Absorbent article

Abstract

To provide an absorbent article capable of efficiently collecting a material contained in an absorber.SOLUTION: An absorbent article includes a top sheet, a back sheet, and an absorber. The top sheet and the back sheet are joined via an easily oxidatively degradable adhesive.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to an absorbent article. [Background technology]

[0002] Absorbent products such as disposable diapers, sanitary napkins, and pet sheets are composed of a back sheet, a top sheet, a core wrap, super absorbent polymer (SAP), pulp, etc. Of these, pulp is a natural material, so it has a low environmental impact even when disposed of in landfills, and it can also be reused as a raw material for cardboard. In addition, development of biodegradable SAP is underway. To protect the environment, there is a demand for technology that can efficiently separate the SAP and pulp from other materials in used absorbent products.

[0003] A typical absorbent article has an absorbent body made of SAP and pulp placed between a liquid-permeable top sheet and a liquid-impermeable back sheet, sealed with a hot melt adhesive (Patent Documents 1 and 2). In order to recover the SAP and pulp from such an absorbent article, the adhesive joint must be heated or physically destroyed.

[0004] Patent Document 3 discloses an absorbent article that uses a crosslinked polymer compound having a diacylhydrazine structure as a water-absorbing material. This crosslinked polymer compound is stable in air but quickly decomposes when reacted with an oxidizing agent such as sodium hypochlorite. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2016-96882 [Patent Document 2] Japanese Patent Publication No. 2023-176753 [Patent Document 3] International Publication No. 2021 / 131003 Summary of the Invention [Problem to be solved by the invention]

[0006] An object of the present invention is to provide an absorbent article that can efficiently recover materials contained in the absorbent body. [Means for solving the problem]

[0007] The present inventors have found that the above problems can be solved by bonding the top sheet and back sheet that encase the absorbent body via an adhesive that is easily oxidatively decomposable, and have completed the present invention.

[0008] That is, the present invention includes the following aspects. <1> A top sheet, a back sheet, and an absorbent body, The absorbent article has the top sheet and the back sheet bonded together via an easily oxidatively decomposable adhesive portion. <2> Item 1. The absorbent article according to item 1, further comprising a core wrap. <3> Item 3. The absorbent article according to item 2, wherein the absorbent body and at least one selected from the group consisting of the top sheet, the back sheet, and the core wrap are bonded via an easily oxidatively decomposable adhesive. <4> Item 4. The absorbent article according to Item 2 or 3, wherein the core wraps are bonded to each other or to the backsheet via an easily oxidatively decomposable adhesive. <5> Item 2. The absorbent article according to item 1, wherein the adhesive portion contains an easily oxidatively decomposable substance. <6> Item 2. The absorbent article according to item 1, wherein the adhesive portion comprises a layer containing an easily oxidatively decomposable substance and adhesive layers formed on both sides thereof. <7> Item 7. The absorbent article according to item 5 or 6, wherein the layer containing the easily oxidatively decomposable substance is thermoplastic or thermosetting. <8> The easily oxidatively decomposable substance has a hydrazine structure represented by formula (1), Item 7. The absorbent article according to item 5 or 6. -A I -NH-NH-A II - (1) (In formula (1), A I , A II are carbonyl groups or single bonds, and A I and A II At least one of the groups is a carbonyl group. <9> Item 9. The absorbent article according to item 8, wherein the easily oxidatively decomposable substance is represented by formula (2). [ka] (In formula (2), ·n≧0, k≧0, m≧0, p1≧1, p2≧1, p3≧1. ·R 1 , R 2 , R 3 are each independently a divalent group containing a siloxane structure, or a hydrocarbon group which may have a substituent or a heteroatom. X 1a , X 1b , X 2a , X 2b , X 3a , X 3b , X 4a , X 4b are each independently an oxygen atom, a sulfur atom, a single bond, a hydrocarbon group having 1 to 20 carbon atoms which may have a substituent, or -NB- (B is a hydrogen atom or a hydrocarbon group). A 1 ~A 8 are each independently a carbonyl group or a single bond, and A 1 and A 2 At least one of A is a carbonyl group, 3 and A 4 At least one of A is a carbonyl group, 5 and A 6 At least one of A is a carbonyl group, 7 and A 8 At least one of the groups is a carbonyl group. Q 1 , Q 2 , Q3 are each independently hydrogen or a substituent. Z's are each independently a divalent or higher polyvalent group containing a siloxane structure, or a hydrocarbon group having 1 to 500 carbon atoms and optionally containing a hetero atom. <10> Substances that are easily oxidatively decomposed react with oxidizing agents to form Z, R 1 , R 2 , or R 3 Item 10. The absorbent article according to item 9, which produces a carboxylic acid, alcohol, amine, or thiol comprising: <11> Item 7. The absorbent article according to item 5 or 6, wherein the easily oxidatively decomposable substance generates a water-soluble decomposition product upon reaction with an oxidizing agent. <12> Item 3. The absorbent article according to item 1 or 2, wherein the absorbent body comprises an absorbent resin and / or a naturally derived fiber. <13> The top sheet and the back sheet are bonded together by a rectangular adhesive portion that surrounds the absorbent body and / or the core wrap, Two or more sides of the rectangular adhesive joint are adhesive joints that are easily oxidatively decomposable, At least one long side is an adhesive part that is easily oxidatively decomposed; Item 1 or 2. The absorbent article according to item 1 or 2. <14> Item 3. The absorbent article according to item 2, wherein the absorbent body is sandwiched between two or more core wraps, and the two or more core wraps are bonded together by an easily oxidatively decomposable adhesive portion. <15> Item 3. A method for dismantling absorbent articles, comprising the step of immersing the absorbent article according to item 1 or 2 in a solution containing an oxidizing agent at 0 to 60°C. <16> Item 3. A composition for forming the adhesive portion in the absorbent article according to item 1 or 2. [Effects of the Invention]

[0009] Materials contained in the absorbent body can be efficiently recovered from the absorbent article of the present invention. [Brief explanation of the drawings]

[0010] [Figure 1A] FIG. 2 is a cross-sectional view taken along the line AA′ of the absorbent article according to the first embodiment of the present invention. [Figure 1B] 1 is a top view of an absorbent article according to a first embodiment of the present invention. [Figure 2A] FIG. 5 is a cross-sectional view taken along the line BB' of the absorbent article according to the second embodiment of the present invention [Figure 2B] FIG. 2 is a top view of an absorbent article according to a second embodiment of the present invention. [Figure 3A] FIG. 5 is a cross-sectional view taken along the line CC' of the absorbent article according to the third embodiment of the present invention. [Figure 3B] FIG. 10 is a top view of an absorbent article according to a third embodiment of the present invention. [Figure 4A] FIG. 6 is a cross-sectional view taken along the line DD' of an absorbent article according to a fourth embodiment of the present invention [Figure 4B] FIG. 10 is a top view of an absorbent article according to a fourth embodiment of the present invention. [Figure 5A] FIG. 8 is a cross-sectional view taken along the line EE' of an absorbent article according to a fifth embodiment of the present invention [Figure 5B] FIG. 10 is a top view of an absorbent article according to a fifth embodiment of the present invention. [Figure 6A] FIG. 2 is a cross-sectional view taken along the line FF' of an absorbent article according to a sixth embodiment of the present invention [Figure 6B] FIG. 10 is a top view of an absorbent article according to a sixth embodiment of the present invention. [Figure 7A] FIG. 20 is a cross-sectional view of the absorbent article of the seventh embodiment of the present invention taken along the line GG [Figure 7B] FIG. 10 is a top view of an absorbent article according to a seventh embodiment of the present invention. [Figure 8A] FIG. 10 is a cross-sectional view taken along the line HH′ of the absorbent article according to the eighth embodiment of the [Figure 8B] FIG. 10 is a top view of an absorbent article according to an eighth embodiment of the present invention. [Figure 9A] FIG. 10 is a cross-sectional view taken along II' line of an absorbent article according to a ninth embodiment of the present [Figure 9B] FIG. 10 is a top view of an absorbent article according to a ninth embodiment of the present invention. [Figure 10] FIG. 2 is a cross-sectional view of an example of an adhesive joint. [Figure 11] FIG. 2 is a cross-sectional view of an example of an adhesive joint. [Figure 12] FIG. 2 is a cross-sectional view of an example of an adhesive joint. [Figure 13] FIG. 2 is a cross-sectional view of an example of an adhesive joint. [Figure 14] FIG. 2 is a cross-sectional view of an example of an adhesive joint. [Figure 15] FIG. 2 is a cross-sectional view of an example of an adhesive joint. DETAILED DESCRIPTION OF THE INVENTION

[0011] <<Absorbent articles>> The absorbent article of the present invention comprises a top sheet, a back sheet, and an absorbent body, and is characterized in that the top sheet and the back sheet are bonded together via an oxidatively decomposable adhesive. The absorbent article may further comprise a core wrap. In the absorbent article of the present invention, the top sheet and the back sheet are bonded together via an oxidatively decomposable adhesive, so that the adhesive decomposes when the absorbent article is immersed in a solution containing an oxidizing agent, allowing the absorbent body to be easily recovered. The materials contained in the recovered absorbent body can be reused.

[0012] <Sheet-shaped substrate> The top sheet, back sheet, and core wrap are all sheet-like substrates. The top sheet is a sheet-like substrate that is placed closer to the wearer's skin than the absorbent body, and is preferably liquid-permeable to body fluids such as urine and blood. Examples of the top sheet's shape include woven fabric, nonwoven fabric, and porous film. Examples of materials that constitute the top sheet include polypropylene, polyethylene, polyester, polyamide, cellulose, rayon, and cotton.

[0013] The backsheet is a sheet-like substrate that is placed farther from the wearer's skin than the absorbent body, and is preferably liquid-impermeable to prevent leakage of bodily fluids held by the absorbent article. Examples of the backsheet form include nonwoven fabric and film. Examples of materials for the backsheet include polyethylene, polypropylene, and polyurethane. When using a film as the backsheet, it is preferable to use a moisture-permeable film to prevent stuffiness when worn. Alternatively, a laminated backsheet in which a liquid-permeable sheet is bonded to a liquid-impermeable sheet with an adhesive or the like can also be used.

[0014] The core wrap is a sheet-like substrate that encases the absorbent and holds the absorbent resin and natural fibers contained in the absorbent. Examples of core wrap include woven fabric, nonwoven fabric, porous film, and paper sheet. Materials that can be used to construct the core wrap include polypropylene, polyethylene, polyester, cellulose, rayon, and cotton.

[0015] In addition to the top sheet, back sheet, and core wrap, the absorbent article may also include sheet-like substrates that are generally included in absorbent articles, such as a leak-proof guard sheet, a distribution sheet that is placed under the top sheet to promote the dispersion of body fluids into the absorbent body, a cover sheet that reinforces the back sheet and improves the feel, a deodorizing sheet that absorbs odors, an adhesive sheet for fastening to clothing, etc., and a waist stretch sheet or fastening tape for fastening to the body.

