JP7144952B2 - disposable diaper - Google Patents

Description

The present invention relates to disposable diapers, and more particularly to disposable diapers having fastening means.

Disposable diapers have been proposed that have fastening means. In a disposable diaper having such fastening means, a load is likely to be applied to the joint between the fastening base material constituting the fastening means and the main body of the diaper, and peeling or breakage of the joint may occur. Therefore, it is important to ensure the strength of the joint between the fastening base material and the diaper body.

As a disposable diaper having such fastening means, one in which the bonding strength of the bonding portion is improved has been proposed. For example, in Patent Document 1, a fastening base material joint portion has a plurality of adhesive application regions, and the adhesive applied to the plurality of adhesive application regions includes a rubber adhesive and an olefin adhesive. Disposable diapers have been proposed (see Patent Document 1 (claim 2, paragraph 0006)).

It has also been proposed to improve the joint strength of the joint between the fastening base material and the surface fastener when the surface fastener is used as the fastening means. For example, Patent Document 2 discloses a polyurethane prepolymer obtained by polyaddition of at least one polyol to at least one diisocyanate trimerized as an isocyanurate, and a reaction product of the diisocyanate and water. Hygienic with a fixing element in the form of a woven mesh bonded by an adhesive in which the content of free NCO groups of the prepolymer is 1-25% by weight Articles have been proposed (see Patent Document 2 (claim 12, paragraphs 0004 and 0005)).

JP 2011-097975 A Japanese Patent Publication No. 2001-527117

When the wearer of the disposable diaper uses a heater (electric blanket, kotatsu, etc.), the joint between the fastening member and the diaper body is warmed. As a result, the hot-melt adhesive used to join the fastening member and the diaper main body may soften and the fastening member may come off from the diaper main body.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and provides a disposable diaper in which the fastening member is prevented from coming off from the main body of the diaper even when the wearer of the disposable diaper having the fastening member uses a heating device. The task is to

The disposable diaper of the present invention comprises a diaper body having an absorbent core, left and right fastening members respectively joined to both side edge portions of a rear portion of the diaper body and extending outward in the width direction from the diaper body, and the left and right fastening members. A first fastening member provided on the skin surface side of each member, and a second fastening member provided on the outer surface side of the front portion of the diaper body, to which the first fastening member is detachably fastened. , wherein the diaper body and the fastening member are joined by a cured reactive urethane hot-melt adhesive.

In the disposable diaper of the present invention, the diaper main body and the fastening member are joined by a cured reactive urethane hot-melt adhesive. The reactive urethane hot-melt adhesive used in the present invention cures by reacting with moisture in the air to form three-dimensional crosslinks. That is, the cured product of the reactive urethane hot-melt adhesive is not plasticized by heating. Therefore, even when the wearer uses a heating device, the hardened reactive urethane hot-melt adhesive that joins the diaper body and the fastening member does not soften, and the fastening member does not come off from the diaper body. Suppressed.

It is preferable that at least one of the skin surface side and the outer surface side of the fixed end portion of the fastening member is joined to the diaper main body only by the cured reactive urethane hot-melt adhesive. For example, one of the skin surface side and the outer surface side of the fixed end portion of the fastening member is joined to the diaper body only by the cured reactive urethane hot-melt adhesive, and the other is joined only by the non-reactive hot-melt adhesive. It is preferably joined to the diaper body.

Both side edges of the rear part of the diaper body have a structure with a weight per unit area of 22 g/m ² to 50 g/m ² in which at least two polypropylene nonwoven fabrics are laminated, and the fixed end portion of the fastening member is formed of the at least two sheets. It is preferably sandwiched between two non-woven fabrics and joined by a cured product of a reactive urethane tot-melt adhesive.

It is preferable that the fixed end portion of the fastening member is made of spunbond nonwoven fabric made of polypropylene and having a basis weight of 45 g/m ² to 80 g/m ² .

The diaper body has, for example, a back sheet, the absorbent core arranged on the skin surface side of the back sheet, and a top sheet arranged on the skin surface side of the absorbent core, and the fixed end portion of the fastening member is , is sandwiched between the top sheet and the back sheet, and is joined by a cured product of a reactive urethane hot-melt adhesive.

The diaper body includes, for example, a back sheet, the absorbent core provided on the skin side of the back sheet, a top sheet provided on the skin side of the absorbent core, and both sides in the width direction of the top sheet. The fixed ends of the fastening members are sandwiched between the side sheets and the back sheet and joined by a cured reactive urethane hot-melt adhesive.

The coating amount of the cured reactive urethane hot-melt adhesive at the joint between the material forming the main body of the diaper and the fastening member is preferably 5 g/m ² to 100 g/m ² .

ADVANTAGE OF THE INVENTION According to this invention, even when a wearer uses a heating appliance, the disposable diaper from which detachment|separation from the diaper main body of the fastening member is suppressed is obtained.

BRIEF DESCRIPTION OF THE DRAWINGS The top view which looked at an example of the disposable diaper of this invention from the top sheet side. The top view which looked at the disposable diaper of FIG. 1 from the back sheet|seat side. FIG. 2 is a schematic cross-sectional view taken along line VV of FIG. 1; FIG. 4 is an explanatory diagram illustrating a joining state between a fastening member and a diaper main body; FIG. 4 is an explanatory diagram illustrating a joining state between a fastening member and a diaper main body; FIG. 2 is a perspective view showing the state in which the disposable diaper of FIG. 1 is worn; Explanatory drawing about the manufacturing process of a fastening member. Explanatory drawing which illustrates the process of apply|coating a hot melt adhesive to a fastening base-material continuous body. Side view of the coater head. FIG. 10 is an exploded perspective view of the coater head of FIG. 9; Explanatory drawing explaining the adhesive strength test method of a fastening member.

The disposable diaper of the present invention comprises a diaper body having an absorbent core, left and right fastening members respectively joined to both side edge portions of a rear portion of the diaper body and extending outward in the width direction from the diaper body, and the left and right fastening members. A first fastening member provided on the skin surface side of each member, and a second fastening member provided on the outer surface side of the front portion of the diaper body, to which the first fastening member is detachably fastened. , wherein the diaper body and the fastening member are joined by a cured reactive urethane hot-melt adhesive.

The reactive urethane hot-melt adhesive is a moisture-curable adhesive that reacts with moisture in the air to form three-dimensional crosslinks and cure. In other words, the cured product of the reactive urethane hot-melt adhesive is not softened by heating and has excellent heat resistance. Therefore, the disposable diaper of the present invention can prevent the fastening member from coming off from the diaper body even when the wearer uses a heater to heat the joint between the diaper body and the fastening member. In addition, the reactive urethane hot melt adhesive can be applied in a molten state in the same manner as conventional hot melt adhesives, and can be temporarily bonded to adherends by cooling and solidifying. Therefore, by using a reactive urethane hot-melt adhesive, it is possible to use conventional manufacturing equipment and to suppress a decrease in productivity.

