JP7470594B2 - Absorbent articles - Google Patents

Description

The present invention relates to an absorbent article.

In general, absorbent articles such as light incontinence pads, pants-type disposable diapers, and tape-fastened disposable diapers are composed of a liquid-permeable top sheet, a liquid-impermeable back sheet, and an absorbent body placed between the two sheets. As a result, bodily fluids such as urine are absorbed into the absorbent body through the top sheet, and the back sheet prevents them from leaking to the outside. Since the absorbent body has such functions, it is required that the absorbent body has a suitable fit that adheres closely to the body both before and after absorbing bodily fluids. In addition, various proposals have been made for absorbent articles to improve the absorbency of bodily fluids, improve the wearing comfort of the wearer, prevent leakage, etc.

For example, there is a technique for improving the absorption performance such as wetback and absorption speed by using an open foam polyurethane in a predetermined portion of an absorbent article. For example, Patent Document 1 discloses an absorbent article using an open foam polyurethane, which comprises a liquid-permeable top sheet, a second sheet placed on the non-skin side of the top sheet, an absorbent body, and a liquid-impermeable back sheet, and the second sheet is made of an open foam polyurethane having an apparent density of 100 kg/m3 or ^more and 200 kg/ ^m3 or less.

JP 2017-164356 A

The absorbent article of Patent Document 1, which has a continuous porous polyurethane body as a second sheet placed close to the wearer's skin, is somewhat effective in preventing liquid backflow such as wet bags and maintaining the absorption rate. However, the use of a continuous porous polyurethane body as a second sheet is not effective in improving the wearing comfort and fit of the absorbent article, and may cause stress or discomfort to the wearer.

Therefore, the present invention has been made in consideration of the above problems, and aims to provide an absorbent article that is excellent in fit and prevention of leakage of bodily fluids, and has a good wearing feel.

The inventors of the present invention have conducted extensive research in light of the above problems. As a result, they have found that the above problems can be solved by placing a soft polyurethane foam as a third sheet between a bulky second sheet and an absorbent body, and setting the adhesive area ratio and adhesive region with a hot melt adhesive within an appropriate range, thereby completing the present invention. Specifically, the present invention provides the following absorbent article.

(1) An absorbent article comprising a liquid-permeable top sheet, a liquid-impermeable back sheet, a second sheet disposed on the non-skin side of the top sheet, and an absorbent body disposed between the second sheet and the back sheet,
The second sheet is a bulky nonwoven fabric having a density of 20 g/ ^cm3 or more and 40 g/cm3 or ^less ,
A third seat including a soft polyurethane foam arranged on a non-skin side of the second seat;
a hydrophilic sheet disposed between the absorbent body and the third sheet and covering the absorbent body;
a first hot melt adhesive layer provided on a skin side of the third sheet and interposed between the second sheet and the third sheet;
and a second hot melt adhesive layer provided on the non-skin side of the third sheet and interposed between the third sheet and the hydrophilic sheet. The first hot melt adhesive layer has an adhesive area ratio of 10% or more and 50% or less on the skin side of the third sheet.
The absorbent article is characterized in that the second hot melt adhesive layer has an unadhesive region having a width of 15 mm or more and 90 mm or less extending longitudinally through the widthwise center of the third sheet and the hydrophilic sheet.
(2) A second aspect of the present invention is the absorbent article according to (1), characterized in that the second sheet is an air-through nonwoven fabric.
(3) A third aspect of the present invention is the absorbent article according to (1) or (2), characterized in that the hydrophilic sheet contains pulp.
(4) A fourth aspect of the present invention is the absorbent article according to any one of (1) to (3), characterized in that the top sheet is an air-through nonwoven fabric.
(5) A fifth aspect of the present invention is an absorbent article described in any one of (1) to (4), characterized in that the absorbent body contains fluff pulp and a superabsorbent polymer, and the ratio of the weight of the superabsorbent polymer to the weight of the entire absorbent body is 40% by weight or more.
(6) A sixth aspect of the present invention is an absorbent article according to any one of (1) to (5), characterized in that the basis weight of the third sheet is 70 g/ ^m2 or more and 300 g/ ^m2 or less.
(7) A seventh aspect of the present invention is an absorbent article according to any one of (1) to (6), characterized in that the compression stiffness LC of the third sheet is 0.5 or more and 0.9 or less.
(8) An eighth aspect of the present invention is an absorbent article according to any one of (1) to (7), characterized in that the compression recovery RC of the third sheet is 15% or more and 60% or less.

The present invention provides an absorbent article that is excellent in fit and prevention of leakage of bodily fluids, and has a good wearing comfort.

1 is a schematic plan view showing a configuration of an absorbent article according to a first embodiment of the present invention. 2 is a schematic cross-sectional view in the width direction taken along the X ₁ -X ₁ cutting line shown in FIG. 1 . 1A and 1B are schematic plan views showing configurations of absorbent articles according to second and third embodiments of the present invention, where (a) shows the second embodiment and (b) shows the third embodiment.

