Underpants type paper diaper

Abstract

To provide an underpants type paper diaper which is low in rate of occurrence of defective product caused by hot-melt adhesive and exudation of the hot-melt adhesive in a manufacturing step, has few troubles caused by pulp separability and an elastic member such as rubber thread of a waist gathering part during recycling processing, and is excellent in material recycling.SOLUTION: An underpants type paper diaper 10 includes: an exterior body 20 which has a waist gathering part 28 and configures an outer shape of an underpants type paper diaper 10 when worn; and an absorbent body 40 which has a top sheet 41, a back sheet 42 and an absorbent 43, and is adhered to a skin side surface of the exterior body 20. A proportion of a second coating amount of the hot-melt adhesive used for adhering the absorbent body 40 and the exterior body 20 and the hot-melt adhesive used for the top sheet 41 of the absorbent body 40 relative to a first coating amount of the hot-melt adhesive used for the waist gathering part 28 of the exterior body 20 is between 0.3 and 1.0.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present disclosure relates to a pants-type disposable diaper. [Background technology]

[0002] Patent Document 1 discloses a pants-type absorbent article. The outer body of this pants-type absorbent article has a plurality of elastic members for forming waist-around gathers arranged in a transversely stretchable manner in the portions corresponding to the ventral side and back side (waist region, iliac region, and waist region). The plurality of elastic members are fixed by an adhesive between the outer layer sheet and the inner layer sheet constituting the outer body so as to be transversely stretchable, and are arranged intermittently in the longitudinal direction. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2022-048114 Summary of the Invention [Problem to be solved by the invention]

[0004] Currently, used disposable diapers are collected as combustible waste by local governments and either incinerated in incinerators or disposed of directly in landfills in municipalities that do not have incinerators. Incineration of disposable diapers, which contain a lot of moisture, requires a lot of energy and costs. In addition, there is a limit to the amount of land available for disposal in landfills.

[0005] The use of adult disposable diapers is increasing year by year due to the aging population, and there is a demand for the development of disposable diapers that are easy to recycle (environmentally friendly).To date, thermal recycling has been the mainstream method of recycling, and few diapers have been recycled as materials.

[0006] Disposable diapers are made from a variety of materials, including elastic thread, absorbent material, and nonwoven fabric, and hot melt adhesive is used to bond the materials that make up the diaper. Pants-type disposable diapers, in particular, contain a lot of elastic thread, and when they are broken down and processed in a recycling processing machine, the elastic thread gets tangled in the drainage pump, reducing efficiency and causing operational issues. Furthermore, if the absorbent material cannot be separated from the diaper body (exterior), the pulp and plastic cannot be separated properly, which has a negative impact on material recycling.

[0007] Therefore, the present disclosure aims to provide a pants-type disposable diaper that is excellent for material recycling, in that it has a low rate of defective products caused by hot melt adhesive and low seepage of hot melt adhesive during the manufacturing process, and in that it has few problems during recycling caused by the separability of pulp or elastic members such as rubber thread in the waist gathers. [Means for solving the problem]

[0008] In order to solve the above problems, a first aspect of the present invention is a pants-type disposable diaper that can be washed, separated, and recycled after use, comprising an outer body having a waist gathered portion and that forms the outer shape of the pants-type disposable diaper when worn, an absorbent body having a liquid-permeable top sheet, a liquid-impermeable back sheet, and an absorbent body disposed between the top sheet and the back sheet and adhered to the skin-facing side of the outer body, wherein the ratio of a second coat amount of hot melt adhesive used to bond the absorbent body to the outer body and the hot melt adhesive used for the top sheet of the absorbent body to a first coat amount of hot melt adhesive used in the waist gathered portion of the outer body is 0.3 or more and 1.0 or less.

[0009] A second aspect of the present invention is the pants-type disposable diaper of the first aspect, wherein the first coating amount is 0.75 g or more and 1.05 g or less, and the second coating amount is 0.75 g or more and 0.35 g or less. [Effects of the Invention]

[0010] According to the present disclosure, it is possible to provide a pants-type disposable diaper that is excellent for material recycling, in which the rate of defective products caused by hot melt adhesive and seepage of hot melt adhesive is low during the manufacturing process, and in which problems caused by pulp separability and elastic members such as rubber thread in the waist gather portion are reduced during recycling processing. [Brief explanation of the drawings]

[0011] [Figure 1] 1 is a front perspective view of a pants-type disposable diaper according to an embodiment of the present invention; [Figure 2] 2 is a plan view of the pants-type disposable diaper of FIG. 1 in an unfolded state, seen from the skin side. FIG. [Figure 3] FIG. 3 is a schematic cross-sectional view taken along the line III-III in FIG. 2. [Figure 4] FIG. 4 is a schematic cross-sectional view taken along the line IV-IV in FIG. 2. [Figure 5] FIG. 4 is an enlarged view of a portion V in FIG. 3. [Figure 6] FIG. 1 is an explanatory diagram of a rotary drum device used in a recycling process. DETAILED DESCRIPTION OF THE INVENTION

[0012] Hereinafter, a pants-type disposable diaper according to one embodiment of the present invention will be described with reference to the drawings.

[0013] Fig. 1 is a perspective view of the appearance of a pants-type disposable diaper according to one embodiment of the present invention, seen from the front. Fig. 2 is a plan view of the pants-type disposable diaper of Fig. 1 in an unfolded state, seen from the skin side. Fig. 3 is a schematic cross-sectional view taken along the line III-III in Fig. 2. Fig. 4 is a schematic cross-sectional view taken along the line IV-IV in Fig. 2. Fig. 5 is an enlarged view of part V in Fig. 3. Note that each drawing does not define the relative sizes of the components of the pants-type disposable diaper, and the dimensions of each component can be appropriately selected from a wide range depending on the purpose of the pants-type disposable diaper, the age of the intended wearer, etc.

