NONWOVEN MATERIAL, USE OF THE NONWOVEN MATERIAL, AND WIPING CLOTH, DRYING CLOTH AND FACE MASK CONTAINING THE NONWOVEN MATERIAL

Abstract

The invention relates to a nonwoven as well as to a wipe, a face mask and a dryer sheet including the nonwoven, which includes a network of molded bodies, the nonwoven, in the dry state, having a specific opacity of greater than or equal to 1.0%.Math.m.sup.2/g. In order to create a nonwoven of low basis weight, which is easy to produce and has, without special modifications, a high specific opacity, it is proposed that the molded bodies are regenerated cellulosic molded bodies and are materially interconnected via node points to form the network, and the regenerated cellulosic molded bodies comprising monofilament sections extending between node points, whose diameter varies along their lengthwise extension and which have a diameter of less than or equal to 15 μm for at least 90% of their lengthwise extension.

Claims

1. A nonwoven, comprising a network of molded bodies, the nonwoven in the dry state, having a specific opacity of greater than or equal to 1.0%.Math.m.sup.2/g, wherein the molded bodies are regenerated cellulosic molded bodies and are materially interconnected via node points to form the network, wherein the regenerated cellulosic molded bodies comprise monofilament sections extending between node points, whose diameter varies along their lengthwise extension and which have a diameter of less than or equal to 15 μm for at least 90% of their lengthwise extension.

2. The nonwoven of claim 1, wherein the multifilament sections extending between node points comprise several materially interconnected and essentially parallel monofilament sections, wherein the multifilament sections have a diameter of less than or equal to 100 μm for at least 90% of their lengthwise extension.

3. The nonwoven of claim 1, wherein the regenerated cellulosic molded bodies form an essentially endless network without visible filament ends.

4. The nonwoven of claim 1, wherein the nonwoven is essentially free of matting agents and colorants.

5. The nonwoven of claim 1, wherein the nonwoven consists essentially of cellulose.

6. The nonwoven of claim 1, wherein the regenerated cellulosic molded bodies are solution-spun cellulosic molded bodies.

7. The nonwoven of claim 6, wherein the monofilament sections have a solid cross-section.

8. The nonwoven of claim 1, wherein the nonwoven is essentially free of binders or adhesives.

9. The nonwoven of claim 1, wherein the nonwoven is essentially free of copper and/or nickel.

10. The nonwoven of claim 9, wherein the nonwoven has a copper content of less than 5 ppm and/or a nickel content of less than 2 ppm.

11. The nonwoven of claim 1, wherein the monofilament sections have a diameter of less than or equal to 10 μm for at least 90% of their lengthwise extension.

12. The nonwoven of claim 1, wherein the monofilament sections have an average diameter of greater than or equal to 1 μm and less than or equal to 8 μm.

13. The nonwoven of claim 1, wherein the nonwoven, in the dry state, has a specific opacity of greater than or equal to 1.2%.Math.m.sup.2/g.

14. The nonwoven of claim 1, wherein the nonwoven has a basis weight of less than or equal to 70 g/m.sup.2.

15. The nonwoven of claim 1, wherein the nonwoven comprises at least one of a property-refining substance, a surface-refining substance, a property-changing substance, a surface-changing substance and processing-facilitating agents at a content of no more than 1% by weight.

16. The nonwoven of claim 1, wherein the network of regenerated cellulosic molded bodies comprises several interconnected layers.

17. A nonwoven of claim 1 for of use in hygiene products filters, industrial products, clothing, furnishings, automotive, or leisure products.

18. A wipe comprising the nonwoven of claim 1.

19. The wipe claim 18, wherein the nonwoven is impregnated with a lotion.

20. The wipe of claim 19, wherein the lotion is essentially non-water-based.

21. The nonwoven of claim 6, wherein the solution-spun cellulosic molded bodies are produced according to a lyocell process.