In this specification, the same elements in each embodiment are denoted by the same reference numerals, and the description thereof is omitted. The absorbent article 1 is worn when the absorbent article 1 is worn on the body, regardless of whether it is before or after absorbing bodily fluids. In the absorbent article 1, the longitudinal direction is the direction indicated by the reference numeral Y in the figure, which extends from the front to the back of the wearer when the absorbent article 1 is worn, the width direction is the direction indicated by the reference numeral X in the figure, which is perpendicular to the longitudinal direction, and the thickness direction is the direction indicated by the reference numeral Z in the figure, in which the components of the absorbent article 1 are stacked. The skin side is the side that is placed on the skin side of the wearer when the absorbent article 1 is worn, and the non-skin side is the side that is placed on the clothing side of the wearer when the absorbent article 1 is worn. Bodily fluids refer to liquids discharged from the body to the outside, such as urine, blood, and water in loose stools.

<Absorbent article (first embodiment)>
Hereinafter, an absorbent article 1 according to the present embodiment will be described with reference to the accompanying drawings. Figures 1 and 2 show an absorbent article 1 according to a first embodiment. These drawings do not stipulate the shape, dimensions, size relationship, etc. of each component in the absorbent article 1.

The absorbent article 1 of this embodiment can be used as various absorbent articles for babies or adults, such as light incontinence pads, urine absorption pads, pants-type paper diapers, tape-fastened paper diapers, etc. Among these, use as light incontinence pads, urine absorption pads, etc. is preferable. Various paper diapers as outerwear may be combined with the absorbent article 1 as innerwear. The longitudinal dimension (hereinafter also simply referred to as "length") and width dimension (hereinafter also simply referred to as "width") of the absorbent article 1 are not particularly limited, but are, for example, in the range of 100 mm or more and 800 mm or less, and 50 mm or more and 500 mm or less. By adjusting the dimensions of the absorbent article 1 to the above ranges, absorbent articles for various uses can be easily obtained.

As shown in Figs. 1 and 2, the absorbent article 1 includes a liquid-permeable top sheet 10 that is positioned closest to the wearer's skin when the absorbent article 1 is worn, a liquid-impermeable back sheet 30 that is positioned opposite the top sheet 10 and is positioned closest to the wearer's skin when the absorbent article 1 is worn, a second sheet 40 that is positioned on the non-skin side of the top sheet 10, a third sheet 50 that is positioned on the non-skin side of the second sheet 40, a hydrophilic sheet 60 that is positioned on the non-skin side of the third sheet 50, an absorbent body 20 that is positioned between the hydrophilic sheet 60 and the back sheet 30, and a pair of three-dimensional gathers 70 that are provided on the skin side of the top sheet 10. The hydrophilic sheet 60 covers the absorbent body 20, and the absorbent body 20 absorbs and retains body fluids such as urine that have permeated the top sheet 10. Leg gathers, waist gathers, side flaps, etc. can be provided as appropriate depending on the purpose and type of the absorbent article 1.

According to this embodiment, between the top sheet 10 and the absorbent body 20, a second sheet 40 which is a bulky nonwoven fabric, a third sheet 50 which includes a soft polyurethane foam sheet which stretches in all directions, and a hydrophilic sheet 60 which covers the skin side of the absorbent body 20 are arranged in this order from the top sheet 10 side to the absorbent body 20 side, and if necessary, a first adhesive layer 80 (Fig. 2) made of hot melt adhesive is provided in a predetermined area and/or a second adhesive layer 91 made of hot melt adhesive is arranged in a predetermined position (Fig. 2), thereby providing an absorbent article 1 which has improved softness and fit, provides a good wearing feeling, sufficiently prevents leakage and backflow of body fluids, and has excellent absorption performance such as repeated absorption speed and body fluid absorption amount.

Below, each sheet-like component will be described in more detail in the following order: top sheet 10, absorbent body 20, back sheet 30, second sheet 40, third sheet 50, hydrophilic sheet 60, first hot melt adhesive layer 80, second hot melt adhesive layer 91, and three-dimensional gathers 70. Note that these components may have a three-dimensional structure other than a sheet shape.

(Top sheet)
The top sheet 10 may be formed from a substrate having liquid permeability that allows bodily fluids to move to the absorbent 20. Examples of the substrate include nonwoven fabrics such as air-through nonwoven fabrics, thermal bond nonwoven fabrics, and spunbond nonwoven fabrics, composite nonwoven fabrics laminated with thermal bond/spunbond, foamed films such as urethane foam, and composite sheets laminated with these. Among these, air-through nonwoven fabrics are preferred from the viewpoints of bodily fluid diffusion, liquid return amount, and skin feel. In addition, the top sheet 10 may be embossed or perforated on the surface according to a known method in order to improve liquid permeability. In addition, in order to reduce irritation to the skin, the top sheet 10 may contain one or more of lotions, antioxidants, anti-inflammatory components, pH adjusters, antibacterial agents, moisturizers, and the like.