[0014] In this specification, "wearing a pants-type disposable diaper" refers to the state in which the pants-type disposable diaper is worn on the body, regardless of whether the diaper absorbs bodily fluids before, during, or after the absorption of bodily fluids. Furthermore, "front side" refers to the direction that corresponds to the wearer's stomach when the pants-type disposable diaper is worn, and "rear side" refers to the direction that corresponds to the wearer's back. Furthermore, "upper side" refers to the direction that corresponds to the wearer's head when the pants-type disposable diaper is worn, and "lower side" refers to the direction that corresponds to the wearer's feet when the pants-type disposable diaper is worn. Furthermore, "left-right direction" refers to the left-right direction as seen from the wearer facing forward. Furthermore, the longitudinal direction of each component of the pants-type disposable diaper refers to the longitudinal direction (direction along the front and back) of the pants-type disposable diaper in its unfolded state (as shown in FIG. 2), which is the direction indicated by arrow X in each drawing. Furthermore, the width direction of each component of the pants-type disposable diaper refers to the direction perpendicular to the longitudinal direction (direction along the left and right) of the pants-type disposable diaper in its unfolded state, which is the direction indicated by arrow Y in each drawing. The thickness direction of each component of a pants-type disposable diaper refers to the direction in which the components are stacked, which is the direction indicated by arrow Z in each drawing. The skin side of each component of a pants-type disposable diaper refers to the thickness direction toward the wearer's skin when the pants-type disposable diaper is worn, and the non-skin side refers to the thickness direction opposite the skin side. Body fluids refer to liquids excreted from the body to the outside, such as urine, blood, and water in loose stools.

[0015] <Pants-type disposable diapers> As shown in Figures 1 to 5, the pants-type disposable diaper 10 of this embodiment is a pants-type disposable diaper 10 that can be washed and separated after use and recycled, and comprises an outer body 20 that forms the external shape of the pants-type disposable diaper 10, and an absorbent body 40 that is supported by the outer body 20 and mainly absorbs body fluids.

[0016] <Exterior body> 1 and 2, the exterior body 20 is a component that constitutes the outer shape of the pants-type disposable diaper 10, and has a front waist region 21 that is located in front of the wearer's abdomen when worn, a rear waist region 22 that is located behind the wearer's back, and a crotch region 23 that is located between the wearer's legs. The absorbent main body 40 is mainly disposed on the inner side (skin side) of the crotch region 23 of the exterior body 20, but a part of it (front and rear end portions) may extend to the front waist region 21 or the rear waist region 22 of the exterior body 20.

[0017] As shown in FIGS. 1 to 5, the exterior body 20 is formed by a nonwoven fabric sheet 24. In this embodiment, the exterior body 20 is formed by laminating a plurality of nonwoven fabric sheets 24. The nonwoven fabric sheet 24 can be a nonwoven fabric such as a thermal-bonded nonwoven fabric, an air-through nonwoven fabric, or a spun-bonded nonwoven fabric, preferably an air-through nonwoven fabric or a spun-bonded nonwoven fabric made of a thermoplastic resin such as polypropylene, polyester, or polyethylene. Note that while FIG. 3 illustrates two nonwoven fabric sheets 24 stacked together, the number of stacked nonwoven fabric sheets 24 is not limited to two, and three or more nonwoven fabric sheets may be stacked.

[0018] As shown in FIG. 2, the exterior body 20 in its unfolded state has a bilaterally symmetrical shape. The front waistline region 21 and the back waistline region 22 each have a side seal 25 extending longitudinally at both widthwise ends. The front waistline region 21 and the back waistline region 22 are spaced apart longitudinally. The crotch region 23 is a region located between the front waistline region 21 and the back waistline region 22. By fastening both widthwise ends of the front waistline region 21 and both widthwise ends of the back waistline region 22 to each other with the side seal 25, the exterior body 20 is formed into a pants-like shape as a whole, as shown in FIG. 1, with both left and right ends of the front waistline region 21 and the back waistline region 22 continuing together. Note that in the following description, the direction of the exterior body 20 refers to the direction when worn by a wearer.

[0019] As shown in FIG. 1 , the exterior body 20 has a waist opening 26 at the upper parts of the front waistline region 21 and the back waistline region 22, and leg openings 27a, 27b on both the left and right sides of the crotch region 23. The waist opening 26 is the portion through which the wearer's torso passes when worn, and is formed by the upper edge portions of both the front waistline region 21 and the back waistline region 22. A waist gather portion 28 that is stretchable in the circumferential direction is provided near the lower part of the waist opening 26. The left and right leg openings 27a, 27b are portions through which the wearer's legs pass, and are formed by both left and right end edges of the crotch region 23. The exterior body 20 of this embodiment has leg gather portions 29 that are stretchable in the circumferential direction near the left and right leg openings 27a, 27b. Furthermore, the outer body 20 of this embodiment has fit gathers 30 that are stretchable in the circumferential direction (waist direction) below the waist gathers 28 in the front waistline region 21 and the back waistline region 22. In this embodiment, the outer body 20 is provided with leg gathers 29 and fit gathers 30, but this is not limited thereto, and the leg gathers 29 and fit gathers 30 may not be provided.

[0020] As shown in Figures 2 and 4, in this embodiment, the nonwoven fabric sheet 24 constituting the outer casing 20 includes two main sheets 24a, 24b extending integrally from the front waistline region 21 through the crotch region 23 to the back waistline region 22, and two auxiliary sheets 24c, 24d (four on each side) provided on each longitudinal side. The main sheets 24a, 24b are stacked together, with the main sheet 24a located on the non-skin side and the main sheet 24b located on the skin side thereof. The auxiliary sheets 24c, 24d are located on the skin side of the main sheets 24a, 24b in the front waistline region 21 and the back waistline region 22. The auxiliary sheets 24c, 24d are stacked together, with the auxiliary sheet 24c located on the non-skin side and the auxiliary sheet 24d located on the skin side thereof. The upper end sides (outer end sides in the longitudinal direction) of the auxiliary sheets 24c, 24d are fixed to the main sheets 24a, 24b, and the lower end sides (inner end sides in the longitudinal direction) of the auxiliary sheets 24c, 24d are fixed to the skin side of the outer end parts in the longitudinal direction of the absorbent main body 40. In other words, the auxiliary sheets 24c, 24d on both sides in the longitudinal direction are sheets that support both end parts in the longitudinal direction of the absorbent main body 40 from the skin side. Note that the nonwoven fabric sheets 24 that constitute the exterior body 20 are not limited to the above four sheets.

