JP2021083543A - Absorbent article - Google Patents

Abstract

To enhance liquid diffusibility and liquid absorbency of an absorbent core (10) compared to cases employing adhesives such as air-laid.SOLUTION: The absorbent core (10) has crushed fibers (50L, 50N). The crushed fibers (50L, 50N) include hardwood water-retaining fibers (50L) made from hardwood and softwood water-retaining fibers (50N) made from softwood. The crushed fibers (50L, 50N) are intertwined in at least the thickness-direction center of the absorbent core (10). Thereby the absorbent core (10) is formed without using an adhesive.SELECTED DRAWING: Figure 3

Description

The present invention relates to absorbent articles.

As an example of an absorbable article, a sanitary napkin that absorbs excrement such as menstrual blood is known. Such sanitary napkins include an absorber (absorbent core), which contains water-retaining fibers. Usually, as the water-retaining fiber, softwood pulp fiber having a long interfiber distance is used. Further, Patent Document 1 also discloses a water-retaining fiber using a broad-leaved pulp fiber having a shorter interfiber distance than a softwood pulp fiber.

Japanese Patent Publication No. 2004-538024

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

Therefore, in the absorbent article of Patent Document 1, hardwood pulp fibers having a short interfiber distance are mixed with softwood pulp fibers and used, but they are formed by the same manufacturing method (airlaid method) as non-woven fabric and are absorbent. Adhesive is applied to the core. Then, such an adhesive may reduce the liquid absorbency and liquid diffusivity of the absorbent core.

The present invention has been made in view of the above problems, and an object of the present invention is the liquid diffusivity and liquid absorption of the absorbent core as compared with the case of using an adhesive such as airlaid. It is to enhance the sex.

The main invention for achieving the above object has a longitudinal direction, a width direction, and a thickness direction orthogonal to each other, and a liquid permeable top sheet, a liquid impermeable back sheet, the top sheet, and the above. An absorbent article comprising an absorbent core provided between the backsheet and the absorbent core, the absorbent core having crushed fibers, the crushed fibers from hardwood. Contains hardwood water-retaining fibers and softwood water-retaining fibers made of softwood, and the crushed fibers are entangled with each other at least at the center of the absorbent core in the thickness direction, so that no adhesive is used. It is an absorbent article characterized in that the absorbent core is formed in the above.

Other features of the present invention will be clarified by the description in the present specification and the accompanying drawings.

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

It is a schematic plan view which looked at the napkin 1 from the skin side in the thickness direction. It is a schematic cross-sectional view shown by the arrow AA in FIG. It is a figure for demonstrating the manufacturing method of the absorber 10. It is explanatory drawing which showed the state that the fiber of the 2nd sheet 4 and the fiber of an absorber 10 are entangled with each other. It is a figure explaining the difference in the average interfiber distance of hardwood pulp and softwood pulp. It is a figure (Table 1) which shows the average interfiber distance Dp of a fiber. It is a figure which shows the distribution of the fiber length of a hardwood pulp fiber and a softwood pulp fiber. It is a schematic plan view which looked at the napkin 1 from the non-skin side in the thickness direction. It is a figure which shows the distribution of the fiber width of the hardwood pulp and the softwood pulp.

The description of this specification and the accompanying drawings will clarify at least the following matters.

Absorbency provided between a liquid-permeable top sheet, a liquid-impermeable back sheet, and the top sheet and the back sheet, which have a longitudinal direction, a width direction, and a thickness direction orthogonal to each other. An absorbent article comprising a core, wherein the absorbent core has crushed fibers, and the crushed fibers include hardwood water-retaining fibers made of hardwood and softwood water-retaining made of softwood. The absorbent core is contained, and at least at the center of the absorbent core in the thickness direction, the crushed fibers are entangled with each other to form the absorbent core without using an adhesive. An absorbent article characterized by.

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

In such an absorbent article, in the hardwood water-retaining fiber, the total weight of the skin side portion of the absorbent core when divided into two equal parts 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 softwood water-retaining fiber is divided into two equal parts in the thickness direction is larger 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 fits the body, has improved diffusivity such as menstrual blood, and is suppressed from losing its shape.

In such an absorbent article, the average interfiber distance of the crushed fibers in the skin side portion of the absorbent core is the average fiber spacing of the crushed fibers in the non-skin side portion of the absorbent core. It is desirable that it is 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 interfiber distance is large, and it is possible to suppress the leakage of menstrual blood and the like.

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 elastic member expands and contracts, so that the surface on the skin side, which contains a large amount of soft hardwood pulp, is linked to the movement of the body, so that the fit can be further improved.

In such an absorbent article, in the hardwood water-retaining 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 the total weight of the skin side portion of the absorbent core. The total weight of the skin side of the absorbent core when divided into two equal parts in the thickness direction of the softwood water-retaining fiber is larger than the total weight of the non-skin side of the absorbent core. Is desirable.

According to such an absorbent article, the absorber can be fully utilized by increasing the liquid diffusion area on the non-skin side while suppressing the decrease in the liquid absorption rate on the skin side.

In such an absorbent article, the average interfiber distance of the crushed fibers in the skin side portion of the absorbent core is the average fiber spacing of the crushed fibers in the non-skin side portion of the absorbent core. It is desirable that it is larger than the distance.

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

In such an absorbent article, the total weight of the hardwood water-retaining fiber is when the anterior side portion and the rear side portion when the longitudinal direction is divided into two equal parts and when the width direction is divided into two equal parts. The difference is 10 in both cases of comparing the left side portion and the right side portion of the above and comparing the skin side portion and the non-skin side portion when the thickness direction is divided into two equal parts. The total weight of the coniferous water-retaining fiber is within%, and the total weight of the coniferous water-retaining fiber is the left side portion when the anterior side portion and the rear side portion when the longitudinal direction is bisected and the left side portion when the width direction is bisected. The difference is within 10% in both cases of comparing the right side part with the right side part and comparing the skin side part and the non-skin side part when the thickness direction is divided into two equal parts. It is desirable to have.