From the viewpoints of strength, processability, and liquid return, the basis weight of the top sheet 10 is in the range of 18 g/m ² to 40 g/m ^2. There are no particular limitations on the shape of the top sheet 10, but it may have any shape that covers all or part of the absorbent body 20, which is necessary to guide bodily fluids to the absorbent body 20 without leakage.

(Second seat)
The second sheet 40 is disposed on the non-skin side of the top sheet 10, more specifically, between the top sheet 10 and the third sheet 50. By disposing the second sheet 40, cushioning properties are increased, and the fit and wearing comfort are improved, as well as the bodily fluid diffusion properties of the absorbent article 1 are improved.

The base material of the second sheet 40 is a bulky nonwoven fabric having a density of 20 g/cm ³ to 40 g/cm ³ , which has a faster permeability rate of bodily fluids than the top sheet 10 and quickly diffuses bodily fluids to the third sheet 50. An air-through nonwoven fabric is preferable as the nonwoven fabric. The thickness of the second sheet 40 is, for example, in the range of 0.1 mm to 4 mm, and the basis weight is, for example, in the range of 20 g/m ² to 60 g/m ² , or in the range of 22 g/m ² to 37 g/m ^2. If the thickness is less than 0.1 mm, or the basis weight is less than 20 g/m ² or more than 60 g/m ² , bodily fluids do not sufficiently diffuse over the entire skin side of the third sheet 50, and the wearing comfort tends to be deteriorated. In addition, the shape of the second sheet 40 is not particularly limited, but in a preferred embodiment, it is a shape that can completely cover the surface of the third sheet 50 so that bodily fluids diffuse into the third sheet 50.

(Third seat)
The third sheet 50 is disposed on the non-skin side of the second sheet 40, more specifically between the second sheet 40 and the hydrophilic sheet 60. The third sheet 50 is a sheet containing soft polyurethane foam. The soft polyurethane foam may be an open-cell foam or a closed-cell foam, but an open-cell foam is preferable from the viewpoint of exhibiting the flexibility of the soft polyurethane foam in all directions and improving the fit to the crotch area of the wearer. The fact that the soft polyurethane foam is an open-cell foam can be easily confirmed by cutting the soft polyurethane foam and observing the cut surface under a microscope. Examples of sheets containing soft polyurethane foam include sheets made of soft polyurethane foam, sheets formed by dispersing particles, fibers, etc. made of soft polyurethane foam in other synthetic resins, and sheets in which particles or fibers made of soft polyurethane foam are mixed with cloth (nonwoven fabric, knitted fabric, woven fabric, etc.) made of fibers. Among these, sheets made of soft polyurethane foam are preferable, and sheets made of soft polyurethane foam, which is an open-cell foam, are more preferable.

The apparent density of the flexible polyurethane foam is, for example, in the range of 0.01 g/ ^cm3 or more and 0.3 g/ ^cm3 . The expansion ratio of the flexible polyurethane foam is, for example, 10 times or more and 60 times or less. When the apparent density and/or expansion ratio are within the above range, the material tends to be stretchable in all directions. When the expansion ratio is less than 10 times and/or the apparent density is more than 0.3 g/ ^cm3 , the elasticity becomes insufficient and it tends to be difficult to fit the crotch area of the wearer. When the expansion ratio is more than 60 times and/or the apparent density is less than 0.01 g/ ^cm3 , the strength of the flexible polyurethane foam tends to be easily reduced.

The flexible polyurethane foam preferably has a hydrophilic skeleton surface. Specific examples of flexible polyurethane foams with a hydrophilic skeleton surface include flexible polyurethane foams whose skeleton itself is hydrophilic (the former) and flexible polyurethane foams whose skeleton surface has hydrophilic groups introduced therein (the latter). The former can be obtained, for example, by using a raw material compound containing a polyalkylene oxide polyol as a polyol component. The latter can be obtained by reacting a flexible polyurethane foam with a surfactant, an ethylene oxide compound, or the like, according to a known method.

Whether or not the skeleton surface of a flexible polyurethane foam is hydrophilic can be determined by the following method. First, a flexible polyurethane foam (width 10 mm or more, length 10 mm or more) is left to stand without bending. Then, 10 droplets (0.05 mL) of ion-exchanged water are dropped onto the flexible polyurethane foam, and the time until the water droplets are absorbed by the flexible polyurethane foam is measured. If this time is within 5 seconds, or if 8 or more droplets are absorbed, it is determined to be hydrophilic.

