ABSORBENT PRODUCT COMPRISING FOAM MATERIAL

Abstract

Absorbent product includes a liquid permeable topsheet, a liquid impermeable backsheet, and an absorbent core enclosed between the topsheet and the backsheet, wherein the absorbent core includes a liquid inlet foam material located closest to the liquid pervious topsheet and an absorbent fibrous layer located closest to the impervious backsheet. The liquid inlet foam material has in the transversal direction of the absorbent product two edge regions and one central region located between the edge regions. The central region has a plurality of openings formed from a plurality of slits extending in the longitudinal direction of the absorbent product and that openings have been formed from the slits by expanding the continuous liquid inlet foam material in the transversal direction of the product, and that each edge region of the liquid inlet foam material has a width that is at least 5.0 mm and is free from openings.

Claims

1. An absorbent product comprising: a liquid permeable topsheet; a liquid impermeable backsheet; and an absorbent core enclosed between the topsheet and the backsheet, wherein the absorbent core comprises: a liquid inlet foam material located closest to the liquid pervious topsheet, and an absorbent fibrous layer located closest to the impervious backsheet, wherein the liquid inlet foam material in the transversal direction of the absorbent product has two edge regions and one central region located between the edge regions, wherein the central region has a plurality of openings formed from a plurality of slits extending in the longitudinal direction of the absorbent product, the openings have been formed from the slits by expanding the continuous liquid inlet foam material in the transversal direction of the product, and each edge region of the liquid inlet foam material has a width that is at least 5.0 mm and is free from openings.

2. The absorbent product according to claim 1, wherein the continuous liquid inlet foam material sheet has been extended to the same degree across its whole length.

3. The absorbent product according to claim 1, wherein the liquid inlet foam material, has been extended 30% to 200% from the original length of the unexpanded liquid inlet foam material.

4. The absorbent product according to claim 1, wherein the slit length is 5.0-20.0.

5. The absorbent product according to claim 1, wherein the most narrow width of the edge region is between 5.0 and 15.0 mm.

6. The absorbent product according to claim 1, wherein the openings have a longer dimension in the longitudinal direction of the absorbent product than in the transversal direction of the absorbent product.

7. The absorbent product according to claim 1, wherein the width of the openings in the transversal direction of the absorbent product may be 0.3 to 1.0 of the length of the openings in the longitudinal direction of the absorbent product.

8. The absorbent product according to claim 1, wherein the foam material is hydrophobic.

9. The absorbent product according to claim 1, wherein the distance between the openings is 1.5 to 5.0 mm.

10. The absorbent product according to claim 1, wherein the total open area formed by the plurality of openings in the central area in the horizontal plane is 40% to 70% of the total area of the liquid inlet foam material in the horizontal plane in the central area.

11. The absorbent product according to claim 1, wherein the liquid inlet foam material has substantially the same extension in the horizontal plane as the absorbent product.

12. The absorbent product according to claim 1, wherein at least one layer in the absorbent fibrous core has a density greater than 100 kg/m.sup.3.

13. The absorbent product according to claim 1, wherein a nonwoven and/or tissue layer is located between the liquid inlet foam material and the absorbent fibrous layer.

14. The absorbent product according to claim 13 wherein the nonwoven and/or tissue layer and the liquid inlet foam material have different colors.

15. The absorbent product according to claim 1, wherein the product furthermore comprises a front part, a back part and a crotch part located between the back part and the front part, wherein at least one layer of the absorbent core extends in the longitudinal direction of the product over the crotch part and at least a portion over the front part and it has a width in the transition between the crotch part and the front part which is less than 40 mm, and the side edges of the liquid-absorbent, fibrous layer diverge in the direction from the transition between the crotch part and the front part to at least a portion over the front part.

16. The absorbent product according to claim 1, wherein the liquid inlet foam material is laminated to a carrier material in its expanded condition so that the liquid inlet foam material is fixed to the carrier material in its expanded condition.

17. The absorbent product according to claim 16, wherein the carrier material is the top sheet or part thereof, and the liquid inlet foam material is facing the absorbent fibrous layer.

18. The absorbent product according to claim 16, wherein the carrier material is facing the absorbent fibrous layer of the absorbent core and the liquid inlet foam material is facing the top sheet.

Description

BRIEF DESCRIPTION OF FIGURES

[0037] FIG. 1A shows a top view of a liquid inlet foam material according to an embodiment of the invention before it has been expanded.

[0038] FIG. 1B shows a top view the liquid inlet foam material according to FIG. 1A after it has been expanded, i.e. after the slits have been opened to form openings.

