Method of manufacturing an interlabial pad and interlabial pad

Abstract

The method for manufacturing an interlabial pad includes a defibrating step (S201) of defibrating a pulp sheet containing a broadleaf tree pulp to produce a ground pulp, and an absorbent core forming step (S202) of forming an absorbent core (132) by aggregating the ground pulp. In the defibrating step, the pulp sheet is defibrated so that, in a pulp ground state evaluation test in which the ground pulp is caused to pass through a plurality of screens having different mesh numbers at an interval of 25.4 mm, the proportion of the weight of fibers that do not pass through the screen (312 to 314) having a mesh number of 14 or more is 10% or less with respect to the total weight of the ground pulp serving as an evaluation target, and the proportion of the weight of fibers that pass through the screen (315) having a mesh number of 60 is 20% or less.

Description

Technical Field

[0001] This invention relates to a method for manufacturing an interlabial pad and the interlabial pad itself. Background Technology

[0002] Previously, absorbent articles such as interlabial pads, which are worn in close contact with the labia, were known. In such interlabial pads (absorbent articles), by providing multiple slits in a rigid component such as the absorbent body, it is easy to deform three-dimensionally along the contours of the wearer's body, thereby improving the fit during wear. For example, Patent Document 1 discloses an interlabial pad with multiple slits provided along the long and short sides of the product.

[0003] Existing technical documents

[0004] Patent documents

[0005] Patent Document 1: Japanese Patent Application Publication No. 2004-97693 Summary of the Invention

[0006] The problem that the invention aims to solve

[0007] In recent years, the following technology has attracted attention in such interlabial pads: by using pulp containing short-fibered hardwood pulp to form the absorbent core, the hydrolysis of the absorbent core can be improved, allowing it to dissolve easily in water and disperse readily when flushed down the toilet after use. However, in conventional manufacturing methods, the defiberization of the hardwood pulp results in a large number of large fiber clumps (bulk fibers) and excessively fine fibers (fine fibers), making it difficult to manufacture an absorbent core that balances good hydrolysis and shape stability.

[0008] The present invention was made in view of the aforementioned problems, and its object is to provide an interlabial pad having an absorbent core with good hydrolysis properties and shape stability.

[0009] Methods for solving problems

[0010] The main technical solution for achieving the above-mentioned objective is a method for manufacturing an interlabial pad, which is a method for manufacturing an interlabial pad having an absorbent core. The method is characterized by comprising: a defibering step, in which pulp sheets containing broadleaf pulp are defibered to produce pulverized pulp; and an absorbent core forming step, in which the pulverized pulp is aggregated to form the absorbent core. In the defibering step, the pulp sheets are defibered so that, in the case of a pulp pulverization state evaluation test on the pulverized pulp, in which the pulp passes through various sieves with different mesh sizes (25.4 mm spacing), the proportion of the weight of fibers that did not pass through a sieve of 14 mesh or larger relative to the total weight of the pulverized pulp being evaluated is 10% or less, and the proportion of the weight of fibers that passed through a sieve of 60 mesh relative to the total weight of the pulverized pulp being evaluated is 20% or less.

[0011] Other features of the invention will become clear from the description and drawings herein.

[0012] Invention Effects

[0013] According to the present invention, it is possible to provide an interlabial pad having an absorbent core with good hydrolysis properties and shape stability. Attached Figure Description

[0014] Figure 1 This is a top view of pad 1 in its unfolded state.

[0015] Figure 2 yes Figure 1 A rough cross-sectional view of the AA direction.

[0016] Figure 3 is a diagram illustrating the structure of pad 1.

[0017] Figure 4 This is a diagram illustrating the structure of pad 1.

[0018] Figure 5 This is a top view illustrating the structure of the absorption layer 13.

[0019] Figure 6 It is a diagram showing the distribution of fiber lengths in hardwood absorbent fibers (hardwood pulp) and softwood absorbent fibers (softwood pulp).

[0020] Figure 7 This is a flowchart showing the manufacturing process of pad 1.

[0021] Figure 8 This is a schematic diagram illustrating a manufacturing apparatus 500 for manufacturing absorbent articles such as pad 1.

[0022] Figure 9This is a flowchart showing the specific actions (processes) performed in the absorbent core stacking process (S102).

[0023] Figures 10A-10C This is a diagram illustrating the structure of the 521m sawtooth cylinder.

[0024] Figure 11 This diagram illustrates the method of defiberizing PS1 pulp sheets using a serrated cylinder 521m.

[0025] Figures 12A-12C This is a diagram illustrating the structure of the cutting roller 551 used in forming the first slit 18a.

[0026] Figures 13A-13B This is a diagram illustrating the structure of the anvil roller 552 used in forming the first slit 18a.

[0027] Figure 14 This diagram illustrates the action of forming the first slit 18a using the cutting roller 551 and the anvil roller 552.

[0028] Figures 15A-15C This is a diagram illustrating the structure of the cutting roller 561 used in forming the second slit 18b.

[0029] Figure 16 This is a diagram illustrating the structure and operation of the disassembly mechanism 595.

[0030] Figure 17 This is a diagram illustrating a variation of the disassembly mechanism 595.

[0031] Figure 18 is a graph showing data comparing the proportions of NOTS (bulk fibers), FINE (fine fibers), and ACCEPT (qualified fibers) in the absorbent core 132 formed by the manufacturing apparatus 500 and the absorbent core formed by a conventional manufacturing method.

[0032] Figure 19 This is a diagram illustrating the method for determining the proportions of NOTS (clumped fibers), FINE (fine fibers), and ACCEPT (qualified fibers) contained in absorbent core (pulverized pulp). Detailed Implementation

[0033] Based on the description in this specification and the accompanying drawings, at least the following will become clear.

[0034] (Option 1)

[0035] A method for manufacturing an interlabial pad, characterized in that the method comprises: a defibering step in which pulp sheets containing broadleaf pulp are defibered to produce pulverized pulp; and an absorbent core forming step in which the pulverized pulp is aggregated to form the absorbent core. In the defibering step, the pulp sheets are defibered so that, in the case of a pulp pulverization state evaluation test on the pulverized pulp, the proportion of fibers that do not pass through a sieve of 14 mesh or larger relative to the total weight of the pulverized pulp being evaluated is 10% or less, and the proportion of fibers that pass through a sieve of 60 mesh or smaller relative to the total weight of the pulverized pulp being evaluated is 20% or less.

[0036] According to the manufacturing method of the labial pad in Scheme 1, the proportion of larger fiber clumps (NOTS) that do not pass through a sieve of 14 mesh or larger is as low as 10% or less. Therefore, compared to the opposite case, it is easier to prevent fiber clumps from remaining in water without disintegrating. Furthermore, since the proportion of finer fibers (FINE) that pass through a sieve of 60 mesh is as low as 20%, compared to the opposite case, the fibers are more likely to entangle with each other, thus easily maintaining the shape of the absorbent core. Therefore, it is possible to manufacture a labial pad with an absorbent core that is shape-stable when worn and has high hydrolyticity and easily disintegrates when flushed down the toilet or similar surfaces after use.

[0037] (Option 2)

[0038] According to the method for manufacturing interlabial pads as described in Scheme 1, the characteristic is that, in the defibering process, the defibering amount per unit width of the pulp sheet is 7.5~60.0 kg / mh.

[0039] According to the manufacturing method of the interlabial pad in Scheme 2, if the amount of defiber per unit time is increased in the defibering process, the proportion of NOTs may increase; if the amount of defiber per unit time is decreased, the proportion of FINE may increase. By defibering in a manner that satisfies the defibering amount of pulp fiber of 7.5~60 kg / mh, it is easy to transfer the absorbent core to the substrate sheet while maintaining its shape.

[0040] (Option 3)

[0041] The method for manufacturing interlabial pads according to any one of Schemes 1 to 2 is characterized in that, in the defibering process, a saw-tooth cylinder with a saw blade wound around the circumference of a rotating roller is used to defiber the pulp sheet.

[0042] According to the method for manufacturing interlabial pads in Scheme 3, the pulp flakes are pulverized using a saw blade with multiple finer blades. Compared to the conventional method of defiberization using a grinding saw or hammer mill, this method more easily produces finer pulverized pulp. In particular, because the proportion of NOTs can be reduced in the pulverized pulp, it is suitable for manufacturing absorbent cores with high hydrolytic properties.

[0043] (Option 4)

[0044] The method for manufacturing interlabial pads according to any one of Schemes 1 to 3 is characterized in that the pulverized pulp does not contain fibers that did not pass through the sieve of 14 mesh or larger during the pulp pulverization state evaluation test.

[0045] According to the manufacturing method of the labial pad in Scheme 4, since the absorbent core does not contain NOTES, it is difficult to create localized areas of increased fiber density, making it easier to achieve uniform absorbency and water retention. Furthermore, improved hydrolysis properties allow the absorbent core to easily decompose when flushed down the toilet. Therefore, it is possible to manufacture an absorbent core with excellent absorbency, water retention, and hydrolysis properties.

[0046] (Option 5)

[0047] The method for manufacturing an interlabial pad according to any one of Schemes 1 to 4 is characterized in that the method comprises: a conveying step in which the absorbent core is conveyed along a conveying direction; a slit forming step in which a slit is formed on the conveyed absorbent core; and a disassembly step in which the pulverized pulp constituting the absorbent core is disassembled.

[0048] According to the manufacturing method of the interlabial pad in Scheme 5, slits are formed on the absorbent core through a slit-forming process. Therefore, when the used interlabial pad is flushed down the toilet, water is easily introduced into the interior of the absorbent core through the slits, allowing the pulp fibers to easily come into contact with water. Furthermore, since the pulp fibers are unwound using a delamination process, water can easily and evenly penetrate throughout the entire absorbent core. Therefore, it is possible to manufacture an absorbent core with good hydrolytic properties.

[0049] (Option 6)

[0050] The method for manufacturing interlabial pads according to any one of Schemes 1 to 5 is characterized in that the unraveling process is performed after the slit formation process.

[0051] According to the manufacturing method of the interlabial pad in Scheme 6, the multiple slits formed in the absorbent core during the slit-forming process are easily expanded during the unpacking process. Therefore, when the used interlabial pad is flushed down the toilet, water easily seeps in through the slits and reaches the inside of the absorbent core. Consequently, the pulp fibers constituting the absorbent core easily come into contact with water, further improving hydrolysis properties.

