Method of manufacturing interlabial pad, and interlabial pad

Abstract

The present invention includes: a fiber-breakdown step (S201) of breaking down fibers in a pulp sheet containing hardwood pulp into ground pulp; and an absorbent-core forming step (S202) of cumulating the ground pulp to form an absorbent core (132). The pulp sheet is broken down in the fiber-breakdown step so that, when a pulp ground-state evaluation test is conducted in which the ground pulp is passed through multiple types of sieves having different mesh counts in a 25.4 mm interval, the ratio of the weight of fibers not passing through sieves (312–314) of 14 mesh or greater is 10% or less, and the ratio of the weight of fibers passing through a 60-mesh sieve (315) is 20% or less, with respect to the total weight of the ground pulp to be evaluated.

Description

Method for manufacturing interlabial pad and interlabial pad

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

[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), multiple slits are provided in a highly rigid member such as an absorbent body, allowing the pad to easily deform three-dimensionally to conform to the contours of the wearer's body, thereby improving the fit when worn. For example, Patent Document 1 discloses an interlabial pad with multiple slits provided along the longitudinal and lateral directions of the product.

[0003] Japanese Patent Application Laid-Open No. 2004-97693

[0004] In recent years, attention has been focused on a technology for forming an absorbent core using pulp containing short-fiber hardwood pulp in such interlabial pads, thereby increasing the water-decomposability of the absorbent core and enabling it to dissolve in water and easily break apart when flushed down the toilet after use. However, with conventional manufacturing methods, when pulp containing hardwood pulp is defibrated, it ends up containing many large fiber clumps (knots) and excessively fine fibers (fines), making it difficult to manufacture an absorbent core that combines good water-decomposability and shape stability.

[0005] The present invention has been made in view of the above-mentioned problems, and its object is to provide an interlabial pad having an absorbent core that has good water-disintegrability and shape stability.

[0006] The main invention for achieving the above object is a method for manufacturing an interlabial pad with an absorbent core, comprising a defibrating step of defibrating a pulp sheet containing hardwood pulp to form ground pulp, and an absorbent core formation step of collecting the ground pulp to form the absorbent core, wherein the pulp sheet is defibrated in the defibrating step so that, when a pulp ...

[0007] Other features of the present invention will become apparent from the description of this specification and the accompanying drawings.

[0008] According to the present invention, an interlabial pad having an absorbent core with good water-disintegrability and shape stability can be provided.

[0009] [Correction based on Rule 91 08.01.2025] This is a plan view of the pad 1 in an unfolded state. It is a schematic cross-sectional view taken along the line A-A in FIG. 1. It is a diagram illustrating the configuration of the pad 1. It is a diagram illustrating the configuration of the pad 1. It is a plan view illustrating the configuration of the absorbent layer 13. It is a diagram illustrating the fiber length distribution of hardwood water-absorbent fibers (hardwood pulp) and softwood water-absorbent fibers (softwood pulp). It is a flow diagram illustrating the manufacturing process of the pad 1. It is a schematic diagram illustrating a manufacturing apparatus 500 for manufacturing absorbent articles such as the pad 1. It is a flow diagram illustrating the specific operations (steps) performed in the absorbent core lamination step (S102). FIGS. 10A to 10C are diagrams illustrating the configuration of the garnet cylinder 521m. They are diagrams illustrating a method for defibrating the pulp sheet PS1 using the garnet cylinder 521m. FIGS. 12A to 12C are diagrams illustrating the configuration of the cutter roll 551 used to form the first slits 18a. 13A and 13B are diagrams illustrating the configuration of the anvil roll 552 used when forming the first slit 18a.

[0043] Figures 13A and 13B are diagrams illustrating the operation of forming the first slit 18a using the cutter roll 551 and the anvil roll 552.

[0044] Figures 15A to 15C are diagrams illustrating the configuration of the cutter roll 561 used when forming the second slit 18b.

[0045] Figures 15A to 15C are diagrams illustrating the configuration and operation of the refining mechanism 595.

[0046] Figures 15A to 15C are diagrams illustrating modified examples of the refining mechanism 595.

[0047] Figures 15A and 15C present data comparing the content ratios of NOTS, FINE, and ACCEPT in an absorbent core 132 formed by the manufacturing apparatus 500 and an absorbent core formed by a conventional manufacturing method.

[0048] Figures 15A and 15C are diagrams illustrating a method for determining the content ratios of NOTS, FINE, and ACCEPT in an absorbent core (crushed pulp).

[0010] At least the following points become clear from the description in this specification and the accompanying drawings: (Aspect 1) A method for manufacturing an interlabial pad with an absorbent core, comprising: a defibrating step of defibrating a pulp sheet containing hardwood pulp to form ground pulp; and an absorbent core formation step of collecting the ground pulp to form the absorbent core, wherein the pulp sheet is defibrated in the defibrating step so that, when a pulp crushing state evaluation test is conducted in which the ground pulp is passed through several types of sieves each having a different mesh size of 25.4 mm, the proportion of the weight of fibers that do not pass through a 14 mesh or larger sieve to the total weight of the ground pulp being evaluated is 10% or less, and the proportion of the weight of fibers that pass through a 60 mesh sieve to the total weight of the ground pulp being evaluated is 20% or less.

[0011] According to the interlabial pad manufacturing method of Aspect 1, the proportion of large fiber agglomerates (NOTS) that do not pass through a 14-mesh or larger sieve is low at 10% or less, which makes it easier to prevent fiber agglomerates from remaining undisintegrated in water compared to the reverse case. Furthermore, the proportion of fine fibers (FINE) that pass through a 60-mesh sieve is low at 20% or less, which makes it easier for the fibers to intertwine with each other and more stable the shape of the absorbent core compared to the reverse case. Therefore, it is possible to manufacture an interlabial pad with an absorbent core that maintains its shape when worn and is highly water-disintegrable and easy to disintegrate when discarded in a toilet or the like after use. (Aspect 2) The interlabial pad manufacturing method according to Aspect 1, wherein the defibration amount per unit width of the pulp sheet in the defibration step is 7.5 to 60.0 kg / mh.

[0012] According to the method for manufacturing an interlabial pad of Aspect 2, there is a risk that increasing the amount of defibration per unit time in the defibrating step will increase the proportion of NOTS, and decreasing the amount of defibration per unit time will increase the proportion of FINE, but by performing defibration so that the defibration rate of the pulp fibers satisfies the condition of 7.5 to 60 kg / mh, it is possible to make it easier to transfer the absorbent core to the base sheet while maintaining its shape. (Aspect 3) The method for manufacturing an interlabial pad of any of Aspects 1 and 2, wherein in the defibrating step, the pulp sheet is defibrated using a garnet cylinder with a saw blade wound around the circumferential direction of a rotating roll.

[0013] According to the method for manufacturing an interlabial pad of Aspect 3, by pulverizing the pulp sheet with a saw blade having many fine teeth, it is easier to form finer pulp than when defibrating using a conventional saw mill or hammer mill. In particular, since it is possible to reduce the proportion of NOTS in the pulp, it is suitable for manufacturing absorbent cores that are highly water-decomposable. (Aspect 4) The method for manufacturing an interlabial pad of any of Aspects 1 to 3, wherein the pulp does not contain fibers that do not pass through a sieve of 14 mesh or larger when the pulp pulverization state evaluation test is conducted.

[0014] According to the method for manufacturing an interlabial pad of Aspect 4, because the absorbent core does not contain NOTS, areas where the fiber density is locally high are less likely to occur, and water absorption and water retention tend to be uniform. Furthermore, water disintegrability is improved, making the absorbent core more likely to disintegrate when flushed down the toilet. Therefore, it is possible to manufacture an absorbent core with good water absorption, water retention, and water disintegrability. (Aspect 5) The method for manufacturing an interlabial pad according to any of Aspects 1 to 4, comprising a conveying step of conveying the absorbent core in a conveying direction, a slit forming step of forming slits in the absorbent core being conveyed, and a loosening step of loosening the pulverized pulp that constitutes the absorbent core.

[0015] According to the method for manufacturing an interlabial pad of Aspect 5, a slit is formed in the absorbent core in the slit-forming step. As a result, when the used interlabial pad is flushed down a toilet or the like, water is more easily drawn into the absorbent core through the slit, making it easier for the pulp fibers to come into contact with water. Furthermore, the loosening step loosens the pulp fibers, making it easier for water to permeate evenly throughout the absorbent core. Therefore, an absorbent core with good water-disintegratability can be manufactured. (Aspect 6) A method for manufacturing an interlabial pad according to any of Aspects 1 to 5, in which the loosening step is performed after the slit-forming step.

[0016] According to the method for manufacturing an interlabial pad of aspect 6, each of the multiple slits formed in the absorbent core in the slit-forming step is likely to widen in the loosening step. This makes it easier for water to penetrate through the slits and reach the inside of the absorbent core when the used interlabial pad is flushed down a toilet, etc. This facilitates contact between water and the pulp fibers that make up the absorbent core, further improving water-disintegrability. (Aspect 7) The method for manufacturing an interlabial pad according to any one of Aspects 1 to 6, wherein the loosening step is carried out by transporting the interlabial pad along the transport direction while sandwiching it between a first roller that rotates about a rotation axis that aligns in a direction perpendicular to the transport direction, and a second roller that is provided adjacent to and downstream of the first roller in the transport direction and rotates about a rotation axis that aligns in a direction perpendicular to the transport direction, and wherein, in the vertical direction, the position furthest to one side of the portion where the circumferential surface of the first roller abuts against the interlabial pad is located to one side of the position furthest to the other side of the portion where the circumferential surface of the second roller abuts against the interlabial pad.