(reactive urethane hot melt adhesive)
First, a reactive urethane hot-melt adhesive used for joining fastening members will be described. The reactive urethane hot-melt adhesive is moisture-curable. The reactive urethane hot-melt adhesive contains a urethane prepolymer having an isocyanate group at the end of the molecular chain.

The urethane prepolymer is preferably obtained by reacting a polyol and a polyisocyanate under conditions in which isocyanate groups are excessive.

Examples of the polyol include, but are not particularly limited to, polyether polyol, polyester polyol, polycarbonate polyol, polycaprolactone, and the like. Mention may also be made of triols such as trimethylolpropane.

Said polyisocyanate is a compound having at least two isocyanate groups in the molecule. Examples of the polyisocyanate include yellowing type diisocyanates such as diphenylmethane diisocyanate, dimethyldiphenylmethane diisocyanate, tolylene diisocyanate and phenylene diisocyanate; Mention may be made of yellowing diisocyanates. The reactive urethane hot-melt adhesive used in the present invention preferably contains a non-yellowing diisocyanate or a non-yellowing diisocyanate as a polyisocyanate component.

The isocyanate group content of the reactive urethane hot-melt adhesive used in the present invention is preferably 1% by mass or more, more preferably 3% by mass or more, still more preferably 5% by mass or more, and 25% by mass or less. It is preferably 23% by mass or less, more preferably 21% by mass or less. When the isocyanate group content is 1% by mass or more, moisture curability is easily exhibited, and when the content is 25% by mass or less, adhesive strength after curing is improved.

The melt viscosity of the reactive urethane hot-melt adhesive at 120° C. is preferably 2,000 mPa·s or more, more preferably 4,000 mPa·s or more, still more preferably 6,000 mPa·s or more, and 20,000 mPa·s. The following is preferable, 15,000 mPa·s or less is more preferable, and 10,000 mPa·s or less is even more preferable. If the melt viscosity of the reactive urethane hot-melt adhesive is within the above range, the reactive urethane hot-melt has good coatability.

The open time of the reactive urethane hot melt adhesive used in the present invention is preferably 10 seconds or longer, more preferably 15 seconds or longer, still more preferably 20 seconds or longer, and 60 seconds or shorter. It is preferably 50 seconds or less, more preferably 40 seconds or less. This is because if the open time of the reactive urethane hot-melt adhesive is within the above range, the adhesive strength of the joint is likely to be improved.

(Non-reactive hot melt adhesive)
In the disposable diaper of the present invention, non-reactive hot-melt adhesives are preferably used for bonding other components. The non-reactive hot-melt adhesive is applied to an object to be adhered in a state of being softened or melted by heating, and develops adhesive strength by cooling to room temperature and solidifying. Examples of non-reactive hot-melt adhesives include rubber-based hot-melt adhesives, olefin-based hot-melt adhesives, polyamide-based hot-melt adhesives, and polyester-based hot-melt adhesives.

The rubber-based hot-melt adhesive preferably contains a synthetic rubber, more preferably a styrene block copolymer, as a base polymer. Examples of the synthetic rubber include styrene-acrylonitrile, acrylonitrile-butadiene-styrene, styrene-butadiene rubber, butadiene-styrene elastomer, styrene-isoprene (SI), styrene-isoprene-styrene (SIS), styrene-butadiene-styrene ( SBS), styrene-ethylene/butylene-styrene (SEBS), and at least one selected from the group consisting of styrene-ethylene/propylene-styrene (SEPS). Among these, synthetic rubbers include styrene-isoprene (SI), styrene-isoprene-styrene (SIS), styrene-butadiene-styrene (SBS), styrene-ethylene/butylene-styrene (SEBS), and styrene-ethylene /propylene-styrene (SEPS). The styrene block copolymer can have a linear molecular structure or a radial molecular structure.

The olefinic hot melt adhesive preferably contains an olefinic polymer. Examples of the olefin-based polymer include polyolefins, polyolefin copolymers, and olefin/α-olefin interpolymers. Examples of the olefin-based polymer include amorphous, semi-crystalline, and crystalline polymers. For example, amorphous polyolefin can be preferably used.

Examples of olefinic polymers include ethylene/vinyl acetate (EVA), ethylene/acrylate, ethylene/methacrylate, ethylene/n-butyl acrylate, ethylene/n-hexyl acrylate, ethylene/propylene, ethylene/butene, ethylene/octene, Polypropylene etc. are mentioned. The olefinic polymer may be used alone or in combination of two or more.

The reactive urethane hot melt adhesives and non-reactive hot melt adhesives can contain tackifiers, plasticizers, waxes, and the like.

Examples of the tackifier include gum rosin, wood rosin, tall oil rosin, distilled rosin, hydrogenated rosin, dimerized rosin, and polymerized rosin.

Examples of the plasticizer include naphthenic oils, paraffinic oils (e.g., cycloparaffinic oils), mineral oils, phthalate esters, adipate esters, olefin oligomers (e.g., oligomers of polypropylene, polybutene and hydrogenated polyisoprene). ), polybutene, polyisoprene, hydrogenated polyisoprene, polybutadiene, benzoic acid esters, animal oils, vegetable oils (e.g., castor oil, soybean oil), oil derivatives, glycerol esters of fatty acids, polyesters, polyethers, etc. can.

Said waxes include, for example, paraffin waxes, microcrystalline waxes, polyethylene waxes, polypropylene waxes, by-product polyethylene waxes, Fischer-Tropsch waxes, oxidized Fischer-Tropsch waxes, and functionalized waxes such as hydroxystearamide waxes and fatty amide waxes. Base wax etc. can be mentioned.

The reactive urethane hot-melt adhesives and non-reactive hot-melt adhesives may further contain additives such as stabilizers, antioxidants, pigments, dyes, and UV absorbers.

(disposable diaper)
Next, the structure of the disposable diaper of the present invention will be explained. The disposable diaper includes: a diaper main body; left and right fastening members respectively joined to both side edge portions of a rear portion of the diaper main body and extending outward in a width direction from the diaper main body; It has first fastening members provided respectively, and second fastening members provided on the outer surface side of the front portion of the diaper body and to which the first fastening members are detachably fastened.

The diaper body has an absorbent core that absorbs liquid and is applied to the wearer. The diaper body has a front portion, a crotch portion, and a rear portion. The front portion is applied to the abdomen of the wearer, the rear portion is applied to the back of the wearer, and the crotch portion is applied to the crotch of the wearer. In addition, in the diaper main body and the fastening member, the side facing the wearer's skin when worn is the skin surface side, and the back surface of the skin side is the outer surface side.