According to such an absorbent article, it is possible to improve the fit to the body and the liquid diffusibility such as menstrual blood while suppressing the shape loss 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 larger than the total weight of the softwood water-retaining fibers in the absorbent core.

According to such an absorbent article, since the amount of hardwood pulp is larger, the liquid diffusibility and rewetability can be improved as compared with the case where the amount is small.

An absorbent article, wherein the total weight of the softwood water-retaining fibers in the absorbent core is larger than the total weight of the hardwood water-retaining fibers in the absorbent core.

According to such an absorbent article, since the amount of softwood pulp is larger, the shape loss can be suppressed as compared with the case where the amount is small.

In such an absorbent article, the absorbent core is formed by laminating the crushed fibers, and in the absorbent core, the weight of the hardwood water-retaining fiber is larger than the weight of the softwood water-retaining fiber. It has a heavy hardwood layer and a softwood layer in which the weight of the softwood water-retaining fiber is heavier than the weight of the softwood water-retaining fiber, and the softwood layer is provided on the skin side of the softwood layer. When viewed in the thickness direction, it is desirable that the outer peripheral edge of the hardwood layer is located inside the outer peripheral edge of the softwood layer.

According to such an absorbent article, it is possible to further suppress the shape loss, suppress the decrease in liquid diffusivity in the outer peripheral region of the absorbent core, and suppress the leakage of excrement liquid to the outside.

Among such absorbent articles, the absorbent article has a skin-side sheet made of fibers, and the skin-side sheet is provided adjacent to the skin side surface of the absorbent core, and the broad-leaved tree. At least a part of the water-retaining fiber protrudes from the skin-side surface of the absorbent core and extends to the inside of the skin-side sheet, and inside the skin-side sheet, at least one of the broadleaf tree water-retaining fibers. 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 or the like can easily enter the inside of the absorbent core through the hardwood water-retaining fiber, and the liquid absorption rate can be improved.

In such an absorbent article, the absorbent core has synthetic fibers, and the synthetic fibers are more than the non-skin side portion of the absorbent core when divided into two equal parts in the thickness direction. It is abundantly contained in the skin side portion, and it is desirable that the skin side portion of the absorbent core has a portion in which the synthetic fibers are fused to each other.

According to such an absorbent article, since the synthetic fibers are connected to each other and fused to each other, the liquid diffusivity is improved on the skin side portion, and the shape loss is suppressed by improving the rigidity.

Among such absorbent articles, the absorbent article includes a cover sheet, and the cover sheet is joined to the absorbent core adjacent to the non-skin side of the absorbent core, and the back. The sheet is joined to the cover sheet adjacent to the non-skin side of the cover sheet, and on the non-skin side of the back sheet, a slip stopper extending in the first direction is orthogonal to the first direction. It is desirable that a plurality of the gaps are provided at intervals in two directions, and the minimum value of the spacing in the second direction of the slip prevention is larger than the average fiber length of the water-retaining fiber made of the broadleaf tree.

According to such an absorbent article, the absorbent core is easily bent between the slip stoppers, so that the absorbent article is easily linked with the movement of the body and the fit is improved.

In such an absorbent article, the average fiber width of the hardwood water-retaining fiber is 15 μm or less, and the number of the hardwood water-retaining fiber contained per unit area of the absorbent core is 300 / mm2 or more and 2500. It is less than 2 mm / mm2, and it is desirable to have a highly absorbent polymer between the plurality of hardwood water-retaining fibers.

According to such an absorbent article, the excrement liquid contained in the hardwood pulp is easily drawn into the highly absorbent polymer between the hardwood pulps, so that the liquid return can be reduced even when the excrement liquid is absorbed multiple 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 fiber is 0.27 or less, and the standard deviation of the fiber width of the hardwood water-retaining fiber is 7.55 or less.

According to such an absorbent article, since it is easy to maintain a uniform fiber density in the absorber, there is little bias in the plane direction and it is easy to diffuse concentrically.

In such an absorbent article, the value obtained by adding the standard deviation of the fiber length of the broad-leaved water-retaining fiber to the average fiber length of the broad-leaved water-retaining fiber is twice the average fiber length of the broad-leaved water-retaining fiber. The value obtained by subtracting the standard deviation of the fiber length of the broad-leaved tree water-retaining fiber from the average fiber length of the broad-leaved tree water-retaining fiber is ½ of the average fiber length of the broad-leaved tree water-retaining fiber. Is also desirable.

According to such an absorbent article, since it is easy to maintain a uniform fiber density in the absorber, there is little bias in the plane direction and it is easy to diffuse concentrically.

In such an absorbent article, the absorbent core contains a plurality of thermoplastic fibers and has a squeezing portion for integrally squeezing the absorbent core in the thickness direction. , It is desirable that the thermoplastic fibers are fused to each other.

According to such an absorbent article, even when the wearer moves his / her body significantly, it is possible to easily prevent the absorber 10 from losing its shape or deteriorating water absorption.

=== 1st Embodiment ===
<< Basic configuration of sanitary napkins >>
A sanitary napkin 1 (hereinafter, also simply referred to as a napkin 1) will be described as an example of the 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 a so-called vaginal discharge sheet (for example, panty liner), a light incontinence pad, and the like. It is not limited to sanitary napkins.

FIG. 1 is a schematic plan view of the napkin 1 as viewed from the skin side in the thickness direction. FIG. 2 is a schematic cross-sectional view shown by arrow AA in FIG. Further, in the following description, each direction is defined as shown in FIGS. 1 and 2. That is, the "longitudinal direction" along the product longitudinal direction of the napkin 1, the "width direction" orthogonal to the longitudinal direction along the product short direction of the napkin 1, and the "thickness" orthogonal to the longitudinal direction and the width direction, respectively. "Direction" is defined. Of the longitudinal directions, the direction that is the ventral side of the wearer when the napkin 1 is used is defined as the "front side", and the direction that is the dorsal side 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 referred to as the "skin side (upper side)", and the opposite side is referred to as the "non-skin side (lower side)".