[0021] (gathered waist) 1, 2, and 4, the waist gathers 28 have a plurality of elastic members 31 arranged near the waist openings 26 in the front waistline region 21 and the back waistline region 22. Note that while FIG. 4 shows a cross section of the front waistline region 21, the cross section of the back waistline region 22 has a substantially similar configuration. The waist gathers 28 provided in the front waistline region 21 and the back waistline region 22 are arranged symmetrically in the front and back and have a substantially similar configuration. Therefore, the following description will focus on the waist gathers 28 in the front waistline region 21, and a description of the back waistline region 22 will be omitted.

[0022] The multiple elastic members 31 of the waist gathered portion 28 are elastic members that extend in the circumferential direction of the waist opening 26, are arranged at the upper ends of the front waistline region 21 and the back waistline region 22, and are joined to the nonwoven fabric sheet 24 of the exterior body 20. As the elastic members 31, for example, stretchable thread-like elastic members (thread rubber) such as natural rubber, synthetic rubber, polyurethane, etc. can be used as appropriate, and their thickness is preferably 500 dtex or more and 2000 dtex or less.

[0023] The multiple elastic members 31 and the nonwoven fabric sheet 24 of the exterior body 20 are bonded to one another with a hot melt adhesive. That is, the hot melt adhesive is used in the waist gathered portion 28 of the exterior body 20. As shown in FIG. 4 , the hot melt adhesive used in the waist gathered portion 28 is applied to a first application area 32 and a second application area 33, which will be described later, to bond the multiple elastic members 31 to the exterior body 20.

[0024] (hot melt adhesive) Examples of hot melt adhesives used in the pants-type disposable diaper 10 include SBC (styrene block copolymer) hot melt adhesives, EVA (ethylene vinyl acetate) hot melt adhesives, and olefin hot melt adhesives. Hot melt adhesives can be applied by known methods such as the curtain coating method or spiral method, in which molten hot melt adhesive is applied from a nozzle in a non-contact manner, or the slot method, in which the adhesive is applied in a contact manner.

[0025] (First application area of ​​hot melt adhesive) 4, the first application region 32 is a region where hot melt adhesive is applied to directly bond the plurality of elastic members 31 to the nonwoven fabric sheet 24 of the exterior body 20, and is where the plurality of elastic members 31 are arranged. In this embodiment, the plurality of elastic members 31 are arranged near the waist opening 26 between two auxiliary sheets 24c, 24d of the nonwoven fabric sheet 24 that constitutes the exterior body 20. In other words, the first application region 32 is a region where hot melt adhesive is applied to directly bond the plurality of elastic members 31 to the two auxiliary sheets 24c, 24d.

[0026] (Second application area of ​​hot melt adhesive) As shown in FIG. 4 , the second application area 33 is an area where hot melt adhesive is applied to more firmly secure the multiple elastic members 31 to the exterior body 20, and is an area that overlaps the first application area 32. In this embodiment, the second application area 33 is an area where hot melt adhesive is applied to fold the outer longitudinal edge of the main sheet 24a of the nonwoven fabric sheet 24 toward the skin side and secure it to the auxiliary sheet 24d. This folded outer longitudinal edge of the main sheet 24a functions as an end seal portion that closes the outer longitudinal edge of the exterior body 20. The folded outer longitudinal edge of the main sheet 24a is adhered to the auxiliary sheet 24d at a position that overlaps the first application area 32 from the skin side. In other words, the second application area 33 is arranged so as to overlap the first application area 32 from the skin side. As a result, the multiple elastic members 31 are more firmly adhered to the exterior body 20 not only by the hot melt adhesive applied to the first application area 32 but also by the hot melt adhesive applied to the second application area 33. In this way, the hot melt adhesive used in the waist gathered portion 28 is applied to the first application area 32 and the second application area 33, and adheres the multiple elastic members 31 to the exterior body 20.

[0027] (Leg gathering part) The leg gathers 29 have a plurality of elastic members 34 arranged near the left and right leg openings 27a, 27b. The elastic members 34 extend circumferentially around the left and right leg openings 27a, 27b. The elastic members 34 and the nonwoven fabric sheet 24 of the outer body 20 are bonded to each other with a hot melt adhesive. As shown in FIG. 3 , in this embodiment, the elastic members 34 are arranged between the main sheets 24a, 24b in the crotch region 23 of the outer body 20 and are bonded to the main sheets 24a, 24b with a hot melt adhesive. The elastic members 34 of the leg gathers 29 may be the same as or different from the elastic members 31 of the waist gathers 28.

[0028] (Fitted gathers) The fit gather portion 30 has a plurality of elastic members 35 arranged in the front waistline region 21 and the back waistline region 22 below the waist gather portion 28. The plurality of elastic members 35 extend in the circumferential direction (waistline direction). The plurality of elastic members 35 and the nonwoven fabric sheet 24 of the exterior body 20 are bonded to each other with a hot melt adhesive. As shown in FIG. 4 , in this embodiment, the plurality of elastic members 35 are arranged between the main sheets 24a, 24b in the front waistline region 21 and the back waistline region 22 of the exterior body 20 and are bonded to the main sheets 24a, 24b with a hot melt adhesive. The elastic members 34 of the fit gather portion 30 may be the same as or different from the elastic members 31 of the waist gather portion 28.

[0029] <Absorbent body> As shown in FIGS. 3 to 5 , the absorbent main body 40 includes a liquid-permeable top sheet 41 on the skin side, a liquid-impermeable back sheet 42 on the non-skin side, and an absorber 43 disposed between the top sheet 41 and the back sheet 42. Furthermore, the absorbent main body 40 of this embodiment includes three-dimensional gathers 44, absorbent paper 45, and a liquid-diffusion sheet 46. The absorbent main body 40 is disposed on the skin-side surface of the outer body 20, mainly in the crotch region 23, so as to extend from the front waistline region 21 toward the rear waistline region 22. The absorbent main body 40 is adhered to the skin-side surface of the outer body 20 with a hot melt adhesive, as described below. While the absorbent main body 40 of this embodiment includes the three-dimensional gathers 44, the absorbent paper 45, and the liquid-diffusion sheet 46, the present invention is not limited thereto, and the absorbent main body 40 may not include at least one of the three-dimensional gathers 44, the absorbent paper 45, and the liquid-diffusion sheet 46.