Flexible polyurethane foam can be obtained according to a known manufacturing method, for example, by mixing raw material compounds such as polyols and polyisocyanates, additives such as blowing agents, foam stabilizers, and catalysts, and heating the resulting mixture to foam. Alternatively, a gaseous blowing agent may be injected while reacting the raw material compounds under heating. Alternatively, foaming and sheet molding may be performed simultaneously. By appropriately selecting reaction conditions such as the type of raw material compounds, the type and amount of additives, the heating temperature during foaming, the foaming time, and the pressure during foaming, the properties of the flexible polyurethane foam, such as the foaming ratio, apparent density, compression stiffness LC, and compression recovery RC, can be adjusted.

The basis weight of the soft polyurethane foam of the third sheet 50 is, for example, in the range of 70 g/ ^m2 to 300 g/ ^m2 , or in the range of 80 g/ ^m2 to 200 g/ ^m2 . The thickness of the third sheet 50 is, for example, in the range of 0.5 mm to 3.0 mm, or in the range of 1.0 mm to 2.5 mm. If the thickness is less than 0.5 mm, the third sheet 50 tends to be easily broken, and if the thickness exceeds 3.0 mm, the third sheet 50 tends to be bulky and hard, which may reduce the wearing comfort of the absorbent article 1. In this specification, the thickness of each sheet is not limited to the third sheet 50, and is measured under no-load conditions using a height gauge (manufactured by Mitutoyo Corporation).

(Compression stiffness LC)
The compression stiffness LC of the third sheet 50 is, for example, in the range of 0.5 to 0.9, or in the range of 0.55 to 0.85. If LC is less than 0.5, the sheet tends to be easily twisted when worn. If LC exceeds 0.9, the sheet tends to be hard and stiff when worn. The closer the value of the compression stiffness LC is to 1, the harder the sheet is to compress. The compression stiffness LC is measured using a compression tester KES-G5 (trade name, manufactured by Kato Tech Co., Ltd.) by placing a sample (here, the third sheet 50) on a smooth metal plane and pressing a ² cm2 compressor perpendicular to the sample surface at a constant speed of 0.2 mm/sec.

(Compression recovery RC)
The compression recovery RC of the third sheet 50 is, for example, in the range of 15% to 60% or 20% to 55%. If the RC is less than 15%, the fit is reduced when worn, and a gap is generated between the skin and the product, which tends to make body fluids more likely to leak. If the RC exceeds 60%, the wearing comfort tends to be impaired. The higher the compression recovery RC value, the higher the compression recovery. The compression recovery RC is measured using a compression tester KES-G5 (trade name, manufactured by Kato Tech Co., Ltd.) by placing a sample (here, the third sheet 50) on a smooth metal plane and pressing a 2 cm ² compressor perpendicular to the sample surface at a constant speed of 0.2 mm/sec.

(hydrophilic sheet)
The hydrophilic sheet 60 has a function of covering, for example, the skin-side surface of the absorbent 20, and is disposed on the non-skin side of the third sheet 50, more specifically, between the third sheet 50 and the absorbent 20. As the hydrophilic sheet 50, a sheet commonly used in this field can be used, for example, a pulp-containing base material such as tissue paper or absorbent paper, a spunbonded nonwoven fabric, an airlaid nonwoven fabric, or the like. Among these, for example, from the viewpoint of availability and cost, a pulp-containing base material or an airlaid nonwoven fabric is preferred, and a pulp-containing base material is more preferred. The basis weight of the hydrophilic sheet 60 is, for example, in the range of 10 g/m ² to 60 g/m ² , or in the range of 13 g/m ² to 50 g/m ² .

(First hot melt adhesive layer)
2, in the absorbent article 1, the second sheet 40 and the third sheet 50 are bonded together by a first hot melt adhesive layer 80 provided on the skin side of the third sheet 50. The first hot melt adhesive layer 80 is formed by applying a hot melt adhesive in a predetermined pattern to the skin side of the third sheet 50 by various methods.

At this time, the adhesion area ratio, which is the ratio of the adhesion area of the first hot melt adhesive layer 80 to the area of the skin side of the third sheet 50, is in the range of 10% to 50% or in the range of 20% to 40%. By setting the adhesion area ratio to 10% to 50%, the adhesion area ratio between the second sheet 40 and the third sheet 50 becomes an appropriate area, which suppresses the leakage of body fluids along the surface of the absorbent article 1, and as a result, side leakage and back leakage can be prevented. If the adhesion area ratio is less than 10%, a gap will be generated between the second sheet 40 and the third sheet 50, which will make it easier for body fluids to flow along the surface of the second sheet 40 or the third sheet 50, which will result in side leakage and back leakage, and the body fluid may reach the end of the absorbent article 1 and soil underwear, etc. Also, if the adhesion area ratio exceeds 50%, the liquid permeability will decrease, and the body fluid will not reach the absorbent body 20 quickly, and the body fluid may easily flow along the surface of the absorbent article 1.

