JP7478038B2 - Absorbent articles - Google Patents

Description

The present invention relates to an absorbent article.

Absorbent articles generally comprise a liquid-permeable top sheet, a liquid-impermeable back sheet, and an absorbent body disposed between them, and the absorbent body absorbs and retains bodily fluids such as urine that permeate the top sheet. There are various types of absorbent articles for both adults and infants, depending on the intended use, such as tape-type disposable diapers, pants-type disposable diapers, urine pads, and light incontinence pads.

Conventionally, fluff pulp and super absorbent polymer (hereinafter referred to as "SAP") have been used together as an absorbent. However, in order to further improve the wearing comfort, appearance, and feel of absorbent articles, and to further reduce the backflow of body fluids such as urine, various absorbent articles have been proposed that use a super absorbent sheet (hereinafter referred to as "SAP sheet") containing two sheets of nonwoven fabric and SAP particles fixed between them with a hot melt adhesive.

Patent Document 1 discloses an SAP sheet comprising first and second nonwoven fabrics, each having one surface coated with an adhesive, and a plurality of SAP layers arranged in stripes extending in the longitudinal direction between the adhesive-coated surfaces of the first and second nonwoven fabrics, in which adhesive is intermittently applied to the area of the adhesive-coated surface of the second nonwoven fabric facing the SAP layer, and adhesive is continuously applied in the longitudinal direction to the adhesive-coated surfaces of the first and second nonwoven fabrics that directly face the SAP layer on both sides of the width of the SAP layer without an intervening SAP layer.

Patent Document 2 discloses an SAP sheet in which the absorbent disposed between the top sheet and the back sheet comprises first and second absorbents each including two sheets of nonwoven fabric with SAP particles disposed therebetween, and the first and second absorbents disposed on one side and the other in the width direction have first and second folds extending in the longitudinal direction, respectively, and the first and second folds face each other. Furthermore, Patent Document 2 discloses an absorbent article further comprising a third absorbent including two sheets of nonwoven fabric with SAP particles disposed therebetween, the third absorbent being disposed above the first and second absorbent bodies.

JP 2006-158676 A JP 2013-42882 A (Claim 1, Claim 5)

The SAP sheets used in Patent Documents 1 and 2 and many other absorbent articles have poor compressibility in the thickness direction, so that the wearer is likely to feel the rough and hard feel of the SAP particles and the hardened body of the hot melt adhesive on the skin, significantly reducing the wearing comfort and fit, and causing a great sense of discomfort when wearing. Furthermore, in many SAP sheets, the SAP particles are fixed to the nonwoven fabric with a hot melt adhesive, so that the SAP particles are present at a high density on the surface, resulting in less space for the SAP particles to absorb body fluids and expand. For this reason, conventional SAP sheets are not fully satisfactory in terms of the diffusion and absorption speed of body fluids (especially the absorption speed after repeated absorption), and ultimately in terms of absorbency.

In addition, conventional SAP sheets are made from SAP and nonwoven fabric to reduce thickness, and do not contain fluff pulp, which causes the problem of poor wetback immediately after absorbing water. In addition, when a paper sheet is used instead of nonwoven fabric, the tensile strength is low when wet, so there is a problem that the SAP sheet may break due to body pressure after absorbing water, which may cause the SAP to leak outside the absorbent article.

The object of the present invention is to provide an absorbent article that is equipped with a highly absorbent sheet, has a good wearing feeling and fit, and has excellent diffusion and absorption speed of bodily fluids.

As a result of intensive research conducted by the inventors to solve the above problems, it was discovered that a highly absorbent sheet can be constructed by combining, in a specific structure, a base nonwoven fabric having a raised surface and carrying a highly absorbent polymer between the raised fibers of the raised surface with a pulp-containing nonwoven fabric as a hydrophilic sheet having a specific bending stiffness and wet strength, and by using this highly absorbent sheet as an absorbent body, an absorbent article that meets the objectives can be obtained, which led to the completion of the present invention. The present invention relates to the following absorbent article.

(1) An absorbent article comprising a liquid-permeable top sheet, a liquid-impermeable back sheet, and an absorbent body disposed between the top sheet and the back sheet,
The absorbent body is
a base nonwoven fabric having a raised surface and a non-raised surface, the non-raised surface being disposed so as to face the top sheet;
a highly absorbent polymer fixedly supported between the raised fibers on the raised surface of the base nonwoven fabric;
a hydrophilic sheet covering the raised surface of the base nonwoven fabric;
the hydrophilic sheet includes a pulp-containing nonwoven fabric having a bending stiffness of 0.02 gf·cm ² /cm or more and a wet strength of 10 N/50 mm or more;
the absorbent body has a three-dimensional shape inwardly folded in three so that the non-raised surface of the highly absorbent sheet is on the inside and both widthwise end surfaces of the base nonwoven fabric face each other on the non-skin side of the top sheet,
An absorbent article, wherein the distance between both end faces in the width direction of the base nonwoven fabric is 10% or more and 90% or less of the width direction dimension of the absorbent body.
(2) The absorbent article of (1) above, wherein the absorbent body has a groove portion with a slit space between both widthwise end faces of the base nonwoven fabric and the non-raised surface as a bottom surface, the hydrophilic sheet is stretched in the width direction so that both widthwise end faces cover and overlap the slit space of the groove portion, and the widthwise dimension of the overlap is 5% to 50% of the widthwise dimension of the absorbent body.
(3) The absorbent article according to (1) or (2) above, wherein the pulp-containing nonwoven fabric has a basis weight of 30 g/ ^m2 or more and 80 g/ ^m2 or less.
(4) The absorbent article according to any one of (1) to (3) above, wherein the base nonwoven fabric is an air-through nonwoven fabric, the basis weight of the air-through nonwoven fabric is 20 g/ ^m2 or more and 80 g/ ^m2 or less, and the thickness of the fibers constituting the air-through nonwoven fabric is 1.6 dtex or more and 14 dtex or less.
(5) The absorbent article according to any one of (1) to (4) above, wherein the basis weight of the superabsorbent polymer in the superabsorbent sheet is 150 g/ ^m2 or more and 800 g/ ^m2 or less.

The present invention provides an absorbent article that is equipped with a highly absorbent sheet, has a good wearing feel and fit, and has excellent diffusion and absorption speed of bodily fluids.

