SANITARY ARTICLE

Abstract

A sanitary article comprises a fluid permeable surface layer and a backsheet. The backsheet is provided with an adhesive in at least one adhesive region arranged on an outwardly oriented side for attachment of the sanitary article to an undergarment on a user-facing side of the undergarment and at least one adhesive-free region arranged on the outwardly oriented side. The surface layer is an air-through-bonded fibrous nonwoven surface layer having a basis weight of from 14 to 30 g/m.sup.2 and a density of from 20 to 90 kg/m.sup.3. The adhesive-free region extends in the longitudinal direction and the transverse width of the adhesive-free region is from 7% to 40% of total transverse width of the backsheet, as measured at a widest transverse width of the backsheet in the rear portion.

Claims

1. A sanitary article having longitudinal side edges extending in a longitudinal direction and transverse front and rear end edges extending in a transverse direction, said sanitary article comprises a fluid permeable surface layer and a backsheet, said backsheet being provided with an adhesive in at least one adhesive region arranged on an outwardly oriented side for attachment of the sanitary article to an undergarment on a user-facing side of said undergarment and at least one adhesive-free region arranged on the outwardly oriented side, said backsheet being divided by an imaginary dividing line in a front portion and a rear portion as seen in the longitudinal direction, said front portion and said rear portion being of equal length and corresponding to portions of the backsheet intended to face the user-facing side of the undergarment during use, wherein said surface layer is an air-through-bonded fibrous nonwoven surface layer having a basis weight of from 14 to 30 g/m.sup.2 and a density of from 20 to 90 kg/m.sup.3, wherein the adhesive-free region extends in the longitudinal direction, and wherein the transverse width of the adhesive-free region is from 7% to 40% of a total transverse width of said backsheet, as measured at a widest transverse width of said backsheet in said rear portion.

2. A sanitary article according to claim 1, wherein the adhesive-free region is from 10% to 30% of the total transverse width (wT) of said backsheet, as measured at the widest transverse width of said backsheet in said rear portion.

3. A sanitary article according to claim 1, wherein the backsheet is provided with more than one adhesive region and more than one adhesive-free region, wherein each of the adhesive regions and each of the adhesive-free regions extend in the longitudinal direction, and wherein the transverse width of at least one adhesive-free region is from 7% to 40% of the total transverse width (wT) of said backsheet as measured at the widest transverse width of said backsheet in said rear portion.

4. The sanitary article according to claim 1, wherein said rear portion is divided, as seen in said transverse direction, in a central rear portion and in first and second lateral rear portions extending from said dividing line and towards said rear end edge, wherein said adhesive region covers said central rear portion forming a central rear adhesive region, and wherein said first and second lateral rear portions are free from adhesive.

5. The sanitary article according to claim 4, wherein a transverse width of said central rear adhesive region is from 10% to 70% of the total transverse width of said backsheet, as measured at the widest transverse width of said backsheet in said rear portion.

6. The sanitary article according to claim 4, wherein said adhesive-free first and second lateral rear portions extend from said dividing line and to said rear end edge and/or said central rear adhesive region extends from said dividing line and to said rear end edge.

7. The sanitary article according to claim 1, wherein said rear portion is divided, as seen in said transverse direction, in a central rear portion and in first and second lateral rear portions extending from said dividing line and towards said rear end edge, wherein said central rear portion is free from adhesive, and wherein said adhesive region covers said first and second lateral rear portions forming first and second lateral rear adhesive regions.

8. The sanitary article according to claim 7, wherein a transverse width of said first and second lateral rear adhesive regions each is from 5% to 40%, as measured at the widest transverse width of said backsheet in said rear portion.

9. The sanitary article according to claim 1, wherein the air-through-bonded fibrous nonwoven surface layer comprises bicomponent fibers.

10. The sanitary article according to claim 9, wherein said bi-component fibers are sheath-core bicomponent fibers, preferably wherein said core is a polyester core and said sheath is a polyethylene sheath.

11. The sanitary article according to claim 1, wherein said fibers of said air-through-bonded nonwoven have a coarseness of from 1.8 to 10 dTex.