[0030] (Top sheet) The top sheet 41 may be formed from a liquid-permeable substrate that allows bodily fluids to move toward the absorbent body 43. Examples of the substrate include nonwoven fabrics such as thermal-bonded nonwoven fabrics, composite nonwoven fabrics formed by laminating thermal-bonded nonwoven fabrics and spun-bonded nonwoven fabrics, apertured films such as apertured polyethylene films, foamed films such as polyethylene foam and urethane foam, and composite sheets formed by laminating these. The surface of the top sheet 41 may be embossed or perforated to improve liquid permeability. Any known method can be used for embossing or perforating the top sheet 41 without limitation. Furthermore, to reduce irritation to the skin, the top sheet 41 may contain lotions, antioxidants, anti-inflammatory ingredients, pH adjusters, antibacterial agents, moisturizers, and the like. The shape of the top sheet 41 is not particularly limited, but may be any shape that covers the absorbent body 43 to guide bodily fluids toward the absorbent body 43 without leakage.

[0031] (back seat) The backsheet 42 may be formed using a liquid-impermeable substrate to prevent leakage of bodily fluids held in the absorber 43 to the non-skin side, and may be formed from a material such as a resin film or a composite sheet formed by laminating a resin film and a nonwoven fabric. The nonwoven fabric used in the composite sheet may be made by any method, and examples thereof include composite nonwoven fabrics formed by laminating multiple identical and / or different nonwoven fabrics, such as spunbond nonwoven fabric, meltblown nonwoven fabric, spunbond nonwoven fabric / meltblown nonwoven fabric, and spunbond nonwoven fabric / meltblown nonwoven fabric / spunbond nonwoven fabric, as well as composite materials thereof. Examples of resin films include polyester, polyvinyl alcohol, polyethylene, polypropylene, and composite films of polyethylene and polypropylene.

[0032] The back sheet 42 is preferably breathable to prevent stuffiness during wear. To provide breathability to the back sheet 42, for example, a filler may be blended into the base resin film or the back sheet 42 may be embossed. An example of the filler is calcium carbonate, and the blending method can be any known method without limitation. For example, a porous (breathable) resin film can be obtained by kneading a resin and a filler, forming the resulting kneaded product into a film, and removing the filler from the resulting film.

[0033] (absorbent) The absorbent body 43 includes a body fluid absorbing material, and preferably includes absorbent fibers as a base material and a body fluid absorbing material held by the absorbent fibers.

[0034] The absorbent fiber used as the base material of the absorber 43 is not particularly limited as long as it is one generally used in absorbent articles such as sanitary napkins, diapers, and urine absorption pads, and may be formed from materials such as fluff pulp, cotton, rayon, acetate, tissue, absorbent paper, and hydrophilic nonwoven fabric. Among these, fluff pulp is preferably used from the viewpoint of absorbency. Examples of fluff pulp include wood pulp, synthetic fiber, polymer fiber, and non-wood pulp that have been defibrated into a cotton-like state.

[0035] The body fluid absorbing material of the absorber 43 is not particularly limited as long as it can absorb and retain body fluids, and examples thereof include super absorbent polymer (SAP).

[0036] The absorbent body 43 preferably contains absorbent fibers and superabsorbent polymers, and examples of its composition include those formed by mixing SAP particles into absorbent fibers, and SAP sheets in which SAP particles are fixed between the fibers in the raised parts of absorbent fibers.

[0037] (absorbent paper) The absorbent paper 45 wraps the entire absorbent body 43 from the viewpoints of preventing SAP particles from falling off and stabilizing the shape of the absorbent body 43. The base material of the absorbent paper 45 may be any hydrophilic material, such as tissue, absorbent paper, or hydrophilic nonwoven fabrics such as air-laid nonwoven fabrics. Among hydrophilic nonwoven fabrics, hydrophilic nonwoven fabrics such as thermal-bonded nonwoven fabrics, spun-bonded nonwoven fabrics, air-through nonwoven fabrics, and pulp-containing nonwoven fabrics are more preferred, with tissue paper (crepe paper) and spun-bonded nonwoven fabrics that have been hydrophilically treated as necessary being even more preferred. When multiple absorbent papers 45 are provided, the base materials of the absorbent papers 45 may be the same or different.

[0038] (liquid diffusion sheet) The liquid diffusion sheet 46 is a liquid-permeable sheet for diffusing body fluid from the top sheet 41 side and guiding it to the absorbent body 43 side, and is disposed between the top sheet 41 and the absorbent body 43. Examples of the liquid diffusion sheet 46 include nonwoven fabrics such as air-through nonwoven fabrics, point-bonded nonwoven fabrics, spunbonded nonwoven fabrics, and melt-blown nonwoven fabrics, as well as composite nonwoven fabrics obtained by laminating spunbond / melt-blown or spunbond / melt-blown / spunbond. There are no particular restrictions on the shape of the liquid diffusion sheet 46, but in order to favorably diffuse liquid from the top sheet 41 side into the absorbent body 43, it is preferable that the liquid diffusion sheet 46 has a shape that completely covers the surface of the absorbent body 43, or in order to reduce costs, it is preferable that the liquid diffusion sheet 46 has a shape that partially but not completely covers the surface of the absorbent body 43.

[0039] (3D gathers) The standing gathers 44 are provided to prevent, for example, side leakage of bodily fluids, etc. The standing gathers 44 of this embodiment include a standing gather sheet 44a and thread-like elastic members 44b.

[0040] For example, various nonwoven fabrics can be used for the three-dimensional gathered sheet 44a of the three-dimensional gathers 44. One widthwise end of the three-dimensional gathered sheet 44a is fixed along the longitudinal direction to the vicinity of both widthwise ends of the backsheet 42, a middle portion in the widthwise direction is fixed along the longitudinal direction to the vicinity of both widthwise ends of the topsheet 41, and the other widthwise end is a free end.