22. The nonwoven of claim 7, wherein the monofilament sections have a round cross-section.

23. The nonwoven of claim 11, wherein the monofilament sections have a diameter of less than or equal to 7 μm for at least 90% of their lengthwise extension.

24. The nonwoven of claim 13, wherein the nonwoven in the dry state has a specific opacity of greater or equal to 1.5%.Math.m.sup.2/g.

25. The nonwoven of claim 14, wherein the nonwoven has a basis weight of less than or equal to 35 g/m.sup.2.

26. The nonwoven of claim 25, wherein the nonwoven has a basis weight less than or equal to 20 g/m.sup.2.

27. The nonwoven of claim 15, wherein the nonwoven comprises at least one of a property-refining substance, a surface-refining substance, a property-changing substance, a surface-changing substance and processing-facilitating agents at a content of no more than 0.5% by weight.

28. A face mask comprising the nonwoven claim 1.

29. The face mask of claim 28, wherein the nonwoven is impregnated with a lotion.

30. The face mask of claim 29, wherein the lotion is essentially non-water-based.

31. A dryer sheet comprising the nonwoven claim 1.

32. The dryer sheet of claim 31, wherein the nonwoven is impregnated with a lotion.

33. The dryer sheet of claim 32, wherein the lotion is essentially non-water-based.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0065] Hereinafter, the embodiments of the invention are described with reference to the drawings, wherein:

[0066] FIG. 1 is a schematic view of a first embodiment of the nonwoven according to the invention;

[0067] FIG. 2 is a microscopic image of another embodiment of the nonwoven according to the invention;

[0068] FIG. 3 is a scatter chart for the illustration of the specific opacity of the nonwovens according to the invention of Examples B1 to B7;

[0069] FIG. 4 is a schematic view of the measuring method used to determine the specific opacity;

[0070] FIG. 5 a partially broken schematic plan view of a sample carrier for the determination of the diameters of the monofilament sections;

[0071] FIG. 6 a torn-off sectional view of a wipe;

[0072] FIG. 7 a torn-off sectional view of a dryer sheet; and

[0073] FIG. 8 a partially broken plan view of a face mask.

MODES OF CARRYING OUT THE INVENTION

[0074] FIG. 1 is a schematic view of a nonwoven 100 according to a first embodiment, which includes a network 1 of regenerated cellulosic molded bodies 2. At node points 3, the molded bodies 2 are materially interconnected to form the network 1. In the network 1, the molded bodies 2 include monofilament sections 4 each of which extends between node points 3. Apart from the monofilament sections 4, the molded bodies 2 also include multifilament sections 5 which, like the monofilament sections 4, also extend between node points 3 or are interconnected via the node points 3 to form the network 1 of molded bodies 2. Here, the monofilament sections 4 can, at the node points 3, be alternatively connected to other monofilament sections 4 or to multifilament sections 5.

[0075] In the dry state, the nonwoven 100 has a specific opacity of greater than or equal to 1.0%.Math.m.sup.2/g. In other embodiments, this specific opacity can be increased to up to 1.2%.Math.m.sup.2/g, and more preferably to up to 1.5%.Math.m.sup.2/g, depending on process parameters and basis weight range. FIG. 3, for example, shows a scatter chart 50 where the x-axis 51 represents the basis weight in g/m.sup.2, and the y-axis 52 represents the specific opacity in [%.Math.m.sup.2/g]. Here, each of the straight lines 53, 54, and 55 represents the lower limit for a specific opacity of 1.0%.Math.m.sup.2/g, 1.2%.Math.m.sup.2/g, and 1.5%.Math.m.sup.2/g, respectively. Here, each of the straight vertical lines 56, 57, and 58 stands for the limit values of the basis weight of 70 g/m.sup.2, 35 g/m.sup.2, and 20 g/m.sup.2, respectively. Here, each of the measuring points 60 stands for an embodiment B1 to B7 of the present invention. Here, each of the measuring points 61, 62, 63, and 64 stands for the comparison measurements V1 to V4. In the description of the examples, the details of the measuring points 60 to 64 are explained more fully.