The diaper body has an absorbent core that absorbs liquid. The absorbent core absorbs and retains excretory fluids excreted by the wearer (for example, water contained in urine and feces). Specifically, the absorbent core contains water-absorbing resin powder and/or water-absorbing fibers. As the water absorbent resin powder, those conventionally used in absorbent articles can be used. Examples of the water-absorbent resin powder include synthetic polymer-based water-absorbent resin powders such as polyacrylate, polysulfonate, maleic anhydride, polyacrylamide, polyvinyl alcohol, and polyethylene oxide; and , polyglutamic acid-based, polyalginic acid-based, starch-based, and cellulose-based water absorbent resin powders derived from natural products. Examples of the water-absorbing fibers include pulp fibers, cellulose fibers, rayon, and acetate fibers. The planar view shape of the absorbent core is not particularly limited, and examples thereof include a rectangular shape, an hourglass shape, a gourd shape, and a battledore shape.

The diaper body preferably has a top sheet arranged on the skin surface side of the absorbent core and a back sheet arranged on the outer surface side of the absorbent core.

The top sheet is liquid-permeable and quickly permeates excretions from the wearer. Examples of the top sheet include a nonwoven fabric formed of hydrophilic fibers. Examples of the hydrophilic fibers include cellulose, rayon, and cotton. Examples of the nonwoven fabric include point-bond nonwoven fabric, air-through nonwoven fabric, spunlace nonwoven fabric, spunbond nonwoven fabric, and air-laid nonwoven fabric. The shape of the top sheet is not particularly limited, and examples thereof include a rectangle, an hourglass shape, a gourd shape, a battledore shape, etc., preferably a rectangle.

The back sheet may be either a liquid-permeable sheet or a liquid-impermeable sheet, but a liquid-impermeable sheet is preferred. A liquid-impermeable sheet can prevent excreted liquid that has reached the back sheet from seeping out to the outer surface side of the main body of the diaper. As the liquid-impermeable sheet, a water-repellent or liquid-impermeable nonwoven fabric (e.g., spunbond nonwoven fabric, meltblown nonwoven fabric, SMS (spunbond・Meltblown/spunbond) non-woven fabric) and water-repellent or liquid-impermeable plastic films can be used. The shape of the backsheet is not particularly limited, and examples thereof include a rectangular shape, an hourglass shape, a gourd shape, and a battledore shape, with the hourglass shape and the gourd shape being preferred.

Also, the back sheet may be a laminated sheet composed of a liquid-impermeable sheet and a non-woven fabric bonded to the outer surface of the liquid-impermeable sheet. When the backsheet is a laminated sheet consisting of a liquid-impermeable sheet and a non-woven fabric laminated to the outside of the liquid-impermeable sheet, the liquid-impermeable sheet is arranged on both side edges of the rear portion of the backsheet. It is preferable that the non-woven fabric is used instead of the non-woven fabric.

The basis weight of the nonwoven fabric used for the backsheet is preferably 10 g/m ² or more, more preferably 12 g/m ² or more, still more preferably 13 g/m ² or more, preferably 25 g/m ² or less, and 21 g/m ² or less. More preferably, it is 18 g/m ² or less.

As the nonwoven fabric used for the back sheet, it is preferable to use a polypropylene (resin) nonwoven fabric obtained by the SMMS (spunbond-meltblown-meltblown-spunbond) method.

The diaper main body may have left and right side sheets on the skin surface side. It is preferable that the left and right side sheets are joined to both side edges of the skin surface of the top sheet along the longitudinal direction (front-rear direction) with a gap in the width direction on the skin surface side of the top sheet. The side sheets on the inner side in the width direction from the joining point between the side sheets and the top sheet are not joined to the top sheet and are free ends. Elastic members that are elongated in the front-rear direction are arranged at the inner ends (upper ends when the vehicle is standing) of the left and right side seats. The inner ends of the left and right side sheets are configured to be able to stand up in the direction away from the top sheet (skin surface side) due to the contractile force of the elastic members. The side sheet and the elastic member constitute a three-dimensional gather, and the three-dimensional gather prevents excreted urine and feces from leaking sideways. As the side sheet, a water-repellent or liquid-impermeable nonwoven fabric (e.g., spunbond nonwoven fabric, meltblown nonwoven fabric, SMMS (spunbond meltblown nonwoven fabric) made of hydrophobic fibers (e.g., polypropylene, polyethylene, polyester, polyamide)・It is preferable to use meltblown spunbond) nonwoven fabric).

Although the shape of the side sheet is not particularly limited, it is preferable that the side sheet has a shape that covers both sides of the back sheet. .

The basis weight of the nonwoven fabric used for the side sheets is preferably 12 g/m ² or more, more preferably 14 g/m ² or more, still more preferably 15 g/m ² or more, preferably 25 g/m ² or less, and 21 g/m ² or less. More preferably, it is 18 g/m ² or less.

As the nonwoven fabric used for the side sheets, it is preferable to use a nonwoven fabric made of polypropylene (resin) obtained by the SMMS (spunbond-meltblown-meltblown-spunbond) method.

The diaper main body is provided with a second fastening member on the outer surface side of the front portion. The second fastening member can be detachably attached to a first fastening member of a fastening member to be described later. The position and range where the second fastening member is provided may be appropriately adjusted according to the shape of the fastening member and the position of the first fastening member, which will be described later.

The disposable diaper of the present invention has fastening members. The left and right fastening members are joined to both side edge portions of the rear portion of the diaper body, and are formed to extend outward in the width direction from the diaper body. The fastening member has a fastening base material and a first fastening member provided on the skin surface side of the fastening base material. The fastening base material has a fixed end to be joined to the diaper body and a tip to which the first fastening member is provided. A pair of left and right fastening members provided with first fastening members and a second fastening member provided on the diaper main body constitute fastening means. The fastening means is used to fasten the front part and the rear part of the diaper main body to form the waist when the disposable diaper is put on.

The fastening base material can be appropriately selected from, for example, nonwoven fabrics, woven fabrics, knitted fabrics, and resin film materials. The fastening base material is preferably a nonwoven fabric manufactured by one or a combination of manufacturing methods selected from the spunbonding method, the air-through method, the point bonding method, the melt blowing method, and the airlaid method. Further, a nonwoven fabric having a basis weight of 30 g/m ² to 100 g/m ² and manufactured by a spunbond method or an SMMS method combining a spunbond method and a melt blow method is preferable from the viewpoint of strength. The most preferred fastening base material is a nonwoven fabric with a basis weight of 45 g/m ² to 80 g/m ² and produced by a spunbond method. The material can be appropriately selected from synthetic fibers such as polypropylene, polyethylene, polyester and polyamide, and natural fibers such as pulp and silk, but preferably synthetic fibers such as polypropylene, polyethylene and polyester can be used. As the fastening base material, those containing polypropylene or polyester fiber as a main component are strong and suitable. The most preferred material for the fastening base material is polypropylene fiber.