[0016] <Absorbent> Absorbents absorb and retain liquids. Examples of materials that make up absorbents include absorbent resins and fibers. Examples of absorbent resins include synthetic resins such as poly(meth)acrylic resins and polyacrylamide resins, as well as naturally occurring absorbent resins. Examples of fibers include naturally occurring fibers. In particular, when the absorbent resin is a biodegradable material, such as polyaspartic acid, cellulose, chitin, chitosan, starch, or a derivative thereof, even when used in combination with naturally occurring fibers, the two can be disposed of in landfills or used as fertilizer raw materials without separation. Some of these biodegradable materials are easily decomposed by acids or alkalis. When absorbents containing such materials are used, naturally occurring fibers can be recovered in high purity. Furthermore, when the absorbent resin is made of a material that can be decomposed by an oxidizing agent, such as polyacrylic acid with a hydrazine structure, the absorbent resin can be easily decomposed, allowing naturally occurring fibers to be recovered in high purity.

[0017] Examples of naturally occurring fibers that can be used include cellulose fibers such as mechanical pulp, chemical pulp, semi-chemical pulp, and dissolving pulp obtained from wood, regenerated fibers such as rayon and acetate, and cotton fibers. The absorbent body is preferably one in which an absorbent resin is held in these naturally occurring fibers.

[0018] <Adhesive part> In the absorbent article, the top sheet and the back sheet are bonded via an oxidatively degradable adhesive, which fixes the absorbent body within the absorbent article. As long as the oxidatively degradable adhesive is present between the top sheet and the back sheet, it can efficiently detach the absorbent body from the absorbent article upon contact with a solution containing an oxidizing agent, so the position of the oxidatively degradable adhesive within the absorbent article and the combination of the adhesive bodies are not particularly limited.

[0019] In the absorbent article, the core wraps may be bonded to each other or to the back sheet via an oxidatively decomposable adhesive. The absorbent body may be bonded to at least one selected from the group consisting of the top sheet, the back sheet, and the core wrap via an oxidatively decomposable adhesive. In these embodiments, the absorbent body can be reliably fixed within the absorbent article, and can be efficiently recovered by reaction with an oxidizing agent.

[0020] When at least a portion of the core wrap is bonded to the core wrap via an easily oxidatively decomposable adhesive, the absorbent body may be sandwiched between two or more core wraps and then the core wraps may be bonded together, or the absorbent body may be wrapped inside a folded core wrap and then the ends of the folded core wrap may be bonded. The core wrap may be formed into a cylindrical shape and then the absorbent body may be enclosed inside, and the ends may be bonded using an easily oxidatively decomposable adhesive. When the absorbent body is wrapped in the core wrap, all four sides may be closed, or one or two sides may be open. Specific examples of absorbent articles will be described based on the following embodiments 1 to 9, but are not limited to these.

[0021] Embodiment 1 is shown in Figures 1A and 1B. Embodiment 1 is an example without a core wrap. Figure 1A is a cross-sectional view taken along the line A-A' in Figure 1B. An absorbent body 15 of an absorbent article 10 is sandwiched between a back sheet 13 and a top sheet 11. The top sheet 11 and the back sheet 13 are bonded together around the periphery of the absorbent body by adhesive sections 14, so that the absorbent body 15 is held inside. It is preferable that the adhesive sections 14 are easily oxidatively decomposable on at least two of the four sides.

[0022] Embodiment 2 is shown in FIGS. 2A and 2B, and Embodiment 3 is shown in FIGS. 3A and 3B. FIG. 2A is a B-B' cross-sectional view of FIG. 2B. FIG. 3A is a C-C' cross-sectional view of FIG. 3B. In Embodiments 2 and 3, the absorbent body 15 is wrapped in and held within the folded core wrap 12. In Embodiment 2, the adhesive surfaces of the core wrap 12 are on the side and backsheet 13 sides. In Embodiment 3, the adhesive surface of the core wrap 12 is on the backsheet 13 side. In Embodiments 2 and 3, the ends of the core wrap 12 are bonded via an oxidatively degradable adhesive 14 between the core wraps 12. When the absorbent body 15 is sealed by the core wrap 12 as in Embodiment 2, it is preferable that two approximately parallel sides of the core wrap 12 are bonded via an oxidatively degradable adhesive 14. When the absorbent body 15 is not sealed by the core wrap 12 as in Embodiment 3, the adhesive 14 does not have to be oxidatively degradable. In embodiments 2 and 3, the top sheet 11 and the back sheet 13 preferably have an oxidatively decomposable adhesive at at least two of the four adhesive edges 14, as in embodiment 1. The core wrap 12 and the back sheet 13 may be bonded together by an oxidatively decomposable adhesive, or may be bonded together by an adhesive that is not oxidatively decomposable, or may not be bonded at all.

[0023] Embodiment 4 is shown in Figures 4A and 4B, and embodiment 5 is shown in Figures 5A and 5B. Figure 4A is a cross-sectional view taken along the line D-D' in Figure 4B. Figure 5A is a cross-sectional view taken along the line E-E' in Figure 5B. Embodiments 4 and 5 are examples in which an absorbent body 15 is held by a single core wrap 12. In embodiment 4, the absorbent body 15 is sealed by adhesive parts 14 in three directions, and in embodiment 5, one side of the core wrap 12 is adhesively attached and two sides are free.

[0024] Of the adhesive joints 14 between the core wraps 12 in embodiment 4, it is preferable that the adhesive joints 14 on two or more sides are easily oxidatively decomposable. In embodiment 5, the adhesive joints between the core wraps 12 do not have to be easily oxidatively decomposable. As in embodiments 1 to 3, it is preferable that the adhesive joints 14 on at least two sides of the adhesive joints 14 on the four sides between the top sheet 11 and the back sheet 13 are easily oxidatively decomposable. The core wrap 12 and the back sheet 13 may be bonded together by an adhesive joint that is easily oxidatively decomposable, but they may also be bonded together by an adhesive joint that is not easily oxidatively decomposable, or they may not be bonded at all.

[0025] Embodiment 6 is shown in Figures 6A and 6B, and Embodiment 7 is shown in Figures 7A and 7B. Figure 6A is a cross-sectional view taken along the line F-F' of Figure 6B. Figure 7A is a cross-sectional view taken along the line G-G' of Figure 7B. Embodiments 6 and 7 are examples in which an absorbent body 15 is held in a single cylindrically formed core wrap 12. In Embodiment 6, the cylindrical opening is sealed by a bonded joint 14 between the core wraps 12. In Embodiment 7, there is no bonded joint between the core wraps 12, leaving the core wraps 12 open. In Embodiment 6, the bonded joint 14 between the core wraps 12 is preferably an oxidatively degradable joint. As in Embodiments 1 to 5, the top sheet 11 and the back sheet 13 preferably have an oxidatively degradable joint on at least two of the four bonded joints 14. The core wrap 12 and the back sheet 13 may be bonded by a bonded joint that is easily oxidatively degradable, or may be bonded by a bonded joint that is not easily oxidatively degradable, or may not be bonded at all.

[0026] Embodiment 8 is shown in Figures 8A and 8B, and Embodiment 9 is shown in Figures 9A and 9B. Figure 8A is a cross-sectional view taken along the line H-H' in Figure 8B. Figure 9A is a cross-sectional view taken along the line I-I' in Figure 9B. In Embodiments 8 and 9, an absorbent body 15 is sandwiched between two core wraps 12. In Embodiment 8, the absorbent body 15 is sealed by the bonded joints 14 between the core wraps 12, while in Embodiment 9, two sides of the core wrap 12 are open. Of the bonded joints 14 between the core wraps 12 in Embodiment 8, two or more sides are preferably easily oxidatively degradable. In Embodiment 9, the bonded joints 14 between the core wraps 12 do not have to be easily oxidatively degradable. As in Embodiments 1 to 7, it is preferable that at least two of the four bonded joints 14 of the top sheet 11 and the back sheet 13 are easily oxidatively degradable. The core wrap 12 and the back sheet 13 may be bonded together by an adhesive that is easily oxidatively decomposable, or may be bonded together by an adhesive that is not easily oxidatively decomposable, or may not be bonded at all.

[0027] In an absorbent article, when a top sheet and a back sheet are overlapped, for example as shown in Figure 1B, the top sheet and the back sheet are bonded together by a rectangular adhesive portion that surrounds the absorbent body and / or core wrap, and it is preferable that two or more sides of the rectangular adhesive portion are easily oxidatively degradable adhesive portions. When the rectangle is rectangular, it is preferable that at least one long side is easily oxidatively degradable adhesive portion. In this case, the absorbent body can be efficiently recovered by reaction with an oxidizing agent while being securely held during use of the absorbent article.

[0028] The structure of the oxidatively decomposable adhesive joint is not particularly limited as long as at least a part of the adhesive joint is oxidatively decomposable and can be decomposed when immersed in a solution containing an oxidizing agent. The adhesive joint can be made oxidatively decomposable by including an oxidatively decomposable substance in at least a part of the adhesive joint.

[0029] In the present invention, the "easily oxidatively decomposable" of an oxidatively decomposable substance refers to the property of decomposing an adhesive joint between sheet-like substrates or between a sheet-like substrate and an absorbent body when the adhesive joint is immersed in a solution containing an oxidizing agent. Examples of combinations of sheet-like substrates that can be bonded by an oxidatively decomposable adhesive joint include a top sheet and a back sheet, a core wrap and a back sheet, and a core wrap and a core wrap. Examples of combinations of a sheet-like substrate and an absorbent body that can be bonded by an oxidatively decomposable adhesive joint include a back sheet and an absorbent body, and a core wrap and an absorbent body. The oxidatively decomposable adhesive joint may be a thermoplastic resin or a thermosetting resin. Specific examples of the configuration of an oxidatively decomposable adhesive joint include (1) an adhesive joint consisting only of an oxidatively decomposable layer, and (2) an adhesive joint consisting of an oxidatively decomposable layer and an adhesive layer laminated together.

[0030] In an adhesive joint consisting only of a (1) easily oxidatively decomposable layer, the easily oxidatively decomposable layer may contain only an easily oxidatively decomposable substance, or may be a layer consisting of a mixture of an easily oxidatively decomposable substance and an adhesive. Examples of an adhesive joint consisting only of a (1) easily oxidatively decomposable layer are shown in Figures 10 to 11. An adhesive joint consisting only of a (1) easily oxidatively decomposable layer may be made of a resin composition containing an easily oxidatively decomposable substance and having adhesive properties. Furthermore, an adhesive joint consisting only of a (1) easily oxidatively decomposable layer may be made of an easily oxidatively decomposable substance having adhesive properties.