[0039] FIG. 2 shows a cross-sectional view of a sanitary napkin according to an embodiment of the invention.

[0040] FIG. 3 shows the sanitary napkin of FIG. 2, seen from the side which will be facing the user when it is worn.

DETAILED DESCRIPTION OF THE FIGURES

[0041] FIG. 1A shows a top view of a liquid inlet foam material according to an embodiment of the invention after it has been slitted but before it has been expanded. FIG. 1A shows a top view of the liquid inlet foam material 1 after provision of longitudinal slits 2. The slits 2 in FIG. 1A are straight, but may have any suitable shape such as for example wave-shaped. The slits 2 are provided in staggered rows extending in the longitudinal direction of the inlet material 1 having a slit length A of 5-20 mm. The liquid inlet material 1 has in its transversal direction a central region 4 with slits and two edge regions 5, 6 without slits.

[0042] FIG. 1B shows a top view of the liquid inlet foam material 1 according to FIG. 1A after it has been expanded in the direction transversal to the slit 2 direction, i.e. after the slits 2 have been opened to form openings 3.

[0043] FIG. 2 shows a cross-sectional view of the different layers in the sanitary napkin according to an embodiment of the invention. The sanitary napkin 100 includes a liquid permeable topsheet 7, a liquid impermeable backsheet 8, and an absorbent core 11 enclosed between the topsheet 7 and the backsheet 8. The absorbent core 11 includes a liquid inlet foam material 1 arranged directly below the topsheet 7, an absorbent fibrous layer 9 directly above the backsheet 8, and a liquid pervious layer of nonwoven and/or tissue 10 enclosed between the liquid inlet foam material and the fibrous absorbent core. The sanitary napkin 100 has in its longitudinal direction a front end part 15, a back end part 17 and a crotch part 16 intermediate the front end part 15 and the back end part 17. The crotch part 16 is a portion which is intended to be placed against the crotch of a wearer during use of the product and to constitute the main acquisition area for body fluid that reaches the incontinence shield 100. The liquid inlet foam material 1 is located along the whole length of the sanitary napkin 100.

[0044] The topsheet 7 and the backsheet 8 of the sanitary napkin 100 extend together laterally outside of the absorbent core 11 along the whole circumference of the absorbent core 11. The topsheet 7 includes any material which is suitable for the purpose, i.e. soft and liquid pervious. Examples of commonly found topsheet 7 materials are nonwoven materials, perforated plastic films, plastic or textile mesh, and fluid permeable foam layers. Laminates including two or more topsheet materials are also commonly employed, as are top sheets including different materials within different parts of the fluid permeable wearer-facing surface.

[0045] The backsheet 8 is fluid impermeable. However, backsheet materials that are only fluid repellant may be used particularly in instances where relatively small amounts of urine are expected to be taken up. The backsheet 8 is commonly constituted by a thin, flexible, fluid-impermeable plastic film, but fluid-impermeable nonwoven materials, fluid impermeable foams and fluid impermeable laminates are also contemplated within the scope of the invention. The backsheet 8 may be breathable, implying that air and/or vapor may pass through the backsheet 8. Furthermore, the backsheet 8 may have an outer, garment-facing surface of a textile material such as nonwoven.

[0046] The absorbent fibrous layer 9 may be made up of any suitable absorbent or fluid uptake material as known in the art, such as one or more layers of cellulose fluff pulp, fibre waddings, etc. The absorbent fibrous layer 9 may also contain particles of highly absorbent polymer material, commonly known as superabsorbents, which are materials having the ability to absorb and retain large quantities of fluid upon formation of a hydrogel. The superabsorbents may be mixed with cellulose fluff pulp and/or may be arranged in pockets or layers in the absorbent fibrous layer 9. The fibres may be pulp fibres and the superabsorbent material may be polyacrylate-based particles.

[0047] The absorbent core 11 may further incorporate components for improving the properties of the absorbent core 11. Some examples of such components are binder fibers, fluid-dispersing materials, wetness indicators etc., as known in the art. The sanitary napkin 100 has an elongate, generally rectangular shape when fully extended in all directions. Any suitable shape may be used for the absorbent product, such as hourglass shape, trapezoidal shape, etc.

[0048] The sanitary napkin has a transversal rear end edge 14 intended to be orientated rearwards during use of the absorbent article, and a front end edge 13 intended to be facing forwards towards the abdomen of the wearer. The sanitary napkin 100 may further include fastening means for fastening of the absorbent product inside a supporting pant garment, such as a pair of underpants. The fastening means may be in the form of two longitudinally extending bands of pressure sensitive adhesive arranged on the garment-facing surface of the backsheet 8. The fastening means can be covered by a releasable protective layer, e.g. a siliconized paper, a nonwoven or any other releasable material as is known in the art. Before placing the absorbent product in the supporting pant garment, the protective layer is removed from the fastening means to expose the adhesive and make it available for fastening to the pant garment.

