Manufacturing method of interlabial pad and interlabial pad

Abstract

To provide an interlabial pad with an absorbent core having good water solubility and shape stability.SOLUTION: A manufacturing method of interlabial pads includes: a defibration step (S201) of defibrating a pulp sheet containing hardwood pulp into crushed pulp; and an absorbent core forming step (S202) of accumulating the crushed pulp to form an absorbent core (132). The pulp sheet is defibrated in the defibration step such that, when the crushed pulp is subjected to a pulp crushed condition evaluation test in which the crushed pulp is passed through a plurality of types of sieves with different number of mesh sizes between 25.4 mm each, a ratio of the weight of fibers that do not pass through a 14-mesh or more sieve (312 to 314), to the total weight of the evaluation object crushed pulp is 10% or less and a ratio of the weight of fibers passing through a 60-mesh sieve (315) thereto is 20% or less.SELECTED DRAWING: Figure 18

Description

Technical Field

[0001] The present invention relates to a method for manufacturing an interlabial pad and an interlabial pad.

Background Art

[0002] Conventionally, absorbent articles such as interlabial pads that are worn in close contact with the labia have been known. In such interlabial pads (absorbent articles), a plurality of slits are provided in a member with high rigidity such as an absorber, so that it can be deformed three-dimensionally along the unevenness of the wearer's body, thereby improving the fit during wearing. For example, Patent Document 1 discloses an interlabial pad provided with a plurality of slits along the longitudinal direction and the short-side direction of the product.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In recent years, in such interlabial pads, by forming an absorbent core using pulp containing hardwood pulp with a short fiber length, the hydrolyzability of the absorbent core is enhanced, and when it is flushed into a toilet or the like after use, it dissolves in water and easily breaks apart. However, in the conventional manufacturing method, when defibrating pulp containing hardwood pulp, a large amount of large fiber lumps (knots) and overly fine fibers (fines) are included, making it difficult to manufacture an absorbent core that achieves both good hydrolyzability and shape stability.

[0005] The present invention has been made in view of the above problems, and an object thereof is to provide an interlabial pad provided with an absorbent core having good hydrolyzability and shape stability.

Means for Solving the Problems

[0006] The main invention for achieving the above object is a method for manufacturing an interlabial pad having an absorbent core, comprising a defibrillation step of defibrillating a pulp sheet containing hardwood pulp into pulverized pulp, and an absorbent core forming step of accumulating the pulverized pulp to form the absorbent core. When a pulp pulverization state evaluation test is performed on the pulverized pulp by passing it through a plurality of types of sieves having different mesh numbers at intervals of 25.4 mm, the ratio of the weight of fibers not passing through a sieve of 14 mesh or more is 10% or less with respect to the total weight of the pulverized pulp to be evaluated, and the ratio of the weight of fibers passing through a 60-mesh sieve is 20% or less with respect to the total weight of the pulverized pulp to be evaluated. The pulp sheet is defibrillated in the defibrillation step as described above. The method for manufacturing an interlabial pad is characterized by this. That is.

[0007] Other features of the present invention will be clarified by the description in this specification and the attached drawings.

Effect of the Invention

[0008] According to the present invention, it is possible to provide an interlabial pad having an absorbent core with good hydrolysis resistance and shape stability.

Brief Description of the Drawings

[0009]

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Best Mode for Carrying Out the Invention

[0010] From the description of this specification and the accompanying drawings, at least the following matters become clear. (Aspect 1) A method for manufacturing an interlabial pad having an absorbent core, comprising a defibrillation step of defibrillating a pulp sheet containing hardwood pulp into pulverized pulp, and an absorbent core forming step of accumulating the pulverized pulp to form the absorbent core. When a pulp pulverization state evaluation test is performed on the pulverized pulp by passing it through a plurality of types of sieves having different mesh numbers at 25.4 mm intervals, the ratio of the weight of fibers that do not pass through a sieve of 14 mesh or more is 10% or less with respect to the total weight of the pulverized pulp to be evaluated, and the ratio of the weight of fibers that pass through a 60-mesh sieve is 20% or less with respect to the total weight of the pulverized pulp to be evaluated. The method for manufacturing an interlabial pad is characterized in that the pulp sheet is defibrillated in the defibrillation step.

[0011] According to the method for manufacturing an interlabial pad of Aspect 1, since the ratio of large fiber lumps (NOTS) that do not pass through a sieve of 14 mesh or more is as low as 10% or less, it is easier to suppress the fiber lumps from remaining without disintegrating in water compared to the reverse case. Also, since the ratio of fine fibers (FINE) that pass through a 60-mesh sieve is as low as 20% or less, the fibers are more likely to entangle with each other and the shape of the absorbent core is more likely to be stably maintained compared to the reverse case. Therefore, an interlabial pad having an absorbent core that has a stable shape during wearing and is highly hydrolyzable and easily disintegrates when discarded in a toilet or the like after use can be manufactured. (Aspect 2) The method for manufacturing an interlabial pad according to Aspect 1, wherein in the defibrillation step, the defibrillation amount per unit width of the pulp sheet is 7.5 to 60.0 kg / mh.

[0012] According to the method for manufacturing the interlabial pad of Mode 2, when increasing the amount of fibrillation per unit time in the fibrillation step, the ratio of NOTS increases, and when decreasing the amount of fibrillation per unit time, the ratio of FINE may increase. However, by performing fibrillation so that the amount of fibrillation of the pulp fibers satisfies the condition of 7.5 to 60 kg / mh, it is possible to facilitate transfer to the base sheet while maintaining the shape of the absorbent core. (Mode 3) The method for manufacturing an interlabial pad according to any one of Modes 1 to 2, wherein in the fibrillation step, the pulp sheet is fibrillated using a garnet cylinder around which a saw blade is wound along the circumferential direction of the rotating roll.

[0013] According to the method for manufacturing the interlabial pad of Mode 3, by pulverizing the pulp sheet with a saw blade having a large number of fine blades, it is easier to form finer pulverized pulp compared to the case of performing fibrillation using a conventional sommill or hammer mill. In particular, in the pulverized pulp, since it is possible to reduce the ratio of NOTS, it is suitable for manufacturing an absorbent core with high hydrolyzability. (Mode 4) The method for manufacturing an interlabial pad according to any one of Modes 1 to 3, wherein the pulverized pulp does not contain fibers that do not pass through the sieve of 14 mesh or more when the pulp pulverization state evaluation test is performed.

[0014] According to the method for manufacturing the interlabial pad of Mode 4, since the absorbent core does not contain NOTS, it is difficult for a portion where the fiber density becomes locally high to occur, and the water absorption and water retention tend to be uniform. In addition, the hydrolyzability is improved, and the absorbent core is easily decomposed when flushed into the toilet. Therefore, it is possible to manufacture an absorbent core having good water absorption and water retention and hydrolyzability. (Mode 5) The method for manufacturing an interlabial pad according to any one of Modes 1 to 4, comprising a conveying step of conveying the absorbent core in a conveying direction, a slit forming step of forming a slit in the conveyed absorbent core, and a loosening step of loosening the pulverized pulp constituting the absorbent core.

[0015] According to the method for manufacturing an interlabial pad of Aspect 5, slits are formed in the absorbent core by the slit forming step. As a result, when the used interlabial pad is flushed down the toilet or the like, water is easily drawn into the inside of the absorbent core through the slits, and the pulp fibers are easily brought into contact with water. Further, by the loosening step, the pulp fibers are loosened, so that water is likely to permeate uniformly throughout the absorbent core. Therefore, an absorbent core having good hydrolysis can be manufactured. (Aspect 6) The loosening step is performed after the slit forming step, and is the method for manufacturing an interlabial pad according to any one of Aspects 1 to 5.

[0016] According to the method for manufacturing an interlabial pad of Aspect 6, each of the plurality of slits formed in the absorbent core in the slit forming step is likely to expand in the loosening step. As a result, when the used interlabial pad is flushed down the toilet or the like, water easily penetrates from the cut, and the water easily reaches the inside of the absorbent core. Therefore, the pulp fibers constituting the absorbent core are easily brought into contact with water, and the hydrolysis can be further enhanced. (Aspect 7) The loosening step is performed by sandwiching the interlabial pad between a first roller that rotates around a rotation axis along a direction orthogonal to the conveyance direction and a second roller that is provided adjacent to the downstream side of the first roller in the conveyance direction and rotates around a rotation axis along a direction orthogonal to the conveyance direction, and conveying it along the conveyance direction. In the vertical direction, the position of the portion of the circumferential surface of the first roller that contacts the interlabial pad on one side is located on one side rather than the position of the portion of the circumferential surface of the second roller that contacts the interlabial pad on the other side, and is the method for manufacturing an interlabial pad according to any one of Aspects 1 to 6.

[0017] According to the method for manufacturing an interlabial pad of Aspect 7, in the loosening step, while the interlabial pad is being conveyed in the conveying direction (MD direction), it is curved on one side and the other side in the thickness direction so as to wrap around the circumferential surfaces of rollers such as the first roller and the second roller. As a result, the slits provided in the absorbent core are widened or narrowed. This makes it easier for each of the plurality of slits to open. When the used interlabial pad is discarded in a toilet or the like, water is more likely to be drawn in through the opened slits, and the hydrolysis property of the absorbent core is further enhanced. (Aspect 8) The absorbent core has a front-back direction and a width direction, the length of the absorbent core in the front-back direction is longer than the length in the width direction, and in the loosening step, the absorbent core is conveyed with the front-back direction along the conveying direction. The method for manufacturing an interlabial pad according to any one of Aspects 1 to 7.

[0018] According to the method for manufacturing an interlabial pad of Aspect 8, by being conveyed in a state where the length in the MD direction is increased, the absorbent core is more likely to wrap around a wide range in the circumferential direction of the roller. That is, by wrapping the absorbent core around the circumferential surface of the roller as long as possible, it becomes easier to bend the absorbent core. Thereby, the slits can be made easier to open. (Aspect 9) The length of the absorbent core in the front-back direction is longer than twice the diameter of the first roller. The method for manufacturing an interlabial pad according to any one of Aspects 1 to 8.

[0019] According to the method for manufacturing an interlabial pad of Aspect 9, the absorbent core is more likely to wrap around a range nearly half in the circumferential direction of the roller. Therefore, the absorbent core is more likely to bend along the circumferential surface of each roller. Thereby, the slits are made easier to open, and the hydrolysis property can be further improved. (Aspect 10) The method for manufacturing an interlabial pad according to any one of Aspects 1 to 9 further includes a sealer step of folding the absorbent core in half along a folding line along the front-back direction, and the loosening step is performed after the sealer step.