The napkin 1 is a vertically elongated sheet-like member in a plan view, and a pair of side sheets 2, a top sheet 3, a second sheet 4, an absorber 10, a cover sheet 6, and a back sheet 5 are in the thickness direction. It is formed by laminating in order from the skin side to the non-skin side (see FIG. 2). Each of these members is joined to a member adjacent to each other in the thickness direction with an adhesive such as a hot melt adhesive (HMA). Examples of the adhesive application pattern include an Ω pattern, a spiral pattern, and a stripe pattern.

Further, the napkin 1 has a napkin main body 20 provided with an absorber 10 and a pair of wing portions 30 extending outward from the central region in the longitudinal direction of the napkin main body 20 in the width direction. The central region in the longitudinal direction in which the wing portion 30 is provided is a region that comes into contact with the wearer's excretion port (lower crotch) when the napkin 1 is used.

The top sheet 3 is a member that comes into contact with the wearer's skin when the napkin 1 is used, and allows a liquid such as menstrual blood to permeate from the skin side to the non-skin side in the thickness direction and move it to the absorber 10. Therefore, as the top sheet 3, an appropriate liquid-permeable flexible sheet such as an air-through non-woven fabric is used.

The second sheet 4 (corresponding to the skin side sheet) is a sheet made of liquid-permeable fibers, and the same air-through non-woven fabric as the top sheet 3 can be exemplified. The second sheet 4 is provided on the skin side surface of the absorber 10 (adjacent to the skin side surface), and plays a role of preventing the reversion of excrement such as menstrual blood, improving the diffusion of excrement, and improving the cushioning property. .. However, the napkin 1 does not have to have the second sheet 4 (for example, the top sheet 3 may replace it).

The cover sheet 6 may be a liquid-permeable sheet or a liquid-impermeable sheet, and examples thereof include tissue paper, SMS (spun bond / melt blown / spun bond) non-woven fabric, and the like. The cover sheet 6 is provided between the absorber 10 and the back sheet 5. That is, the napkin 1 includes the cover sheet 6, the cover sheet 6 is joined to the absorber 10 adjacent to the non-skin side of the absorber 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 does not have to have the cover sheet 6 (for example, the back sheet 5 may replace it).

The back sheet 5 prevents the liquid that has passed through the top sheet 3 and absorbed by the absorber 10 from seeping out to the clothing side (non-skin side) such as underwear when the napkin 1 is used. For the back sheet 5, an appropriate liquid-impermeable flexible sheet such as a polyethylene (PE) resin film is used. The plane size of the top sheet 3 and the back sheet 5 is larger than that of the absorber 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. Then, by expanding and contracting the rubber thread 5a, the fit to the body can be further improved (details will be described later). The elastic member is not limited to the rubber thread 5a, and for example, an elastic 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 non-woven fabric and the same air-through non-woven fabric as the top sheet 3.

Then, as shown in FIGS. 1 and 2, the outer peripheral edges of the side sheet 2 and the top sheet 3 and the back sheet 5 are bonded to each other by adhesion or welding, so that the sheets are absorbed between the sheets. Body 10 is held. Further, the pair of side seats 2 extend from both side portions in the width direction of the top sheet 3 to the outside in the width direction, and form a pair of wing portions 30 together with the back seat 5.

On the non-skin side surface of the napkin body 20 in the thickness direction (that is, the non-skin side surface of the back sheet 5), an appropriate adhesive (for example, hot melt adhesive) is applied to a plurality of strip-shaped regions along the longitudinal direction. An adhesive portion 21 for the main body (corresponding to a slip stopper) formed thereby is provided (see FIGS. 2 and 8). That is, on the non-skin side of the back sheet 5, a plurality of slip stoppers extending in the longitudinal direction are provided at intervals in the width direction. When the napkin 1 is used, the adhesive portion 21 for the main body is attached to the side surface of the skin such as underwear, whereby the napkin 1 is fixed to the underwear or the like.

Similarly, a wing portion adhesive portion 31 is provided on the non-skin side surface of each wing portion 30 in the thickness direction (that is, the non-skin side surface of the back sheet 5) (see FIG. 2). When the napkin 1 is used, the wing portion 30 is bent toward the non-skin side, and the adhesive portion 31 for the wing portion is attached to the non-skin side surface of the underwear or the like, whereby the napkin 1 is fixed to the underwear or the like.

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

Further, the napkin 1 is provided with a plurality of squeezed portions 40 (recesses). The squeezed portion 40 is a portion where the top sheet 3, the second sheet 4, and the absorber 10 are integrally squeezed and recessed from the skin side to the non-skin side in the thickness direction, and the density of the absorber 10 is the same. It is a part higher than the surrounding density. That is, the top sheet 3, the second sheet 4, and the absorber 10 have uneven portions on the side surface of the skin. Then, a flow of menstrual blood or the like is generated 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 absorber 10 has water-retaining fibers that absorb liquid, and is formed into a vertically elongated shape in a plan view. As the water-retaining fiber according to the present embodiment, wood of softwood pulp fiber (hereinafter, also referred to as softwood pulp, corresponding to softwood water-retaining fiber) and hardwood pulp fiber (hereinafter, also referred to as broad-leaved pulp, corresponding to broad-leaved water-retaining fiber). Pulp is crushed and used. Then, the absorber 10 is formed by entwining the crushed fibers (water-retaining fibers) without using an adhesive.

Examples of softwood pulp and hardwood pulp include wood pulp obtained by crushing Southern Yellow Pine as softwood pulp and wood pulp obtained by crushing eucalyptus as hardwood pulp.

Further, the absorber 10 may have a liquid-absorbing granular material such as a highly absorbent polymer (so-called SAP).

As a method for producing the absorber 10, a method of accumulating crushed pulp, a highly absorbent polymer, or the like is known.