12. The sanitary article according to claim 1, wherein said outwardly oriented side of said backsheet comprises a liquid impermeable plastic film.

13. The sanitary article according to claim 1, wherein said sanitary article comprises an intermediate layer located between said surface layer and said backsheet, said intermediate layer comprising a nonwoven material.

14. The sanitary article according to claim 13, wherein said intermediate layer covers from 70% to 100% of said surface layer.

15. The sanitary article according to claim 1, wherein at least said surface layer is embossed with an embossing pattern.

16. The sanitary article according to claim 1, wherein the sanitary article is a sanitary napkin.

17. The sanitary article according to claim 5, wherein the transverse width of said central rear adhesive region is from 10% to 40% of the total transverse width of said backsheet, as measured at the widest transverse width of said backsheet in said rear portion.

18. The sanitary article according to claim 1, comprising a thinner rear portion having a thickness of no more than 8 mm.

19. The sanitary article according to claim 18, wherein the thinner rear portion has a length of about 30% of a total length of the sanitary article measured from the rear end edge to the front end edge.

20. The sanitary article according to claim 15, wherein the embossing pattern covers from 3% to 20% of the surface layer.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0032] The present invention will be further explained hereinafter by means of non-limiting examples and with reference to the appended drawings wherein:

[0033] FIG. 1 shows a top plan view of a sanitary napkin as disclosed herein and as seen from a topsheet side;

[0034] FIG. 2 shows a top plan view of a sanitary napkin as disclosed herein and as seen from the backsheet side;

[0035] FIG. 3 shows a top plan view of an alternative sanitary napkin as disclosed herein and as seen from the backsheet side;

[0036] FIG. 4 shows friction measurement result on surface material.

DETAILED DESCRIPTION

[0037] The invention will be described more closely below by reference to an exemplary embodiment. The invention may however be embodied in many different forms and should not be construed as limited to the embodiments set forth in the drawings and the description thereto.

[0038] FIG. 1 is a top plan view of a sanitary article 1 having longitudinal side edges 2,3 extending in a longitudinal direction L and transverse front and rear end edges 4,5 extending in a transverse direction T. The sanitary article 1 comprising a fluid permeable surface layer 8 and a backsheet 9. The surface layer 8 is an air-through-bonded fibrous nonwoven surface layer having a basis weight of from 14 to 30 g/m.sup.2 and a density of from 20 to 90 kg/m.sup.3. The nonwoven layer comprises bicomponent fibers and may constitute of from 50% or more, such as 80% to 100% or from 95% or more, of bicomponent fibers. The bicomponent fibers may be sheath-core bicomponent fibers, preferably wherein the core is a polyester core and the sheath is a polyethylene sheath. The sanitary napkin 1 may include an absorbent core between the surface layer 8 and the backsheet 9.

[0039] The absorbent core may be of any conventional kind. Examples of commonly occurring absorbent materials are cellulosic fluff pulp, tissue layers, highly absorbent polymers (so called superabsorbents), absorbent foam materials, absorbent nonwoven materials or the like. It is common to combine cellulosic fluff pulp with superabsorbents in an absorbent structure. It is also common to have absorbent structures comprising layers of different material with different properties with respect to liquid acquisition capacity, liquid distribution capacity and storage capacity. This is well-known to the person skilled in the art and does therefore not have to be described in detail. The thin absorbent bodies, which are common in today's sanitary articles, often comprise a compressed mixed or layered structure of cellulosic fluff pulp and superabsorbent. The size and absorbent capacity of the absorbent structure may be varied to be suited for different uses such as sanitary articles, pantyliners, adult incontinence pads and diapers, baby diapers, pant diapers, etc.

[0040] The sanitary article 1 may be a thin sanitary article 1, having a first thickness of not more than 8 mm in a thinner rear portion, the thinner rear portion having a length of about 30% of the total length of the sanitary article 1.