[0020] According to the method for manufacturing an interlabial pad of Aspect 10, by loosening the absorbent core that has been folded in half and thickened in the sailor process in the loosening process, the slit can be more easily opened and the hydrolysis resistance can be further improved.

[0021] (Aspect 11) In the slit forming step, a plurality of first slits along the width direction and a plurality of second slits along the front-rear direction are formed, and the total length of the plurality of first slits is longer than the total length of the plurality of second slits. The method for manufacturing an interlabial pad according to any one of Aspects 1 to 10.

[0022] According to the method for manufacturing an interlabial pad of Aspect 11, by curving the absorbent core conveyed along the MD direction in the thickness direction, the first slit along the CD direction is more likely to open wider than the second slit along the MD direction. Therefore, if the total length of the first slits is longer than the total length of the second slits, the length at which the slits are likely to open as a whole becomes longer. Thereby, the hydrolysis resistance of the absorbent core can be improved.

[0023] (Aspect 12) An interlabial pad provided with an absorbent core having a pulverized pulp obtained by defibrating a pulp sheet containing hardwood pulp, wherein when a pulp pulverization state evaluation test is performed in which the pulverized pulp is passed through a plurality of types of sieves having different mesh numbers between 25.4 mm, the ratio of the weight of fibers that do not pass through a sieve of 14 mesh or more is 10% or less with respect to the total weight of the pulverized pulp to be evaluated, and the ratio of the weight of fibers that pass through a sieve of 60 mesh is 20% or less with respect to the total weight of the pulverized pulp to be evaluated. The interlabial pad is characterized by this.

[0024] (Aspect 12) According to the interlabial pad of Aspect 12, since the ratio of large fiber lumps (NOTS) that do not pass through a sieve of 14 mesh or more is as low as 10% or less, it is easier to suppress the fiber lumps from remaining without disintegrating in water compared to the reverse case. Also, since the ratio of fine fibers (FINE) that pass through a 60-mesh sieve is as low as 20% or less, the fibers are more likely to entangle with each other and the shape of the absorbent core is more likely to be stably maintained compared to the reverse case. Therefore, it is possible to realize an interlabial pad provided with an absorbent core that has a stable shape during wearing and is highly hydrolyzable and easily disintegrates when discarded in a toilet or the like after use. ===Embodiment=== Hereinafter, embodiments will be described by taking the interlabial pad 1 (hereinafter also referred to as "pad 1") as an example of the absorbent article according to the present invention. The interlabial pad is a sanitary product that is sandwiched between a woman's labia and absorbs excrement (body fluid) such as menstrual blood.

[0025] <Basic Configuration of Interlabial Pad 1> FIG. 1 is a plan view of pad 1 in a deployed state. FIG. 1 is a view seen from the skin side of pad 1. FIG. 2 is a schematic cross-sectional view taken along the line A-A of FIG. 1. FIGS. 3 and 4 are diagrams for explaining the configuration of pad 1. In each figure (FIGS. 1 to 4), C-C in the center indicates the center in the width direction, and CL in the center indicates the center in the front-rear direction of the absorbent layer 13 (described later) when pad 1 is viewed in the thickness direction. Also, FIGS. 1 and 2 are diagrams in a state where the finger insertion sheet 15 (described later) is cut along C-C and pad 1 is placed flat on a plane ("flat on a plane" state).

[0026] Pad 1 has a front-rear direction, a width direction, and a thickness direction that are orthogonal to each other. In the front-rear direction of pad 1, when worn, the side located on the ventral side of the wearer is defined as the "front side", and the side located on the dorsal side of the wearer is defined as the "rear side". Also, in the thickness direction of pad 1, the side that contacts the wearer's skin is defined as the "skin side", and the opposite side is defined as the "non-skin side".

[0027] As shown in FIGS. 1 to 4, the pad 1 has a substantially elliptical shape in plan view, with the length in the front-rear direction being longer than the length in the width direction, and is symmetric with respect to the center C-C in the width direction. In the front-rear direction, it is constricted inward in the width direction at the center CL, having a portion where the length in the width direction becomes narrower. Also, the pad 1 has an asymmetric shape in plan view with respect to the center in the front-rear direction. Specifically, the center CL (the center in the front-rear direction of the absorption layer 13) is located on the rear side of the center of the pad 1 in the front-rear direction, and the distance from the front end of the pad 1 to the front end of the absorption layer 13 is longer than the distance from the rear end of the pad 1 to the rear end of the absorption layer 13. That is, in the front-rear direction of the pad 1, the absorption layer 13 is disposed closer to the rear side. As shown in FIGS. 2 to 4, the pad 1 includes a surface layer 11, a sub-absorption layer 12, an absorption layer 13, a back layer 14, and a finger insertion sheet 15.

[0028] The pad 1 of the present embodiment is stored and distributed as a product folded to the non-skin side along the fold line F. FIGS. 3 and 4 are diagrams for explaining the state in which the pad 1 is disassembled into each member. As shown in FIG. 3A, the pad 1 of the present embodiment is folded toward the non-skin side along the fold line F (folding line) at the central portion (center C-C) in the width direction, and the finger insertion sheet 15 for forming the finger insertion portion 20 is fixed on the outermost non-skin side using an adhesive such as a hot melt adhesive HMA. The fold line F is a bent portion provided at the central portion in the width direction along the front-rear direction. The fold line F is a portion having a predetermined width, and the vertex on the skin side of the fold line F (the portion protruding most on the skin side) is substantially at the same position as the center C-C in the width direction. FIG. 3B shows the state in which the finger insertion sheet 15 is separated from the back layer 14, and FIG. 3C shows the state in which the pad 1 with the finger insertion sheet 15 removed is made horizontal from the folded state at the fold line F. Then, as shown in FIG. 4, from the state shown in FIG. 3C, the surface layer 11, the sub-absorption layer 12, the absorption layer 13, and the back layer 14 are stacked in order from the skin side in the thickness direction, and at least some of these members are joined by an adhesive or the like (see FIG. 2).

[0029] Since the surface layer 11 is located on the side closest to the skin and comes into contact with the wearer's skin (between the labia) during wearing, it is preferable to use a soft sheet that is less likely to irritate the skin. The surface layer 11 forms the outer shape of the pad 1 and is a liquid-permeable sheet member. As the surface layer 11, for example, non-woven fabrics obtained from manufacturing methods such as meltblown, spunbond, pointbond, through-air, needle punch, dry / wet spunlace, and foam film can be used alone or in combination. Materials made of rayon, acetate, cotton, pulp, or synthetic resin (e.g., polyethylene terephthalate: PET, polypropylene: PP, polyethylene: PE, etc.) can be used alone or in combination as composite materials forming a core-sheath structure, or a sheet member of fibers that are mixed can be used. The pad 1 of the present embodiment uses a sheet member made of rayon and polyethylene terephthalate.

[0030] The secondary absorption layer 12 is located on the non-skin side of the surface layer 11 and on the skin side of the absorption layer 13. The secondary absorption layer 12 serves as a cushion layer that flexibly follows changes such as the wearer's movement, changes in the behavior of the labia, and pressure from clothing between the surface layer 11 and the absorption layer 13, changes its own shape, and reduces the discomfort given to the wearer. The shape of the secondary absorption layer 12 is approximately elliptical, smaller than the surface layer 11, and is located at the approximate center (more precisely, closer to the rear side) of the pad 1. Also, at the center CL in the front-rear direction of the secondary absorption layer 12, it is constricted inward in the width direction, and the length in the width direction is narrowed. As the secondary absorption layer 12, for example, pulp, chemical pulp, rayon, acetate, natural cotton, and synthetic fibers can be used alone or in combination. In the present embodiment, fibers mainly mixed with pulp fibers, rayon fibers, and polyethylene terephthalate (PET) are used.

[0031] The absorption layer 13 is located on the non-skin side of the secondary absorption layer 12 and on the skin side of the back layer 14, and is an absorber that absorbs body fluids such as excrement. The absorption layer 13 has an approximately elliptical shape and is located at the approximate center (more precisely, closer to the rear side) of the pad 1. Details of the absorption layer 13 will be described later.

[0032] The back surface layer 14 is a sheet member located on the non-skin side of the absorption layer 13. The back surface layer 14 forms the outer shape of the pad 1 and has substantially the same shape and size as the front surface layer 11 in plan view. As the back surface layer 14, a sheet member such as a liquid-permeable sheet or a liquid-impermeable sheet can be used. For example, a sheet-like film of synthetic resin, a breathable film, pulp, paper, non-woven fabric, a breathable liquid-blocking sheet, or a sheet member combining these can be used. In this embodiment, a sheet-like member mixed with rayon, polyethylene terephthalate (PET), and pulp is used.

[0033] The finger insertion sheet 15 is a sheet member for forming the finger insertion portion 20. The finger insertion portion 20 is a space between the finger insertion sheet 15 and the back surface layer 14 and is a space for the wearer to insert a finger when wearing the pad 1. The finger insertion sheet 15 is shorter in length in the front-back direction than the back surface layer 14 and shorter in length in the width direction than the back surface layer 14. Also, it is provided on the non-skin side of the back surface layer 14 and on the rear side in the front-back direction. Both side portions in the width direction of the finger insertion sheet 15 are joined and fixed to the non-skin side of the back surface layer 14 by a finger insertion sheet joint portion 16 formed by an adhesive such as a hot melt adhesive (see FIG. 2). The front end portion of the finger insertion sheet 15 and the rear end portion of the finger insertion sheet 15 each have an opening where the finger insertion sheet 15 and the back surface layer 14 are not fixed by an adhesive. The front opening is larger than the rear opening. The wearer can insert a finger (for example, the middle finger) through the front opening of the finger insertion portion 20, abut the pad 1 against the labia majora in a state of supporting the pad 1, and wear it.