[0031] (2) An adhesive joint formed by laminating an oxidatively decomposable layer and an adhesive layer is formed, for example, when a resin composition without adhesive properties is used. When a laminate consisting of an oxidatively decomposable layer (a) and adhesive layers (b) formed on both sides of the layer is present between two adherends, sufficient adhesion can be achieved across the adhesive joint as a whole, even when the oxidatively decomposable layer is made of a resin composition without adhesive properties. Furthermore, when an absorbent article is immersed in a solution containing an oxidizing agent, the oxidatively decomposable layer is decomposed, destroying the adhesive joint and releasing the adhesion between the adherends. Adhesive compositions conventionally used in the manufacture of absorbent articles can be used as adhesive compositions for forming the adhesive layers (b) formed on both sides of the oxidatively decomposable layer. Specific examples include compositions containing adhesives, plasticizers, waxes, surfactants, tackifiers, stabilizers, and the like, which are described below as optional components of resin compositions. (2) Examples of adhesive joints formed by laminating an oxidatively decomposable layer and an adhesive layer are shown in Figures 12 to 15.

[0032] The adhesiveness of a resin composition can be evaluated by placing the resin composition between a top sheet and a back sheet, thermocompressing them, and then peeling the top sheet and back sheet at 180 degrees, and visually observing the surface condition of the peeled surface. If the peeling between the top sheet and back sheet is at the interface between the substrate and the resin composition layer, the area that can be used may be limited, so peeling due to cohesive failure of the adhesive joint is preferred, and peeling due to material failure of the substrate is more preferred. It can also be evaluated by a T-peel test in accordance with JIS K6845. For example, if the peel strength at a tensile speed of 100 mm / min is 0.1 N / 25 mm or more, it is unlikely to cause any problems in practical use, and if it is 0.2 N / 25 mm or more, it can be used for a wider range of applications, and if it is 0.3 N / 25 mm or more, it is even more preferable.

[0033] Furthermore, the hardness of the adhesive joint is not particularly limited, but it is preferable that it has flexibility and stretchability. When used as an absorbent article intended for clothing, if the adhesive joint is too hard, cracks may occur in the adhesive joint due to body movement, which may cause problems such as leakage of liquid or part of the absorbent body during use. The durometer hardness measured in accordance with JIS K7215 is preferably, for example, 50 or less in D hardness, and the tensile modulus measured in accordance with JIS K7127 and JIS K7161-1 is preferably, for example, 0.01 to 5.5 MPa.

[0034] Specific examples of easily oxidatively decomposable adhesive parts will be described with reference to the drawings. Figure 10 shows an embodiment in which a top sheet or core wrap 101 and a back sheet or core wrap 102 are adhered by an easily oxidatively decomposable layer 103.

[0035] FIG. 11 shows an embodiment in which a topsheet or core wrap 101 and a backsheet or core wrap 102 are bonded together by an adhesive-containing layer 105 that is easily oxidatively degradable.

[0036] 12 shows an embodiment in which a top sheet or core wrap 101 and a back sheet or core wrap 102 are bonded together by an easily oxidatively degradable layer 103 and an adhesive layer 104. Even if the easily oxidatively degradable layer only adheres to a specific sheet-like substrate, the provision of adhesive layer 104 makes it possible to bond a back sheet or core wrap 102 made of a wide variety of materials.

[0037] 13 shows an embodiment in which a top sheet or core wrap 101 and a back sheet or core wrap 102 are bonded together by an oxidatively degradable layer 103 and an adhesive layer 104. Even if the oxidatively degradable layer only adheres to a specific sheet-like substrate, the provision of adhesive layer 104 makes it possible to bond top sheets or core wraps 101 made of a wide variety of materials.

[0038] 14 shows an embodiment in which a top sheet or core wrap 101 and a back sheet or core wrap 102 are bonded together by two oxidatively degradable layers 103 and an adhesive layer 104. Even if the oxidatively degradable layer only adheres to a specific sheet-like substrate, the provision of adhesive layer 104 makes it possible to bond a top sheet or core wrap 101 made of a wide variety of materials to a back sheet or core wrap 102 made of a wide variety of materials.

[0039] FIG. 15 shows an embodiment in which a top sheet or core wrap 101 and a back sheet or core wrap 102 are bonded together by an easily oxidatively degradable layer 103 and two adhesive layers 104 .

[0040] 10 to 15, one to three layers are formed between the top sheet or core wrap 101 and the back sheet or core wrap 102, but the number of layers is not particularly limited. Furthermore, the two easily oxidatively decomposable layers 103 in FIG. 14 may be formed of the same material or different materials. Similarly, the two adhesive layers 104 in FIG. 15 may be formed of the same material or different materials.

[0041] <Resin composition> The resin composition is not particularly limited in composition as long as it can form an easily oxidatively decomposable layer by heating or drying. Examples include (i) a resin composition that contains an easily oxidatively decomposable substance that is easily decomposable by an oxidizing agent, and (ii) a resin composition that generates an easily oxidatively decomposable substance by heating or drying during adhesive joint formation.

[0042] (i) The structure of the easily oxidatively decomposable substance blended into the resin composition containing the easily oxidatively decomposable substance is not particularly limited as long as it is decomposed by reaction with an oxidizing agent. For example, a compound having a hydrazine structure or an azo structure that is easily decomposed by reaction with an oxidizing agent can be mentioned. An easily oxidatively decomposable substance having a hydrazine structure is preferred in terms of being able to form a stable and strong adhesive joint. Note that the hydrazine structure can also be converted to an azo structure by a controlled oxidation reaction.

[0043] The content of the easily oxidatively decomposable substance in the resin composition is preferably 1 to 100% by weight, more preferably 20 to 100% by weight, and even more preferably 50 to 100% by weight, based on the total solid content. If it is less than 1% by weight, dismantling properties tend to decrease.

[0044] (ii) Examples of resin compositions that generate substances that are easily oxidatively decomposable by heating or drying during adhesive joint formation include resin compositions that contain, as components for generating oxidatively decomposable substances, a compound having a diazonio group and an aromatic compound having an electron-donating group; resin compositions that contain a compound having a hydrazino group and a compound having an isocyanate group, an active ester group, or an acid anhydride group; and resin compositions that contain a compound having a hydrazide group, semicarbazide group, or carbazate group and a compound having an epoxy group, oxetane group, acrylate group, methacrylate group, isocyanate group, active ester group, acid anhydride group, or carbonate group.

[0045] <Easily oxidized and decomposable substances> The substance easily decomposable by oxidation preferably has a hydrazine structure represented by formula (1). -A I -NH-NH-A II - (1) In formula (1), A I , A II are carbonyl groups or single bonds, and A I and A II At least one of A is a carbonyl group. I and A II When one of the groups is a carbonyl group, it has the advantage of being easily decomposed with an oxidizing agent. I and A II When both of the groups are carbonyl groups, there is an advantage that the decomposition products are easily dissolved in a solution.

[0046] The substance easily oxidatively decomposable having a hydrazine structure is preferably represented by formula (2). [ka] In formula (2), ·n≧0, k≧0, m≧0, p1≧1, p2≧1, p3≧1. ·R 1 , R 2 , R 3 are each independently a divalent group containing a siloxane structure, or a hydrocarbon group which may have a substituent or a heteroatom. X 1a , X 1b , X 2a , X 2b , X 3a , X 3b , X 4a , X 4b are each independently an oxygen atom, a sulfur atom, a single bond, a hydrocarbon group having 1 to 20 carbon atoms which may have a substituent, or -NB- (B is a hydrogen atom or a hydrocarbon group). A 1 ~A 8 are each independently a carbonyl group or a single bond, and A 1 and A 2 At least one of A is a carbonyl group, 3 and A 4 At least one of A is a carbonyl group, 5 and A 6 At least one of A is a carbonyl group, 7 and A 8 At least one of the groups is a carbonyl group. Q 1 , Q 2 , Q 3 are each independently hydrogen or a substituent. ·Z's are each independently a divalent or higher polyvalent group containing a siloxane structure, or a hydrocarbon group having 1 to 500 carbon atoms and optionally containing a hetero atom.

[0047] The oxidatively decomposable substance having a hydrazine structure preferably has a weight-average molecular weight of 300 to 300,000, more preferably 3,000 to 50,000. The oxidatively decomposable substance having a hydrazine structure is preferably liquid at 20 to 120°C, more preferably liquid at 30 to 60°C, so as to have excellent miscibility with other components when preparing a resin composition.

[0048] In the easily oxidatively decomposable substance having a hydrazine structure, the portion consisting of "NHNH" of the hydrazine structure represented by formula (1) is preferably 10% by weight or less, more preferably 9.3% by weight or less, and even more preferably 3.1% by weight or less in the molecule. Within these ranges, a resin composition containing an easily oxidatively decomposable substance having a hydrazine structure exhibits good heat-sealing properties.

[0049] <n, m, and k in formula (2)> In formula (2), m and n are 0 or more, but each independently is preferably 1 to 50, more preferably 1 to 5. When m and n are 1 or more, the compound has two or more hydrazine structures (-A-NH-NH-A-), thereby improving decomposition properties. There are no particular limitations on the upper limits of m and n, but they can be set to 50 or less.

[0050] In formula (2), k is 0 or more, preferably 1 or more, and more preferably 2 or more. When k is 1 or more, the oxidatively decomposable substance can form a three-dimensional network structure by reacting with itself or with other compounds. The upper limit of k is not particularly limited, but can be 200 or less.

[0051] <R in formula (2) 1 , R 2 , and R 3 > R 1 , R 2 , and R 3 are each independently a divalent group containing a siloxane structure, or a hydrocarbon group which may have a substituent or a heteroatom.

[0052] The divalent group containing a siloxane structure contains an -Si-O- bond as a main skeleton. The main skeleton may be a linear structure, a branched structure, or a cyclic structure. The number of silicon atoms in the divalent group containing a siloxane structure is preferably 2 to 400, more preferably 4 to 200, and even more preferably 8 to 150.

[0053] In the siloxane structure, the hydrogen atoms bonded to the silicon atoms may be substituted. Specific examples of the substituent include alkyl groups, alkoxy groups, phenoxy groups, halogen atoms, amino groups, sulfo groups, cyano groups, and nitro groups.

[0054] Specific examples of divalent groups containing a siloxane structure include dimethyl silicone, diethyl silicone, ethyl methyl silicone, polymethyl silsesquioxane, and modified silicones obtained by modifying the hydrocarbon groups at the ends and / or side chains of these groups to contain heteroatoms such as N, S, O, and P.

[0055] R 1 , R 2 , and R 3 When is a hydrocarbon group, in order to achieve a good decomposition rate and solvent solubility, the number of carbon atoms therein is preferably 1 to 500, more preferably 1 to 100, and even more preferably 1 to 10. The hydrocarbon group may be a saturated or unsaturated hydrocarbon group, and may have any of a linear structure, a branched structure, and a cyclic structure.

