JP2023053339A - absorbent article - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an absorbent article capable of enhancing liquid diffusion property and absorption property of an absorbent core 10, relative to when using an adhesive material such as air laid.

SOLUTION: An absorbent core includes pulverized fibers, the pulverized fibers comprise: a broad leaf tree water holding fiber formed of a broad leaf tree; and a coniferous tree water holding fiber formed of a coniferous tree. On a center in at least a thickness direction of the absorbent core, the pulverized fibers entangle each other, thereby forming the absorbent core without using an adhesive material. The broad leaf tree water holding fiber is configured so that a total mass of the absorbent core on a skin side part when the absorbent core is divided into two parts in the thickness direction is greater than total mass of the absorbent core on a non skin side part, the coniferous tree water holding fiber is configured so that a total mass of the absorbent core on the non skin side part when the absorbent core is divided into two parts in the thickness direction is greater than the total mass of the absorbent core on the skin side.

SELECTED DRAWING: Figure 3

COPYRIGHT: (C)2023,JPO&INPIT

Description

The present invention relates to absorbent articles.

A sanitary napkin that absorbs excretions such as menstrual blood is known as an example of absorbent articles. Such sanitary napkins comprise an absorbent body (absorbent core), which contains water-retaining fibers. Softwood pulp fibers having a long inter-fiber distance are usually used as the water-retentive fibers. Patent Document 1 also discloses a water-retentive fiber that uses hardwood pulp fiber, which has a shorter interfiber distance than softwood pulp fiber.

Japanese Patent Publication No. 2004-538024

In an absorbent core using softwood pulp fibers, since the distance between fibers is long, there is a problem that rewet occurs in which excretory liquid once absorbed in the absorbent core returns to the wearer's skin.

Therefore, in the absorbent article of Patent Document 1, hardwood pulp fibers with a short interfiber distance are mixed with softwood pulp fibers, but are formed by the same manufacturing method (airlaid method) as non-woven fabrics, and are absorbent. Adhesive is applied to the core. In addition, such an adhesive may reduce the liquid absorbability and liquid diffusibility of the absorbent core.

The present invention has been made in view of the above problems, and its object is to improve the liquid diffusibility and liquid absorption of the absorbent core compared to the case where an adhesive such as airlaid is used. It is to enhance sexuality.

The main invention for achieving the above object is
having a longitudinal direction, a width direction, and a thickness direction perpendicular to each other;
An absorbent article comprising a liquid-permeable topsheet, a liquid-impermeable backsheet, and an absorbent core provided between the topsheet and the backsheet,
The absorbent core has pulverized fibers,
The pulverized fibers contain hardwood water-retaining fibers made from hardwoods and softwood water-retaining fibers made from softwoods,
At least at the center in the thickness direction of the absorbent core, the pulverized fibers are entangled with each other to form the absorbent core without using an adhesive,
In the hardwood water-retentive fiber, the total weight of the skin-side portion of the absorbent core when divided into two equal parts in the thickness direction is greater than the total weight of the non-skin-side portion of the absorbent core,
The soft water-retentive fiber is characterized in that the total weight of the non-skin side portion of the absorbent core when divided into two equal parts in the thickness direction is larger than the total weight of the skin side portion of the absorbent core. It is an absorbent article.

Other features of the present invention will become apparent from the description of the specification and accompanying drawings.

According to the present invention, it is possible to improve the liquid diffusibility and liquid absorbency of the absorbent core compared to the case of using an adhesive such as airlaid.

It is the schematic plan view which looked at the napkin 1 from the skin side of the thickness direction. FIG. 2 is a schematic cross-sectional view taken along line AA in FIG. 1; 4A to 4C are diagrams for explaining a method of manufacturing the absorbent body 10. FIG. FIG. 4 is an explanatory diagram showing how the fibers of the second sheet 4 and the fibers of the absorbent body 10 are entangled. It is a figure explaining the difference in the average inter-fiber distance of hardwood pulp and softwood pulp. FIG. 1 is a diagram (Table 1) showing an average inter-fiber distance Dp of fibers. FIG. 2 is a diagram showing fiber length distributions of hardwood pulp fibers and softwood pulp fibers. It is the schematic plan view which looked at the napkin 1 from the non-skin side of the thickness direction. FIG. 2 is a diagram showing fiber width distributions of hardwood pulp and softwood pulp.

At least the following matters will become apparent from the descriptions of this specification and the accompanying drawings.

A liquid-permeable top sheet, a liquid-impermeable back sheet, and an absorbent provided between the top sheet and the back sheet, having longitudinal directions, width directions, and thickness directions orthogonal to each other. and a core, wherein the absorbent core has pulverized fibers, and the pulverized fibers include hardwood water-retaining fibers made of hardwood and soft water-retaining fibers made of softwood. The absorbent core is formed without using an adhesive by intertwining the pulverized fibers at least in the center in the thickness direction of the absorbent core. An absorbent article characterized by:

According to such an absorbent article, the liquid diffusibility and liquid absorbency of the absorbent core can be improved as compared with the case where an adhesive such as airlaid is used.

In this absorbent article, the hardwood water-retaining fiber is such that the total weight of the skin-side portion of the absorbent core when halved in the thickness direction is the total weight of the non-skin-side portion of the absorbent core. The total weight of the non-skin side portion of the absorbent core when the soft water-retentive fibers are divided into two equal parts in the thickness direction is greater than the total weight of the skin side portion of the absorbent core. is desirable.

According to such an absorbent article, it is possible to provide an absorbent article that is fitted to the body, has improved diffusibility of menstrual blood, etc., and is suppressed from losing its shape.

In such an absorbent article, the average interfiber distance of the pulverized fibers on the skin side of the absorbent core is equal to the average interfiber distance of the pulverized fibers on the non-skin side of the absorbent core. It is desirable to be smaller than the distance.

According to such an absorbent article, it is possible to suppress the diffusion of menstrual blood and the like in the non-skin side portion where the average inter-fiber distance is large, and it is possible to suppress the leakage of menstrual blood and the like.

In such an absorbent article, it is desirable that the absorbent article is provided with an elastic member that expands and contracts in the longitudinal direction.

According to such an absorbent article, the elasticity of the elastic member causes the skin-side surface, which contains a large amount of soft hardwood pulp, to move in conjunction with the movement of the body, so that the fit can be further improved.

In this absorbent article, the hardwood water-retaining fiber is such that the total weight of the non-skin side portion of the absorbent core when bisected in the thickness direction is the total weight of the skin side portion of the absorbent core. and the total weight of the soft water-retentive fiber on the skin side of the absorbent core when divided into two equal parts in the thickness direction is greater than the total weight of the non-skin side of the absorbent core. is desirable.

