peak force (g) divided by the product of the specimen width (1 in) and the number of usable units in the specimen (5), and then reported as g/in to the nearest 1 g/in.

[0304] Adjusted Gage Length is calculated to as the extension measured at 11.12 g of force (in) added to the original gage length (in).

[0305] Elongation is calculated as the extension at maximum peak force (in) divided by the Adjusted Gage Length (in) multiplied by 100 and reported as % to the nearest 0.1%.

[0306] Tensile Energy Absorption (TEA) is calculated as the area under the force curve integrated from zero extension to the extension at the maximum peak force (g*in), divided by the product of the adjusted Gage Length (in), specimen width (in), and number of usable units in the specimen (5). This is reported as g*in/in.sup.2 to the nearest 1 g*in/in.sup.2.

[0307] Replot the force (g) verses extension (in) curve as a force (g) verses strain curve. Strain is herein defined as the extension (in) divided by the Adjusted Gage Length (in).

[0308] Program the software to calculate the following from the constructed force (g) verses strain curve:

[0309] Tangent Modulus is calculated as the least squares linear regression using the first data point from the force (g) verses strain curve recorded after 190.5 g (38.1 g5 layers) force and the 5 data points immediately preceding and the 5 data points immediately following it. This slope is then divided by the product of the specimen width (2.54 cm) and the number of usable units in the specimen (5), and then reported to the nearest 1 g/cm.

[0310] The Tensile Strength (g/in), Elongation (%), TEA (g*in/in.sup.2) and Tangent Modulus (g/cm) are calculated for the four CD specimens and the four MD specimens. Calculate an average for each parameter separately for the CD and MD specimens.

Calculations:

[00002]$\mathrm{Geometric}\mathrm{Mean}\mathrm{Tensile}=\mathrm{Square}\mathrm{Root}\mathrm{of}\left[\mathrm{MD}\mathrm{Tensile}\mathrm{Strength}\left(g/\mathrm{in}\right)\mathrm{CD}\mathrm{Tensile}\mathrm{Strength}\left(g/\mathrm{in}\right)\right]\mathrm{Geometric}\mathrm{Mean}\mathrm{Peak}\mathrm{Elongation}=\mathrm{Square}\mathrm{Root}\mathrm{of}\left[\mathrm{MD}\mathrm{Elongation}\left(\%\right)\mathrm{CD}\mathrm{Elongation}\left(\%\right)\right]\mathrm{Geometric}\mathrm{Mean}\mathrm{TEA}=\mathrm{Square}\mathrm{Root}\mathrm{of}\left[\mathrm{MD}\mathrm{TEA}\left(g*\mathrm{in}/{\mathrm{in}}^2\right)\mathrm{CD}\mathrm{TEA}\left(g*\mathrm{in}/{\mathrm{in}}^2\right)\right]\mathrm{Geometric}\mathrm{Mean}\mathrm{Modulus}=\mathrm{Square}\mathrm{Root}\mathrm{of}\left[\mathrm{MD}\mathrm{Modulus}\left(g/\mathrm{cm}\right)\mathrm{CD}\mathrm{Modulus}\left(g/\mathrm{cm}\right)\right]\mathrm{Total}\mathrm{Dry}\mathrm{Tensile}\mathrm{Strength}\left(\mathrm{TDT}\right)=\mathrm{MD}\mathrm{Tensile}\mathrm{Strength}\left(g/\mathrm{in}\right)+\mathrm{CD}\mathrm{Tensile}\mathrm{Strength}\left(g/\mathrm{in}\right)\mathrm{Total}\mathrm{TEA}=\mathrm{MD}\mathrm{TEA}\left(g*\mathrm{in}/{\mathrm{in}}^2\right)+\mathrm{CD}\mathrm{TEA}\left(g*\mathrm{in}/{\mathrm{in}}^2\right)\mathrm{Total}\mathrm{Modulus}=\mathrm{MD}\mathrm{Modulus}\left(g/\mathrm{cm}\right)+\mathrm{CD}\mathrm{Modulus}\left(g/\mathrm{cm}\right)\mathrm{Tensile}\mathrm{Ratio}=\mathrm{MD}\mathrm{Tensile}\mathrm{Strength}\left(g/\mathrm{in}\right)/\mathrm{CD}\mathrm{Tensile}\mathrm{Strength}\left(g/\mathrm{in}\right)$

Wet Tensile Test Method

[0311] Wet tensile for a toilet tissue and/or fibrous structure ply is measured according to ASTM D829-97 for Wet Tensile Breaking Strength of Paper and Paper Products, specifically by method 11.2 Test Method BFinch Procedure. Wet tensile is reported in units of g/in. Initial Total Wet Tensile is measured immediately after saturation.