[0056] The hydrocarbon group may have a substituent, specific examples of which include an alkoxy group, a phenoxy group, a halogen atom, an amino group, a sulfo group, a cyano group, and a nitro group.

[0057] The hydrocarbon group may contain heteroatoms. When heteroatoms are contained, the number thereof is preferably 1 to 300. The heteroatoms may be present in the main chain of the hydrocarbon group or in the side chain. Examples of heteroatoms include N, S, O, and P. Examples of structures containing heteroatoms contained in the hydrocarbon group include: [ka] The hydrocarbon group may not contain a heteroatom.

[0058] Specific examples of hydrocarbon groups include linear hydrocarbons such as methylene, ethylene, propylene, butylene, pentylene, hexylene, heptylene, octylene, nonylene, ether, urethane, urea, ester, thioether, carbonate, and amide; branched hydrocarbons such as isopropylene, isobutylene, 2,2-dimethylpropylene, and 2-ethyl-2-methylpropylene; cyclic hydrocarbons such as cyclohexylene, cyclopentylene, norbornenylene, phenylene, and naphthylene; PEG chains; and trivalent or tetravalent groups formed from these groups. The hydrogen atoms of these hydrocarbon groups may be substituted with the aforementioned substituents.

[0059] <Z in formula (2)> In formula (2), a plurality of Z's are each independently a divalent or higher polyvalent group containing a siloxane structure, or a hydrocarbon group having 1 to 500 carbon atoms and optionally containing a hetero atom.

[0060] When Z is a divalent or higher valent group containing a siloxane structure, the group containing a siloxane structure contains an -Si-O- bond as a main skeleton. The main skeleton may be a linear structure, a branched structure, or a cyclic structure. The number of silicon atoms in the group containing a siloxane structure is preferably 2 to 400, more preferably 4 to 200, and even more preferably 8 to 150.

[0061] In the siloxane structure, the hydrogen atoms bonded to the silicon atoms may be substituted. Specific examples of the substituent include alkyl groups, alkoxy groups, phenoxy groups, halogen atoms, amino groups, sulfo groups, cyano groups, and nitro groups.

[0062] Specific examples of groups containing a siloxane structure include dimethyl silicone, diethyl silicone, ethylmethyl silicone, polymethylsilsesquioxane, and modified silicones obtained by modifying the hydrocarbon groups at the ends and / or side chains of these groups to contain heteroatoms such as N, S, O, and P.

[0063] When Z is a hydrocarbon group having 1 to 500 carbon atoms which may have a heteroatom, the number of carbon atoms is more preferably 1 to 200, and even more preferably 2 to 30, from the viewpoints of decomposition rate and crosslink density. The hydrocarbon group has a saturated or unsaturated hydrocarbon group as the main skeleton, and may have either a branched or linear structure. Furthermore, the skeleton of the hydrocarbon group may have a cyclic structure.

[0064] The hydrocarbon group may contain heteroatoms such as N, S, and O. The heteroatoms may be present in the main chain or side chain of the hydrocarbon group. Examples of structures containing heteroatoms include ether bonds, urethane bonds, urea bonds, -NH- optionally substituted with a hydrogen atom, silicone bonds, ester bonds, thioether bonds, and carbonate bonds. Methylene groups other than those at the terminals in the hydrocarbon group may be replaced with 1 to 4 heteroatoms selected from N, S, and O, or arylene or heteroarylene groups. Hydrogen atoms in the hydrocarbon group may be substituted with hydroxy, cyano, amino, nitro, halogen, or phenyl. However, it is preferable that the structure of Z does not contain a disulfide bond. This is because disulfide bonds can generate sulfonic acids when exposed to an oxidizing agent.

[0065] The hydrocarbon group may have a substituent, specific examples of which include an alkoxy group, a phenoxy group, a halogen atom, an amino group, a sulfo group, a cyano group, and a nitro group.

[0066] The hydrocarbon group may have a reactive functional group, such as a hydroxyl group, an amino group, a hydrazide group, a thiol group, an isoprenyl group, a crotonamide group, a crotonate group, a carboxylic acid, an acid anhydride group, a vinyl group, an allyl group, an acrylate group, a methacrylate group, an acrylamide group, a methacrylamide group, a hydroxysilyl group, an epoxy group, an oxetane group, an oxazoline group, an isocyanate group, a carbodiimide group, a methylol group, a silanol group, or an alkoxysilyl group.

[0067] Specific examples of the hydrocarbon group include linear hydrocarbons such as methylene, ethylene, propylene, butylene, pentylene, hexylene, heptylene, octylene, nonylene, ether, urethane, urea, ester, thioether, carbonate, amide, etc., branched-chain hydrocarbons such as isopropylene, isobutylene, 2,2-dimethylpropylene, 2-ethyl-2-methylpropylene, etc., cyclic hydrocarbons such as cyclohexylene, cyclopentylene, norbornenylene, phenylene, naphthylene, etc., PEG chains, etc., and those in which these groups become trivalent or tetravalent groups. The hydrogen atoms of these hydrocarbon groups may be substituted with the substituents described above.

[0068] <Molecular weight of R, Z> In formula (2), R 1 , R 2 , and at least one selected from the group consisting of R 3 , and / or it is preferable that the molecular weight of at least one Z is 200 or more. By adjusting the molecular weights of R and Z in this way, the solubility of the easily oxidizable and decomposable substance in the solvent can be improved. Further, the precipitation of the easily oxidizable and decomposable substance is suppressed, and an adhesive part with uniform composition and physical properties can be obtained.

[0069] The molecular weight is more preferably 300 or more, further preferably 700 or more, and even more preferably 900 or more. The upper limit of the molecular weight is not particularly limited, but generally it is 10000 or less. When the molecular weight is within these ranges, the solubility of the easily decomposable crosslinking agent in the solvent can be improved. For the method of determining the molecular weights of R 1 , R 2 , R 3 , Z, for example, there are methods such as determining by GPC (gel permeation chromatography) from the decomposition products generated by contacting the easily decomposable crosslinking agent with an oxidizing agent, and methods determined by NMR structure determination. When the molecular weight is determined by GPC (gel permeation chromatography), it is determined as the weight average molecular weight (Mw).

[0070] In formula (2), it is preferable that n≧1 and k≧1. In this case, the oxidatively decomposable substance is branched, allowing for three-dimensional crosslinking. Furthermore, in formula (2), it is preferable that n≧1 and k≧1, and the molecular weight of Z is 200 or more, more preferably 300 or more, and even more preferably 700 or more. In this case, the oxidatively decomposable substance has Z as the main skeleton and is branched with two or more hydrazine structures (-A-NH-NH-A-) in the side chains, and can form a three-dimensional network structure by reaction with itself or with other compounds.

[0071] <X in formula (2) 1a , X 1b , X 2a , X 2b , X 3a , X 3b , X 4a , X 4b > In formula (2), X 1a , X 1b , X 2a , X 2b , X 3a , X 3b , X 4a , X 4b are each independently an oxygen atom, a sulfur atom, a single bond, a hydrocarbon group having 1 to 20 carbon atoms which may have a substituent, or -NB- (B is a hydrogen atom or a hydrocarbon group). 1a , X 1b , X 2a , X 2b , X 3a , X 3b , X 4a , X 4b These are collectively referred to as X.

[0072] When X is a hydrocarbon group, it has 1 to 20 carbon atoms, preferably 1 to 10 carbon atoms, and more preferably 1 to 6 carbon atoms, from the viewpoint of ease of handling and ease of carrying out a crosslinking reaction.

[0073] The hydrocarbon group has a saturated or unsaturated hydrocarbon group as a main skeleton. The hydrocarbon group may have either a branched or linear structure. The hydrocarbon group skeleton may also have a cyclic structure.

[0074] The hydrocarbon group may have heteroatoms such as N, S, and O in the molecular chain. Methylene groups other than those at the terminals in the hydrocarbon group may be replaced with 1 to 4 heteroatoms selected from N, S, and O, or arylene or heteroarylene groups. Hydrogen atoms in the hydrocarbon group may be substituted with cyano, nitro, halogen, or phenyl.

[0075] Specific examples of the hydrocarbon group include linear hydrocarbons such as methylene, ethylene, propylene, butylene, pentylene, hexylene, heptylene, octylene, and nonylene, branched hydrocarbons such as 2,2-dimethylpropylene and 2-ethyl-2-methylpropylene, and cyclic hydrocarbons such as 1,4-cyclohexylene, cyclopentylene, norbornenylene, phenylene, and naphthylene. Of these, methylene and phenylene are preferred.

[0076] When X is -NB-, B is a hydrogen atom or a hydrocarbon group. When B is a hydrocarbon group, from the viewpoint of decomposition rate, the number of carbon atoms therein is preferably 1 to 10, more preferably 1 to 5. B, which is a hydrocarbon group, has a saturated or unsaturated hydrocarbon group as the main skeleton, and may have either a branched or linear structure. In addition, the skeleton formed by the hydrocarbon group may have a cyclic structure.

[0077] Furthermore, the hydrocarbon group B may have heteroatoms such as N, S, and O in the molecular chain. Methylene groups other than those at the terminals in the hydrocarbon group may be replaced with 1 to 4 heteroatoms selected from N, S, and O, or arylene or heteroarylene groups. Hydrogen atoms in the hydrocarbon group may be substituted with cyano, nitro, halogen, or phenyl.

[0078] Specific examples of B, which is a hydrocarbon group, include linear hydrocarbons such as methylene, ethylene, propylene, butylene, pentylene, hexylene, heptylene, octylene, and nonylene, branched hydrocarbons such as 2,2-dimethylpropylene and 2-ethyl-2-methylpropylene, cyclic hydrocarbons such as 1,4-cyclohexylene, cyclopentylene, norbornenylene, phenylene, and naphthylene, PEG chains, and trivalent or tetravalent groups of these groups. Of these, linear hydrocarbons are preferred.

[0079] <A in formula (2) 1 ~A 8 > In formula (2), A 1 ~A 8 is a carbonyl group or a single bond, and A 1 and A 2 At least one of A is a carbonyl group, 3 and A 4 At least one of A is a carbonyl group, 5 and A 6 At least one of A is a carbonyl group, 7 and A 8 At least one of the two A's on either side of -NH-NH- is a carbonyl group. When one of the two A's is a carbonyl group, the decomposition efficiency by an oxidizing agent tends to improve. When both are carbonyl groups, the decomposition product tends to dissolve more easily in a solution containing an oxidizing agent.

[0080] <Q in Equation (2) 1 , Q 2 , and Q 3 > In equation (2), Q 1 , Q 2 , Q 3 are each independently hydrogen or a substituent. Examples of the substituent include a hydrocarbon group which may have a heteroatom such as N, S, O, or P, and a halogen. The substituent may be reactive or non-reactive.