[0034] As the finger insertion sheet 15, the same materials as those of the surface layer 11 and the back surface layer 14 can be used. For example, spunlace nonwoven fabrics, shrink-type nonwoven fabrics, stretchable spunbonds, etc. made of composite synthetic fibers such as PE / PP, PE / PET, PP / PP as raw materials, or sheet members made of fibers of rayon, acetate, cotton, pulp, or synthetic resin (e.g., polyethylene terephthalate: PET), or sheet members such as breathable films, paper, air-permeable liquid-blocking sheets, etc. can be used. Also, for example, sheets having elasticity such as films made of synthetic rubber or amorphous olefin-based resins, open-cell foam films, nets, woven fabrics, or fabrics in which spun filaments made of synthetic rubber are woven into woven fabrics, spunbond nonwoven fabrics or meltblown nonwoven fabrics mainly composed of synthetic rubber, and foamed foam sheets may be used. In the present embodiment, a sheet member mainly composed of pulp and rayon is used.

[0035] Note that although the pad 1 of the present embodiment is folded to the non-skin side along the fold line F in the unused state, it is not limited to this. For example, in the unused state, it may not have a fold line F and may not be folded, and the wearer may fold it to the non-skin side by himself / herself when wearing. Also, it may have a plurality of fold lines F. The fold line F may have a so-called crease that is folded, or may not have a crease.

[0036] <Regarding the wearing of the pad 1> The pad 1 is worn by being brought into contact with the skin (excretion port) of the wearer in a state of being folded toward the non-skin side along the front-rear direction at the central portion in the width direction. The pad 1 of the present embodiment is a sanitary product, and can be worn by folding it toward the non-skin side so as to be convex in the skin direction along the fold line F and sandwiching the central portion in the width direction of the pad 1 between the labia of a woman. Since the pad 1 has a higher adhesion to the body (excretion port) than a sanitary napkin, leakage of excrement (menstrual blood) is less likely to occur, and discomfort during excretion is less likely to be caused.

[0037] When wearing, the user can be in a wearing state by inserting a finger (index finger or middle finger) into the finger insertion part 20 from the front side of the pad 1 bent at the folding part F, bringing the pad 1 into contact with and sandwiching it between the labia from the ventral side. After use, the pad 1 in the wearing state can be dropped into the toilet or picked up by hand and put into the toilet and flushed for disposal. In order to be flushed down the toilet, it is preferable that each member and the adhesive constituting the pad 1 are made of a biodegradable material, a water-dispersible material, or a water-soluble material. By flushing it down the toilet, the labor of treating the pad 1 as garbage can be reduced, and the amount of garbage can also be reduced.

[0038] Note that "biodegradable" means that in the presence of bacteria such as actinomycetes and other microorganisms, the substance is decomposed into gases such as carbon dioxide or methane, water, and biomass under anaerobic or aerobic conditions according to the processes of nature, and the biodegradability (biodegradation rate, degree of biodegradation, etc.) of the substance is comparable to that of materials occurring naturally such as fallen leaves or synthetic polymers generally recognized as biodegradable in the same environment. "Water-dispersible" also means "hydrolyzable". Although it is not affected by a limited amount of moisture (menstrual blood) during wearing, in a large amount of water or water flow, the fibers are easily dispersed into small pieces to such an extent that they do not clog at least the general toilet pipes. "Water-soluble" means that although it is not affected by a limited amount of moisture (menstrual blood) during wearing, it has the property of dissolving in a large amount of water or water flow.

[0039] <Regarding the absorption layer 13> FIG. 5 is a plan view for explaining the configuration of the absorption layer 13. The absorption layer 13 of the present embodiment includes a skin-side sheet 131, an absorbent core 132, and a non-skin-side sheet 133 in order from the skin side in the thickness direction. Also, as shown in FIG. 5, the region located at the center when the pad 1 is trisected in the width direction is defined as the central region CR, and the regions located on both sides are defined as the end regions SR.

[0040] The absorbent core 132 is a part having water absorption and water retention properties for absorbing and holding liquids (body fluids) such as menstrual blood, and for example, pulp, chemical pulp, rayon, acetate, natural cotton, synthetic fibers, cellulose foam, continuous foam of synthetic resin, etc. can be used alone or in combination. Further, a particulate polymer absorbent or a fibrous polymer absorbent may be mixed, or a sheet-like polymer absorbent may be used. Furthermore, in order to maintain the bulkiness of the absorbent core and enhance water retention, crosslinked and curled chemical pulp, acetate, and synthetic fibers may be mixed with a crosslinking agent. In the pad 1, pulp fibers (water-absorbent fibers) formed into a predetermined shape are used.

[0041] The skin-side sheet 131 is a member that covers the absorbent core 132 from the skin side, and the non-skin-side sheet 133 is a member that covers the absorbent core 132 from the non-skin side. Examples of the skin-side sheet 131 and the non-skin-side sheet 133 include cellulose such as ground pulp and cotton, regenerated cellulose such as rayon and fibrillated rayon, semi-synthetic cellulose such as acetate and triacetate, and those obtained by subjecting thermoplastic hydrophobic chemical fibers to a hydrophilic treatment. In the present embodiment, the skin-side sheet 131 of the pad 1 is a sheet made of a span lace of pulp and rayon, and the non-skin-side sheet 133 is a sheet made of pulp such as a wet-laid tissue of 100% pulp.

[0042] Also, by providing the skin-side sheet 131, the excrement that has reached the absorption layer 13 is easily diffused in the horizontal direction, and the horizontally spread excrement can be absorbed by the absorbent core 132. As a result, the excrement can be quickly absorbed by the absorbent core 132, so that it is easy to reduce the discomfort given to the skin of the wearer.

[0043] In addition, the absorbent layer 13 is provided with a plurality of slits 18, 18... and a plurality of squeezing portions 19, 19... (not shown in FIG. 5). The slit 18 is at least a cut that penetrates the absorbent layer 13 (the skin-side sheet 131, the absorbent core 132, and the non-skin-side sheet 133) in the thickness direction. However, the slit 18 may penetrate the absorbent layer 13 and the sub-absorbent layer 12 in the thickness direction. By providing the slit 18, when the pad 1 is worn, the absorbent layer 13 and the sub-absorbent layer 12 can easily deform flexibly following the movement of the wearer's body, and the fit is improved. In addition, by diffusing the absorbed excreted liquid in the front-rear direction and the left-right direction along the slit 18, the excreted liquid can be absorbed and held in a wide range of the absorbent core 132. Although details will be described later, the slit 18 is formed by making a cut with a cutter or the like from the non-skin side in the thickness direction of the absorbent layer 13. Therefore, in the pad 1 of the present embodiment, at least a slit (cut) is formed in the non-skin-side sheet 133.

[0044] The slit 18 has a first slit 18a along the width direction and a second slit 18b along the front-rear direction. Here, the "slit along the width direction" refers to a slit in which the smaller of the angles formed by the slit (or the tangent of the slit) and the width direction is 45 degrees or less. That is, the first slit 18a includes a slit provided parallel to the width direction and a slit provided inclined by a predetermined angle of 45 degrees or less with respect to the width direction. Similarly, the "slit along the front-rear direction" refers to a slit in which the smaller of the angles formed by the slit (or the tangent of the slit) and the front-rear direction is less than 45 degrees. That is, the second slit 18b includes a slit provided parallel to the front-rear direction and a slit provided inclined by a predetermined angle of less than 45 degrees with respect to the front-rear direction.

[0045] The squeezing part 19 is a part that squeezes the absorption layer 13 (the skin-side sheet 131, the absorbent core 132, and the non-skin-side sheet 133) and the sub-absorption layer 12 in the thickness direction. For example, the absorption layer 13 and the sub-absorption layer 12 are overlapped in the thickness direction and embossing or the like is performed to form it (see Fig. 4). By providing the squeezing part 19, a plurality of fibers constituting the absorption layer 13 and the sub-absorption layer 12 are crimped, and the absorption layer 13 and the sub-absorption layer 12 are each likely to maintain their shapes and are less likely to come apart. Therefore, when the pad 1 is worn and the wearer moves the body, it is possible to suppress the absorption layer 13 from losing its shape or being twisted, resulting in deterioration of the fit or leakage of excreted liquid.

[0046] Note that the absorption layer 13 and the sub-absorption layer 12 are only crimped by the squeezing part 19 and are not fixed using an adhesive or the like. Therefore, when the used pad 1 is flushed down the toilet, if the squeezing part 19 gets wet with water, the crimping (hydrogen bonding) between the fibers is released, and the fibers constituting the absorption layer 13 and the sub-absorption layer 12 are likely to come apart. As a result, the hydrolyzability (water dispersibility) is increased, and it is possible to avoid problems such as clogging of the toilet pipes.

[0047] Further, the absorbent core 132 of the present embodiment contains softwood absorbent fibers (softwood pulp), which are absorbent fibers made of softwood, as pulp fibers (absorbent fibers). This softwood absorbent fiber has the characteristics of having a shorter fiber length and a thinner fiber diameter compared to coniferous tree absorbent fibers (coniferous tree pulp) made of coniferous trees.

[0048] Fig. 6 is a diagram showing the fiber length distribution of softwood absorbent fibers (softwood pulp) and coniferous tree absorbent fibers (coniferous tree pulp). The horizontal axis represents the fiber length (mm), and the vertical axis represents the frequency (%). As shown in Fig. 6, the average fiber length of the coniferous tree pulp is about 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). In contrast, the average fiber length of the softwood absorbent fiber is about 0.79 mm, and the distribution width of the fiber length is narrow (the standard deviation is 0.27).

[0049] The average fiber length of pulp fibers means the length-weighted average fiber length L(l) measured by the centerline fiber length (Cont). The length-weighted average fiber length is measured as the L(l) value by the kajaaniFiberLab fiber properties (off-line) manufactured by Metso Automation. This is also the method recommended in JIS P 8226-2 (Pulp - Fiber length measurement method by optical automatic analysis method - Conforming to the non-polarization method).

[0050] The absorbent core 132 has high water retention because it is composed of water-absorbent fibers with a short fiber length such as hardwood pulp (water-absorbent fibers with an average fiber length of about 0.8 mm). For example, when comparing an absorber formed of hardwood pulp with a short fiber length and an absorber formed of softwood pulp with a long fiber length at the same weight, the fiber number density of the hardwood pulp is greater than that of the softwood pulp. That is, by using hardwood pulp, it is possible to increase the density of the absorbent core 132 compared to the case of using softwood pulp. And by increasing the density of the absorbent core 132, the capillary effect can be enhanced and the water retention can be improved. 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 the closest packing structure using the fiber thickness + average fiber distance.