The first fastening member and the second fastening member are not particularly limited as long as they can be detachably fastened. As a combination of the first fastening member and the second fastening member, for example, a mode in which the first fastening member and the second fastening member constitute a hook-and-loop fastener; the first fastening member is an adhesive tape, A mode in which the second fastening member is an adhesive sheet to which the adhesive tape can be attached in a detachable manner. In addition, when adopting a hook-and-loop fastener, it is preferable to arrange a hook material on the first fixing member and arrange a loop material on the second fixing member.

As the first fastening member, for example, a hook material in which a plurality of hooks are densely provided in a planar shape is preferably used. The shape of the hook of the hook material is preferably an anchor shape, a piece shape, a mushroom shape, or the like. Examples of the hook material include "Velcro (registered trademark)" (manufactured by Kuraray Co., Ltd.), "Quicklon (registered trademark)" (manufactured by YKK), and "Majicross (registered trademark)" (manufactured by Kanebo Belltouch). can be used. As the second fastening member, for example, a loop material (non-woven fabric, woven fabric, knitted fabric, etc., resin film composite material having a non-woven fabric, woven fabric, etc. on the surface) in which a fine loop structure is densely provided in a planar shape is used. Used.

In the disposable diaper of the present invention, the diaper body and the fastening member are joined by a cured reactive urethane hot-melt adhesive. It is preferable that at least one of the skin surface side and the outer surface side of the fixed end portion of the fastening member is joined to the diaper main body only by the cured reactive urethane hot-melt adhesive. For example, one of the skin surface side and the outer surface side of the fixed end portion of the fastening member is joined to the diaper body only by the cured reactive urethane hot-melt adhesive, and the other is joined only by the non-reactive hot-melt adhesive. It is preferably joined to the diaper body.

In the present invention, as a mode of joining the diaper main body and the fastening member, for example, the outer joint surfaces of both side edges of the rear portion of the diaper main body and the skin surface side joint surfaces of the fixed ends of the fastening member are joined. A mode in which the skin side joint surfaces of both side edges of the rear portion of the diaper body are joined to the outer side joint surfaces of the fixed end portions of the fastening members, and a member constituting the diaper body (for example, a top sheet , a side sheet, or a back sheet) to sandwich and join the fixed end of the fastening member. In a mode in which the fixed end portion of the fastening member is sandwiched and joined by the members constituting the diaper main body, either the skin surface side or the outer surface side of the fixed end portion of the fastening member and the member constituting the diaper main body are connected to each other. are preferably joined with a reactive urethane hot-melt adhesive.

In the present invention, both side edges of the rear portion of the diaper body have a structure in which at least two nonwoven fabrics are laminated, and the fixed end portion of the fastening member is sandwiched between the at least two nonwoven fabrics to form a reactive urethane tot. It is preferable that they are joined by a cured melt adhesive.

The basis weight of both side edges of at least two laminated nonwoven fabrics is preferably 22 g/m ² or more, more preferably 26 g/m ² or more, still more preferably 28 g/m ² or more, and preferably 50 g/m ² or less. m ² or less is more preferable, and 36 g/m ² or less is even more preferable. Moreover, it is preferable that the nonwoven fabrics forming the side edges are made of polypropylene.

As a mode in which the fixed end portion of the fastening member is sandwiched and joined by members constituting the diaper body, for example, the fixed end portion of the fastening member is sandwiched between a top sheet and a back sheet that constitute both side edge portions of the rear portion of the diaper body. A mode of bonding, side sheets forming both side edges of the rear portion of the diaper main body, and a mode of joining by sandwiching the fixed end portion of the fastening member between the back sheets, a top sheet forming both side edges of the rear portion of the diaper main body. A mode in which the fixed end portion of the fastening member is sandwiched between the side sheets and joined can be mentioned.

In the area where the fastening member and the diaper body are joined (hereinafter sometimes simply referred to as "joint part"), the amount of the cured product of the reactive urethane hot-melt adhesive applied is 5 g/m ² or more. It is preferably 10 g/m ² or more, still more preferably 15 g/m ² or more, preferably 100 g/m ² or less, more preferably 80 g/m ² or less, and even more preferably 50 g/m ² or less. This is because, if the coating amount of the cured product of the reactive urethane hot-melt adhesive is within the above range, the heat-resistant adhesive strength will be good.

The peeling time of the joint between the fastening member and the member of the diaper body joined to the fastening member in an environment of 40° C. is preferably 500 minutes or longer, more preferably 750 minutes or longer, and still more preferably 1000 minutes or longer. be. This is because if the peeling time is 500 minutes or longer, the fastening member can be prevented from coming off from the diaper body even when the wearer uses a heater to heat the joint between the diaper body and the fastening member. A method for measuring the peeling time will be described later.

The adhesive strength of the joint between the member constituting the diaper body and the fastening member is preferably 10 N/50 mm or more, more preferably 11 N/50 mm or more, still more preferably 12 N/50 mm or more, preferably 20 N/50 mm or less, and 19 N/50 mm. The following is more preferable, and 18 N/50 mm or less is even more preferable. This is because if the adhesive strength is within the above range, detachment of the fastening member can be suppressed. The adhesive strength is the adhesive strength after 18 hours or more at 15° C. to 35° C. and humidity of 40% to 70% after application of the hot melt adhesive.

The disposable diaper of the present invention will be described below with reference to the drawings, but the present invention is not limited to the embodiments shown in the drawings.

FIG. 1 is a plan view of a disposable diaper 1 according to an embodiment of the present invention, viewed from the side of a top sheet 10 in an unfolded state. FIG. 2 is a plan view of the disposable diaper 1 in an unfolded state, viewed from the backsheet 20 side. FIG. 3 is a cross-sectional view of the disposable diaper 1 taken along line VV in FIG. FIGS. 1 and 2 show a state in which side seat elastic members 41, waist elastic members 51, and leg elastic members 52, which will be described later, are all stretched. In the figure, the arrow A is defined as the front-rear direction, and the arrow B is defined as the width direction. Also, the direction on the plane formed by arrows A and B is defined as the planar direction. A vertical direction C is the direction perpendicular to the plane defined by the arrows A and B. As shown in FIG.

As shown in FIGS. 1 to 3, the disposable diaper 1 has a liquid-permeable topsheet 10, a liquid-impermeable backsheet 20, and an absorbent core 30 interposed between the sheets 10, 20. It has a diaper body 2 which is a laminate.

The diaper main body 2 has a front portion 2a applied to the abdomen of the wearer, a rear portion 2b applied to the back of the wearer, and a crotch portion 2c connecting the front portion 2a and the rear portion 2b. Hereinafter, the direction in which the front abdominal portion 2a, the crotch portion 2c, and the back portion 2b are connected is referred to as the "front-rear direction", and the direction orthogonal to the front-rear direction and along the surface of the diaper main body 2 is referred to as the "width direction". The diaper main body 2 extends in the front-rear direction from the front portion 2a to the rear portion 2b, and is narrowed in the width direction at the crotch portion 2c located in the middle.