[0052] (Option 7)

[0053] The method for manufacturing interlabial pads according to any one of Schemes 1 to 6 is characterized in that the unwinding process is performed as follows: while clamping the interlabial pad between the first roller and the second roller, it is conveyed along the conveying direction. The first roller rotates about a rotation axis orthogonal to the conveying direction. The second roller is arranged adjacent to the downstream side of the first roller in the conveying direction and rotates about a rotation axis orthogonal to the conveying direction. In the vertical direction, the position of the closest side of the portion of the circumference of the first roller that abuts against the interlabial pad is located one side further than the position of the closest side of the portion of the circumference of the second roller that abuts against the interlabial pad.

[0054] According to the manufacturing method of the labia pad in Scheme 7, during the unwinding process, the labia pad is conveyed along the conveying direction (MD direction) while being bent in the thickness direction to one side and the other side by wrapping it around the circumference of each roller, such as the first roller and the second roller. This causes the slits provided in the absorbent core to expand or contract. As a result, multiple slits can be easily opened, and when the used labia pad is thrown into the toilet, water can be easily introduced through the opened slits, further improving the hydrolytic properties of the absorbent core.

[0055] (Option 8)

[0056] The method for manufacturing a labial pad according to any one of Schemes 1 to 7 is characterized in that the absorbent core has a front-back direction and a width direction, the length of the absorbent core in the front-back direction is longer than the length in the width direction, and in the unwinding process, the absorbent core is conveyed with the front-back direction along the conveying direction.

[0057] According to the manufacturing method of the inter-labial pad in Scheme 8, by conveying the absorbent core in a state where its length in the MD direction increases, it is easy to wind the absorbent core over a large area of ​​the roller's circumference. That is, by winding the absorbent core as long as possible around the circumference of the roller, the absorbent core can be easily bent. As a result, the slit can be easily opened.

[0058] (Option 9)

[0059] The method for manufacturing a labial pad according to any one of Schemes 1 to 8 is characterized in that the length of the absorbent core in the front-back direction is longer than twice the diameter of the first roller.

[0060] According to the manufacturing method of the interlabial pad in Scheme 9, the absorbent core is easily wound around approximately half of the circumferential area of ​​the roller. Therefore, the absorbent core is more easily bent along the circumferential surface of each roller. This facilitates the opening of the slits, further improving hydrolytic properties.

[0061] (Option 10)

[0062] The method for manufacturing an interlabial pad according to any one of the embodiments 1 to 9 is characterized in that the method for manufacturing an interlabial pad further includes a folding step, in which the absorbent core is folded in half using a fold line along the front-back direction, and the unwrapping step is performed after the folding step.

[0063] According to the labial pad manufacturing method of Scheme 10, by using the unwrapping process to unwrap the absorbent core that has become thicker during the folding process, the slit can be opened more easily, thereby further improving hydrolytic properties.

[0064] (Option 11)

[0065] The method for manufacturing interlabial pads according to any one of Schemes 1 to 10 is characterized in that, in the slit forming process, a plurality of first slits along the width direction and a plurality of second slits along the front-back direction are formed, wherein the total length of the plurality of first slits is longer than the total length of the plurality of second slits.

[0066] According to the method for manufacturing the interlabial pad in Scheme 11, by bending the absorbent core conveyed along the MD direction in the thickness direction, the first slit along the CD direction is more easily opened than the second slit along the MD direction. Therefore, if the total length of the first slit is longer than the total length of the second slit, the length of the slit that is easier to open becomes longer as a whole. As a result, the hydrolytic properties of the absorbent core can be improved.

[0067] (Option 12)

[0068] An interlabial pad comprising an absorbent core having pulverized pulp obtained by defiberizing pulp flakes containing broadleaf pulp, characterized in that, in the case of a pulp pulverization state evaluation test on the pulverized pulp, wherein the weight of fibers that did not pass through a sieve of 14 mesh or larger relative to the total weight of the pulverized pulp being evaluated is 10% or less, and the weight of fibers that passed through a sieve of 60 mesh or larger relative to the total weight of the pulverized pulp being evaluated is 20% or less.

[0069] (Option 12)

[0070] According to the labial pad of Scheme 12, the proportion of larger fiber clumps (NOTS) that do not pass through a sieve of 14 mesh or larger is as low as 10%, thus, compared to the opposite case, it is easier to prevent fiber clumps from remaining in the water without disintegrating. Furthermore, since the proportion of finer fibers (FINE) that pass through a 60-mesh sieve is as low as 20%, compared to the opposite case, the fibers are more likely to entangle with each other, thus easily maintaining the shape of the absorbent core. Therefore, it is possible to achieve a labial pad with an absorbent core that is shape-stable when worn and has high hydrolyticity and easily disintegrates when disposed of in the toilet or similar containers after use.

[0071] ===Implementation Methods===

[0072] Hereinafter, the embodiment will be described using the interlabial pad 1 (hereinafter also referred to as "pad 1") as an example of the absorbent article of the present invention. The interlabial pad is a physiological product that is inserted between the labia of a woman to absorb excretions (body fluids) such as menstrual blood.

[0073] <Basic Structure of Interlabial Pad 1>

[0074] Figure 1 This is a top view of pad 1 in its unfolded state. Figure 1 This is a view taken from the skin side of pad 1. Figure 2 yes Figure 1 A schematic cross-sectional view from the AA direction. Figure 3 and Figure 4 This is a diagram illustrating the structure of pad 1. (Each diagram...) Figures 1-4 In the diagram, CC represents the center in the width direction, and CL represents the center in the front-to-back direction of the absorption layer 13 (described later) when viewing pad 1 along the thickness direction. Additionally, Figure 1 and Figure 2 The figure shows the state in which the finger is inserted into the central CC, the piece 15 (described later) is cut off, and the pad 1 is placed flat on the plane ("flat plane" state).

[0075] The pad 1 has mutually orthogonal front-back direction, width direction, and thickness direction. In the front-back direction of the pad 1, the side that is located on the wearer's abdomen when worn is designated as the "front side", and the side that is located on the wearer's back is designated as the "back side". In addition, in the thickness direction of the pad 1, the side that is in contact with the wearer's skin is designated as the "skin side", and the opposite side is designated as the "non-skin side".

[0076] like Figures 1-4 As shown, when viewed from above, pad 1 is an approximately elliptical shape, longer in the front-to-back direction than in the width direction, and symmetrical about its width center CC. It narrows inwards towards the width center CL, resulting in a narrower width. Furthermore, when viewed from above, pad 1 is asymmetrical about its width center. Specifically, the center CL (the center of the absorber layer 13 in the front-to-back direction) is located further back than the center of the pad 1 in the front-to-back direction, and the distance from the front end of pad 1 to the front end of absorber layer 13 is longer than the distance from the rear end of pad 1 to the rear end of absorber layer 13. That is, in the front-to-back direction of pad 1, absorber layer 13 is positioned further back. Figures 2-4 As shown, the pad 1 has a surface layer 11, a sub-absorbent layer 12, an absorbent layer 13, a back layer 14, and a finger insertion piece 15.

[0077] In this embodiment, pad 1 is stored and distributed as a product bent towards the non-skin side at fold line F. Figure 3 and Figure 4 This is a diagram illustrating the breakdown of pad 1 into its individual components. For example... Figure 3A As shown, in this embodiment, the pad 1 is bent towards the non-skin side at the fold line F (bending line) of the central portion (central CC) in the width direction. The finger insertion piece 15, which forms the finger insertion portion 20, is fixed to the position closest to the non-skin side using an adhesive such as hot melt adhesive HMA. The fold line F is a bend that runs along the front-back direction and is located at the central portion in the width direction. The fold line F is a portion with a predetermined width, and the apex of the fold line F on the skin side (the portion protruding most towards the skin) is located approximately at the same position as the central CC in the width direction. Figure 3B This is the state in which the finger insertion piece 15 is separated from the back layer 14. Figure 3C This is to change the pad 1 from a bent state at fold F to a horizontal state after the finger insertion piece 15 has been removed. Furthermore, from... Figure 3C From the state shown, as Figure 4 As shown, starting from the skin side in the thickness direction, a surface layer 11, a sub-absorbent layer 12, an absorbent layer 13, and a back layer 14 are sequentially overlapped, and at least a portion of the components are joined together by an adhesive or the like (see reference). Figure 2 ).

[0078] The surface layer 11 is located on the side closest to the skin and comes into contact with the wearer's skin (between the labia) during wear. Therefore, a soft sheet that is less likely to irritate the skin is preferred. The surface layer 11 forms the shape of the pad 1 and is a liquid-permeable sheet component. Examples of materials that can be used as the surface layer 11 include nonwoven fabrics obtained by manufacturing methods such as meltblowing, spunbonding, dot bonding, hot air, needle punching, dry / wet hydroentangling, and foam film, either individually or in combination. Sheet components made of fibers formed from materials composed of rayon, cellulose acetate, cotton, pulp, or synthetic resins (e.g., polyethylene terephthalate (PET), polypropylene (PP), polyethylene (PE), etc.) or composited in a manner that forms a core-sheath structure can be used. In this embodiment, the pad 1 uses a sheet component made of rayon and polyethylene terephthalate.

[0079] The sub-absorbent layer 12 is located on the non-skin side of the surface layer 11 and on the skin side of the absorbent layer 13. The sub-absorbent layer 12 acts as a buffer layer, softly conforming to the wearer's movements, changes in labial movement, and pressure from clothing between the surface layer 11 and the absorbent layer 13, thus reducing discomfort to the wearer. The sub-absorbent layer 12 is approximately elliptical in shape, smaller than the surface layer 11, and located approximately in the center (more precisely, towards the rear) of the pad 1. Furthermore, the sub-absorbent layer 12 narrows inward in the width direction at its central CL in the front-to-back direction, and its length in the width direction also narrows. For example, pulp, chemical pulp, rayon, acetate fiber, natural cotton, and synthetic fibers can be used alone or in combination as the sub-absorbent layer 12. In this embodiment, fibers obtained by mixing pulp fibers, rayon fibers, and polyethylene terephthalate (PET) are mainly used.

[0080] The absorbent layer 13 is located on the non-skin side of the sub-absorbent layer 12 and on the skin side of the back layer 14. It is an absorbent layer that absorbs bodily fluids such as excrement. The absorbent layer 13 is roughly elliptical in shape and is located in the approximate center of the pad 1 (more precisely, on the posterior side). Details about the absorbent layer 13 will be explained later.

