JP2023097914A - absorbent article - Google Patents

Abstract

An object of the present invention is to improve liquid diffusibility and suppress liquid return.
An absorbent core (4) has an absorbent body (41) in which a superabsorbent material (413) is fixed between an upper absorbent sheet (411) and a lower absorbent sheet (412). In the absorbent body, material-existing regions 42 to which the superabsorbent material is fixed are arranged with gaps in the width direction, and material-existing regions in which the superabsorbent material is not present are present between adjacent material-existing regions. 43 is provided. In each material absent region, the upper absorbent sheet and the lower absorbent sheet are generally joined. When focusing on a predetermined range in the longitudinal direction, the top sheet 21 and the upper absorbent sheet are non-joined over the entire predetermined range in the non-material region 43a in the center in the width direction, and the material in the center is non-bonded. The top sheet and the upper absorbent sheet are joined in the material existing areas on both sides of the existing area. The load when the nonwoven fabric of the top sheet is stretched by 3% in the width direction is greater than the load of the nonwoven fabric of the upper absorbent body sheet.
[Selection drawing] Fig. 6

Description

The present invention relates to absorbent articles.

Conventionally, absorbent articles such as disposable diapers have been used. In such an absorbent article, an absorbent core containing a superabsorbent material is arranged in a portion that receives urine, etc. from the wearer to improve the absorption capacity. For example, in the absorbent article of Patent Literature 1, an absorbent mat (absorbent core) having a sheet-like water absorbent layer containing water absorbent resin powder and a fiber assembly layer containing pulp fibers is provided. In the sheet-like water-absorbent layer, the water-absorbent resin powder is included between a plurality of nonwoven fabric sheets. The sheet-like water-absorbent layer has a water-absorbent resin powder-present region and a water-absorbent resin powder-absent region, and the non-woven fabric sheet is joined in the water-absorbent resin powder-absent region to form a sealing portion. In Patent Document 1, when the water-absorbing resin absorbs body fluid and swells, a gap is generated between the fiber assembly layer and the sealing portion. As a result, the bodily fluid that seeps out of the fiber assembly layer is diffused through the voids, preventing the liquid from returning (liquid return).

In addition, in the absorbent article of Patent Document 2, the fiber assembly layer of the absorbent mat is composed of upper and lower two layers of fiber assembly, and the upper fiber assembly is provided with openings. By locating the water-absorbing resin powder-free region of the sheet-shaped water-absorbing layer above the opening, the body fluid excreted by the wearer passes through the water-absorbing resin powder-free region and the opening to the lower fibers. lead to the collective. This speeds up the absorption rate. Patent Documents 3 and 4 describe joining the top sheet and the absorbent body with an adhesive.

Japanese Patent No. 4502586 Japanese Patent No. 4416441 JP 2008-149017 A JP-A-2001-17470

As described above, in the absorbent article of Patent Document 1, since a gap is formed between the fiber assembly layer and the sealing portion, liquid diffusion is improved and liquid return is suppressed, but it is not necessarily sufficient. isn't it. Therefore, there is a demand for a novel technique capable of improving liquid diffusibility and suppressing liquid return.

The present invention has been made in view of the above problems, and an object of the present invention is to improve liquid diffusibility and suppress liquid return.

The invention according to claim 1 is an absorbent article for receiving excrement from a wearer, comprising a liquid-permeable top sheet, a water-repellent or liquid-impermeable back sheet, the top sheet and the back. a longitudinally extending absorbent core disposed between the sheets, said absorbent core comprising an absorbent body having superabsorbent material secured between upper and lower absorbent sheets; In the absorbent body, a plurality of material existing regions to which the superabsorbent material is fixed are arranged with a gap in the width direction, and between two material existing regions adjacent to each other in the width direction, the superabsorbent A material non-existing region is provided in which no material is present, and in each material non-existing region, the upper absorbent sheet and the lower absorbent sheet are entirely joined to prevent urination from the wearer in the longitudinal direction. When focusing on the predetermined range to receive the material, the top sheet and the upper absorbent sheet are not bonded to each other over the entire predetermined range in the widthwise central non-material area, and the central material The top sheet and the upper absorbent sheet are joined in each of the two material-existing regions adjacent to the non-existing region on both sides in the width direction, and the non-woven fabric forming the top sheet is stretched three times in the width direction. The load when stretched by 3% is greater than the load when the nonwoven fabric forming the upper absorbent sheet is stretched by 3% in the width direction.

The invention according to claim 2 is the absorbent article according to claim 1, wherein the load when the nonwoven fabric forming the top sheet is stretched by 3% in the width direction forms the upper absorbent sheet. It is 2.0 times or more the load when the nonwoven fabric is stretched 3% in the width direction.

The invention according to claim 3 is the absorbent article according to claim 1 or 2, wherein the fineness of the nonwoven fabric forming the top sheet is 1.1 times the fineness of the nonwoven fabric forming the upper absorbent sheet. more than double.

The invention according to claim 4 is the absorbent article according to any one of claims 1 to 3, wherein the basis weight of the nonwoven fabric forming the top sheet is that of the nonwoven fabric forming the upper absorbent sheet. It is 1.1 times or more of the basis weight.