[0017] According to the method for manufacturing an interlabial pad of Aspect 7, during the loosening process, the interlabial pad is conveyed in the conveyance direction (MD direction) while wrapping around the circumferential surfaces of rollers such as the first roller and the second roller, curving to one side and the other in the thickness direction, thereby widening and narrowing the slits in the absorbent core. This makes it easier for each of the multiple slits to open, and when the used interlabial pad is discarded in a toilet or the like, water is more easily drawn in through the open slits, further improving the water-disintegratability of the absorbent core. (Aspect 8) The method for manufacturing an interlabial pad of any of Aspects 1 to 7, wherein the absorbent core has a front-to-rear direction and a width direction, the length of the absorbent core in the front-to-rear direction is longer than the length in the width direction, and during the loosening process, the absorbent core is conveyed with the front-to-rear direction aligned with the conveyance direction.

[0018] According to the method for manufacturing an interlabial pad of Aspect 8, the absorbent core is easily wrapped around a wide area in the circumferential direction of the roller by being transported in a state in which its length in the MD direction is increased. In other words, by wrapping the absorbent core around the circumferential surface of the roller as long as possible, the absorbent core is easily curved. This makes it easier to open the slit. (Aspect 9) The method for manufacturing an interlabial pad of any of Aspects 1 to 8, wherein the length of the absorbent core in the front-to-rear direction is longer than twice the diameter of the first roller.

[0019] According to the method for manufacturing an interlabial pad of Aspect 9, the absorbent core is more likely to wrap around nearly half of the rollers in the circumferential direction. Therefore, the absorbent core is more likely to curve along the circumferential surface of each roller. This makes it easier to open the slits, further improving water-disintegratability. (Aspect 10) The method for manufacturing an interlabial pad according to any of Aspects 1 to 9, further comprising a sailing step in which the absorbent core is folded in half along a fold line along the front-to-rear direction, and the unraveling step is carried out after the sailing step.

[0020] According to the method for manufacturing an interlabial pad of aspect 10, the absorbent core, which has been folded in half in the sailing process and has become thicker, is loosened in the loosening process, making it easier for the slits to open and further improving water-disintegratability.

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

[0022] According to the method for manufacturing an interlabial pad of Aspect 11, by curving the absorbent core in the thickness direction as it is transported in the MD, the first slits in the CD direction are more likely to open than the second slits in the MD. Therefore, if the total length of the first slits is longer than the total length of the second slits, the overall length over which the slits are more likely to open is longer. This improves the water-disintegrability of the absorbent core.

[0023] (Mode 12) An interlabial pad comprising an absorbent core having ground pulp formed by defibrating a pulp sheet containing hardwood pulp, wherein when a pulp ground pulp is subjected to a pulp ground state evaluation test in which the ground pulp is passed through several types of sieves each having a different mesh size of 25.4 mm, the weight of fibers that do not pass through a 14 mesh or larger sieve is 10% or less of the total weight of the ground pulp being evaluated, and the weight of fibers that pass through a 60 mesh sieve is 20% or less of the total weight of the ground pulp being evaluated.

[0024] (Aspect 12) In the interlabial pad of Aspect 12, the proportion of large fiber clumps (NOTS) that do not pass through a 14-mesh or larger sieve is low at 10% or less, which makes it easier to prevent fiber clumps from remaining undisintegrated in water compared to the reverse case. Furthermore, the proportion of fine fibers (FINE) that pass through a 60-mesh sieve is low at 20% or less, which makes it easier for the fibers to intertwine with each other and more stable the shape of the absorbent core compared to the reverse case. This makes it possible to realize an interlabial pad with an absorbent core that maintains its shape when worn and is highly water-disintegrable and easy to disintegrate when discarded in a toilet or other similar facility after use. == ...

[0025] <Basic Structure of Interlabial Pad 1> Fig. 1 is a plan view of the pad 1 in an unfolded state. Fig. 1 is a view of the pad 1 as seen from the skin-facing side. Fig. 2 is a schematic cross-sectional view taken along the line A-A in Fig. 1. Figs. 3 and 4 are diagrams illustrating the structure of the pad 1. In each diagram (Figs. 1 to 4), the center C-C indicates the center in the width direction, and the center CL indicates the center in the front-to-back direction of the absorbent layer 13 (described below) when the pad 1 is viewed in the thickness direction. Furthermore, Figs. 1 and 2 are views of a state in which a finger-insertion sheet 15 (described below) has been cut at the center C-C and the pad 1 has been placed flat on a flat surface (a "flat-laid" state).

[0026] The pad 1 has a front-to-rear direction, a width direction, and a thickness direction, which are perpendicular to each other. In the front-to-rear direction of the pad 1, the side that faces the wearer's abdomen when worn is referred to as the "front side," and the side that faces the wearer's back is referred to as the "rear side." In addition, in the thickness direction of the pad 1, the side that comes into contact with the wearer's skin is referred to as the "skin side," and the opposite side is referred to as the "non-skin side."

[0027] As shown in Figures 1 to 4, the pad 1 has a generally elliptical shape in plan view, with its front-to-back length longer than its width, is symmetrical about the widthwise center C-C, and has a narrowed portion at the front-to-back center CL, which is constricted inward in the widthwise direction. Furthermore, the pad 1 has an asymmetrical shape with respect to the front-to-back center in plan view. Specifically, the center CL (the front-to-back center of the absorbent layer 13) is located rearward of the front-to-back center of the pad 1, and the distance from the front end of the pad 1 to the front end of the absorbent layer 13 is longer than the distance from the rear end of the pad 1 to the rear end of the absorbent layer 13. In other words, the absorbent layer 13 is positioned closer to the rear in the front-to-back direction of the pad 1. As shown in Figures 2 to 4, the pad 1 includes a surface layer 11, a secondary absorbent layer 12, an absorbent layer 13, a back layer 14, and a finger-insertion sheet 15.

[0028] The pad 1 of this embodiment is stored and distributed as a product folded toward the non-skin side along the fold line F. Figures 3 and 4 are diagrams illustrating the pad 1 disassembled into its individual components. As shown in Figure 3A, the pad 1 of this embodiment is folded toward the non-skin side along the fold line F (fold line) in the widthwise center (center C-C). A finger insertion sheet 15 for forming the finger insertion section 20 is fixed to the most non-skin side using an adhesive such as a hot melt adhesive HMA. The fold line F is a folding portion provided in the widthwise center along the front-to-rear direction. The fold line F has a predetermined width, and the apex of the fold line F on the skin side (the portion that protrudes most toward the skin) is approximately at the same position as the center C-C in the widthwise direction. Figure 3B shows the finger insertion sheet 15 separated from the back layer 14, and Figure 3C shows the pad 1 from which the finger insertion sheet 15 has been removed, horizontally positioned from the folded state along the fold line F. Then, from the state shown in Figure 3C, as shown in Figure 4, the surface layer 11, auxiliary absorbent layer 12, absorbent layer 13, and back layer 14 are stacked in order from the skin side in the thickness direction, and at least some of these components are bonded together with an adhesive or the like (see Figure 2).

[0029] The surface layer 11 is located closest to the skin and is the component that contacts the wearer's skin (between the labia) when worn, so it is preferable to use a soft sheet that is less irritating to the skin. The surface layer 11 forms the outer shape of the pad 1 and is a liquid-permeable sheet component. Examples of the surface layer 11 include nonwoven fabrics obtained by manufacturing methods such as meltblown, spunbond, pointbond, through-air, needle-punched, dry / wet spunlace, and foam film, either alone or in combination. Fiber sheet components containing rayon, acetate, cotton, pulp, or synthetic resins (e.g., polyethylene terephthalate (PET), polypropylene (PP), polyethylene PE, etc.), either alone or in combination to form a core-sheath structure, can also be used. The pad 1 of this embodiment uses a sheet component made of rayon and polyethylene terephthalate.

[0030] The auxiliary absorbent layer 12 is positioned closer to the skin than the surface layer 11 and closer to the skin than the absorbent layer 13. The auxiliary absorbent layer 12 acts as a cushioning layer between the surface layer 11 and the absorbent layer 13, flexibly adapting to changes in the wearer's movements, labia behavior, and pressure from clothing, thereby changing shape and reducing discomfort to the wearer. The auxiliary absorbent layer 12 is generally elliptical, smaller than the surface layer 11, and located approximately in the center of the pad 1 (more precisely, toward the rear). The auxiliary absorbent layer 12 is narrowed inward in the width direction at a center CL in the front-to-back direction. The auxiliary absorbent layer 12 can be made of, for example, pulp, chemical pulp, rayon, acetate, natural cotton, or synthetic fibers, either alone or in combination. In this embodiment, a mixture of pulp fiber, rayon fiber, and polyethylene terephthalate (PET) is primarily used.