[0081] The number of carbon atoms in the hydrocarbon group which may have a heteroatom is preferably 1 to 700, more preferably 3 to 300, and even more preferably 5 to 100. The hydrocarbon group has a saturated or unsaturated hydrocarbon group as the main skeleton, and may have a linear structure, a branched structure, or a cyclic structure.

[0082] Specific examples of the hydrocarbon group include linear hydrocarbons such as methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, and amide groups; branched hydrocarbons such as isopropyl and isobutyl groups; and cyclic hydrocarbons such as phenyl, cyclohexyl, cyclopentyl, and naphthyl groups.

[0083] The hydrocarbon group may have a reactive functional group such as a hydroxyl group, an amino group, a thiol group, a hydrazide group, a carboxylic acid, an acid anhydride group, a vinyl group, an allyl group, an acrylate group, a methacrylate group, a crotonate group, an isoprenyl group, an acrylamide group, a methacrylamide group, a crotonamide group, an epoxy group, an oxetane group, an oxazoline group, an isocyanate group, a carbodiimide group, a methylol group, a silanol group, a hydroxysilyl group, or an alkoxysilyl group.

[0084] Halogens include fluorine (F), chlorine (Cl), bromine (Br), and iodine (I).

[0085] p1, p2, and p3 are each Q contained in easily oxidatively decomposable substances 1 , Q 2 , Q 3 p1, p2, and p3 each represent a number of 1 or more, and each independently represents a number of 1 to 4, more preferably 1 or 2. Q 1 , Q 2 , Q 3 When p1 is a reactive functional group and p1, p2, and p3 are 2 or more, three-dimensional crosslinking becomes easy, and the strength and reliability of the adhesive joint are improved. When p1≧2, p2≧2, or p3≧2, and there are multiple Q 1 Comrade, Q 2 Allies or Q 3When the reactive functional groups are different from each other, various adhesive formation processes can be selected. Furthermore, when only specific reactive functional groups are crosslinked, the reactive functional groups not used in the crosslinking reaction can contribute to improved adhesion or solubility. When p1 = 1, p2 = 1, or p3 = 1, the decomposition rate is likely to be improved.

[0086] <Method for synthesizing substances that are easily oxidatively decomposed and have a hydrazine structure> The method for synthesizing the easily oxidatively decomposable substance to be blended into the resin composition containing the aforementioned (i) easily oxidatively decomposable substance is not particularly limited, and for example, a resin in which carbonyl groups are present on both sides of -NH-NH- can be obtained by reacting a hydrazide compound, semicarbazide compound, or carbazate compound with a carbonate compound, an isocyanate compound, an acid anhydride, an acid halide, or a cyclic ester compound; a reaction between hydrazine and a carboxylic acid ester; a reaction between hydrazine and a carbonate compound; or a reaction between hydrazine and an isocyanate compound.

[0087] Furthermore, for example, a resin in which a carbonyl group is present on one side of -NH-NH- can be obtained by reacting a hydrazide compound, semicarbazide compound, or carbazate compound with a compound having an unsaturated double bond such as an acrylate or methacrylate, an epoxy compound, an oxetane compound, or cyanuric acid chloride; or by reacting a hydrocarbon having a hydrazino group with a carbonate compound, an isocyanate compound, an acid anhydride, an acid halide, or a cyclic ester compound.

[0088] Examples of hydrazide compounds used in the synthesis method include lactic acid hydrazide, methacrylic acid hydrazide, sebacic acid dihydrazide, adipic acid dihydrazide, phthalic acid dihydrazide, salicylic acid dihydrazide, and trimellitic acid trihydrazide. Examples of carbonate compounds include allyl N-succinimidyl carbonate and C,C'-(oxydi-2,1-ethanediyl)bisN-succinimidyl carbonate. Examples of isocyanate compounds include 2-isocyanatoethyl methacrylate, hexamethylene diisocyanate, toluene diisocyanate, and polymethylene polyphenyl polyisocyanate. Examples of semicarbazide compounds include N-allylhydrazinecarboxamide, N,N'-1,6-hexanediylbis[hydrazinecarboxamide], 4,4'-isophoronebis(semicarbazide), and 4,4'-(1,3-phenylenebismethylene)bis(semicarbazide). Examples of carbazate compounds include allylcarbazate and C,C'-(oxydi-2,1-ethanediyl)biscarbazate. Examples of acid anhydrides include methacrylic anhydride, succinic anhydride, and pyromellitic dianhydride. Examples of acid halides include acrylic acid chloride, sebacic acid dichloride, adipic acid dichloride, phthalic acid dichloride, salicylic acid dichloride, and trimesic acid trichloride. Examples of cyclic ester compounds include propiolactone, butyrolactone, valerolactone, etc. Examples of carboxylic acid esters include ethyl lactate, methylparaben, monomethyl succinate, diethyl adipate, trimethyl trimellitate, etc.

[0089] The easily oxidatively decomposable substance having a hydrazine structure represented by formula (1) and the easily oxidatively decomposable substance having a hydrazine structure represented by formula (2) may or may not have a reactive functional group. If they have a reactive functional group, they can be used as a crosslinked resin component in a thermosetting resin composition containing a crosslinking agent or catalyst to form an adhesive joint with excellent heat resistance and storage stability. If they do not have a reactive functional group, they can be used as a resin component in a thermoplastic resin composition to manufacture absorbent articles in the same manner as conventional hot melt adhesives. Even if they have a reactive functional group, they can be made into a thermoplastic resin composition by forming a resin composition that does not contain a crosslinking agent or catalyst.

[0090] <Optional ingredients> The resin composition may contain, in addition to an easily oxidatively decomposable substance and a compound for generating an easily oxidatively decomposable substance when forming an adhesive joint, a catalyst that is not easily oxidatively decomposable, a crosslinking agent, a solvent, a surfactant, an adhesive, a tackifier, a stabilizer, a plasticizer, a wax, etc.

[0091] <Catalyst> The catalyst is not particularly limited as long as it is a compound that can catalyze the reaction of the crosslinking agent, and compounds that generate radicals by heat, compounds that generate cations by heat, compounds that generate anions by heat, compounds that reduce the activation energy of the crosslinking reaction by coordination, etc. can be used. Specific examples include radical generators such as alkylphenone compounds, benzoin compounds, benzophenone compounds, oxime ester compounds, and phosphine compounds; base generators such as oxime ester compounds, ammonium compounds, benzoin compounds, dimethoxybenzyl urethane compounds, and orthonitrobenzyl urethane compounds; acid generators such as onium salts, halogen-containing compounds, diazomethane compounds, sulfone compounds, and sulfonic acid compounds; tin compounds such as dibutyltin dilaurate and dibutyltin diacetate; bismuth compounds such as bismuth octylate; titanium compounds such as tetraoctyl titanate and titanium ethyl acetoacetate; zirconium compounds such as zirconium monoacetylacetate and zirconium tetraacetylacetate; amines such as triethylenediamine and 1,4-diazabicyclo[2,2,2]octane (DABCO); platinum compounds such as chloroplatinic acid and alkenylsiloxane platinum complexes; iron complexes; and cobalt complexes. The amount of the catalyst in the resin composition is preferably 0.001 to 5 parts by weight, more preferably 0.01 to 3 parts by weight, per 100 parts by weight of the crosslinking agent.

[0092] <Crosslinking agent> Examples of the crosslinking agent include an isocyanate compound, an oxazoline compound, an epoxy compound, an alcohol compound, an amine compound, an alkylene carbonate compound, a haloepoxy compound, a halohydrin compound, a carbodiimide compound, a silane coupling agent, and a polyvalent metal compound.

[0093] Examples of the isocyanate compound include hexamethylene diisocyanate, 2,4-tolylene diisocyanate, etc. Examples of the oxazoline compound include 1,2-ethylenebisoxazoline, etc.

[0094] Examples of epoxy compounds include succinic acid glycidyl ester, sorbitol polyglycidyl ether, trimethylolpropane polyglycidyl ether, polyethylene glycol diglycidyl ether, glycerol polyglycidyl ether, diglycerol polyglycidyl ether, polyglycerol polyglycidyl ether, propylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether, and glycidol.

[0095] Examples of the alcohol compound include ethylene glycol, diethylene glycol, propylene glycol, triethylene glycol, tetraethylene glycol, polyethylene glycol, 1,3-propanediol, dipropylene glycol, 2,2,4-trimethyl-1,3-pentanediol, polypropylene glycol, glycerin, polyglycerin, 2-butene-1,4-diol, 1,3-butanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,2-cyclohexanedimethanol, 1,2-cyclohexanediol, trimethylolpropane, diethanolamine, triethanolamine, polyoxypropylene, oxyethylene-oxypropylene block copolymer, pentaerythritol, and sorbitol.

[0096] Examples of the amine compound include ethylenediamine, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, pentaethylenehexamine, polyethyleneimine, inorganic salts or organic salts (such as azithinium salts) of these amine compounds, and the like.

[0097] Examples of the alkylene carbonate compound include 1,3-dioxolan-2-one, 4-methyl-1,3-dioxolan-2-one, 4,5-dimethyl-1,3-dioxolan-2-one, 4,4-dimethyl-1,3-dioxolan-2-one, 4-ethyl-1,3-dioxolan-2-one, 4-hydroxymethyl-1,3-dioxolan-2-one, 1,3-dioxan-2-one, 4-methyl-1,3-dioxan-2-one, and 4,6-dimethyl-1,3-dioxan-2-one.

[0098] Examples of haloepoxy compounds include epichlorohydrin, epibromohydrin, α-methylepichlorohydrin, and polyamine adducts thereof (eg, Kaimen (registered trademark) manufactured by Hercules).

[0099] The amount of the crosslinking agent in the resin composition is preferably 0.01 to 10 parts by weight, more preferably 0.1 to 5 parts by weight, per 100 parts by weight of the easily oxidatively decomposable substance.

[0100] <Solvent> Examples of the solvent include water and organic solvents, such as ether solvents, amide solvents, hydrocarbon solvents, alcohol solvents, ester solvents, aldehyde solvents, ketone solvents, and solvents containing carbon atoms, such as solvents containing carbon atoms and hetero atoms.