1 is a plan view illustrating a schematic configuration of an absorbent article according to a first embodiment of the present invention. FIG. 2 is a perspective view showing a schematic configuration of a base nonwoven fabric in the absorbent article shown in FIG. 1 . FIG. 2 is a side view showing a schematic configuration in which a highly absorbent polymer is fixedly supported on a base nonwoven fabric in the absorbent article shown in FIG. 1. FIG. 2 is a schematic cross-sectional view showing the configuration of an absorbent body in the absorbent article shown in FIG. 1 . FIG. 4 is a schematic cross-sectional view showing the configuration of a second embodiment of the absorbent body.

In this specification, wearing an absorbent article refers to the state in which the absorbent article is attached to the body, regardless of whether bodily fluids have been absorbed or not. In an absorbent article, the longitudinal direction is the direction indicated by Y in the figure that extends from the front to the back of the body via the wearer's crotch when the absorbent article is worn on the body, the width direction is the direction indicated by X in the figure that is perpendicular to the longitudinal direction, and the thickness direction is the direction indicated by Z in the figure in which the components are stacked. The skin side is the surface that contacts the wearer's skin or faces the skin when the absorbent article is worn, and the non-skin side is the surface that contacts the wearer's clothing or faces the clothing. Body fluids refer to liquids discharged from the body to the outside, such as urine, blood, and water in loose stools.

<Absorbent article (first embodiment)>
The absorbent article of the present embodiment will be described below with reference to the drawings. Fig. 1 shows an absorbent article 50 according to the first embodiment. Fig. 2 shows a base nonwoven fabric 11. Fig. 3 shows a base nonwoven fabric 11 having a highly absorbent polymer 12 fixed thereto. Figs. 4 and 5 show absorbents 1 and 2, respectively. These drawings do not stipulate the shape, dimensions, size relationship, etc. of each component member in the absorbent article 50.

The absorbent article 50 of this embodiment can be used as various absorbent articles for both babies and adults, and representative examples include light incontinence pads, urine absorption pads, pants-type paper diapers, tape-fastened paper diapers, etc. Various paper diapers as outerwear may be combined with the absorbent article 50 as innerwear. The longitudinal and width dimensions of the absorbent article 50 are not particularly limited, but are, for example, in the range of 100 mm to 800 mm and 50 mm to 500 mm. By adjusting the dimensions of the absorbent article 50 to fall within the above ranges, absorbent articles for various uses can be easily obtained.

As shown in FIG. 1, the absorbent article 50 comprises a liquid-permeable top sheet 25 that is positioned relatively close to the skin when the absorbent article 50 is worn, a liquid-impermeable back sheet 30 that is positioned opposite the top sheet 25 and is positioned relatively close to the skin when the absorbent article 50 is worn, an absorbent body 1 that is positioned between the top sheet 25 and the back sheet 30, and a pair of three-dimensional gathers 40 that are provided on the skin-side surface of the top sheet 25. The absorbent body 1 is sandwiched between the top sheet 25 and the back sheet 30, and body fluids such as urine are absorbed and retained in the absorbent body 1 through the top sheet 25. Leg gathers, waist gathers, side flaps, etc. can be provided as appropriate depending on the purpose and type of the absorbent article 50.

The absorbent article 50 has a highly absorbent sheet 10 as an absorbent body 1 that does not contain fluff pulp, has good absorption performance, and is unlikely to experience a decrease in absorption rate due to gel blocking of the highly absorbent polymer 12 even when repeatedly absorbing body fluids. This allows the absorbent article 50 to maintain a smooth and comfortable feel on the skin, have a good wearing feel and fit, and does not feel strange when worn. It also quickly absorbs body fluids, has excellent body fluid diffusion properties, and has a high absorption rate. Furthermore, the absorbent article 50 has an absorbent body 1 that combines a highly absorbent sheet 10 including a base nonwoven fabric 11 having a raised surface 11a and a highly absorbent polymer fixedly supported on the raised surface 11a, and a pulp-containing nonwoven fabric having predetermined characteristics as a hydrophilic sheet 20 in a predetermined inward three-fold structure, and thus has the advantage of significantly suppressing liquid return not only when the body fluid is retained, but also when the wearer has excreted the body fluid and the body fluid is not sufficiently retained.

The sheet-like or plate-like components are described in more detail below in the order of the top sheet 25, absorbent body 1, back sheet 30, and three-dimensional gathers 40. Note that these components may have a three-dimensional structure other than a sheet or plate shape.

(Top sheet)
The top sheet 25 is a liquid-permeable sheet-like member that quickly passes bodily fluids toward the absorbent body 1, and is disposed opposite the back sheet 30 with the absorbent body 1 sandwiched therebetween. Since the top sheet 25 may come into contact with the wearer's skin, a substrate that is soft to the touch and does not irritate the skin is preferable. Examples of the substrate include hydrophilic sheets, composite nonwoven fabrics that are laminates of the same or different hydrophilic sheets, open-ended films such as open-ended polyethylene films, and foamed films such as polyethylene foam and urethane foam. The hydrophilic sheet can be obtained by processing synthetic fibers made of synthetic resins such as polypropylene and polyethylene, regenerated fibers such as rayon, and natural fibers such as cotton, using known methods such as the air-through method, the thermal bond method, the spunlace method, and the spunbond method.

The surface of the top sheet 25 may be embossed or perforated in accordance with a known method in order to improve liquid permeability. In addition, in order to reduce irritation to the skin, the top sheet 25 may contain one or more of lotions, antioxidants, anti-inflammatory ingredients, pH adjusters, antibacterial agents, moisturizers, etc.

From the viewpoints of strength, processability, and liquid return, the basis weight of the top sheet 25 is, for example, in the range of 15 g/m ² to 40 g/m ^2. The shape of the top sheet 25 is not particularly limited, and may be any shape that covers all or a part of the absorbent body 1, which is necessary for guiding bodily fluids to the absorbent body 1 without leakage.