[0051] <Method for manufacturing the interlabial pad 1> Next, the method for manufacturing the interlabial pad 1 will be described. FIG. 7 is a flowchart showing the manufacturing process of the pad 1 according to the present embodiment. FIG. 8 is a schematic diagram for explaining a manufacturing apparatus 500 for manufacturing absorbent articles such as the pad 1. Note that FIGS. 7 and 8 illustrate typical processes related to the manufacture of the pad 1 and do not represent all of the manufacturing processes.

[0052] The manufacturing apparatus 500 shown in Fig. 8 can intermittently manufacture the pad 1 and other absorbent articles according to this embodiment by sequentially performing each process (S101 to S110) shown in Fig. 7. The manufacturing apparatus 500 includes a conveyance mechanism 510, an absorbent core laminating mechanism 520, a sub-absorbent layer laminating mechanism 530, an inversion mechanism 540, a first slit forming mechanism 550, a second slit forming mechanism 560, a cutting and sealing mechanism 570, a sealer mechanism 580, a finger insertion sheet attaching mechanism 590, and a loosening mechanism 595.

[0053] In the manufacturing process of the pad 1, first, a conveyance process is performed in which a continuum of the non-skin-side sheet 133 constituting the absorbent layer 13 is conveyed in the conveyance direction (S101). In the manufacturing apparatus 500, the conveyance direction is a direction along the front-rear direction of the pad 1. Hereinafter, the conveyance direction is also referred to as the "MD direction (Machine Direction)", and the direction orthogonal to the conveyance direction (the direction along the width direction of the pad 1 and the depth direction of the paper surface in Fig. 8) is also referred to as the "CD direction (Cross Direction)".

[0054] In the conveyance process, the non-skin-side sheet continuum 133a (base material sheet) in a state where the non-skin-side sheets 133 are connected in the MD direction is fed out from the original roll, and then is conveyed from the upstream side to the downstream side in the MD direction at a predetermined conveyance speed by the conveyance mechanism 510 including conveyance rollers and the like. While the non-skin-side sheet continuum 133a is being conveyed, each process of S102 to S110 is performed, thereby manufacturing the pad 1.

[0055] Next, an absorbent core laminating process is performed in which the absorbent core 132 is laminated on the non-skin-side sheet continuum 133a (base material sheet) conveyed in the MD direction using the absorbent core laminating mechanism 520 (S102). The absorbent core laminating mechanism 520 includes a defibrator 521, a material supply unit 522, and a rotating drum 523.

[0056] FIG. 9 is a flowchart showing the operations (steps) specifically performed in the absorbent core laminating step (S102). In the absorbent core laminating step, first, a defibering step is performed to defiber the pulp sheet into ground pulp that serves as the raw material for the absorbent core 132 (S201). The ground pulp is produced by defibering the pulp sheet PS1 with a defibering device 521. The defibering device 521 is provided with a garnet cylinder 521m. In this embodiment, the pulp sheet PS1 serving as the raw material for forming the absorbent core 132 is mainly composed of pulp containing hardwood pulp as described above, but may contain softwood pulp or may be a pulp-mixed spunlace.

[0057] FIGS. 10A to 10C are diagrams for explaining the configuration of the garnet cylinder 521m. FIG. 11 is a diagram for explaining a method of defibering the pulp sheet PS1 using the garnet cylinder 521m. The garnet cylinder 521m is a columnar rotating body that can rotate about a rotation axis 521Ar. In FIG. 10A, the rotation axis 521Ar is arranged along the CD direction, and the garnet cylinder 521m rotates counterclockwise about the rotation axis 521Ar. A plurality of saw blades 525, 525,... are provided on the circumferential surface 521mf of the garnet cylinder 521m. As shown in FIG. 9B, the saw blade 525 is a belt-shaped cutting tool in which fine blades are arranged along a predetermined direction (MD direction in FIG. 10B). In the garnet cylinder 521m, the saw blade 525 is provided so as to be wound in a helical shape in the circumferential direction of the circumferential surface 521mf. In this embodiment, the saw blades 525 are arranged at a pitch of about 5 mm along the CD direction of the circumferential surface 521mf as shown in FIG. 10C.

[0058] For example, in the saw blade 525 of the present embodiment, blades with a thickness of 0.8 mm and a height of 7 mm are provided in a plurality at a pitch of about 12.7 mm in the MD direction (see FIG. 10B), and the saw blade 525 is attached along the CD direction of the circumferential surface 521mf of the garnet cylinder 521m at a pitch of about 5 mm (see FIG. 10C). And in the state where the saw blade 525 is attached, the outer diameter of the garnet cylinder 521m (the diameter of the garnet cylinder 521m including up to the blade tip of the saw blade 525) is about 450 mm to 500 mm. However, the above dimensions are only examples and can be appropriately changed according to conditions such as the configuration of the defibrator 521 and the arrangement space.

[0059] When defibrating, the garnet cylinder 521m is rotated so as to scrape the surface of the pulp sheet PS1 fed out from the original roll with the saw blade 525, whereby the pulp sheet PS1 is finely pulverized and pulverized pulp is produced. In the present embodiment, defibration is performed using a feed roll 526 arranged so as to face the garnet cylinder 521m in the MD direction as shown in FIG. 11. The feed roll 526 is, for example, a rotating body that can rotate while supporting the pulp sheet PS1 on its circumferential surface by a nip mechanism (not shown) or the like.

[0060] In FIG. 11, the clearance (the distance in the MD direction) between the circumferential surface of the feed roll 526 and the blade tip of the saw blade 525 provided on the garnet cylinder 521m is adjusted to be, for example, about 0.5 mm. Then, the feed roll 526 is rotated while supporting the pulp sheet PS1, and the pulp sheet PS1 is fed toward the garnet cylinder 521m side while the garnet cylinder 521m is rotated at a predetermined speed in the direction opposite to the feed roll 526. Then, the pulp sheet PS1 is defibrated at the location where the circumferential surface of the feed roll 526 and the blade tip of the garnet cylinder 521m (saw blade 525) are closest to each other, and pulverized pulp is produced.

[0061] Using the garnet cylinder 521m of the present embodiment, the amount of pulp sheet PS1 with a unit width pulverized per unit time is 7.5 to 60 kg / hr, preferably 9.0 to 55 kg / hr. For example, when the maximum pulverization amount per unit time is 60 kg / hr, the diameter d including the cutting edge of the saw blade 525 of the garnet cylinder 521m is 470 mm, the rotation speed is 2000 rpm, and the feed amount of the pulp sheet P1 (width 525 mm in the CD direction) in the MD direction is 2.66 m / min, when the garnet cylinder 521m rotates once (= 3.14d), if the distance (lead) that the helically wound saw blade 525 advances in the axial direction is 20 mm, each blade of the saw blade 525 described above will shave the pulp sheet P1 by 0.0114 mm each time in the MD direction (the feed direction of the pulp sheet P1). By pulverizing the pulp sheet P1 finely in this way, it becomes possible to manufacture a pulverized pulp of an appropriate size that does not contain fiber lumps (NOTS) described later.

[0062] Next, referring back to FIG. 9, an absorbent core forming step (S202) of forming the absorbent core 132 using the pulverized pulp as a material, and a transfer step (S203) of transferring the formed absorbent core 132 to a base sheet (here, the non-skin side sheet continuum 133a) conveyed in the MD direction are performed. In the present embodiment, the absorbent core forming step (S202) and the transfer step (S203) are performed using the rotary drum 523.

[0063] The pulp pulverized by the garnet cylinder 521m is collected inside the material supply unit 522 disposed below the defibrator 521 and supplied to the rotary drum 523. The material supply unit 522 is disposed so as to cover the upper part of the rotary drum 523, mixes a thermoplastic resin with the pulverized pulp, and further mixes highly absorbent polymer particles (SAP) if necessary, and supplies the mixture to the rotary drum 523 by air conveyance.

[0064] The rotary drum 523 is a hollow cylindrical drum and is provided with a suction mechanism (not shown) that sucks air from the outside to the inside of the outer peripheral surface. Further, a plurality of recesses 523r are formed at a predetermined pitch on the outer peripheral surface as a mold for packing the material of the absorbent core 132. When the rotary drum 523 rotates and the recess 523r enters the material supply section 522, the material (pulverized pulp) of the absorbent core 132 supplied from the material supply section 522 accumulates (collects) in the recess 523r due to the suction of the suction mechanism. Thereby, the absorbent core 132 is formed (S202).

[0065] Then, when the rotary drum 523 rotates and the recess 523r containing the material of the absorbent core 132 reaches the lowermost part of the drum, the material of the absorbent core 132 comes off from the recess 523r and is transferred onto the base material sheet (non-skin side sheet continuum 133a) to be conveyed, and is delivered to the next process. Thereby, the absorbent core 132 is laminated on the skin side of the non-skin side sheet 133 (S103).

[0066] Next, returning to FIG. 7, the base material sheet on which the absorbent core 132 is laminated is overlapped with the continuum 131a of the skin side sheet 131 (see FIG. 8) in the process of being conveyed to the downstream side in the conveyance direction (MD direction) from the absorbent core lamination mechanism 520, and reaches the sub-absorbent layer lamination mechanism 530 in a state where the absorbent layer 13 is formed. For the sake of simplicity of explanation, the skin side sheet 131 is not shown in the following processes of FIG. 8.

[0067] Next, a sub-absorbing layer laminating step is performed (S103) in which the sub-absorbing layer 12 is laminated on the skin side in the thickness direction of the absorbing layer 13 by the sub-absorbing layer laminating mechanism 530. The sub-absorbing layer laminating mechanism 530 has a fibrillation device 531. The fibrillation device 531 has a garnet cylinder 531m which is a rotating body with a thin saw blade spirally wound around the circumferential surface of a cylindrical roll, similar to the garnet cylinder 521m described in FIG. 10 and the like. Then, in substantially the same manner as the fibrillation device 521, the pulp sheet PS2 fed out from the raw roll is rotated so as to shave it, thereby pulverizing the pulp sheet PS2 to produce pulverized pulp which becomes the raw material of the sub-absorbing layer 12. The pulverized pulp is directly sprayed onto the base sheet, and a layer of pulverized pulp (sub-absorbing layer 12) is laminated on the skin side of the absorbing layer 13.

[0068] The pulp sheet PS2 used in the sub-absorbing layer laminating step is composed of softwood pulp, and may contain hardwood pulp or may be a rayon blend. And the content rate of hardwood pulp in the pulp sheet PS2 is smaller than the content rate of hardwood pulp in the pulp sheet PS1. Thereby, the sub-absorbing layer 12 has a longer average fiber length and a thicker average fiber diameter than the absorbent core 132.