[0049] The fastening means is optional and may be omitted. When using an adhesive fastening means, any suitable adhesive pattern may be used such as full coating of the backsheet, one or more longitudinal adhesive band, transverse bands, dots, circles, curves, stars, etc.

[0050] The inlet material 1 in FIG. 2 is situated above the nonwoven layer 10 and beneath and in direct contact with the topsheet 7. The absorbent fibrous layer 9 of the sanitary napkin 100 is situated between the nonwoven layer 10 and the backsheet 8. The absorbent core 11 includes the liquid inlet foam material 1, the nonwoven layer 10 and the absorbent fibrous layer 9, however, the nonwoven layer 10 is optional. The absorbent core 11 may also include more absorbent layers. The absorbent layers may have uniform thickness or may vary in thickness in different parts of the layers. Similarly, the basis weight and composition may vary within the absorbent layers. By way of example, the absorbent fibrous layer 9 may include a mixture of absorbent and/or non-absorbent fibers and superabsorbent material, wherein the ratio of superabsorbent material to fibers may vary in the layer. The absorbent core 9 may have any suitable shape, such as an hourglass shape with widened end portions and a narrow portion in the crotch portion, or a rectangular shape. The inlet material 1 in the sanitary napkin 100 illustrated in FIGS. 2-3 has a rectangular shape. The absorbent fibrous layer 9 includes a shape like a keyhole. The liquid inlet foam material 1 has a rectangular shape. The absorbent fibrous layer 9 is intended to function as a stiffening element and is designed to reduce the risk that the sanitary napkin 100 deforms in an uncontrolled manner.

[0051] The liquid absorbent layer has a width M in the transition between the crotch part 16 and the front part 14 which width is less than 40 mm, or 30-35 mm. Both side edges of the front part 15 diverge in a forward direction in the product from this transition M. In this manner it is prevented that the product is shifted backwards between the user's legs.

[0052] In FIG. 2, there is an angle between a line in the longitudinal direction of the product and each of the side edges of the absorbent fibrous layer in the front part 15 designated with ?. In the case of a large angle ?, for example, in the vicinity of 90?, the edges of the front part can scrape against the users groins and legs, thus creating discomfort for the user. The smaller the angle ? is, the greater the risk that the product slides backwards in between the user's legs. At an angle below 30? this risk is unacceptably great. An angle between 35-45? gives the best balance between a firm hold and comfort.

[0053] FIG. 3 shows the sanitary napkin of FIG. 2, seen from the side which will be facing the user when it is worn.

[0054] The sanitary napkin 100 in FIGS. 2 and 3 is formed with a crotch length adapted to the user's anatomy. In a sanitary napkin in accordance with embodiments of the invention the fact was utilized that most women have a crotch length with a size of 80-100 mm. Along the crotch, where the user's body shape is substantially plane, the sanitary napkin is shaped so as to be relatively stiff laterally, i.e., it is sufficiently stiff so as to not be deformed laterally and form folds.

[0055] The width of the sanitary napkin in the crotch area is limited in front by the distance between the muscle sinews right in front of the user's groins. In the direction backwards from these transition areas to the end of the crotch part the width of the absorbent fibrous layer 9, that also functions as a stiffening element, can continuously increase to the size of 1.5 times the width M without the risk that the fibrous absorbent layer 9 scrapes the user in the crotch.

[0056] The absorbent fibrous layer 9 extends over the product's back part 17. The absorbent fibrous layer 9 has a recess 20 in the back part 17 and extending from its end edge and in the direction toward the crotch part 16 by means of which the product can fold along a longitudinally running line in the recess and by means of which the parts, the legs 21 and 22, that are located on both sides of the recess 20, become more flexible than the wider crotch part 16. This recess 20 is for obtaining a good adaptation to and pliability with the body. The fold which develops in the recess when the product is being used can pass into the user's posterior notch, thus offering a very good protection against leakage via the posterior notch, which type of leakage occurs when using sanitary napkins when the user is lying on her back. Furthermore, the recess 20 makes it possible that these legs 21, 22 can be mutually shifted vertically during various body movements, for example, when the user is walking.

[0057] In the exemplary embodiment shown in FIGS. 2 and 3 the recess 20 is wedge-shaped and symmetrically located relative to the longitudinally running line of symmetry L of the product and forms an angle ?. This angle can vary within broad limits but is of course dependent on the shape of the back part 17.