<First embodiment of absorbent body>
4 is a schematic cross-sectional view showing the absorbent body 1. The absorbent body 1 has a three-dimensional structure in which a highly absorbent sheet (hereinafter also referred to as "SAP sheet") 10 including a base nonwoven fabric 11 having a highly absorbent polymer 12 fixedly supported on its raised surface 11a and a hydrophilic sheet 20 is folded in three. The base nonwoven fabric 11 has a raised surface 11a on one surface and a non-raised surface 11b on the other surface, and the highly absorbent polymer 12 is fixedly supported between the raised fibers 11x on the raised surface 11a of the base nonwoven fabric 11. In the highly absorbent sheet 10, the highly absorbent polymer 12 is dispersed and fixedly supported between the raised fibers 11x of the base nonwoven fabric 11, so that body fluids such as urine are appropriately diffused around the highly absorbent polymer 12 and quickly retained, improving the absorption performance, and sufficient absorption performance can be ensured even without containing fluff pulp.

In the absorbent body 1 of this embodiment, the highly absorbent sheet 10, in which the entire raised surface 11a of the base nonwoven fabric 11 is covered with the hydrophilic sheet 20, is folded in three (hereinafter also referred to as "C-fold") with the non-raised surface 11b of the base nonwoven fabric 11 facing inwards, and has a three-dimensional shape in which the cross-sectional view in the width direction is a roughly C-shaped shape rotated 90 degrees to the left. In the absorbent body 1, a part of the non-raised surface 11a of the base nonwoven fabric 11 faces the top sheet 25, and one end surface 1A and the other end surface 1B in the width direction of the base nonwoven fabric 11 and one end surface 20a and the other end surface 20b in the width direction of the hydrophilic sheet 20 face each other in the width direction on the non-skin side of the top sheet 25. Here, one end surface 1A and the other end surface 1B in the width direction of the base nonwoven fabric 11 are covered by one end surface 20a and the other end surface 20b in the width direction of the hydrophilic sheet 20, and are configured not to be exposed to the top sheet 25.

In addition, the absorbent body 1 of this embodiment has a groove portion 21 in which one end surface 20a in the width direction of the hydrophilic sheet 20 faces the other end surface 20b, and further, the space where one end surface 1A in the width direction of the base nonwoven fabric 11 faces the other end surface 1B is an opening, and the non-raised surface 11b of the base nonwoven fabric 11 facing the top sheet 25 is the bottom surface. The groove portion 21 functions, for example, like a slit, and forms a diffusion layer in cooperation with the top sheet 25 and the hydrophilic sheet 20, and can distribute body fluids evenly to the vicinity of both ends in the longitudinal direction of the absorbent body 1. As a result, the body fluid diffusion and absorption speed in the absorbent body 1 can be further increased, and the return of body fluids to the top sheet 25 side can be reduced. The length dimension C (also the width dimension of the opening of the groove portion 21 in FIG. 4) between one end face 1A and the other end face 1B in the width direction of the base nonwoven fabric 11 (or between one end face 20a and the other end face 20b in the width direction of the hydrophilic sheet 20) is, for example, in the range of 10% to 90% or 15% to 35% of the width dimension D of the absorbent body 1. This further improves the absorption speed of the absorbent body 1.

In this embodiment, when the superabsorbent polymer 12 is fixed between the raised fibers 11x on the raised surface 11a of the base nonwoven fabric 11, the superabsorbent polymer 12 is supported by the raised surface 11a and the raised fibers 11x, and the superabsorbent polymer 12 is easily dispersed. This reduces the amount of hot melt adhesive used, suppresses the densification of the superabsorbent polymer 12, and forms a space around the superabsorbent polymer 12 in which the superabsorbent polymer 12 can absorb body fluids and expand. In addition, gel blocking, in which the superabsorbent polymers 12 that have absorbed and swelled with body fluids are bonded together, is very unlikely to occur. As a result, the body fluid diffusion and body fluid absorption speed of the absorbent 1 as a whole are increased, and the stiff feeling caused by the hot melt adhesive is less likely to occur. In addition, because the raised surface 11a of the base nonwoven fabric 11, which is a constituent member of the absorbent body 1, is covered with a pulp-containing nonwoven fabric serving as a hydrophilic sheet 20, bodily fluids are distributed evenly throughout the absorbent body 1, and the highly absorbent polymer 12 distributed throughout the absorbent body 1 can be used to absorb bodily fluids efficiently. Therefore, the absorbent article 50 including the absorbent body 1 has high bodily fluid diffusion and absorption speed, excellent bodily fluid absorbency, and is comfortable to wear.

In addition, in this embodiment, the base nonwoven fabric 11 and the hydrophilic sheet 20 are folded in a C-shape, which further improves cushioning and fit, providing a good wearing feel, and the absorbent layer of superabsorbent polymer 12 fixed and supported on the napped surface 11a is divided into two layers, upper and lower, with the upper absorbent layer having grooves 21 that are slits and excellent in bodily fluid diffusion and absorption, and the lower absorbent layer and both ends in the width direction in the C-folded state being fixed and supported layers of superabsorbent polymer 12 with excellent repeated absorption. With this configuration, a high level of fit, wearing comfort, and absorption speed during repeated absorption can be achieved, and wetback immediately after excretion of bodily fluids can be sufficiently prevented.

The absorbent body 1 of this embodiment has a longitudinal dimension in the range of, for example, 100 mm to 800 mm, or 150 mm to 500 mm. The widthwise dimension D of the absorbent body 1 is, for example, 50 mm to 500 mm, or 60 mm to 400 mm. The absorbent body 1 may be embossed on the entire surface or a part thereof.
The base nonwoven fabric 11, the highly absorbent polymer 12, and the hydrophilic sheet 20 constituting the highly absorbent sheet 10 of the absorbent body 1 are as follows.

(Nonwoven Base Fabric)
As shown in Fig. 2, one side surface 11a of the base nonwoven fabric 11 is made of raised fibers 11x which are fibers constituting the base nonwoven fabric 11. Therefore, in addition to the bulkiness inherent to the nonwoven fabric, the high absorbent sheet 10 is given a suitable thickness and softness, which generates a suitable cushioning property and improves the fit when worn. Furthermore, by raising the base nonwoven fabric 11 as described above, the high absorbent polymer 12 can be dispersed and fixedly supported between the raised fibers 11x of the base nonwoven fabric 11. Methods for raising the one side surface 11a of the base nonwoven fabric 11 include methods using a rotary saw blade, needle punch, etc., and the method using a rotary saw blade is preferred from the viewpoint of in-line productivity and cost.