The invention according to claim 5 is the absorbent article according to any one of claims 1 to 4, wherein the compressibility under a predetermined load of the nonwoven fabric forming the top sheet is is less than the compressibility of the nonwoven fabric forming the

The invention according to claim 6 is the absorbent article according to any one of claims 1 to 5, wherein the absorbent core is disposed between the absorbent body and the back sheet, and has a sheet-like shape. It further comprises another absorbent body having a fiber assembly of

The invention according to claim 7 is the absorbent article according to claim 6, wherein the another absorbent body has a concave portion recessed toward the back sheet on the surface in contact with the absorbent body. , the recess extends at least over the predetermined range in the longitudinal direction and overlaps the central material absent area and the two material present areas on both sides of the central material absent area.

ADVANTAGE OF THE INVENTION According to this invention, while liquid diffusibility is improved, a liquid return can be suppressed.

1 is a plan view showing an absorbent article; FIG. 1 is a cross-sectional view showing an absorbent article; FIG. It is a top view which shows a main-body part. It is sectional drawing which expands and shows an absorption core. FIG. 4 is a diagram for explaining joining of the upper absorbent sheet and the top sheet; Fig. 2 is a cross-sectional view showing an absorbent core with swollen superabsorbent material;

FIG. 1 is a plan view showing an absorbent article 1 according to one embodiment of the present invention in an unfolded state. The absorbent article 1 is an auxiliary absorbent pad that is attached to the inside (that is, the wearer's side) of an exterior article such as a disposable diaper worn by the wearer and receives excrement such as urine from the wearer. In FIG. 1, the absorbent article 1 is drawn with the side that contacts the wearer when worn facing forward.

FIG. 2 is a cross-sectional view of the absorbent article 1 cut along a plane perpendicular to the longitudinal direction (vertical direction in FIG. 1) at the position II-II shown in FIG. As shown in FIGS. 1 and 2, the absorbent article 1 includes a substantially sheet-like body portion 2 and a pair of side sheets 3 . The body portion 2 includes a liquid-permeable top sheet 21, a water-repellent or liquid-impermeable back sheet 23, and a substantially sheet-like absorbent core 4 disposed between the top sheet 21 and the back sheet 23. Prepare. In FIG. 2, each component of the absorbent article 1 is drawn separated in the thickness direction for convenience of illustration. In addition, in FIG. 1, the outline of the absorbent core 4 is drawn with a thick dashed line for easy understanding of the drawing.

As shown in FIG. 1, the absorbent core 4 and the main body portion 2 are substantially rectangular in shape extending in the longitudinal direction in plan view. Specifically, the absorbent core 4 and the main body 2 have a so-called hourglass shape in which the width of both ends in the longitudinal direction is greater than the width of the central portion. The outer shape of the absorbent core 4 is the outer shape of the lower layer absorbent body 46 described later. The body portion 2 is slightly larger than the absorbent core 4 , and the entirety of the absorbent core 4 is located inside the outer peripheral edge of the body portion 2 . The outer shape of the main body part 2 is the outer shape of the back sheet 23 , and the length in the longitudinal direction and the width in the width direction of the back sheet 23 are larger than the length and width of the absorbent core 4 . As shown in FIG. 2, the top sheet 21 covers the main surface of the absorbent core 4 on the wearer side. The backsheet 23 covers the other major surface of the absorbent core 4, ie, the major surface opposite to the wearer. In this embodiment, the top sheet 21 is substantially rectangular (see FIG. 3 described later), and is joined to the back sheet 23 via a hot-melt adhesive or the like outside the absorbent core 4 in the longitudinal direction.

The top sheet 21 is a liquid-permeable sheet member, which quickly captures the moisture of the wearer's excrement and transfers it to the absorbent core 4 . The absorbent core 4 absorbs moisture permeating through the top sheet 21 and quickly fixes it. The back sheet 23 prevents water and the like of excrement reaching the back sheet 23 from seeping out of the main body 2 . Details of the structure of the absorbent core 4 will be described later.

As shown in FIGS. 1 and 2, the pair of side sheets 3 are arranged on both sides of the main body 2 (that is, on both sides in the width direction perpendicular to the longitudinal direction), and are approximately the entire length of the main body 2 in the longitudinal direction. over. Each side seat 3 includes a side seat body 31 and side wall elastic members 32 . As shown in FIG. 2 , the side seat main body 31 includes a fixing portion 33 and side wall portions 34 . The fixing portion 33 extends over approximately the entire length of the body portion 2 in the longitudinal direction on the side portion of the body portion 2 . The fixing portion 33 is fixed on the side portion of the main body portion 2 . Fixing between the fixing portion 33 and the main body portion 2 is performed via an adhesive such as a hot-melt adhesive.

The side wall portion 34 continues to the inner side in the width direction of the fixing portion 33 and extends in the longitudinal direction together with the fixing portion 33 . The side wall portions 34 are overlapped on the main body portion 2 at both ends in the longitudinal direction and fixed with a hot-melt adhesive or the like. In the absorbent article 1 , a pair of side wall portions 34 are provided on the top sheet 21 side in the vicinity of both side portions of the absorbent core 4 . A side wall elastic member 32 extending in the longitudinal direction is joined in a stretched state to the end of each side wall 34, that is, the free end, with a hot-melt adhesive or the like. The sidewall elastic member 32 includes at least one longitudinally extending elastic element. Contraction of the side wall elastic member 32 causes the side wall 34 to rise toward the wearer, forming three-dimensional gathers.

Polyolefin-based, rubber-based, and vinyl acetate-based adhesives are used as the above-mentioned hot-melt adhesives. The bonding between the top sheet 21 and the back sheet 23, the bonding between the side sheet 3 and the body portion 2, and the like may be performed by thermal fusion bonding, ultrasonic bonding, or the like. Also, the side wall elastic member 32 may be joined by ultrasonic joining or the like.