FIG. 3 is a diagram for explaining a method of manufacturing the absorber 10. Here, a case where the absorbent body 10 contains water-retaining fibers (coniferous pulp and hardwood pulp) and a highly absorbent 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 an absorber material. When the rotary drum 70 rotates and the recess 71 enters the material supply section 80, the absorber material supplied from the material supply section 80 is deposited (accumulated) in the recess 71 by the suction of the suction section 72.

The material supply unit 80 with the hood 80a is formed so as to cover the upper part of the rotary drum 70, and the material supply unit 80 is crushed pulp (crushed fiber) obtained by crushing a pulp sheet with a crusher (not shown). Is supplied to the recess 71 by air transportation. Then, at this time, the crushed pulp is supplied so as to be intertwined with each other (then, the crushed pulp is firmly intertwined by the suction of the suction unit 72). Further, the material supply unit 80 includes a particle supply unit 81 for supplying superabsorbent polymer particles, and supplies superabsorbent polymer particles to the recess 71. The water-retaining fiber and the superabsorbent polymer particles are deposited in the recess 71 in a mixed state, and the absorber 10 is formed in the recess 71.

When the recess 71 accommodating the absorber 10 reaches the bottom of the drum due to the further rotation of the rotating drum 70, the absorber 10 is disengaged from the recess 71, and the base material (cover sheet 6, etc.) 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 absorber 10 in order to join the second sheet 4 and the absorber 10, and the second sheet 4 is transferred to the absorber 10. Be pressed. Then, the absorber 10 has an adhesive on the surface layer portion (the surface and the portion where the adhesive penetrates into the inside of the absorber 10) on the skin side, but in general, such an adhesive is the absorber. It does not reach the center in the thickness direction of 10.

As the absorber described in Patent Document 1, a pulp fiber, a thermoplastic resin fiber, a powder, or the like formed into a sheet by a manufacturing method (airlaid method) similar to that of a non-woven fabric is used. An adhesive is applied to the airlaid (that is, the adhesive is present throughout the absorber), and by using such an adhesive, the rigidity of the absorber is higher than that of the absorber 10 manufactured by the manufacturing method of FIG. Is increased, and the liquid diffusivity and liquid absorption of the excrement liquid are reduced. That is, when the absorber 10 is manufactured by the manufacturing method shown in FIG. 3, the rigidity is low (soft) and the liquid diffusivity and the liquid are lower than those of the absorber manufactured by the airlaid method, at least in the center in the thickness direction. The absorber 10 having high absorbency can be produced.

In other words, the adhesive in the absorber reduces the liquid diffusivity and liquid absorbency of the excrement, so by forming the absorber 10 without using the adhesive, when an adhesive such as airlaid is used. In comparison, the liquid diffusibility and the liquid absorbency can be enhanced at least in the center of the absorber 10 in the thickness direction. Further, the absorber 10 containing hardwood pulp is softer and has better liquid absorbency than the absorber 10 containing only softwood pulp, and the absorber 10 containing softwood pulp is compared with the absorber 10 containing only hardwood pulp. Is hard to twist and crumble. That is, by including both hardwood pulp and softwood pulp in the absorber 10, the softwood pulp becomes a skeleton and the hardwood pulp is filled between them, so that the napkin is soft, has good absorbency, and is hard to twist and crumble. 1 can be provided.

That is, the absorber 10 has crushed fibers, and the crushed fibers include hardwood pulp made of hardwood and softwood pulp made of softwood, and the absorber 10 is at least in the thickness direction. At the center, the crushed fibers are entangled with each other to form the absorber 10 without using an adhesive.

Further, by pressing the second sheet 4 and the absorber 10 in the thickness direction, the water-retaining fibers of the absorber 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 absorber 10 are entangled with each other. As will be described later, since hardwood pulp is thin, entanglement that enters between fibers occurs, but since softwood pulp is thick, it is difficult to enter between fibers and entanglement that is difficult to occur (or does not occur). That is, the water-retaining fiber of FIG. 4 represents hardwood pulp.

Looking at FIG. 4, inside the second sheet 4, the hardwood water-retaining fiber 10f of the absorber 10 (indicated by a black line in the enlarged view) contacts the fiber 4f of the second sheet 4 (indicated by a white line in the enlarged view). doing. That is, at least a part of the hardwood water-retaining fiber 10f protrudes from the skin-side surface of the absorber 10 and extends to the inside of the second sheet 4, and inside the second sheet 4, at least a part of the hardwood water-retaining fiber 10f Part of it is in contact with the fibers of the second sheet 4.

By the contact between the fibers, the excrement liquid easily enters the inside of the absorber 10 from the fibers 4f of the second sheet 4 through the hardwood water-retaining fibers 10f, so that the liquid absorption rate can be increased. In addition, since the water-retaining fibers are in a state of being caught on the skin-side sheet, it is possible to suppress the twisting of the absorber 10 and the shape loss of the absorber 10.

Further, it is desirable that the thickness of the absorber 10 is 2 mm or more and 10 mm or less. If the thickness of the absorber 10 is less than 2 mm, it is too thin and twisted, and if it exceeds 10 mm, it is too hard and the wearer may feel uncomfortable.

Further, the fiber number density of hardwood pulp is larger than that of softwood pulp because it is thinner and the interfiber distance 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 included per unit area in the case of a finely packed structure by the fiber thickness + the average distance between fibers. .. Looking at these estimated values, the fiber number density of hardwood pulp is 1182.2 fibers / mm ^2, which is about 6 times the fiber number density of softwood pulp (200.3 fibers / mm ^2). Therefore, when hardwood pulp is used, the density can be increased as compared with the case where softwood pulp is used.