The state of the raised fabric in this embodiment is not particularly limited, and it is sufficient if the raised fabric can be visually confirmed. More specifically, the raised fabric ratio of the base nonwoven fabric 11 is preferably 5% to 90%, and more preferably 8% to 80%. The raised fabric ratio means the increase in the thickness of the base nonwoven fabric 11 due to the raising process. For example, when the thickness of the base nonwoven fabric 11 before raising is T1 and the thickness of the base nonwoven fabric 11 after raising is T2, the raised fabric ratio (%) can be expressed as [(T2-T1)/T1]×100. The thickness is obtained by measuring the thickness under no load using a height gauge (manufactured by Mitutoyo Corporation). In this embodiment, the other surface of the base nonwoven fabric 11 is the non-raised surface 11b, but is not limited thereto, and the fibers may be raised.

Examples of the base nonwoven fabric 11 include nonwoven fabrics such as air-through nonwoven fabrics, point-bonded nonwoven fabrics, spunbonded nonwoven fabrics, and melt-blown nonwoven fabrics, and composite nonwoven fabrics such as spunbonded nonwoven fabric/melt-blown nonwoven fabric laminates and spunbonded nonwoven fabric/melt-blown nonwoven fabric/spunbonded nonwoven fabric laminates. Among these nonwoven fabrics, air-through nonwoven fabrics are preferred from the viewpoint of increasing bulk, etc.

The thickness of the base nonwoven fabric 11 is not particularly limited, but from the viewpoint of a balance between wearing comfort and absorbency, it is in the range of 0.3 mm to 11.0 mm, 0.5 mm to 5.0 mm, or 0.5 mm to 2.0 mm. The basis weight of the base nonwoven fabric 11 is not particularly limited, but is, for example, in the range of 20 g/ ^m2 to ²⁰⁰ g/m2, 20 g/ ^m2 to 160 g/ ^m2 , or 20 g/ ^m2 to 80 g/ ^m2 .

When an air-through nonwoven fabric is used as the base nonwoven fabric 11, the basis weight of the air-through nonwoven fabric is in the range of 20 g/ ^m2 to 80 g/ ^m2 , and the thickness of the fibers constituting the air-through nonwoven fabric is in the range of 1.6 dtex to 14 dtex, 1.8 dtex to 9.0 dtex, or 2.0 dtex to 6.0 dtex. By adjusting the thickness of the fibers constituting the air-through nonwoven fabric to the above range, the superabsorbent polymer 12 is easily dispersed and fixed between the raised fibers 11x of the air-through nonwoven fabric, and the uniform dispersion of the superabsorbent polymer 12 on the raised surface 11a is improved.

(Superabsorbent polymer)
The superabsorbent polymer 12 is not particularly limited as long as it can absorb urine and prevent backflow, and examples thereof include polyacrylates, polyaspartates, (starch-acrylic acid) graft copolymers, (acrylic acid-vinyl alcohol) copolymers, (isobutylene-maleic anhydride) copolymers, and saponified products thereof. Among these, polyacrylates are preferred from the viewpoint of absorption per weight, and sodium polyacrylate is more preferred. The basis weight of the superabsorbent polymer 12 on the raised surface 11a of the superabsorbent sheet 10 (or base nonwoven fabric 11) is, for example, in the range of 150 g/ ^m2 or more and 800 g/ ^m2 or less.

In addition, by avoiding the use of finely powdered superabsorbent polymer 12 that has poor fluidity as a powder, it is preferable to use particulate superabsorbent polymer 12 having a median particle diameter as the superabsorbent polymer 12 in order to improve basic absorption performance and reduce the rough feel caused by the hardness of the superabsorbent sheet 10. The median particle diameter is, for example, in the range of 50 μm to 600 μm or 100 μm to 500 μm.

The superabsorbent polymer 12 is preferably fixed and supported between the raised fibers 11x of the raised surface 11a of the base nonwoven fabric 11 by the hot melt adhesive, and when the basis weight of the base nonwoven fabric 11 is relatively low, the hot melt adhesive functions particularly effectively to reinforce the fixed support of the superabsorbent polymer 12. In addition, from the viewpoint of not impairing the absorbency of the superabsorbent polymer 12 and not impairing the feel on the skin when worn, the content of the hot melt adhesive is, for example, in the range of 10 g/m ² or less. As the hot melt adhesive, those having a melting point of 100°C or more and 180°C or less can be used without any particular limitation, and examples thereof include synthetic rubber-based hot melt adhesives such as styrene-butadiene-styrene copolymers and styrene-isoprene-styrene copolymers, and olefin-based hot melt adhesives such as ethylene-vinyl acetate copolymers. As a method for applying the hot melt adhesive, known methods such as the curtain coat method and spiral method in which the hot melt adhesive in a molten state is applied from a nozzle in a non-contact manner, and the slot method in which the hot melt adhesive is applied in a contact manner can be used.

(hydrophilic sheet)
As described above, the hydrophilic sheet 20, which covers in a C-fold structure the raised surface 11a of the base nonwoven fabric 11 on which the superabsorbent polymer 12 is fixed, includes a pulp-containing nonwoven fabric having a bending stiffness (bending rigidity) of 0.02 gf· ^cm2 /cm or more or a range of 0.02 gf· ^cm2 /cm to 0.6 gf· ^cm2 /cm and a wet strength (tensile strength when wet) of 10 N/50 mm or more or a range of 10 N/50 mm to 70 N/50 mm. Here, the bending stiffness and wet strength are values measured by the methods described below.

If the bending stiffness of the hydrophilic sheet 20 is less than 0.02 gf· ^cm2 /cm and/or the wet strength is less than 10 N/50 mm, the rigidity of the absorbent 1 decreases and the absorbent 1 tends to be easily torn when repeatedly absorbing body fluids or when removed from the body after absorbing body fluids. If the bending stiffness of the hydrophilic sheet 20 exceeds 0.6 gf· ^cm2 /cm and/or the wet strength exceeds 70 N/50 mm, the absorbent 1 becomes too stiff, which reduces the wearability and fit of the absorbent article 50 and tends to cause a large sense of discomfort when worn.