The top sheet 21 is made of, for example, a liquid-permeable nonwoven fabric. The nonwoven fabric is formed of, for example, hydrophobic fibers (polypropylene, polyethylene, polyester, polyamide, nylon, etc.) whose surface is hydrophilically treated with a surfactant. The nonwoven fabric may be made of hydrophilic fibers such as cellulose, rayon or cotton. The nonwoven fabric is, for example, an air-through nonwoven fabric, a point-bonded nonwoven fabric, a spunbonded nonwoven fabric, a spunlaced nonwoven fabric, or the like.

The back sheet 23 is, for example, a liquid-impermeable or liquid-repellent nonwoven fabric (spunbond nonwoven fabric, meltblown nonwoven fabric, SMS (spunbond-meltblown-spunbond) nonwoven fabric, etc.) formed of hydrophobic fibers, or an impermeable It is formed of a liquid or liquid repellent plastic film. The back sheet 23 may be a laminate of the nonwoven fabric and the plastic film. When a plastic film is used for the back sheet 23, a plastic film having moisture permeability (that is, breathability) is used from the viewpoint of preventing stuffiness of the absorbent article 1 and improving the wearer's comfort. preferably.

The side sheet main body 31 is formed of, for example, a liquid-impermeable or liquid-repellent nonwoven fabric (such as an air-through nonwoven fabric, a point-bonded nonwoven fabric, a spunbonded nonwoven fabric, a melt-blown nonwoven fabric, or an SMS nonwoven fabric) made of hydrophobic fibers. As the elastic element of the side wall elastic member 32, for example, a polyurethane thread, a band-like polyurethane film, or a thread-like or band-like natural rubber is used. In this embodiment, a polyurethane thread is used as the elastic element.

FIG. 3 is a plan view showing the body portion 2 of the absorbent article 1, omitting illustration of the side sheets 3. As shown in FIG. FIG. 4 is an enlarged cross-sectional view showing the absorbent core 4 in FIG. The absorbent core 4 includes an upper layer absorbent body 41 and a lower layer absorbent body 46 . The upper absorbent core 41 is arranged above (on the wearer's side) the lower absorbent core 46 . That is, the lower absorbent core 46 is arranged below (outside) the upper absorbent core 41 . In FIG. 3, the outer shape of the upper absorbent body 41 is indicated by a dashed line. For example, the size of the lower layer absorbent body 46 in the width direction is larger than that of the upper layer absorbent body 41 , and the size of the lower layer absorbent body 46 in the longitudinal direction is substantially the same as that of the upper layer absorbent body 41 .

The lower absorbent core 46 is placed between the upper absorbent core 41 and the backsheet 23 and joined to one or both. In the example of FIG. 4 , the lower absorbent core 46 includes a sheet-like upper fiber assembly 47 and a sheet-like lower fiber assembly 48 . The upper fiber assembly 47 is arranged above (on the wearer's side) the lower fiber assembly 48 , and the lower fiber assembly 48 is arranged between the upper fiber assembly 47 and the backsheet 23 . In this embodiment, the outer shape of the upper fiber assembly 47 is a so-called hourglass shape, and the outer shape of the lower fiber assembly 48 is substantially rectangular. Substantially the entirety of the lower fiber assembly 48, excluding a portion that overlaps with an opening 471, which will be described later, overlaps (is covered with) the upper fiber assembly 47 in the thickness direction (vertical direction in FIG. 4). .

The upper fiber assembly 47 has openings 471 as shown in FIGS. The opening 471 extends longitudinally at substantially the center in the width direction. The length of the opening 471 in the longitudinal direction is smaller than the length of the upper absorbent core 41 . The existing range of the opening 471 in the longitudinal direction overlaps with the urination range R1, which will be described later. The width of the opening 471 in the width direction is greater than the width of the material non-existing region 43, which will be described later. The opening 471 is a slit passing through the upper fiber assembly 47 . The lower fiber assembly 48 does not have openings. Therefore, the lower side of the opening 471 of the upper fiber assembly 47 is closed by the lower fiber assembly 48 . The opening 471 in the lower layer absorbent body 46 is a concave portion recessed toward the back sheet 23 on the surface that contacts the upper layer absorbent body 41 .

Each of the upper fiber assembly 47 and the lower fiber assembly 48 is formed of, for example, regenerated hydrophilic fibers such as cellulose, rayon, cotton, synthetic fibers, pulp fibers, and the like. Upper fiber assembly 47 and lower fiber assembly 48 may comprise a superabsorbent material. Typically, the upper fiber assembly 47 and the lower fiber assembly 48 are wrapped with tissue paper, liquid-permeable nonwoven fabric, or the like. The structure of the lower absorbent body 46 is not limited to the above. For example, the lower absorbent body 46 may have only one fiber assembly, and the fiber assembly may be provided with recesses extending in the longitudinal direction.

As shown in FIG. 4 , the upper absorbent body 41 includes a liquid-permeable upper absorbent sheet 411 , a liquid-permeable lower absorbent sheet 412 , and a superabsorbent material 413 . The upper absorbent sheet 411 is arranged on the top sheet 21 side, and the lower absorbent sheet 412 is arranged on the back sheet 23 side with respect to the upper absorbent sheet 411 . The upper absorbent body 41 has a substantially rectangular shape elongated in the longitudinal direction, and the upper absorbent body sheet 411 and the lower absorbent body sheet 412 both have a shape extending in the longitudinal direction. The outer shape of the upper absorbent sheet 411 and the lower absorbent sheet 412 are substantially the same. In the upper absorbent body 41, a plurality of material-existing regions 42 in which the superabsorbent material 413 is fixed and a plurality of material-absent regions 43 in which the superabsorbent material 413 is not present are provided. In FIG. 3, the material existing region 42 is hatched. 3 and 4 (and FIGS. 5 and 6 to be described later), one material non-existing region is denoted by reference numeral 43a, but unless otherwise specified, the material non-existing region 43a It is the same as non-existing area 43 .