[0081] The back layer 14 is a sheet component located on the non-skin side of the absorbent layer 13. The back layer 14 forms the shape of the pad 1, and when viewed from above, it has approximately the same shape and size as the surface layer 11. As the back layer 14, sheet components such as liquid-permeable sheets and liquid-impermeable sheets can be used, for example, sheet films made of synthetic resin, breathable films, pulp, paper, nonwoven fabrics, breathable liquid-resistant sheets, or sheet components composed of combinations thereof. In this embodiment, a sheet component obtained by mixing rayon, polyethylene terephthalate (PET), and pulp is used.

[0082] The finger insertion piece 15 is a piece member used to form the finger insertion portion 20. The finger insertion portion 20 is the space between the finger insertion piece 15 and the backing layer 14, which is the space for the wearer to insert their fingers when wearing the pad 1. The length of the finger insertion piece 15 in the front-back direction is shorter than that of the backing layer 14, and the length in the width direction is also shorter than that of the backing layer 14. In addition, the finger insertion piece 15 is positioned on the rear side in the front-back direction, closer to the non-skin side than the backing layer 14. The two sides of the finger insertion piece 15 in the width direction are joined and fixed to the non-skin side of the backing layer 14 by finger insertion piece joints 16 formed by an adhesive such as a hot melt adhesive (see reference). Figure 2 The front end and rear end of the finger insertion piece 15 each have openings in the finger insertion piece 15 and the back layer 14 that are not fixed by adhesive. The front opening is larger than the rear opening. The wearer inserts a finger (e.g., the middle finger) through the front opening of the finger insertion part 20, thereby enabling the pad 1 to be placed against the labia while supporting the pad 1.

[0083] As the finger insertion sheet 15, the same material as the surface layer 11 and the back layer 14 can be used. For example, sheet components made from composite synthetic fibers such as PE / PP, PE / PET, and PP / PP, such as spunlace nonwoven fabric, shrinkable nonwoven fabric, stretchable spunbond nonwoven fabric, rayon, cellulose acetate, cotton, pulp, or synthetic resins (e.g., polyethylene terephthalate: PET), breathable membranes, paper, and breathable liquid-resistant sheets can be used. Alternatively, sheets with elasticity such as synthetic rubber, films made from amorphous olefin resins, open-cell foam films, meshes, woven fabrics or fabrics formed by weaving synthetic rubber filaments into woven fabrics, spunbond nonwoven fabrics with synthetic rubber as the main component, meltblown nonwoven fabrics, and foam sheets can also be used. In this embodiment, a sheet component mainly composed of pulp and rayon is used.

[0084] Furthermore, while the pad 1 in this embodiment is designed to be bent towards the non-skin side at the fold line F in an unused state, it is not limited to this. For example, it may not have the fold line F and may not be bent in an unused state, and the wearer may bend the pad towards the non-skin side and wear it. Alternatively, it may have multiple fold lines F. The fold line F may have a crease formed by bending or it may not have a crease.

[0085] <Regarding wearing pad 1>

[0086] The pad 1 is worn by folding its central portion in the width direction towards the non-skin side and then contacting the wearer's skin (excretory opening). In this embodiment, the pad 1 is a menstrual product, folded towards the non-skin side with a protrusion at fold line F. The central portion of the pad 1 in the width direction is inserted between the woman's labia, thus enabling it to be worn. Compared to sanitary napkins, the pad 1 has a higher degree of contact with the body (excretory opening), therefore, leakage of excrement (menstrual blood) is less likely, and discomfort during excretion is less likely.

[0087] When wearing the pad, the wearer inserts their fingers (index or middle finger) into the finger insertion part 20 from the front of the pad 1, which is bent at the fold F, and then presses the pad 1 against and clamps it between the labia. This allows it to be worn. After use, the worn pad 1 can be removed into the toilet bowl, or it can be grasped by hand and placed into the toilet bowl for flushing. For flushing, it is preferable that the components and adhesive of the pad 1 are made of biodegradable, water-dispersible, or water-soluble materials. By flushing it into the toilet, the time and effort required to dispose of the pad 1 as waste can be reduced, or the amount of waste can be reduced.

[0088] Furthermore, "biodegradability" refers to the following: in the presence of bacteria such as actinomycetes and other microorganisms, following natural processes, under anaerobic or aerobic conditions, a substance is decomposed into gases such as carbon dioxide or methane, water, and biomass. It also refers to the following: the biodegradability (biodegradation rate, degree of biodegradation, etc.) of the substance is comparable to naturally occurring materials such as fallen leaves or synthetic polymers recognized as biodegradable under the same conditions. "Water dispersibility," also known as "hydrolysis," refers to the following property: although it has no effect on the limited amount of water (menstrual blood) at the time of wear, it allows the fibers to easily disperse into small fragments in large amounts of water or flowing water, to a degree that is at least not enough to clog typical toilet pipes. "Water solubility" refers to the following property: although it has no effect on the limited amount of water (menstrual blood) at the time of wear, it dissolves in large amounts of water or flowing water.

[0089] <About Absorption Layer 13>

[0090] Figure 5 This is a top view illustrating the structure of the absorbent layer 13. In this embodiment, the absorbent layer 13, starting from the skin side in the thickness direction, sequentially comprises a skin-side sheet 131, an absorbent core 132, and a non-skin-side sheet 133. Furthermore, as... Figure 5 As shown, when pad 1 is divided into three equal parts along the width direction, the area in the center is designated as the central area CR, and the areas on both sides are designated as the end areas SR.

[0091] The absorbent core 132 is a part that absorbs and retains liquids (body fluids) such as menstrual blood, possessing both absorbency and water retention properties. For example, it can be made alone or in combination with continuous foams of pulp, chemical pulp, rayon, cellulose acetate, natural cotton, synthetic fibers, cellulose foam, or synthetic resin. Furthermore, it can be a mixture of granular polymer absorbents, fibrous polymer absorbents, or sheet-like polymer absorbents. Moreover, to maintain the volume of the absorbent core and improve water retention, it can be mixed with chemical pulp, cellulose acetate, or synthetic fibers that are cross-linked and shrunken by a cross-linking agent. In the pad 1, pulp fibers (absorbent fibers) shaped into a specified form are used.

[0092] The skin-side sheet 131 is a component that covers the absorbent core 132 from the skin side, and the non-skin-side sheet 133 is a component 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, rayon, regenerated cellulose such as fibrillated rayon, semi-synthetic cellulose such as cellulose acetate and cellulose triacetate, and materials obtained by hydrophilicating thermoplastic hydrophobic chemical fibers. 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 wet-processed thin cotton paper made from 100% pulp.

[0093] Furthermore, by providing the skin-side panels 131, excrement reaching the absorbent layer 13 can easily diffuse horizontally, allowing the absorbent core 132 to absorb the horizontally diffused excrement. Thus, the absorbent core 132 can quickly absorb excrement, thereby reducing discomfort to the wearer's skin.

[0094] In addition, a plurality of slits 18, 18... and a plurality of compression sections 19, 19... are provided in the absorption layer 13. Figure 5 (Not shown in the figure). The slit 18 is a cut that penetrates at least through the absorbent layer 13 (skin side sheet 131, absorbent core 132, and non-skin side sheet 133) in the thickness direction. However, the slit 18 may also penetrate through the absorbent layer 13 and the sub-absorbent layer 12 in the thickness direction. By providing this slit 18, the absorbent layer 13 and the sub-absorbent layer 12 can easily and softly deform to follow the wearer's body movements when the pad 1 is worn, thus improving fit. In addition, by allowing the absorbed excrement to diffuse along the slit 18 in the front-back and left-right directions, the excrement can be absorbed and retained over a larger area of ​​the absorbent core 132. Furthermore, the slit 18 is formed by making a cut from the non-skin side of the absorbent layer 13 in the thickness direction using a cutter or the like, as detailed later. Therefore, in the pad 1 of this embodiment, a slit (gap) is formed at least in the non-skin side sheet 133.

[0095] The slit 18 has a first slit 18a along the width direction and a second slit 18b along the front-back direction. Here, "slit along the width direction" refers to a slit whose angle (or tangent of the slit) with the width direction is less than 45 degrees. That is, the first slit 18a includes a slit arranged parallel to the width direction and a slit arranged at a predetermined angle of less than 45 degrees relative to the width direction. Similarly, "slit along the front-back direction" refers to a slit whose angle (or tangent of the slit) with the front-back direction is less than 45 degrees. That is, the second slit 18b includes a slit arranged parallel to the front-back direction and a slit arranged at a predetermined angle of less than 45 degrees relative to the front-back direction.

[0096] The compression section 19 is a portion that compresses the absorbent layer 13 (skin side sheet 131, absorbent core 132, and non-skin side sheet 133) and the sub-absorbent layer 12 along the thickness direction. For example, this compression section 19 is formed by overlapping the absorbent layer 13 and the sub-absorbent layer 12 along the thickness direction and performing an embossing process. (Ref.) Figure 4 By providing the compression section 19, the multiple fibers constituting the absorbent layer 13 and the sub-absorbent layer 12 are pressed together, making it easy for the absorbent layer 13 and the sub-absorbent layer 12 to maintain their respective shapes and preventing them from spreading out. Therefore, it is possible to prevent the absorbent layer 13 from deforming or twisting when the wearer moves their body while wearing the pad 1, resulting in poor fit or leakage of excrement.

[0097] Furthermore, the absorbent layer 13 and the sub-absorbent layer 12 are only pressed together by the compression section 19, without the use of adhesives or the like for fixation. Therefore, when the used pad 1 is flushed into the toilet, if the compression section 19 becomes wet with water, the compression bonds (hydrogen bonds) between the fibers break, and the fibers constituting the absorbent layer 13 and the sub-absorbent layer 12 easily disperse. As a result, hydrolysis (water dispersibility) is improved, making it less likely for problems such as clogging toilet pipes to occur.

[0098] Furthermore, in the absorbent core 132 of this embodiment, the pulp fiber (absorbent fiber) includes absorbent fiber made of broadleaf trees, namely broadleaf tree absorbent fiber (broadleaf pulp). This broadleaf tree absorbent fiber has the following characteristics: compared with the absorbent fiber made of coniferous trees (coniferous pulp), the fiber length is shorter and the fiber diameter is finer.

[0099] Figure 6 This is a graph showing the distribution of fiber lengths in hardwood absorbent fibers (hardwood pulp) and softwood absorbent fibers (softwood pulp). The horizontal axis represents fiber length (mm), and the vertical axis represents frequency (%). Figure 6As shown, the average fiber length of coniferous pulp is approximately 2.5 mm, with a relatively wide distribution (including fibers longer than 3 mm; standard deviation is 1.6). In contrast, the average fiber length of absorbent hardwood fibers is approximately 0.79 mm, with a narrower distribution (standard deviation is 0.27).