Fiber number density is desirably 2500 lines / mm less than ² 300 lines / mm ² or more. If the fiber number density is ^{less than 300 fibers / mm 2} , the absorber 10 becomes faint and becomes liable during use, resulting in a decrease in the absorber area and easy leakage. If the density of the number of fibers is 2500 fibers / mm ² or more, the absorber 10 will be finished too hard, and the feeling of discomfort during use will increase. If the number of fibers density 300 lines / mm ² or more 2,500 / mm ² under a, it is possible to enhance the capillary effect, also it allows thinner and softening, it is possible to enhance the absorbency.

Further, the density of fibers is preferably higher in hardwood pulp than in softwood pulp. Then, the capillary effect can be increased while maintaining the softness of the absorber 10.

<< About the combination of hardwood pulp and softwood pulp >>
Next, the composition of the hardwood pulp and the softwood pulp in the absorber 10 will be described. In the present embodiment, on the skin side of the absorber 10, the amount of hardwood pulp is larger than that of the softwood pulp, and on the non-skin side of the absorber 10, the amount of softwood pulp is larger than that of the hardwood pulp. (Measured with an electronic balance HF-300 manufactured by Kensei Kogyo Co., Ltd.). That is, in the hardwood pulp, the total weight of the skin side portion of the absorber 10 when divided into two equal parts in the thickness direction is larger than the total weight of the non-skin side portion of the absorber 10, and the softwood pulp is in the thickness direction. The total weight of the non-skin side portion of the absorber 10 when divided into two equal parts is larger than the total weight of the skin side portion of the absorber 10.

Such adjustment of the composition in the thickness direction can be realized, for example, by manufacturing the absorber 10 as follows. First, a hardwood pulp roll and a softwood pulp roll are prepared. Then, each pulp roll is crushed with a saw mill or the like, and each pulp roll is manufactured by adjusting the mixing ratio between the crushing and the pattern plate. Further, it is preferable to use two saw mills, but this is an example. Each pulp is crushed by one saw mill, and each other is mixed at the stage where the hardwood pulp and the softwood pulp are mixed between the crushing and the lamination. The ratio of Then, on the skin side of the absorber 10 (bottom side of the recess 71), there is more hardwood pulp than the softwood pulp, and on the non-skin side of the absorber 10 (open side of the recess 71), there is more softwood pulp than the softwood pulp. can do.

According to such a napkin 1, since the hardwood pulp is abundant on the skin side, the napkin 1 is easy to bend and is soft and fits the body, and the liquid diffusivity such as menstrual blood is improved, and the softwood pulp is on the non-skin side. Since it is abundant in the part, a skeleton is formed on the non-skin side and the shape loss is suppressed. That is, it is possible to provide a napkin 1 that fits the body, has improved diffusivity such as menstrual blood, and is suppressed from losing its shape. In addition, since the absorbent core is provided with hardwood pulp, the effect of trapping menstrual blood and the like once drawn in can be produced, and the rewetability can be enhanced (returning of liquid can be reduced).

Further, in the present embodiment, the total weight of the hardwood pulp in the absorber 10 is larger than the total weight of the softwood pulp in the absorber 10. Then, since the amount of hardwood pulp is larger than that of softwood pulp, the average interfiber distance (described later) can be shortened as compared with the case where the amount is small. When the average interfiber distance is short, the capillary phenomenon is likely to occur, so that the liquid diffusibility can be improved and the liquid return (rewet) can be reduced.

Further, as described above, the back sheet 5 is provided with a rubber thread 5a (elastic member) that expands and contracts in the longitudinal direction. Then, as in the present embodiment, the absorber 10 containing a large amount of hardwood pulp expands and contracts with the thread rubber 5a on the skin side, so that the absorber 10 is deformed along the curve of the body, so that it fits the body. It can further improve the sex (coniferous pulp is hard and hard to deform, and 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).

<< Evaluation of average interfiber distance >>
Next, the average interfiber distance between hardwood pulp and softwood pulp was evaluated by the following method.

Prepare a sample of 100% hardwood pulp, 100% softwood pulp, and 50% hardwood pulp + 50% softwood pulp as a sample, and use the 3D image connection function of the microscope (VEYENCE VHX-2000, lens VH-Z20W aperture open). Using this, a magnified image (for example, 500 times for hardwood and 100 times for conifer) is obtained from the surface of the sample to a depth of 100 μm, and the focused fiber is based on the magnified image. The outside of was extracted. The surface formed there is used as 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, since the diameter of the maximum inscribed circle in each fiber space is the interfiber distance, the average interfiber distance of softwood pulp is long, and the average interfiber distance of hardwood pulp is short.

FIG. 6 is a diagram showing the average interfiber distance Dp of the fibers. As shown in FIG. 6, 100% hardwood pulp has a smaller average interfiber distance Dp than 100% softwood pulp. And, 50% of hardwood pulp + 50% of softwood pulp is larger than 100% of hardwood pulp and smaller than 100% of softwood. That is, when the composition of hardwood pulp and softwood pulp is changed, the average interfiber distance Dp of the fibers also changes.

In the absorber 10, the amount of hardwood pulp is larger than that of softwood pulp on the skin side, and the amount of softwood pulp is larger than that of softwood pulp on the non-skin side. That is, the average interfiber distance Dp of the crushed fibers (water-retaining fibers) on the skin side of the absorber 10 is the average interfiber distance of the crushed fibers (water-retaining fibers) on the non-skin side of the absorber 10. It is smaller than Dp.

Then, since the average interfiber distance Dp on the skin side is smaller than that on the non-skin side, menstrual blood and the like are diffused on the skin side and the movement of menstrual blood and the like to the non-skin side is reduced by the capillary effect. 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 interfiber distance Dp is large, and it is possible to suppress the leakage of menstrual blood and the like.

The evaluation of the average interfiber distance Dp is performed, for example, by peeling off the use surface side sheet (second sheet 4) of the absorber 10 on the skin side portion and using the above-mentioned microscope on the exposed surface of the absorber 10. The average interfiber distance Dp was measured with the above method, and on the non-skin side, the unused surface side sheet (cover sheet 6) of the absorber 10 was peeled off, and the exposed surface of the absorber 10 was used with the above-mentioned microscope. It is possible by measuring the average interfiber distance Dp with.