According to such an absorbent article, it is possible to maximize the use of the absorbent body by increasing the liquid diffusion area on the non-skin side while suppressing a decrease in the liquid absorption rate on the skin side.

In such an absorbent article, the average interfiber distance of the pulverized fibers on the skin side of the absorbent core is equal to the average interfiber distance of the pulverized fibers on the non-skin side of the absorbent core. Greater than the distance is desirable.

According to such an absorbent article, it is possible to suppress a decrease in the liquid absorption rate in the skin side portion, and to quickly move menstrual blood and the like to the non-skin side with good liquid diffusibility.

In this absorbent article, the total weight of the hardwood water-retentive fibers is the same when the front side and the back side are compared when the longitudinal direction is bisected, and when the width direction is bisected. The difference is 10 %, and the total weight of the softwood water-retentive fibers is the left side when the front side and the back side are compared when the longitudinal direction is bisected, and the width direction is bisected. and the right side, and when comparing the skin side and the non-skin side when the thickness direction is divided into two equal parts, the difference is within 10% It is desirable to have

According to such an absorbent article, it is possible to improve fit to the body and diffusibility of menstrual blood and other liquids while suppressing deformation as a whole.

In such an absorbent article, it is desirable that the total weight of the hardwood water-retaining fibers in the absorbent core is greater than the total weight of the softwood water-retaining fibers in the absorbent core.

According to such an absorbent article, the content of the hardwood pulp is more, so that the liquid diffusibility and the rewet property can be improved as compared with the case where the hardwood pulp is less.

Such an absorbent article, wherein the total weight of said softwood water-retaining fibers in said absorbent core is greater than the total weight of said hardwood water-retaining fibers in said absorbent core.

According to such an absorbent article, since there is more softwood pulp, it is possible to suppress the deformation compared to when there is less softwood pulp.

In this absorbent article, the absorbent core is formed by laminating the pulverized fibers, and the absorbent core is such that the weight of the hardwood water-retaining fibers is greater than the weight of the softwood water-retaining fibers. and a softwood layer in which the weight of the softwood water-retentive fibers is heavier than the weight of the hardwood water-retainable fibers, and the hardwood layer is provided closer to the skin than the softwood layer, When viewed in the thickness direction, it is desirable that the outer edge of the broadleaf tree layer is located inside the outer edge of the softwood layer.

According to such an absorbent article, it is possible to suppress deterioration of liquid diffusibility in the outer peripheral region of the absorbent core while further suppressing deformation, and it is possible to suppress external leakage of excreted liquid.

In this absorbent article, the absorbent article has a skin-side sheet made of fibers, the skin-side sheet is provided adjacent to the skin side of the absorbent core, and is made of the broadleaf tree. At least part of the water-retaining fibers protrudes from the skin-side surface of the absorbent core and extends to the inside of the skin-side sheet. It is desirable that the portion is in contact with the fibers of the adjacent skin side sheet.

According to such an absorbent article, menstrual blood and the like can easily enter the absorbent core along the hardwood water-retentive fibers, and the liquid absorption rate can be improved.

In this absorbent article, the absorbent core has a synthetic fiber, and the synthetic fiber is more dense than the non-skin side portion of the absorbent core when divided into two equal parts in the thickness direction. It is preferred that the synthetic fibers are fused to each other in the skin-side portion of the absorbent core.

According to such an absorbent article, since the synthetic fibers are connected and fused to each other, the liquid diffusibility is improved at the side of the skin, and the rigidity is improved, thereby suppressing deformation.

In such an absorbent article, the absorbent article includes a cover sheet, the cover sheet is joined to the absorbent core adjacent to the non-skin side of the absorbent core, and the back is attached to the absorbent core. The sheet is joined to the cover sheet adjacent to the non-skin side of the cover sheet, and the non-skin side of the back sheet is provided with a non-slip stopper extending in a first direction in a second direction perpendicular to the first direction. It is preferable that a plurality of the anti-slip stoppers are provided at intervals in two directions, and that the minimum value of the intervals in the second direction of the anti-slippage is longer than the average fiber length of the water-retentive fibers made of the broad-leaved tree.

According to such an absorbent article, since the absorbent core can be easily bent between the anti-slip portions, the absorbent article can be easily interlocked with the movement of the body and the fitting property can be improved.

In this absorbent article, the average fiber width of the hardwood water-retaining fibers is 15 μm or less, and the number of the hardwood water-retaining fibers contained per unit area of the absorbent core is 300 fibers/mm2 or more, 2500 fibers/mm2 or more. It is desirable to have a superabsorbent polymer between a plurality of the hardwood water-retentive fibers and less than fibers/mm2.

According to such an absorbent article, since the excreted liquid contained in the hardwood pulp is easily drawn into the superabsorbent polymer between the hardwood pulps, liquid return can be reduced even when the excreted liquid is absorbed a plurality of times. can be done.

In such an absorbent article, it is desirable that the standard deviation of the fiber length of the hardwood water-retaining fibers is 0.27 or less, and the standard deviation of the fiber width of the hardwood water-retaining fibers is 7.55 or less.

According to such an absorbent article, since it is easy to maintain a uniform fiber density in the absorbent body, it is easy to spread concentrically with little unevenness in the planar direction.

In this absorbent article, the value obtained by adding the standard deviation of the fiber length of the hardwood water-retaining fibers to the average fiber length of the hardwood water-retaining fibers is twice the average fiber length of the hardwood water-retaining fibers. The value obtained by subtracting the standard deviation of the fiber length of the hardwood water-retaining fiber from the average fiber length of the hardwood water-retaining fiber is less than 1/2 of the average fiber length of the hardwood water-retaining fiber should be large.

According to such an absorbent article, since it is easy to maintain a uniform fiber density in the absorbent body, it is easy to spread concentrically with little unevenness in the planar direction.

In this absorbent article, the absorbent core includes a plurality of thermoplastic fibers and has a compressing portion that integrally compresses the absorbent core in the thickness direction, and in the compressing portion , the thermoplastic fibers are preferably fused together.

According to such an absorbent article, even when the wearer makes a large body movement, it is possible to easily prevent the absorber 10 from losing its shape or deteriorating its water absorbency.

===First embodiment===
<<Basic composition of a sanitary napkin>>
A sanitary napkin 1 (hereinafter simply referred to as napkin 1) will be described as an example of an absorbent article according to the present embodiment. In the following description, a sanitary napkin will be described as an example of an absorbent article, but the absorbent article of the present embodiment also includes so-called vaginal discharge sheets (for example, panty liners) and light incontinence pads. It is not limited to sanitary napkins.