[0100] Furthermore, the average fiber length of pulp fibers refers to the length-weighted average fiber length L(l) obtained by measuring the centerline fiber length (Cont). For the length-weighted average fiber length, the L(l) value is measured using the Kajaani FiberLab fiber properties (off-line) instrument manufactured by Metso Automation. This is also the method recommended in JIS P 8226-2 (Pulp – Fiber Length Measurement Method Based on Optical Automatic Analysis – Non-polarized Light Method).

[0101] The absorbent core 132 is composed of short-fiber absorbent fibers (average fiber length of approximately 0.8 mm) such as those from hardwood pulp, thus exhibiting high water retention. For example, when comparing absorbents made from short-fiber hardwood pulp and absorbents made from long-fiber softwood pulp at the same weight, the fiber number density of hardwood pulp is greater than that of softwood pulp. That is, by using hardwood pulp, the absorbent core 132 can be made more dense than when using softwood pulp. Furthermore, by making the absorbent core 132 more dense, the capillary effect can be improved, and water retention can be enhanced. In addition, the fiber number density is equivalent to the average number of fibers per unit area, and is a value obtained by estimating the number of fibers per unit area in the case of the densest filling structure using fiber thickness and average inter-fiber distance.

[0102] <Manufacturing Method of Interlabial Pad 1>

[0103] Next, the manufacturing method of the interlabial pad 1 will be explained. Figure 7 This is a flowchart illustrating the manufacturing process of pad 1 in this embodiment. Figure 8 This is a schematic diagram illustrating a manufacturing apparatus 500 for producing absorbent articles such as pad 1. Furthermore, in Figure 7 and Figure 8 The representative processes related to the manufacture of pad 1 are described, but not all of the manufacturing processes are shown.

[0104] Figure 8 The manufacturing apparatus 500 shown is implemented sequentially Figure 7The processes shown (S101~S110) enable the intermittent manufacture of the pad 1 and other absorbent articles of this embodiment. The manufacturing apparatus 500 includes a conveying mechanism 510, an absorbent core stacking mechanism 520, a secondary absorbent layer stacking mechanism 530, a reversing mechanism 540, a first slit forming mechanism 550, a second slit forming mechanism 560, a cutting and sealing mechanism 570, a folding mechanism 580, a finger insert mounting mechanism 590, and an unwinding mechanism 595.

[0105] In the manufacturing process of pad 1, a conveying process (S101) is first performed, in which the continuous body constituting the non-skin side sheet 133 of the absorbent layer 13 is conveyed along the conveying direction. Furthermore, in the manufacturing apparatus 500, the conveying direction is along the front-back direction of pad 1. Hereinafter, the conveying direction will also be referred to as the "MD direction (Machine Direction)," and the direction orthogonal to the conveying direction (the direction along the width direction of pad 1) will also be referred to as... Figure 8 The direction of depth on the paper (in the center) is called the "CD direction (Cross Direction)".

[0106] In the conveying process, after the non-skin side sheet continuous body 133a (substrate sheet) with the non-skin side sheets 133 connected along the MD direction is released from the roll, it is conveyed from the upstream side to the downstream side in the MD direction by a conveying mechanism 510 composed of conveying rollers or the like at a predetermined conveying speed. Furthermore, by performing each step of S102 to S110 during the conveying of the non-skin side sheet continuous body 133a, the pad 1 is manufactured.

[0107] Next, an absorbent core lamination process (S102) is performed, in which an absorbent core 132 is laminated onto a non-skin side sheet continuous 133a (substrate sheet) conveyed along the MD direction using an absorbent core lamination mechanism 520. The absorbent core lamination mechanism 520 includes a fiber unwinding device 521, a material supply unit 522, and a rotating roller 523.

[0108] Figure 9 This is a flowchart illustrating the specific actions (processes) performed in the absorbent core lamination process (S102). In the absorbent core lamination process, a defibering process (S201) is first performed, in which pulp sheets are defibered to produce pulverized pulp, which serves as the raw material for the absorbent core 132. The pulverized pulp is manufactured by pulverizing the pulp sheets PS1 using a defibering device 521. A sawtooth cylinder 521m is provided in the defibering device 521. Furthermore, in this embodiment, as described above, the pulp sheets PS1, which serve as the raw material for forming the absorbent core 132, are primarily composed of pulp containing broadleaf tree pulp, but may also contain softleaf tree pulp or be a mixture of pulp and spunlace.

[0109] Figures 10A-10C This is a diagram illustrating the structure of the 521m sawtooth cylinder. Figure 11 This diagram illustrates the method of defiberizing PS1 pulp sheets using a sawtooth cylinder 521m. The sawtooth cylinder 521m is a cylindrical rotating body capable of rotating around a rotation axis 521Ar. Figure 10A In this configuration, the rotating shaft 521Ar is positioned along the CD direction, and the saw blade cylinder 521m rotates counterclockwise around the rotating shaft 521Ar. Multiple saw blades 525, 525… are arranged on the circumferential surface 521mf of the saw blade cylinder 521m. For example… Figure 9 As shown in B, saw blade 525 is a finer blade along a specified direction (in...). Figure 10B A strip-shaped cutting tool (within the MD direction) is arranged in a spiral wound manner along the circumferential direction of the circumferential surface 521mf within a saw cylinder 521m. In this embodiment, as... Figure 10C As shown, the saw blades 525 are configured to be spaced approximately 5 mm apart along the CD direction of the circumferential surface 521mf.

[0110] For example, in the saw blade 525 of this embodiment, a plurality of blades with a thickness of 0.8 mm and a height of 7 mm are provided at a spacing of approximately 12.7 mm in the MD direction (see reference). Figure 10B The saw blade 525 is installed at approximately 5mm intervals along the CD direction of the circumference 521mf of the saw tooth cylinder 521m (refer to...). Figure 10C Furthermore, with the saw blade 525 installed, the outer diameter of the saw tooth cylinder 521m (including the diameter of the saw tooth cylinder 521m with the cutting tip of the saw blade 525) is approximately 450mm to 500mm. However, the above dimensions are just one example and can be appropriately modified according to the structure, configuration space, and other conditions of the fiber unwinding device 521.

[0111] During defiberization, the saw cylinder 521m is rotated to finely pulverize the pulp sheet PS1 released from the roll by cutting the surface of the pulp sheet PS1 with the saw blade 525, thereby producing pulverized pulp. In this embodiment, a method such as... Figure 11 The feed roller 526, which is configured to face the sawtooth cylinder 521m in the MD direction, performs fiber defibering. The feed roller 526 is, for example, a rotating body that can rotate while the pulp sheet PS1 is supported on the circumferential surface by a clamping mechanism (not shown).

[0112] exist Figure 11In this process, the gap (interval in the MD direction) between the circumferential surface of the feed roller 526 and the tip of the saw blade 525 located in the saw cylinder 521m is adjusted to approximately 0.5 mm, for example. Then, while supporting the pulp sheet PS1, the feed roller 526 is rotated to convey the pulp sheet PS1 to the side of the saw cylinder 521m, and the saw cylinder 521m is rotated at a predetermined speed in the opposite direction to the feed roller 526. Therefore, the pulp sheet PS1 is defiberized at the point where the circumferential surface of the feed roller 526 is closest to the tip of the saw cylinder 521m (saw blade 525) to produce pulverized pulp.

[0113] Using the saw cylinder 521m of this embodiment, the amount of pulp sheet PS1 pulverized per unit width per unit time is 7.5~60 kg / hr, preferably 9.0~55 kg / hr. For example, if the maximum pulverization amount per unit time is set to 60 kg / hr, the diameter d of the saw cylinder 521m including the blade tip of the saw blade 525 is set to 470 mm, the rotation speed is set to 2000 rpm, and the feed rate of the pulp sheet P1 (width 525 mm in the CD direction) in the MD direction is set to 2.66 m / min, when the saw cylinder 521m rotates once (=3.14d), and the distance (lead) of the spirally wound saw blade 525 advancing axially is 20 mm, each blade of the saw blade 525 cuts the pulp sheet P1 in the MD direction (feeding direction of the pulp sheet P1) by 0.0114 mm in one cut. By finely crushing the pulp sheet P1 in this way, it is possible to produce appropriately sized crushed pulp that does not contain the fiber clumps (NOTS) described later.

[0114] Next, return to Figure 9 The absorbent core forming process (S202) involves using pulverized pulp as material to form the absorbent core 132, and the transfer process (S203) involves transferring the formed absorbent core 132 onto a substrate sheet (in this case, a non-skin-side continuous sheet 133a) being transported along the MD direction. In this embodiment, the absorbent core forming process (S202) and the transfer process (S203) are performed using a rotating roller 523.

[0115] The pulp pulverized by the saw-tooth cylinder 521m is collected inside the material supply section 522 located below the defiberization device 521 and supplied to the rotating drum 523. The material supply section 522 is configured to cover the upper part of the rotating drum 523, mix thermoplastic resin in the pulverized pulp, and further mix superabsorbent polymer particles (SAP) if necessary, and supply these mixtures to the rotating drum 523 by air conveying.

[0116] The rotating drum 523 is a hollow cylindrical drum and has a suction mechanism (not shown) that draws air inward from the outer side of its outer circumference. Additionally, a plurality of recesses 523r are formed at predetermined intervals in a mold for filling the absorbent core 132 with material on its outer circumference. When the rotating drum 523 rotates and the recesses 523r enter the material supply section 522, the material (pulp) supplied from the material supply section 522 to the absorbent core 132 is drawn into the recesses 523r by the suction mechanism. Thus, the absorbent core 132 is formed (S202).

[0117] Then, as the rotating roller 523 rotates and the recess 523r containing the material of the absorbent core 132 reaches the bottom of the roller, the material of the absorbent core 132 detaches from the recess 523r and is transferred onto the conveyed substrate sheet (non-skin side sheet continuous 133a) (S203), and is handed over to the next process. Thus, the absorbent core 132 is laminated on the skin side of the non-skin side sheet 133 (S103).

[0118] Next, return to Figure 7 The substrate sheet with the absorbent core 132 is conveyed from the absorbent core stacking mechanism 520 to the downstream side in the conveying direction (MD direction) and overlaps with the continuum 131a of the skin side sheet 131 (see reference). Figure 8 And, in the state where the absorption layer 13 is formed, it reaches the sub-absorption layer stacking mechanism 530. Furthermore, for the sake of simplicity, in Figure 8 The following procedures do not include illustrations of the skin side sheet 131.