[0076] The monofilament sections 4 according to the embodiment in FIG. 1 have a variable, varying diameter 7 along their lengthwise extension 6. In this connection, the diameters 7 of the monofilament sections 4, at least along 90% of the lengthwise extension 6 of the monofilament sections 4, are no more than 15 μm. In this connection, the monofilament sections 4, along their lengthwise extension 6, have an average diameter 7 between 1 μm and 8 μm.

[0077] In another embodiment, the diameter 7 of the monofilament sections 4 can, for at least 90% of their lengthwise extension 6, be no more than 10 μm, and, in a particularly advantageous embodiment, be no more than 7 μm. Due to stretching of the extruded spinning solution in the blown air stream at a high velocity and a turbulent current, the molded bodies obtain a diameter 7 that varies along their lengthwise extension 6. Therefore, the multifilament sections 5 formed due to the connection of several filaments in the blown air stream also have a diameter 9 that varies along their lengthwise extension 8. In this connection, the multifilament sections 5 have a diameter of less than or equal to 100 μm for at least 90% of their lengthwise extension 8.

[0078] The multifilament sections 5 are formed as a result of the material connection of individual filaments in the blown air stream and thus are essentially composed of several monofilament sections 4 which intrinsically are inseparably connected with one another, via cohesion of the cellulose molecules. Therefore, the multifilament sections 5 are not to be regarded as a strand of parallel monofilament sections 4, but rather as one single multifilament section 5 caused to be created by the connection of several filaments.

[0079] FIG. 2 is an electron microscope image at 250× magnification of a nonwoven 101 according to the invention. The nonwoven 101 includes, as previously described for FIG. 1, the network 1 of cellulosic molded bodies 2 that are connected via node points 3 and consist of monofilament sections 4 and multifilament sections 5.

[0080] The regenerated cellulosic molded bodies 2 in the nonwovens 100 and 101 according to FIGS. 1 and 2 form an endless network 1, wherein essentially no filament ends of the molded bodies 2 are visible. Due to the stretching process of the extruded spinning solution in the blown air stream, the individual filaments are materially connected to one another so that any ends of the filaments are connected to other filaments and form a node point 3. Thus, no loose filament ends can be identified, for example, in the microscopic image of the exemplary nonwoven 101 according to FIG. 2. However, it cannot be ruled out that, in further posttreatment steps of the nonwoven 100, 101—such as an additional hydroentangling process—filament ends are disengaged from the network 1 and thus will be present in a loose form in the nonwoven.

[0081] The molded bodies 2 of the nonwoven 101 are solution-spun cellulosic molded bodies 2 and were produced from a spinning solution containing cellulose, water, and NMMO according to the lyocell process. Once the cellulose has been precipitated and the nonwoven 101 has been washed, a nonwoven 101 according to the invention is obtained that, except for unavoidable impurities, consists only of cellulose. Furthermore, the nonwoven 101 includes no matting agents and colorants, which lends to it excellent strength and stability. In addition, the nonwoven 101 is free of adhesives or binders so that the mechanical flexibility of the nonwoven 101 is not adversely affected. Besides, the nonwoven 101 is well tolerated by skin, as it is free of metallic residues, especially copper and nickel.

[0082] In another embodiment, the nonwoven 100, 101 can include several interconnected layers, which, however, is not shown in detail in the figures. The connection of the layers can be materially via cohesion between the cellulose molecules of the molded bodies 2 or, for example, in a form-locking and/or force-locking manner by mechanical entanglement of the molded bodies 2—for example, as a result of a hydroentanglement process.

[0083] The nonwoven 100 according to the invention is particularly suitable for the production of a wipe 200, a face mask 300, and a dryer sheet 400, the nonwoven 100 having, in this case, a specific opacity of greater than or equal to 1.0% g m-2.