(Second Hot Melt Adhesive Layer)
FIG. 3 shows the planar shape of the unbonded region 90 and the second hot melt adhesive layer 91 shown in FIG. 2. For convenience, the absorbent article 2 of the second embodiment shown in FIG. 3(a) and the absorbent article 3 of the third embodiment shown in FIG. 3(b) are taken as the absorbent article 2 of the second embodiment, and the absorbent article 3 of the third embodiment shown in FIG. 3(b). The widthwise cross-sectional views of the absorbent article 2 and the absorbent article 3 taken along the longitudinal center line X ₁ -X ₁ have the same structure. In FIG. 3, the unbonded region 90 and the second hot melt adhesive layer 91 present inside the absorbent article 2 and the absorbent article 3 are shown by solid lines for convenience of explanation. The absorbent article 2 and the absorbent article 3 have the same configuration and the same modifications as the absorbent article 1, except for the unbonded region 90 and the second hot melt adhesive layers 91 arranged on both widthwise outer sides thereof. The second hot melt adhesive layer 91 is formed by applying a hot melt adhesive in a predetermined pattern to the non-skin side of the third sheet 50 by various methods.

As shown in FIG. 3, in the absorbent article 2 and the absorbent article 3, the third sheet 50 and the hydrophilic sheet 60 are bonded by a pair of second hot melt adhesive layers 91 provided to extend in the longitudinal direction near both ends of the width direction of the non-skin side of the third sheet 50. In these embodiments, a strip-shaped unbonded region 90 extending in the longitudinal direction is present between the third sheet 50 and the hydrophilic sheet 60 in the width direction center portion. In the absorbent article 3 , the unbonded region 90 is provided to extend from one end to the other end in the longitudinal direction of the absorbent article 2. In the absorbent article 2 , the unbonded region 90 is provided to extend from one intermediate portion to the other intermediate portion in the longitudinal direction of the absorbent article 2. The planar shape of the unbonded region 90 in this embodiment is rectangular in FIG. 3, but is not limited thereto, and may be, for example, a substantially elliptical shape, a substantially rhombus shape, a rounded rectangle with rounded corners, an oval shape, or the like.

Here, the widthwise center portion may be the widthwise center portion of the region where the third sheet 50 and the hydrophilic sheet 60 overlap in the thickness direction when they are laminated according to the product specifications, but strictly speaking, as shown in Fig. 3, it is the widthwise center portion of the region surrounded by the longest longitudinal length LO centered on the longitudinal center line _X1 - _X1 of the absorbent articles 2, 3 and the longest width WO centered on the widthwise center line _Y1 - _Y1 of the absorbent articles 2, 3. The longest length LO and the longest width WO in the width direction are determined by appropriately selecting the longitudinal dimensions and widthwise dimensions of the third sheet 50 and/or the hydrophilic sheet 60 and their planar shapes.

In this unbonded region 90, the dimension of the maximum width WO in the width direction is, for example, in the range of 15 mm or more, 15 mm or more to 90 mm or less, or 25 mm or more to 70 mm or less. The dimension of the maximum length LO in the longitudinal direction is, for example, in the range of 70 mm or more, or 90 mm or more to 250 mm or less. Since there is an unbonded region 90 with WO of 15 mm or more to 90 mm or less, and the third sheet 50 and the hydrophilic sheet 60 are not bonded at the center of the absorbent article 2, 3, a gap is generated between the third sheet 50 and the hydrophilic sheet 60, resulting in improved bodily fluid diffusion, and the bodily fluid quickly spreads over the entire absorbent body 20 inside the absorbent article 2, 3. If the maximum width WO in the width direction is less than 15 mm, the gap generated between the third sheet 50 and the hydrophilic sheet 60 becomes small, resulting in a decrease in bodily fluid diffusion, and there is a risk that the spread of the bodily fluid over the entire absorbent body 20 will be delayed. Furthermore, if the maximum width WO in the width direction exceeds 90 mm, it may cause the absorbent body 20 to twist or cause liquid to run down the surface of the third sheet 50 or hydrophilic sheet 60, resulting in a decrease in wearing comfort and the risk of side or back leakage.

The areas other than the unbonded areas 90 become the second hot melt adhesive layer 91. The bonded area ratio, which is the ratio of the total bonded area of the second hot melt adhesive layer 91 to the area of the non-skin side of the third sheet 50, is, for example, in the range of 50% or less.

The hot melt adhesive used in the first hot melt adhesive layer 80 and the second hot melt adhesive layer 91 can be any hot melt adhesive with a melting point of 100°C or higher and 180°C or lower, without any particular limitations. Examples of the hot melt adhesive include synthetic rubber hot melt adhesives such as styrene-butadiene-styrene copolymers and styrene-isoprene-styrene copolymers, and olefin hot melt adhesives such as ethylene-vinyl acetate copolymers. Hot melt adhesives can be applied by known methods such as the curtain coat method or spiral method, in which the molten hot melt adhesive is applied from a nozzle in a non-contact manner, or the slot method, in which the adhesive is applied in a contact manner.