[0119] Next, a sub-absorbent layer lamination process (S103) is performed, in which the sub-absorbent layer 12 is laminated onto the skin side of the absorbent layer 13 in the thickness direction using a sub-absorbent layer lamination mechanism 530. The sub-absorbent layer lamination mechanism 530 includes a desiccant 531. Similar to the sawtooth cylinder 521m described in FIG10, the desiccant 531 includes a sawtooth cylinder 531m, which is a rotating body with a thin saw blade spirally wound around the circumference of a cylindrical roller. Furthermore, substantially similar to the desiccant 521, the pulp sheet PS2 is pulverized by rotating in a manner that cuts the pulp sheet PS2 discharged from the roll, thereby producing pulverized pulp as the raw material for the sub-absorbent layer 12. The pulverized pulp is directly spread on the substrate sheet, and the layer of pulverized pulp (sub-absorbent layer 12) is laminated onto the skin side of the absorbent layer 13.

[0120] The pulp sheet PS2 used in the sub-absorbent layer lamination process is composed of softwood pulp, and may also contain hardwood pulp or a blend of rayon. Furthermore, the hardwood pulp content in pulp sheet PS2 is lower than that in pulp sheet PS1. As a result, the average fiber length of the sub-absorbent layer 12 is longer than that of the absorbent core 132, and the average fiber diameter is coarser.

[0121] Furthermore, after the sub-absorbent layer 12 is laminated onto the absorbent layer 13, an embossing process is performed to form the compression portion 19. As a result, the multiple fibers constituting the absorbent layer 13 and the sub-absorbent layer 12 are pressed together, and they will not easily peel off or deform when both are laminated.

[0122] Next, a reversal process (S104) is performed using the reversal mechanism 540 to reverse the substrate sheet (absorbing layer 13 and sub-absorbing layer 12) in the thickness direction. Figure 8 In this process, the substrate sheet is conveyed from the left side of the paper to the right side, reversing the conveying direction from right to left, and the thickness direction is also reversed. Therefore, after the reversal process, the substrate sheet is conveyed along the MD direction with the absorbent layer 13 stacked on top of the sub-absorbent layer 12 in the vertical direction.

[0123] Next, a first slit forming process (S105) is performed using the first slit forming mechanism 550 to form a first slit 18a on the absorbent layer 13. The first slit forming mechanism 550 includes a cutting roller 551 and an anvil roller 552. The cutting roller 551 is a rotating body with multiple blades arranged on its circumferential surface in a cylindrical roller and driven to rotate about a rotation axis along the CD direction. The anvil roller 552 is located in the thickness direction (in... Figure 8 A rotating body (in the vertical direction) is arranged facing the cutting roller 551 and driven to rotate around a rotation axis along the CD direction. In this embodiment, as... Figure 8 As shown, a cutting roller 551 is provided on the upper side (non-skin side of the pad 1) in the vertical direction of the manufacturing apparatus 500, and an anvil roller 552 is provided on the lower side (skin side of the pad 1). Furthermore, by using the cutting roller 551 and the anvil roller 552 to clamp and press the substrate sheet (absorbent layer 13 and sub-absorbent layer 12) along the thickness direction, the first slit 18a is formed.

[0124] Figures 12A-12C This is a diagram illustrating the structure of the cutting roller 551 used in forming the first slit 18a. Figure 12A This is a top view of the cutting roller 551 viewed from the MD direction. Figure 12B It is a diagram showing the configuration pattern of multiple blades 551c arranged on the circumferential surface 551f of the cutting roller 551. Figure 12C It means Figure 12B A sectional view of the DD direction. Additionally... Figures 13A-13BThis is a diagram illustrating the structure of the anvil roller 552 used in forming the first slit 18a. Figure 13A This is a top view of the anvil roller 552 viewed from the MD direction. Figure 13B It is an enlarged representation Figure 13A The graph of region E.

[0125] like Figure 12A As shown, the cutting roller 551 of the first slit forming mechanism 550 is a cylindrical rotating body that rotates around a rotation axis Ar1 along the CD direction, and has multiple blades 551c, 551c... protruding outward in the radial direction from the circumferential surface 551f of the cylinder. The multiple blades 551c... Figure 12B The pattern configuration shown, Figure 12B Patterns such as Figure 12A The cutting roller 551 is arranged intermittently along its circumferential surface 551f at predetermined intervals. Multiple blades 551c are each configured to form slits primarily along the CD direction (the width direction of the pad 1). That is, each blade 551c of the cutting roller 551 is arranged primarily parallel to the CD direction or inclined at a predetermined angle of less than 45 degrees relative to the CD direction. Multiple first slits 18a can be formed on the pad 1 using such blades 551c. However, a portion of the slits 18 along the MD direction can also be formed using the cutting roller 551.

[0126] like Figure 13A As shown, the anvil roller 552 of the first slit forming mechanism 550 is a cylindrical rotating body that rotates around the rotation axis Ar2 along the CD direction, and is arranged to face the cutting roller 551 through the pad 1 (substrate sheet) (see reference). Figure 8 Furthermore, while rotating the anvil roller 552 and the cutting roller 551, a slit (cut) corresponding to the shape of the blade 551c is formed on the substrate sheet sandwiched between the two (in this embodiment, the absorption layer 13, the sub-absorption layer 12, etc.).

[0127] Furthermore, a groove 552d that is recessed inward in the radial direction is provided on a portion of the circumferential surface 552f of the anvil roller 552. In this embodiment, a pair of grooves 552d are provided on both sides of the central position CDL of the anvil roller 552 in the CD direction. In addition, the grooves 552d are provided continuously along the circumferential direction of the anvil roller 552 (the direction corresponding to the MD direction).

[0128] Figure 14 This diagram illustrates the operation of forming the first slit 18a using the cutting roller 551 and the anvil roller 552. Figure 14The diagram shows the positional relationship between the blade 551c of the cutting roller 551 and the groove 552d of the anvil roller 552 when the cutting roller 551 and the anvil roller 552 are aligned at their central positions CDL in the CD direction and facing each other.

[0129] like Figure 14 As shown, in the CD direction, there are portions on both sides of the central position of CDCL where the blade 551c overlaps with the groove 552d. For example, in Figure 14 In region F, the first portion np of the blade 551c of the cutting roller 551, located at its center in the CD direction, overlaps with the groove 552d of the anvil roller 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. That is, when the front end of the blade 551c of the cutting roller 551 abuts against the circumferential surface 552f of the anvil roller 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.

[0130] In this case, the second portion cp at both ends of the blade 551c in the CD direction presses against the substrate sheet (absorbent layer 13, etc.) towards the circumferential surface 552f of the anvil roller 552, thereby forming a slit 18. On the other hand, since the first portion np at the center of the blade 551c in the CD direction presses against the groove 552d of the anvil roller 552, the slit 18 is not formed. Thus, in the first slit 18a along the width direction, a slit 18 is formed such that the central portion in the CD direction (width direction) is divided (see reference). Figure 5 The end region SR).

[0131] Furthermore, in the anvil roller 552, it is preferable to chamfer the boundary between the circumferential surface 552f and the groove 552d. Figure 13B In the section, at the boundary between the circumferential surface 552f of the anvil roller 552 and the groove 552d, the corner portion ch, indicated by black ink, is chamfered. By providing such a chamfered portion ch, the force applied when the blade 551c of the cutting roller 551 presses down on the boundary between the portion overlapping with the circumferential surface 552f of the anvil roller 552 in the CD direction (forming the second portion cp of the slit 18) and the portion overlapping with the groove 552d (not forming the first portion np of the slit 18) changes smoothly. Therefore, compared to the case without the chamfered portion ch, 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 circumferential surface 552f and the groove 552d can be as follows: Figure 13B It can be formed in a straight line or in a curve. That is, the boundary between the circumferential surface 552f and the groove 552d can also be a curved shape.

[0132] Next, a second slit forming process (S106) is performed using the second slit forming mechanism 560 to form a second slit 18b on the absorption layer 13. The second slit forming mechanism 560 includes a cutting roller 561 and an anvil roller 562. The cutting roller 561 is a rotating body with multiple blades arranged on its circumferential surface in a cylindrical roller and driven to rotate about a rotation axis along the CD direction. The anvil roller 562 is located in the thickness direction (in... Figure 8 A rotating body is arranged facing the cutting roller 561 in the vertical direction and driven to rotate around a rotation axis along the CD direction. Furthermore, in the second slit forming process, the second slit forming mechanism 560 cuts the substrate sheet (absorbent layer 13 and sub-absorbent layer 12) into... Figure 1 It has a roughly elliptical shape, as shown by the dashed line.

[0133] Figures 15A-15C This is a diagram illustrating the structure of the cutting roller 561 used in forming the second slit 18b. Figure 15A This is a top view of the cutting roller 561 viewed from the MD direction. Figure 15B It is a diagram showing the configuration pattern of multiple blades 561c arranged on the circumferential surface 561f of the cutting roller 561. Figure 15C It means Figure 15B A cross-sectional view of GG.

[0134] like Figure 15A As shown, the cutting roller 561 of the second slit forming mechanism 560 is a cylindrical rotating body that rotates around a rotation axis Ar3 along the CD direction, and has multiple blades 561c, 561c... protruding outward in the radial direction from the circumferential surface 561f of the cylinder. The multiple blades 561c... Figure 15B The pattern configuration shown, Figure 15B Patterns such as Figure 15A The cutting roller 561 is arranged intermittently at predetermined intervals along its circumferential surface 561f. Multiple blades 561c are configured to form slits primarily along the MD direction (the front-to-back direction of the pad 1). That is, the blades 561c of the cutting roller 561 are arranged primarily parallel to the MD direction or inclined at a predetermined angle of less than 45 degrees relative to the MD direction. Multiple second slits 18b can be formed on the pad 1 using such blades 561c. However, a portion of the slit 18 along the CD direction can also be formed using the cutting roller 561.

[0135] Additionally, a circumferential blade 561rc is provided on the circumferential surface 561f of the cutting roller 561 in a manner that surrounds a plurality of blades 561c, 561c... along the MD direction. The shape of the circumferential blade 561rc and the outer edge of the sub-absorbent layer 12 ( Figure 1The sheet-like sub-absorbent layer 12, which is stacked in the sub-absorbent layer stacking process (S103) as shown by the dotted line, is set to match the sub-absorbent layer 12. The sub-absorbent layer 12 is then cut in a manner similar to a so-called mold release, thereby forming the sub-absorbent layer 12 into a roughly elliptical shape.