[0084] FIG. 6, for example, shows a wipe 200 that includes an afore-described nonwoven 100 according to the invention. In this case, the nonwoven 100 is impregnated with a lotion 210 which penetrates at least partially into the nonwoven 100 and forms a penetration area 215. In this case, the lotion 210 can contain a solvent such as water, however, it is preferably oil-based, fat-based, or wax-based and thus essentially free of water. Such a wipe 200 can—depending on the lotion 210—be equally suited for hygiene use and the treatment of surfaces.

[0085] FIG. 7 shows a dryer sheet 400 which also includes a nonwoven 100 according to the invention. Again, a lotion 410 has been applied to the nonwoven 100. In this case, the lotion 410 can be absorbed by the structure of the nonwoven 100 and wet it, which, however, is not shown in detail in the figures. In particular, the nonwoven 100 can be fully or partially wetted by the lotion 410. Preferably, the lotion 400 is free of aqueous solutions and will, at elevated temperatures, for example, during a drying process in a laundry dryer, be released to the laundry contained therein.

[0086] Lastly, FIG. 8 shows a face mask 300 which includes a nonwoven 100 as a base substrate and is, on its inner side (facing the face of the user), coated with a lotion 310. In this case, the lotion 310 is preferably configured such that it can be disengaged from the nonwoven 100 by the skin temperature of the user and be released toward the skin. In addition, the face mask 300 includes several cutouts 320 so as to conform readily to the face of the user.

[0087] FIGS. 3, 4, and 5 are described hereinafter in order to explain the examples.

EXAMPLES

Measurement of Specific Opacity:

[0088] From the nonwoven to be analyzed, a 10×10 cm random sample is taken, and, prior to performing the measurement, conditioned for 24 hours at 23° C. (±2° C.) and 50% (±5%) relative air humidity. Following such conditioning, the sample is weighed, and the basis weight in g/m.sup.2 is determined.

[0089] As the measuring instrument for all measurements, a Konica Minolta Inc. CM-600d spectrophotometer was equipped with a measuring head attachment for opacity measurements (Konica Minolta, not glazed, plastic, CM-A180 target mask 8 mm (w/o plate)), and the instrument was calibrated with the black standard (Konica Minolta Inc., CM-A182 Zero Calibration Box) as well as with the white standard (Konica Minolta Inc., CM-A177).

[0090] The measuring instrument settings and software used for all calibration measurements and opacity measurements are set forth in Table 1.

TABLE-US-00001 TABLE 1 Measuring instrument setup for calibration and measurements Software Konica Minolta Inc., Color Data Software CM- S100 w, SpectraMagicTM NX; Version: CM-S100w 2.70.0006 Gloss component SCE Output Reflection 570 nm Measurement area D = 8 mm Illumination area D = 11 mm First light type C Second light type (none) Observer 10°

[0091] For the determination of the opacity, an opacity test chart with a black region and a white region is used (TQC Test Chart, Format A4, art. no. VF2345).

[0092] The reflection values of a sample are measured above both black and white regions of the opacity test chart. FIG. 4 shows a schematic view of a sample 70 removed from a nonwoven 100 according to the invention by cutting or stamping. The sample 70 has edge lengths 71, 72 of 10 cm. The positions 73, 74, 75, 76, and 77 where the measuring points 1 to 5 are recorded are in each of the corners and in the center of the sample 70.

[0093] At first, the sample 70 is positioned above the black region 81 of the opacity test chart 80, and the measuring points 1 to 5 for the reflection of the sample above black are determined. Subsequently, the sample 70 is positioned above the white region 82 of the opacity test chart 80, and recording the measuring points 1 to 5 is repeated for the reflection of the sample above white.

[0094] Then, the opacity of the sample for the measuring points 1, 2, 3, 4, and 5 can be calculated separately according to formula (2):

opacity [%]=100.Math.reflection above black/reflection above white,   (2)

[0095] wherein reflection above black stands for the reflection of the sample above the black opacity test chart background at a wavelength of 570 nm and, in turn, reflection above white refers to the reflection of the sample above the white opacity test chart background at a wavelength of 570 nm.