FIG. 1 is a schematic plan view of the napkin 1 viewed from the skin side in the thickness direction. FIG. 2 is a schematic cross-sectional view taken along line AA in FIG. Also, in the following description, each direction is defined as shown in FIGS. That is, the "longitudinal direction" along the product longitudinal direction of the napkin 1, the "width direction" perpendicular to the longitudinal direction along the product transverse direction of the napkin 1, and the "thickness Define "direction". Among the longitudinal directions, the direction that corresponds to the abdomen of the wearer when using the napkin 1 is defined as the "front side", and the direction that corresponds to the back of the wearer is defined as the "rear side". In the thickness direction, the side that comes into contact with the wearer's skin when the napkin 1 is worn is defined as the "skin side (upper side)", and the opposite side is defined as the "non-skin side (lower side)".

The napkin 1 is a sheet-like member having a vertically long shape in plan view, and includes a pair of side sheets 2, a top sheet 3, a second sheet 4, an absorbent body 10, a cover sheet 6, and a back sheet 5 in the thickness direction. are laminated in order from the skin side to the non-skin side (see FIG. 2). Each of these members is bonded to members adjacent in the thickness direction with an adhesive such as a hot melt adhesive (HMA). Examples of the application pattern of the adhesive include an Ω pattern, a spiral pattern, a stripe pattern, and the like.

Further, the napkin 1 has a napkin main body 20 provided with the absorbent body 10 and a pair of wing parts 30 extending from the central region in the longitudinal direction of the napkin main body 20 to both sides in the width direction. The central region in the longitudinal direction where the wing portions 30 are provided is the region that comes into contact with the wearer's excretory opening (crotch portion) when the napkin 1 is in use.

The top sheet 3 is a member that comes into contact with the wearer's skin when the napkin 1 is in use. For this reason, an appropriate liquid-permeable and flexible sheet such as an air-through nonwoven fabric is used for the top sheet 3 .

The second sheet 4 (corresponding to the skin side sheet) is a sheet made of liquid-permeable fibers, and the same air-through nonwoven fabric as the top sheet 3 can be exemplified. The second sheet 4 is provided on the skin side of the absorbent body 10 (adjacent to the skin side), and plays a role of preventing backflow of excrement such as menstrual blood, improving diffusion of excrement, and improving cushioning properties. . However, the napkin 1 may not have the second sheet 4 (for example, the top sheet 3 may be substituted).

The cover sheet 6 may be a liquid-permeable sheet or a liquid-impermeable sheet, and examples thereof include tissue paper and SMS (spunbond/meltblown/spunbond) nonwoven fabric. A cover sheet 6 is provided between the absorbent body 10 and the back sheet 5 . That is, the napkin 1 has a cover sheet 6, the cover sheet 6 is joined to the absorbent body 10 adjacent to the non-skin side of the absorbent body 10, and the back sheet 5 is the 6 non-skin side of the cover sheet. It is joined to the cover sheet 6 adjacent to the side. However, the napkin 1 may not have the cover sheet 6 (for example, the back sheet 5 may be substituted).

The back sheet 5 suppresses the liquid that permeates the top sheet 3 and is absorbed by the absorbent body 10 during use of the napkin 1 from seeping out to the clothing side (non-skin side) such as underwear. As the back sheet 5, an appropriate liquid-impermeable flexible sheet such as a polyethylene (PE) resin film is used. The planar size of the top sheet 3 and the back sheet 5 is larger than that of the absorbent body 10 .

Further, the back sheet 5 is provided with a thread rubber 5a (corresponding to an elastic member) that expands and contracts in the longitudinal direction. The elastic thread 5a expands and contracts to further improve fit to the body (details will be described later). The elastic member is not limited to the rubber thread 5a, and for example, a stretchable sheet may be provided.

The side sheet 2 may be a liquid-permeable sheet or a liquid-impermeable sheet, and examples thereof include an SMS nonwoven fabric and the same air-through nonwoven fabric as the top sheet 3 .

Then, as shown in FIGS. 1 and 2, the side sheet 2 and the top sheet 3 and the back sheet 5 are joined together at their outer peripheral edges by adhesion or welding, so that an absorbent material is absorbed between these sheets. A body 10 is held. The pair of side sheets 2 extend outward in the width direction from both sides of the top sheet 3 in the width direction, and form a pair of wing portions 30 together with the back sheet 5 .

On the non-skin side of the napkin body 20 in the thickness direction (that is, the non-skin side of the back sheet 5), an appropriate adhesive (for example, hot-melt adhesive) is applied to a plurality of belt-like regions along the longitudinal direction. Adhesive portion 21 for main body portion (corresponding to anti-slippage) is provided (see FIGS. 2 and 8). That is, on the non-skin side of the backsheet 5, a plurality of anti-slippages extending in the longitudinal direction are provided at intervals in the width direction. When the napkin 1 is used, the main body adhesive part 21 is attached to the skin side of underwear or the like, thereby fixing the napkin 1 to the underwear or the like.

Similarly, the non-skin side of each wing 30 in the thickness direction (that is, the non-skin side of the backsheet 5) is provided with a wing adhesive portion 31 (see FIG. 2). When the napkin 1 is used, the wing portions 30 are folded toward the non-skin side, and the adhesive portions 31 for the wing portions are adhered to the non-skin side of underwear or the like, thereby fixing the napkin 1 to the underwear or the like.

The absorber 10 (corresponding to an absorbent core) is a vertically long member that is elongated along the longitudinal direction, and absorbs liquid (excretion) such as menstrual blood and retains it inside. Details of the absorbent body 10 will be described later. The second sheet 4, the absorbent body 10, and the cover sheet 6 have the same planar shape and are laminated in the thickness direction. In this embodiment, these members are joined to each other by a hot melt adhesive (HMA), but they do not have to be joined.

Moreover, the napkin 1 is provided with a plurality of pressing portions 40 (recesses). The pressed portion 40 is a portion where the top sheet 3, the second sheet 4, and the absorbent body 10 are integrally pressed and recessed from the skin side toward the non-skin side in the thickness direction, and the density of the absorbent body 10 is the same. It is a site with a higher density than the surrounding area. That is, the top sheet 3, the second sheet 4, and the absorbent body 10 have uneven portions on the skin side surface. As a result, menstrual blood or the like flows from the convex portion to the concave portion on the skin side surface of the member, and the moving speed of the menstrual blood or the like can be improved.

<<About Absorber 10>>
The absorbent body 10 has water-retentive fibers that absorb liquid, and is formed in a vertically long shape in a plan view. As the water-retaining fibers according to the present embodiment, wood of softwood pulp fibers (hereinafter also referred to as softwood pulp, corresponding to softwood water-retaining fibers) and hardwood pulp fibers (hereinafter also referred to as hardwood pulp, corresponding to hardwood water-retaining fibers) Pulp is ground and used. Then, the absorbent body 10 is formed by entangling pulverized fibers (water-retentive fibers) without using an adhesive.