The plurality of material existing regions 42 each have a strip shape extending substantially parallel to the longitudinal direction, and are arranged with gaps in the width direction (that is, apart from each other). In other words, a plurality of material existing regions 42 arranged in stripes extending in the longitudinal direction are provided. In each material presence area 42, a superabsorbent material 413 is disposed between an upper absorbent sheet 411 and a lower absorbent sheet 412 and secured to one or both by hot melt adhesive or the like. In other words, the superabsorbent material 413 is secured to the material presence area 42 . In the examples of FIGS. 3 and 4, the widths of the multiple material presence regions 42 are approximately equal to each other, but they may be different.

The plurality of material non-existing regions 43 are regions of the upper absorber 41 excluding the plurality of material existing regions 42 . Each of the plurality of material non-existence regions 43 has a strip shape extending along the longitudinal direction. In the examples of FIGS. 3 and 4, the widths of the multiple non-material regions 43 are equal to each other, but they may be different. For example, the width of each material non-existing region 43 is smaller than the width of the material existing region 42 . The material non-existing regions 43 and the material existing regions 42 are alternately arranged in the width direction. That is, a material non-existing region 43 is provided between two material existing regions 42 adjacent in the width direction. In FIG. 3 , the boundary line between the material non-existing region 43 and the material existing region 42 is indicated by a dashed line that is thinner than the dashed line that indicates the outer shape of the upper absorbent body 41 .

Typically, no superabsorbent material 413 is present between the upper absorbent sheet 411 and the lower absorbent sheet 412 in each material-free region 43 . Superabsorbent material 413 may be substantially absent, and small amounts of superabsorbent material 413 may be present. In the material absent region 43, a joint portion 44 is provided in which the upper absorbent sheet 411 and the lower absorbent sheet 412 are joined together. The joint portion 44 is a portion of the material absent region 43 of the upper absorbent sheet 411 and the lower absorbent sheet 412 that are joined together. In one example, the joint 44 is formed by adhesive bonding using a hot-melt adhesive or the like. Adhesive bonding is performed by, for example, slot coat coating, curtain coating, or the like, and the adhesive is applied to the entire non-material region 43 between the upper absorbent sheet 411 and the lower absorbent sheet 412 . Preferably, in addition to adhesive bonding, heat sealing (thermal fusion bonding) is performed. In this case, the joints 44 are formed by multiple joints of the upper absorbent sheet 411 and the lower absorbent sheet 412 . Joint 44 does not necessarily have to be a composite joint.

At the joining portion 44 , the upper absorbent sheet 411 and the lower absorbent sheet 412 are joined over the entire non-material region 43 . Upper absorbent sheet 411 and lower absorbent sheet 412 may be non-bonded in a very small portion of material absent region 43 . In the material non-existing region 43, the ratio of the adhesion area of the adhesive between the upper absorbent sheet 411 and the lower absorbent sheet 412 to the area of the material non-existing region 43, that is, the upper side of the material non-existing region 43 The area ratio of the joint region between the absorbent sheet 411 and the lower absorbent sheet 412 is, for example, 80% or more, preferably 85% or more, and more preferably 90% or more. As described above, the material-free region 43 is a region that slightly contains the superabsorbent material 413, that is, a region where the density of the superabsorbent material 413 is sufficiently lower than that of the material-present region 42 (i.e., the material low-density region).

Upper absorbent sheet 411 is joined to top sheet 21 . The joining of the upper absorbent sheet 411 and the top sheet 21 is performed, for example, by spiral coating shown in FIG. In spiral coating, a spiral pattern in which an adhesive 451 such as a hot-melt adhesive is spirally applied along the longitudinal direction is arranged in the width direction. Therefore, as shown in FIG. 4, the upper absorbent sheet 411 and the top sheet 21 are partially joined with an adhesive 451. As shown in FIG.

Here, attention is paid to the central non-material region 43a in the width direction (hereinafter, simply referred to as "the central non-material region 43a"). The central non-material region 43 a is the non-material region closest to the widthwise center of the main body 2 . When two material non-existing regions are positioned near both sides of the center in the width direction, the two material non-existing regions may be identified as the central material non-existing region 43a. As shown in FIG. 5, the central material-free region 43a does not overlap any of the patterns of adhesive 451 in the thickness direction. Therefore, in the central non-material region 43a, the top sheet 21 and the upper absorbent sheet 411 are not joined over the entire longitudinal direction.

Each of the material non-existing regions 43 excluding the central material non-existing region 43a (hereinafter referred to as "material non-existing region 43 other than the center") overlaps one of the patterns of the adhesive 451 over the entire longitudinal direction. . That is, the top sheet 21 and the upper absorbent sheet 411 are joined over the entire longitudinal direction in each non-material region 43 other than the center. Actually, the adhesive 451 exists only partially in the width direction in the non-material area 43 other than the center, and the top sheet 21 and the upper absorbent sheet 411 are partially joined. On the other hand, each material existing region 42 overlaps one of the patterns of the adhesive 451 over the entire longitudinal direction, and the top sheet 21 and the upper absorbent sheet 411 are bonded over the entire longitudinal direction. Also in the material existing region 42, the adhesive 451 exists only partially in the width direction, and the top sheet 21 and the upper absorbent sheet 411 are partially joined. In the non-material region 43 and the material-existing region 42 other than the center, the adhesive 451 may exist discretely in the longitudinal direction or the width direction.