The top sheet 10 is a liquid-permeable sheet arranged on the skin surface side of the diaper body 2 . The top sheet 10 extends in a belt shape from the front portion 2a to the rear portion 2b, and its widthwise dimension is smaller than the widthwise dimension of the outer edge of the diaper body 2. As shown in FIG.

The backsheet 20 is arranged on the outer surface side of the diaper body 2 . The backsheet 20 has substantially the same shape as the diaper body 2 in plan view. That is, the backsheet 20 covers the entire lower surface of the diaper body 2 .

The absorbent core 30 is fixed between the top sheet 10 and the back sheet 20 and has liquid absorption and liquid retention properties. As shown in FIG. 3, the absorbent core 30 is secured between the topsheet 10 and the backsheet 20 with a hot melt adhesive 55. As shown in FIG. Further, as shown in FIG. 1, the absorbent core 30 is formed one size smaller than the outer edge of the diaper body 2 in plan view.

A second fastening member 70 is provided on the outer surface side of the front portion 2 a of the back seat 20 . Although the shape of the second fastening member 70 is rectangular in FIG. 2, it is not limited to this shape.

A pair of side sheets 40 are provided on the upper surface side of the top sheet 10 to prevent lateral leakage of urine. The pair of side sheets 40 extend in the front-rear direction so as to cover the left and right side edges of the diaper body 2 . As shown in FIG. 3, the pair of side sheets 40 are joined to the absorbent core via a hot-melt adhesive 55 on the outer side in the width direction of the top sheet. Also, the pair of side sheets 40 are joined to the skin surface side of the fastening member on the widthwise outer side of the absorbent core. The fastening member and the diaper main body are joined by a cured reactive urethane hot-melt adhesive at the joining portion 80 between the fastening member and the side sheet and/or the joining portion 81 between the fastening member and the back sheet. . The side edges of the side sheets 40 on the inner side in the width direction are not attached to the top surface of the top sheet 10 and can stand up with respect to the top sheet 10 .

A plurality of side-seat elastic members 41 extending in the front-rear direction are arranged on the side edges of the side seats 40 on the inner side in the width direction. The side seat elastic member 41 is attached to the side seat 40 with an adhesive (not shown) in a state of being stretched beyond its natural length. Therefore, the side seat elastic member 41 generates an elastic force for contracting the side seat 40 in the longitudinal direction.

When the disposable diaper is opened, the elastic force of the side sheet elastic member 41 causes the widthwise inner side edge of the side sheet 40 to rise. As a result, a pair of upright weirs are formed on the upper surface of the diaper body 2 to prevent lateral leakage of urine excreted by the wearer.

A plurality of waist elastic members 51 extending in the width direction are provided in the front portion 2a and the rear portion 2b. The waist elastic member 51 is attached between the top sheet 10 and the back sheet 20 with an adhesive (not shown) while being stretched longer than its natural length. Therefore, the waist elastic member 51 generates an elastic force for contracting the front portion 2a and the rear portion 2b in the width direction. When the disposable diaper 1 is put on by the wearer, the front portion 2a and the rear portion 2b can fit around the waist of the wearer due to the contractile force of the waist elastic member 51 .

In addition, a plurality of leg-surrounding elastic members 52 extending in the front-rear direction are provided on both side edges of the crotch portion 2c in the width direction. The leg elastic members 52 are attached between the side seat 40 and the back seat 20 with an adhesive (not shown) while being stretched beyond their natural length. Therefore, the leg-surrounding elastic members 52 generate an elastic force that contracts the side edges of the crotch portion 2c in the longitudinal direction. When the wearer puts on the disposable diaper 1, the contractile force of the leg-surrounding elastic members 52 allows both side edges of the crotch portion 2c to fit the thighs of the wearer.

For the side seat elastic member 41, the waist elastic member 51, and the leg elastic member 52, for example, thread-like elastic members such as polyurethane thread may be used. Also, instead of the thread-like elastic member, a flat plate-like elastic member made of polyurethane, natural rubber, or the like may be used.

The disposable diaper 1 includes a pair of fastening members 60. Each fastening member 60 has a fastening base material 61 and two tongue-like tab portions 62 projecting outward in the width direction from the free end side of the fastening base material 61 . A first fastening member 63 is provided on the skin surface side of each knob portion 62 . The fastening base material 61 is sandwiched between the side sheet 40 and the back sheet 20 at the fixed end 61a on the inner side in the width direction and joined to the main body of the diaper. A hook material (male member) of a hook-and-loop fastener is used for the first fastening member 63 of the present embodiment. On the other hand, as shown in FIG. 2, the outer surface of the front portion 2a of the diaper body 2 is provided with a second fastening member 70 for detachably fastening the first fastening member 63. As shown in FIG. A hook-and-loop fastener loop material (female member) is used for the second fastening member 70 of the present embodiment.

In the disposable diaper 1, the fastening member 60 is joined to the diaper body 2 via a cured reactive urethane hot-melt adhesive at joints 80 and/or joints 81 between the fastening member 60 and the diaper body 2. there is

Each fastening member 60 is joined to a portion of the rear portion 2b of the diaper body 2 that protrudes outward in the width direction from the crotch portion 2c. Specifically, as shown in FIG. 3, the fixed end portion 61a of the fastening base material 61 is joined to the side sheet 40 and the back sheet 20 with a reactive urethane hot-melt adhesive. In the embodiment shown in FIG. 3, since the width of the top sheet 10 is shorter than the width of the back sheet 20, the side sheets 40 are provided on both side edges in the width direction of the back sheet without the top sheet. there is Therefore, the fixed end portion 61a of the fastening base material 61 is sandwiched between the side sheet 40 and the back sheet 20 and joined.

The back sheet 20 is a laminated sheet comprising a liquid-impermeable sheet 20a and a non-woven fabric 20b bonded to the outside of the liquid-impermeable sheet 20a. In the rear portion 2b of the backsheet 20, the width of the liquid-impermeable sheet 20a is narrower than the width of the nonwoven fabric 20b, and the liquid-impermeable sheets 20a are arranged on both side edges of the rear portion 2b of the backsheet 20. It is made of nonwoven fabric 20b. When the side sheets 40 are made of non-woven fabric, both sides of the rear portion of the diaper body have a structure in which two non-woven fabrics, the side sheet and the back sheet, are laminated.

As a mode of applying the reactive urethane hot-melt adhesive, the reactive urethane hot-melt adhesive is applied in stripes at the joint 80 and/or the joint 81 where the diaper body 2 and the fastening member 60 are joined. , spiral coating, etc., and striped coating is preferred.