[0041] The thread-like elastic members 44b of the three-dimensional gathers 44 can be made of, for example, natural rubber, synthetic rubber, polyurethane, or other suitable thread-like elastic members. The thread-like elastic members 44b are arranged along the longitudinal direction near the other end (free end) in the width direction of the three-dimensional gathered sheet 44a, and provide stretchability and upstanding properties to the other end (free end) of the three-dimensional gathered sheet 44a. The other end of the three-dimensional gathered sheet 44a, which has stretchability and upstanding properties, is stretchable and deformable to fit the wearer's body shape.

[0042] (Third application area of ​​hot melt adhesive) As shown in FIGS. 3 to 5 , the absorbent main body 40 is adhered to the skin side of the outer body 20 with a hot melt adhesive. That is, a third application area 47, where the hot melt adhesive is applied, is provided between the non-skin side of the absorbent main body 40 and the skin side of the outer body 20. The third application area 47 is an area where the hot melt adhesive is applied to directly adhere the non-skin side of the absorbent main body 40 to the skin side of the outer body 20. In this embodiment, the third application area 47 is provided between the skin side of the main sheet 24b of the nonwoven fabric sheet 24 constituting the outer body 20 and the non-skin side of the absorbent main body 40. Note that the third application area 47 is not limited to the area between the skin side of the main sheet 24b and the non-skin side of the absorbent main body 40, but may be any area that can adhere the non-skin side of the absorbent main body 40 to the skin side of the outer body 20.

[0043] (Fourth application area of ​​hot melt adhesive) Furthermore, the top sheet 41 of the absorbent main body 40 is adhered to other components of the absorbent main body 40 (for example, the absorber 43, the back sheet 42, etc.) with a hot melt adhesive. In this embodiment, the hot melt adhesive is applied to substantially the entire non-skin side of the top sheet 41, and the top sheet 41 is adhered to other components opposing the non-skin side of the top sheet 41 by the hot melt adhesive. That is, a fourth application area 48 to which the hot melt adhesive is applied is provided on the non-skin side of the top sheet 41 (substantially the entire non-skin side in this embodiment) (see FIGS. 3 and 5). The fourth application area 48 is an area to which the hot melt adhesive is applied to adhere the top sheet 41 to other components of the absorbent main body 40. Note that the fourth application area 48 is not limited to substantially the entire non-skin side of the top sheet 41, but may be a partial area of ​​the non-skin side of the top sheet 41.

[0044] (Fifth application area of ​​hot melt adhesive) Furthermore, the top sheet 41 of the absorbent main body 40 is adhered to both longitudinal ends of the absorbent body 43 and both longitudinal ends of the back sheet 42 with a hot melt adhesive. That is, on the non-skin side of the top sheet 41, fifth application areas 49, to which hot melt adhesive is applied, are provided from areas facing both longitudinal ends of the absorbent body 43 to areas facing both longitudinal ends of the back sheet 42 (see FIGS. 1 and 4). The fifth application areas 49 are areas where hot melt adhesive is applied to adhere both longitudinal ends of the top sheet 41 to the absorbent body 43 and the back sheet 42. The fifth application areas 49 are provided on both longitudinal ends of the top sheet 41 so as to extend along the width direction. By adhering both longitudinal ends of the top sheet 41 to the absorbent body 43 and the back sheet 42, when body pressure is applied to the absorbent body 43 in a swollen state after absorbing moisture, it is possible to prevent the contents of the absorbent body 43, such as SAP and fluff pulp, from leaking out from both longitudinal ends of the absorbent main body 40. In this embodiment, both longitudinal ends of the absorbent body 43 are adhered to the top sheet 41 via the absorbent paper 45 and the liquid diffusion sheet 46 by hot melt adhesive applied to the fifth application region 49.

[0045] In this way, the hot melt adhesive used in the top sheet 41 is applied to the fourth application area 48 and the fifth application area 49 to adhere the top sheet 41 to other components of the absorbent body 40.

[0046] (Coating amount of hot melt adhesive) Next, the coating amount of the hot melt adhesive will be described. The coating amount of the hot melt adhesive is the amount of hot melt adhesive applied during the manufacture of the pants-type disposable diaper 10. In the following description, the coating amount (first coating amount) A of the hot melt adhesive used in the waist gathered portion 28 of the exterior body 20 (hereinafter sometimes simply referred to as "coating amount A") is the coating amount of the hot melt adhesive applied to the first coating area 32 and the second coating area 33. The coating amount B of the hot melt adhesive used to bond the absorbent main body 40 and the exterior body 20 (hereinafter sometimes simply referred to as "coating amount B") is the coating amount of the hot melt adhesive applied to the third coating area 47. The coating amount C of the hot melt adhesive used in the top sheet 41 (hereinafter sometimes simply referred to as "coating amount C") is the coating amount of the hot melt adhesive applied to the fourth coating area 48 and the fifth coating area 49. In addition, the coating amount (second coating amount) D (hereinafter sometimes simply referred to as "coating amount D") of the hot melt adhesive used to bond the absorbent body 40 and the outer body 20 and the hot melt adhesive used on the top sheet 41 of the absorbent body 40 is the sum of the coating amount B and the coating amount C.

[0047] The coating weight A of the hot melt adhesive used in the waist gathered portion 28 of the exterior body 20 is preferably 0.75 g or more and 1.05 g or less. The coating weight D of the hot melt adhesive used to bond the absorbent main body 40 to the exterior body 20 and the hot melt adhesive used in the top sheet 41 of the absorbent main body 40 is preferably 0.75 g or more and 0.35 g or less. Setting the coating weight A and the coating weight D within the above ranges prevents the elastic members 31 of the waist gathered portion 28 from becoming entangled in the drain pump 112 (see FIG. 6 ) of the rotary drum device 100, which is a recycling processor, when the pants-type disposable diaper 10 is recycled, as described below. Furthermore, the absorbent main body 40 becomes more easily detached from the exterior body 20 during recycling, improving separation of the absorbent fiber (pulp) that serves as the base material for the absorbent body 43.