Wet Decay Test Method

[0312] Wet decay (loss of wet tensile) for a toilet tissue and/or fibrous structure ply is measured according to the Wet Tensile Test Method and is the wet tensile of the toilet tissue and/or fibrous structure ply after it has been standing in the soaked condition in the Finch Cup for 30 minutes. Wet decay is reported in units of %. Wet decay is the % loss of Initial Total Wet Tensile after the 30 minute soaking.

Flexural Rigidity Test Method

[0313] The Flexural Rigidity Test Method determines the overhang length of the present invention based on the cantilever beam principal. The distance a strip of sample can be extended beyond a flat platform before it bends through a specific angle is measured. The inter-action between sheet weight and sheet stiffness measured as the sheet bends or drapes under its own weight through the given angle under specified test conditions is used to calculate the sample Bend Length, Flexural Rigidity, and Bending Modulus.

[0314] The method is performed by cutting rectangular strips of samples of the fibrous structure to be tested, in both the cross direction and the machine direction. The Basis Weight of the sample is determined and the Dry Caliper of the samples is measured (as detailed previously). The sample is placed on a test apparatus that is leveled so as to be perfectly horizontal (ex: with a bubble level) and the short edge of the sample is aligned with the test edge of the apparatus. The sample is gently moved over the edge of the apparatus until it falls under its own weight to a specified angle. At that point, the length of sample overhanging the edge of the instrument is measured.

[0315] The apparatus for determining the Flexural Rigidity of fibrous structures is comprised of a rectangular sample support with a micrometer and fixed angle monitor. The sample support is comprised of a horizontal plane upon which the sample rectangle can comfortably be supported without any interference at the start of the test. As it is slowly pushed over the edge of the apparatus, it will bend until it breaks the plane of the fixed angle monitor, at which point the micrometer measures the length of overhang.

[0316] Eight samples of 25.4 mm101.5 mm-152.0 mm are cut in the machine direction (MD); eight more samples of the same size are cut in the cross direction (CD). It is important that adjacent cuts are made exactly perpendicular to each other so that each angle is exactly 90 degrees. Samples are arranged such that the same surface is facing up. Four of the MD samples are overturned and four of the CD samples are overturned and marks are made at the extreme end of each, such that four MD samples will be tested with one side facing up and the other four MD samples will be tested with the other side facing up. The same is true for the CD samples with four being tested with one side up and four with the other side facing up.

[0317] A sample is then centered in a channel on the horizontal plane of the apparatus with one short edge exactly aligned with the edge of the apparatus. The channel is slightly oversized for the sample that was cut and aligns with the orientation of the rectangular support, such that the sample does not contact the sides of the channel. A lightweight slide bar is lowered over the sample resting in the groove such that the bar can make good contact with the sample and push it forward over the edge of the apparatus. The leading edge of the slide bar is also aligned with the edge of the apparatus and completely covers the sample. The micrometer is aligned with the slide bar and measures the distance the slide bar, thus the sample, advances.

[0318] From the back edge of the slide bar, the bar and sample are pushed forward at a rate of approximately 8-13 cm per second until the leading edge of the sample strip bends down and breaks the plane of the fixed angle measurement, set to 45. At this point, the measurement for overhang is made by reading the micrometer to the nearest 0.5 mm and is reported in units of cm.

[0319] The procedure is repeated for each of the 15 remaining samples of the fibrous structure.

Calculations:

[0320] Flexural Rigidity is calculated from the overhang length as follows:

[00003]$\mathrm{Bend}\mathrm{Length}=\mathrm{Overhang}\mathrm{length}/2$

[0321] Where overhang length is the average of the 16 results collected.

[0322] The calculation for Flexural Rigidity (G) is:

[00004]$G=0.1629*W*C^3\left(\mathrm{mg}.Math.\mathrm{cm}\right)$

[0323] Where W is the sample basis weight in pounds/3000 ft.sup.2 and C is the bend length in cm. The constant 0.1629 converts units to yield Flexural Rigidity (G) in units of milligram.Math.cm.