[0041] The backsheet may consist of a thin plastic film, e.g. a polyethylene or polypropylene film, a nonwoven material coated with a liquid impervious material, a hydrophobic nonwoven material, which resists liquid penetration. Laminates of plastic films and nonwoven materials may also be used. The backsheet material may be breathable so as to allow vapor to escape from the absorbent structure, while still preventing liquids from passing through the backsheet material. Preferably the outwardly oriented side of the backsheet is a plastic film. A plastic film provides less friction against undergarment than a fibrous nonwoven material and thus promotes that the sanitary article conforms well to the body of the wearer.

[0042] FIG. 2 is a top plan view of the sanitary article 1, as seen from the backsheet 9, being the side intended to face a user-facing side of an undergarment during use. The backsheet 9 is divided by an imaginary dividing line 10 in a front portion 11 and a rear portion 12 as seen in said longitudinal direction L. The front portion 11 and the rear portion 12 are of equal length. The rear portion 12 is divided, as seen in the transverse direction T, in a central rear portion 12a and in first and second lateral rear portions 12b,12c extending from the dividing line 10 and towards the rear end edge 5. The backsheet 9 is provided with an adhesive in an adhesive region 13 arranged on an outwardly oriented side 14 thereof. The adhesive region 13 covers the central rear portion 12a forming a central rear adhesive region 22a and the first and second lateral rear portions 12b,12c are free from adhesive. The adhesive is an adhesive conventionally used on backsheets for sanitary napkins for securing the sanitary napkin to the undergarment of the user. A transverse width w.sub.1 of the central rear adhesive region 13a is from 10% to 70%, optionally from 10% to 40%, of a total transverse width w.sub.T, i.e. w.sub.1+w.sub.2+w.sub.3, of the backsheet 9, as measured at a widest transverse width of said backsheet 9 in said rear portion 12.

[0043] The adhesive-free first and second lateral rear portions 12b,12c and the central rear adhesive region 13a each extends from the dividing line 10 and to the rear end edge 5. However, the central rear adhesive region 13a may also extend close to the rear end edge 5, such as for example up to 10 mm from the rear end edge 5.

[0044] The front portion 14 is provided with adhesive in the adhesive region arranged in a central front region. However, the front region may have an adhesive region extending over the entire regions or only parts thereof.

[0045] FIG. 3 is a top plan view of an alternative sanitary napkin 1 according to the present disclosure. The sanitary napkin 1 is shown from a backsheet 9 side. The backsheet 9 is divided by an imaginary dividing line 10 in a front portion 11 and a rear portion 12 as seen in said longitudinal direction L. The front portion 11 and the rear portion 12 are of equal length. The rear portion 12 is divided, as seen in the transverse direction T, in a central rear portion 12a and in first and second lateral rear portions 12b,12c extending from the dividing line 10 and towards the rear end edge 5. The backsheet 9 is provided with an adhesive in an adhesive region 13 arranged on an outwardly oriented side 14 thereof. The adhesive region 13 covers the first lateral rear portion 12b and the second lateral rear portion 2c, thereby forming a first lateral rear adhesive region 13b and second lateral rear adhesive region 13c. The central rear portion 12a is free from adhesive. The adhesive is an adhesive conventionally used on backsheets for sanitary napkins for securing the sanitary napkin to the undergarment of the user. A transverse width of each of the first and second lateral rear adhesive regions 13b,13c may be from 5% to 40%, as measured at a widest transverse width of the backsheet 9 in the rear portion 12. The transverse width of the backsheet is measured on the part of the sanitary napkin 1 facing the wearer facing side of an undergarment. Thus, for a sanitary napkin provided with lateral wings, these are not to be included for such measurements.

[0046] The sanitary napkin is provided with a pair of lateral wings 16a,16b extending outward from the transversely opposite side edges 2,3 of the napkin. The wings are provided with attachment means, such as with an adhesive, on their garment facing surface so that the wings 16a, 16b can be folded back under the undergarment and attached to the garment facing side of the undergarment. In this way, the wings 16a, 16b serve to keep the napkin 1 properly positioned in the undergarment.