[0048] (Hot melt adhesive coating amount ratio) The ratio of the coating weight D to the coating weight A (coating weight D / coating weight A) is 0.3 or more and 1.0 or less. The ratio of the coating weight D to the coating weight A is expressed as (coating weight B + coating weight C) / coating weight A. If the value expressed as coating weight D / coating weight A is less than 0.3, the coating weight of the hot melt adhesive used in the absorbent main body 40 will be significantly less than the coating weight A of the hot melt adhesive used in the waist gathered portion 28. This weakens the adhesive strength of the absorbent main body 40, and the absorbent core 43 may become displaced from its correct position due to movements during wear, causing urine leakage or the absorbent core 43 to become distorted, resulting in a poor wearing comfort. Conversely, if the adhesive strength of the absorbent main body 40 is adjusted appropriately, the waist gathered portion 28 will become too stiff, resulting in a poor wearing comfort. On the other hand, if the value expressed by coating amount D / coating amount A is set to be greater than 1.0, the coating amount of the hot melt adhesive used in the absorbent main body 40 will be greater than the coating amount A of the hot melt adhesive used in the waist gathered portion 28. For this reason, when the pants-type disposable diaper 10 is recycled as described below, the decomposition of the absorbent main body 40 and the decomposition of the waist gathered portion 28 will proceed in the same manner, which may cause problems such as the elastic members 31 of the waist gathered portion 28 flowing out during drainage and becoming tangled in the drainage pump 112 or the agitator (rotary drum device 100).

[0049] (Method for measuring the coating weight ratio of hot melt adhesives) The ratio of the coating amount D to the coating amount A of the hot melt adhesive used in manufacturing the pants-type disposable diaper 10 is determined from the amount A' (hereinafter sometimes simply referred to as "amount A'") of the hot melt adhesive in the waist gathered portion 28, which is detected from the finished pants-type disposable diaper 10 using a method described below, and the amount D' (hereinafter sometimes simply referred to as "amount D'") of the hot melt adhesive in the bonded portion between the absorbent main body 40 and the outer body 20 and in the top sheet 41. Although the amounts A' and D' tend to be smaller than the coating amounts A and D (A≧A', D≧D'), there is a correlation between the ratio of the amount A' to the coating amount A and the ratio of the amount D' to the coating amount D. Therefore, the ratio of the coating amount D to the coating amount A can be measured by determining the ratio of the amount D' to the amount A'. Note that amount A' is the amount of hot melt adhesive detected from the first application area 32 and the second application area 33, and amount D' is the amount of hot melt adhesive detected from the third application area 47, the fourth application area 48, and the fifth application area 49.

[0050] The amounts A' (g) and D' (g) can be measured by dissolving the hot melt adhesive (hereinafter simply referred to as "dissolution") using a solvent (industrial cleaning agent, trade name: Finesolve (Sankyo Chemical Co., Ltd.)) and then measuring the weight difference between the sample before and after dissolution. To measure the amounts A' and D', first, 100 ml of undiluted Finesolve TH at room temperature is placed in a 200 ml beaker. Next, samples are prepared for each position. The sample for detecting the amount A' is obtained by cutting out the portions corresponding to the first and second application areas 32 and 33 to a size of 3 cm x 5 cm. Alternatively, if possible, the sample for detecting the amount A' may be obtained by cutting out the portions corresponding to the first application area 32 to a size of 3 cm x 5 cm and the portions corresponding to the second application area 33 to a size of 3 cm x 5 cm. The samples for detecting the amount D' are a portion corresponding to the third application area 47 cut to a size of 3 cm x 5 cm, a portion corresponding to the fourth application area 48 cut to a size of 3 cm x 5 cm, and a portion corresponding to the fifth application area 49 cut to a size of 3 cm x 5 cm. Next, the weight of each sample before dissolution is measured. Next, each sample is immersed in the beaker containing the solvent and stirred with a magnetic stirrer at a rotation speed of 300 rpm for 3 minutes. Next, the sample is removed from the beaker, rinsed with Finesolve TH for rinsing, dried, and then the weight of the sample after dissolution is measured. Next, the difference in weight of the sample before and after dissolution is calculated. This difference (the amount (g) lost after dissolution compared to before dissolution) is used to calculate the weight of 15 cm of sample. 2 This is the amount of hot melt adhesive contained per coating. Finally, the amount A' and the amount D' are detected according to the area of ​​each coating region. It is preferable to perform such measurements using samples at three or more locations in each coating location (first coating region 32, second coating region 33, third coating region 47, fourth coating region 48, and fifth coating region 49).

[0051] (Recycling process) Next, a description will be given of the recycling process of used pants-type disposable diapers 10. Fig. 6 is an explanatory diagram of a rotary drum device used in the recycling process.

[0052] The recycling process of used pants-type disposable diapers 10 of this embodiment is carried out using an agitator, for example, a rotary drum device 100. This rotary drum device 100 is applicable to various sanitary products, such as urine absorption pads, that have a synthetic resin film portion and a liquid-absorbent portion attached to the film portion.

[0053] As shown in Fig. 6, rotary drum device 100 includes cylindrical water tub 102 as a water tub portion disposed within casing 101, rotary drum 103 disposed within water tub 102, and motor 104 for rotating rotary drum 103. A large number of small holes are formed on the circumferential surface of rotary drum 103. Blades for tearing various types of bags may be provided on the inner circumferential surface of rotary drum 103.

[0054] An opening 105 is provided on one end surface of the casing 101, and an openable door 106 that can open and close the opening 105 is attached to the casing 101. The water tub 102 and the rotating drum 103 are arranged with the cylindrical axis direction in the horizontal direction (or in an oblique direction that is higher toward the opening 105 side).

[0055] Water tub 102 and motor 104 are supported by support members (not shown) on casing 101. Rotating drum 103 is connected to motor 104 by shaft 107. Shaft 107 is supported on water tub 102 by bearings (not shown).

[0056] A water supply pipe 108 for supplying clean water such as tap water is connected to the top of the water tank 102. A drain pit 109 is provided at the bottom of the water tank 102, and a drain pipe 110 is connected to the drain pit 109. A drain valve 111 and a drain pump 112 are provided on the drain pipe 110. By closing the drain valve 111, water can be stored in the water tank 102, and by opening it, water can be drained from the water tank 102.