As shown in FIG. 4, the central non-material region 43a overlaps the opening 471 of the upper fiber assembly 47 in the thickness direction. In the two material existing regions 42 adjacent to the central material non-existing region 43a on both sides in the width direction, the portion on the central material non-existing region 43a side overlaps with the opening 471, so that the material non-existing region 43a and the central material non-existing region 43a overlap. , does not overlap with the opening 471 . As described above, the length of the openings 471 in the longitudinal direction is smaller than the length of the upper absorbent core 41 , and both longitudinal ends of the central non-existing region 43 a do not overlap the openings 471 .

The upper absorbent sheet 411 and the lower absorbent sheet 412 of the upper absorbent body 41 are made of, for example, a liquid-permeable nonwoven fabric, like the top sheet 21 . The nonwoven fabric is formed of, for example, hydrophobic fibers (polypropylene, polyethylene, polyester, polyamide, nylon, etc.) whose surface is hydrophilically treated with a surfactant. The nonwoven fabric may be made of hydrophilic fibers such as cellulose, rayon or cotton. The nonwoven fabric is, for example, an air-through nonwoven fabric, a point-bonded nonwoven fabric, a spunbonded nonwoven fabric, a spunlaced nonwoven fabric, or the like. As the super absorbent material 413, for example, a granular super absorbent polymer (SAP (Super Absorbent Polymer)) or a fibrous super absorbent fiber (SAF (Super Absorbent Fiber)) is used.

Here, the nonwoven fabric forming the top sheet 21 and the nonwoven fabric forming the upper absorbent sheet 411 are compared. In the absorbent article 1 , the fineness of the nonwoven fabric of the top sheet 21 is greater than the fineness of the nonwoven fabric of the upper absorbent sheet 411 . In one example, the fineness of the nonwoven fabric of the top sheet 21 is 4.4 dtex or more. The fineness of the nonwoven fabric of the top sheet 21 is, for example, 1.1 times or more, preferably 1.5 times or more, that of the nonwoven fabric of the upper absorbent sheet 411 . Although the upper limit is not particularly limited, it is, for example, 3.5 times, preferably 3.0 times. Moreover, the basis weight of the nonwoven fabric of the top sheet 21 is larger than the basis weight of the nonwoven fabric of the upper absorbent sheet 411 . In one example, the nonwoven fabric of the top sheet 21 has a basis weight of 25 g/m ² or more. The basis weight of the nonwoven fabric of the top sheet 21 is, for example, 1.1 times or more, preferably 1.2 times or more, that of the nonwoven fabric of the upper absorbent sheet 411 . Although the upper limit is not particularly limited, it is, for example, 2.5 times, preferably 2.0 times.

Furthermore, the compressibility of the nonwoven fabric of the top sheet 21 under a predetermined load is smaller than the compressibility of the nonwoven fabric of the upper absorbent sheet 411 . For measuring the compressibility, for example, a compression tester (KES-G5) manufactured by Kato Tech Co., Ltd. is used. Samples of 50×50 mm were prepared for each of the nonwoven fabric of the top sheet 21 and the nonwoven fabric of the upper absorbent sheet 411, and were pressed to a maximum load of 50 gf/cm ² with a pressurized area of 2 cm ² using a compression tester. The rate of change in sample thickness at time (ie, (absolute value of thickness change due to pressure/thickness before pressure)) is measured as the compressibility. The measurement conditions in the compression tester are SENS: 2 and compression speed: 0.02 mm/sec.

In one example of the absorbent article 1 , the fiber orientation of the nonwoven fabric of the top sheet 21 (typically, the longitudinal direction of the nonwoven fabric pulled out from a roll) is substantially parallel to the longitudinal direction of the main body 2 , and the upper absorbent sheet 411 The fiber orientation of the nonwoven fabric is also substantially parallel to the longitudinal direction of the main body portion 2 . Therefore, both the nonwoven fabric of the top sheet 21 and the nonwoven fabric of the upper absorbent sheet 411 are difficult to stretch in a direction corresponding to the longitudinal direction of the main body 2 (hereinafter simply referred to as "longitudinal direction").

Further, in a tensile test described later, a load (hereinafter simply referred to as "3 % elongation load”) is greater than the 3% elongation load in the width direction of the nonwoven fabric of the upper absorbent sheet 411 . The 3% elongation load of the top sheet 21 in the width direction is, for example, 2.0 times or more, preferably 2.2 times or more, the 3% elongation load of the upper absorbent sheet 411 . Although the upper limit is not particularly limited, it is, for example, 10.0 times. As described above, the top sheet 21 is more difficult to stretch in the width direction than the upper absorbent sheet 411 . In other words, the upper absorbent sheet 411 stretches more easily in the width direction than the top sheet 21 does. Actually, the lower absorbent sheet 412 also tends to stretch in the width direction more than the top sheet 21 does.