(Absorber)
The absorbent body 20 of this embodiment has a longest length dimension LO (FIG. 1) in the longitudinal direction, for example, in the range of 100 mm to 800 mm, 150 mm to 500 mm, or 270 mm to 500 mm. The longest width dimension WO (FIG. 1) in the width direction of the absorbent body 20 is, for example, in the range of 50 mm to 500 mm, 60 mm to 400 mm, or 70 mm to 105 mm. In addition, when the planar shape of the absorbent body 20 is an hourglass shape, the longitudinal dimension is in the range of 180 mm to 480 mm, the width dimensions of the ventral side part and the back side part that contact the wearer's abdomen and back, respectively, are both in the range of 60 mm to 160 mm, and the width dimension of the crotch part that contacts the wearer's crotch is in the range of 50 mm to 140 mm. The absorbent body 20 may be embossed all over or in part. Examples of the shape of the absorber 20 in a plan view include an hourglass shape, an I-shape, a rectangle, a rounded rectangle with rounded corners, and an oval.

(Absorbent Fiber)
The absorbent body 20 contains absorbent fibers and a superabsorbent polymer (hereinafter also referred to as "SAP") as an absorbent base material.
The absorbent fiber is not particularly limited as long as it is used in absorbent products such as sanitary napkins, paper diapers, and urine pads, and examples thereof include fluff pulp, cotton, rayon, acetate, tissue, absorbent paper, hydrophilic nonwoven fabric, etc. Among these, fluff pulp is preferred from the viewpoint of absorbency. Examples of fluff pulp include cotton-like defibrated materials such as wood pulp (e.g., coniferous bleached kraft pulp (N-BKP) such as southern pine and Douglas fir), synthetic fibers, resin fibers, and non-wood pulp. When fluff pulp is used as the absorbent fiber, which is the absorbent base material, in the absorbent body 20, the basis weight of the absorbent fiber is, for example, in the range of 100 g/m ² to 800 g/m ² , or in the range of 325 g/m ² to 615 g/m ² , from the viewpoint of the amount of body fluid absorption and the feel on the skin.

(Superabsorbent polymer)
The superabsorbent polymer is not particularly limited as long as it can absorb body fluids and prevent backflow, and examples thereof include polyacrylates, polyaspartates, (starch-acrylic acid) graft copolymers, (acrylic acid-vinyl alcohol) copolymers, (isobutylene-maleic anhydride) copolymers, and saponification products thereof, etc. Among these, from the viewpoint of the absorption amount per weight, polyacrylates are preferable, and sodium polyacrylate is more preferable.

The basis weight of the SAP contained in the absorbent body 20 is, for example, in the range of 240 g/ ^m2 to 450 g/ ^m2 , or in the range of 245 g/m2 to 445 g/ ^m2 , from the viewpoint of preventing gel blocking and allowing the absorbent body 20 to absorb ^a larger amount of body fluid. In addition, in the absorbent body 20, the ratio of the weight of the superabsorbent polymer to the weight of the fluff pulp, [weight of superabsorbent polymer/(weight of superabsorbent polymer+weight of fluff pulp)]×100(%), is, for example, in the range of 40% by weight or more, in the range of 40% by weight or more to 100% by weight or less, or in the range of 50% by weight or more to 90% by weight or less.

In addition, by avoiding the use of finely powdered superabsorbent polymers that have poor fluidity as a powder, it is possible to improve basic absorption performance and reduce the rough feel caused by the hardness of the absorbent body 20. In order to do so, it is preferable to use particulate superabsorbent polymers 12 having a median particle diameter as the superabsorbent polymer. The median particle diameter is, for example, in the range of 50 μm to 600 μm or 100 μm to 500 μm.

In the absorbent body 20, the absorbent fibers and SAP may be in the form of a mixture of SAP particles in absorbent fibers, or an SAP sheet with SAP particles fixed between absorbent fibers. A carrier sheet may be provided under the absorbent body 20 to prevent leakage of SAP particles and stabilize the shape of the absorbent body 20. The base material of the carrier sheet may be any material that has hydrophilicity, and examples of the base material include hydrophilic nonwoven fabrics such as tissue, absorbent paper, and airlaid nonwoven fabrics. When multiple carrier sheets are provided, the base materials of the multiple carrier sheets may be the same or different.