[0031] The absorbent layer 13 is an absorbent body that is located closer to the skin than the auxiliary absorbent layer 12 and closer to the skin than the back surface layer 14, and absorbs bodily fluids such as excrement. The absorbent layer 13 has a generally elliptical shape and is located in the approximate center (more precisely, toward the rear side) of the pad 1. Details of the absorbent layer 13 will be described later.

[0032] The back surface layer 14 is a sheet member located closer to the skin than the absorbent 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 a plan view. The back surface layer 14 can be a sheet member such as a liquid-permeable sheet or a liquid-impermeable sheet, and can be, for example, a synthetic resin sheet film, a breathable film, pulp, paper, a nonwoven fabric, a breathable liquid-blocking sheet, or a sheet member made from a combination of these. In this embodiment, a sheet member made from a mixture of rayon, polyethylene terephthalate (PET), and pulp is used.

[0033] The finger insertion sheet 15 is a sheet member for forming the finger insertion section 20. The finger insertion section 20 is a space between the finger insertion sheet 15 and the back layer 14, and is a space into which the wearer inserts their finger when wearing the pad 1. The finger insertion sheet 15 is shorter in the front-to-back direction than the back layer 14 and shorter in the width direction than the back layer 14. The finger insertion sheet 15 is located on the non-skin side of the back layer 14, on the rear side in the front-to-back direction. Both widthwise ends of the finger insertion sheet 15 are joined and fixed to the non-skin side of the back layer 14 by finger insertion sheet joints 16 formed with an adhesive such as a hot melt adhesive (see FIG. 2). The front end and the rear end of the finger insertion sheet 15 each have an opening where the finger insertion sheet 15 and the back layer 14 are not fixed with an adhesive. The front opening is larger than the rear opening. The wearer can insert a finger (for example, a middle finger) through the opening on the front side of the finger insertion section 20, support the pad 1, and place the pad 1 against the labia to wear it.

[0034] The finger insertion sheet 15 can be made of the same material as the front layer 11 and the back layer 14. Examples of suitable materials include spunlace nonwoven fabrics, shrink-type nonwoven fabrics, and extensible spunbond nonwoven fabrics made from composite synthetic fibers such as PE / PP, PE / PET, and PP / PP; sheet materials made from fibers of rayon, acetate, cotton, pulp, or synthetic resin (e.g., polyethylene terephthalate (PET)); and sheet materials such as breathable films, paper, and breathable liquid-blocking sheets. Other suitable materials include films made from synthetic rubber or amorphous olefin resin; perforated foam films, nets, woven fabrics, or fabrics made from woven fabrics woven with spun filaments made from synthetic rubber; spunbond nonwoven fabrics or meltblown nonwoven fabrics primarily made from synthetic rubber; and expanded foam sheets. In this embodiment, sheet materials primarily made from pulp and rayon are used.

[0035] In the present embodiment, the pad 1 is folded away from the skin at the fold line F when unused, but this is not limited to this. For example, the pad may be unfolded and have no fold line F when unused, and the wearer may fold the pad away from the skin when wearing it. The pad may also have multiple fold lines F. The fold line F may have a so-called crease, or may not have a crease.

[0036] <About Wearing Pad 1> Pad 1 is worn by folding the widthwise center portion toward the non-skin side along the front-to-rear direction and bringing it into contact with the wearer's skin (excretory opening). Pad 1 of this embodiment is a sanitary product, and can be worn by folding it toward the non-skin side along fold line F so that it is convex toward the skin, and then sandwiching the widthwise center portion of pad 1 between the woman's labia. Pad 1 adheres more closely to the body (excretory opening) than a sanitary napkin, making it less likely for excreta (menstrual blood) to leak and less likely to cause discomfort during excretion.

[0037] To wear the pad 1, the wearer inserts a finger (index finger or middle finger) into the finger insertion section 20 from the front side of the pad 1 folded at the fold F, and then places the pad 1 between the labia from the ventral side, sandwiching it between the labia. After use, the worn pad 1 can be dropped into the toilet bowl (toilet) or can be grasped with the hand and placed in the toilet bowl, and then flushed down the toilet. To facilitate flushing, the components and adhesives constituting the pad 1 are preferably made of biodegradable, water-dispersible, or water-soluble materials. Flushing the pad 1 down the toilet reduces the effort required to dispose of the pad 1 as waste and reduces the amount of waste.

[0038] "Biodegradable" refers to a material's ability to break down into gases such as carbon dioxide or methane, water, and biomass under anaerobic or aerobic conditions in the presence of bacteria such as actinomycetes or other microorganisms, following natural processes. The biodegradability (biodegradation rate, biodegradability, etc.) of the material is comparable to that of naturally occurring materials such as fallen leaves, or synthetic polymers generally recognized as biodegradable under the same conditions. "Water-dispersible" refers to the property of fibers that are easily dispersed into small fragments in large amounts of water or flowing water, at least small enough not to clog ordinary toilet plumbing, while not affected by the limited amount of water (menstrual blood) present when worn. "Water-soluble" refers to the property of fibers that are easily dispersed in large amounts of water or flowing water, at least small enough not to clog ordinary toilet plumbing, while not affected by the limited amount of water (menstrual blood) present when worn.

[0039] <Absorbent Layer 13> Fig. 5 is a plan view illustrating the configuration of the absorbent layer 13. The absorbent layer 13 of this embodiment includes, in order from the skin side in the thickness direction, a skin-side sheet 131, an absorbent core 132, and a non-skin-side sheet 133. As shown in Fig. 5, when the pad 1 is divided into three equal parts in the width direction, the central region is referred to as a central region CR, and the regions on both sides are referred to as edge regions SR.

[0040] The absorbent core 132 is a portion with water-absorbing and water-retentive properties that absorb and retain liquids (body fluids) such as menstrual blood, and can be made of, for example, pulp, chemical pulp, rayon, acetate, natural cotton, synthetic fibers, cellulose foam, open-cell foam of synthetic resin, etc., either alone or in combination. Also, a particulate absorbent polymer and a fibrous absorbent polymer may be mixed, or a sheet-like absorbent polymer may be used. Furthermore, in order to maintain the bulk of the absorbent core and increase water-retentive properties, a mixture of chemical pulp, acetate, and synthetic fibers that have been cross-linked and crimped with a cross-linking agent may be used. The pad 1 uses pulp fibers (absorbent fibers) molded into a predetermined shape.

[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 materials that can be used for the skin-side sheet 131 and the non-skin-side sheet 133 include pulverized pulp, cellulose such as cotton, regenerated cellulose such as rayon and fibril rayon, semi-synthetic cellulose such as acetate and triacetate, and thermoplastic hydrophobic chemical fibers that have been hydrophilized. In this embodiment, the skin-side sheet 131 of the pad 1 is a sheet made of spunlace pulp and rayon, and the non-skin-side sheet 133 is a sheet made of pulp such as 100% pulp wetlaid tissue.

[0042] Furthermore, the provision of the skin-side sheet 131 makes it easier to spread the excrement that reaches the absorbent layer 13 in the horizontal direction, and the horizontally spread excrement can be absorbed by the absorbent core 132. This makes it easier for the absorbent core 132 to quickly absorb the excrement, which helps to reduce discomfort felt by the wearer's skin.

[0043] The absorbent layer 13 also has multiple slits 18 and multiple compressed portions 19 (not shown in FIG. 5 ). The slits 18 are cuts that penetrate at least the absorbent layer 13 (skin-side sheet 131, absorbent core 132, and non-skin-side sheet 133) in the thickness direction. However, the slits 18 may also penetrate the absorbent layer 13 and auxiliary absorbent layer 12 in the thickness direction. The slits 18 allow the absorbent layer 13 and auxiliary absorbent layer 12 to flexibly deform in response to the wearer's body movements when the pad 1 is worn, improving fit. Furthermore, absorbed excreted liquid can be dispersed in the front-to-back and left-to-right directions along the slits 18, allowing the absorbent core 132 to absorb and retain excreted liquid over a wide area. As will be described in detail later, the slits 18 are formed by cutting the non-skin-side of the absorbent layer 13 in the thickness direction using a cutter or the like. Therefore, in the pad 1 of this embodiment, slits (cuts) are formed in at least the non-skin-side sheet 133.

[0044] The slits 18 include a first slit 18a extending along the width direction and a second slit 18b extending along the front-rear direction. Here, "a slit extending along the width direction" refers to a slit where the smaller of the angles between the slit (or a tangent to the slit) and the width direction is 45 degrees or less. That is, the first slits 18a include slits that are parallel to the width direction and slits that are tilted at a predetermined angle of 45 degrees or less with respect to the width direction. Similarly, "a slit extending along the front-rear direction" refers to a slit where the smaller of the angles between the slit (or a tangent to the slit) and the front-rear direction is less than 45 degrees. That is, the second slits 18b include slits that are parallel to the front-rear direction and slits that are tilted at a predetermined angle of less than 45 degrees with respect to the front-rear direction.