FIG. 4 shows, for example, a mode in which the reactive urethane hot-melt adhesive 72 is applied in stripes at joints 80 and/or joints 81 where the diaper body 2 and the fastening member 60 are joined. there is

Examples of the mode of applying the reactive urethane hot-melt adhesive 72 to the fastening member 60 include the following modes. In the embodiment of FIG. 5(a), the skin surface side of the fixed end portion 61a of the fastening base material 61 and the outer surface side of the side sheet 40 constituting the main body of the diaper are bonded only by the cured reactive urethane hot-melt adhesive 72. Fixed. Further, the outer surface side of the fixed end portion 61a of the fastening base material 61 and the skin surface side of the back sheet 20 are fixed only by the reactive urethane hot-melt adhesive 72. As shown in FIG.

In the embodiment of FIG. 5(b), the skin surface side of the fixed end portion 61a of the fastening base material 61 and the outer surface side of the side sheet 40 constituting the main body of the diaper are bonded only by the cured reactive urethane hot-melt adhesive 72. The outer surface side of the fixed end portion 61 a of the fastening base material 61 and the skin surface side of the back sheet 20 are fixed only by the non-reactive hot melt adhesive 55 . 5(b), the non-reactive hot-melt adhesive 55 is applied to the skin surface side of the fixed end portion 61a of the fastening base material 61 and the outer surface side of the side sheet 40 constituting the diaper body 2. The outer surface side of the fixed end portion 61 a of the fastening base material 61 and the skin surface side of the back sheet 20 may be fixed only by a cured product of the reactive urethane hot-melt adhesive 72 . In the embodiment of FIG. 5(b) in which a reactive hot-melt adhesive and a non-reactive hot-melt adhesive are used together, the effect of improving the initial adhesive strength is obtained by using the non-reactive hot-melt adhesive.

FIG. 6 is a perspective view showing the state in which the disposable diaper of FIG. 1 is worn. When wearing the disposable diaper 1, first, the disposable diaper 1 is applied to the wearer so that the front part 2a, the crotch part 2c and the rear part 2b face the wearer's abdomen, crotch and back, respectively. Next, both fastening members 60 are pulled along the wearer's side waist to the abdomen side, and the first fastening member 63 is attached to the second fastening member 70 . As a result, as shown in FIG. 6, the front portion 2a and the rear portion 2b of the diaper body 2 are fastened together to form the waist.

A method for manufacturing a disposable diaper according to the present invention comprises: a diaper body having an absorbent core; left and right fastening members respectively joined to both side edge portions of a rear portion of the diaper body and extending outward in the width direction from the diaper body; A first fastening member provided on the skin side of each of the left and right fastening members, and a second fastening member provided on the outer surface side of the front portion of the diaper body, to which the first fastening member is detachably fastened. A method of manufacturing a disposable diaper having a binding member, characterized in that both side edges in the width direction of the rear portion of the diaper body and the fastening member are joined using a reactive urethane hot-melt adhesive. .

The reactive urethane hot-melt adhesive may be applied to either the diaper main body or the fastening member, as long as it can bond both side edges in the width direction of the rear portion of the diaper main body to the fastening member. It may be appropriately determined based on the configuration of the diaper main body, the bonding state between the fastening member and the diaper main body, and the like.

For example, the outer surface side of the side sheet and the skin surface side of the fastening member constituting the main body of the diaper are joined with a cured product of a reactive urethane hot-melt adhesive, and the skin surface side of the back sheet and the fastening member constituting the main body of the diaper are joined. The method of manufacturing a disposable diaper (embodiment of FIG. 5(b)) fixed with a non-reactive hot-melt adhesive on the outer surface side preferably includes the following steps.

a) A step of applying a non-reactive hot-melt adhesive to the skin side of the backsheet. The non-reactive hot-melt adhesive is preferably applied to substantially the entire surface of the backsheet on the skin side. The absorbent core 30 is joined to the backsheet 20 by this non-reactive hot melt adhesive 55 . The non-reactive hot-melt adhesive 55 applied to the widthwise side edges of the backsheet 20 where the absorbent core 30 is not arranged is applied to the skin surface side of the backsheet 20 and the outer surface side of the fastening member 60, and It is used to join the skin surface side of the back sheet 20 and the outer surface side of the side sheet 40 . The non-reactive hot melt adhesive 55 is preferably applied by a contact or non-contact applicator. It can also be applied in stripes or spirals.

b) A step of laminating the absorbent core 30 on the back sheet 20 coated with the non-reactive hot melt adhesive 55 . At the time of lamination, it is preferable to position the back sheet 20 so that the widthwise centerline of the absorbent core 30 substantially coincides with the widthwise centerline of the absorbent core 30 .

c) A step of laminating the top sheet 10 and the side sheets 40 .
The side sheets 40 are joined to both width direction ends of the skin side of the top sheet 10 or the side sheets 40 by adhesive or heat welding. , to prepare a laminate in which the side sheets 40 are joined to both widthwise end portions of the top sheet 10 on the skin surface side. Instead of laminating the top sheet 10 and the side sheets 40 in advance, the side sheets 40 and the top sheet 10 may be sequentially laminated on the back sheet 20 on which the absorbent core is arranged.

In addition, it is preferable to apply a non-reactive hot-melt adhesive 55 to both longitudinal (front-rear) end portions of the inner region in the width direction of the side sheet 40 . The widthwise inner portion of the side sheet 40 is joined to the top sheet 10 with a non-reactive hot-melt adhesive 55 at both ends in the longitudinal direction (front-to-rear direction). It is preferable not to apply the non-reactive hot-melt adhesive 55 to the portion corresponding to the upright portion of the widthwise inner region of the side sheet 40 . The non-reactive hot melt adhesive 55 is preferably applied by a contact or non-contact applicator. Also, the non-reactive hot-melt adhesive 55 is preferably applied in a striped or spiral pattern.

d) A step of applying a reactive urethane hot-melt adhesive 72 to the skin side of the fastening member 60 (the fixed end portion 61a of the fastening base material 61). The reactive urethane hot-melt adhesive 72 is preferably applied by a contact-type or non-contact-type applicator, more preferably a contact-type applicator. The reactive urethane hot-melt adhesive is preferably applied in a curtain-like, omega-like, stripe-like or spiral-like manner, more preferably in a stripe-like manner.

e) A step of laminating the fastening members 60 on the laminate of the top sheet 10 and the side sheets 40 . A reactive urethane hot-melt adhesive 72 applied to the skin surface side of the fastening member 60 joins the skin surface side of the fastening member 60 to both width direction ends of the outer surface side of the side sheet 40 , thereby bonding the outer surface of the side sheet 40 . A laminated body (a laminated body of the top sheet 10, the side sheets 40, and the fastening members 60) is prepared by joining the fastening members 60 to both ends in the width direction of the side.