By using a pulp-containing nonwoven fabric having the bending stiffness and wet strength in the above-mentioned range as the hydrophilic sheet 20, the absorbent body 1 maintains its thinness while being not too soft and having appropriate flexibility and rigidity, improving the wearing comfort and fit, and the strength of the absorbent body 1 after absorbing bodily fluids is increased, and when the absorbent article 50 is removed from the body during wearing or after absorbing bodily fluids, the absorbent body 1 does not tear or break, and can be removed cleanly. In addition, as described above, the absorbent body 1 has appropriate rigidity and is very unlikely to tear even if the operating speed is increased during production, so that production efficiency and yield can be improved. In addition, for example, hot melt adhesive or heat embossing can be used to bond the raised surface 11a of the base nonwoven fabric 11 to the hydrophilic sheet 20. By adhering the hydrophilic sheet 20 to the raised surface 11a of the base nonwoven fabric 11, it is possible to prevent the superabsorbent polymer 12 from leaking out of the superabsorbent sheet 10, and also to improve the feel against the skin when worn.

(Pulp-containing nonwoven fabric)
The pulp-containing nonwoven fabric used as the hydrophilic sheet 20 includes a nonwoven fabric and a pulp fiber web laminated on at least one surface of the nonwoven fabric (first embodiment of the pulp-containing nonwoven fabric). In this embodiment, the pulp-containing nonwoven fabric is preferably arranged so that the pulp fiber web, which contributes to, for example, the bodily fluid diffusibility in the absorbent body 1, faces the raised surface 11a of the base nonwoven fabric 11, and the nonwoven fabric, which contributes to, for example, imparting strength to the absorbent body 1, faces outward.

A preferred pulp-containing nonwoven fabric includes a nonwoven fabric and a pulp fiber web integrated with at least one surface of the nonwoven fabric (second embodiment of the pulp-containing nonwoven fabric). Here, "integrated" means that the nonwoven fabric and the pulp fiber web are in a state in which they do not partially peel off from each other before and after use of the absorbent article, and their functions are not significantly reduced. The basis weight of the nonwoven fabric is, for example, in the range of 7 g/ ^m2 to 30 g/ ^m2 , and the basis weight of the pulp fiber web is, for example, in the range of 30 g/ ^m2 to 50 g/ ^m2 . By setting the basis weights of the nonwoven fabric and the pulp fiber web in the above ranges, it becomes easy to adjust the basis weight of the pulp-containing nonwoven fabric to an appropriate range described later.

Among pulp-containing nonwoven fabrics, those integrated by hydroentanglement are preferred (third embodiment of pulp-containing nonwoven fabric). The integrated product is, for example, a pulp-containing nonwoven fabric in which pulp fibers are entangled and integrated by a water jet without using a binder on the surface of the nonwoven fabric to form a pulp fiber web. In such a pulp-containing nonwoven fabric, the fibers constituting the nonwoven fabric and the pulp fibers are entangled on one surface of the nonwoven fabric to form a pulp fiber web, and some of the pulp fibers penetrate the nonwoven fabric in the thickness direction and are exposed on the other surface, so that the nonwoven fabric and the pulp fiber web are extremely firmly bonded together (fourth embodiment of pulp-containing nonwoven fabric).

The pulp fibers used here are not particularly limited, but examples include coniferous bleached kraft pulp (hereinafter also referred to as "NBKP") such as radiata pine, slash pine, southern pine, lodgepole pine, spruce, and Douglas fir. NBKP can be used alone or in combination of two or more types. The nonwoven fabric to be laminated to the pulp fiber web is not particularly limited, but from the viewpoint of the strength and liquid permeability of the entire pulp-containing nonwoven fabric, a spunbond nonwoven fabric composed of synthetic resin fibers is preferable, a spunbond nonwoven fabric containing polypropylene fibers as the synthetic resin fibers is more preferable, and a spunbond nonwoven fabric composed of polypropylene fibers is even more preferable.

In the pulp-containing nonwoven fabric, the weight ratio of the nonwoven fabric to the pulp fiber web (nonwoven fabric/pulp fiber web) is, for example, in the range of 40/60% by weight or more and 10/90% by weight or less. If the content of the pulp fiber web is less than 60% by weight, the pulp-containing nonwoven fabric tends to have poor texture and sweat absorption and tends to become stuffy, and if the content of the pulp fiber web is more than 90% by weight, the pulp-containing nonwoven fabric tends to become hard. The nonwoven fabric to be integrated with the pulp fiber web is not particularly limited, but from the viewpoints of support for the pulp fiber web, the strength, softness, texture, etc. of the entire pulp-containing nonwoven fabric, a spunbond nonwoven fabric is preferred, a spunbond nonwoven fabric containing polypropylene fibers is more preferred, and a spunbond nonwoven fabric made of polypropylene fibers is even more preferred.

From the viewpoint of the thickness and strength of the product, the basis weight of the pulp-containing nonwoven fabric is, for example, in the range of 30 g/ ^m2 to 80 g/ ^m2 or in the range of 40 g/ ^m2 to 60 g/ ^m2 . If it is less than 30 g/ ^m2 , the pulp-containing nonwoven fabric becomes too soft, resulting in a decrease in production yield and a tendency to be easily torn after absorbing bodily fluids, whereas if it exceeds 80 g/ ^m2 , the pulp-containing nonwoven fabric becomes too hard and thick, which tends to make the absorbent body 1 hard and impair comfort when worn.

The bending stiffness and wet strength of the pulp-containing nonwoven fabric can be adjusted to the desired values by, for example, appropriately selecting the material, thickness, basis weight, and weight ratio of the pulp fiber web or nonwoven fabric.

<Method of manufacturing absorbent body>
The manufacturing method of the absorbent body 1 is not particularly limited, but the following method can be mentioned as an example. One side surface of the base nonwoven fabric 11 is raised using a rotary saw blade or needle punch. Then, the highly absorbent polymer 12 is fixed and supported between the raised fibers 11x of the raised surface 11a of the base nonwoven fabric 11 by hot melt adhesive or the like. Then, the raised surface 11a of the base nonwoven fabric 11 and the hydrophilic sheet 20 are bonded by hot melt adhesive or the like, and the non-raised surface 11b is placed inside and folded in a C shape, and one end surface 20a and the other end surface 20b in the width direction of the hydrophilic sheet 20, and one end surface 1A and the other end surface 1B in the width direction of the base nonwoven fabric 11 are respectively opposed in the width direction on the non-skin side of the top sheet 25, to obtain the absorbent body 1. The crease of the C fold may be configured to draw a smooth arc or may be configured to be angular.