Softwood pulp and hardwood pulp include, for example, wood pulp obtained by pulverizing southern yellow pine for softwood pulp, and wood pulp obtained by pulverizing eucalyptus for hardwood pulp.

Moreover, the absorbent body 10 may have liquid-absorbent particles such as a superabsorbent polymer (so-called SAP).

As a method of manufacturing the absorbent body 10, a method of accumulating pulverized pulp, superabsorbent polymer, or the like is known.

3A and 3B are diagrams for explaining a method for manufacturing the absorbent body 10. FIG. Here, a case of manufacturing an absorbent body 10 containing water-retentive fibers (softwood pulp and hardwood pulp) and superabsorbent polymer (SAP) will be described.

The rotary drum 70 is a hollow cylindrical drum, and a plurality of recesses 71 are formed at a predetermined pitch on the peripheral surface as a mold for filling the absorbent material. When the rotary drum 70 rotates and the concave portion 71 enters the material supply section 80 , the absorber material supplied from the material supply section 80 accumulates (accumulates) in the concave portion 71 due to the suction of the suction section 72 .

A material supply unit 80 with a hood 80a is formed to cover the upper part of the rotating drum 70, and the material supply unit 80 supplies pulverized pulp (pulverized fibers) obtained by pulverizing a pulp sheet with a pulverizer (not shown). is supplied to the recess 71 by pneumatic conveyance. At this time, the pulverized pulp is supplied so as to be entangled with each other (then, the pulverized pulp is firmly entangled by the suction of the suction part 72). The material supply unit 80 also includes a particle supply unit 81 that supplies superabsorbent polymer particles, and supplies the superabsorbent polymer particles to the concave portions 71 . The water-retaining fibers and the superabsorbent polymer particles are deposited in the recesses 71 in a mixed state to form the absorbent body 10 in the recesses 71 .

Further rotation of the rotary drum 70 causes the recess 71 accommodating the absorbent 10 to reach the bottom of the drum, causing the absorbent 10 to come off the recess 71 and remove the substrate (such as the cover sheet 6) conveyed by the conveyor. It will be placed on top and handed over to the next process.

In the subsequent steps, for example, a hot-melt adhesive (HMA) is applied to the skin-side surface of the absorbent body 10 to join the second sheet 4 and the absorbent body 10, and the second sheet 4 is attached to the absorbent body 10. be pushed. Then, the absorbent body 10 has an adhesive on the skin-side surface layer (the surface and the part where the adhesive penetrates into the absorbent body 10). It does not reach the center in the thickness direction of 10 .

The absorber described in Patent Document 1 uses a sheet (air-laid) formed by a manufacturing method (air-laid method) similar to that for non-woven fabrics, such as pulp fibers, thermoplastic resin fibers, and powders. Adhesive is applied to the airlaid (that is, the adhesive is present throughout the absorbent body). becomes higher, and the liquid diffusibility and liquid absorption of the excreted liquid are reduced. That is, when the absorbent body 10 is manufactured using the manufacturing method shown in FIG. An absorbent body 10 with high absorbency can be manufactured.

In other words, since the adhesive in the absorbent lowers the liquid diffusibility and liquid absorbability of the excreted liquid, forming the absorbent 10 without using an adhesive reduces the effect of using an adhesive such as airlaid. In comparison, liquid diffusibility and liquid absorption can be enhanced at least at the center in the thickness direction of the absorbent body 10 . In addition, the absorbent body 10 containing hardwood pulp is softer and more absorbent than the absorbent body 10 containing only softwood pulp, and the absorbent body 10 containing softwood pulp is more flexible than the absorbent body 10 containing only hardwood pulp. is resistant to wrinkling and crumbling. In other words, by including both the hardwood pulp and the softwood pulp in the absorbent body 10, the softwood pulp serves as a skeleton, and the hardwood pulp is filled in between, so that the napkin is soft, highly absorbent, and resistant to twisting and crumbling. 1 can be provided.

That is, the absorbent body 10 has pulverized fibers, and the pulverized fibers include hardwood pulp made of hardwood and softwood pulp made of softwood. In the center, the pulverized fibers are entangled with each other to form the absorbent body 10 without the use of adhesive.

Further, by pressing the second sheet 4 and the absorbent body 10 in the thickness direction, the water-retentive fibers of the absorbent body 10 are entangled with the fibers of the second sheet 4 . FIG. 4 is an explanatory view showing how the fibers of the second sheet 4 and the fibers of the absorbent body 10 are entangled. As will be described later, since hardwood pulp is thin, entanglement occurs between fibers, but softwood pulp is thick, so it is difficult for fibers to enter and such entanglement does not easily occur (or does not occur). That is, the water-retentive fibers in FIG. 4 represent hardwood pulp.

Looking at FIG. 4, inside the second sheet 4, the fibers 4f of the second sheet 4 (indicated by white lines in the enlarged view) are in contact with the water-retentive broadleaf fibers 10f of the absorbent body 10 (indicated by black lines in the enlarged view). are doing. In other words, at least part of the hardwood water-retaining fibers 10f protrude from the skin-side surface of the absorbent body 10 and extend to the inside of the second sheet 4. A part is in contact with the fibers of the second sheet 4 .

This contact between the fibers makes it easier for the excreted liquid to enter the interior of the absorbent body 10 from the fibers 4f of the second sheet 4 through the hardwood water-retaining fibers 10f, thereby increasing the liquid absorption speed. In addition, since the water-retentive fibers are caught on the skin-side sheet, it is possible to suppress the absorber 10 from being twisted and to prevent the absorber 10 from losing its shape.

Moreover, the thickness of the absorbent body 10 is desirably 2 mm or more and 10 mm or less. If the thickness of the absorbent body 10 is less than 2 mm, it is too thin and may be twisted.

Further, the fiber number density of hardwood pulp is higher than that of softwood pulp because it is finer and the distance between fibers is shorter than that of softwood pulp. The fiber number density corresponds to the average number of fibers per unit area, and is a value obtained by calculating the number of fibers contained per unit area in the case of a close-packed structure by dividing the fiber thickness + the average distance between fibers. . According to this trial calculation, the fiber number density of hardwood pulp is 1182.2 fibers/mm2, which is approximately six times the fiber number density of softwood pulp (200.3 fibers/mm2). Therefore, the use of hardwood pulp allows higher density than the use of softwood pulp.