[00005]$\mathrm{Bending}\mathrm{Modulus}\left(Q\right)=\mathrm{Flexural}\mathrm{Rigidity}\left(G\right)/\mathrm{Moment}\mathrm{of}\mathrm{Inertia}\left(I\right)\mathrm{per}\mathrm{unit}\mathrm{area}.Q=G/IQ=\frac{732*G}{\mathrm{Caliper}{\left(\mathrm{mils}\right)}^3}$

Roll Compressibility Test Method

[0324] Roll Compressibility (Percent Compressibility) is determined using the Roll Diameter Tester 1000 as shown in FIG. 7. It is comprised of a support stand made of two aluminum plates, a base plate 1001 and a vertical plate 1002 mounted perpendicular to the base, a sample shaft 1003 to mount the test roll, and a bar 1004 used to suspend a precision diameter tape 1005 that wraps around the circumference of the test roll. Two different weights 1006 and 1007 are suspended from the diameter tape to apply a confining force during the uncompressed and compressed measurement. All testing is performed in a conditioned room maintained at about 23 C.2 C. and about 50%2% relative humidity.

[0325] The diameter of the test roll is measured directly using a Pi tape or equivalent precision diameter tape (e.g. an Executive Diameter tape available from Apex Tool Group, LLC, Apex, NC, Model No. W606PD) which converts the circumferential distance into a diameter measurement so the roll diameter is directly read from the scale. The diameter tape is graduated to 0.01 inch increments with accuracy certified to 0.001 inch and traceable to NIST. The tape is 0.25 in wide and is made of flexible metal that conforms to the curvature of the test roll but is not elongated under the 1100 g loading used for this test. If necessary the diameter tape is shortened from its original length to a length that allows both of the attached weights to hang freely during the test, yet is still long enough to wrap completely around the test roll being measured. The cut end of the tape is modified to allow for hanging of a weight (e.g. a loop). All weights used are calibrated, Class F hooked weights, traceable to NIST.

[0326] The aluminum support stand is approximately 600 mm tall and stable enough to support the test roll horizontally throughout the test. The sample shaft 1003 is a smooth aluminum cylinder that is mounted perpendicularly to the vertical plate 1002 approximately 485 mm from the base. The shaft has a diameter that is at least 90% of the inner diameter of the roll and longer than the width of the roll. A small steel bar 1004 approximately 6.3 mm diameter is mounted perpendicular to the vertical plate 1002 approximately 570 mm from the base and vertically aligned with the sample shaft. The diameter tape is suspended from a point along the length of the bar corresponding to the midpoint of a mounted test roll. The height of the tape is adjusted such that the zero mark is vertically aligned with the horizontal midline of the sample shaft when a test roll is not present.

[0327] Condition the samples at about 23 C.2 C. and about 50%2% relative humidity for 2 hours prior to testing. Rolls with cores that are crushed, bent or damaged should not be tested. Place the test roll on the sample shaft 1003 such that the direction the paper was rolled onto its core is the same direction the diameter tape will be wrapped around the test roll. Align the midpoint of the roll's width with the suspended diameter tape. Loosely loop the diameter tape 1004 around the circumference of the roll, placing the tape edges directly adjacent to each other with the surface of the tape lying flat against the test sample. Carefully, without applying any additional force, hang the 100 g weight 1006 from the free end of the tape, letting the weighted end hang freely without swinging. Wait 3 seconds. At the intersection of the diameter tape 1008, read the diameter aligned with the zero mark of the diameter tape and record as the Original Roll Diameter to the nearest 0.01 inches. With the diameter tape still in place, and without any undue delay, carefully hang the 1000 g weight 1007 from the bottom of the 100 g weight, for a total weight of 1100 g. Wait 3 seconds. Again read the roll diameter from the tape and record as the Compressed Roll Diameter to the nearest 0.01 inch. Calculate percent compressibility to the according to the following equation and record to the nearest 0.1%:

[00006]$\%\mathrm{Compressibility}=\frac{\left(\mathrm{Orginal}\mathrm{Roll}\mathrm{Diameter}\right)-\left(\mathrm{Compressed}\mathrm{Roll}\mathrm{Diameter}\right)}{\mathrm{Original}\mathrm{Roll}\mathrm{Diameter}}100$

[0328] Repeat the testing on 10 replicate rolls and record the separate results to the nearest 0.1%. Average the 10 results and report as the Percent Compressibility to the nearest 0.1%.