[0136] The anvil roller 562 of the second slit forming mechanism 560 is a cylindrical rotating body that rotates around a rotation axis along the CD direction, and is positioned facing the cutting roller 561 across the pad 1 (substrate sheet) (see reference). Figure 8 Furthermore, no recess (groove) corresponding to the groove 552d of the anvil roller 552 (see Figure 13) is provided on the circumferential surface of the anvil roller 562. While rotating the anvil roller 562 and the cutting roller 561, a slit (cut) corresponding to the shape of the blade 561c is formed on the portion of the circumferential surface of the anvil roller 562 that abuts against the front end of the blade 561c of the cutting roller 561. This slit is sandwiched between the two substrate sheets (in this embodiment, the absorption layer 13, the sub-absorption layer 12, etc.). Simultaneously, at the portion of the circumferential surface of the anvil roller 562 that abuts against the front end of the circumferential blade 561rc of the cutting roller 561, the substrate sheet (absorption layer 13 and sub-absorption layer 12) sandwiched between the two is cut into an approximately elliptical shape along the shape of the circumferential blade 561rc.

[0137] Furthermore, a portion of the blade 561c of the cutting roller 561 of the second slit forming mechanism 560 is arranged in the CD direction at a position overlapping with the groove 552d of the anvil roller 552 of the first slit forming mechanism 550 (see reference). Figure 15B Therefore, a portion of the second slit 18b formed in the second slit forming process (S106) will be formed in the portion of the first slit 18a that was not formed in the first slit forming process (S105) (the portion corresponding to the groove 552d of the anvil roller 552).

[0138] After forming slits 18 on the absorber layer 13 (and sub-absorber layer 12) through the first slit forming process (S105) and the second slit forming process (S106), a continuous body 11a of the surface layer 11 is laminated from the skin side of the sub-absorber layer 12 in the thickness direction, and a continuous body 14a of the back layer 14 is laminated from the non-skin side of the absorber layer 13.

[0139] Next, a cutting and sealing process (S107) is performed. In this process, a cutting and sealing mechanism 570 is used to cut the continuous body 11a of the surface layer 11 and the continuous body 14a of the back layer 14, which are sandwiched together along the thickness direction with the absorbent layer 13 and the sub-absorbent layer 12, into a predetermined shape and then join (seal) them together. In this cutting and sealing process, in the region outside of the sub-absorbent layer 12 (absorbent layer 13), a known welding method such as heat fusion or ultrasonic welding, or an adhesive such as a hot melt adhesive, is used to join the continuous body 11a of the surface layer 11 to the continuous body 14a of the back layer 14. That is, in Figure 1 In the planar state of the pad 1 shown, the area outside the portion surrounded by the dashed line representing the sub-absorbent layer 12 seals the surface layer 11 and the back layer 14 together. Then, the individual pads 1 are cut out by cutting the strip-shaped continuous 11a, 14a extending in the MD direction along the outer edge (outline) of the pad 1.

[0140] Next, the folding mechanism 580 is used to perform a folding process (S108) in which each pad 1 is bent at the center of its width direction (CD direction) along the front-to-back direction (MD direction). Figure 3B As shown, the folding mechanism 580 folds the pad 1 into a triangular shape that bulges toward the skin at the fold line F along the front-to-back direction (MD direction).

[0141] Next, a finger insert installation step (S109) is performed, in which the finger insert 15 is installed on the non-skin side of the back layer 14 using the finger insert installation mechanism 590. Figure 3B As shown, the finger insert mounting mechanism 590 mounts the finger insert 15 onto the non-skin side of the back layer 14 of the pad 1, which is bent into a triangular shape.

[0142] Next, the unloading mechanism 595 is used to perform the unloading process (S110) to unload the pad 1 (absorbent material). Figure 16 This diagram illustrates the structure and operation of the unwinding mechanism 595. The unwinding mechanism 595 has multiple rollers 595a~595e and two belts 595B1 and 595B2 that convey the pad 1 along the MD direction while it is clamped in place. Figure 16In the process, five rollers, namely the first roller 595a, the second roller 595b, the third roller 595c, the fourth roller 595d, and the fifth roller 595e, are arranged from the upstream side to the downstream side in the MD direction. Furthermore, belts 595B1 and 595B2 are wound around each roller. By passing the pad 1 between these rollers 595a to 595e along the conveying direction and bending it along the circumference of the rollers on one side and the other side in the thickness direction, the distribution and interlacing deviations of the pulp fibers constituting the absorbent layer 13 are untied and homogenized. Moreover, the number and structure of the rollers provided in the untiing mechanism 595 are not limited to those shown in FIG. 15 and can be appropriately modified according to the product specifications of the pad 1 and the structure of the manufacturing apparatus 500.

[0143] In the unwinding mechanism 595, two rollers arranged adjacent to each other along the MD direction are respectively positioned at locations offset in the vertical direction. More specifically, as... Figure 16 In this way, each roller is positioned so that the portion of the first roller 595a that abuts against the pad 1 is located at the outermost side in the vertical direction (in... Figure 16 The position of point P on the lower side of the first roller 595a is located at the other side in the vertical direction of the portion of the circumference of the second roller 595b that abuts against the pad 1. Figure 16 The position of point Q on the upper side of the second roller 595b is on the lower side (the side closest to the top and bottom).

[0144] According to this structure, the pad 1, conveyed along the MD direction, bends towards one side and the other side in the thickness direction by winding around the circumference of the rollers as it passes through each roller. For example, in Figure 16 In this process, when the pad 1 is wound around the circumference of the first roller 595a, it bends considerably in a downward convex direction (one side in the thickness direction), and when the pad 1 is wound around the circumference of the second roller 595b, it bends considerably in a upward convex direction (the other side in the thickness direction). As a result, the absorbent layer 13 and the sub-absorbent layer 12 can be easily and flexibly deformed, improving the fit when wearing the pad 1. Furthermore, since the deviation of the pulp fibers is corrected, liquid absorbency and liquid diffusion can be improved, and by bending the absorbent layer 13 and the like in the thickness direction, the slit 18 provided in the absorbent layer 13 can be easily opened.

[0145] In addition, the disassembly mechanism 595 can also be modified as follows. Figure 17 This diagram illustrates a variation of the disassembly mechanism 595. In Figure 17 In the disassembly mechanism 595 shown, with Figure 16 Compared to the previous case, the vertical spacing between adjacent rollers 595a~595e along the MD direction narrows, and pad 1 is conveyed by being sandwiched between adjacent rollers. Figure 17In this process, by being sandwiched between the lower circumferential surface of the first roller 595a and the upper circumferential surface of the second roller 595b, the pad 1 is bent to one side and the other side in the thickness direction. Furthermore, by satisfying the positional relationship of points P and Q mentioned above, the pad 1 can be efficiently unpacked.

[0146] After the unpacking process, pad 1 is individually packaged on the downstream side in the MD direction and shipped to the market as an interlabial pad package, either individually or in multiple packages.

[0147] <Regarding the pulp constituting absorbent core 132>

[0148] As described above, the absorbent core 132 of the pad 1 is formed from pulverized pulp obtained by defibering pulp sheets PS1 containing hardwood pulp in the defibering process (S201). That is, the shape and size of the pulp fibers constituting the absorbent core 132 are greatly affected by the degree of defibering of the pulp sheets PS1 in the defibering process. Furthermore, in this embodiment, by using the sawtooth cylinder 521m shown in FIG10 for defibering, it is possible to manufacture an absorbent core 132 (pulp fibers) with good hydrolytic properties and shape stability.

[0149] The absorbent core 132 of this embodiment is formed with a length of 50-120 mm in the front-to-back direction and an average weight per unit area of ​​50-120 gsm. Therefore, when wearing the pad 1, it can reliably conform to the wearer's vaginal opening, and achieves good skin feel and liquid absorbency. Furthermore, the absorbent core 132 of this embodiment comprises various types of pulverized pulp (pulp fibers) with different lengths and shapes.

[0150] Previously, pulverized pulp (pulp fibers) that form absorbent cores could be classified into three forms produced during the defiberization process. These were: longer pulp fibers that aggregated into tufts of fibers (hereinafter also called "NOTS"), fibers short enough not to interweave with other fibers (hereinafter also called "FINE"), and fibers longer than FINE but shorter than NOT (hereinafter also called "ACCEPT").

[0151] In an absorbent core, if the content of NOTs (clumped fibers) among these three types of fibers is high, the skin feel may be worse when worn, and it may be difficult to disintegrate into water after use. Furthermore, if the content of fine fibers is high, the interweaving of the fibers weakens, making it difficult for the absorbent core to maintain its shape stably, or the fibers may unravel during use, resulting in poor water retention. Therefore, to improve the shape stability, water retention, and hydrolysis resistance of the absorbent core, it is preferable to maximize the content of ACCEPT (qualified fibers) among the fibers constituting the absorbent core.

[0152] However, for the absorbent cores that have been used in absorbent articles in the past, the content of NOTs (clumped fibers) and FINE (fine fibers) will increase during the defiberization process of pulp sheets, making it difficult to achieve both good hydrolysis and shape stability.

[0153] In contrast, the absorbent core 132 manufactured using the manufacturing apparatus 500 of this embodiment has a lower content of NOTS (clumped fibers) and FINE (fine fibers) than in the past. Figure 18 is a graph showing data comparing the content ratios of NOTS (clumped fibers), FINE (fine fibers), and ACCEPT (qualified fibers) in the absorbent core 132 formed by the manufacturing apparatus 500 of this embodiment and the absorbent core formed by conventional manufacturing methods. Figure 19 This is a diagram illustrating the method for determining the proportions of NOTS (clumped fibers), FINE (fine fibers), and ACCEPT (qualified fibers) contained in absorbent core (pulverized pulp).

[0154] The proportions of NOTS (bulk fibers), FINE (fine fibers), and ACCEPT (qualified fibers) in the pulverized pulp were determined by conducting an evaluation test on the pulverized pulp according to the "Sieve Test Method for Chemical Products" specified in JIS K 0069-1992. The evaluation test in this embodiment uses... Figure 19The test is performed using a pulping evaluation tester 300 as shown (e.g., Nisshin Machinery Manufacturing Co., Ltd.: Pulp Pulping Evaluation Tester). The pulping evaluation tester 300 includes first sieves 311 to fifth sieves 315 and a vibration device 320. The first sieves 311 to fifth sieves 315 are metal meshes (e.g., metal meshes as specified in JIS Z 8801) with different mesh sizes (25.4 mm spacing). In the pulping evaluation tester 300, various mesh sizes are arranged sequentially from the top in the vertical direction: 42 mesh for the first sieve, 4.7 mesh for the second sieve, 7.5 mesh for the third sieve, 14 mesh for the fourth sieve, and 60 mesh for the fifth sieve. The vibration device 320 is a device that provides vibration to the sieves 311 to 315.