(Back seat)
The back sheet 30 may be formed using a liquid-impermeable substrate that prevents the body fluid held by the absorbent 20 from wetting clothing, and examples of the substrate include a resin film, a composite sheet that is a laminate of a resin film and a nonwoven fabric, etc. The nonwoven fabric used in the composite sheet is not particularly limited in its manufacturing method, and examples thereof include composite nonwoven fabrics such as spunbond nonwoven fabric, meltblown nonwoven fabric, spunbond nonwoven fabric/meltblown nonwoven fabric laminate, spunbond nonwoven fabric/meltblown nonwoven fabric/spunbond nonwoven fabric laminate, and composite materials of two or more of these. Examples of the resin film include films of polyester, polyvinyl alcohol, polyethylene, polypropylene, etc., and composite films of polyethylene and polypropylene, etc.

The basis weight of the back sheet 30 is, for example, in the range of 15 g/ ^m2 to 60 g/ ^m2 in terms of strength and processability. In addition, in order to prevent stuffiness during wearing, it is preferable that the back sheet 30 has breathability. Examples of methods for imparting breathability to the back sheet 30 include a method of blending a filler into the resin film of the base material according to a known method, and a method of embossing the back sheet 30. Examples of the filler include calcium carbonate.

(3D gathers)
As shown in Figures 1 and 2, the pair of three-dimensional gathers 70 have a function of, for example, preventing lateral leakage of bodily fluids excreted by the wearer, and are provided to extend in the longitudinal direction near both ends in the width direction of the skin side of the top sheet 10. One end in the width direction of the sheet member constituting the three-dimensional gathers 70 is fixed near both ends in the width direction of the skin side of the back sheet 30, a middle part in the width direction is fixed near both ends in the width direction of the skin side of the top sheet 10, and the other end in the width direction is a free end 70a that is not fixed to the top sheet 10. By disposing an elastic stretchable member along the longitudinal direction near the free end 70a, the free end 70a has an upstanding property and can be deformed to fit the body shape of the wearer. Note that the absorbent articles 1, 2, and 3 include embodiments that do not include the three-dimensional gathers 70.

The fixing position of one widthwise end of the sheet member constituting the three-dimensional gathers 70 is not limited to this embodiment, and may be, for example, near both widthwise ends of the non-skin side of the back sheet 30, near both widthwise ends of a partially or completely joined body of the top sheet 10 and the back sheet 30 that contains the second sheet 40, the third sheet 50, the hydrophilic sheet 60, and the absorbent body 20 therein, near both widthwise ends of the skin side of the top sheet 10, etc.

The sheet member constituting the three-dimensional gathers 70 may be a water-repellent or liquid-impermeable nonwoven fabric formed of hydrophobic fibers, such as a spunbond nonwoven fabric, a meltblown nonwoven fabric, or a composite nonwoven fabric that is a spunbond nonwoven fabric/meltblown nonwoven fabric/spunbond nonwoven fabric laminate. The elastic stretch member may be, for example, a polyurethane thread, a belt-shaped polyurethane film, or a thread-shaped or belt-shaped natural rubber. The basis weight of the three-dimensional gathers 70 is, for example, in the range of 13 g/ ^m2 to 20 g/ ^m2 .

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

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

(Preparation of absorbent articles)
The absorbent body was a mixture of 7 g of fluff pulp as an absorbent base material and 6 g of SAP molded into a predetermined shape, the top sheet was an air-through nonwoven fabric (basis weight 25 g/ ^m2 ), the liquid-impermeable back sheet was a breathable polyethylene sheet (basis weight 32 g/ ^m2 ), the second sheet was an air-through nonwoven fabric (basis weight 30 g/ ^m2 , density 30 g/ ^cm3 ), the three-dimensional gathers were a composite nonwoven fabric (basis weight 15 g/ ^m2 ) which was a spunbond nonwoven fabric/meltblown nonwoven fabric/spunbond nonwoven fabric laminate, the hydrophilic sheet was tissue (basis weight 16 g/ ^m2 ), and the carrier sheet was spunbond nonwoven fabric (basis weight 15 g/ ^m2 ).

In addition, a soft polyurethane foam sheet (basis weight 40 g/ ^m2 , open cell, foaming ratio 12 times, compression stiffness LC: 0.8, compression recovery RC: 50%) was placed as the third sheet. At that time, a hot melt adhesive layer was formed between the second sheet and the third sheet with an adhesion area ratio of 30%, and the second sheet and the third sheet were bonded. In addition, as shown in FIG. 3(a), a 78 mm wide unbonded region was provided between the third sheet and the tissue, extending from one middle part in the longitudinal direction to the other middle part in the width direction center, and a hot melt adhesive layer was provided on both sides in the width direction to bond the third sheet and the tissue. In this way, the absorbent article of Example 1 was produced. The dimensions of the obtained absorbent article were 273 mm in the longitudinal direction and 105 mm in width, and the dimensions of the absorbent body were 220 mm in the longitudinal direction and 71 mm in width.