[0047] FIG. 4 shows three friction curves, the test sample according to the present invention, and two comparative examples, CEx 1 and CEx 2. These samples are described more in detail in table 1. In FIG. 4 is the number of runs on the x-axis and the friction force in gmf on the y-axis. In FIG. 4 is the number of runs on the x-axis and the friction force in gmf on the y-axis. A friction curve comprises a first slope having a positive coefficient illustrating increase in the friction values, a plateau, and a second slope having a negative coefficient illustrating decrease in friction values. At the plateau, the friction values are substantially constant over the extension of the plateau. Small variations at the plateau as well as along the slopes are possible between individual values, but with a positive coefficient is meant that all individual values in the first slope together creates a positive coefficient, as well as all individual values in the second slope together creates a negative coefficient, as well as all individual values in the plateau together creates a plateau. Lower friction values render the absorbent article more skin friendly and skin problems arising with the use of the absorbent article can be reduced. For some materials a clear peak can be seen in a curve of friction values before the second slope creating a negative coefficient. Such a peak is caused by clinging, which may occur when only a small amount of moisture is present. The result shows that the test sample (air-through-bonded nonwoven surface material) has a lower mean friction plateau value (gmf) than the two comparative examples CEx 1 and CEx 2.

[0048] Friction Measurement—Stick and Slip Method for Measuring the Wet Friction

[0049] Friction occurring between a nonwoven material and the skin of the user is different in the presence of liquid/moisture than when no liquid/moisture is present. Even a very small amount of moisture present originating from perspiration, sweat or other body fluids has an impact on the friction forces occurred between the nonwoven material and the skin of the user. It has therefore been discovered that it is really important to carefully choose the nonwoven characteristics, so that the nonwoven is able to minimize the mechanical discomfort during the overall use of the product.

[0050] The method used is called Stick and slip measurement method for measuring the wet friction and the method measures the static friction, sns value (stick and slip value) in gram force, gmf, between a material and the human skin. Repeatedly runs are made using the same material strip. First the sns value for the dry state (dry material and skin) is measured followed by wet state at different liquid levels (from completely wetted material, to moist and to almost dry) until the sns value is back to the skin-material interaction level measured in the first dry run, which mean that the material is dry again. The method is thus called a repeated stick and slip method or sns dry-wet-dry. The stick and slip value is defined as the point on the force curve (gmf) where the material starts gliding over the arm. The sns values from all single force curves are then put together in a new graph, sns values as a function of number of runs.

[0051] Three different nonwoven materials were tested and compared in terms of dry friction and wet friction. The test material is an air-through-bonded nonwoven according to the present disclosure comprising bicomponent fibers of core-sheath type with a polyester core and a polyethylene sheath. The first Comparative Example is a spunbond nonwoven with polypropylene fibers and the second Comparative Example is spunbond nonwoven with polypropylene fibers. Table 1 below provides specifications of the materials tested.

TABLE-US-00001 TABLE 1 Material Material Basis weight Type Supplier no (gsm) Test sample Air-though TWE 255272 20 bonded nw CEx 1 Spunbond Texbond 2436701 18 nonwoven CEx 2 Spunbond Union 272119 18 nonwoven

[0052] In Table 2 below shows result of the mean friction plateau values measured in gmf. By gmf is meant gram-force and one gram-force is 9.80665 mN and the result shows that the test sample, the air-through-bonded nonwoven surface material has a lower mean friction plateau value (gmf) than CEx 1 and CEx 2. Also in FIG. 4 shows the friction curves for test sample, CEx 1 and CEx2. The air through bonded nonwoven has a lower friction than the spunbonded nonwoven materials.

TABLE-US-00002 TABLE 2 Material Mean friction plateau value, (gmf) Test sample 300 CEx 1 480 CEx 2 420

[0053] Initial Spreading Measurement

[0054] The initial spreading for a surface layer material according to the present disclosure was compared with a conventional spunbond surface layer 20 g/m.sub.2. The method used was the FLOW method and a sanitary napkin according to the present invention and comprising an air through bonded nonwoven 20 g/m.sub.2 from TWE, as surface layer and combined with an intermediate layer in the form of an airlaid nonwoven material having a basis weight of 65-70 g/m.sub.2, was compared with a sanitary napkin comprising a surface layer of a spunbonded nonwoven material combined with an intermediate layer in the form of an airlaid nonwoven material 65-70 g/m.sub.2. The test articles included also a pulp core layer and a liquid impermeable polyolefin plastic film backsheet. Each of the test articles included exactly the same layers except for the surface layer.