<< About the average fiber length of water-retaining fibers >>
Next, the relationship between the average fiber length of the water-retaining fiber and the adhesive portion 21 for the main body portion will be described. FIG. 7 is a diagram showing the distribution of fiber lengths of hardwood pulp fibers and softwood pulp fibers. The horizontal axis shows the fiber length (mm), and the vertical axis shows the frequency (%). As shown in the figure, the average fiber length of softwood pulp is 2.5 mm, and the distribution width of the fiber length is wide (fibers of 3 mm or more are included. The 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 the fiber length is narrow (standard deviation is 0.27).

The average fiber length means a length-weighted average fiber length measured by the central fiber length (Cont). The length-weighted average fiber length is measured as an L (l) value by Kajaani FiberLab Fiber Properties (offline) [kajaaniFiberLab fiber products (off-line)] manufactured by metso automation. This is also the method recommended by JIS P 8226-2 (the method for measuring the fiber length by the pulp-engineering automatic analysis method, which conforms to the non-polarizing method). Further, as described in the JIS evaluation method, the average fiber length and the fiber width described later are the results measured excluding the fiber mass.

FIG. 8 is a schematic plan view of the napkin 1 as 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 adhesive portion 21 for the main body extending in the longitudinal direction (corresponding to the first direction) is in the width direction (first direction) orthogonal to the longitudinal direction (first direction). A plurality of intervals of 21 g are provided in (corresponding to two directions), and the minimum value of the interval of 21 g in the width direction (second direction) is larger than the average fiber length of the water-retaining fibers made of hardwood.

Therefore, when the force of deformation from the underwear is received, the water-retaining fibers straddling the installed portion and the non-installed portion of the adhesive portion 21 for the main body portion can be reduced, and the absorber 10 is between the adhesive portion 21 for the main body portion. Because it becomes easy to bend, the napkin 1 easily interlocks with the movement of the body and the fit is improved.

It should be noted that a plurality of adhesive portions 21 for the main body portion shown in FIG. 8 are provided so as to extend in the longitudinal direction with an interval of 21 g in the width direction, but the present invention is not limited to this, and for example, the adhesive portions 21 extend in the width direction. It may be provided at intervals in the longitudinal direction.

<< About the average fiber width of water-retaining fibers >>
Next, the average fiber width of the water-retaining fiber will be described. The measurement is carried out in the same manner as the above-mentioned average fiber length, and is measured as Fiber Wide.

FIG. 9 is a diagram showing the distribution of average fiber widths of hardwood pulp and softwood pulp. The horizontal axis shows the fiber width (μm), and the vertical axis shows the frequency (%). As shown in FIG. 9, the average fiber width of 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 (see the figure below), and the distribution width of the fiber width is narrow (standard deviation is 7.55). In the napkin 1 of the present embodiment, since the absorber 10 uses hardwood pulp, the average fiber width of the water-retaining fibers is shorter than that in the case where only softwood pulp is used.

The average fiber width of hardwood pulp is not more 15μm or less, a fiber number density of less than 300 lines / mm ² or more 2,500 / mm ² as described above, with the superabsorbent polymer between the hardwood pulp Is desirable. Then, the hardwood pulp, which is characterized by the fact that the fibers are not easily entangled and the fiber width is short, is densely packed, so that the fibers are likely to contain excrement liquid, and the excrement liquid contained in the hardwood pulp is between the hardwood pulps. Since it is easily drawn into the highly absorbent polymer, it is possible to reduce the liquid return even when the excrement liquid is absorbed a plurality of times.

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

When the distribution width is narrow and the standard deviation is small as described above, it is easy to maintain a uniform fiber density in the absorber, so that there is little bias in the plane direction and it is easy to diffuse concentrically.

Looking at the average fiber length and average fiber width of the water-retaining fibers in this way, the softwood pulp is thicker and longer than the hardwood pulp, so the pulps are easily entangled with each other and form a solid skeleton. To do. On the other hand, since hardwood pulp is thin and short, it is difficult for the pulp to entangle with each other, but it is easy to get in between the softwood pulp. It is possible to provide a napkin 1 having high liquid diffusivity and high rewetability.

=== Second embodiment ===
Next, with respect to the second embodiment, the same points as those of the first embodiment described above will be omitted, and the differences from the first embodiment will be described.

The difference from the first embodiment of the second embodiment is the combination of the hardwood pulp and the softwood pulp in the absorber. In the second embodiment, the softwood pulp is more than the hardwood pulp on the skin side of the absorber. On the non-skin side of the absorber, hardwood pulp is often more than softwood pulp. That is, the total weight of the non-skin side of the absorber when the hardwood pulp is divided into two equal parts in the thickness direction is larger than the total weight of the skin side of the absorber, and the softwood pulp is second grade in the thickness direction. The total weight of the skin side of the absorber when divided is greater than the total weight of the non-skin side of the absorber.

Then, since the softwood pulp is abundant on the skin side, the strike-through property (which is liquid-permeable, and the liquid absorption rate is unlikely to decrease when the strike-through property is high) is improved, and the hardwood pulp is abundant on the non-skin side. Therefore, the liquid drawing property and the liquid diffusing property are improved. That is, the absorber can be fully utilized by increasing the liquid diffusion area on the non-skin side while suppressing the decrease in the liquid absorption rate on the skin side. Further, since the absorber is provided with hardwood pulp, the effect of trapping menstrual blood and the like once drawn can be produced, and the rewetability can be enhanced.

As for the average interfiber distance Dp, as described above, the average interfiber distance Dp of the broadleaf pulp and the softwood pulp is different (see FIGS. 5 and 6). The average interfiber distance Dp of is also changed. In the absorber according to the second embodiment, the softwood pulp is more than the hardwood pulp on the skin side, and the hardwood pulp is more than the hardwood pulp on the non-skin side. That is, the average interfiber distance Dp of the crushed fibers (water-retaining fibers) on the skin side of the absorber is larger than the average interfiber distance Dp of the crushed fibers (water-retaining fibers) on the non-skin side of the absorber. Is also big.