[0096] Subsequently, the average value of the opacity values is calculated across all 5 measuring points and the specific opacity of the sample is determined according to Formula (1), as previously defined, as a division of the average value by the basis weight of the sample:

specific opacity [%.Math.m.sup.2/g]=opacity [%]/basis weight [g/m.sup.2].   (1)

[0097] Here, the specific opacity stands for the opacity normalized per basis weight of the sample.

Microscopic Determination of the Diameters of the Monofilament Sections:

[0098] For determining the diameters of the monofilament sections, a 1 cm×1 cm random sample 90 was removed from the nonwoven and, before conducting the measurement, conditioned for 24 hours at 23° C. (±2° C.) and 50% (±5%) relative air humidity.

[0099] Subsequently, the sample 90 was, as shown in FIG. 5, placed on a transparent sample carrier 91 and covered with a cover glass 92. The cover glass 92 was weighted down with a metal frame 93 (having a mass of 62.6 g). The metal frame 93 has, in this case, a window 94 for viewing the sample 90 through the cover glass 92. Thus, a sample image will be recorded of the sample 90 in a light microscope in black/white transmitted light at 100× magnification.

[0100] A 1 mm×1 mm square 95 of the sample image is randomly selected, and two diagonals 96, 97 are drawn into this square 95. The monofilament sections 98 intersected by the diagonals 96, 97 down to a measuring depth of 150 μm are measured by determining an equivalence diameter 99 (through circle equivalence). For this purpose, the top side of the pressed-down nonwoven is defined as the zero point. Nonwovens that are thinner than 150 μm can thus be covered in their entire thickness by means of this method. If monofilament sections are cut at the corners of the square, their equivalence diameter 99 can still be measured completely by means of circle equivalence.

[0101] The described measuring method can be repeated at two other nonwoven locations, and the average value can be determined across all equivalence diameters 99 of the monofilament sections 98 of those nonwoven locations. Multifilament sections and node points are disregarded in the measurement.

Description of the Examples:

[0102] Hereinafter, 7 examples (B1 to B7) of the nonwovens according to the invention will be shown.

[0103] The nonwovens (B1 to B7) mentioned as examples were produced according to a method comprising the following steps:

[0104] a lyocell spinning solution, including 10% cellulose, was prepared according to a known method described at the outset;

[0105] the spinning solution was extruded through closely adjacent openings of a spinneret arranged in series and was stretched in a blown air stream at a high velocity (for the process-technical details of the method, see the prior art mentioned at the outset);

[0106] during and/or after stretching, the cellulose was precipitated at least partially from the extruded spinning solution by applying a coagulant in order to form the molded bodies;

[0107] finally, the nonwoven was formed by placing the molded bodies onto a moving belt conveyor and subsequently washed and dried.

[0108] For demonstrating the advantageous characteristics according to the invention of the nonwovens produced in this way as regards their opacity, the blown air pressure (the velocity of the blown air stream) as well as the quantity of coagulation liquid were varied during the process as compared to a reference example (B4). It was possible to adapt the basis weight by specifically controlling the belt conveyor velocity. The parameters for the production of the examples B1 to B7 are summarized in Table 2.

TABLE-US-00002 TABLE 2 Production parameters for nonwovens according to the invention Blown air Coagulation pressure liquid Specific [compared to [compared to Basis weight opacity Example ref.] ref.] [g/m.sup.2] [% .Math. m.sup.2/g] B1 1 x 0.25 x 33.0 1.07 B2 1 x 0.50 x 61.2 1.12 B3 1 x 0.75 x 15.8 1.56 B4 - Ref. 1 x 1.00 x 23.6 1.66 B5 2 x 1.25 x 15.2 1.92 B6 2 x 1.50 x 18.2 1.93 B7 2 x 1.75 x 15.6 2.19

[0109] The thus obtained examples B1 to B7 consist of 100% cellulose, that is, of regenerated lyocell molded bodies, each having a specific opacity greater than 1%.Math.m.sup.2/g and a basis weight less than 70 g/m.sup.2.