The fiber number density is desirably 300/mm2 or more and less than 2500/mm2.
If the fiber number density is less than 300 fibers/mm2, the absorbent body 10 becomes faint and twists during use, resulting in a reduced absorbent body area and a tendency to leak. If the fiber number density is 2500 fibers/mm2 or more, the absorbent body 10 will be finished too hard, and discomfort during use will increase. If the fiber number density is 300 fibers/mm2 or more and less than 2500 fibers/mm2, the capillary effect can be enhanced, thinning and softening can be achieved, and absorbency can be enhanced.

Further, it is preferable that the fiber number density of the hardwood pulp is higher than that of the softwood pulp. By doing so, it is possible to increase the capillary effect while maintaining the softness of the absorbent body 10 .

<<Combination of hardwood pulp and softwood pulp>>
Next, the blending of hardwood pulp and softwood pulp in absorbent body 10 will be described. In the present embodiment, the content of hardwood pulp is greater than that of softwood pulp on the skin side of absorbent body 10, and the content of softwood pulp is greater than that of hardwood pulp on the non-skin side of absorbent body 10 (by weight. The weight is, for example, measured with an electronic balance HF-300 manufactured by Kensei Kogyo Co., Ltd.). That is, in hardwood pulp, the total weight of the skin side portion of the absorbent body 10 when divided into two equal parts in the thickness direction is greater than the total weight of the non-skin side portion of the absorbent body 10. The total weight of the non-skin side portion of the absorbent body 10 when divided into two equal parts is greater than the total weight of the skin side portion of the absorbent body 10 .

Such adjustment of the composition in the thickness direction can be realized, for example, by manufacturing the absorbent body 10 as follows. First, a hardwood pulp roll and a softwood pulp roll are prepared. Then, each pulp roll is pulverized by a saw mill or the like, and after the pulverization, the pattern plate is manufactured by adjusting the mixing ratio of each. In addition, it is preferable to use two saw mills, but this is an example, and each pulp is pulverized by one saw mill, and the hardwood pulp and the softwood pulp are mixed at the stage between pulverization and lamination. You can change the ratio of Then, the hardwood pulp is more than the softwood pulp on the skin side of the absorbent body 10 (bottom side of the recessed portion 71), and the softwood pulp is more than the hardwood pulp on the non-skin side of the absorbent body 10 (opening side of the recessed portion 71). can do.

According to such a napkin 1, since the hardwood pulp is more on the skin side, the napkin 1 is easy to bend and fits the body softly, and the diffusion of liquid such as menstrual blood is improved, and the softwood pulp is on the non-skin side. Since there are many in the part, the skeleton is formed in the non-skin side part, and the loss of shape is suppressed. In other words, it is possible to provide the napkin 1 that fits the body, improves diffusion of menstrual blood, etc., and suppresses deformation. In addition, since the absorbent core is made of hardwood pulp, it has the effect of confining menstrual blood and the like that has been drawn in once, and the rewetting property can be enhanced (return of liquid can be reduced).

Further, in the present embodiment, the total weight of hardwood pulp in absorbent body 10 is greater than the total weight of softwood pulp in absorbent body 10 . Then, since the hardwood pulp is more than the softwood pulp, the average inter-fiber distance (described later) can be shortened compared to the case where the hardwood pulp is less than the softwood pulp. When the average inter-fiber distance is short, capillary action is likely to occur, so liquid diffusion can be improved and liquid return (rewet) can be reduced.

Further, as described above, the back sheet 5 is provided with the thread rubber 5a (elastic member) that stretches and contracts in the longitudinal direction. Then, as in the present embodiment, the absorbent body 10 containing a large amount of hardwood pulp on the skin side is stretched by the rubber thread 5a, so that the absorbent body 10 is deformed along the curve of the body. (Coniferous pulp is hard and hard to deform, while hardwood pulp is soft and easy to deform, so if there is a lot of hardwood pulp on the skin side, it will be easier to follow the curve of the body).

<<Average inter-fiber distance evaluation>>
Next, the average inter-fiber distance of hardwood pulp and softwood pulp was evaluated by the following method.

Samples of 100% hardwood pulp, 100% softwood pulp, and 50% hardwood pulp + 50% softwood pulp were prepared as samples, and the 3D image connection function of the microscope (KEYENCE VHX-2000, lens VH-Z20W aperture open) was used. is used to obtain a magnified image that is in focus from the surface of the sample to a depth of 100 μm (for example, a 500x image for broad-leaved trees and a 100x image for coniferous trees), and based on the magnified image, fibers that are in focus extracted the outside of the Let the surface formed there be a fiber space. The diameter of the maximum inscribed circle of the fiber space was defined as the fiber space distance, and the average value for 100 fiber spaces was defined as the average interfiber distance (Dp).

FIG. 5 is a diagram for explaining the difference in the average interfiber distance between hardwood pulp and softwood pulp. The left figure shows the average interfiber distance in hardwood pulp, and the right figure shows the average interfiber distance in softwood pulp. . As shown in FIG. 5, the diameter of the maximum inscribed circle in each fiber space is the inter-fiber distance, so softwood pulp has a long average inter-fiber distance and hardwood pulp has a short average inter-fiber distance.

FIG. 6 is a diagram showing the average fiber-to-fiber distance Dp of fibers. As shown in FIG. 6, the 100% hardwood pulp has a smaller average inter-fiber distance Dp than the 100% softwood pulp. And 50% hardwood pulp + 50% softwood pulp is greater than 100% hardwood pulp and less than 100% softwood pulp. That is, when the composition of the hardwood pulp and the softwood pulp changes, the average inter-fiber distance Dp of the fibers also changes.

In the absorbent body 10, the hardwood pulp is more than the softwood pulp in the skin side portion, and the softwood pulp is more than the hardwood pulp in the non-skin side portion. That is, the average inter-fiber distance Dp of the pulverized fibers (water-retaining fibers) on the skin side of the absorbent body 10 is the average inter-fiber distance Dp of the pulverized fibers (water-retaining fibers) on the non-skin side of the absorbent body 10. smaller than Dp.

Then, since the average interfiber distance Dp is smaller on the skin side than on the non-skin side, the movement of menstrual blood, etc. to the non-skin side can be reduced by the capillary effect while diffusing menstrual blood, etc. on the skin side. can be done. That is, it is possible to suppress the diffusion of menstrual blood and the like in the non-skin side portion where the average inter-fiber distance Dp is large, and it is possible to suppress the leakage of menstrual blood and the like.

Evaluation of the average inter-fiber distance Dp is, for example, in the skin side portion, by peeling off the use side sheet (second sheet 4) of the absorbent body 10 and exposing the exposed surface of the absorbent body 10 using the microscope described above. to measure the average interfiber distance Dp, and on the non-skin side, peel off the non-use side sheet (cover sheet 6) of the absorbent body 10 and expose the exposed surface of the absorbent body 10 using the microscope described above. It is possible by measuring the average fiber-to-fiber distance Dp.