Glide on Skin Test Method

[0329] The Glide Test Method measures the Force to Drag and Force Variability of a custom probe having a textured surface, designed to mimic skin, as it dragged across the surface of a fibrous structure sample by a Friction/Peel tester.

[0330] Testing is performed on a Friction/Peel tester fitted with a custom probe. A suitable Friction/Peel tester is a Thwing-Albert Model 2260 Friction/Peel Tester (Thwing-Albert Instrument Company, 14 W. Collings Ave. West Berlin, NJ 08091), or equivalent. A 2000 gram capacity load cell 102 is used, accurate to 0.25% of the measuring value, along with a cross-head arm 104 accurate to 0.01% per inch of travel distance.

[0331] The instrument must be located in and all testing performed in a conditioned room maintained at 23 C.2 C. and 50%2% relative humidity.

[0332] The sample platform is horizontally level, 20 inches (50.8 cm) long, by 6 inches (15.24 cm) wide and has a sample clamp on one end to secure the fibrous structure sample to be tested. The probe is manufactured from a cylindrical aluminum rod 13.20.2 mm in length, 15.00.2 mm in diameter. A round side of the aluminum rod is milled flat to facilitate attachment to an aluminum arm. The rounded testing surface of the probe has a custom textured surface applied to it, which is designed to mimic skin. The appropriate surface texture is a coating by the name Plasma 11000 Series PC-11015 (coating thickness 0.003/0.005 inches), which is applied by American Roller Company Plasma Coatings from Arlington, TN. The probe is attached near the end of the aluminum arm, approximately 13 cm in length, with the probe's long axis attached perpendicular to the long axis of the arm. A probe pin is attached to the end of the arm opposite the probe.

[0333] The instrument is turned on at least 30 minutes prior to initiating testing, and is calibrated and operated according to the manufacturer's instructions. The instrument is interfaced with a computer running the appropriate software to operate the instrument. Program the instrument to move the cross-head arm at a constant speed of 1.0 mm/sec for 40 cm, while collecting force and position data at an acquisition rate of 250 Hz.

[0334] The probe with the skin mimic surface is attached to the load cell and cross-head arm assembly by inserting the probe pin into an attachment hole in the load cell. A small level is placed on the probe arm, and the load cell and cross-head arm assembly is raised or lowered so that the probe arm is level and parallel to the sample platform. The load cell and cross-head arm assembly is positioned so that the trailing edge of the probe is located approximately 5 mm away from the sample clamp and zeroed at this position. A weighted vial, which will be placed on the probe during testing, is prepared by adding lead shot to the small plastic vial such that the total weight of the probe, arm, and weighted vial is 1000.1 grams.

[0335] A fibrous structure sample is prepared by cutting a 15 cm by 10 cm rectangular sample from a finished product. Test samples are selected to avoid perforations, creases or folds within the testing region. Prepare ten (10) substantially similar replicate samples for testing. All fibrous structure samples being tested are equilibrated in a controlled environment (23 C.2 C. and 50%2% RH) for at least 2 hours before testing.

[0336] The fibrous structure sample is laid directly on the sample platform so that a short end of the fibrous structure test sample is under the sample clamp and the fibrous structure sample 110 lies flat on the sample platform. The fibrous structure sample is positioned so that the region to be tested does not include a perforation. All testing is to be performed in the machine direction of the fibrous structure sample. The clamp is lowered to prevent the fibrous structure sample from moving during testing.

[0337] To prepare the probe for testing, an alcohol wipe is used to wipe down the surface of the skin mimic to remove any dust/oils/or debris. Set the probe aside in a manner that ensures the skin mimic surface does not touch anything prior to testing. If the skin mimic surface is worn or damaged replace it prior to testing. The skin mimic surface is allowed to fully dry before being used for testing. The probe is carefully placed on the fibrous structure sample, and the probe pin is inserted through the attachment hole in the load cell, such that the probe and arm are properly aligned to be parallel with the testing path. The weighted vial containing lead shot is carefully placed on the arm, positioned such that it is centered directly over the probe. The load cell is zeroed.