[0069] Also, after the sub-absorbing layer 12 is laminated on the absorbing layer 13, embossing is performed to form the squeezing portion 19. Thereby, a plurality of fibers constituting the absorbing layer 13 and the sub-absorbing layer 12 are crimped, so that they are less likely to be easily peeled off or lose their shape in the laminated state.

[0070] Next, an inversion step is performed (S104) in which the base sheet (absorbing layer 13 and sub-absorbing layer 12) is inverted in the thickness direction by the inversion mechanism 540. In FIG. 8, the base sheet that has been conveyed from the left side to the right side of the paper surface is inverted in the conveying direction from the right side to the left side, and at the same time, the thickness direction is also inverted. Therefore, after the inversion step, it is conveyed in the MD direction with the absorbing layer 13 laminated on the upper side in the vertical direction of the sub-absorbing layer 12.

[0071] Next, a first slit forming step of forming a first slit 18a in the absorption layer 13 using the first slit forming mechanism 550 is performed (S105). The first slit forming mechanism 550 includes a cutter roll 551 and an anvil roll 552. The cutter roll 551 is a rotating body provided with a plurality of blades on the circumferential surface of a cylindrical roll and driven to rotate about a rotation axis along the CD direction. The anvil roll 552 is a rotating body arranged to face the cutter roll 551 in the thickness direction (vertical direction in FIG. 8) and driven to rotate about a rotation axis along the CD direction. In the present embodiment, as shown in FIG. 8, the cutter roll 551 is provided on the upper side (non-skin side of the pad 1) in the vertical direction of the manufacturing apparatus 500, and the anvil roll 552 is provided on the lower side (skin side of the pad 1). Then, the first slit 18a is formed by sandwiching and pressing the base material sheet (absorption layer 13 and sub-absorption layer 12) in the thickness direction between the cutter roll 551 and the anvil roll 552.

[0072] FIGS. 12A to 12C are diagrams for explaining the configuration of the cutter roll 551 used when forming the first slit 18a. FIG. 12A is a plan view when the cutter roll 551 is viewed from the MD direction. FIG. 12B is a diagram showing the arrangement pattern of a plurality of blades 551c provided on the circumferential surface 551f of the cutter roll 551. FIG. 12C is a cross-sectional view taken along the D-D arrow in FIG. 12B. FIGS. 13A to 13B are diagrams for explaining the configuration of the anvil roll 552 used when forming the first slit 18a. FIG. 13A is a plan view when the anvil roll 552 is viewed from the MD direction. FIG. 13B is an enlarged view of the region E in FIG. 13A.

[0073] As shown in Fig. 12A, the cutter roll 551 of the first slit forming mechanism 550 is a cylindrical rotating body that rotates about a rotation axis Ar1 along the CD direction, and has a plurality of blades 551c, 551c... protruding radially outward from the circumferential surface 551f of the cylinder. The plurality of blades 551c are arranged in the pattern shown in Fig. 12B, and the pattern in Fig. 12B is intermittently provided at a predetermined pitch along the circumferential direction on the circumferential surface 551f of the cutter roll 551 as shown in Fig. 12A. Each of the plurality of blades 551c is provided so as to be able to form a slit mainly along the CD direction (the width direction of the pad 1). That is, each blade 551c of the cutter roll 551 is provided mainly parallel to the CD direction or inclined by a predetermined angle of 45 degrees or less with respect to the CD direction. With such blades 551c, a plurality of first slits 18a can be formed in the pad 1. However, the cutter roll 551 may form a slit 18 partially along the MD direction.

[0074] As shown in Fig. 13A, the anvil roll 552 of the first slit forming mechanism 550 is a cylindrical rotating body that rotates about a rotation axis Ar2 along the CD direction, and is provided so as to face the cutter roll 551 with the pad 1 (base material sheet) interposed therebetween (see Fig. 8). Then, while the anvil roll 552 and the cutter roll 551 are rotating, at the portion where the circumferential surface 552f of the anvil roll 552 and the tip of the blade 551c of the cutter roll 551 are in contact, a slit (cut) corresponding to the shape of the blade 551c is formed in the base material sheet (the absorption layer 13, the sub-absorption layer 12, etc. in this embodiment) sandwiched between the two.

[0075] In addition, a groove 552d recessed radially inward is provided in a part of the circumferential surface 552f of the anvil roll 552. In this embodiment, a pair of grooves 552d are provided on both sides of the central position CDCL of the anvil roll 552 in the CD direction. Further, the groove 552d is continuously provided along the circumferential direction (the direction corresponding to the MD direction) of the anvil roll 552.

[0076] FIG. 14 is a diagram for explaining the operation of forming the first slit 18a by the cutter roll 551 and the anvil roll 552. In FIG. 14, the positional relationship between the blade 551c of the cutter roll 551 and the groove 552d of the anvil roll 552 when the cutter roll 551 and the anvil roll 552 are aligned and opposed at the central position CDCL in the CD direction is shown.

[0077] As shown in FIG. 14, in the CD direction, on both sides of the central position CDCL, there is a portion where the blade 551c and the groove 552d overlap. For example, in the region F of FIG. 14, the first portion np located at the central portion of the blade 551c of the cutter roll 551 in the CD direction overlaps with the groove 552d of the anvil roll 552. On the other hand, the second portion cp located at both ends of the blade 551c in the CD direction does not overlap with the groove 552d. That is, when the tip of the blade 551c of the cutter roll 551 contacts the peripheral surface 552f of the anvil roll 552, the second portion cp of the blade 551c contacts the peripheral surface 552f, but the first portion np does not contact the peripheral surface 552f.

[0078] In this case, the second portion cp located at both ends of the blade 551c in the CD direction forms the slit 18 by pressing the base material sheet (such as the absorbent layer 13) toward the peripheral surface 552f of the anvil roll 552. On the other hand, the first portion np located at the central portion of the blade 551c in the CD direction does not form the slit 18 because it presses the base material sheet (such as the absorbent layer 13) toward the groove 552d of the anvil roll 552. As a result, in the first slit 18a along the width direction, a slit 18 is formed in such a way that the central portion in the CD direction (width direction) is divided (see the end region SR in FIG. 5).

[0079] In addition, in the anvil roll 552, it is preferable that the boundary between the circumferential surface 552f and the groove 552d is chamfered. In FIG. 13B, at the boundary between the circumferential surface 552f and the groove 552d of the anvil roll 552, the corner portion ch shown in black is chamfered. By providing such a chamfered portion ch, among the blades 551c of the cutter roll 551, at the boundary between the portion overlapping the circumferential surface 552f of the anvil roll 552 in the CD direction (the second portion cp forming the slit 18) and the portion overlapping the groove 552d (the first portion np not forming the slit 18), the way the force is applied when being pressed by the blade 551c changes gently. Therefore, compared with the case where there is no chamfered portion ch, it becomes difficult for the base material to adhere to the blade 551c at the end of the slit 18. Further, the chamfering at the boundary between the circumferential surface 552f and the groove 552d may be formed linearly as shown in FIG. 13B, or may be formed curvilinearly. That is, the boundary between the circumferential surface 552f and the groove 552d may have a curved surface shape.

[0080] Next, a second slit forming step of forming a second slit 18b in the absorption layer 13 is performed using the second slit forming mechanism 560 (S106). The second slit forming mechanism 560 has a cutter roll 561 and an anvil roll 562. The cutter roll 561 is a rotating body provided with a plurality of blades on the circumferential surface of a columnar roll and driven to rotate about a rotation axis along the CD direction. The anvil roll 562 is arranged to face the cutter roll 561 in the thickness direction (vertical direction in FIG. 8) and is a rotating body driven to rotate about a rotation axis along the CD direction. Further, in the second slit forming step, the second slit forming mechanism 560 cuts the base material sheet (absorption layer 13 and sub-absorption layer 12) into a substantially elliptical shape as shown by the broken line in FIG. 1.

[0081] Figs. 15A to 15C are diagrams for explaining the configuration of the cutter roll 561 used when forming the second slit 18b. Fig. 15A is a plan view when the cutter roll 561 is viewed from the MD direction. Fig. 15B is a diagram showing the arrangement pattern of a plurality of blades 561c provided on the circumferential surface 561f of the cutter roll 561. Fig. 15C is a cross-sectional view taken along the line G-G in Fig. 15B.

[0082] As shown in Fig. 15A, the cutter roll 561 of the second slit forming mechanism 560 is a cylindrical rotating body that rotates about a rotation axis Ar3 along the CD direction, and has a plurality of blades 561c, 561c... protruding radially outward from the circumferential surface 561f of the cylinder. The plurality of blades 561c are arranged in the pattern shown in Fig. 15B, and the pattern in Fig. 15B is intermittently provided at a predetermined pitch along the circumferential direction on the circumferential surface 561f of the cutter roll 561 as shown in Fig. 15A. Each of the plurality of blades 561c is provided so as to be able to form a slit mainly along the MD direction (the front-rear direction of the pad 1). That is, the blades 561c of the cutter roll 561 are provided mainly parallel to the MD direction or inclined by a predetermined angle of less than 45 degrees with respect to the MD direction. With such blades 561c, a plurality of second slits 18b can be formed in the pad 1. However, a slit 18 along a part of the CD direction may be formed by the cutter roll 561.

[0083] In addition, a circumferential blade 561rc is provided on the circumferential surface 561f of the cutter roll 561 so as to surround a plurality of blades 561c, 561c... along the MD direction. The circumferential blade 561rc is provided in accordance with the shape of the outer edge of the sub-absorbing layer 12 (a substantially elliptical shape shown by the broken line in Fig. 1), and the sheet-like sub-absorbing layer 12 laminated in the sub-absorbing layer lamination step (S103) is cut out like so-called die cutting to form the sub-absorbing layer 12 into a substantially elliptical shape.

[0084] The anvil roll 562 of the second slit forming mechanism 560 is a cylindrical rotating body that rotates about a rotation axis along the CD direction, and is provided so as to face the cutter roll 561 with the pad 1 (base material sheet) interposed therebetween (see FIG. 8). Note that no recess (groove) corresponding to the groove 552d (see FIG. 13) of the anvil roll 552 is provided on the circumferential surface of the anvil roll 562. Then, while the anvil roll 562 and the cutter roll 561 rotate, at the portion where the circumferential surface of the anvil roll 562 and the tip of the blade 561c of the cutter roll 561 come into contact, a slit (cut) corresponding to the shape of the blade 561c is formed in the base material sheet (the absorption layer 13, the sub-absorption layer 12, etc. in this embodiment) sandwiched between the two. At the same time, at the portion where the circumferential surface of the anvil roll 562 and the tip of the circumferential blade 561rc of the cutter roll 561 come into contact, the base material sheet (absorption layer 13 and sub-absorption layer 12) sandwiched between the two is cut out in a substantially elliptical shape along the shape of the circumferential blade 561rc.