<<About the average fiber length of the water-retentive fiber>>
Next, the relationship between the average fiber length of the water-retentive fibers and the body adhesive portion 21 will be described. FIG. 7 is a diagram showing the fiber length distribution of hardwood pulp fibers and softwood pulp fibers. The horizontal axis indicates fiber length (mm), and the vertical axis indicates frequency (%). As shown in the figure, the softwood pulp has an average fiber length of 2.5 mm and a wide distribution of fiber lengths (including fibers of 3 mm or more; standard deviation is 1.6). On the other hand, the average fiber length of hardwood pulp is 0.79 mm, and the distribution width of fiber length is narrow (standard deviation is 0.27).

The average fiber length means the length-weighted average fiber length measured by the center fiber length (Cont). Length-weighted average fiber length is measured as the L(l) value by kajaani FiberLab fiber properties (off-line) from metso automation. This is also the method recommended in JIS P 8226-2 (pulp - fiber length measurement method by mechanical automatic analysis method, conforming to non-polarization method). Also, as described in the JIS evaluation method, the average fiber length and the fiber width described later are the results of measurements excluding lumps of fibers.

FIG. 8 is a schematic plan view of the napkin 1 viewed from the non-skin side in the thickness direction. As shown in FIG. 8 , on the non-skin side of the back sheet 5 , the main body adhesive portion 21 extending in the longitudinal direction (corresponding to the first direction) extends in the width direction (first direction) orthogonal to the longitudinal direction (first direction). The minimum value of the interval 21g in the width direction (second direction) is longer than the average fiber length of water-retentive fibers made of hardwood.

Therefore, when receiving a deforming force from the underwear, the amount of water-retentive fibers straddling the installation portion and the non-installation portion of the body adhesive portion 21 can be reduced, and the absorbent body 10 is placed between the body adhesive portions 21. , the napkin 1 is easily linked with the movement of the body, and the fitting property is improved.

Note that the main body adhesive portion 21 shown in FIG. 8 extends in the longitudinal direction and is provided in plurality at intervals of 21g in the width direction. They may be spaced apart in the longitudinal direction.

<<About the average fiber width of the water-retentive fiber>>
Next, the average fiber width of water-retentive fibers will be described. The measurement is performed in the same manner as the average fiber length described above, and is measured as FiberWidth.

FIG. 9 is a diagram showing the average fiber width distribution of hardwood pulp and softwood pulp. The horizontal axis indicates the fiber width (μm), and the vertical axis indicates the frequency (%). As shown in FIG. 9, the average fiber width of the softwood pulp is about 30 μmm (upper figure), and the distribution width of the fiber width is wide (standard deviation is 11.9). On the other hand, the average fiber width of hardwood pulp is about 15 μm (lower figure), and the width of the fiber width distribution is narrow (standard deviation is 7.55). In the napkin 1 of the present embodiment, since hardwood pulp is used for the absorbent body 10, the average fiber width of the water-retentive fibers is shorter than when only softwood pulp is used.

The hardwood pulp has an average fiber width of 15 μm or less, a fiber number density of 300 fibers/mm2 or more and less than 2500 fibers/mm2 as described above, and has a superabsorbent polymer between the hardwood pulp. desirable. As a result, the hardwood pulp, which is characterized by the fact that the fibers are less likely to be entangled and has a short fiber width, is densely packed, so that the fibers easily contain the excreted liquid, and the excreted liquid contained in the hardwood pulp is between the hardwood pulps. Since it is likely to be drawn into the superabsorbent polymer, liquid return can be reduced even when excreted liquid is absorbed multiple times.

Looking at the width of the distribution, hardwood pulp has a narrower distribution of fiber length and width than softwood pulp. That is, the standard deviation of the fiber length of the hardwood pulp is 0.27 or less, and the standard deviation of the fiber width of the hardwood pulp is 7.55 or less. Furthermore, the value obtained by adding the standard deviation of the fiber length of the hardwood pulp to the average fiber length of the hardwood pulp (0.79 + 0.27 = 1.06) is twice the average fiber length of the hardwood pulp (1.58) The value obtained by subtracting the standard deviation of the fiber length of hardwood pulp from the average fiber length of hardwood pulp (0.79-0.27 = 0.52) is 1/2 of the average fiber length of hardwood pulp greater than (0.395).

When the distribution width is narrow and the standard deviation is small, it is easy to maintain a uniform fiber density in the absorbent body, so that the fibers tend to diffuse concentrically with little deviation in the planar direction.

Looking at the average fiber length and average fiber width of the water-retaining fibers, softwood pulp is thicker and longer than hardwood pulp, so the pulps tend to entangle each other and form a firm skeleton. do. On the other hand, since the hardwood pulp is thin and short, it is difficult for the pulps to entangle with each other, but it is easy for them to enter between the softwood pulps. It is possible to provide the napkin 1 with high liquid diffusibility and rewetability.

=== Second Embodiment ===
Next, with regard to the second embodiment, the description of the same points as those of the above-described first embodiment is omitted, and the points of difference from the first embodiment will be described.

The difference between the second embodiment and the first embodiment is the blending of hardwood pulp and softwood pulp in the absorber. In many cases, the non-skin side of the absorber contains more hardwood pulp than softwood pulp. That is, the total weight of the non-skin side of the absorbent body when divided into two equal parts in the thickness direction of the hardwood pulp is greater than the total weight of the skin side of the absorbent body, and the softwood pulp is 2nd class in the thickness direction. The total weight of the skin side portion of the absorbent body when divided is greater than the total weight of the non-skin side portion of the absorbent body.

Then, since the softwood pulp is more in the skin side, the strike-through property (liquid permeability and high strike-through property makes it difficult for the liquid absorption rate to decrease) is improved, and the hardwood pulp is more in the non-skin side. Therefore, the liquid drawing property and the liquid diffusing property are improved. That is, by increasing the liquid diffusion area on the non-skin side while suppressing the decrease in the liquid absorption rate on the skin side, the absorber can be utilized to the maximum. In addition, since the absorber is provided with hardwood pulp, there is an effect of confining menstrual blood and the like once drawn in, and rewetability can be enhanced.

As for the average inter-fiber distance Dp, as described above, since the average inter-fiber distance Dp differs between the hardwood pulp and the softwood pulp (see FIGS. 5 and 6), the fiber The average fiber-to-fiber distance Dp also changes. In the absorbent body according to the second embodiment, the softwood pulp is more than the hardwood pulp in the skin side portion, and the hardwood pulp is more than the softwood pulp in the non-skin side portion. That is, the average inter-fiber distance Dp of the pulverized fibers (water-retaining fibers) on the skin side of the absorber is greater than the average inter-fiber distance Dp of the pulverized fibers (water-retaining fibers) on the non-skin side of the absorber. is also big.