[0058] The sanitary napkin 100 described in FIGS. 2-4 is only one illustration of an absorbent product suitable for the present invention.

Examples

Pliability Measurement

[0059] The force that is required to shape a product to match the body after being applied to underwear is measured when the product is folded/bent in a fixture designed for the purpose. The force is defined as the resistance that occurs when the product, which is resting on a Teflon-covered lower fixture, is folded into the fixture by downward-moving metal wires in an upper fixture. The product rests freely on two horizontal, parallel, Teflon-covered supports. The sample is pressed down at the centreline of the product between the two supports using a tensile tester. The maximum force is registered.

Tested Products

[0060] The topsheet on the tested sanitary napkin has been a spunbond nonwoven with surface weight 22 g/m.sup.2. The absorbent core on the tested sanitary napkin has been a pulp core mixed with polyacrylate superabsorbent particles where the surface weight of the pulp has been 255 g/m.sup.2 and the surface weight of the superabsorbent has been 45 g/m.sup.2. The backsheet has been a film with a surface weight 21 g/m.sup.2.

[0061] Acquisition and distribution layer located between topsheet and absorbent core has been foam material according to following:

TABLE-US-00001 Foam A: P30900 from Recticel without slits B: P30900 from Recticel with slits C: P32250 from Recticel without slits D: P32250 from Recticel with slits

[0062] The slit length has been 10.0 mm. The slits have been provided in staggered rows extending in the longitudinal direction having a slit distance B between the ends of two mutually sequential slits in the staggered row and a row distance C between two adjacent rows.

Results

[0063]

TABLE-US-00002 Sanitary napkin Load (N) A (P30900 no slits) 4.7 B (P30900 with slits) 1.7 C (P32250 no slits) 3 D (P32250 with slits) 1.4

[0064] The result shows that the products with foam material with slits are more pliable.

Liquid Inlet Time

[0065] The method evaluates the ability of sanitary napkins to absorb large quantities of liquids which come in contact with the product over a short period of timeknown as splashes.

[0066] The inlet time is defined as that from the start of dosing 3 ml of artificial menstrual liquid until all the liquid is absorbed by the product.

[0067] The product is laid flat and exposed to dynamic pressure. The liquid is applied in one dose per product and the inlet time is registered by software.

[0068] The topsheet on the tested sanitary napkin has been a spunbond nonwoven with surface weight 22 g/m.sup.2. The absorbent core on the tested sanitary napkin has been a pulp core mixed with polyacrylate superabsorbent particles where the surface weight of the pulp has been 255 g/m.sup.2 and the surface weight of the superabsorbent has been 45 g/m.sup.2. The backsheet has been a film with a surface weight 21 g/m.sup.2.

[0069] The acquisition and distribution layer located between topsheet and absorbent core has been liquid inlet foam material according to following:

TABLE-US-00003 Foam E: MCF003 from Recticel no openings F: MCF003 from Recticel with openings G: T25090 from Recticel no openings H: T25090 from Recticel with openings I: XD4200A from Caligen no openings J: XD4200A from Caligen with openings

[0070] The slit length has been 10.0 mm. The slits have been provided in staggered rows extending in the longitudinal direction having a slit distance B between the ends of two mutually sequential slits in the staggered row and a row distance C between two adjacent rows. Openings have been formed from the slits by expanding the continuous liquid inlet foam material in the transversal direction of the product.

Result Inlet Time

[0071]

TABLE-US-00004 Product Inlet time (sec) E (MCF003 no slits) 11.1 F (MCF003 slits) 7 G (T25090 no slits) 20.3 H (T25090 slits) 10.7 I (XD4200A no slits) 32 J (XD4200A slits) 9.2

[0072] The result shows that the liquid inlet time is shorter with liquid inlet foam material with openings than liquid inlet foam material without openings.

Density, Thickness and Contact Angles

[0073] Density, thickness and contact angles have been measured on the foam material itself, so without openings. The density and the thickness have been measured with an applied pressure on the foam of 0.5 kPa. The contact angle has been measured with a DAT-equipment after 1 second.

[0074] The result is as follows:

TABLE-US-00005 Supplier Contact code Supplier Density(kg/m3) Thickness(mm) angle 1 MCF003 Recticel 81 2.1 87 2 T25090 Recticel 24 2.6 112 3 XD4200A Caligen 28 3.0 102 4 P30900 Recticel 38 3.2 below 90 5 P32250 Recticel 40 3.0 below 90