[0055] The test samples are conditioned in 24±4 h at 50±10% r.h. and 23±1° C. The number of samples for each test type is 6. The samples are placed on a Plexiglas table with an angle of 25°.

[0056] According to the FLOW method, 5 ml of test liquid, synthetic menstrual fluid, is added to the sanitary napkins provided with the respective materials as surface layers, the test liquid is added in a dose 1, 2 and 3 with an interval of 15 seconds and with a flow speed of 20 ml/min. After this the spreading length (mm) of the liquid was measured for each of the materials and is shown in the table 3 below. When the fluid has been added, the longest distance the fluid has run on top of the surface material is measured.

TABLE-US-00003 TABLE 3 Test sample CEx 2 (spunbond (air-through-bonded nonwoven nonwoven material) material) Dose 1 51 mm  71 mm Dose 2 74 mm  88 mm Dose 3 94 mm 113 mm

[0057] As illustrated in table 3, the spreading length of the liquid and thereby the wetted surface area is lower for the air-through-bonded nonwoven material. Details regarding the surface fibrous nonwoven surface layers can be seen in Table 1.

[0058] Density Measurement

[0059] The density is calculated by dividing the basis weight of the fibrous nonwoven surface layer by its thickness measured at a pressure of 0.5 kPa. The thickness is determined by means of a measuring foot with affixed load of 0.5 k Pa having a foot area of 50×50 mm.sup.2. The thickness is read off at the digital thickness gauge/tester after 10 seconds when the measuring foot has touched the surface of the sample.

[0060] Embossing Measurement

[0061] The depth of the individual embossed elements in the form of dots have been measured by the method ISO25178 and also the depth of a continuous embossed line extending along a contour of the absorbent sanitary napkin framing the embossed pattern comprising the individual embossed elements have been measured by the method ISO25178. Three different sanitary napkins were tested having different surface layers but otherwise constructed with the same underlying materials and compared in terms of diversity of embossment depth. The test material is an air-through-bonded nonwoven according to the present disclosure comprising bicomponent fibers of core-sheath type with a polyester core and a polyethylene sheath. The first Comparative Example is a spunbond nonwoven with polypropylene fibers and the second Comparative Example is spunbond nonwoven with polypropylene fibers (for details about the material see Table 1). In Table 4 shows the result of the mean individual depth of the individual embossed elements (μm) and the standard deviation of the depth (μm).

TABLE-US-00004 TABLE 4 Mean individual Standard depth (μm) deviation (μm) Test sample (air-through 388 5.9 bonded nonwoven) CEx 1 (spunbond 446 26.0 nonwoven) Cex 2 (spunbond 368 22.3 nonwoven)

[0062] The result shows that the standard deviation of the depth value of the embossment element for the air-through-bonded nonwoven was lower than the standard depth deviation for the comparative examples, Cex 1 and Cex 2.

TABLE-US-00005 TABLE 5 The depth of a continuous embossed line, a “valley” The depth of a continuous embossed line has also been measured by the method ISO25178. Ratio between Mean Standard Standard deviation individual deviation and Mean individual depth (μm) (μm) depth Test sample 971 148 0.15 CEx 1 597 204 0.34 Cex 2 442 91 0.21

[0063] The mean individual depth of a continuous embossed line, a “valley”, for the air-through-bonded nonwoven surface layer according to the Test sample, has a lower ratio between Standard deviation and Mean individual depth than the Comparative example 1 (Cex 1) and the Comparative example 2 (Cex 2). So, both the standard deviation of the mean depth of the individual embossed elements in the form of dots, and the ratio between Standard deviation and Mean individual depth of a continuous embossed line shows that the air-through-bonded nonwoven surface material resulting in more distinct embossed elements that enhances the visibility of the embossing pattern when provided on the material.