f) A step of applying a non-reactive hot-melt adhesive 55 to the outer surface side of the laminate of the top sheet 10 , the side sheets 40 and the fastening members 60 . The non-reactive hot-melt adhesive 55 is preferably applied to the outer surfaces of the topsheet 10 and sidesheets 40 . This non-reactive hot melt adhesive 55 joins the top sheet 10 and side sheets 40 to the absorbent core 30 and back sheet 20 . The non-reactive hot melt adhesive 55 is preferably applied by a contact or non-contact applicator. Also, the non-reactive hot-melt adhesive 55 is preferably applied in a striped or spiral pattern.

g) A step of laminating the laminate of the top sheet 20, the side sheets 40, and the fastening members 60, and the back sheet 20 on which the absorbent core 30 is arranged, to produce the diaper main body. That is, the fastening member 60 and the diaper main body 2 are joined by sandwiching the fixed end portion 61 a of the fastening base material 61 between the side sheet 40 and the back sheet 20 . It is preferable that the joining portion is subjected to pressure treatment with a roller or the like.

f) Disposable diapers manufactured using a reactive urethane hot-melt adhesive are preferably cured at a humidity of 40% to 90% and 15 to 30°C for about 120 hours. Curing does not require any special treatment and is preferably carried out by being stored in a warehouse as a final product. Curing under the above conditions promotes the moisture curing reaction of the reactive urethane hot-melt adhesive to cure it. As a result, a three-dimensional crosslinked structure is formed, and heat-resistant adhesive strength is exhibited.

Next, the process of applying the hot-melt adhesive to the fastening member 60 will be described with reference to FIGS. 7 to 10. FIG. In the configuration shown in FIG. 7 and the like, the case where the configuration shown in FIG. 5B is adopted as the configuration of the fastening member 60 will be described. In addition, in the configuration shown in FIG. 7 and the like, the hot-melt adhesive for adhering the fastening member 60 is applied to the skin side of the fastening member 60, but the hot-melt adhesive is applied to the outer surface side of the side sheet 40. You may do so.

Here, the fastening base material continuum 146 shown in FIG. 7 is a strip-shaped material in which the left and right fastening base materials 61 are continuously linked in the longitudinal direction Y, and the central portion of this fastening base material continuum 146 is assumed to be The left and right fastening base materials 61 are produced by dividing into two left and right continuous partial bodies along a wavy cut line 147 indicated by a line, and cutting each partial continuous body into predetermined dimensions. At the central portion of the fastening base material continuous body 146 , a first material for forming the first fastening member 63 is continuously arranged in the longitudinal direction Y before being cut into the fastening base material 61 . One fastening member continuous body 148 is joined by a joining means such as an adhesive. Then, in a state in which the first fastening member continuous body 148 is joined, the fastening base continuous body 146 is cut into the fastening base material 61, whereby fastening is performed in a state in which the first fastening member 63 is previously joined. A substrate 61 is produced.

Application of the hot-melt adhesive to the fastening base material 61 is performed on the fastening base continuous body 146 before the fastening base material 61 is separated. As a modification, hot melt and adhesive may be applied after the fastening base material continuous body 146 is divided into left and right partial continuous bodies by the cut line 147 .

Application of the reactive urethane hot-melt adhesive 72 to the fastening base material continuous body 146 is preferably performed using a coater head 151 as shown in FIG. The coater head 151 is arranged in a state in which an adhesive discharge part 152, which will be described later and discharges the reactive urethane hot-melt adhesive 72, is in contact with the coating surface (here, the surface of the fastening base material continuous body 146), or It is a contact-type adhesive applicator that is arranged close to each other with a small gap. In addition, in the configuration shown in FIG. 8, it is assumed that individual coater heads 151 are arranged in two hot-melt adhesive application regions on both sides of the fastening base material continuous body 146 in the lateral direction X. A single coater head 151 may be used to apply the hot melt adhesive. As a modification, a non-contact adhesive coating device such as a spiral coating device in which the adhesive discharge part 152 for discharging the hot melt adhesive is arranged with a gap from the coating surface may be employed.

This coater head 151, as shown in FIGS. 9 and 10, has an adhesive discharge section 152 for discharging the reactive urethane hot-melt adhesive. The adhesive discharge part 152 is arranged at a position corresponding to the adhesive application area. Then, the coater head 151 is arranged so that the adhesive discharge part 152 faces the position where the adhesive application area of the fastening base material continuous body 146 is to be formed, and the reactive urethane hot-melt adhesive is applied from the adhesive discharge part 152 . The fastening base material continuous body 146 is transported in the transport direction parallel to the longitudinal direction Y while discharging the reactive urethane hot melt adhesive along the vertical direction Y at a predetermined position of the fastening base material continuous body 146. Applied in strips.

The fastening base material continuous body 146 to which the reactive urethane hot-melt adhesive is applied is cut into fastening base materials 61 . Then, the portion (fixed end portion) of the cut fastening base material 61 on the inner side in the lateral direction X is joined to the diaper body 2 so as to be sandwiched between members constituting the diaper body 2 .

Next, a specific configuration example of the coater head 151 will be described. Various configurations can be adopted as the configuration of the coater head 151, and the configuration is not limited to the configuration described here. The coater head 151 comprises first and second head portions 156, 157 and a shim 158, as shown in FIGS. The first and second head portions 156 and 157 are fixed while facing each other with a shim 158 interposed therebetween.

The shim 158 has a substantially plate-like shape, and the adhesive discharge portion 152 is formed thereon. One or more slits 159 are formed in the adhesive discharge portion 152 by lowering part of the lower edge of the shim 158 in a substantially comb-teeth shape.

A portion of the shim 158 facing the adhesive discharge portion 152 on the surface of the first head portion 156 facing the shim 158 is provided with an adhesive for supplying, for example, a reactive urethane hot-melt adhesive to the adhesive discharge portion 152 . An agent supply recess 156a is provided. The adhesive is supplied to the adhesive supply recess 156a through the supply path 156b. Adhesive for supplying a reactive hot-melt adhesive to the adhesive discharging portion 152 is applied to the portion of the shim 158 facing the adhesive discharging portion 152 on the surface of the second head portion 157 facing the shim 158 . Supply recesses 157a are provided respectively. The adhesive is supplied to the adhesive supply recess 157a through the supply path 157b.

In the configuration shown in FIG. 10 and the like, the two adhesive supply recesses 156a and 157a for supplying the adhesive to the adhesive discharge section 152 are formed separately in the two head sections 156 and 157. Alternatively, the two adhesive supply recesses 156a and 157a may be formed in one of the head portions 156 and 157 and the other head portion 156 and 157 may be omitted.

Hereinafter, the present invention will be described in detail with reference to examples, but the present invention is not limited to the following examples, and any modifications and embodiments that do not depart from the scope of the present invention can be made within the scope of the present invention. Included in scope.

[Evaluation method]
(melt viscosity)
The viscosity was measured at 120° C. using a Brookfield viscometer in accordance with JIS-K6662.