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

Further, in the second embodiment, the total weight of the softwood pulp in the absorber is larger than the total weight of the hardwood pulp in the absorber. Then, since the amount of softwood pulp is larger than that of hardwood pulp, more water-retaining fibers having a long average fiber length are used and more fiber entanglement is performed than when the amount is small, so that the shape of the absorber can be suppressed from being lost.

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

The difference in the third embodiment is the composition of the hardwood pulp and the softwood pulp in the absorber, and in the third embodiment, the total weight of the hardwood pulp is the anterior part and the rear part when the longitudinal direction is divided into two equal parts. When comparing the side part, when comparing the left side part and the right side part when the width direction is divided into two equal parts, and when comparing the skin side part and the non-skin side part when the thickness direction is divided into two equal parts. In both cases, the difference was within 10%, and the total weight of softwood pulp was the same as when comparing the anterior and posterior parts when the longitudinal direction was divided into two equal parts. When comparing the left side and the right side when the width direction is divided into two equal parts, and when comparing the skin side part and the non-skin side part when the thickness direction is divided into two equal parts. However, the difference is within 10%.

Then, since the hardwood pulp and the softwood pulp are uniformly mixed in the whole absorber, it is possible to improve the fit to the body and the liquid diffusibility such as menstrual blood while suppressing the shape loss as a whole.

=== Fourth Embodiment ===
Next, the fourth embodiment will be described as being different from the above-described embodiment.

The difference in the fourth embodiment is that the absorber is formed of a layer of crushed fibers, and has a hardwood layer rich in hardwood pulp and a softwood layer rich in softwood pulp on the non-skin side of the hardwood layer. The layer is provided inside the coniferous layer in the plane direction.

Such a configuration of a broad-leaved tree layer and a coniferous tree layer can be realized, for example, by preparing another set of a rotating drum 70 and the like shown in FIG. 3 and continuously providing them on a 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, an absorber of the softwood layer is formed on the upstream side and placed on a base material conveyed by a conveyor, and an absorber of the broad-leaved tree layer is formed on the downstream side and placed on the absorber of the softwood layer. This makes it possible to manufacture the absorber according to the fourth embodiment. Since two rotating drums are used, as described above, both the hardwood pulp roll and the softwood pulp roll can be crushed and the ratio is changed to produce a hardwood layer and a softwood layer. it can.

That is, the absorber according to the fourth embodiment is formed by laminating crushed fibers and has a hardwood layer in which the weight of the hardwood pulp is heavier than the weight of the hardwood pulp, and the weight of the softwood pulp is larger than the weight of the hardwood pulp. It has a heavy coniferous layer, and the broad-leaved tree layer is provided on the skin side of the coniferous tree layer, and when viewed in the thickness direction, the outer peripheral edge of the broad-leaved tree layer is located inside the outer peripheral edge of the coniferous tree layer. ing.

By arranging the broad-leaved tree layer on the skin side of the coniferous tree layer, the rewetability is improved near 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 broad-leaved tree layer. By doing so, the outer peripheral region of the absorber is less likely to be twisted, the shape loss is further suppressed, and the decrease in liquid diffusivity can be suppressed in the outer peripheral region of the absorber, so that the excrement liquid leaks out (excretion liquid). Can be suppressed (leakage that occurs when stagnation occurs in one place)

=== Other embodiments ===
The above embodiment is for facilitating the understanding of the present invention, and is not for limiting the interpretation of the present invention. It goes without saying that the present invention can be modified or improved without departing from the spirit thereof, and the present invention includes an equivalent thereof.

Further, in the above-described embodiment, the broad-leaved pulp and the coniferous pulp of wood pulp are used as the water-retaining fibers of the absorber 10, but the present invention is not limited to this, and for example, bagus, kenaf, bamboo, hemp, cotton. Non-wood pulp such as (for example, cotton linter); regenerated cellulose fiber such as rayon fiber; semi-synthetic fiber such as acetate fiber may be used. Further, the absorber 10 may contain thermoplastic resin fibers (corresponding to synthetic fibers). For example, when the thermoplastic resin fiber is contained, it is desirable that the thermoplastic resin fiber is contained in a large amount on the skin side of the absorber and the thermoplastic resin fibers are fused to each other.

That is, when the absorber has synthetic fibers, the synthetic fibers are contained more in the skin side portion than in the non-skin side portion of the absorber when divided into two equal parts in the thickness direction, and in the skin side portion of the absorber, It is desirable that the synthetic fibers have a portion where they are fused to each other. Then, since the synthetic fibers are connected to each other and fused on the skin side, the liquid diffusivity is improved on the skin side, and the shape loss is suppressed by improving the rigidity.

Further, rayon fiber, which is a water-retaining fiber, may be used as the fiber added to the thermoplastic resin fiber or as a substitute fiber. That is, the absorber may have at least one of rayon fibers and synthetic fibers. Then, since the rigidity of the absorbent core is improved by at least one of the rayon fiber and the synthetic fiber, the shape of the absorbent core is suppressed from being deformed, and the deterioration of the fit can be suppressed.

Further, when the thermoplastic resin fiber is contained, it is desirable that the thermoplastic resin fibers are fused to each other in the pressing portion where the absorbent core is integrally pressed in the thickness direction. That is, the absorbent core contains a plurality of thermoplastic fibers and has a squeezed portion that integrally squeezes the absorbent core in the thickness direction. In the squeezed portion, the thermoplastic fibers are fused to each other. It is desirable to be there.

That is, when the squeezed portion is formed, the thermoplastic fibers are fused to each other, so that the top sheet 3 and the absorber 10 become more integrally and the shape of the absorber 10 becomes more stable. Thereby, for example, even when the wearer moves his / her body greatly while wearing the napkin, it is possible to easily prevent the absorber 10 from losing its shape or deteriorating the water absorption.