<Second embodiment of absorbent body>
FIG. 5 is a schematic cross-sectional view showing the absorbent body 2. The absorbent body 2 is a modified example of the absorbent body 1. The highly absorbent sheet 15 as the absorbent body 2 uses the same base nonwoven fabric 11, highly absorbent polymer 12, and hydrophilic sheet (pulp-containing nonwoven fabric) 20 as the absorbent body 1, and like the highly absorbent sheet 10, the hydrophilic sheet 20 is bonded to the raised surface 11a of the base nonwoven fabric 11, and then the base nonwoven fabric 11 is folded in a C shape with the non-raised surface 11b of the base nonwoven fabric 11 facing the non-skin side of the top sheet 25, and the one end surface 1A and the other end surface 1B in the width direction of the base nonwoven fabric 11 are opposed to each other on the non-skin side of the top sheet 25, and the one end surface 20a and the other end surface 20b in the width direction of the hydrophilic sheet 20 are stretched in the width direction to form an overlapping region. The overlapping region is fixed by the adhesive layer 16, but is not limited to this embodiment and may not be fixed. For example, the above-mentioned hot melt adhesive can be used to form the adhesive layer 16.

In addition, although the opening of the absorbent 2 is blocked by the overlapping region of the hydrophilic sheet 20, the opposing space in the width direction between one end face 1A and the other end face 1B of the base nonwoven fabric 11 is a slit space, and the groove portion (or hollow portion) 21 has the non-raised surface 11b of the base nonwoven fabric 11 as a bottom surface. Since the hydrophilic sheet 20 blocking the opening has excellent bodily fluid permeability and bodily fluid diffusion properties, the groove portion 21 cooperates with the hydrophilic sheet 20 and its overlapping region to improve the uniform diffusion of bodily fluids and further improve the repeated absorption rate. In addition, the absorbent 2 has a partially two-layered base nonwoven fabric 11 that improves cushioning and fit, as in the absorbent 1, and this, combined with the space of the groove portion 21, results in an extremely good wearing comfort and fit.

The absorbent body 2 described above has the same longitudinal and width dimensions as the absorbent body 1, and can be manufactured in the same manner as the absorbent body 1. In addition, in the absorbent bodies 1 and 2, the C-fold creases are configured to be curved so as to draw smooth arcs as shown in Figures 4 and 5, but are not limited to this and may be configured to have angular creases. In the absorbent article 50 of this embodiment, the absorbent body 2 can be used in place of the absorbent body 1.

(Back seat)
The back sheet 30 may be formed using a liquid-impermeable substrate that prevents the body fluid held by the absorbent 1 from wetting clothing, and examples of the substrate include a resin film and a composite sheet that is a laminate of a resin film and a nonwoven fabric. The nonwoven fabric used in the composite sheet is not particularly limited in its manufacturing method, and examples thereof include spunbond nonwoven fabric, meltblown nonwoven fabric, composite nonwoven fabric that is a laminate of spunbond nonwoven fabric/meltblown nonwoven fabric, composite nonwoven fabric that is a laminate of spunbond nonwoven fabric/meltblown nonwoven fabric/spunbond nonwoven fabric, composite materials that are a laminate of two or more of these, and the like. Examples of the resin film include films of polyester, polyvinyl alcohol, polyethylene, polypropylene, etc., and composite films of polyethylene and polypropylene.

The basis weight of the back sheet 30 is, for example, in the range of 15 g/ ^m2 to 40 g/ ^m2 in terms of strength and processability. In addition, from the viewpoint of preventing stuffiness during wearing, the back sheet 30 is preferably breathable. In order to impart breathability to the back sheet 30, for example, a method of blending a filler into a resin film, a method of embossing the back sheet 30 to perforate holes, etc. can be used. Here, an example of the filler is calcium carbonate, and the filler can be blended according to a known method.

(3D gathers)
1, the absorbent article 50 includes a pair of three-dimensional gathers 40 near both side edges of the skin side of the top sheet 25 along the longitudinal direction of the absorbent article 50 in order to prevent, for example, lateral leakage of bodily fluids excreted by the user. The three-dimensional gathers 40 in this embodiment have one widthwise end fixed to both side edges of the skin side of the back sheet 30, a widthwise intermediate portion fixed to both side edges of the skin side of the top sheet 25, and the other widthwise end 40a serving as a free end 40a that is not fixed to the top sheet 25. An elastic stretchable member (not shown) is disposed along the longitudinal direction near the free end 40a, which gives the free end 40a an upstanding property and allows it to be deformed to fit the body shape of the wearer.

The fixed position of one widthwise end of the three-dimensional gathers 40 is not limited to this embodiment, and examples include near both widthwise ends of the non-skin side of the backsheet 30, near both widthwise ends of a bag in which the edges of the topsheet 25 and the backsheet 30 are partially or entirely joined and the absorbent body 1 is housed, and near both widthwise ends of the skin side of the topsheet 25. Note that the absorbent article of this embodiment also includes embodiments that do not include three-dimensional gathers.

As the sheet member constituting the three-dimensional gathers 40, any water-repellent and/or liquid-impermeable nonwoven fabric formed from hydrophobic fibers can be used without any particular limitation, such as spunbond nonwoven fabric, meltblown nonwoven fabric, and composite nonwoven fabric that is a laminate of spunbond nonwoven fabric/meltblown nonwoven fabric/spunbond nonwoven fabric. As the elastic stretch member, any common product in this field can be used without any particular limitation, such as polyurethane thread, strip-shaped polyurethane film, thread-shaped or strip-shaped natural rubber, etc.

(Transfer sheet)
In this embodiment, a transfer sheet (not shown) may be provided. The transfer sheet is disposed, for example, between the top sheet 25 and the absorbent body 1. The transfer sheet is not particularly limited as long as it is a liquid-permeable substrate, and examples thereof include nonwoven fabrics such as air-through nonwoven fabrics, thermal bond nonwoven fabrics, and spunbond nonwoven fabrics, composite nonwoven fabrics in which the same or different types of nonwoven fabrics are laminated, such as thermal bond nonwoven fabric/spunbond nonwoven fabric laminates, foamed films made of urethane foam, polyethylene foam, and composite sheets which are laminates of two or more of these. Among these, air-through nonwoven fabrics are preferred from the viewpoint of preventing the transfer of body fluids to the three-dimensional gathers 40. The basis weight of the transfer sheet is, for example, in the range of 20 g/m ² or more, or in the range of 20 g/m ² or more and 60 g/m ² or less.