[0045] The compressed portions 19 are portions that compress the absorbent layer 13 (skin-side sheet 131, absorbent core 132, and non-skin-side sheet 133) and the auxiliary absorbent layer 12 in the thickness direction, and are formed, for example, by stacking the absorbent layer 13 and the auxiliary absorbent layer 12 in the thickness direction and embossing them (see Figure 4). The presence of the compressed portions 19 compresses the multiple fibers that make up the absorbent layer 13 and the auxiliary absorbent layer 12 together, making it easier for the absorbent layer 13 and the auxiliary absorbent layer 12 to maintain their respective shapes and less likely to come apart. Therefore, when the wearer moves while wearing the pad 1, the absorbent layer 13 is prevented from losing its shape or twisting, which could result in a poor fit or leakage of excrement.

[0046] The absorbent layer 13 and the auxiliary absorbent layer 12 are only bonded together by the compressed portion 19, and are not fixed with adhesive or the like. Therefore, when the pad 1 is flushed down the toilet after use, if the compressed portion 19 becomes wet, the bond between the fibers (hydrogen bonds) will be released, and the fibers that make up the absorbent layer 13 and the auxiliary absorbent layer 12 will easily fall apart. This improves water-disintegrability (water-dispersibility), making it less likely to cause problems such as clogging the toilet pipes.

[0047] The absorbent core 132 of this embodiment also contains pulp fibers (absorbent fibers) made from broad-leaved trees (hardwood pulp). These hardwood absorbent fibers are characterized by shorter fiber length and smaller fiber diameter than softwood absorbent fibers (softwood pulp) made from softwood.

[0048] Figure 6 shows the fiber length distribution of hardwood water-absorbent fibers (hardwood pulp) and softwood water-absorbent fibers (softwood pulp). The horizontal axis shows fiber length (mm), and the vertical axis shows frequency (%). As shown in Figure 6, the average fiber length of softwood pulp is about 2.5 mm, and the fiber length distribution is wide (including fibers 3 mm or longer; standard deviation is 1.6). In contrast, the average fiber length of hardwood water-absorbent fibers is about 0.79 mm, and the fiber length distribution is narrow (standard deviation is 0.27).

[0049] The average fiber length of pulp fibers refers to 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 using a Kajaani FiberLab 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, conforming to the non-polarized light method).

[0050] The absorbent core 132 is constructed of short-fiber absorbent fibers (with an average fiber length of approximately 0.8 mm) such as hardwood pulp, thereby providing high water retention. For example, when comparing an absorbent core made of short-fiber hardwood pulp with an absorbent core made of long-fiber softwood pulp at the same weight, the fiber density of hardwood pulp is higher than that of softwood pulp. In other words, the use of hardwood pulp allows for a higher density of the absorbent core 132 compared to when softwood pulp is used. Furthermore, by increasing the density of the absorbent core 132, the capillary effect can be enhanced, improving water retention. The fiber density corresponds to the average number of fibers per unit area and is a value calculated by adding the fiber thickness and the average fiber spacing to the number of fibers per unit area in the case of a close-packed structure.

[0051] <Method of manufacturing interlabial pad 1> Next, a method of manufacturing the interlabial pad 1 will be described. Fig. 7 is a flow chart showing the manufacturing process of the pad 1 according to this embodiment. Fig. 8 is a schematic diagram showing a manufacturing apparatus 500 for manufacturing absorbent articles such as the pad 1. Note that Figs. 7 and 8 explain typical steps involved in manufacturing the pad 1, and do not show all of the manufacturing steps.

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

[0053] The manufacturing process of the pad 1 begins with a conveying step (S101) in which a continuous body of the non-skin side sheet 133 constituting the absorbent layer 13 is conveyed in the conveying direction. Note that in the manufacturing apparatus 500, the conveying direction is the direction along the front-to-rear direction of the pad 1. Hereinafter, the conveying direction will also be referred to as the "MD direction (Machine Direction)," and the direction perpendicular to the conveying direction (the direction along the width direction of the pad 1, i.e., the direction into the paper in FIG. 8 ) will also be referred to as the "CD direction (Cross Direction)."

[0054] In the conveying step, a continuous non-skin-side sheet web 133a (substrate sheet) in which the non-skin-side sheets 133 are connected in the MD direction is unwound from a raw roll and then conveyed from the upstream side to the downstream side in the MD direction at a predetermined conveying speed by a conveying mechanism 510 including a conveying roller or the like. Then, while the continuous non-skin-side sheet web 133a is being conveyed, steps S102 to S110 are performed, thereby manufacturing the pad 1.

[0055] Next, an absorbent core lamination step is performed (S102), in which absorbent cores 132 are laminated on the non-skin side sheet continuous web 133a (substrate sheet) being transported in the MD direction using an absorbent core lamination mechanism 520. The absorbent core lamination mechanism 520 has a defibrator 521, a material supply unit 522, and a rotating drum 523.

[0056] FIG. 9 is a flow chart showing the operations (steps) specifically performed in the absorbent core lamination step (S102). The absorbent core lamination step begins with a defibration step (S201) in which a pulp sheet is defibrated to produce pulverized pulp, which serves as the raw material for the absorbent core 132. The pulverized pulp is produced by pulverizing a pulp sheet PS1 using a defibration device 521. The defibration device 521 is provided with a garnet cylinder 521m. In this embodiment, the pulp sheet PS1, which serves as the raw material for forming the absorbent core 132, is primarily made of pulp containing hardwood pulp, as described above, but may also contain softwood pulp or be a pulp-mixed spunlace.

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

[0058] For example, the saw blade 525 of this embodiment has a plurality of blades, each 0.8 mm thick and 7 mm high, arranged at a pitch of approximately 12.7 mm in the MD direction (see FIG. 10B), and the saw blades 525 are attached to the circumferential surface 521mf of the garnet cylinder 521m at a pitch of approximately 5 mm along the CD direction (see FIG. 10C). With the saw blades 525 attached, the outer diameter of the garnet cylinder 521m (the diameter of the garnet cylinder 521m including the cutting edge of the saw blade 525) is approximately 450 mm to 500 mm. However, the above dimensions are merely examples and can be changed as appropriate depending on conditions such as the configuration and arrangement space of the defibration device 521.

[0059] During defibration, the garnet cylinder 521m is rotated so as to scrape the surface of the pulp sheet PS1 unwound from the raw roll with a saw blade 525, thereby finely pulverizing the pulp sheet PS1 and producing pulverized pulp. In this embodiment, defibration is performed using a feed roll 526 disposed opposite the garnet cylinder 521m in the MD direction as shown in Figure 11. The feed roll 526 is a rotating body that can rotate while supporting the pulp sheet PS1 on its circumferential surface, for example, by a nip mechanism (not shown).

[0060] 11, the clearance (distance in the MD direction) between the peripheral surface of the feed roll 526 and the cutting edge of the saw blade 525 provided on the garnet cylinder 521m is adjusted to, for example, about 0.5 mm. The feed roll 526 is rotated while supporting the pulp sheet PS1, and the garnet cylinder 521m is rotated at a predetermined speed in the opposite direction to the feed roll 526 while feeding the pulp sheet PS1 toward the garnet cylinder 521m. The pulp sheet PS1 is then defibrated at the point where the peripheral surface of the feed roll 526 and the cutting edge of the garnet cylinder 521m (saw blade 525) are closest to each other, producing pulverized pulp.

[0061] Using the garnet cylinder 521m of this embodiment, the amount of pulp sheet PS1 per unit width per unit time is 7.5 to 60 kg / hr, preferably 9.0 to 55 kg / hr. For example, assuming that the maximum pulp rate per unit time is 60 kg / hr, the diameter d of the saw blade 525 of the garnet cylinder 521m including the cutting edge is 470 mm, the rotation speed is 2000 rpm, and the feed rate of the pulp sheet P1 (525 mm width in the CD direction) in the MD direction is 2.66 m / min, and the axial advance distance (lead) of the spirally wound saw blade 525 is 20 mm when the garnet cylinder 521m makes one rotation (=3.14 d), each blade of the saw blade 525 will shave 0.0114 mm of the pulp sheet P1 in the MD direction (the feed direction of the pulp sheet P1) with each cut. By finely pulverizing the pulp sheet P1 in this manner, it is possible to produce pulverized pulp of an appropriate size that does not contain fibrous agglomerates (NOTS), which will be described later.

[0062] 9, an absorbent core forming step (S202) is performed in which the absorbent core 132 is formed using the crushed pulp as a material, and a transfer step (S203) is performed in which the formed absorbent core 132 is transferred to a base sheet (here, a continuous non-skin side sheet 133a) being transported in the MD. In this embodiment, the absorbent core forming step (S202) and the transfer step (S203) are performed using a rotating drum 523.

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

[0064] The rotating drum 523 is a hollow cylindrical drum equipped with a suction mechanism (not shown) that draws air from the outside to the inside of the outer peripheral surface. Furthermore, a plurality of recesses 523r are formed at a predetermined pitch on the outer peripheral surface as molds into which the material for the absorbent core 132 is packed. When the rotating drum 523 rotates and the recesses 523r enter the material supply section 522, the suction mechanism causes the material for the absorbent core 132 (ground pulp) supplied from the material supply section 522 to accumulate (build up) in the recesses 523r. This forms the absorbent core 132 (S202).