[0085] Note that a part of the blade 561c of the cutter roll 561 of the second slit forming mechanism 560 is arranged at a position overlapping with the groove 552d of the anvil roll 552 of the first slit forming mechanism 550 in the CD direction (see FIG. 15B). Therefore, a part of the second slit 18b formed in the second slit forming step (S106) is formed in a portion where the first slit 18a was not formed in the first slit forming step (S105) (the portion corresponding to the groove 552d of the anvil roll 552).

[0086] After the slits 18 are formed in the absorption layer 13 (and the sub-absorption layer 12) in the first slit forming step (S105) and the second slit forming step (S106), in the thickness direction, the continuum 11a of the surface layer 11 is laminated from the skin side of the sub-absorption layer 12, and the continuum 14a of the back surface layer 14 is laminated from the non-skin side of the absorption layer 13.

[0087] Next, a cutting and sealing step is performed (S107), in which a continuous body 11a of the surface layer 11 and a continuous body 14a of the back surface layer 14, with the absorption layer 13 and the sub-absorption layer 12 sandwiched in the thickness direction, are cut into a predetermined shape and joined (sealed) using a cutting and sealing mechanism 570. In the cutting and sealing step, in a region outside the sub-absorption layer 12 (absorption layer 13), the continuous body 11a of the surface layer 11 and the continuous body 14a of the back surface layer 14 are joined using known welding means such as thermal welding or ultrasonic welding, or an adhesive such as a hot melt adhesive. That is, the surface layer 11 and the back surface layer 14 are sealed and joined in a region outside the portion surrounded by the broken line representing the sub-absorption layer 12 in the planar pad 1 shown in FIG. 1. Then, the belt-shaped continuous bodies 11a and 14a extending in the MD direction are cut along the outer edge (outline) of the pad 1 to cut out individual pads 1.

[0088] Next, a seaming step is performed (S108), in which each pad 1 is bent along the front-rear direction (MD direction) at the central portion in the width direction (CD direction) using a seaming mechanism 580. As shown in FIG. 3B, the seaming mechanism 580 bends the pad 1 into a triangular shape that bulges toward the skin side along the fold line F along the front-rear direction (MD direction).

[0089] Next, a finger insertion sheet attaching step is performed (S109), in which a finger insertion sheet 15 is attached to the non-skin side of the back surface layer 14 using a finger insertion sheet attaching mechanism 590. As shown in FIG. 3B, the finger insertion sheet attaching mechanism 590 attaches the finger insertion sheet 15 to the non-skin side of the back surface layer 14 of the pad 1 bent into a triangular shape.

[0090] Next, a loosening process is performed (S110) to loosen the pad 1 (absorbent article) using the loosening mechanism 595. FIG. 16 is a diagram for explaining the configuration and operation of the loosening mechanism 595. The loosening mechanism 595 includes a plurality of rollers 595a to 595e and two belts 595B1 and 595B2 that convey the pad 1 in the MD direction while sandwiching it vertically. In FIG. 16, five rollers, namely the first roller 595a, the second roller 595b, the third roller 595c, the fourth roller 595d, and the fifth roller 595e, are provided from the upstream side to the downstream side in the MD direction. And the belts 595B1 and 595B2 are wound around each roller. While passing the pad 1 in the conveying direction among these rollers 595a to 595e, by curving it to one side and the other side in the thickness direction along the circumferential surface of the roller, the distribution and entanglement bias of the pulp fibers constituting the absorbent layer 13 are loosened and made uniform. Note that the number and configuration of the rollers provided in the loosening mechanism 595 are not limited to those shown in FIG. 15 and can be appropriately changed according to the product specifications of the pad 1, the configuration of the manufacturing apparatus 500, and the like.

[0091] In the loosening mechanism 595, two rollers arranged adjacent to each other in the MD direction are arranged at positions shifted in the vertical direction. More specifically, as shown in FIG. 16, among the positions where the circumferential surface of the first roller 595a contacts the pad 1, the most one-side position in the vertical direction (the position of point P on the lower side of the first roller 595a in FIG. 16) is the most other-side position in the vertical direction among the positions where the circumferential surface of the second roller 595b contacts the pad 1 (the position of point Q on the upper side of the second roller 595b in FIG. 16), and each roller is arranged so as to be located on one side (lower side) in the vertical direction.

[0092] With such a configuration, the pad 1 conveyed in the MD direction is curved on one side and the other side in the thickness direction by being wound around the circumferential surface of each roller in the process of passing through each roller. For example, in FIG. 16, when the pad 1 is wound around the circumferential surface of the first roller 595a, it is greatly curved so as to be convex on the lower side (one side in the thickness direction), and when the pad 1 is wound around the circumferential surface of the second roller 595b, it is greatly curved so as to be convex on the upper side (the other side in the thickness direction). As a result, the absorption layer 13 and the sub-absorption layer 12 are easily deformed flexibly, and the fit when the pad 1 is mounted can be improved. Further, since the bias of the pulp fibers is corrected, the liquid absorption property and the liquid diffusibility are improved, and since the absorption layer 13 and the like are curved in the thickness direction, the slit 18 provided in the absorption layer 13 is easily opened.

[0093] Note that the loosening mechanism 595 may be modified as follows. FIG. 17 is a diagram for explaining a modified example of the loosening mechanism 595. In the loosening mechanism 595 shown in FIG. 17, the interval in the vertical direction between the rollers 595a to 595e adjacent in the MD direction is narrower than in the case of FIG. 16, and the pad 1 is conveyed so as to be sandwiched between adjacent rollers. In FIG. 17, the pad 1 is curved on one side and the other side in the thickness direction by being sandwiched between the lower circumferential surface of the first roller 595a and the upper circumferential surface of the second roller 595b. And by satisfying the positional relationship of the above-described points P and Q, the pad 1 can be loosened efficiently.

[0094] After the loosening process is performed, the pad 1 is individually packaged on the downstream side in the MD direction and shipped as an interlabial pad package packed one by one or in plural, and distributed in the market.

[0095] <Regarding the pulp constituting the absorbent core 132> As described above, the absorbent core 132 of the pad 1 is formed of ground pulp obtained by defibrating a pulp sheet PS1 containing hardwood pulp in the defibrating step (S201). That is, the shape and size of the pulp fibers constituting the absorbent core 132 are greatly affected by the degree of defibrillation of the pulp sheet PS1 in the defibrating step. In this embodiment, by performing defibrillation using the garnet cylinder 521m shown in FIG. 10, an absorbent core 132 (pulp fibers) having good hydrolysis and shape stability can be manufactured.

[0096] The absorbent core 132 of this embodiment is formed such that its length in the front-rear direction is 50 to 120 mm and its average basis weight is 50 to 120 gsm. Thereby, when the pad 1 is worn, it can be firmly fitted to the vaginal opening of the wearer, and good touch and liquid absorbency can be realized. And the absorbent core 132 of this embodiment contains a plurality of types of ground pulp (pulp fibers) having different lengths and shapes.

[0097] Conventionally, the ground pulp (pulp fibers) forming the absorbent core can be classified into three types of forms produced in the process of defibrillation. That is, a fiber mass in which relatively long pulp fibers are aggregated in a ball shape (hereinafter, also referred to as "NOTS (nuts)"), fibers that are short enough not to entangle with other fibers (hereinafter, also referred to as "FINE (fine)"), and fibers that are longer than FINE and shorter than NOTS (hereinafter, also referred to as "ACCEPT (accepts)"), these three types of fibers.

[0098] In the absorbent core, if the content of NOTS (knots) among such three types of fibers is high, there is a risk that the touch feeling during wearing deteriorates, or that it becomes difficult to dissolve in water when discarded in a toilet or the like after use. Also, if the content of FINE (fine) is high, the entanglement between the fibers becomes weak, and it becomes difficult for the absorbent core to stably maintain its shape, or there is a risk that the fibers come apart during use and the water retention property deteriorates. Therefore, in order to improve the shape stability, water retention property, and hydrolysis property of the absorbent core, it is preferable to increase the content of ACCEPT (accepts) in the fibers constituting the absorbent core as much as possible.

[0099] However, in the absorbent core provided in conventional absorbent articles, the content of NOTS (knots) and FINE (fine) becomes high during the process of defibrating the pulp sheet, and it has been difficult to achieve both good hydrolysis property and shape stability.

[0100] On the other hand, in the absorbent core 132 manufactured using the manufacturing apparatus 500 of the present embodiment, the contents of NOTS (knots) and FINE (fine) can be made lower than in the past. FIG. 18 is a diagram showing data comparing the content ratios of NOTS (knots), FINE (fine), and ACCEPT (accepts) between the absorbent core 132 formed by the manufacturing apparatus 500 of the present embodiment and the absorbent core formed by a conventional manufacturing method. FIG. 19 is a diagram for explaining a method of obtaining the content ratios of NOTS (knots), FINE (fine), and ACCEPT (accepts) contained in the absorbent core (pulverized pulp).

[0101] The content ratios of NOTS, FINE, and ACCEPT contained in the ground pulp are determined by conducting an evaluation test of the ground pulp in accordance with the "Sieving Test Method for Chemical Products" specified in JIS K 0069-1992. The evaluation test in this embodiment is conducted using a grinding evaluation tester 300 (for example, manufactured by Nisshin Kikai Co., Ltd.: Pulp Grinding Evaluation Tester) as shown in FIG. 19. The grinding evaluation tester 300 includes a first sieve 311 to a fifth sieve 315 and a vibration device 320. The first sieve 311 to the fifth sieve 315 are sieves each provided with a wire mesh (for example, a metal sieve mesh specified in JIS Z 8801) having different mesh numbers (meshes) at intervals of 25.4 mm. In the grinding evaluation tester 300, various meshes of 42 meshes as the first sieve, 4.7 meshes as the second sieve, 7.5 meshes as the third sieve, 14 meshes as the fourth sieve, and 60 meshes as the fifth sieve are arranged in order from the upper side in the vertical direction. The vibration device 320 is a device that applies vibration to the sieves 311 to 315.