[0057] When using this rotary drum device 100 to dispose of used pants-type disposable diapers 10, the door 106 is opened, the used pants-type disposable diapers 10 and the disposal chemicals are placed into the rotary drum 103, and then the door 106 is closed. After a predetermined amount of water is supplied from the water supply pipe 108 into the water tub 102, the rotary drum 103 is rotated by the motor 104. In this way, the used pants-type disposable diapers 10 are disposed of. The motor 104 may be rotated in only one direction, or may be rotated back and forth (forward and reverse).

[0058] After a predetermined time (for example, 0.01 to 5 hours, particularly 0.08 to 2 hours) has elapsed and the treatment has been sufficiently carried out, the drain valve 111 is opened to drain the water. At this time, the rotating drum 103 may be rotated at high speed by the motor 104 to dehydrate the water by centrifugal force.

[0059] Thereafter, if necessary, water may be poured into the water tank 102 from the water supply pipe 108 to rinse away any residue in the rotary drum 103. This rinsing may be water pouring rinsing or pool rinsing.

[0060] After rinsing is complete, the door 106 is opened and the contents (recovered plastic) are removed and sent to the next processing step.

[0061] In addition, a drying mechanism using hot air, like a rotary drum washing machine, may be provided, in which case the contents can be dried after rinsing. Also, the temperature of the hot air may be increased to heat and sterilize the contents.

[0062] In this way, when recycling the pants-type disposable diaper 10 according to this embodiment, the used pants-type disposable diaper 10, a chemical for treating the moisture absorbent, and water are placed in a rotary drum device 100, and the used pants-type disposable diaper 10 is sterilized, decomposed, and separated.

[0063] The chemical used to treat the moisture absorbent contains a component that removes moisture (dehydrates) from the superabsorbent polymer (SAP) contained in the pants-type disposable diaper 10. This component preferably contains a cation (sodium, calcium, magnesium), an organic acid (citric acid, oxalic acid), or an inorganic acid (nitric acid, sulfuric acid, hydrochloric acid). Calcium sources that can be used include slaked lime, calcium chloride, etc. The chemical may also contain a disinfectant component for sterilization. There are no particular restrictions on the disinfectant component, but inexpensive ones include calcium hypochlorite (bleaching powder).

[0064] In the pants-type disposable diaper 10 configured as described above, the ratio of the coating amount D of the hot melt adhesive used to bond the absorbent main body 40 and the exterior body 20 and the hot melt adhesive used in the top sheet 41 of the absorbent main body 40 to the coating amount A of the hot melt adhesive used in the waist gathered portion 28 is 0.3 or more and 1.0 or less. This increases the coating amount A of the hot melt adhesive used in the waist gathered portion 28, thereby strengthening the adhesion of the elastic members 31, such as rubber thread, in the waist gathered portion 28 and preventing the elastic members 31 from leaking out during recycling.

[0065] Furthermore, if the coating amount A of the hot melt adhesive used in the waist gathered portion 28 is too large, the hot melt adhesive may seep out of the nonwoven fabric sheet 24 of the outer casing 20 during the manufacturing process, causing the front and back waist regions 21 and 22 of the waist opening 26 to stick together. If the front and back waist regions 26 stick together, the solidified hot melt adhesive may crunch when the waist opening 26 is opened to put on the pants-type disposable diaper 10, potentially affecting the feel of use. In the pants-type disposable diaper 10 configured as described above, the ratio of the coating amount D to the coating amount A of the hot melt adhesive is 0.3 to 1.0, which makes it possible to reduce the coating amount A of the hot melt adhesive used in the waist gathered portion 28, thereby preventing the front and back waist regions 26 from sticking together during the manufacturing process and reducing the rate of defective products caused by hot melt adhesive.

[0066] Furthermore, since the ratio of the coating amount D of the hot melt adhesive to the coating amount A is 0.3 or more and 1.0 or less, it is possible to reduce the coating amount B of the hot melt adhesive used to bond the absorbent main body 40 and the exterior body 20. This makes it possible to easily remove the absorbent main body 40 from the exterior body 20 during recycling processing.

[0067] Furthermore, since the ratio of the coating amount D of the hot melt adhesive to the coating amount A is 0.3 or more and 1.0 or less, it is possible to reduce the coating amount C of the hot melt adhesive used in the top sheet 41. This also improves the separation of the absorbent fiber (pulp) that serves as the base material of the absorbent body 43 during recycling processing.

[0068] Furthermore, if the coating amount B of the hot melt adhesive used to bond the absorbent main body 40 and the exterior body 20 is too small, the absorbent main body 40 may shift from the desired position on the exterior body 20 or peel off from the exterior body 20 during the manufacturing process, which may increase the rate of defective products. In the pants-type disposable diaper 10 configured as described above, the ratio of the coating amount D to the coating amount A of the hot melt adhesive is 0.3 or more and 1.0 or less, so that the coating amount B of the hot melt adhesive used to bond the absorbent main body 40 and the exterior body 20 can be appropriately set, thereby reducing the rate of defective products.

[0069] Therefore, according to this embodiment, the rate of defective products caused by hot melt adhesive and seepage of hot melt adhesive is low during the manufacturing process, and during the recycling process, problems caused by the separability of pulp and elastic members such as rubber thread in the waist gathered portion 28 are few, making it possible to provide a pants-type disposable diaper 10 that is excellent for material recycling.

[0070] Although the present invention has been described above based on the above embodiment, the present invention is not limited to the content of the above embodiment, and can be modified as appropriate without departing from the scope of the present invention. In other words, all other embodiments, examples, operational techniques, etc. made by those skilled in the art based on this embodiment are naturally included in the scope of the present invention. [Example]

[0071] The present embodiment will be described in more detail below with reference to examples and comparative examples, but the present invention is not limited to the following examples.

[0072] (Examples 1 to 3 and Comparative Examples 1 to 3) Under the conditions shown in Table 1, pants-type disposable diapers of Examples 1 to 3 and Comparative Examples 1 to 3 were produced. Elastic thread was used as the elastic member provided in the waist gathers of each pants-type disposable diaper. Each pants-type disposable diaper was evaluated in the following four ways: evaluation of "stickiness of the waist portion," evaluation of "defectiveness during manufacturing," evaluation of "pulp separation," and evaluation of "separability of the waist portion elastic thread."