1 Sanitary napkin (absorbent article)
2 Side seat 3 Top seat 4 Second seat (skin side seat)
4f Second sheet fiber 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 (prevention of slippage)
30 Wing part 31 Adhesive part for wing part 40 Squeezed part 50L Hardwood pulp (hardwood water-retaining fiber)
50N softwood pulp (softwood water-retaining fiber)
70 Rotating drum 71 Recess 72 Suction part,
80 Material supply unit 80a Hood,
81 Particle supply unit

Claims (17)

It has a longitudinal direction, a width direction, and a thickness direction that are orthogonal to each other.
An absorbent article comprising a liquid-permeable top sheet, a liquid-impermeable back sheet, and an absorbent core provided between the top sheet and the back sheet.
The absorbent core has crushed fibers and
The crushed fibers include hardwood water-retaining fibers made of hardwood and softwood water-retaining fibers made of softwood.
An absorbent article, characterized in that the absorbent core is formed without the use of an adhesive by entwining the crushed fibers with each other at least at the center of the absorbent core in the thickness direction. The absorbent article according to claim 1.
In the hardwood water-retaining fiber, 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.
The softwood water-retaining 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 2.
The average interfiber distance of the crushed fibers in the skin side portion of the absorbent core is smaller than the average interfiber distance of the crushed fibers in the non-skin side portion of the absorbent core. Absorbent article. The absorbent article according to claim 2 or 3.
An absorbent article characterized in that the absorbent article is provided with an elastic member that expands and contracts in the longitudinal direction. The absorbent article according to claim 1.
In the hardwood water-retaining 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 softwood water-retaining 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 5.
The average interfiber distance of the crushed fibers in the skin side portion of the absorbent core is larger than the average interfiber distance of the crushed fibers in the non-skin side portion of the absorbent core. Absorbent article. The absorbent article according to claim 1.
The total weight of the hardwood water-retaining fiber is the left side portion and the right side portion when the anterior side portion and the rear side portion when the longitudinal direction is bisected and the left side portion and the right side portion when the width direction is bisected. In both cases, the difference between the case of comparison and the case of comparing the skin side portion and the non-skin side portion when the thickness direction is bisected is within 10%.
The total weight of the softwood water-retaining fiber is the left side portion and the right side portion when the anterior side portion and the rear side portion when the longitudinal direction is bisected and the left side portion and the right side portion when the width direction is bisected. The difference is within 10% in both the case of comparison and the case of comparing the skin side portion and the non-skin side portion when the thickness direction is bisected. Absorbent article. The absorbent article according to any one of claims 1 to 7.
An absorbent article characterized in 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. The absorbent article according to any one of claims 1 to 7.
An absorbent article characterized in that 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. The absorbent article according to any one of claims 1 to 9.
The absorbent core is formed by laminating the crushed fibers.
The absorbent core has a hardwood layer in which the weight of the hardwood water-retaining fiber is heavier than the weight of the softwood water-retaining fiber, and a softwood layer in which the weight of the softwood water-retaining fiber is heavier than the weight of the softwood water-retaining fiber. And
The broad-leaved tree layer is provided on the skin side of the coniferous tree layer.
An absorbent article characterized in that the outer peripheral edge of the hardwood 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 10.
The absorbent article has a skin-side sheet made of fibers.
The skin-side sheet is provided adjacent to the skin side surface of the absorbent core.
At least a portion of the hardwood water-retaining fibers protrudes from the skin-side surface of the absorbent core and extends into the skin-side sheet.
An absorbent article characterized in that at least a part of the hardwood water-retaining fibers is in contact with the fibers of the adjacent skin-side sheet inside the skin-side sheet. The absorbent article according to any one of claims 1 to 10.
The absorbent core has synthetic fibers and
The synthetic fiber is contained more in the skin side portion than in the non-skin side portion of the absorbent core when it is bisected in the thickness direction.
An absorbent article characterized by having a portion in which the synthetic fibers are fused to each other in the skin side portion of the absorbent core. The absorbent article according to any one of claims 1 to 12.
The absorbent article comprises a cover sheet and
The cover sheet is joined to the absorbent core adjacent to the non-skin side of the absorbent core.
The back sheet is joined to the cover sheet adjacent to the non-skin side of the cover sheet.
On the non-skin side of the back sheet, a plurality of slip stoppers extending in the first direction are provided at intervals in the second direction orthogonal to the first direction.
An absorbent article characterized in that the minimum value of the interval in the second direction of the slip stopper is larger than the average fiber length of the water-retaining fiber made of the hardwood. The absorbent article according to claim 1 to 13.
The average fiber width of the hardwood water-retaining fiber is 15 μm or less.
The number of the hardwood water-retaining fibers contained per unit area of the absorbent core is 300 / mm2 or more and less than 2500 / mm2.
An absorbent article characterized by having a highly absorbent polymer between the plurality of hardwood water-retaining fibers. The absorbent article according to claim 1 to 14.
The standard deviation of the fiber length of the hardwood water-retaining fiber is 0.27 or less.
An absorbent article characterized in that the standard deviation of the fiber width of the hardwood water-retaining fiber is 7.55 or less. The absorbent article according to claim 15.
The value obtained by adding the standard deviation of the fiber length of the hardwood water-retaining fiber to the average fiber length of the hardwood water-retaining fiber is smaller than twice the value of the average fiber length of the hardwood water-retaining fiber.
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 larger than the value of 1/2 of the average fiber length of the hardwood water-retaining fiber. An absorbent article characterized by. The absorbent article according to claim 1 to 16.
The absorbent core contains a plurality of thermoplastic fibers and has a pressing portion for integrally pressing the absorbent core in the thickness direction.
An absorbent article characterized in that the thermoplastic fibers are fused to each other in the squeezed portion.

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