(Comparative Example 1) The absorbent article of Comparative Example 1 was prepared in the same manner as Example 1, except that a third sheet was not placed. (Comparative Example 2) The absorbent article of Comparative Example 2 was prepared in the same manner as Example 1, except that a second sheet was not placed. (Comparative Example 3) The absorbent article of Comparative Example 3 was prepared in the same manner as Example 1, except that the second sheet and the third sheet were bonded with an adhesive area ratio of 80%. (Comparative Example 4) The absorbent article of Comparative Example 4 was prepared in the same manner as Example 1, except that when the third sheet and the tissue were bonded with a hot melt adhesive, a 12 mm wide unbonded region was provided in the widthwise center.
The following evaluation tests were carried out on the absorbent articles obtained in Example 1 and Comparative Examples 1 to 4. The results are shown in Table 1.

(Skin feel of absorbent article surface)
Eight panelists evaluated the feel of the surface of the absorbent article to the touch. When 6 to 8 evaluators felt that the surface was soft, the rating was "○", when 3 to 5 evaluators felt that the surface was soft, the rating was "△", and when 1 or 2 evaluators or no evaluators felt that the surface was soft, the rating was "×".
(Leakability of absorbent articles)
Eight panelists evaluated the leak resistance of the absorbent article. After actually using one absorbent article, if six or more and eight or less evaluators judged that "side or back leakage did not occur," the rating was "○," if three or more and five or less evaluators judged that "side or back leakage did not occur," the rating was "△," and if one or two evaluators or no evaluators judged that "side or back leakage did not occur," the rating was "×."
(Absorption rate 3 times method)
A measuring jig weighing 755.6 g and having a hole with an inner diameter of 19 mm in the center of a cylinder with a base area of ^16.8 cm2 was placed on the center of the absorbent article in the longitudinal and width directions, and 40 ml of saline was dropped into the upper hole. The time from the point when the saline came into contact with the absorbent article to the point when the liquid was completely absorbed around the circumference of the central circle of the jig was used as the endpoint.
(Amount of liquid returned)
With the top sheet facing up, 120 ml of saline was poured towards the centre of the absorbent body and left for 10 minutes. After that, a filter paper (Advantec No. 2 filter paper, diameter 55 mm) whose weight had been measured in advance was placed on the area where the saline had been absorbed, and a 35 kgf/ ^cm2 weight was placed on top of it. After 30 seconds, the weight of the filter paper was measured and the difference in the weight of the filter paper was recorded as the amount of liquid return.

From Table 1, it can be seen that by having the specified configuration of this embodiment, an absorbent article can be obtained that has a good feel, prevents leakage, has a fast absorption rate, and has a small amount of liquid return, and has a good balance of various properties at a high level.

REFERENCE SIGNS LIST 1, 2, 3 Absorbent article 10 Top sheet 20 Absorbent body 30 Back sheet 40 Second sheet 50 Third sheet 60 Hydrophilic sheet 70 Three-dimensional gather 70a Free end 80 First hot melt adhesive layer 90 Unbonded region 91 Second hot melt adhesive layer

Claims (5)

An absorbent article comprising a liquid-permeable top sheet, a liquid-impermeable back sheet, a second sheet disposed on the non-skin side of the top sheet, and an absorbent body disposed between the second sheet and the back sheet,
The second sheet is a bulky nonwoven fabric having a density of 20 g/ ^cm3 or more and 40 g/cm3 or ^less ,
A third seat including a soft polyurethane foam arranged on a non-skin side of the second seat;
a hydrophilic sheet that covers the absorbent body and is disposed between the absorbent body and the third sheet;
a first hot melt adhesive layer provided on a skin side of the third sheet and interposed between the second sheet and the third sheet;
and a second hot melt adhesive layer provided on the non-skin side of the third sheet and interposed between the third sheet and the hydrophilic sheet. The first hot melt adhesive layer has an adhesive area ratio of 10% or more and 50% or less on the skin side of the third sheet.
The second hot melt adhesive layer has an unbonded region having a width of 15 mm or more and 90 mm or less , which extends in the longitudinal direction in the widthwise central portion of the third sheet and the hydrophilic sheet,
The unbonded region extends from one end to the other end in the longitudinal direction of the absorbent article,
The third sheet has a basis weight of 70 g/m ² or more and 300 g/m ² or less,
The compression stiffness LC of the third seat is 0.5 or more and 0.9 or less,
An absorbent article, characterized in that the compression recovery RC of the third sheet is 15% or more and 60% or less . The absorbent article according to claim 1, characterized in that the second sheet is an air-through nonwoven fabric. The absorbent article according to claim 1 or 2, characterized in that the hydrophilic sheet contains pulp. The absorbent article according to any one of claims 1 to 3, characterized in that the top sheet is an air-through nonwoven fabric. The absorbent article according to any one of claims 1 to 4, wherein the absorbent body contains fluff pulp and a superabsorbent polymer, and the weight ratio of the superabsorbent polymer to the total weight of the absorbent body is 40% by weight or more.