[0065] Then, as the rotating drum 523 rotates and the recess 523r containing the absorbent core 132 material reaches the bottom of the drum, the absorbent core 132 material is released from the recess 523r and transferred onto the transported base sheet (non-skin side sheet continuous web 133a) (S203), which is then handed over to the next process. As a result, the absorbent core 132 is laminated on the skin side of the non-skin side sheet 133 (S103).

[0066] 7, the base sheet on which the absorbent core 132 is laminated is laminated with the continuous body 131a of the skin side sheet 131 as it is transported downstream in the conveying direction (MD) from the absorbent core lamination mechanism 520 (see FIG. 8), and reaches the auxiliary absorbent layer lamination mechanism 530 in a state in which the absorbent layer 13 has been formed. For simplicity of explanation, the skin side sheet 131 is not shown in the steps following FIG. 8.

[0067] Next, a sub-absorbent layer laminating step is performed in which the sub-absorbent layer 12 is laminated on the skin side of the absorbent layer 13 in the thickness direction by the sub-absorbent layer laminating mechanism 530 (S103). The sub-absorbent layer laminating mechanism 530 has a defibrator 531. The defibrator 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 with reference to FIG. 10 etc. The defibrator 531 rotates in a manner to scrape the pulp sheet PS2 unwound from the raw roll, thereby pulverizing the pulp sheet PS2 to produce ground pulp, which is the raw material for the sub-absorbent layer 12. The ground pulp is sprayed directly on the base sheet, and a layer of ground pulp (the sub-absorbent layer 12) is laminated on the skin side of the absorbent layer 13.

[0068] The pulp sheet PS2 used in the auxiliary absorbent layer lamination step contains softwood pulp and may also contain hardwood pulp or rayon. The hardwood pulp content of the pulp sheet PS2 is lower than that of the pulp sheet PS1. This results in the auxiliary absorbent layer 12 having a longer average fiber length and a larger average fiber diameter than the absorbent core 132.

[0069] After the auxiliary absorbent layer 12 is laminated on the absorbent layer 13, an embossing process is carried out to form compressed portions 19. This causes the multiple fibers constituting the absorbent layer 13 and the auxiliary absorbent layer 12 to be compressed together, so that the laminated layers do not easily peel off or lose their shape.

[0070] Next, an inversion step is performed in which the base sheet (the absorbent layer 13 and the auxiliary absorbent layer 12) is inverted in the thickness direction by the inversion mechanism 540 (S104). In Fig. 8, the base sheet, which was transported from left to right on the paper, is inverted in the transport direction from right to left, and at the same time, the thickness direction is also inverted. Therefore, after the inversion step, the base sheet is transported in the MD with the absorbent layer 13 stacked vertically above the auxiliary absorbent layer 12.

[0071] Next, a first slit forming step is performed in which a first slit 18a is formed in the absorbent layer 13 using a first slit forming mechanism 550 (S105). The first slit forming mechanism 550 includes a cutter roll 551 and an anvil roll 552. The cutter roll 551 is a cylindrical roll having a plurality of blades on its peripheral surface, and is a rotating body that is driven to rotate about a rotation axis along the CD direction. The anvil roll 552 is disposed opposite the cutter roll 551 in the thickness direction (vertical direction in FIG. 8 ), and is a rotating body that is driven to rotate about a rotation axis along the CD direction. In this embodiment, as shown in FIG. 8 , the cutter roll 551 is provided on the upper side (non-skin side of the pad 1) of the manufacturing apparatus 500 in the vertical direction, and the anvil roll 552 is provided on the lower side (skin side of the pad 1). The cutter roll 551 and the anvil roll 552 sandwich and press the base sheet (the absorbent layer 13 and the auxiliary absorbent layer 12) in the thickness direction, thereby forming the first slit 18a.

[0072] 12A to 12C are diagrams illustrating the configuration of a cutter roll 551 used when forming the first slits 18a. FIG. 12A is a plan view of the cutter roll 551 as viewed from the MD direction. FIG. 12B is a diagram illustrating the arrangement pattern of multiple blades 551c provided on the circumferential surface 551f of the cutter roll 551. FIG. 12C is a cross-sectional view taken along the arrows D-D in FIG. 12B. Also, FIGS. 13A and 13B are diagrams illustrating the configuration of an anvil roll 552 used when forming the first slits 18a. FIG. 13A is a plan view of the anvil roll 552 as viewed from the MD direction. FIG. 13B is an enlarged view of 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 around a rotation axis Ar1 aligned in the CD direction. The cutter roll 551 has multiple blades 551c, 551c... protruding radially outward from the cylindrical peripheral surface 551f. The multiple blades 551c are arranged in the pattern shown in FIG. 12B , and the pattern shown in FIG. 12B is intermittently provided at a predetermined pitch along the circumferential direction on the peripheral surface 551f of the cutter roll 551 as shown in FIG. 12A . Each of the multiple blades 551c is configured to be able to form slits primarily along the CD direction (the width direction of the pad 1). That is, each blade 551c of the cutter roll 551 is primarily parallel to the CD direction or inclined at a predetermined angle of 45 degrees or less relative to the CD direction. These blades 551c can form multiple first slits 18a in the pad 1. However, the cutter roll 551 may also form some slits 18 aligned in the MD direction.

[0074] 13A, the anvil roll 552 of the first slit forming mechanism 550 is a cylindrical rotating body that rotates around a rotation axis Ar2 along the CD direction, and is disposed opposite the cutter roll 551 with the pad 1 (base sheet) sandwiched therebetween (see FIG. 8). As the anvil roll 552 and the cutter roll 551 rotate, a slit (incision) corresponding to the shape of the blade 551c is formed in the base sheet (in this embodiment, the absorbent layer 13, the auxiliary absorbent layer 12, etc.) sandwiched between them at a portion where a peripheral surface 552f of the anvil roll 552 and a tip of a blade 551c of the cutter roll 551 abut against each other.

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

[0076] 14 is a diagram illustrating the operation of forming the first slits 18a by the cutter roll 551 and the anvil roll 552. Fig. 14 shows 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 to each other at the center position CDCL in the CD direction.

[0077] As shown in Fig. 14 , there are overlapping portions between the blade 551c and the groove 552d on both sides of the central position CDCL in the CD direction. For example, in region F in Fig. 14 , the first portion np of the blade 551c of the cutter roll 551 located in the central portion in the CD direction overlaps with the groove 552d of the anvil roll 552. On the other hand, the second portions cp of the blade 551c located at both ends in the CD direction do not overlap with the groove 552d. In other words, when the tip of the blade 551c of the cutter roll 551 abuts against the circumferential surface 552f of the anvil roll 552, the second portion cp of the blade 551c abuts against the circumferential surface 552f, but the first portion np does not abut against the circumferential surface 552f.

[0078] In this case, the second portions cp of the blade 551c located at both ends in the CD direction press the base sheet (the absorbent layer 13, etc.) toward the peripheral surface 552f of the anvil roll 552, thereby forming the slits 18. On the other hand, the first portions np of the blade 551c located in the center in the CD direction press the base sheet (the absorbent layer 13, etc.) toward the grooves 552d of the anvil roll 552, and therefore do not form the slits 18. As a result, the first slits 18a along the width direction are formed such that the center in the CD direction (width direction) is divided (see the end regions SR in FIG. 5 ).

[0079] It is preferable that the boundary between the peripheral surface 552f and the groove 552d of the anvil roll 552 be chamfered. In FIG. 13B, the corner portion ch shown in black at the boundary between the peripheral surface 552f of the anvil roll 552 and the groove 552d is chamfered. By providing such a chamfered portion ch, the force applied by the blade 551c when pressed by the cutter roll 551 changes gradually at the boundary between the portion of the blade 551c of the cutter roll 551 that overlaps with the peripheral surface 552f of the anvil roll 552 in the CD direction (the second portion cp that forms the slit 18) and the portion that overlaps with the groove 552d (the first portion np that does not form the slit 18). Therefore, compared to when the chamfered portion ch is not present, the substrate is less likely to adhere to the blade 551c at the end of the slit 18. Furthermore, the chamfer at the boundary between the peripheral surface 552f and the groove 552d may be formed linearly as shown in FIG. 13B, or may be formed curvedly. In other words, the boundary between the peripheral surface 552f and the groove 552d may have a curved shape.

[0080] Next, a second slit forming step is performed in which a second slit 18b is formed in the absorbent layer 13 using a 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 cylindrical roll having a plurality of blades on its peripheral surface, and is a rotating body that is driven to rotate about a rotation axis along the CD direction. The anvil roll 562 is disposed opposite the cutter roll 561 in the thickness direction (vertical direction in FIG. 8 ), and is a rotating body that is driven to rotate about a rotation axis along the CD direction. In the second slit forming step, the second slit forming mechanism 560 cuts the base sheet (the absorbent layer 13 and the auxiliary absorbent layer 12) into a substantially elliptical shape as indicated by the dashed lines in FIG. 1 .