[0102] The evaluation test of the ground pulp was conducted on the absorbent core 132 manufactured by the manufacturing apparatus 500 of this embodiment and the absorbent cores 1 to 3 manufactured by a conventional manufacturing method as comparative examples. Comparative examples 1 to 3 were those in which the defibration of the pulp was performed using a conventional Sommill as the defibrator. Comparative example 1 was defibrated with a grinding amount (kg / hm) similar to that of this embodiment. Also, comparative example 2 was defibrated with twice the grinding amount of comparative example 1, and comparative example 3 was defibrated with three times the grinding amount of comparative example 1.

[0103] When conducting the evaluation test of the ground pulp, first, after setting the vibration device 320 (strength and weakness setting dial: 70, time setting: 5 minutes, vibration: continuous), the ground pulp to be evaluated is loosened and put into the second sieve 312. The ground pulp to be evaluated is about 5 mg, and its accurate weight is measured in advance. Next, the first sieve 311 is placed on and fixed with a clamp unit, and the vibration device 320 is operated. Then, after operating for 5 minutes, the clamp unit is loosened and the first sieve 311 is removed.

[0104] At this time, the ground pulp remaining on the second screen 312 to the fourth screen 314 is defined as NOTS (nuts). That is, the weight of the fibers that do not pass through a 14-mesh or larger screen is measured as NOTS (nuts). Also, the ground pulp that did not remain on any of the screens 312 to 315 is defined as FINE (fine). That is, the weight of the fibers that passed through a 60-mesh screen is measured as FINE (fine). Further, the other ground pulp is defined as ACCEPT (accepts). That is, the fibers that passed through the second screen 312 to the fourth screen 314 and did not pass through the fifth screen 315 are defined as ACCEPT (accepts). This test is repeated a plurality of times (for example, two or more times), and the average weight is calculated for each of NOTS (nuts), FINE (fine), and FINE (fine). Then, the content ratio of each fiber is obtained from the ratio of the weight to the total weight (5 mg) of the ground pulp to be evaluated.

[0105] As a result of such a ground pulp evaluation test, in Comparative Examples 1 to 3, all contained 14% or more of NOTS (nuts). And as the defibering amount per unit time increased, the content of NOTS (nuts) increased. Also, in Comparative Examples 1 to 3, 11% to 12% of FINE (fine) was contained (see FIG. 18). In contrast, it became clear that the ground pulp constituting the absorbent core 132 of the present embodiment does not contain NOTS (nuts). Also, the FINE (fine) was 19% and the ACCEPT (accepts) was 81% (see FIG. 18).

[0106] Since the absorbent core 132 of the present embodiment has a low content ratio of NOTS (knots), it is possible to suppress large fiber lumps from remaining without being dissolved in water, and when discarded in a toilet or the like, the fibers constituting the absorbent core 132 are likely to break into fine pieces. At least, the weight ratio of NOTS (knots) to the total weight is 10% or less, and the hydrolyzability is higher compared to the case where the weight ratio of NOTS (knots) is greater than 10%. Further, in the absorbent core 132 of the present embodiment, the content ratio of FINE is 20% or less of the whole, and 80% or more of the pulp fibers (pulverized pulp) constituting the absorbent core 132 are likely to be entangled with each other. That is, the weight ratio of FINE to the total weight is 20% or less, and compared with the case where the weight ratio is greater than 20%, the pulp fibers are likely to be intertwined with each other, and the shape of the absorbent core 132 is likely to be stably maintained. Therefore, it is possible to manufacture an absorbent core 132 that has a stable shape during wearing (use) and is highly hydrolyzable and easily dissolved when discarded in a toilet or the like after use.

[0107] Further, in the fibrillation step (S201) of the present embodiment, the pulp sheet P1 is fibrillated so that the fibrillation amount per unit width is 7.5 to 60 kg / mh. When using hardwood pulp with a short fiber length, when the pulverized pulp is deposited (accumulated) in the recess 523r of the rotary drum 523, the absorbent core may be tightened and it may be difficult to transfer to the base material sheet. However, under the above conditions, it is easy to transfer to the base material sheet (the continuum 133a of the non-skin side sheet) while maintaining the shape of the absorbent core 132. In addition, if the fibrillation amount per unit time is increased (the rotation speed of the garnet cylinder 521m is increased) in the fibrillation step, the ratio of NOTS (knots) increases, and conversely, if the fibrillation amount per unit time is decreased (the rotation speed of the garnet cylinder 521m is decreased), the ratio of FINE may increase. Therefore, it is preferable to manufacture the absorbent core 132 within the above range of the fibrillation amount.

[0108] Also, in the fibrillation step (S201) of the present embodiment, fibrillation of the pulp sheet P1 containing hardwood pulp is performed using the garnet cylinder 521m around which the saw blade 525 is wound along the circumferential direction of the rotating roll. By pulverizing the pulp sheet P1 with the saw blade 525 having a large number of fine blades, it is easier to form finer pulverized pulp compared to the case of performing fibrillation using a conventional sommill or hammer mill. In particular, since it is possible to reduce the content ratio of NOTS (nuts) and increase the ratio of ACCEPT (accepts) having an appropriate size, it is suitable for manufacturing the highly hydrolyzable absorbent core 132.

[0109] Further, the absorbent core 132 of the present embodiment does not contain NOTS (nuts). As described above, if NOTS (nuts) are contained, the hydrolyzability is likely to deteriorate, and there is a risk that the absorbent core 132 is difficult to decompose when flushed into the toilet. Also, if NOTS (nuts) are contained, there will be a portion where the fiber density becomes locally high, making it difficult to achieve uniform water absorption and water retention, which may cause leakage and the like. In contrast, since the absorbent core 132 of the present embodiment does not contain NOTS (nuts), an absorbent core 132 having good water absorption / water retention and hydrolyzability can be realized.

[0110] Also, from the viewpoint of the hydrolyzability of the absorbent core 132, when the pad 1 is flushed into the toilet or the like after use, it is desirable that a large number of pulp fibers (pulverized pulp) constituting the absorbent core 132 are each easily contacted with water and are easily separated from the entangled state of the fibers. In the manufacturing method of the present embodiment, a plurality of slits 18 are formed in the absorbent core 132 (absorbent layer 13) by the slit forming steps (S105, S106). Thereby, when the pad 1 is flushed into the toilet, water is easily drawn into the absorbent core 132 through the slit 18, and the pulp fibers are easily contacted with water. Also, since the pulp fibers are loosened by the loosening step (S110), water is easily uniformly soaked throughout the absorbent core 132. Therefore, an absorbent core 132 having good hydrolyzability can be manufactured.

[0111] Further, the loosening step (S110) is performed after the slit forming steps (S105, S106). By performing in this order, each of the plurality of slits 18, 18... formed in the absorbent core 132 in the slit forming step becomes easy to spread (the cut becomes easy to open) in the loosening step. Thereby, when the pad 1 is flushed into the toilet, water becomes more likely to penetrate from the slit 18 (the cut), and water becomes more likely to reach the inside of the absorbent core 132. Therefore, the pulp fibers constituting the absorbent core 132 are more likely to come into contact with water, and the hydrolysis property can be further enhanced.

[0112] Also, in the loosening step, the pad 1 is conveyed while being curved so as to be wound around the circumferential surfaces of a plurality of rollers provided in the loosening mechanism 595. For example, in FIG. 16, the pad 1 is supported between the belts 595B1 and 595B2, and first, it is wound around the lower circumferential surface of the first roller 595a that rotates around the rotation axis along the CD direction, and is greatly curved so as to be convex downward. Then, it is conveyed to the second roller 595b, and is wound around the upper circumferential surface of 595b, thereby being greatly curved so as to be convex upward. That is, in the vertical direction, the lowest position (point P in FIG. 16) of the portion where the circumferential surface of the first roller 595a abuts on the pad 1 is lower than the highest position (point Q in FIG. 16) of the portion where the circumferential surface of the second roller 595b abuts on the pad 1, whereby the pad 1 is greatly curved up and down (in the thickness direction) along the circumferential surfaces of these rollers.

[0113] As described with reference to FIG. 5, the absorbent core 132 is provided with a plurality of first slits 18a along the width direction (CD direction) and a plurality of second slits 18b along the longitudinal direction (MD direction). Then, in the loosening process, as the pad 1 (absorbent core 132) is conveyed in the MD direction while curving in the thickness direction, the first slits 18a along the CD direction (width direction) are expanded or contracted along the circumferential surface of the roller (corresponding to the MD direction). Further, the second slits 18b along the MD direction (longitudinal direction) are expanded or contracted based on the difference in the inner and outer circumferential speeds when passing through the thickness of the absorbent core 132 and the circumferential surface of the roller. As a result, each of the plurality of slits 18, 18... is more likely to open, and when the used pad 1 is discarded in a toilet or the like, water is drawn in from the opened slits 18, thereby further enhancing the hydrolyzability of the absorbent core 132.

[0114] Also, in the loosening process, the pad 1 is conveyed with the longitudinal direction along the MD direction. As shown in FIGS. 1 and 5, the pad 1 is formed in a substantially elliptical shape that is longer in the longitudinal direction than in the width direction so as to fit the crotch of the wearer. That is, the pad 1 is conveyed in a state where the length in the MD direction is longer. As a result, in the plurality of rollers 595a to 595e provided in the loosening mechanism 595, the pad 1 is more likely to bend significantly. For example, in FIG. 16, the pad 1 is wound along the circumferential surface in a wide upper half range in the circumferential direction of the second roller 595b, resulting in a state of bending nearly 180 degrees. On the other hand, if the length of the pad 1 in the MD direction is short, the range in which the pad 1 is wound in the circumferential direction of the second roller 595b becomes narrow, so the degree of bending is smaller than in the above case. Thus, in the present embodiment, by conveying the pad 1 in a state where the longitudinal direction is along the MD direction so that the length in the MD direction is longer, the pad 1 (absorbent core 132) can be efficiently bent in the loosening process.