Then, since the skin side portion has a larger average interfiber distance Dp than the non-skin side portion, it is possible to suppress a decrease in the liquid absorption rate in the skin side portion, and the non-skin layer with good liquid diffusibility can quickly absorb menstrual blood and the like. can be moved to the side.

Further, in the second embodiment, the total weight of the softwood pulp in the absorbent body is greater than the total weight of the hardwood pulp in the absorbent body. In this case, since the softwood pulp is more than the hardwood pulp, more water-retentive fibers having a longer average fiber length are used than when the softwood pulp is less than the hardwood pulp.

=== Third Embodiment ===
Next, the differences between the third embodiment and the above-described embodiments will be described.

The difference in the third embodiment is the blending of the hardwood pulp and the softwood pulp in the absorber. When comparing the side part, comparing the left side and right side when bisecting the width direction, and comparing the skin side and non-skin side when bisecting the thickness direction In both cases, the difference is within 10%, and the total weight of the softwood pulp is compared between the front side and the back side when the longitudinal direction is divided into two equal parts. When comparing the left side and right side when bisecting the width direction, or when comparing the skin side and non-skin side when bisecting the thickness direction. Also, the difference is within 10%.

As a result, hardwood pulp and softwood pulp are uniformly mixed in the entire absorber, so that fit to the body and diffusibility of menstrual blood and the like can be improved while suppressing deformation of the absorber as a whole.

=== Fourth Embodiment ===
Next, differences between the fourth embodiment and the above-described embodiments will be described.

The difference in the fourth embodiment is that the absorber is formed of a pulverized fiber layer, and has a hardwood layer with a lot of hardwood pulp and a softwood layer with a lot of softwood pulp on the non-skin side of the hardwood layer. The layer is provided inside the softwood layer in the plane direction.

Such a configuration of the hardwood layer and the softwood layer can be realized, for example, by preparing another set of rotating drums 70 or the like shown in FIG. 3 and providing them continuously in the production line. In the case of such a production line, the outer edge of the recess 71 on the upstream side is made larger than the outer edge of the recess 71 on the downstream side. Then, on the upstream side, a softwood layer absorbent body is formed and placed on the base material conveyed by the conveyor, and on the downstream side, a hardwood layer absorbent body is formed and placed on the softwood layer absorbent body. Thus, the absorbent body according to the fourth embodiment can be manufactured. Since two rotating drums are used, as described above, both the hardwood pulp roll and the softwood pulp roll can be pulverized with the two rotating drums, and the hardwood layer and the softwood layer can be produced by changing the ratio. can.

That is, the absorber according to the fourth embodiment is formed by laminating pulverized fibers, and includes a hardwood layer in which the weight of the hardwood pulp is heavier than the weight of the softwood pulp, and a hardwood layer in which the weight of the softwood pulp is higher than the weight of the hardwood pulp. It has a heavy softwood layer, the hardwood layer is provided on the skin side of the softwood layer, and when viewed in the thickness direction, the outer edge of the hardwood layer is located inside the outer edge of the softwood layer. ing.

By arranging the broadleaf tree layer closer to the skin than the softwood layer, the rewetting property is improved in the vicinity of the vaginal opening or the urination opening, and the softwood layer is arranged in a wider range when viewed in the thickness direction than the hardwood layer. As a result, the outer peripheral area of the absorbent body is less likely to twist, thereby further suppressing the loss of shape, and suppressing the decrease in liquid diffusibility in the outer peripheral area of the absorbent body. can be suppressed)

=== Other Embodiments ===
The above-described embodiments are intended to facilitate understanding of the present invention, and are not intended to limit and interpret the present invention. The present invention can be modified and improved without departing from its spirit, and it goes without saying that the present invention includes equivalents thereof.

Further, in the above-described embodiment, hardwood pulp and coniferous wood pulp are used as the water-retentive fibers of the absorbent body 10, but the present invention is not limited to this. Non-wood pulp such as (for example, cotton linter); regenerated cellulose fiber such as rayon fiber; semi-synthetic fiber such as acetate fiber, and the like may also be used. Further, the absorbent body 10 may contain thermoplastic resin fibers (corresponding to synthetic fibers). For example, when thermoplastic resin fibers are included, it is desirable that the content be large on the skin side of the absorbent body and that the thermoplastic resin fibers are fused to each other.

That is, when the absorbent body has synthetic fibers, the synthetic fibers are contained more in the skin side part than in the non-skin side part of the absorbent body when divided into two equal parts in the thickness direction, and in the skin side part of the absorbent body, It is desirable to have portions where the synthetic fibers are fused together. As a result, since the synthetic fibers are connected and fused to each other on the skin side, the liquid diffusibility is improved in the skin side, and the rigidity is improved, thereby suppressing deformation.

Rayon fibers, which are water-retaining fibers, may also be used as fibers added to or substituted for the thermoplastic resin fibers. That is, the absorbent body may have at least one of rayon fibers and synthetic fibers. Then, at least one of the rayon fiber and the synthetic fiber improves the rigidity of the absorbent core, thereby suppressing the shape loss of the absorbent core and suppressing deterioration of fit.

Moreover, when thermoplastic resin fibers are included, it is desirable that the thermoplastic resin fibers are fused together in the pressing portion that presses the absorbent core integrally in the thickness direction. In other words, the absorbent core contains a plurality of thermoplastic fibers and has a pressing portion that integrally presses the absorbent core in the thickness direction. It is desirable to be

That is, when forming the compressed portion, the thermoplastic fibers are fused to each other, so that the integrity between the top sheet 3 and the absorbent body 10 is strengthened, and the shape of the absorbent body 10 is easily stabilized. As a result, for example, even when the wearer moves the body significantly while wearing the napkin, the absorber 10 can be easily prevented from losing its shape or deteriorating in water absorbency.