<Method of manufacturing absorbent articles>
The absorbent article 50 can be manufactured by a known manufacturing method, for example, a manufacturing method including a step of arranging the absorbent body 1 or 2 between the top sheet 25 and the back sheet 30, a step of fixing the top sheet 25 and the back sheet 30 partially or entirely around the periphery using a hot melt adhesive, heat embossing, ultrasonic embossing, high frequency embossing, or the like, and a step of providing three-dimensional gathers 40 at predetermined positions on the back sheet 30 and the top sheet 25. When the absorbent article 50 is a urine absorption pad or a light incontinence pad, it may be individually packaged in a package and then folded in thirds in the longitudinal direction. Leg gathers, waist gathers, side flaps, and the like may be provided as necessary.

The present invention has been described above using an embodiment, but it goes without saying that the technical scope of the present invention is not limited to the scope of the invention described in the above embodiment, and it is clear to those skilled in the art that various modifications and improvements can be made to the above embodiment. Furthermore, it is clear from the description of the claims that forms incorporating such modifications or improvements can also be included in the technical scope of the present invention.

The present embodiment will be described in detail below with reference to examples and comparative examples. Note that the present embodiment is not limited to the examples shown below.

Example 1
First, an air-through nonwoven fabric (basis weight 30 g/ ^m2 , bending stiffness 0.018 gf· ^cm2 /cm, width dimension 90 mm, length dimension 300 mm) was prepared as a base nonwoven fabric, and one side surface of the base nonwoven fabric was physically raised with a rotary saw blade (thickness after raising 1.2 mm, raising rate 25%). A superabsorbent polymer was dispersed between the fibers of the raised part of the base nonwoven fabric (basis weight 300 g/ ^m2 ) and fixed and supported by a hot melt adhesive. Furthermore, a pulp-containing nonwoven fabric (width dimension 140 mm, length dimension 300 mm) shown in Table 1 was prepared as a hydrophilic sheet, and the raised surface side of the base nonwoven fabric on which the superabsorbent polymer was fixed and supported was bonded to a hydrophilic sheet coated with a hot melt adhesive. Next, the hydrophilic sheet was folded inwards in thirds, and both ends of the hydrophilic sheet were overlapped above the non-raised surface of the base nonwoven fabric, and the overlapping areas were fixed with a hot melt adhesive. The hydrophilic sheet covered the entire raised surface, both widthwise end surfaces, and the entire non-raised surface of the base nonwoven fabric, thereby obtaining an absorbent body of Example 1 having the structure shown in Figure 5.

Next, the absorbent article of Example 1 was produced using an air-through nonwoven fabric (basis weight 25 g/ ^m2 ) as the top sheet, an air-through nonwoven fabric (basis weight 30 g/ ^m2 ) as the transfer sheet, an absorbent with the napped surface facing the back sheet, a breathable polyethylene sheet (basis weight 30 g/ ^m2 ) as the liquid-impermeable back sheet, and a composite nonwoven fabric (basis weight 15 g/ ^m2 ) that is a laminate of spunbond nonwoven fabric/meltblown nonwoven fabric/spunbond nonwoven fabric as the three-dimensional gathers.

(Examples 2 to 4)
The absorbent bodies and absorbent articles of Examples 2 to 4 were prepared in the same manner as in Example 1, except that the pulp-containing nonwoven fabric shown in Table 1 was used as the hydrophilic sheet.

Example 5
An absorbent body and absorbent article of Example 5 having the structure shown in Fig. 4 were produced in the same manner as in Example 1, except that a pulp-containing nonwoven fabric (width dimension 100 mm) shown in Table 1 was used as the hydrophilic sheet, and the hydrophilic sheet was folded inward in three by folding 20 mm each on the left and right sides toward the center, leaving a central portion of 60 mm, and fixed with a hot melt adhesive. In this absorbent body, the non-raised surface of the base nonwoven fabric was exposed at the widthwise center of the base nonwoven fabric so as to extend in the longitudinal direction by a width of 20 mm.

(Comparative Example 1)
An absorbent body and an absorbent article were prepared in the same manner as in Example 1, except that the pulp-containing nonwoven fabric shown in Table 1 was used as the hydrophilic sheet.

(Comparative Example 2)
An absorbent core and an absorbent article of Comparative Example 2 were prepared in the same manner as in Example 1, except that a spunbond nonwoven fabric shown in Table 1 was used as the hydrophilic sheet.

(Comparative Example 3)
An absorbent core and an absorbent article of Comparative Example 3 were produced in the same manner as in Example 1, except that the crepe paper shown in Table 1 was used as the hydrophilic sheet.

(Comparative Example 4)
The absorbent body and absorbent article of Comparative Example 4 were prepared in the same manner as in Example 1, except that the pulp-containing nonwoven fabric (width dimension 60 mm) shown in Table 1 was used as the hydrophilic sheet and was arranged flat rather than being folded in thirds.

(Comparative Example 5)
A five-layer laminated sheet (all dimensions in the width direction are 60 ^mm ) consisting of air-through nonwoven fabric (basis weight 25 g/ ^m2 )/super absorbent polymer (basis weight 140 g/ ^m2 )/air-through nonwoven fabric (basis weight 30 g/ ^m2 )/super absorbent polymer (basis weight 140 g/m2)/spunlace nonwoven fabric (basis weight 20 g/ ^m2 ) was used as the absorbent body of Comparative Example 5, and this was interposed between the same top sheet and back sheet as in Example 1 to produce the absorbent article of Comparative Example 5. Note that the nonwoven fabric used in Comparative Example 5 was not subjected to a raising treatment like the base nonwoven fabric used in Example 1.

[Measurement item]
The thickness, absorption rate, and return amount were measured for each of the absorbent bodies and absorbent articles obtained in Examples 1 to 5 and Comparative Examples 1 to 5. The results are shown in Table 1.
(Thickness)
The thickness of the absorbent body at the center was measured under no load and under a load of 35 gf/ ^cm2 .
(Absorption rate)
In each of the absorbent articles of Examples 1 to 5 and Comparative Examples 1 to 5, 40 ml of 0.9% by mass saline (37°C) is poured from a tube with an inner diameter of 30 mm under a pressure of ⁴⁶ g/cm2, and the time (seconds) until the saline is absorbed into the absorbent surface is measured as the first absorption speed. After 3 minutes, 40 ml of 0.9% by mass saline (37°C) is poured again, and the time (seconds) until the saline is absorbed into the absorbent surface is measured as the second absorption speed. The smaller the value, the better the absorbency.
(Reverse flow amount)
100 ml of physiological saline was poured into each of the absorbent articles of Examples 1 to 5 and Comparative Examples 1 to 5. 90 seconds after pouring, a filter paper was pressed against the absorbent surface with a load of 35 gf/ ^cm2 , and the amount of water that returned to the filter paper in 1 minute (wet-back amount) was measured. The smaller the amount of return, the drier the absorbent was.