[0101] Examples of ether solvents include propylene glycol monomethyl ether, anisole, 4-methylanisole, diisopropyl ether, diethyl ether, dibutyl ether, tetrahydrofuran, dimethoxyethane, cyclopentyl methyl ether, and tert-butyl methyl ether. Examples of amide solvents include dimethylformamide, dimethylacetamide, and N-methylpyrrolidone. Examples of hydrocarbon solvents include aliphatic hydrocarbon solvents such as pentane, hexane, heptane, octane, nonane, decane, undecane, dodecane, and cyclohexane, and aromatic hydrocarbon solvents such as benzene, toluene, xylene, mesitylene, ethylbenzene, tert-butylbenzene, trifluoromethylbenzene, nitrobenzene, and chlorobenzene. Examples of alcohol solvents include methanol, ethanol, propanol, butanol, ethylene glycol, and propylene glycol monomethyl ether. Examples of ester solvents include ethyl acetate, butyl acetate, and propylene glycol monomethyl ether acetate. Examples of aldehyde solvents include formaldehyde and acetaldehyde. Examples of ketone solvents include acetone, methyl ethyl ketone, and methyl isobutyl ketone. Examples of solvents containing carbon atoms and heteroatoms include acetonitrile and dimethyl sulfoxide. When the resin composition contains a solvent, the amount of the solvent is preferably 1 to 99% by weight, and more preferably 10 to 95% by weight. The resin composition may contain a solvent, but it is preferable that it does not contain one.

[0102] <Surfactant> Examples of surfactants include siloxane compounds such as polyether-modified polydimethylsiloxane, polyether-modified siloxane, polyetherester-modified hydroxyl group-containing polydimethylsiloxane, polyether-modified acrylic group-containing polydimethylsiloxane, polyester-modified acrylic group-containing polydimethylsiloxane, perfluoropolydimethylsiloxane, perfluoropolyether-modified polydimethylsiloxane, and perfluoropolyester-modified polydimethylsiloxane; polyether compounds such as polyoxyethylene alkylphenyl ether, propylene oxide polymer, and ethylene oxide polymer; carboxylic acids such as coconut oil fatty acid amine salts and gum rosin; ester compounds such as castor oil sulfates, phosphate esters, alkyl ether sulfates, sorbitan fatty acid esters, sulfonates, and succinates; and sulfonate compounds such as alkylarylsulfonic acid amine salts and dioctyl sodium sulfosuccinate. The amount of surfactant is preferably 0.01 to 10 wt % of the total solids content of the resin composition, and more preferably 0.1 to 5 wt %.

[0103] <Adhesive> Examples of adhesives include olefin-based hot-melt adhesives including polyolefins and polyolefin copolymers; polyester-based hot-melt adhesives including polyethylene terephthalate, polybutylene terephthalate, and polycaprolactone; rubber-based hot-melt adhesives made from styrene-butadiene-styrene (SBS), styrene-ethylene / butylene-styrene (SEBS), styrene-ethylene / propylene-styrene (SEPS), styrene-isoprene (SI), and styrene-isoprene-styrene (SIS); and reactive urethane hot-melt adhesives made from urethane prepolymers having isocyanate groups at their ends. The amount of adhesive is preferably 0.1 to 70% by weight of the total solids content of the resin composition.

[0104] <Tackifier> Examples of the tackifier include gum rosin, wood rosin, distilled rosin, hydrogenated rosin, polymerized rosin, etc. The amount of the tackifier is preferably 0.01 to 60% by weight of the total solid content of the resin composition.

[0105] <Stabilizer> Examples of the stabilizer include antioxidants such as hindered phenol compounds, sulfur compounds, and phosphorus compounds, and light stabilizers such as benzotriazole compounds, hindered amine compounds, and benzophenone compounds. The amount of the stabilizer in the resin composition is preferably 0.01 to 10% by weight.

[0106] <Plasticizer> Examples of plasticizers include naphthenic oils, paraffinic oils, mineral oils, phthalates, adipates, polybutene, polyisoprene, hydrogenated polyisoprene, polybutadiene, benzoates, animal oils, vegetable oils, glycerol esters of fatty acids, etc. The amount of plasticizer in the resin composition is preferably 0.01 to 40% by weight.

[0107] <Wax> Examples of waxes include paraffin wax, microcrystalline wax, polyethylene wax, and polypropylene wax.

[0108] <Method of manufacturing the adhesive joint> The method for forming the adhesive portion is not particularly limited, and examples include (i) a method of disposing a resin composition on a portion of a back sheet, overlaying a top sheet, and heating or drying the resin composition; (ii) a method of disposing a resin composition on a portion of a top sheet, overlaying a back sheet, and heating or drying the resin composition; and (iii) a method of disposing a resin composition on at least a portion of a core wrap, overlaying the core wrap, and heating or drying the resin composition. Even when the resin composition does not have adhesive properties, for example, a method of disposing a non-degradable adhesive layer on the back sheet, disposing the resin composition, further disposing an adhesive layer, overlaying the top sheet, and heating or drying the resin composition and adhesive composition can be used. Methods for disposing the resin composition on the back sheet or top sheet include applying or impregnating a liquid resin composition, or applying or spraying a solid resin composition. If the resin composition is adhesive, a sheet-like resin composition formed on a release film can be transferred.

[0109] The method for applying the resin composition can be appropriately selected depending on the type of resin composition, core wrap, top sheet, and back sheet, and is not particularly limited. It can be applied by a common method such as slot coater coating, roll coater coating, omega coating, spiral coating, slot spray coating, curtain spray coating, dot coating, control seam coating, bead coating, or letterpress transfer.

[0110] When the resin composition is thermoplastic, the heating temperature is preferably 50 to 160° C. When the resin composition is thermosetting, the heating temperature is preferably 30 to 160° C., more preferably 40 to 120° C. The heating time is preferably 0.5 to 180 minutes, more preferably 0.5 to 30 minutes.

[0111] The thickness of the produced adhesive joint is not particularly limited, but is preferably 0.1 to 300 μm, more preferably 0.5 to 100 μm. Within this range, both adhesive strength and the decomposition and removal rate of easily oxidatively decomposable substances can be achieved.

[0112] <Degraded products> Substances that are easily decomposed by oxidation react with oxidizing agents to produce Z, R 1 , R 2 , or R 3 Preferably, the resulting carboxylic acid, alcohol, amine, or thiol comprises:

[0113] In formula (2), when the hydrazine structure is bonded to the hydrocarbon group in X1a, X1b, X2a, X2b, X3a, X3b, X4a, or X4b, the decomposition products are Z, R 1 , R 2 , or R 3 Specific examples of the carboxylic acid include succinic acid, malonic acid, adipic acid, phthalic acid, trimellitic acid, and polyacrylic acid.

[0114] In formula (2), when the hydrazine structure is bonded to an oxygen atom or a nitrogen atom in X1a, X1b, X2a, X2b, X3a, X3b, X4a, or X4b, the decomposition product becomes an alcohol or an amine. Specific examples of alcohols include ethylene glycol, diethylene glycol, triethylene glycol, hexanediol, pentitol, pentaerythritol, polyethylene glycol, polyvinyl alcohol, resorcinol, and phenol novolak. Specific examples of amines include hexamethylenediamine, pentamethylenediamine, isophoronediamine, toluenediamine, and diaminodiphenylmethane.

[0115] In formula (2), when the hydrazine structure is bonded to the sulfur atoms in X1a, X1b, X2a, X2b, X3a, X3b, X4a, and X4b, the decomposition product becomes a thiol. Specific examples of thiols include pentaerythritol tetrakis(3-mercaptobutyrate), trimethylolpropane, tris(3-mercaptobutyrate), 1,4-bis(3-mercaptobutyryloxy)butane, and triazinethiol.

[0116] The oxidatively decomposable substance preferably generates a water-soluble decomposition product upon reaction with an oxidizing agent. The water solubility of the decomposition product is preferably 1 g / L or more, more preferably 30 g / L or more. The water solubility is measured at 60°C at any one point in the pH range of 2 to 13. The melting point or softening point of the decomposition product is preferably 40°C or less, more preferably 20°C or less. The generation of a water-soluble decomposition product or a decomposition product with a melting point or softening point of 20°C or less shortens the disassembly time of an oxidatively decomposable adhesive joint. In the case of a water-soluble decomposition product, the decomposition product is more likely to dissolve in a solution containing an oxidizing agent. This prevents the accumulation of decomposition product from inhibiting the reaction between the oxidizing agent and the oxidatively decomposable substance, and facilitates the penetration of the solution containing the oxidizing agent into the adhesive joint. The generation of a decomposition product with a melting point or softening point of 20°C or less is thought to cause a significant decrease in adhesive strength. However, the present invention is not limited to these mechanisms.

[0117] <<How to disassemble absorbent articles>> The method for dismantling absorbent articles of the present invention is characterized by including a step of immersing absorbent articles in a solution containing an oxidizing agent at 0 to 60°C. The oxidizing agent is not particularly limited as long as it is an oxidizing agent other than molecular oxygen, and examples thereof include sodium hypochlorite, potassium hypochlorite, calcium hypochlorite, ammonium hypochlorite, chlorinated sodium isocyanurate, potassium chlorinated isocyanurate, calcium chlorinated isocyanurate, ammonium chlorinated isocyanurate, hydrogen peroxide, peracetic acid, m-chloroperbenzoic acid, perbenzoic acid, ammonium hypobromite, calcium hypobromite, potassium hypobromite, sodium hypobromite, and ozone. These may be used alone or in combination of two or more. Among these, water-soluble salts such as sodium hypochlorite, sodium hypobromite, and chlorinated sodium isocyanurate, and ozone water are preferred. These oxidizing agents are preferably used by dissolving them in water or an organic solvent such as ethanol, methanol, isopropanol, or tetrahydrofuran. The solution containing an oxidizing agent may also contain an alkali agent such as sodium hydroxide or potassium hydroxide, a surfactant such as alkylbenzenesulfonate, alkyl sulfate ester salt, alkyl ether carboxylate, polyoxyethylene alkyl ether, glycerin fatty acid ester, alkyltrimethylammonium salt, or alkylcarboxybetaine, etc. The concentration of the oxidizing agent in the solution is preferably 0.001 to 10% by weight, more preferably 0.005 to 2% by weight.

[0118] The temperature condition when the absorbent article is immersed in the solution containing the oxidizing agent is 0 to 60°C, preferably 15 to 50°C. The time condition is preferably 60 minutes or less, more preferably 30 minutes or less. If necessary, the solution may be shaken or stirred during the reaction with the oxidizing agent.

[0119] There are no particular limitations on the method for evaluating the decomposition of adhesive joints upon contact with an oxidizing agent, but it is preferable that the adhesion between the top sheet and the back sheet is released after the absorbent article is immersed in a 1.5% aqueous solution of sodium hypochlorite for 30 minutes.

[0120] When an adhesive or the like that is not easily oxidatively decomposable is included in the adhesive portion, it is preferable to dissolve or disperse it in a solution containing an oxidizing agent by immersion in the solution. This is because the reliability of decomposition of the adhesive portion can be improved. When an adhesive or the like that is not easily oxidatively decomposable does not dissolve in a solution containing an oxidizing agent but can be dissolved or dispersed in water, an acidic aqueous solution, an alkaline aqueous solution, or an organic solvent, the reliability of decomposition of the adhesive portion can be improved by the step of dissolving the adhesive or the like that is not easily oxidatively decomposable in such a solution and the step of immersing in a solution containing an oxidizing agent.