[0110] In general, it was found that by specifically controlling the blown air stream (particularly, the velocity of the blown air stream by changing the pressure), a variation of the diameter distribution in the monofilament sections was obtained, wherein higher blown air stream velocities or a higher blown air pressure led to greater stretching and thus finer average diameters of the monofilament sections. Also, by varying the quantity of coagulation liquid applied to the extruded spinning dope, it was possible to influence the formation of monofilaments and thus the specific opacity of the nonwoven. In this connection, an increase of the quantity of coagulation liquid brought about a higher content of monofilament sections, which in turn led to a higher specific opacity.

[0111] The parameters (air pressure and quantity of coagulation liquid) in Table 2 were specified as factors related to the reference example B4. Here, the reference parameters for the reference example B4 were determined by adjusting the production plant such that a nonwoven with an average basis weight of 25 g/m.sup.2 ±10% and an average specific opacity of 1.6%.Math.m.sup.2/g±10% was obtained.

[0112] The specific opacity of the nonwovens B1 to B7 was determined according to the above-described measuring method. The measured values determined in this process are shown in Table 3.

TABLE-US-00003 TABLE 3 Measured values for nonwovens according to the invention Basis Specific Exam- Reflection Reflection Opacity Weight weight opacity ple black white [%] [g] [g/m.sup.2] [% .Math. m.sup.2/g] B1 29.36 83.09 35.33 0.330 33.0 1.07 B2 57.80 84.45 68.44 0.612 61.2 1.12 B3 20.35 82.82 24.57 0.158 15.8 1.56 B4 32.46 83.06 39.08 0.236 23.6 1.66 B5 24.23 82.88 29.23 0.152 15.2 1.92 B6 29.19 83.22 35.08 0.182 18.2 1.93 B7 28.34 82.98 34.16 0.156 15.6 2.19

Comparison Examples:

[0113] In order to illustrate the advantageous characteristics of Examples B1 to B7, Table 4 shows Comparison Examples V1 to V4. The basis weight and the specific opacity of the comparison examples were determined according to the afore-described measuring method.

TABLE-US-00004 TABLE 4 Characteristics of the comparison examples Specific Exam- Production Basis weight opacity ple Material method [g/m.sup.2] [% .Math. m.sup.2/g] V1 100% carding, 32.0 0.74 polypropylene thermobonding V2 100% lyocell carding, hydro- 79.7 0.88 entangling V3 100% cupro spunbonding 40.5 0.98 V4 100% polyester spunbonding 19.0 1.51

[0114] Comparison Example V1 is a carded, thermobonded nonwoven of 100% polypropylene fibers of the Sawabond 4138 type obtained from Sandler AG. The nonwoven has a low basis weight of 32 g/m.sup.2, however, exhibited low a specific opacity of only 0.74%.Math.m.sup.2/g in the measurement.

[0115] Comparison Example V2 is a carded, hydroentangled nonwoven of 100% lyocell staple fibers obtained from Lenzing AG. The nonwoven has a comparatively high basis weight of 79.7 g/m.sup.2, however, it still reaches a specific opacity of only 0.88%.Math.m.sup.2/g.

[0116] Comparison Example V3 is a 100% cupro sponbonded nonwoven from Asahi Kasei Corp. of the Bemliese SE384G type. At a basis weight of 40.5 g/m.sup.2, the spunbond is able to reach a specific opacity of only 0.98%.Math.m.sup.2/g.

[0117] Comparison Example V4 shows a 100% polyester spunbonded nonwoven of the Reemay 2250 type from Berry Global Inc. The polyester spunbonded nonwoven exhibits excellent specific opacity of 1.51%.Math.m.sup.2/g at a low basis weight of 19.0 g/m.sup.2.

[0118] In the scatter chart 50 of FIG. 3, the Comparison Examples V1 to V4 are shown as measured values 61, 62, 63, and 64, respectively, and related to the measured values 60 of the inventive Examples B1 to B7.