In the absorbent article 1, when excretion such as urine is excreted by the wearer, part of the moisture reaching the absorbent core 4 via the top sheet 21 passes through the material non-existing region 43 and reaches the lower absorbent core. 46 and absorbed by the lower layer absorbent 46 . Typically, excrement is received in the vicinity of the center in the width direction of the main body portion 2, so moisture reaching the absorbent core 4 passes through the central non-material region 43a to reach the opening 471 of the lower absorbent body 46 and It is guided to the vicinity thereof and absorbed by the portion of the upper fiber assembly 47 near the opening 471 and the lower fiber assembly 48 . Another part of the moisture is absorbed by the superabsorbent material 413 in the material existence region 42 of the upper absorbent body 41 . Specifically, as shown in FIG. 6, water is absorbed by the high-absorbent materials 413 of the two material-existing regions 42 adjacent to the central non-material-existing region 43a on both sides in the width direction. The elastic material 413 swells.

At this time, since the upper absorbent sheet 411 and the lower absorbent sheet 412 tend to stretch in the width direction, the upper absorbent sheet 411 and the lower absorbent sheet 412 in the two material existing regions 42 are swollen high. It deforms to match the absorbent material 413 . In addition, in the material non-existence region 43, the joint (joint portion 44) between the upper absorbent sheet 411 and the lower absorbent sheet 412 is approximately maintained.

On the other hand, the top sheet 21 is difficult to stretch in the width direction. Therefore, in the central non-material-existing region 43a, when the swelling rate (water absorption) of the super-absorbent material 413 in the adjacent material-existing regions 42 increases, the top sheet 21 ceases to follow the deformation of the super-absorbent material 413. The top sheet 21 separates from the upper absorbent sheet 411 in the central material-free region 43a. As a result, a space 81 is formed between the top sheet 21 and the upper absorbent sheet 411 in the central non-material region 43a. Actually, the top sheet 21 and the upper absorbent sheet 411 are not separated over the entire non-material region 43a in the longitudinal direction, and the swelling rate of the superabsorbent material 413 in the adjacent material-existing regions 42 is large. In the region, separation between the top sheet 21 and the upper absorbent sheet 411 occurs.

In the absorbent article 1, the space 81 promotes the diffusion of water in the longitudinal direction, making it possible to use a wide area of the absorbent core 4 for water absorption. In addition, even if moisture seeps out of the lower absorbent core 46 due to the body pressure of the wearer, the moisture is retained in the space 81 to prevent the moisture from seeping out to the surface of the top sheet 21 facing the wearer ( That is, liquid return) is suppressed. In addition, since the central non-material region 43a and the material-existing regions 42 on both sides overlap with the openings 471 of the lower absorbent body 46 in the thickness direction, the lower absorbent body 46 has less openings 471 than the openings 471. , the central non-material region 43a of the upper absorbent core 41 is likely to be arranged on the back sheet 23 side. In other words, the material non-existing region 43a in the center becomes more likely to separate from the top sheet 21 toward the opening 471 (more likely to fall into the opening 471), and the space 81 expands in the thickness direction. As described above, since the compressibility of the top sheet 21 under a given load is smaller than that of the upper absorbent sheet 411, the top sheet 21 is less likely to be compressed and has higher rigidity, and the spaces 81 are more likely to be maintained.

By the way, in the absorbent article 1, a predetermined range in the longitudinal direction (hereinafter referred to as "urination range") is likely to receive urination from the wearer. For example, it is assumed that the lower end of the main body 2 of FIG. 3 is arranged on the wearer's ventral side (front side), and the upper end is arranged on the wearer's dorsal side (rear side). In this case, assuming that the ventral edge of the upper absorbent body 41 is 0 and the dorsal edge is 100 in the longitudinal direction, the urination range R1 is 20 to 40 as indicated by the arrow in FIG. range. Therefore, in order to improve liquid diffusibility and suppress liquid return by the above-described space 81, the top sheet 21 and the upper absorbent sheet 411 are arranged over the entire urination range R1 in the central non-existing region 43a. It is preferable that the top sheet 21 and the upper absorbent sheet 411 are joined in the urination range R1 in the material existing regions 42 on both sides of the central material non-existing region 43a. As described above, the portion where the space 81 is formed in the central non-existing region 43a overlaps the opening 471 of the lower absorbent body 46 in the thickness direction, thereby making it easier for the space 81 to expand in the thickness direction. . Therefore, it is preferable that the opening 471 of the lower absorbent body 46 also extends over the entire urination range R1 in the longitudinal direction.

The absorbent article 1 may employ a design that allows each end in the longitudinal direction to be placed on either the ventral side or the dorsal side. In addition, depending on the usage conditions of the absorbent article 1, it is conceivable to use the absorbent article 1 with the designed ventral end portion positioned on the back side of the wearer. Furthermore, excrement such as stool is received at substantially the center in the longitudinal direction. Considering these points, the range in which the top sheet 21 and the upper absorbent sheet 411 are not joined in the central non-material region 43a is preferably in the range of 20 to 80, more preferably in the range of 0 to 100. is more preferable. The same applies to the range where the top sheet 21 and the upper absorbent sheet 411 are joined in the material existing regions 42 on both sides of the central material non-existing region 43a.

In addition, in the absorbent core 4 of FIG. 6 , the top sheet 21 and the upper absorbent sheet 411 are only partially joined in the material non-existing region 43 other than the center, so that the adjacent material existing region 42 Due to the swelling of the superabsorbent material 413, the top sheet 21 may be peeled off from the upper absorbent sheet 411 in the material absent region 43 to form a space. Such separation between the top sheet 21 and the upper absorbent sheet 411 may occur in the material existing areas 42 on both sides of the central material absent area 43a. A larger space 81 is formed between. Of course, the top sheet 21 and the upper absorbent sheet 411 are also non-joined over the entire urination range R1 (the entire range of 0 to 100 may be acceptable) in the non-material region 43 other than the center. , a space 81 may be formed.