[0121] If the absorbent article is immersed in a solution containing an oxidizing agent to decompose the adhesive joints, the naturally-derived fibers and water-absorbent resin contained in the absorbent core can be separated from the absorbent article by known methods such as specific gravity difference, filtration, centrifugation, vibrating sieve, etc. When the water-absorbent resin is a derivative of polyaspartic acid, cellulose, chitin, chitosan, starch, etc., and is made of a material that can be easily decomposed by acid or alkali, or when it is made of a material that can be decomposed by an oxidizing agent, such as polyacrylic acid having a hydrazine structure, it becomes easy to recover high-purity naturally-derived fibers by adjusting the composition of the decomposition solution.

[0122] On the other hand, when the water-absorbent resin is a typical synthetic resin such as poly(meth)acrylic resin or polyacrylamide resin, the separation of the naturally-derived fibers and the water-absorbent resin can be facilitated by removing a certain amount of water from the water-absorbent resin by adding calcium salts such as calcium chloride, calcium hydroxide, and calcium carbonate, magnesium salts such as magnesium hydroxide, or alkaline agents. Such a decomposition step or dehydration step for the water-absorbent resin may be carried out before or after the decomposition step of the easily oxidatively decomposable substance, or may be carried out simultaneously. When carried out simultaneously, the step is carried out by adding an alkaline agent, calcium salt, or the like to a solution containing an oxidizing agent.

[0123] <<Resin composition for forming adhesive joints>> The resin composition of the present invention is a resin composition for forming the adhesive joint in the absorbent article. The resin composition is not particularly limited as long as it can form an easily oxidatively decomposable layer by heating or drying, but examples include (i) a resin composition containing an easily oxidatively decomposable substance that is easily decomposable by an oxidizing agent, and (ii) a resin composition that generates an easily oxidatively decomposable substance by heating or drying during adhesive joint formation. These compositions are as described above for the absorbent article. [Example]

[0124] The present invention will be described below with reference to examples, but is not limited to the following examples. Hereinafter, "parts" and "%" mean "parts by weight" and "% by weight", respectively, unless otherwise specified.

[0125] (1) Preparation of resin composition (Production Example 1) Resin composition 1 The easily oxidatively decomposable substance A and the components shown in Table 1 were mixed in the following weight ratios. [Table 1]

[0126] Easily oxidatively decomposable substance A was prepared as follows: 300 g of polyether polyol (PREMINOL 5005, manufactured by AGC Corporation), 118 g of acetonitrile, and 46.8 g of triethylamine were mixed in a 1 L separable flask, and 43.4 g of di(N-succinimidyl)carbonate was added and stirred at 25°C for 2 hours. 24.8 g of 6-hydroxyhexane hydrazide was added and stirred at 25°C for 3 hours. After concentration under reduced pressure at 60°C, the mixture was dissolved in 340 g of ethyl acetate, and the organic layer was washed three times with 200 g of ion-exchanged water. The mixture was again concentrated under reduced pressure at 60°C and vacuum-dried overnight at room temperature to obtain 303 g of easily oxidatively decomposable substance A having the structure of formula (A). [ka]

[0127] (Production Example 2) Resin composition 2 Easily oxidatively decomposable substance B was prepared by the following method. 300 g of polyester polyol (Polylite OD-X-2108M, manufactured by DIC Corporation), 228 g of acetonitrile, and 90.1 g of triethylamine were mixed in a 1 L separable flask, and 83.6 g of di(N-succinimidyl) carbonate was added and stirred at 25°C for 1 hour. 47.8 g of 6-hydroxyhexane hydrazide was added and stirred overnight at 25°C. After vacuum concentration at 60°C, the mixture was dissolved in 1050 g of chloroform, and the organic layer was washed four times with 230 g of ion-exchanged water. The chloroform layer was dried over sodium sulfate. The filtrate obtained by vacuum filtration was again vacuum concentrated at 60°C and vacuum dried overnight at room temperature to obtain 345 g of a thermoplastic, easily oxidatively decomposable substance B having the structure of formula (B). The obtained oxidatively decomposable substance B was designated as resin composition 2 and subjected to subsequent evaluation. [ka]

[0128] (Production Example 3) Resin composition 3 Easily oxidatively decomposable substance C was produced by the following method. 5.0 g of polyester polyol (Polylite OD-X-2108M, manufactured by DIC Corporation), 3.8 g of acetonitrile, 1.5 g of triethylamine, and 1.4 g of di(N-succinimidyl) carbonate were added to a test tube and stirred at 25°C for 2 hours. 0.8 g of phenylacetic acid hydrazide was added and stirred at 25°C overnight. After concentration under reduced pressure at 60°C, the mixture was washed with water using chloroform as a good solvent, and the chloroform layer was dried over sodium sulfate. The filtrate obtained by filtration under reduced pressure was concentrated under reduced pressure at 60°C and vacuum dried. 4.6 g of a thermoplastic, easily oxidatively decomposable substance C having the structure of formula (C) was obtained. The obtained oxidatively decomposable substance C was used as resin composition 3 and was subsequently evaluated. [ka]

[0129] (Production Example 4) Resin composition 4 Easily oxidatively decomposable substance D was produced by the following method. 5.0 g of polyester polyol (Polylite OD-X-2108M, manufactured by DIC Corporation), 3.8 g of acetonitrile, 1.5 g of triethylamine, and 1.4 g of di(N-succinimidyl) carbonate were added to a test tube and stirred at 25°C for 2 hours. 0.5 g of adipic acid dihydrazide was added and stirred at 25°C overnight. After concentration under reduced pressure at 60°C, the mixture was washed with water using chloroform as a good solvent, and the chloroform layer was dried over sodium sulfate. The filtrate obtained by filtration under reduced pressure was concentrated under reduced pressure at 60°C and vacuum dried. 2.7 g of a thermoplastic, easily oxidatively decomposable substance D having the structure of formula (D) was obtained. Easily oxidatively decomposable substance D was used as resin composition 4 for subsequent evaluation. [ka]

[0130] (Production Example 5) Resin composition 5 The easily oxidatively decomposable substance B and the components shown in Table 2 were mixed in the following weight ratios. [Table 2]

[0131] (Production Example 6) Resin composition 6 The components listed in Table 3 were mixed in the following weight ratios. [Table 3]

[0132] (Production Example 7) Resin composition 7 10 g of resin composition 6 was mixed with 10 g of ion-exchanged water.

[0133] (2) Preparation of test specimens Test piece A was prepared in such a manner that an easily oxidatively decomposable adhesive portion approximately 5 mm wide was placed on all four sides of a 6 cm square substrate 1 and a 6 cm square substrate 2, approximately 5 mm inward from the edge, and 1.7 g of absorbent 1 or 2 containing a mixture of the components listed in Table 4 was enclosed inside the adhesive portion. [Table 4]

[0134] In addition, test piece B was created in a manner that the entire surface of a 6 cm square substrate 2 had an easily oxidatively decomposable adhesive portion, and the 1.7 g of absorbent 1 or 2 was adhered from the center of substrate 2 to approximately 5 mm inside the edge of substrate 2, and all four sides of the portion approximately 5 mm from the edge were adhered to substrate 1, thereby fixing the absorbent inside.

[0135] The configurations of the substrates 1 and 2 and the adhesive joints of each test piece are shown in Tables 7 and 8. The manufacturing method of each adhesive joint is also described below.

[0136] (2-1) Adhesion by Curing of Resin Composition 1 (Adhesion Part I, Examples 1 and 2) Resin composition 1 was applied onto substrate 2 shown in Table 7, and then substrate 1 was attached. Thereafter, resin composition 1 was cured by keeping the temperature at 70°C for 2.5 hours. As a result, substrate 1 and substrate 2 were bonded via adhesive part I made of resin composition 1.

[0137] (2-2) Adhesion by heating of resin composition 2 (adhesion part II, Example 3) Resin composition 2 heated to 70°C was applied onto substrate 2, and then substrate 1 was attached, pressed, and allowed to cool, thereby bonding substrate 1 and substrate 2 via adhesive part II consisting of resin composition 2.

[0138] (2-3) Adhesion by heating of resin composition 3 (adhesion part III, Examples 4 and 10) Resin composition 3 heated to 100°C was applied onto substrate 2, and then substrate 1 was attached, pressed, and allowed to cool, thereby bonding substrate 1 and substrate 2 via adhesive part III made of resin composition 3.

[0139] (2-4) Adhesion by heating of resin composition 4 (adhesion part IV, Examples 5, 11, and 12) Resin composition 4 heated to 120°C was applied onto substrate 2, and then substrate 1 was attached, pressed, and allowed to cool, thereby bonding substrate 1 and substrate 2 via adhesive joint IV made of resin composition 4.

[0140] (2-5) Adhesion by heating of resin composition 5 (adhesion part V, Example 6) Resin composition 5 heated to 100°C was applied onto substrate 2, and then substrate 1 was attached, pressed, and allowed to cool, thereby bonding substrate 1 and substrate 2 together via adhesive part V made of resin composition 5.

[0141] (2-6) Adhesion by curing of resin composition 6 (adhesion part VI, Example 7) Resin composition 6 was applied onto substrate 2, and then substrate 1 was attached. Resin composition 6 was then cured by keeping the temperature at 70°C for 3 hours. As a result, substrate 1 and substrate 2 were bonded via adhesive joint VI consisting of resin composition 6. It was estimated from the oxidative decomposition product that this curing reaction produced an easily oxidatively decomposable substance E having a structure of formula (E) in which the hydrazide group of citric acid trihydrazide was added to the epoxy group of polyglycerol polyglycidyl ether in the adhesive joint. [ka]

[0142] (2-7) Bonding of cured resin composition 7 with adhesive composition (bonding part VII, Example 8) Substrate 1 shown in Table 8 was impregnated with resin composition 7, excess liquid was removed with a squeeze roll, and the substrate was spread on release paper and incubated at 70°C for 3 hours, followed by leaving it to stand at room temperature overnight, thereby laminating a cured product of resin composition 7 on the surface of substrate 1. This resin composition 7 did not exhibit adhesive properties after the curing reaction. It was estimated from the oxidative decomposition product that this curing reaction produced in the cured product an easily oxidatively decomposable substance E having a structure of formula (E) in which the hydrazide group of citric acid trihydrazide was added to the epoxy group of polyglycerol polyglycidyl ether.

[0143] On the other hand, an adhesive composition prepared by mixing the components listed in Table 5 at 120°C was applied to substrate 2, and then a laminate of substrate 1 and the cured product of resin composition 7 was attached to each other with the cured product of resin composition 7 in contact with the adhesive composition, followed by pressure bonding and cooling. As a result, substrate 1 and substrate 2 were bonded via a two-layer adhesive joint VII consisting of the cured product of resin composition 7 and the adhesive. [Table 5]

[0144] (2-8) Bonding of cured resin composition 7 with adhesive composition (bonding part VIII, Example 9) Resin composition 7 was applied to substrate 1 and substrate 2, and the resulting mixture was incubated at 70°C for 3 hours, and then allowed to stand at room temperature overnight, thereby laminating a cured product of resin composition 7 on the surfaces of substrate 1 and substrate 2. This cured product of resin composition 7 did not have any adhesive properties.