[0081] 15A to 15C are diagrams illustrating the configuration of a cutter roll 561 used when forming the second slits 18b. Fig. 15A is a plan view of the cutter roll 561 as viewed from the MD direction. Fig. 15B is a diagram illustrating the arrangement pattern of a plurality of blades 561c provided on a peripheral 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 around a rotation axis Ar3 aligned in the CD direction. It has multiple blades 561c, 561c... protruding radially outward from the cylindrical circumferential surface 561f. The multiple blades 561c are arranged in the pattern shown in FIG. 15B , and the pattern shown 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 multiple blades 561c is configured to form slits primarily along the MD direction (the front-to-rear direction of the pad 1). That is, the blades 561c of the cutter roll 561 are primarily parallel to the MD direction or inclined at a predetermined angle less than 45 degrees relative to the MD direction. These blades 561c can form multiple second slits 18b in the pad 1. However, the cutter roll 561 may also form slits 18 partially aligned in the CD direction.

[0083] Furthermore, a circumferential blade 561rc is provided on the peripheral surface 561f of the cutter roll 561 so as to surround the multiple blades 561c, 561c... along the MD direction. The circumferential blade 561rc is provided to match the shape of the outer edge of the auxiliary absorbent layer 12 (the roughly elliptical shape indicated by the dashed line in FIG. 1 ), and cuts out the sheet-like auxiliary absorbent layer 12 laminated in the auxiliary absorbent layer lamination step (S103) in a so-called die-cutting manner, thereby forming the auxiliary absorbent layer 12 into a roughly 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 disposed opposite the cutter roll 561 with the pad 1 (base sheet) sandwiched therebetween (see FIG. 8 ). Note that the circumferential surface of the anvil roll 562 does not have any depressions (grooves) corresponding to the grooves 552d of the anvil roll 552 (see FIG. 13 ). As the anvil roll 562 and the cutter roll 561 rotate, a slit (incision) corresponding to the shape of the blade 561c is formed in the base sheet (in this embodiment, the absorbent layer 13, the auxiliary absorbent layer 12, etc.) sandwiched between them at a portion where the circumferential surface of the anvil roll 562 abuts against the tip of the blade 561c of the cutter roll 561. At the same time, at the portion where the peripheral surface of the anvil roll 562 and the tip of the circumferential blade 561rc of the cutter roll 561 abut, the base sheet (absorbent layer 13 and auxiliary absorbent layer 12) sandwiched between them is cut out into an approximately elliptical shape along the shape of the circumferential blade 561rc.

[0085] Note that a portion of the blade 561c of the cutter roll 561 of the second slit forming mechanism 560 is disposed at a position that overlaps 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 portion of the second slit 18b formed in the second slit forming step (S106) is formed in a portion where the first slit 18a is not formed in the first slit forming step (S105) (a portion corresponding to the groove 552d of the anvil roll 552).

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

[0087] Next, a cutting and sealing process is performed in which the continuum 11a of the top layer 11 and the continuum 14a of the back layer 14, with the absorbent layer 13 and the auxiliary absorbent layer 12 sandwiched in the thickness direction, are cut into a predetermined shape and joined (sealed) using a cutting and sealing mechanism 570 (S107). In this cutting and sealing process, the continuum 11a of the top layer 11 and the continuum 14a of the back layer 14 are joined in a region outside the auxiliary absorbent layer 12 (absorbent layer 13) by a known welding method such as thermal welding or ultrasonic welding, or by an adhesive such as a hot melt adhesive. In other words, the top layer 11 and the back layer 14 are sealed in a region outside the area surrounded by the dashed line representing the auxiliary absorbent layer 12 in the flat state of the pad 1 shown in FIG. 1. The strip-shaped continuum 11a, 14a extending in the MD direction is then cut along the outer edge (contour) of the pad 1 to cut out individual pads 1.

[0088] Next, a sailing step (S108) is performed in which each pad 1 is folded along the front-to-back direction (MD) at the center of the width direction (CD) using a sailing mechanism 580. As shown in Fig. 3B, the sailing mechanism 580 folds the pad 1 along a fold line F along the front-to-back direction (MD) into a triangular shape that is convex toward the skin.

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

[0090] Next, a loosening process is performed in which the pad 1 (absorbent article) is loosened using a loosening mechanism 595 (S110). FIG. 16 is a diagram illustrating the configuration and operation of the loosening mechanism 595. The loosening mechanism 595 has multiple rollers 595a to 595e and two belts 595B1 and 595B2 that transport the pad 1 in the MD direction while sandwiching it between the upper and lower rollers. In FIG. 16, five rollers are provided from upstream to downstream in the MD direction: a first roller 595a, a second roller 595b, a third roller 595c, a fourth roller 595d, and a fifth roller 595e. Belts 595B1 and 595B2 are wound around each roller. The pad 1 is passed between these rollers 595a to 595e in the conveying direction and curved to one side and the other in the thickness direction along the circumferential surface of the rollers, thereby loosening and equalizing the uneven distribution and intertwining of the pulp fibers that make up the absorbent layer 13. 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 changed as appropriate depending on the product specifications of the pad 1, the configuration of the manufacturing apparatus 500, etc.

[0091] In the loosening mechanism 595, two rollers arranged adjacent to each other in the MD direction are arranged at positions offset in the up-down direction. More specifically, as shown in Fig. 16 , the rollers are arranged so that the position furthest up-down in the portion where the circumferential surface of the first roller 595a abuts against the pad 1 (the position of point P below the first roller 595a in Fig. 16 ) is located to one side in the up-down direction (lower) of the position furthest up-down in the portion where the circumferential surface of the second roller 595b abuts against the pad 1 (the position of point Q above the second roller 595b in Fig. 16 ).

[0092] With this configuration, the pad 1, conveyed in the MD direction, wraps around the circumferential surfaces of the rollers as it passes through them, curving to one side and the other in the thickness direction. For example, in FIG. 16 , when the pad 1 wraps around the circumferential surface of the first roller 595a, it curves significantly downward (to one side in the thickness direction), and when the pad 1 wraps around the circumferential surface of the second roller 595b, it curves significantly upward (to the other side in the thickness direction). This allows the absorbent layer 13 and the auxiliary absorbent layer 12 to flexibly deform, improving the fit of the pad 1 when worn. Furthermore, the correction of pulp fiber imbalance improves liquid absorption and liquid diffusion, and the curvature of the absorbent layer 13 and other layers in the thickness direction facilitates the opening of the slits 18 formed in the absorbent layer 13.

[0093] The loosening mechanism 595 may be modified as follows. FIG. 17 is a diagram illustrating a modified example of the loosening mechanism 595. In the loosening mechanism 595 shown in FIG. 17, the vertical spacing between adjacent rollers 595a to 595e in the MD direction is narrower than in the case of FIG. 16, and the pad 1 is conveyed by being sandwiched between the adjacent rollers. In FIG. 17, the pad 1 is curved to 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. Furthermore, by satisfying the positional relationship between points P and Q described above, the pad 1 can be efficiently loosened.

[0094] After the loosening process, the pads 1 are individually packaged downstream in the MD direction, and shipped as interlabial pad packages packed one by one or in multiple units, and distributed to the market.

[0095] <Regarding the Pulp Constituting the Absorbent Core 132> As described above, the absorbent core 132 of the pad 1 is formed from pulverized pulp obtained by defibrating the pulp sheet PS1 containing hardwood pulp in the defibration step (S201). That is, the shape and size of the pulp fibers constituting the absorbent core 132 are greatly affected by the degree of defibration of the pulp sheet PS1 in the defibration step. In this embodiment, defibration is performed using a garnet cylinder 521m shown in Fig. 10, thereby producing an absorbent core 132 (pulp fibers) with good water-decomposability and shape stability.

[0096] The absorbent core 132 of this embodiment is formed to have a length in the front-to-rear direction of 50 to 120 mm and an average basis weight of 50 to 120 gsm. This allows the pad 1 to fit securely around the wearer's vaginal opening when worn, while also providing a good feel against the skin and liquid absorbency. The absorbent core 132 of this embodiment contains multiple types of pulverized pulp (pulp fibers) with different lengths and shapes.

[0097] Conventionally, ground pulp (pulp fibers) forming absorbent cores can be classified into three types of forms produced during the defibration process: fiber clumps consisting of relatively long pulp fibers aggregated in a fluffy ball shape (hereinafter also referred to as "NOTS"), fibers short enough not to be entangled with other fibers (hereinafter also referred to as "FINE"), and fibers longer than FINE but shorter than NOTS (hereinafter also referred to as "ACCEPT").

[0098] If the absorbent core contains a high content of NOTS among these three types of fibers, it may feel worse against the skin when worn and may be less likely to disintegrate in water when disposed of in the toilet after use. Furthermore, if the FINE content is high, the fibers may become less intertwined, making it difficult for the absorbent core to maintain its shape stably, or the fibers may break apart during use, resulting in poor water retention. Therefore, in order to improve the shape stability, water retention, and water disintegrability of the absorbent core, it is preferable to increase the ACCEPT content as much as possible in the fibers constituting the absorbent core.

[0099] However, the absorbent cores used in conventional absorbent articles tend to have a high content of NOTS and FINE particles during the process of defibrating the pulp sheet, making it difficult to achieve both good water-disintegrability and shape stability.