Next, experimental examples relating to the absorbent article 1 will be described. Here, the tensile properties of the top sheet 21 and the upper absorbent sheet 411 were measured. In measuring the tensile properties, a nonwoven fabric forming the top sheet 21 of the absorbent article 1 and a nonwoven fabric forming the upper absorbent sheet 411 were prepared. The fineness of the nonwoven fabric of the top sheet 21 is 4.4 dtex, and the fineness of the nonwoven fabric of the upper absorbent sheet 411 is 2.0 dtex. The nonwoven fabric of the top sheet 21 has a basis weight of 25 g/m ² , and the upper absorbent sheet 411 has a basis weight of 17 g/m ² . The fineness and basis weight of each of the top sheet 21 and the upper absorbent sheet 411 in the absorbent article 1 are not limited to the above. Then, each nonwoven fabric was subjected to a tensile test in accordance with JIS L1913 6.3.1 in both the longitudinal direction and the width direction, and the 3% elongation load, tensile strength and tensile elongation were measured as tensile properties. Table 1 shows the measurement results of tensile properties.

As already mentioned, the longitudinal direction is generally parallel to the fiber orientation of the nonwoven fabric (typically the longitudinal direction of a nonwoven fabric drawn from a roll), and the width direction is generally perpendicular to the fiber orientation of the nonwoven fabric. The 3% elongation load is the load when the sample length before the test is elongated by 3% in each direction. A nonwoven fabric with a higher 3% elongation load in each direction requires a greater force to elongate 3% of the reference length, and is difficult to elongate in that direction. The tensile strength is the value obtained by dividing the load when the sample is stretched until it breaks in the tensile test by the width (50 mm) of the sample. Tensile elongation is the elongation rate of a sample until the sample breaks in a tensile test.

When focusing only on the width direction, the nonwoven fabric of the top sheet 21 was larger than the nonwoven fabric of the upper absorbent sheet 411 in all of the 3% elongation load, tensile strength and tensile elongation. Specifically, the 3% elongation load in the width direction of the nonwoven fabric of the top sheet 21 is 2.0 times or more that of the nonwoven fabric of the upper absorbent sheet 411 . Thus, it was confirmed that the top sheet 21 is significantly less stretchable than the upper absorbent sheet 411 in the width direction. The tensile strength in the width direction of the nonwoven fabric of the top sheet 21 is also sufficiently higher than that of the nonwoven fabric of the upper absorbent sheet 411 (actually, it is 2.0 times or more).

As described above, in the absorbent article 1 , the absorbent core 4 includes the upper absorbent body 41 in which the super absorbent material 413 is fixed between the upper absorbent sheet 411 and the lower absorbent sheet 412 . In the upper absorbent body 41 , a plurality of material existing regions 42 to which the superabsorbent material 413 is fixed are arranged with a gap in the width direction. A material-free region 43 is provided in which the organic material 413 is absent. Also, the upper absorbent sheet 411 and the lower absorbent sheet 412 are wholly joined in each material absent region 43 . When focusing on the urination range R1 in which the wearer urinates in the longitudinal direction, the top sheet 21 and the upper absorbent sheet 411 extend over the entire urination range R1 in the material non-existence region 43a at the center in the width direction. The top sheet 21 and the upper absorbent sheet 411 are joined in each of the two material existing regions 42 which are non-bonded and which are adjacent to the central material non-existing region 43a on both sides in the width direction. The load when the nonwoven fabric forming the top sheet 21 is stretched by 3% in the width direction is greater than the load when the nonwoven fabric forming the upper absorbent sheet 411 is stretched by 3% in the width direction.

In the absorbent article 1, the swelling of the superabsorbent material 413 separates the top sheet 21 from the upper absorbent sheet 411 in the central non-existing region 43a, and a space 81 is formed between the top sheet 21 and the upper absorbent sheet 411. can be formed. As a result, the space 81 can improve liquid diffusibility and suppress liquid return. In addition, it is possible to prevent the top sheet 21 from greatly recessing toward the absorbent core 4 in the central non-material region 43a, thereby suppressing deterioration of the wearing feeling.

Preferably, the load when the nonwoven fabric forming the top sheet 21 is stretched by 3% in the width direction is at least 2.0 times the load when the nonwoven fabric forming the upper absorbent sheet 411 is stretched by 3% in the width direction. be. Thereby, the space 81 can be formed more reliably in the central non-material region 43a.

Preferably, the fineness of the nonwoven fabric forming the top sheet 21 is 1.1 times or more the fineness of the nonwoven fabric forming the upper absorbent sheet 411, or/and the basis weight of the nonwoven fabric forming the top sheet 21 is It is 1.1 times or more the basis weight of the nonwoven fabric forming the absorbent sheet 411 . Since the fineness and/or basis weight of the top sheet 21 is large in this way, the rigidity of the top sheet 21 is made higher than that of the upper absorbent sheet 411, and the space 81 is more reliably formed in the central non-existing region 43a. be able to.

Preferably, the compressibility of the nonwoven fabric forming the top sheet 21 under a given load is smaller than the compressibility of the nonwoven fabric forming the upper absorbent sheet 411 . Thus, since the top sheet 21 is hard to be compressed and has high rigidity, the space 81 can be held more reliably.