[0145] Next, an adhesive composition prepared by mixing the components listed in Table 4 at 120°C was applied to a laminate of the above-mentioned substrate 2 and the cured product of resin composition 7. The laminate of the above-mentioned substrate 1 and the cured product of resin composition 7 was then bonded together and allowed to cool, thereby bonding substrate 1 and substrate 2 via a three-layer adhesive joint VIII consisting of two layers of the cured product of resin composition 7 and one adhesive layer. It was estimated from the oxidative decomposition product that this curing reaction produced an easily oxidatively decomposable substance E having the structure of formula (E) in the adhesive joint.

[0146] (3) Disassembly test Each test piece was immersed in physiological saline for 10 minutes, and then the test piece after absorbing water was transferred to a beaker containing 300 ml of a decomposition solution containing the components shown in Table 6, and stirred for 30 minutes at the temperatures shown in Tables 7 and 8. Substrates 1 and 2 were then recovered and dried, after which the weight of the absorbent remaining in the test piece was measured and evaluated according to the following criteria. The evaluation results are shown in Tables 7 and 8. 〇: Less than 0.3g △: 0.3g or more and less than 1.0g ×: 1.0g or more

[0147] [Table 6]

[0148] (4) Adhesive strength Using the same combination of substrate and adhesive part as in Examples 1 to 12, one side of substrate 1 and one side of substrate 2 were bonded together. Opposite sides of the bonded sides were firmly grasped with each hand and then pulled in a straight line (at an angle of 180 degrees to each other) to separate them. The adhesive strength was evaluated by checking the peeled surfaces of substrate 1 and substrate 2. The evaluation results are shown in Tables 7 and 8. ○: Material destruction of the substrate was observed △: Cohesive failure was observed in the adhesive joint ×: Interfacial failure was observed between the adhesive part and the substrate.

[0149] [Table 7] [Table 8]

[0150] In Examples 1 to 12, sufficient adhesive strength was observed in the easily oxidatively decomposable adhesive joints. Furthermore, after the absorbent article was immersed in a decomposition liquid containing an oxidizing agent, only a small amount of absorbent remained in the test piece, and the absorbent could be efficiently recovered.

[0151] The present invention may include, for example, the following aspects. <1> A top sheet, a back sheet, and an absorbent body, The absorbent article has the top sheet and the back sheet bonded together via an easily oxidatively decomposable adhesive portion. <2> Item 1. The absorbent article according to item 1, further comprising a core wrap. <3> Item 3. The absorbent article according to item 2, wherein the absorbent body and at least one selected from the group consisting of the top sheet, the back sheet, and the core wrap are bonded via an easily oxidatively decomposable adhesive. <4> Item 4. The absorbent article according to Item 2 or 3, wherein the core wraps are bonded to each other or to the backsheet via an easily oxidatively decomposable adhesive. <5> Item 5. The absorbent article according to any one of items 1 to 4, wherein the adhesive portion contains an easily oxidatively decomposable substance. <6> Item 6. The absorbent article according to any one of items 1 to 5, wherein the adhesive portion comprises a layer containing an easily oxidatively decomposable substance and adhesive layers formed on both sides thereof. <7> Item 7. The absorbent article according to item 5 or 6, wherein the layer containing the easily oxidatively decomposable substance is thermoplastic or thermosetting. <8> The easily oxidatively decomposable substance has a hydrazine structure represented by formula (1), Item 8. The absorbent article according to any one of items 1 to 7. -A I -NH-NH-A II - (1) (In formula (1), A I , A II are carbonyl groups or single bonds, and A I and A II At least one of the groups is a carbonyl group. <9> Item 9. The absorbent article according to item 8, wherein the easily oxidatively decomposable substance is represented by formula (2). [ka] (In formula (2), ·n≧0, k≧0, m≧0, p1≧1, p2≧1, p3≧1. ·R 1 , R 2 , R 3 are each independently a divalent group containing a siloxane structure, or a hydrocarbon group which may have a substituent or a heteroatom. X 1a , X 1b , X 2a , X 2b , X 3a , X 3b , X4a , X 4b are each independently an oxygen atom, a sulfur atom, a single bond, a hydrocarbon group having 1 to 20 carbon atoms which may have a substituent, or -NB- (B is a hydrogen atom or a hydrocarbon group). A 1 ~A 8 are each independently a carbonyl group or a single bond, and A 1 and A 2 At least one of A is a carbonyl group, 3 and A 4 At least one of A is a carbonyl group, 5 and A 6 At least one of A is a carbonyl group, 7 and A 8 At least one of the groups is a carbonyl group. Q 1 , Q 2 , Q 3 are each independently hydrogen or a substituent. Z's are each independently a divalent or higher polyvalent group containing a siloxane structure, or a hydrocarbon group having 1 to 500 carbon atoms and optionally containing a hetero atom. <10> Substances that are easily oxidatively decomposed react with oxidizing agents to form Z, R 1 , R 2 , or R 3 Item 10. The absorbent article according to item 9, which produces a carboxylic acid, alcohol, amine, or thiol comprising: <11> Item 11. The absorbent article according to any one of items 5 to 10, wherein the easily oxidatively decomposable substance generates a water-soluble decomposition product upon reaction with an oxidizing agent. <12> Item 12. The absorbent article according to any one of items 1 to 11, wherein the absorbent body contains an absorbent resin and / or naturally derived fibers. <13> The top sheet and the back sheet are bonded together by a rectangular adhesive portion that surrounds the absorbent body and / or the core wrap, two or more sides of the rectangular adhesive portion contain an easily oxidatively decomposable substance, At least one long side is an adhesive portion containing an easily oxidatively decomposable substance; Item 13. The absorbent article according to any one of items 1 to 12. <14> Item 14. The absorbent article according to any one of items 2 to 13, wherein the absorbent body is sandwiched between two or more core wraps, and the two or more core wraps are bonded together by adhesive parts made of an easily oxidatively decomposable substance. <15> 15. A method for dismantling absorbent articles, comprising the step of immersing the absorbent article according to any one of items 1 to 14 in a solution containing an oxidizing agent at 0 to 60°C. <16> Item 15. A composition for forming the adhesive part in the absorbent article according to any one of items 1 to 14. [Explanation of symbols]

[0152] 10 Absorbent articles 11 Topsheet 12 Core Wrap 13 Back Seat 14 Adhesive part 15 Absorbent 101 Topsheet or Core Wrap 102 Backsheet or Core Wrap 103 Easily oxidatively decomposable layer 104 Adhesive layer 105 Layer that is easily oxidatively decomposable and contains adhesive

Claims

1. A top sheet, a back sheet, and an absorbent body, The absorbent article has the top sheet and the back sheet bonded together via an easily oxidatively decomposable adhesive portion.

2. The absorbent article of claim 1 further comprising a core wrap.

3. The absorbent article according to claim 2, wherein the absorbent body and at least one selected from the group consisting of the top sheet, the back sheet, and the core wrap are bonded via an easily oxidatively decomposable adhesive.

4. The absorbent article according to claim 2 or 3, wherein the core wraps are bonded to each other or the core wrap and the backsheet are bonded to each other via an adhesive that is easily oxidatively decomposable.

5. The absorbent article according to claim 1 , wherein the adhesive portion comprises a substance that is easily oxidatively decomposed.

6. The absorbent article according to claim 1 , wherein the adhesive portion comprises a layer containing an easily oxidatively decomposable substance and adhesive layers formed on both sides of the layer.

7. The absorbent article according to claim 5 or 6, wherein the layer containing the easily oxidatively decomposable substance is thermoplastic or thermosetting.

8. The easily oxidatively decomposable substance has a hydrazine structure represented by formula (1), The absorbent article according to claim 5 or 6. -A Ｉ -NH-NH-A ＩＩ - (1) (In formula (1), A Ｉ , A ＩＩ are each a carbonyl group or a single bond, and A Ｉ and A ＩＩ At least one of the groups is a carbonyl group.

9. The absorbent article according to claim 8, wherein the easily oxidatively decomposable substance is represented by formula (2). 【Chemical 1】 (In formula (2), ・n≧0, k≧0, m≧0, p1≧1, p2≧1, p3≧1. ・R １ , R ２ , R ３ are each independently a divalent group containing a siloxane structure, or a hydrocarbon group which may have a substituent or a heteroatom. ・X １ａ , X １ｂ , X ２ａ , X ２ｂ , X ３ａ , X ３ｂ , X ４ａ , X ４ｂ are each independently an oxygen atom, a sulfur atom, a single bond, a hydrocarbon group having 1 to 20 carbon atoms which may have a substituent, or -NB- (B is a hydrogen atom or a hydrocarbon group). ・A １ ~A ８ are each independently a carbonyl group or a single bond, and A １ and A ２ At least one of A is a carbonyl group, ３ and A ４ At least one of A is a carbonyl group, ５ and A ６ At least one of A is a carbonyl group, ７ and A ８ At least one of the groups is a carbonyl group. ・Q １ , Q ２ , Q ３ are each independently hydrogen or a substituent. Each Z is independently a divalent or higher valent group containing a siloxane structure, or a hydrocarbon group having 1 to 500 carbon atoms and optionally containing a hetero atom.

10. The substance that is easily oxidatively decomposed reacts with an oxidizing agent to form Z, R １ , R ２ , or R ３ 10. The absorbent article of claim 9, which produces a carboxylic acid, alcohol, amine, or thiol comprising:

11. The absorbent article according to claim 5 or 6, wherein the easily oxidatively decomposable substance generates a water-soluble decomposition product upon reaction with an oxidizing agent.

12. The absorbent article according to claim 1 or 2, wherein the absorbent body comprises an absorbent resin and / or a naturally derived fiber.

13. The top sheet and the back sheet are bonded together by a rectangular adhesive portion that surrounds the absorbent body and / or the core wrap, two or more sides of the rectangular adhesive portion contain an easily oxidatively decomposable substance, At least one long side is an adhesive portion containing an easily oxidatively decomposable substance; The absorbent article according to claim 1 or 2.

14. 3. The absorbent article according to claim 2, wherein the absorbent body is sandwiched between two or more core wraps, and the two or more core wraps are bonded together by an adhesive that is easily oxidatively decomposable.

15. A method for dismantling absorbent articles, comprising the step of immersing the absorbent article according to claim 1 or 2 in a solution containing an oxidizing agent at 0 to 60°C.

16. A composition for forming the adhesive portion in the absorbent article according to claim 1 or 2.

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