1 sanitary napkin (absorbent article)
2 side seat 3 top seat 4 second seat (skin side seat)
4f second sheet fibers 5 back sheet 5a thread rubber (elastic member)
6 cover sheet 10 absorber (absorbent core)
10f Hardwood water-retaining fiber 20 Napkin main body 21 Adhesive part for main body (preventing slippage)
30 Wing part 31 Adhesive part for wing part 40 Squeezing part 50L Hardwood pulp (hardwood water-retentive fiber)
50N softwood pulp (softwood water-retentive fiber)
70 rotating drum 71 concave portion 72 suction portion,
80 material supply unit 80a hood,
81 particle feeder

Claims (14)

having a longitudinal direction, a width direction, and a thickness direction perpendicular to each other;
An absorbent article comprising a liquid-permeable topsheet, a liquid-impermeable backsheet, and an absorbent core provided between the topsheet and the backsheet,
The absorbent core has pulverized fibers,
The pulverized fibers contain hardwood water-retaining fibers made from hardwoods and softwood water-retaining fibers made from softwoods,
At least at the center in the thickness direction of the absorbent core, the pulverized fibers are entangled with each other to form the absorbent core without using an adhesive,
In the hardwood water-retentive fiber, the total weight of the skin-side portion of the absorbent core when divided into two equal parts in the thickness direction is greater than the total weight of the non-skin-side portion of the absorbent core,
The soft water-retentive fiber is characterized in that the total weight of the non-skin side portion of the absorbent core when divided into two equal parts in the thickness direction is larger than the total weight of the skin side portion of the absorbent core. absorbent article. The absorbent article according to claim 1,
wherein the average interfiber distance of the pulverized fibers on the skin side of the absorbent core is smaller than the average interfiber distance of the pulverized fibers on the non-skin side of the absorbent core. absorbent article. The absorbent article according to claim 1 or claim 2,
An absorbent article, wherein the absorbent article is provided with an elastic member that expands and contracts in the longitudinal direction. having a longitudinal direction, a width direction, and a thickness direction perpendicular to each other;
An absorbent article comprising a liquid-permeable topsheet, a liquid-impermeable backsheet, and an absorbent core provided between the topsheet and the backsheet,
The absorbent core has pulverized fibers,
The pulverized fibers contain hardwood water-retaining fibers made from hardwoods and softwood water-retaining fibers made from softwoods,
At least at the center in the thickness direction of the absorbent core, the pulverized fibers are entangled with each other to form the absorbent core without using an adhesive,
In the hardwood water-retentive fiber, the total weight of the non-skin side portion of the absorbent core when divided into two equal parts in the thickness direction is larger than the total weight of the skin side portion of the absorbent core,
The soft water-retentive fiber is characterized in that the total weight of the skin-side portion of the absorbent core when divided into two equal parts in the thickness direction is larger than the total weight of the non-skin-side portion of the absorbent core. absorbent article. The absorbent article according to claim 4,
wherein the average inter-fiber distance of the pulverized fibers on the skin side of the absorbent core is greater than the average inter-fiber distance of the pulverized fibers on the non-skin side of the absorbent core. absorbent article. The absorbent article according to any one of claims 1 to 5,
An absorbent article, wherein the total weight of the hardwood water-retaining fibers in the absorbent core is greater than the total weight of the softwood water-retaining fibers in the absorbent core. The absorbent article according to any one of claims 1 to 5,
An absorbent article, wherein the total weight of the softwood water-retaining fibers in the absorbent core is greater than the total weight of the hardwood water-retaining fibers in the absorbent core. having a longitudinal direction, a width direction, and a thickness direction perpendicular to each other;
An absorbent article comprising a liquid-permeable topsheet, a liquid-impermeable backsheet, and an absorbent core provided between the topsheet and the backsheet,
The absorbent core has pulverized fibers,
The pulverized fibers contain hardwood water-retaining fibers made from hardwoods and softwood water-retaining fibers made from softwoods,
At least at the center in the thickness direction of the absorbent core, the pulverized fibers are entangled with each other to form the absorbent core without using an adhesive,
The absorbent core is formed by laminating the pulverized fibers,
The absorbent core has a hardwood layer in which the weight of the hardwood water-retaining fibers is heavier than the weight of the softwood water-retaining fibers, and a softwood layer in which the weight of the softwood water-retaining fibers is heavier than the weight of the hardwood water-retaining fibers. and
The broadleaf tree layer is provided closer to the skin than the coniferous tree layer,
An absorbent article, wherein the outer peripheral edge of the broadleaf tree layer is located inside the outer peripheral edge of the softwood layer when viewed in the thickness direction. The absorbent article according to any one of claims 1 to 8,
The absorbent article has a skin-side sheet made of fibers,
The skin-side sheet is provided adjacent to the skin side of the absorbent core,
At least part of the hardwood water-retentive fibers protrude from the skin-side surface of the absorbent core and extend to the interior of the skin-side sheet,
An absorbent article, wherein at least part of the hardwood water-retentive fibers are in contact with fibers of the adjacent skin-side sheet inside the skin-side sheet. having a longitudinal direction, a width direction, and a thickness direction perpendicular to each other;
An absorbent article comprising a liquid-permeable topsheet, a liquid-impermeable backsheet, and an absorbent core provided between the topsheet and the backsheet,
The absorbent core has pulverized fibers,
The pulverized fibers contain hardwood water-retaining fibers made from hardwoods and softwood water-retaining fibers made from softwoods,
At least at the center in the thickness direction of the absorbent core, the pulverized fibers are entangled with each other to form the absorbent core without using an adhesive,
The absorbent core has a synthetic fiber,
The synthetic fibers are contained more in the skin side than in the non-skin side of the absorbent core when divided into two equal parts in the thickness direction,
An absorbent article, wherein said skin-side portion of said absorbent core has a portion where said synthetic fibers are fused to each other. The absorbent article according to any one of claims 1 to 10,
The absorbent article comprises a cover sheet,
The cover sheet is joined to the absorbent core adjacent to the non-skin side of the absorbent core,
The backsheet is joined to the coversheet adjacent to the non-skin side of the coversheet,
On the non-skin side of the backsheet, a plurality of anti-slippages extending in the first direction are provided at intervals in a second direction orthogonal to the first direction,
The absorbent article, wherein the minimum value of the spacing in the second direction of the anti-slippage is longer than the average fiber length of the hardwood water-retentive fibers. The absorbent article according to any one of claims 1 to 11,
The average fiber width of the hardwood water-retentive fiber is 15 μm or less,
The number of hardwood water-retentive fibers contained per unit area of the absorbent core is 300/mm2 or more and less than 2500/mm2,
An absorbent article comprising a superabsorbent polymer between a plurality of said hardwood water-retentive fibers. The absorbent article according to any one of claims 1 to 12,
The standard deviation of the fiber length of the hardwood water-retentive fiber is 0.27 or less,
The absorbent article, wherein the standard deviation of the fiber width of the hardwood water-retentive fiber is 7.55 or less. The absorbent article according to claim 13,
The value obtained by adding the standard deviation of the fiber length of the hardwood water-retainable fibers to the average fiber length of the hardwood water-retainable fibers is smaller than twice the average fiber length of the hardwood water-retainable fibers,
The value obtained by subtracting the standard deviation of the fiber length of the hardwood water-retainable fibers from the average fiber length of the hardwood water-retainable fibers is greater than half the average fiber length of the hardwood water-retainable fibers. An absorbent article characterized by:

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