[0115] At this time, the length L13 of the absorbent core 132 in the machine direction (MD direction) is preferably longer than twice the diameter of each roller (for example, the diameter d595a of the first roller 595a, etc.). As described above, in order to efficiently bend the absorbent core 132 (pad 1) in the relaxation process, it is desirable that the absorbent core 132 be wound around the circumferential direction of the roller in as wide a range as possible. Here, since the length in the circumferential direction of the roller is approximately 3.14 times the diameter of the roller, if the length L13 of the absorbent core 132 in the machine direction (MD direction) is 1.57 times the diameter of the roller, the absorbent core 132 will theoretically be wound around in a range of 1 / 2 in the circumferential direction of the roller. Therefore, by making the length L13 of the absorbent core 132 in the machine direction (MD direction) longer than twice the diameter of the roller, even considering errors during conveyance by the belts 595B1 and 595B2, as shown in FIG. 16, the pad 1 can be easily and firmly wound around the circumferential surface of the roller. As a result, it becomes easier to greatly bend the pad 1, and the slit 18 becomes more likely to open. Therefore, the hydrolysis resistance can be further improved.

[0116] Further, the loosening step (S110) is performed after the sealer step (S108). In the sealer step, the absorbent core 132 (pad 1) is folded in half along a folding line extending in the longitudinal direction (MD direction) at the center in the width direction (CD direction). That is, the regions on one side and the other side of the absorbent core 132 from the center in the width direction (CD direction) are folded one on top of the other in the thickness direction and conveyed in the MD direction in a state where the thickness is increased. Then, on the downstream side in the MD direction, when the absorbent core 132 curves along the peripheral surfaces of the rollers 595a to 595d of the loosening mechanism 595, the thicker it is, the longer the distance in the radial direction from the rotation center of the roller becomes, and it becomes easier to be pulled in the circumferential direction (MD direction) of the roller. For example, in FIG. 16, the pad 1 along the peripheral surface of the second roller 595b is more likely to be strongly pulled in the circumferential direction at a point R away from the peripheral surface than at a point Q in contact with the peripheral surface. In this case, the slit 18 provided closer to the point R is more likely to open than the slit 18 provided closer to the point Q in the thickness direction. Therefore, by loosening the absorbent core 132 that has been folded in half and thickened in the sealer step in the loosening step, the slit 18 becomes more likely to open, and the hydrolysis property can be further improved.

[0117] Also, it is preferable that the total length of the plurality of first slits 18a, 18a... provided in the absorbent core 132 is longer than the total length of the plurality of second slits 18b, 18b.... Although it has been described that the slit 18 is made easier to open by curving the absorbent core 132 conveyed along the MD direction in the thickness direction in the loosening step, at this time, the first slit 18a along the CD direction is more likely to open larger than the second slit 18b along the MD direction. Therefore, if the total length of the first slits 18a is longer than the total length of the second slits 18b, the length at which the slit 18 is likely to open as a whole becomes longer. That is, more slits 18 can be efficiently opened. Thereby, the hydrolysis property of the absorbent core 132 can be improved.

[0118] ===Other Embodiments=== The embodiments of the present invention have been described above. However, the above embodiments are for facilitating the understanding of the present invention and are not for limiting the interpretation of the present invention. Further, the present invention can be modified and improved without departing from its gist, and it goes without saying that equivalents thereof are included in the present invention.

[0119] In the above embodiment, it has been described that the absorbent core 132 of the absorption layer 13 is composed of short fibers having an average fiber length of about 0.8 mm. Conventionally, when it is desired to finely pulverize pulp to shorten the fiber length, it is generally performed to add a softening agent (debonder) such as a quaternary ammonium surfactant to the pulp sheet before pulverization to make the pulp easier to pulverize (so-called treated pulp). However, when using a softening agent (debonder), there is a risk that water absorption may be easily inhibited.

[0120] Therefore, it is preferable that the water-absorbent fibers constituting the absorbent core 132 of the pad 1 are configured without containing a softening agent (debonder). Thereby, it is suppressed that the water retention performance of the absorbent core 132 is deteriorated. In the above embodiment, since the absorbent core 132 is formed using hardwood pulp, it is possible to make the average fiber length about 0.8 mm without using a softening agent (debonder), and an absorbent core 132 excellent in water absorption and flexibility can be realized.

[0121] In the above embodiment, the pad 1 having a configuration in which the absorption layer 13 is disposed on the non-skin side rather than the sub-absorption layer 12 has been described (see FIG. 2 etc.). However, these arrangements may be reversed in the thickness direction. For example, a configuration in which the sub-absorption layer 12 is disposed on the non-skin side in the thickness direction of the absorption layer 13 may be adopted. Further, the pad 1 may be configured to include only the absorption layer 13 without providing the sub-absorption layer 12.

Explanation of reference numerals

[0122] 1 Interlabial pad (pad, absorbent article), 11 Surface layer, 11a Continuum, 12 Sub-absorption layer, 13 Absorbing layer, 131 Skin-side sheet, 131a Continuum, 132 Absorbent core, 133 Non-skin-side sheet, 133a Continuum, 14 Back surface layer, 14a Continuum, 15 Finger insertion sheet, 15de Non-joint portion of finger insertion sheet, 16 Finger insertion sheet joint, 17 Back surface layer joint, 18 Slit, 18a First slit, 18b Second slit, 19 Squeezing portion, 20 Finger insertion portion, 300 Crushing evaluation tester, 311 First sieve, 312 Second sieve, 313 Third sieve, 314 Fourth sieve, 315 Fifth sieve, 320 Vibration device, 500 Manufacturing device, 510 Conveying mechanism, 520 Absorbent core laminating mechanism, 521 Defibering device, 521m Garnet cylinder, 521mf Peripheral surface, 521Ar Rotation shaft, 522 Material supply section, 523 Rotating drum, 523r Recess, 525 Saw blade, 526 Feed roll, 530 Sub-absorbing layer laminating mechanism, 531 Defibering device, 531m Garnet cylinder, 540 Reversing mechanism, 550 First slit forming mechanism, 551 Cutter roll, 551f Peripheral surface, 551c Blade, 552 Anvil roll, 552f Peripheral surface, 552d Groove, 560 Second slit forming mechanism, 561 Cutter roll, 561f Peripheral surface, 561c Blade, 561rc Circumferential blade, 562 Anvil roll, 570 Cutting and sealing mechanism, 580 Sealer mechanism, 590 Finger Insertion Sheet Attachment Mechanism, 595 Release Mechanism, 595a First Roller, 595b Second Roller, 595c Third Roller, 595d Fourth Roller, F Fold Line (Bending Line), PS1 Pulp Sheet, PS2 Pulp Sheet, CR Central Region, SR End Region

Claims

1. A method for manufacturing an interlabial pad having an absorbent core, comprising: a defibrillation step of defibrillating a pulp sheet containing hardwood pulp into pulverized pulp; an absorbent core forming step of accumulating the pulverized pulp to form the absorbent core; and when a pulp pulverization state evaluation test is performed on the pulverized pulp by passing it through a plurality of types of sieves having different mesh numbers at 25.4 mm intervals, the proportion of the weight of fibers that do not pass through a sieve of 14 mesh or more is 10% or less with respect to the total weight of the pulverized pulp to be evaluated, and the proportion of the weight of fibers that pass through a 60-mesh sieve is 20% or less with respect to the total weight of the pulverized pulp to be evaluated. The method for manufacturing an interlabial pad is characterized in that the pulp sheet is defibrillated in the defibrillation step as described above.

2. The method for manufacturing an interlabial pad according to Claim 1, wherein in the defibrillation step, the defibrillation amount per unit width of the pulp sheet is 7.5 to 60.0 kg / mh.

3. The method for manufacturing an interlabial pad according to Claim 1 or 2, wherein in the defibrillation step, the pulp sheet is defibrillated using a garnet cylinder around which a saw blade is wound along the circumferential direction of a rotating roll.

4. The method for manufacturing an interlabial pad according to Claim 1 or 2, wherein the pulverized pulp does not contain fibers that do not pass through the sieve of 14 mesh or more when the pulp pulverization state evaluation test is performed.

5. The method for manufacturing an interlabial pad according to Claim 1 or 2, comprising: a conveying step of conveying the absorbent core in a conveying direction; a slit forming step of forming a slit in the conveyed absorbent core; and a loosening step of loosening the pulverized pulp constituting the absorbent core. The method for manufacturing an interlabial pad is characterized by having the above steps.

6. The method for manufacturing an interlabial pad according to Claim 5, wherein the loosening step is performed after the slit forming step.

7. The method for manufacturing an interlabial pad according to Claim 6, The loosening step is performed by conveying the pad between the labia along the conveying direction while sandwiching the pad between the labia between a first roller that rotates around a rotation axis along a direction perpendicular to the conveying direction and a second roller that is provided adjacent to the downstream side of the first roller in the conveying direction and that rotates around a rotation axis along a direction perpendicular to the conveying direction. A method for manufacturing a pad between labia, characterized in that, in the vertical direction, the position on one side that is the most among the portions where the circumferential surface of the first roller contacts the pad between the labia is located on one side with respect to the position on the other side that is the most among the portions where the circumferential surface of the second roller contacts the pad between the labia. **Claim 8** A method for manufacturing a pad between labia according to claim 7, wherein the absorbent core has a front-back direction and a width direction, the length of the absorbent core in the front-back direction is longer than the length in the width direction, and in the loosening step, the absorbent core is conveyed in a state where the front-back direction is along the conveying direction. A method for manufacturing a pad between labia, characterized by this. **Claim 9** A method for manufacturing a pad between labia according to claim 8, wherein the length of the absorbent core in the front-back direction is longer than twice the diameter of the first roller. A method for manufacturing a pad between labia, characterized by this. **Claim 10** A method for manufacturing a pad between labia according to claim 8, further comprising a seaming step of folding the absorbent core in half along a fold line along the front-back direction, and the loosening step is performed after the seaming step. A method for manufacturing a pad between labia, characterized by this. **Claim 11** A method for manufacturing a pad between labia according to claim 8, wherein in the slit forming step, a plurality of first slits along the width direction and a plurality of second slits along the front-back direction are formed, and the total length of the plurality of first slits is longer than the total length of the plurality of second slits. A method for manufacturing a pad between labia, characterized by this. **Claim 12** A pad between labia comprising an absorbent core having a pulverized pulp obtained by defibrating a pulp sheet containing hardwood pulp, when a pulp pulverization state evaluation test is performed on the pulverized pulp by passing it through a plurality of types of sieves having different mesh numbers at 25.4 mm intervals, the ratio of the weight of fibers that do not pass through a sieve of 14 mesh or more is 10% or less with respect to the total weight of the pulverized pulp to be evaluated, and The labial pad is characterized in that the weight ratio of the fibers passing through a 60-mesh sieve is 20% or less with respect to the total weight of the ground pulp to be evaluated.

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