[0100] In contrast, the absorbent core 132 manufactured using the manufacturing apparatus 500 of this embodiment can have a lower NOTS and FINE content than conventional absorbent cores. Fig. 18 is a diagram showing data comparing the NOTS, FINE, and ACCEPT content of the absorbent core 132 formed using the manufacturing apparatus 500 of this embodiment with that of an absorbent core formed using a conventional manufacturing method. Fig. 19 is a diagram illustrating a method for determining the NOTS, FINE, and ACCEPT content of an absorbent core (crushed pulp).

[0101] The content ratios of NOTS, FINE, and ACCEPT in pulverized pulp are determined by conducting an evaluation test of the pulverized pulp in accordance with the "Sieving Test Method for Chemical Products" specified in JIS K 0069-1992. In this embodiment, the evaluation test is conducted using a pulverization evaluation tester 300 (e.g., a pulp pulverization evaluation tester manufactured by Nissin Kikai Co., Ltd.) as shown in FIG. 19 . The pulverization evaluation tester 300 includes first to fifth sieves 311 to 315 and a vibration device 320. The first to fifth sieves 311 to 315 are sieves each equipped with wire mesh (e.g., a metal sieve specified in JIS Z 8801) with different mesh sizes (25.4 mm apart). In the crushing evaluation tester 300, various meshes are arranged in order from the top in the vertical direction: a 42 mesh sieve as the first sieve, a 4.7 mesh sieve as the second sieve, a 7.5 mesh sieve as the third sieve, a 14 mesh sieve as the fourth sieve, and a 60 mesh sieve as the fifth sieve. The vibration device 320 is a device that applies vibrations to the sieves 311 to 315.

[0102] The evaluation test of pulverized pulp was conducted on the absorbent core 132 manufactured by the manufacturing apparatus 500 of this embodiment, and on absorbent cores 1 to 3 manufactured by a conventional manufacturing method as comparative examples. In Comparative Examples 1 to 3, the pulp was defibrated using a conventional saw mill as the defibrating device. In Comparative Example 1, defibration was performed at a grinding amount (kg / hm) similar to that of this embodiment. In Comparative Example 2, the grinding amount was twice that of Comparative Example 1, and in Comparative Example 3, the grinding amount was three times that of Comparative Example 1.

[0103] When conducting an evaluation test of pulverized pulp, first, set the vibration device 320 (strength setting dial: 70, time setting: 5 minutes, vibration: continuous), and then loosen the pulverized pulp to be evaluated and place it on the second sieve 312. The pulverized pulp to be evaluated is approximately 5 mg, and its exact weight is measured in advance. Next, the first sieve 311 is placed on the device and secured with a clamp unit, and the vibration device 320 is operated. Next, after operating for 5 minutes, the clamp unit is loosened and the first sieve 311 is removed.

[0104] At this time, the pulverized pulp remaining on the second sieve 312 to the fourth sieve 314 is called NOTS. That is, fibers that do not pass through a 14-mesh or larger sieve are called NOTS and their weight is measured. In addition, the pulverized pulp that does not remain on any of the sieves 312 to 315 is called FINE. That is, fibers that pass through a 60-mesh sieve are called FINE and their weight is measured. In addition, the other pulverized pulp is called ACCEPT. That is, fibers that pass through the second sieve 312 to the fourth sieve 314 but do not pass through the fifth sieve 315 are called ACCEPT. This test is repeated multiple times (for example, two or more times) to calculate the average weight for each of NOTS, FINE, and FINE. The content of each fiber is then calculated from the weight ratio relative to the total weight (5 mg) of the pulverized pulp to be evaluated.

[0105] As a result of these pulverized pulp evaluation tests, Comparative Examples 1 to 3 all contained 14% or more NOTS. The content of NOTS increased as the amount of defibration per unit time increased. Comparative Examples 1 to 3 also contained 11% to 12% FINE (see FIG. 18). In contrast, it was revealed that the pulverized pulp constituting the absorbent core 132 of this embodiment did not contain NOTS. The FINE was 19% and the ACCEPT was 81% (see FIG. 18).

[0106] The absorbent core 132 of this embodiment has a low NOTS content, which prevents large fiber clumps from remaining undissolved in water, and the fibers constituting the absorbent core 132 are more likely to break down into smaller pieces when disposed of in a toilet, etc. At least, the weight ratio of NOTS to the total weight is 10% or less, which results in higher water-decomposability compared to when the weight ratio of NOTS is greater than 10%. Furthermore, the absorbent core 132 of this embodiment contains FINE fibers at a content ratio of 20% or less of the total weight, and more than 80% of the pulp fibers (ground pulp) constituting the absorbent core 132 are more likely to intertwine with each other. In other words, when the weight ratio of FINE fibers to the total weight is 20% or less, the pulp fibers are more likely to intertwine with each other, and the shape of the absorbent core 132 is more likely to be stably maintained compared to when the weight ratio is greater than 20%. Therefore, it is possible to manufacture an absorbent core 132 that maintains a stable shape when worn (in use) and that is highly water-decomposable and easy to disintegrate when disposed of in the toilet after use.

[0107] Furthermore, in the defibration step (S201) of this embodiment, the pulp sheet P1 is defibrated so that the defibration amount per unit width is 7.5 to 60 kg / mh. When using short-fiber hardwood pulp, the absorbent core may become compacted when the pulverized pulp is deposited (accumulated) in the recess 523r of the rotating drum 523, making it difficult to transfer to the base sheet. However, under the above conditions, the absorbent core 132 can be easily transferred to the base sheet (non-skin side sheet continuum 133a) while maintaining its shape. Note that, in the defibration step, increasing the defibration amount per unit time (increasing the rotation speed of the garnet cylinder 521m) may increase the proportion of NOTS, while conversely, decreasing the defibration amount per unit time (decreasing the rotation speed of the garnet cylinder 521m) may increase the proportion of FINE. Therefore, it is preferable to manufacture the absorbent core 132 within the above defibration amount range.

[0108] Furthermore, in the defibration step (S201) of this embodiment, a garnet cylinder 521m with a saw blade 525 wound around the circumferential direction of a rotating roll is used to defibrate a pulp sheet P1 containing hardwood pulp. By pulverizing the pulp sheet P1 with the saw blade 525 having many fine teeth, it is easier to form finer pulp than when defibration is performed using a conventional saw mill or hammer mill. In particular, since it is possible to reduce the proportion of NOTS (nots) and increase the proportion of ACCEPT (accepts) of a moderate size, this method is suitable for producing an absorbent core 132 with high water decomposability.

[0109] Furthermore, the absorbent core 132 of this embodiment does not contain NOTS. As mentioned above, the inclusion of NOTS can easily impair water-disintegrability, potentially making the absorbent core 132 less likely to decompose when flushed down the toilet. Furthermore, the inclusion of NOTS can create areas where the fiber density is locally high, making it difficult to achieve uniform water absorption and water retention, which may lead to issues such as excrement leakage. In contrast, the absorbent core 132 of this embodiment does not contain NOTS, making it possible to achieve an absorbent core 132 with good water absorption, water retention, and water-disintegrability.

[0110] Furthermore, from the viewpoint of the water-disintegratability of the absorbent core 132, it is desirable that the numerous pulp fibers (ground pulp) constituting the absorbent core 132 easily come into contact with water and easily disintegrate from their entangled state when the pad 1 is flushed down a toilet after use. In the manufacturing method of this embodiment, multiple slits 18 are formed in the absorbent core 132 (absorbent layer 13) in the slit forming steps (S105, S106). This makes it easier for water to be drawn into the absorbent core 132 through the slits 18 when the pad 1 is flushed down a toilet, facilitating contact of the pulp fibers with water. Furthermore, because the pulp fibers are loosened in the loosening step (S110), water can easily permeate the entire absorbent core 132 evenly. Therefore, an absorbent core 132 with good water-disintegratability can be manufactured.

[0111] Furthermore, the loosening step (S110) is performed after the slit forming steps (S105, S106). By performing the steps in this order, each of the multiple slits 18, 18... formed in the absorbent core 132 in the slit forming step is more likely to widen during the loosening step (the cuts are more likely to open). This allows water to more easily penetrate through the slits 18 (cuts) when the pad 1 is flushed down the toilet, making it easier for water to reach the inside of the absorbent core 132. This facilitates contact between water and the pulp fibers that make up the absorbent core 132, further improving water-decomposability.

[0112] In the loosening process, the pad 1 is conveyed while being curved by wrapping around the circumferential surfaces of the plurality of rollers provided in the loosening mechanism 595. For example, in FIG. 16 , the pad 1 is supported between belts 595B1 and 595B2. First, the pad 1 is wrapped around the lower circumferential surface of the first roller 595a, which rotates around a rotation axis along the CD direction, and is curved downward to form a large convex shape. The pad 1 is then conveyed to the second roller 595b, where it is wrapped around the upper circumferential surface of 595b, and is curved upward to form a large convex shape. In other words, the lowest position (point P in FIG. 16 ) of the portion where the circumferential surface of the first roller 595a contacts 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 contacts the pad 1, so that the pad 1 is curved upward and downward (in the thickness direction) along the circumferential surfaces of these rollers.