[0155] Evaluation tests were conducted on the pulping of the absorbent core 132 manufactured by the manufacturing apparatus 500 of this embodiment and the absorbent cores 1-3 manufactured by conventional manufacturing methods as comparative examples. In Comparative Examples 1-3, a conventional mill saw was used as the defiberizing device to defiberize the pulp. In Comparative Example 1, defiberization was performed at the same amount of pulping (kg / hm) as in this embodiment. In Comparative Example 2, defiberization was performed at twice the amount of pulping as in Comparative Example 1, and in Comparative Example 3, defiberization was performed at three times the amount of pulping as in Comparative Example 1.

[0156] In the evaluation test of pulverized pulp, firstly, the vibration device 320 was set (intensity setting dial: 70, time setting: 55 minutes, vibration: continuous). Then, the pulverized pulp to be evaluated was unpacked and placed into the second sieve 312. The pulverized pulp to be evaluated was approximately 5 mg, and its accurate weight was measured beforehand. Next, the first sieve 311 was placed on top and fixed using the clamping unit, and the vibration device 320 was activated. After 5 minutes of operation, the clamping unit was released, and the first sieve 311 was removed.

[0157] At this point, the pulp remaining on the second sieve 312 to the fourth sieve 314 is designated as NOTS (clumped fibers). That is, fibers that did not pass through a sieve of 14 mesh or larger are designated as NOTS (clumped fibers) and their weight is measured. Additionally, the pulp that did not remain on any sieves 312 to 315 is designated as FINE (fine fibers). That is, fibers that passed through a sieve of 60 mesh are designated as FINE (fine fibers) and their weight is measured. Furthermore, the remaining pulp is designated as ACCEPT (acceptable fibers). That is, fibers that passed through the second sieve 312 to the fourth sieve 314 but did not pass through the fifth sieve 315 are designated as ACCEPT (acceptable fibers). This test is repeated multiple times (e.g., more than twice), and the average weight of NOTS (clumped fibers), FINE (fine fibers), and FINE (fine fibers) is calculated for each. Then, the content ratio of each fiber is determined based on the ratio of its weight to the total weight (5 mg) of the pulp being evaluated.

[0158] The results of the pulp evaluation test showed that Comparative Examples 1-3 all contained more than 14% NOTS (clumped fibers). Furthermore, the more fiber was unwound per unit time, the higher the NOTS content became. Additionally, Comparative Examples 1-3 contained 11% to 12% FINE (fine fibers) (see Figure 18). In contrast, it was determined that the pulp constituting the absorbent core 132 of this embodiment did not contain NOTS (clumped fibers). Furthermore, the FINE content was 19%, and the ACCEPT (acceptable fibers) content was 81% (see Figure 18).

[0159] In the absorbent core 132 of this embodiment, since the proportion of NOTs (clumped fibers) is relatively small, larger fiber clumps are prevented from remaining in the water without disintegrating. When flushed down the toilet, the fibers constituting the absorbent core 132 tend to disperse more finely. The weight of NOTs (clumped fibers) relative to the total weight is at least 10% or less; compared to cases where the weight of NOTs (clumped fibers) is greater than 10%, hydrolysis is higher. Furthermore, in the absorbent core 132 of this embodiment, the proportion of FINE (fine fibers) is less than 20% of the total weight, and more than 80% of the pulp fibers (pulverized pulp) constituting the absorbent core 132 tend to intertwine. That is, the weight of FINE (fine fibers) relative to the total weight is less than 20%; compared to cases where the weight proportion is greater than 20%, the pulp fibers tend to entangle easily, and the shape of the absorbent core 132 is more easily and stably maintained. Therefore, it is possible to manufacture an absorbent core 132 that is shape-stable when worn (in use) but is highly hydrolyzable and easily disintegrates when thrown into the toilet or other similar containers after use.

[0160] Furthermore, in the defiberization process (S201) of this embodiment, the pulp sheet P1 is defibered at a defiberization amount of 7.5 to 60 kg / mh per unit width. When using broadleaf pulp with shorter fiber lengths, the absorbent core may sometimes become compacted and difficult to transfer to the substrate sheet when the pulverized pulp is piled (aggregated) into the recess 523r of the rotating drum 523. However, under the aforementioned conditions, it is easy to transfer to the substrate sheet (the continuous body 133a of the non-skin side sheet) while maintaining the shape of the absorbent core 132. In addition, if the defiberization amount per unit time is increased in the defiberization process (by increasing the rotation speed of the saw cylinder 521m), the proportion of NOTS (clumped fibers) may increase. Conversely, if the defiberization amount per unit time is decreased (by decreasing the rotation speed of the saw cylinder 521m), the proportion of FINE (fine fibers) may increase. Therefore, it is preferable to manufacture the absorbent core 132 within the aforementioned defiberization amount range.

[0161] Furthermore, in the defiberization process (S201) of this embodiment, a saw-tooth cylinder 521m with a saw blade 525 wound around the circumference of a rotating roller is used to defiber the pulp sheet P1 containing broadleaf pulp. By using the saw blade 525 with multiple finer blades to pulverize the pulp sheet P1, it is easier to form finer pulverized pulp compared to defiberization using conventional saw mills or hammer mills. In particular, since the proportion of NOTs (clumped fibers) can be reduced and the proportion of ACCEPT (qualified fibers) of appropriate size can be increased, it is suitable for manufacturing an absorbent core 132 with high hydrolytic properties.

[0162] Furthermore, the absorbent core 132 of this embodiment does not contain NOTES (clumped fibers). As mentioned above, if NOTES (clumped fibers) are included, hydrolysis properties tend to be poor, and the absorbent core 132 may be difficult to decompose when flushed into the toilet. In addition, if NOTES (clumped fibers) are included, there will be areas with locally higher fiber density, making it difficult to achieve uniform water absorption and retention, which may lead to leakage. In contrast, since the absorbent core 132 of this embodiment does not contain NOTES (clumped fibers), an absorbent core 132 with good water absorption, water retention, and hydrolysis properties can be achieved.

[0163] Furthermore, from the viewpoint of the hydrolytic properties of the absorbent core 132, it is desirable that when the pad 1 is flushed down the toilet after use, the multiple pulp fibers (pulverized pulp) constituting the absorbent core 132 can easily come into contact with water and easily disperse from their intertwined state. In the manufacturing method of this embodiment, multiple slits 18 are formed on the absorbent core 132 (absorbent layer 13) through a slit-forming process (S105, S106). As a result, when the pad 1 is flushed down the toilet, water is easily introduced into the interior of the absorbent core 132 through the slits 18, and the pulp fibers easily come into contact with water. In addition, by unraveling the pulp fibers using a disassembly process (S110), water can easily and uniformly penetrate throughout the entire absorbent core 132. Therefore, it is possible to manufacture an absorbent core 132 with good hydrolytic properties.

[0164] Furthermore, an opening process (S110) is performed after the slit-forming process (S105, S106). By performing this process in sequence, the multiple slits 18, 18... formed in the absorbent core 132 during the slit-forming process are easily expanded during the opening process (the slits become easier to open). As a result, when the pad 1 is flushed into the toilet, water can more easily seep in through the slits 18 (slits) and reach the inside of the absorbent core 132. Therefore, the pulp fibers constituting the absorbent core 132 can easily come into contact with water, further improving hydrolysis properties.

[0165] Furthermore, during the unwinding process, the pad 1 is conveyed while being bent, by being wound around the circumference of multiple rollers provided in the unwinding mechanism 595. For example, in Figure 16 In the process, pad 1, supported between belts 595B1 and 595B2, is first wound around the lower circumferential surface of a first roller 595a rotating about a rotation axis along the CD direction, and is bent considerably in a downward convex manner. Then, it is conveyed to a second roller 595b and wound around the upper circumferential surface of the second roller 595b, thereby bending considerably in an upward convex manner. That is, in the vertical direction, the lowest position of the portion where the circumferential surface of the first roller 595a abuts against pad 1 ( Figure 16 Point P) is the highest point of the portion of the second roller 595b that abuts against the pad 1. Figure 16 The point Q is low, which causes the pad 1 to bend more vertically (in the thickness direction) along the circumference of these rollers.

[0166] As in Figure 5As explained, each absorbent core 132 is provided with multiple first slits 18a along the width direction (CD direction) and second slits 18b along the front-to-back direction (MD direction). Furthermore, by conveying the pad 1 (absorbent core 132) along the MD direction while bending it in the thickness direction during the unwinding process, the first slits 18a along the CD direction (width direction) expand or contract along the circumferential surface of the roller (corresponding to the MD direction). Additionally, the second slits 18b along the MD direction (front-to-back direction) expand or contract based on the thickness of the absorbent core 132 and the difference in circumferential speed between the inner and outer circumferential surfaces when passing through the roller circumferential surface. Thus, the multiple slits 18, 18... are easily opened, and when the used pad 1 is thrown into the toilet, etc., water is introduced through the opened slits 18, thereby further improving the hydrolytic properties of the absorbent core 132.

[0167] Furthermore, during the unpacking process, pad 1 is conveyed with its front-to-back direction aligned with the MD direction. For example... Figure 1 , Figure 5 As shown, the pad 1 is formed into an approximately elliptical shape, longer in the front-to-back direction than in the width direction, to conform to the wearer's crotch. That is, the pad 1 is conveyed with its length increasing in the MD direction. Therefore, the pad 1 can bend considerably among the multiple rollers 595a-595e provided in the unwinding mechanism 595. For example, in Figure 16 In this embodiment, by winding the pad 1 around a larger area of ​​the upper half of the circumferential surface of the second roller 595b, it is bent to a state close to 180 degrees. Conversely, if the length of the pad 1 in the MD direction is shorter, the degree of bending is smaller because the area of ​​the pad 1 wound around the second roller 595b in the circumferential direction is narrower. Thus, in this embodiment, by conveying the pad 1 with the front-to-back direction along the MD direction while increasing its length in the MD direction, the pad 1 (absorbent core 132) can be bent efficiently during the unwinding process.