(open time)
A 15 mm wide spunbond nonwoven fabric (20 g/m ² ) is coated with 50 g/m ² of reactive urethane hot melt adhesive at 180°C. Next, another spunbond nonwoven fabric (20 g/m ² ) is placed within 2 seconds after coating and pressed under a load of 2 kg. After standing for a certain period of time, a 180° peeling test was performed at a peeling speed of 300 mm/min, and the time elapsed from the time when the adhesive was applied to the time when 80% or more of the nonwoven fabric in the coated area was destroyed. Open time.

(Adhesion test)
A disposable diaper was manufactured by bonding both side edges in the width direction of the rear portion of the diaper body to the fastening member with a reactive urethane hot-melt adhesive. The joint surface on the outer surface side of the side sheet and the joint surface on the skin surface side of the fastening base material are joined with a cured product of a reactive urethane hot-melt adhesive. Using the disposable diaper after the lapse of a predetermined period of time after production, a 100 mm long test piece extending from the joint between the side sheet and the fastening member to the fastening member extending outward from the side sheet was prepared with a width of 50 mm (Fig. 11, specimen 90). A fastening member was attached to the upper chuck of a tensile tester (Tensilon universal tester RTG-1210, manufactured by A&D), and a side sheet was attached to the lower chuck so that the longitudinal direction of the test piece was the tensile direction. Next, the test piece was pulled in a direction of 180 degrees at a speed of 300 mm/min, the stress was measured until the fastening member was separated from the diaper body, and the maximum value of the stress was taken as the adhesive strength. Table 1 shows the results. In addition, the adhesive force was tested for each of the left and right fastening members of five disposable diapers, and the average value was shown.

As can be seen from the results in Table 1, the adhesive strength of the joints using the reactive urethane hot-melt adhesive increased over time. This result indicates that the reactive urethane hot-melt adhesive exhibits adhesive strength due to moisture curing reaction.

(Heat-resistant adhesion test)
Using a disposable diaper that has passed at room temperature for 5 days or more after production, the diaper body is positioned widthwise outward from the diaper body via a portion where the fastening member and the diaper body overlap from the diaper body positioned widthwise inward from the fastening member. A 100 mm long test piece with a width of 25 mm was produced, including the region extending to the fastening member. Next, after attaching a weight of 500 g to the fastening member, the diaper was lifted with the main body side up in an atmosphere of 40° C., and the time until the fastening member separated from the main body of the diaper and dropped was measured. Table 2 shows the results. In addition, the outer joint surface of the side sheet and the skin surface joint surface of the fastening base material are joined with a cured reactive urethane hot-melt adhesive. In addition, the peeling time was shown as an average value after testing each of the left and right fastening members of the four disposable diapers.

The peel time for joints using reactive hot melt adhesives is greater than 1000 minutes and the peel time for joints using non-reactive hot melt adhesives is 73 minutes. From this result, it can be seen that the joints using the reactive hot-melt adhesive are excellent in heat-resistant adhesiveness.

In the adhesive force test and the heat resistant adhesive force test, hot melt adhesives having the following properties were used.
[Reactive Urethane Hot Melt Adhesive A]
A) Melt viscosity 13,000 to 20,000 mPa s/120°C
B) Softening point 100-130°C
C) The number average molecular weight of the urethane prepolymer is 1000 to 10000
D) The isocyanate group content (NCO%) in the urethane prepolymer is 1.7 to 5.0
E) The ratio of the total isocyanate groups of the polyisocyanate to the total hydroxyl groups of the polyol (B) (hereinafter referred to as the NCO/OH ratio) is 1.1 to 5.0.
[Non-reactive hot melt adhesive B]
Non-reactive hot melt adhesive manufactured by MORESCO (SBS block copolymer, melt viscosity 5200 mPa s/160°C, softening point 102°C)

1: disposable diaper, 2: diaper main body, 2a: front part, 2b: rear back part, 2c: crotch part, 10: top sheet, 20: back sheet, 30: absorbent core, 40: side sheet, 41: for side sheet Elastic member 51: Waist elastic member 52: Leg elastic member 55: Hot melt adhesive 60: Fastening member 61: Fastening base material 62: Knob portion 63: First fastening member 70: Second fastening member, 72: Reactive urethane hot melt adhesive, 80: Joint, 81: Joint, 90: Test piece

Claims (8)

a diaper body having an absorbent core;
Left and right fastening members respectively joined to both side edge portions of the rear portion of the diaper body and extending outward in the width direction from the diaper body;
a first fastening member provided on the skin surface side of each of the left and right fastening members;
a second fastening member provided on the outer surface side of the front portion of the diaper main body and to which the first fastening member is detachably fastened;
One of the skin surface side and the outer surface side of the fixed end portion of the fastening member is joined to the diaper main body only by a cured reactive urethane hot-melt adhesive, and the other is joined to the diaper main body only by a non-reactive hot-melt adhesive. A disposable diaper characterized by being joined . Both side edges of the rear part of the diaper body have a structure with a weight per unit area of 22 g/m ² to 50 g/m ² in which at least two polypropylene nonwoven fabrics are laminated, and the fixed end portion of the fastening member is formed of the at least two sheets. 2. The disposable diaper according to claim 1 , wherein the disposable diaper is sandwiched between two non-woven fabrics and bonded by a cured reactive urethane hot -melt adhesive and a non-reactive hot-melt adhesive . 3. The disposable diaper according to claim 1, wherein the fixed end portion of the fastening member is made of polypropylene spunbond nonwoven fabric having a basis weight of 45 g/m ² to 80 g/m ² . The diaper main body has a back sheet, the absorbent core arranged on the skin surface side of the back sheet, and a top sheet arranged on the skin surface side of the absorbent core, and fixed ends of the fastening members are attached to the top sheet. 4. The disposable diaper according to any one of claims 1 to 3 , wherein the disposable diaper is sandwiched between the back sheet and the cured product of the reactive urethane hot-melt adhesive and the non-reactive hot-melt adhesive . The diaper body includes a back sheet, the absorbent core provided on the skin side of the back sheet, a top sheet provided on the skin side of the absorbent core, and side sheets joined to both sides in the width direction of the top sheet. wherein the fixed end portion of the fastening member is sandwiched between the side sheet and the back sheet and is joined by a cured reactive urethane hot-melt adhesive and a non-reactive hot-melt adhesive. 4. The disposable diaper according to any one of 1 to 3 . 6. The amount of the cured reactive urethane hot-melt adhesive applied to the joint between the material forming the main body of the diaper and the fastening member is 5 g/m ² to 100 g/m ² , according to any one of claims 1 to 5 . The disposable diaper described in . The disposable diaper according to any one of claims 1 to 6, wherein the reactive urethane hot-melt adhesive has a melt viscosity (120°C) of 2,000 mPa·s or more and 20,000 mPa·s or less . 8. The disposable according to any one of claims 1 to 7, wherein a peeling time of the joint between the fastening member and the member of the diaper body joined to the fastening member in an environment of 40°C is 500 minutes or longer. diaper .

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