[0113] As illustrated in FIG. 5 , the absorbent core 132 has a plurality of first slits 18a extending along the width direction (CD direction) and a plurality of second slits 18b extending along the front-rear direction (MD direction). During the disintegration process, the pad 1 (absorbent core 132) is conveyed in the MD direction and curved in the thickness direction, causing the first slits 18a extending along the CD direction (width direction) to expand or contract along the circumferential surface of the roller (corresponding to the MD direction). The second slits 18b extending along the MD direction (front-rear direction) to expand or contract based on the thickness of the absorbent core 132 and the difference in speed between the inner and outer peripheries as the pad passes over the circumferential surface of the roller. This allows each of the plurality of slits 18, 18 to open easily. When the used pad 1 is discarded in a toilet or the like, water is drawn in through the open slits 18, further enhancing the water-decomposability of the absorbent core 132.

[0114] Furthermore, in the loosening process, the pad 1 is conveyed with its front-to-back direction aligned with the MD direction. As shown in FIGS. 1 and 5, the pad 1 is formed in a generally elliptical shape with its front-to-back direction longer than its width direction so as to fit the wearer's crotch. In other words, the pad 1 is conveyed with its length in the MD direction increased. This makes it easier for the pad 1 to bend significantly around the multiple rollers 595a to 595e provided in the loosening mechanism 595. For example, in FIG. 16, the pad 1 is wrapped around a wide area of ​​the upper half of the second roller 595b in the circumferential direction, resulting in a curve close to 180 degrees. In contrast, if the pad 1 were shorter in the MD direction, the area around which the pad 1 wraps around the second roller 595b in the circumferential direction would be narrower, resulting in a smaller degree of curvature than in the above-described case. In this embodiment, by transporting the pad 1 with the front-to-back direction aligned with the MD direction so that the length in the MD direction is longer, the pad 1 (absorbent core 132) can be efficiently curved in the loosening process.

[0115] In this case, the length L13 of the absorbent core 132 in the front-rear direction (MD direction) is preferably longer than twice the diameter of each roller (e.g., the diameter d595a of the first roller 595a). As described above, in order to efficiently curve the absorbent core 132 (pad 1) in the loosening process, it is desirable for the absorbent core 132 to be wound around as wide an area as possible in the circumferential direction of the roller. 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 front-rear direction (MD direction) is 1.57 times the diameter of the roller, the absorbent core 132 will theoretically be wound around half the area in the circumferential direction of the roller. Therefore, by making the length L13 of the absorbent core 132 in the front-to-rear direction (MD direction) longer than twice the diameter of the roller, the pad 1 can be more easily wrapped around the circumferential surface of the roller as shown in Figure 16, even taking into account errors during conveyance by the belts 595B1 and 595B2. This makes it easier to curve the pad 1 significantly, and makes the slits 18 more easily open. This can further improve water-disintegratability.

[0116] The loosening step (S110) is performed after the sailing step (S108). In the sailing step, the absorbent core 132 (pad 1) is folded in half at the center of the width direction (CD direction) along a folding line along the front-to-back direction (MD direction). That is, the absorbent core 132 is folded in thickness direction between the region on one side of the center of the width direction (CD direction) and the region on the other side, resulting in a thicker absorbent core 132, which is then transported in the MD direction. Then, downstream in the MD direction, when the absorbent core 132 curves along the circumferential surfaces of the rollers 595a-595d of the loosening mechanism 595, the thicker the absorbent core 132, the longer the distance from the center of rotation of the rollers in the radial direction, making it more likely to be pulled in the circumferential direction (MD direction) of the rollers. For example, in FIG. 16, the pad 1 along the circumferential surface of the second roller 595b is more likely to be pulled in the circumferential direction at point R, which is farther from the circumferential surface, than at point Q, where the pad 1 abuts the circumferential surface. In this case, the slits 18 provided near point R in the thickness direction are easier to open than the slits 18 provided near point Q. Therefore, by loosening the absorbent core 132, which has been folded in half and thickened in the sailing process, in the loosening process, the slits 18 become easier to open, thereby further improving water-decomposability.

[0117] Furthermore, it is preferable that the total length of the first slits 18a, 18a... provided in the absorbent core 132 is longer than the total length of the second slits 18b, 18b.... As explained above, in the disintegration process, the slits 18 are made easier to open by curving the absorbent core 132 in the thickness direction as it is transported along the MD. In this process, the first slits 18a along the CD direction are more likely to open than the second slits 18b along the MD. Therefore, if the total length of the first slits 18a is longer than the total length of the second slits 18b, the overall length over which the slits 18 are more easily opened is increased. In other words, a larger number of slits 18 can be opened efficiently. This improves the water-disintegrability of the absorbent core 132.

[0118] ===Other Embodiments= ...

[0119] In the above embodiment, the absorbent core 132 of the absorbent layer 13 is described as being composed of short fibers with an average fiber length of approximately 0.8 mm. Conventionally, when it is desired to finely grind pulp to shorten the fiber length, a softener (debonder) such as a quaternary ammonium surfactant is added to the pulp sheet before grinding to make the pulp easier to grind (so-called treated pulp). However, the use of a softener (debonder) may easily impair water absorption.

[0120] Therefore, it is preferable that the absorbent fibers constituting the absorbent core 132 of the pad 1 are formed without containing a softener (debonder), thereby preventing a decrease in the water retention performance of the absorbent core 132. In the above-described embodiment, the absorbent core 132 is formed using hardwood pulp, so that the average fiber length can be set to about 0.8 mm without using a softener (debonder), thereby realizing an absorbent core 132 with excellent water absorption and flexibility.

[0121] In the above embodiment, the pad 1 is described as being configured such that the absorbent layer 13 is disposed closer to the skin than the auxiliary absorbent layer 12 (see FIG. 2, etc.), but the arrangement of these layers in the thickness direction may be reversed. For example, the auxiliary absorbent layer 12 may be disposed on the side of the absorbent layer 13 that is closer to the skin in the thickness direction. Alternatively, the pad 1 may be configured to include only the absorbent layer 13, without the auxiliary absorbent layer 12.

[0122] LIST OF SYMBOLS 1 Interlabial pad (pad, absorbent article), 11 Surface layer, 11a Continuum, 12 Sub-absorbent layer, 13 Absorbent layer, 131 Skin side sheet, 131a Continuum, 132 Absorbent core, 133 Non-skin side sheet, 133a Continuum, 14 Back layer, 14a Continuum, 15 Finger insertion sheet, 15de Finger insertion sheet non-joined portion, 16 Finger insertion sheet jointed portion, 17 Back layer jointed portion, 18 Slit, 18a First slit, 18b Second slit, 19 Compression 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 apparatus, 510 conveying mechanism, 520 absorbent core lamination mechanism, 521 defibration device, 521m garnet cylinder, 521mf peripheral surface, 521Ar rotating shaft, 522 material supply section, 523 rotating drum, 523r recess, 525 saw blade, 526 feed roll, 530 auxiliary absorbent layer lamination mechanism, 531 defibration 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 peripheral blade, 562 anvil roll, 570 Cutting and sealing mechanism, 580: Sailer mechanism, 590: Finger insertion sheet attachment mechanism, 595: Refining mechanism, 595a: First roller, 595b: Second roller, 595c: Third roller, 595d: Fourth roller, F: Folding line (folding 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; 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 between 25.4 mm each, 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 pulp sheet is defibrillated in the defibrillation step in such a manner. A method for manufacturing an interlabial pad, characterized by this.

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. A method for manufacturing an interlabial pad, characterized by this.

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. A method for manufacturing an interlabial pad, characterized by this.

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. A method for manufacturing an interlabial pad, characterized by this.

5. The method for manufacturing an interlabial pad according to claim 1 or 2, further 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. A method for manufacturing an interlabial pad, characterized by this.

6. The method for manufacturing an interlabial pad according to claim 5, wherein the loosening step is performed after the slit forming step. A method for manufacturing an interlabial pad, characterized by this.

7. The method for manufacturing an interlabial pad according to claim 6, wherein 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 the interlabial pad along the conveyance direction while sandwiching it. 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 of the position of the portion of the circumferential surface of the second roller that contacts the interlabial pad on the other side. A method for manufacturing an interlabial pad, characterized by this.

8. The method for manufacturing an interlabial pad according to claim 7, wherein the absorbent core has a front-rear direction and a width direction, the length of the absorbent core in the front-rear direction is longer than the length in the width direction, and in the loosening step, the absorbent core is conveyed with the front-rear direction along the conveyance direction. A method for manufacturing an interlabial pad, characterized by this.

9. The method for manufacturing an interlabial pad according to claim 8, wherein the length of the absorbent core in the front-rear direction is longer than twice the diameter of the first roller. A method for manufacturing an interlabial pad, characterized by this.

10. The method for manufacturing an interlabial pad according to claim 8, further comprising a sealer step of folding the absorbent core in half along a fold line along the front-rear direction, and the loosening step is performed after the sealer step. A method for manufacturing an interlabial pad, characterized by this.

11. The method for manufacturing an interlabial pad 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-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. A method for manufacturing an interlabial pad, characterized by this.

12. A pudendal pad comprising 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 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 sieve of 60 mesh is 20% or less with respect to the total weight of the pulverized pulp to be evaluated. The pudendal pad is characterized by this.

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