[0168] At this point, it is preferable that the length L13 of the absorbent core 132 in the front-to-back direction (MD direction) is 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 bend the absorbent core 132 (pad 1) during the unwinding process, it is desirable that the absorbent core 132 be wound around the roller in the circumferential direction over the largest possible range. Here, since the circumferential length 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-to-back direction (MD direction) is 1.57 times the diameter of the roller, then theoretically the absorbent core 132 would be wound around the roller in the circumferential direction over a range of 1 / 2. Therefore, by making the length L13 of the absorbent core 132 in the front-to-back direction (MD direction) longer than twice the diameter of the roller, even considering errors such as those when conveying using belts 595B1 and 595B2, it is easy to achieve the desired result. Figure 16 This allows the pad 1 to be reliably wound around the circumference of the roller. Consequently, the pad 1 can be bent more easily, making it easier to open the slit 18. Therefore, hydrolytic properties can be further improved.

[0169] Furthermore, an unwinding process (S110) is performed after the folding-back process (S108). In the folding-back process, the absorbent core 132 (pad 1) is folded and bent at its center in the width direction (CD direction) using a bending line along the front-to-back direction (MD direction). That is, the area on one side and the area on the other side of the center in the width direction (CD direction) of the absorbent core 132 are folded in the thickness direction, and conveyed along the MD direction while the thickness increases. Then, downstream in the MD direction, when the absorbent core 132 bends along the circumferential surface of the rollers 595a~595d of the unwinding mechanism 595, the greater the thickness, the longer the distance from the rotation center of the roller in the radial direction, and the easier it is to pull along the circumferential direction (MD direction) of the roller. For example, in Figure 16 In the pad 1 along the circumferential surface of the second roller 595b, the point R, which is farther from the circumferential surface, is more easily pulled strongly in the circumferential direction than the point Q that abuts against the circumferential surface. In this case, the slit 18 located near the point R is easier to open than the slit 18 located near the point Q in the thickness direction. Therefore, by using the unwinding process to unwind the absorbent core 132, which has become thicker during the folding process, the slit 18 is made easier to open, thereby further improving hydrolytic properties.

[0170] Furthermore, preferably, the total length of the plurality of first slits 18a, 18a... provided in the absorbent core 132 is longer than the total length of the plurality of second slits 18b, 18b... This is explained by the following: by bending the absorbent core 132, which is conveyed along the MD direction during the unwinding process, in the thickness direction, the slits 18 are easier to open. However, in this case, the first slits 18a along the CD direction are easier to open more easily than the second slits 18b along the MD direction. Therefore, if the total length of the first slits 18a is longer than the total length of the second slits 18b, then, as a whole, the length of the slits 18 that are easier to open increases. That is, more slits 18 can be opened efficiently. This improves the hydrolytic properties of the absorbent core 132.

[0171] ===Other Implementation Methods===

[0172] The embodiments of the present invention have been described above. However, these embodiments are intended to facilitate understanding of the present invention and are not intended to limit the scope of the invention. Furthermore, the present invention can certainly be modified and altered without departing from its spirit, and the present invention includes equivalents.

[0173] 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 pulverize the pulp and shorten the fiber length, the following process is typically performed: a softener (debonding agent) such as a quaternary ammonium surfactant is added to the pulp flakes before pulverization, thereby making the pulp easier to pulverize (so-called processed pulp). However, if a softener (debonding agent) is used, it may easily hinder water absorption.

[0174] Therefore, it is preferable that the absorbent fibers constituting the absorbent core 132 of the pad 1 are configured to not contain a softener (bonding agent). This helps to suppress the decrease in the water retention performance of the absorbent core 132. In the above embodiment, since the absorbent core 132 is formed using hardwood pulp, even without the use of a softener (bonding agent), the average fiber length can be approximately 0.8 mm, resulting in an absorbent core 132 with excellent absorbency and softness.

[0175] In the above embodiment, a pad 1 with a structure in which the absorbent layer 13 is disposed at a position closer to the non-skin side than the sub-absorbent layer 12 has been described (see reference). Figure 2 (etc.), but their configuration can also be reversed in the thickness direction. For example, the sub-absorbent layer 12 can be configured to be disposed on the non-skin side in the thickness direction of the absorbent layer 13. Alternatively, it can be configured to have only the absorbent layer 13 without the sub-absorbent layer 12 in the pad 1.

[0176] Explanation of reference numerals in the attached figures

[0177] 1. Interlabial pad (pad, absorbent material)

[0178] 11 Surface layer, 11a Continuum,

[0179] 12 sub-absorption layers

[0180] 13 Absorption layer

[0181] 131 skin profile, 131a continuum,

[0182] 132 Absorbent Core

[0183] 133 non-skin side plate, 133a continuum,

[0184] 14 Backside layer, 14a Continuum,

[0185] 15-finger insert, 15-finger insert non-jointing part,

[0186] 16. Finger insertion plate joint,

[0187] 17. Back layer joint

[0188] 18. Slit

[0189] 18a First slit, 18b Second slit,

[0190] 19. Compression section

[0191] 20. Finger insertion part

[0192] 300 Crushing Evaluation Tester

[0193] 311 First sieve, 312 Second sieve, 313 Third sieve, 314 Fourth sieve, 315 Fifth sieve

[0194] 320 Vibration Device

[0195] 500 manufacturing facilities

[0196] 510 Conveying mechanism

[0197] 520 Absorbent Core Stack Mechanism

[0198] 521 Fiber Debonding Device

[0199] 521m serrated cylinder, 521mf circumferential surface, 521Ar rotating shaft,

[0200] 522 Material Supply Section, 523 Rotating Roller, 523r Recess,

[0201] 525 saw blade, 526 feed roller,

[0202] 530 sub-absorbent layer stacking mechanism,

[0203] 531 fiber unwinding device, 531m toothed cylinder,

[0204] 540 Reversing Mechanism

[0205] 550 First slit forming mechanism,

[0206] 551 cutting roller, 551f circumferential surface, 551c blade,

[0207] 552 anvil roller, 552f circumferential surface, 552d groove,

[0208] 560 Second slit forming mechanism

[0209] 561 cutting roller, 561f circumferential blade, 561c blade, 561rc circumferential blade,

[0210] 562 Anvil Roller

[0211] 570 Cut-off sealing mechanism

[0212] 580 turnaround mechanism

[0213] 590 Finger Insertion Piece Installation Mechanism

[0214] 595 Unlock the mechanism,

[0215] 595a First Roll, 595b Second Roll, 595c Third Roll

[0216] 595d Fourth Roll

[0217] F-shaped line (bent line)

[0218] PS1 pulp sheets, PS2 pulp sheets,

[0219] CR Central Region

[0220] SR end region.

Claims

1. A method for manufacturing an interlabial pad, characterized in that, The method for manufacturing the interlabial pad has the following characteristics: The defiberization process involves defibering pulp flakes containing hardwood pulp to produce pulverized pulp; and The absorbent core forming process involves aggregating the pulverized pulp to form the absorbent core. In the defiberization process, the pulp flakes are defiberized to facilitate pulp pulverization evaluation tests, which allow the pulverized pulp to pass through various sieves with different mesh sizes and 25.4 mm spacing. The proportion of fibers that did not pass through a sieve of 14 mesh or larger, relative to the total weight of the pulverized pulp being evaluated, is less than 10%, and... The proportion of the weight of fibers passing through a 60-mesh sieve is less than 20% relative to the total weight of the pulverized pulp being evaluated.

2. The method for manufacturing an interlabial pad according to claim 1, characterized in that, In the defiberization process, the defiberization amount per unit width of the pulp sheet is 7.5~60.0 kg / mh.

3. The method for manufacturing an interlabial pad according to claim 1 or 2, characterized in that, In the defiberization process, a saw-tooth cylinder with a saw blade wound around the circumference of a rotating roller is used to defiber the pulp sheet.

4. The method for manufacturing an interlabial pad according to claim 1 or 2, characterized in that, The pulverized pulp does not contain fibers that did not pass through a sieve of 14 mesh or larger during the pulp pulverization state evaluation test.

5. The method for manufacturing an interlabial pad according to claim 1 or 2, characterized in that, The method for manufacturing the interlabial pad has the following characteristics: A conveying process in which the absorbent core is conveyed along a conveying direction; A slit-forming process, wherein a slit is formed on the conveyed absorbent core; as well as The unpacking process involves unpacking the pulverized pulp that constitutes the absorbent core.

6. The method for manufacturing an interlabial pad according to claim 5, characterized in that, The unwinding process is performed after the slit-forming process.

7. The method for manufacturing an interlabial pad according to claim 6, characterized in that, The unwinding process is performed as follows: while the interlabial pad is clamped between the first roller and the second roller, it is conveyed along the conveying direction. The first roller rotates about a rotation axis orthogonal to the conveying direction. The second roller is disposed adjacent to the downstream side of the first roller in the conveying direction and rotates about a rotation axis orthogonal to the conveying direction. In the vertical direction, the position of the closest side of the portion of the circumference of the first roller that abuts against the interlabial pad is located one side further away than the position of the furthest side of the portion of the circumference of the second roller that abuts against the interlabial pad.

8. The method for manufacturing an interlabial pad according to claim 7, characterized in that, The absorbent core has a front-to-back direction and a width direction. The length of the absorbent core in the front-to-back direction is longer than its length in the width direction. In the unpacking process, the absorbent core is conveyed with the front-to-back direction aligned with the conveying direction.

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

10. The method for manufacturing an interlabial pad according to claim 8, characterized in that, The method for manufacturing the interlabial pad also includes a folding step, in which the absorbent core is folded in half using a fold line along the front-back direction. The unwinding process is performed after the folding-back process.

11. The method for manufacturing an interlabial pad according to claim 8, characterized in that, In the slit forming process, a plurality of first slits are formed along the width direction and a plurality of second slits are formed along the front-back direction. The combined length of the first slits is longer than the combined length of the second slits.

12. A labial pad comprising an absorbent core, the absorbent core being composed of pulverized pulp obtained by defiberizing pulp sheets containing broadleaf pulp, characterized in that, In the case of evaluating the pulping state by conducting pulping tests on various sieves with different mesh sizes and a 25.4 mm spacing, the pulp was subjected to a pulping state evaluation test. The proportion of fibers that did not pass through a sieve of 14 mesh or larger, relative to the total weight of the pulverized pulp being evaluated, is less than 10%, and... The proportion of the weight of fibers passing through a 60-mesh sieve is less than 20% relative to the total weight of the pulverized pulp being evaluated.

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