Furthermore, for each of the absorbent articles of Examples 1 to 5 and Comparative Examples 1 to 5, evaluation of absorbent core breakage, evaluation of operability, and sensory evaluation were performed and evaluated according to the following evaluation criteria. The results are shown in Table 1.
(Absorbent Breakage Evaluation)
Each of the absorbent articles of Examples 1 to 5 and Comparative Examples 1 to 5 was placed on a laboratory bench, and 100 ml of saline was poured into it. 10 minutes after pouring, a 12 kg roller was used to roll the article back and forth twice at a speed of 30 mm/sec, and the absorbent body inside the absorbent article was then confirmed.
◯: The absorbent body was not torn. ×: The absorbent body was torn and the SAP was protruding. (Operational efficiency)
○: Normal production was possible without slowing down operations.
△: The operating speed was slower than normal by 1% to 10%.
×: The operating speed was reduced by more than 10% compared to normal.
(sensory evaluation)
Eight panelists wore each of the absorbent articles of Examples 1 to 5 and Comparative Examples 1 to 5, and conducted a sensory evaluation of the wearing comfort (fit, softness) and absorbency (presence or absence of leakage to the outside of the absorbent article) by selecting either "good" or "bad." The wearers used the articles for eight hours and performed evaluations during daily activities, and the results are shown in Table 1.
〇: When the number of wearers who chose "good" is between 6 and 8. △: When the number of wearers who chose "good" is between 3 and 5. ×: When the number of wearers who chose "good" is 1 or 2, or when there is no wearer who chose "good".

The bending stiffness (bending rigidity) and wet strength of each hydrophilic sheet were measured by the following method.
(Bending strength)
The bending stiffness (bending rigidity) was measured by inserting a sample (100 mm x 100 mm) into the fixed chuck and movable chuck of a bending tester (product name: KES-FB2, manufactured by Kato Tech Co., Ltd.). The movable chuck moved to the maximum positive curvature of +2.5 cm ^-1 , reversed, passed through a curvature of 0, and then moved to the maximum negative curvature of -2.5 cm ^-1 , reversed, and ended at a curvature of 0, thus obtaining a reciprocating curve of the bending moment for one cycle of curvature. In the reciprocating curve of the bending moment, the average value of the slope between the curvatures of 0.5 cm ^-1 and 1.5 cm ^-1 and the slope between the curvatures of -0.5 cm ^-1 and -1.5 cm ^-1 was taken as the bending stiffness.
(Wet strength, wet tensile strength)
The wet strength (tensile strength when wet) was measured in the CD direction of each hydrophilic sheet based on the tensile test method of JIS8135.

1, 2 Absorbent body 10, 15 Highly absorbent sheet 11 Base nonwoven fabric 11a Raised surface 11b Non-raised surface 11x Raised fiber 1A, 1B End surface (both end surfaces in the width direction of the base nonwoven fabric)
12 Superabsorbent polymer 16 Adhesive layer 20 Hydrophilic sheet 20a, 20b End surfaces (both widthwise end surfaces of the hydrophilic sheet)
25 Top sheet 30 Back sheet 40 Standing gather 40a Free end of standing gather 50 Absorbent article

Claims (5)

An absorbent article comprising a liquid-permeable top sheet, a liquid-impermeable back sheet, and an absorbent body disposed between the top sheet and the back sheet,
The absorbent body is
a base nonwoven fabric having a raised surface and a non-raised surface, the non-raised surface being disposed so as to face the top sheet;
a highly absorbent polymer fixedly supported between the raised fibers on the raised surface of the base nonwoven fabric;
a hydrophilic sheet covering the raised surface of the base nonwoven fabric;
The hydrophilic sheet is
The nonwoven fabric includes a pulp-containing nonwoven fabric having a bending stiffness of 0.02 gf cm ² /cm or more and 0.60 gf cm ² /cm or less and a wet strength of 10 N/50 mm or more and 70 N/50 mm or less,
The pulp-containing nonwoven fabric comprises a spunbonded nonwoven fabric containing polypropylene fibers and a pulp fiber web integrated with at least one surface of the spunbonded nonwoven fabric, and is an integrated product in which the fibers constituting the spunbonded nonwoven fabric and the pulp fibers constituting the pulp fiber web are entangled with each other;
the absorbent body has a three-dimensional shape inwardly folded in three so that the non-raised surface of the highly absorbent sheet is on the inside and both widthwise end surfaces of the base nonwoven fabric face each other on the non-skin side of the top sheet,
An absorbent article, wherein the distance between both end faces in the width direction of the base nonwoven fabric is 10% or more and 90% or less of the width direction dimension of the absorbent body. The absorbent article according to claim 1, wherein the absorbent has a groove portion with the non-raised surface as a bottom surface and a slit space between the two widthwise end faces of the base nonwoven fabric, and the hydrophilic sheet is stretched in the width direction so that both widthwise end portions overlap covering the slit space of the groove portion, and the overlapping width dimension is 5% to 50% of the widthwise dimension of the absorbent. The absorbent article according to claim 1 or 2, wherein the pulp-containing nonwoven fabric has a basis weight of 30 g/ ^m2 or more and 80 g/ ^m2 or less. The absorbent article according to any one of claims 1 to 3, wherein the base nonwoven fabric is an air-through nonwoven fabric, the basis weight of the air-through nonwoven fabric is 20 g/ ^m2 or more and 80 g/ ^m2 or less, and the thickness of the fibers constituting the air-through nonwoven fabric is 1.6 dtex or more and 14 dtex or less. The absorbent article according to any one of claims 1 to 4, wherein the basis weight of the superabsorbent polymer in the superabsorbent sheet is 150 g/ ^m2 or more and 800 g/ ^m2 or less.

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