[0073] (Recycling process) Of the four evaluations, the evaluation of "pulp separability" and the evaluation of "separability of waist elastic thread" were carried out by recycling the pants-type disposable diapers (large size) of Examples 1 to 3 and Comparative Examples 1 to 3 using a rotary drum device (agitator).

[0074] The rotary drum device (agitator) was configured as follows. Tank diameter: 180cm Tank length: 120cm Rotating drum diameter: 160cm Rotating drum length: 110cm Diameter of the rotating drum holes: 0.7cm Axial direction of the tank and rotating drum: horizontal

[0075] The recycling process involves first placing disposable diapers and chemicals (15,000 g of hydrated lime and 800 g of calcium hypochlorite) into the rotating drum of the rotary drum device, then pouring in 800 L of tap water to store the water. The rotating drum is then rotated at 30 rpm, with the rotation direction switched every 120 seconds. After rotation begins, steam is injected to raise the water temperature to 80°C, and a rotary mixing process is performed. After 0.5 hours, the rotating drum is stopped, the water is drained, and the rotating drum is rotated at 300 rpm for 4 minutes to dehydrate the water. After stopping the rotating drum, 800 L of tap water is poured in to store the water and rinse (15 minutes), after which the water is drained and dehydrated in the same manner as above.

[0076] (Stickiness around the waist) The "stickiness in the waist area" evaluation was a sensory evaluation by five panelists regarding stickiness in the waist area (waist opening) of pants-type disposable diapers. "Stickyness in the waist area" occurs when the hot melt adhesive used in the waist gathering area seeps out from the nonwoven fabric sheet of the outer packaging. When removing a pants-type disposable diaper from a package containing multiple pants-type disposable diapers, the panelists checked the "stickiness in the waist area" to ensure that the pants-type disposable diaper was not joined to other pants-type diapers and to ensure that the front and rear waist areas of the waist opening (front and rear waist areas) were not stuck together when the waist opening of the pants-type disposable diaper was opened. They then rated the pants-type diaper on a three-point scale: "not sticky," "slightly sticky," or "sticky and sticky." If three or more panelists gave the same rating, or if two panelists gave different ratings, the lower rating was used to evaluate the pants-type diaper. 〇: No stickiness △: Slightly sticky ×: Sticky and sticky

[0077] (Manufacturing defects) The evaluation of "defectiveness during manufacturing" is based on the percentage of defective products (defective product rate (%)) detected as defective due to the hot melt adhesive used in the waist gathers being too weak (or too strong) during the manufacturing process inspection of pants-type disposable diapers. In the evaluation of "defectiveness during manufacturing," the defective product rate was calculated and evaluated according to the following criteria. Good: Defective product rate is less than 0.1% △: Defective product rate is between 0.1% and 1% ×: Defective product rate is 1% or more

[0078] (pulp separation) The evaluation of "pulp separability" is based on the content of pulp remaining in the recovered plastic after recycling (pulp content (%)). In the evaluation of "pulp separability," the pulp content was calculated and the calculated pulp content was evaluated according to the following criteria. 〇: Pulp content is less than 20% △: Pulp content is 20% or more but less than 25% ×: Pulp content is 25% or more

[0079] (Separability of elastic waist thread) The evaluation of "separability of waist elastic thread" is based on the number of times the agitator (including the drain pump) was stopped to remove the elastic member (elastic thread) per recycling process when approximately 300 kg of used pants-type disposable diapers (large size) were recycled. For example, if the recycling process was carried out 10 times and the agitator was stopped once to remove the elastic member, the number of times the agitator was stopped to remove the elastic member per recycling process would be 0.1 times (1 / 10 = 0.1 times). The values ​​calculated in this way were evaluated according to the following criteria. 〇: Less than 0.1 stops △: Number of stops: 0.1 or more but less than 1 ×: Stops once or more

[0080] The results are shown in Table 1. In the table, the hot melt adhesive is abbreviated as "HM." The "waist gather fold (g)" column in the table indicates the amount of hot melt adhesive applied to the second application area. The "waist gather (g)" column in the table indicates the amount of hot melt adhesive applied to the first application area. The "total waist HM application amount (g)" column indicates the amount of hot melt adhesive applied to the waist gather area. The "top sheet inner side (g)" column in the table indicates the amount of hot melt adhesive applied to the fourth application area. The "top sheet end stop (g)" column in the table indicates the amount of hot melt adhesive applied to the fifth application area. The "interior pad fixing (g)" column in the table indicates the amount of hot melt adhesive applied to the third application area. The column "Total coating weight of absorbent body (g)" indicates the coating weight D of the hot melt adhesive used to bond the absorbent body and the outer body and the hot melt adhesive used in the top sheet of the absorbent body. The column "Coating weight ratio" indicates the ratio of the coating weight A to the coating weight D, where the coating weight A detected by the above-mentioned method is set to 1.

[0081] [Table 1]

[0082] As can be seen from Table 1, it has been confirmed that the present disclosure can provide pants-type disposable diapers that are excellent for material recycling, with a low rate of defective products caused by hot melt adhesive and low seepage of hot melt adhesive during the manufacturing process, and with fewer problems during recycling caused by pulp separability and elastic members such as rubber thread in the waist gathers. [Explanation of symbols]

[0083] 10: Pants-type disposable diapers 20: Exterior body 28: Waist gather 40: Absorbent body 41: Top sheet 42: Back seat 43: Absorbent

Claims

1. A pants-type disposable diaper that can be washed and separated after use and recycled, an outer casing having a waist gathered portion and constituting the outer shape of the pants-type disposable diaper when worn; an absorbent main body having a liquid-permeable top sheet, a liquid-impermeable back sheet, and an absorbent body disposed between the top sheet and the back sheet, and bonded to the skin side of the outer body; The ratio of a second coating amount of the hot melt adhesive used to bond the absorbent main body and the exterior body and the hot melt adhesive used on the top sheet of the absorbent main body to a first coating amount of the hot melt adhesive used on the waist gathered portion of the exterior body is 0.3 or more and 1.0 or less. A pants-type disposable diaper characterized by the above.

2. the first coating amount is 0.75 g or more and 1.05 g or less, The second coating amount is 0.75 g or more and 0.35 g or less.

2. The pants-type disposable diaper according to claim 1, wherein the diaper is made of a material that is not woven.

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