[0338] The testing procedure is initiated so that the probe is dragged by the cross-head arm at a speed of 1.0 mm/sec over the surface of the fibrous structure sample in the machine direction for a distance of 40 mm, while force and displaced distance readings are collected at a rate of 250 data points/sec.

[0339] This measurement procedure is repeated on the ten substantially similar replicate fibrous structure samples, such that ten individual force versus distance profiles are generated.

[0340] A test is considered invalid, and the data discarded if one or more of the following occurs during testing: The probe detaches from the load cell. The weighted vial falls off of the probe. The probe passes over a perforation in the fibrous structure sample. The fibrous structure sample rips, buckles, delaminates, or detaches from the clamp.

[0341] The Force to Drag value is calculated as the mean of the individual force data points collected between a distance of 5 mm and 35 mm, excluding data from the first 5 mm and the last 5 mm of the total 40 mm distance. The Force to Drag value is the average of the ten individual replicate values and is reported to the nearest 0.1 grams force.

[0342] The Force Variability value is calculated as the mean of the absolute value difference of each individual force data point from its local mean (mean absolute deviation from the local mean) between a distance of 5 mm and 35 mm, again excluding the first 5 mm and the last 5 mm of the total 40 mm distance. The local mean is calculated using a moving average of the force data within 2.5% of the total data field from each individual data point. For example, using the data rate of 250 points/sec and cross-head arm speed of 1 mm/sec over a 30 mm distance (40 mm25 mm), 7500 data points are collected during a test, so 2.5% of 7500 yields 188 pts. The moving average of the force data within a range of 188 data points of each individual data point is then used as the local mean for that point. The average of the absolute value difference of each individual data point from its local mean yields the Force Variability value for that test. The Force Variability value is the average of the ten individual replicate values and is reported to the nearest 0.1 grams force.

Weight Average Molecular Weight Test Method

[0343] The weight average molecular weight and the molecular weight distribution (MWD) are determined by Gel Permeation Chromatography (GPC) using a mixed bed column. The column (Waters linear ultrahydrogel, length/ID: 3007.8 mm) is calibrated with a narrow molecular weight distribution polysaccharide, 107,000 g/mol from Polymer Laboratories). The calibration standards are prepared by dissolving 0.024 g of polysaccharide and 6.55 g of the mobile phase in a scintillation vial at a concentration of 4 mg/ml. The solution sits undisturbed overnight. Then it is gently swirled and filtered with a 5 micron nylon syringe filter into an auto-sampler vial.

[0344] The filtered sample solution is taken up by the auto-sampler to flush out previous test materials in a 100 L injection loop and inject the present test material into the column. The column is held at 50 C. using a Waters TCM column heater. The sample eluded from the column is measured against the mobile phase background by a differential refractive index detector (Wyatt Optilab REX interferometric refractometer) and a multi-angle later light scattering detector (Wyatt DAWN Heleos 18 angle laser light detector) held at 50 C. The mobile phase is water with 0.03M potassium phosphate, 0.2M sodium nitrate, and 0.02% sodium azide. The flowrate is set at 0.8 mL/min with a run time of 35 minutes.

[0345] The dimensions and values disclosed herein are not to be understood as being strictly limited to the exact numerical values recited. Instead, unless otherwise specified, each such dimension is intended to mean both the recited value and a functionally equivalent range surrounding that value. For example, a dimension disclosed as 40 mm is intended to mean about 40 mm.

[0346] Every document cited herein, including any cross referenced or related patent or application and any patent application or patent to which this application claims priority or benefit thereof, is hereby incorporated herein by reference in its entirety unless expressly excluded or otherwise limited. The citation of any document is not an admission that it is prior art with respect to any invention disclosed or claimed herein or that it alone, or in any combination with any other reference or references, teaches, suggests or discloses any such invention. Further, to the extent that any meaning or definition of a term in this document conflicts with any meaning or definition of the same term in a document incorporated by reference, the meaning or definition assigned to that term in this document shall govern.

[0347] While particular embodiments of the present invention have been illustrated and described, it would be obvious to those skilled in the art that various other changes and modifications can be made without departing from the spirit and scope of the invention. It is therefore intended to cover in the appended claims all such changes and modifications that are within the scope of this invention.