Preferably, the absorbent core 4 further comprises a lower absorbent core 46 arranged between the upper absorbent core 41 and the backsheet 23 and having a sheet-like fiber assembly. Thereby, the absorption amount in the absorbent core 4 can be increased.

Preferably, the lower absorbent body 46 has a recess (opening 471 in the above example) recessed toward the backsheet 23 on the surface that contacts the upper absorbent body 41, and the recess is at least longitudinally urinated. While expanding to the range R1, it overlaps with the central material non-existing region 43a and the two material existing regions 42 on both sides of the central material non-existing region 43a. As a result, the space 81 can be enlarged in the thickness direction, the liquid diffusion property can be further improved, and the liquid return can be further suppressed.

Various modifications of the absorbent article 1 are possible.

If the space 81 can be formed in the central non-material region 43 a , the 3% elongation load in the width direction of the nonwoven fabric of the top sheet 21 is 2.2% of the 3% elongation load of the nonwoven fabric of the upper absorbent sheet 411 . It may be less than 0 times. Similarly, the fineness of the nonwoven fabric of the top sheet 21 may be less than 1.1 times the fineness of the nonwoven fabric of the upper absorbent sheet 411 , and the basis weight of the nonwoven fabric of the top sheet 21 may be less than that of the nonwoven fabric of the upper absorbent sheet 411 . It may be less than 1.1 times the basis weight. Further, the compressibility of the nonwoven fabric of the top sheet 21 under a predetermined load may be equal to or higher than the compressibility of the nonwoven fabric of the upper absorbent sheet 411 .

Depending on the design of the absorbent article 1, the concave portion of the lower absorbent body 46 may be omitted. Further, in the absorbent core 4, the lower absorbent body 46 may be omitted.

The bonding between the upper absorbent sheet 411 and the lower absorbent sheet 412 and the bonding between the top sheet 21 and the upper absorbent sheet 411 may be other than adhesive bonding.

The number and shape of the material existing regions 42 provided in the absorbent core 4 may be varied. The material non-existing region 43 may have a shape other than a linear shape, and may, for example, extend continuously in a mesh shape along the longitudinal direction.

The side sheet 3 may be omitted from the absorbent article 1. The structure of the absorbent article 1 may be used for absorbent articles other than auxiliary absorbent pads, such as pants-type and tape-type disposable diapers.

The configurations in the above embodiment and each modified example may be combined as appropriate as long as they do not contradict each other.

1 Absorbent Article 2 Body Part 4 Absorbent Core 21 Top Sheet 23 Back Sheet 41 Upper Layer Absorber 42 Material Presence Regions 43, 43a Material Absence Region 46 Lower Layer Absorber 411 Upper Absorbent Sheet 412 Lower Absorbent Sheet 413 Highly Absorbent Material 471 Opening R1 Urination Area

Claims (7)

An absorbent article that receives excrement from a wearer,
a liquid-permeable topsheet;
a water-repellent or liquid-impermeable backsheet;
a longitudinally extending absorbent core disposed between the topsheet and the backsheet;
with
wherein the absorbent core comprises an absorbent body in which a superabsorbent material is secured between an upper absorbent sheet and a lower absorbent sheet;
In the absorbent body, a plurality of material existing regions to which the superabsorbent material is fixed are arranged with a gap in the width direction, and between two material existing regions adjacent to each other in the width direction, the superabsorbent material absent regions are provided where no material is present, and in each material absent region, the upper absorbent sheet and the lower absorbent sheet are entirely joined together;
When focusing on the predetermined range in the longitudinal direction that receives urination from the wearer, the top sheet and the upper absorbent sheet extend over the entire predetermined range in the material non-existence region in the center in the width direction. The top sheet and the upper absorbent sheet are joined in each of two non-bonded material existing regions adjacent to both sides in the width direction with respect to the central non-material existing region,
The load when the nonwoven fabric forming the top sheet is stretched by 3% in the width direction is larger than the load when the nonwoven fabric forming the upper absorbent sheet is stretched by 3% in the width direction. absorbent article. The absorbent article according to claim 1,
The load when the nonwoven fabric forming the top sheet is stretched 3% in the width direction is 2.0 times or more the load when the nonwoven fabric forming the upper absorbent sheet is stretched 3% in the width direction. An absorbent article characterized by: The absorbent article according to claim 1 or 2,
The absorbent article, wherein the fineness of the nonwoven fabric forming the top sheet is 1.1 times or more the fineness of the nonwoven fabric forming the upper absorbent sheet. The absorbent article according to any one of claims 1 to 3,
The absorbent article, wherein the basis weight of the nonwoven fabric forming the top sheet is 1.1 times or more the basis weight of the nonwoven fabric forming the upper absorbent sheet. The absorbent article according to any one of claims 1 to 4,
An absorbent article, wherein the compressibility of the nonwoven fabric forming the top sheet under a predetermined load is smaller than the compressibility of the nonwoven fabric forming the upper absorbent body sheet. The absorbent article according to any one of claims 1 to 5,
An absorbent article, wherein the absorbent core further comprises another absorbent body arranged between the absorbent body and the backsheet and having a sheet-like fiber assembly. The absorbent article according to claim 6,
The other absorbent body has a recess recessed toward the back sheet on the surface in contact with the absorbent body,
The recess extends at least over the predetermined range in the longitudinal direction and overlaps the central non-material region and the two material non-existing regions on both sides of the central non-material region. sexual goods.

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