JP2019165827A - Disposable diaper - Google Patents

Abstract

To provide a disposable diaper capable of restraining a fastening portion from detaching from the diaper body even when the wearer uses a heating appliance.SOLUTION: A disposable diaper 1 is characterized in that: a diaper body 2 and a fastening member 60 are secured by a cured product 80 of a reactivity urethane hotmelt adhesive; the reactivity urethane hotmelt adhesive is obtained by reacting a polyol composition comprising a polyester polyol having a number-average molecular weight of 500-10000 with a polyisocyanate composition comprising diisocyanate but not comprising isocyanurate-modified products of diisocyanate; the percentage content of the isocyanate group in the reactivity urethane hotmelt adhesive is 0.8 mass%-5 mass%; and the elasticity modulus of the cured product of the reactivity urethane hotmelt adhesive is 0.1 MPa-50 MPa.SELECTED DRAWING: Figure 3

Description

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

  A disposable diaper having a fastening means has been proposed. In a disposable diaper having such fastening means, a load is easily applied to the joint portion between the fastening base material and the diaper body constituting the fastening means, and the joint portion may be peeled off or damaged. 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, a diaper having improved joint strength at the joint has been proposed. For example, in Patent Document 1, a fastening base material joint 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. A disposable diaper has been proposed (see Patent Document 1 (claim 2, paragraph 0006)).

  In addition, when a surface fastener is used as the fastening means, it has also been proposed to improve the joint strength of the joint portion between the fastening base material and the surface fastener. For example, Patent Document 2 discloses a polyurethane prepolymer obtained by polyaddition of at least one polyol to at least one diisocyanate trimerized as isocyanurate, a reaction product of diisocyanate and water, Hygiene having a fixing element in the form of a woven mesh bonded by a moisture-crosslinkable hot melt adhesive comprising a pre-polymer free NCO group content of 1 to 25% by weight Articles have been proposed (see Patent Document 2 (claim 12, paragraphs 0004 and 0005)).

JP 2011-097975 A JP-T-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. Therefore, when the softening point of the adhesive used for joining the fastening member and the diaper main body is low, the joining strength is lowered, and the fastening member may be detached from the diaper main body. This invention is made | formed in view of the said situation, and it aims at providing the disposable diaper which can suppress detachment | leave from the diaper main body of a fastening member, even when a wearer uses a heater.

  The disposable diaper of the present invention includes a diaper main body having an absorbent core, left and right fastening members respectively joined to both side edges of a rear portion of the diaper main body, and extending laterally outward from the diaper main body. A first fastening portion provided on the skin surface side of the fastening member, and a second fastening portion provided on the outer surface side of the front portion of the diaper main body, wherein the first fastening portion is detachably fastened. The diaper main body and the fastening member are fixed by a cured product of a reactive urethane hot melt adhesive. The reactive urethane hot melt adhesive contains a polyurethane prepolymer having an isocyanate group at the end of the molecular chain, and the polyurethane prepolymer is obtained by reacting a polyol composition and a polyisocyanate composition. The polyol composition contains a polyester polyol having a number average molecular weight of 500 to 10,000, the polyisocyanate composition contains a diisocyanate, and does not contain an isocyanurate-modified product of diisocyanate. JIS K 1603- The content of isocyanate groups before curing of the reactive urethane hot melt adhesive obtained by method A of 1 is 0.8% by mass to 5.0% by mass, and the cured product of the reactive urethane hot melt adhesive. The elastic modulus of the material is 0.1 MPa to 50 MPa. And features.

  In the disposable diaper of the present invention, the diaper main body and the fastening member are fixed by a cured product of a reactive urethane hot melt adhesive. The reactive urethane hot melt adhesive reacts with moisture in the air to form a three-dimensional crosslink and cure. That is, the cured product of the reactive urethane hot melt adhesive is very excellent in heat resistance. Therefore, the disposable diaper of the present invention can suppress detachment of the fastening member from the diaper body even when the wearer uses the heating appliance and the joint between the diaper body and the fastening member is warmed.

  The disposable diaper of the present invention can suppress detachment of the fastening member from the diaper main body even when the wearer uses a heater.

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 seat | sheet side. The typical sectional view of the VV line of Drawing 1. The perspective view which shows the state with which the disposable diaper of FIG. 1 was worn.

  The disposable diaper of this invention has a fastening means. The fastening means is provided on the outer surface side of the fastening member joined to the diaper main body, the first fastening portion provided on the skin surface side of the fastening member, and the front side portion of the diaper main body, The fastening part is composed of a second fastening part that is detachably fastened. And the said fastening member is being fixed by the hardened | cured material of the said diaper main body and a reactive urethane hot-melt-adhesive.

  The reactive urethane hot melt adhesive is a moisture curable adhesive, and reacts with moisture in the air to form a three-dimensional crosslink and cure. That is, the cured product of the reactive urethane hot melt adhesive is very excellent in heat resistance. Therefore, the disposable diaper of the present invention can suppress detachment of the fastening member from the diaper body even when the wearer uses the heating appliance and the joint between the diaper body and the fastening member is warmed. In addition, the reactive urethane hot melt adhesive can be applied in a molten state like a conventional hot melt, and can fix a non-adhesive by cooling and solidifying. Therefore, if a reactive urethane hot melt adhesive is used, conventional manufacturing equipment can be used, and a decrease in productivity can be suppressed.

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

  The polyurethane prepolymer is obtained by reacting a polyol composition with a polyisocyanate composition.

  The polyol composition contains a polyester polyol having a number average molecular weight of 500 to 10,000. The number average molecular weight of the polyester polyol is preferably 500 or more, more preferably 1000 or more, still more preferably 2000 or more, preferably 10,000 or less, more preferably 8000 or less, and still more preferably 5000 or less. When the number average molecular weight of the polyester polyol is less than 500, the elastic modulus of the cured product becomes too high, and the texture of the adhesive decreases, and when it exceeds 10,000, the melt viscosity is high and coating becomes difficult. The number average molecular weight of the polyol component may be measured by gel permeation chromatography (GPC) using polystyrene as a standard substance, tetrahydrofuran as an eluent, and an organic solvent GPC column as a column.

  The polyester polyol is preferably obtained by reacting a diol having two hydroxy groups in the molecule with a dicarboxylic acid having two carboxy groups in the molecule. The polyester polyol preferably has two hydroxy groups in the molecule.

  Examples of the diol include alkanediol and alkanediol polymer. The alkanediol has preferably 2 or more carbon atoms, preferably 10 or less, and more preferably 5 or less. Examples of the alkanediol include ethylene glycol, propylene glycol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol, 1,9 -Alkylene diols such as nonanediol and 1,10-decanediol; alkanediols having a branched chain such as 1,3-butanediol and neopentylglycol; alkanediols having an alicyclic structure such as 1,4-cyclohexanedimethanol Is mentioned. Examples of the alkanediol polymer include diethylene glycol and dipropylene glycol. The said diol may be used independently and may use 2 or more types together.

  As said dicarboxylic acid, alkylene dicarboxylic acid and aryl dicarboxylic acid are preferable, and linear alkylene dicarboxylic acid is more preferable. The alkylene group of the alkylene dicarboxylic acid preferably has 2 or more carbon atoms, preferably 10 or less, and more preferably 5 or less. Examples of the alkylene dicarboxylic acid include propanedioic acid (malonic acid), butanedioic acid (succinic acid), pentanedioic acid (glutaric acid), hexanedioic acid (adipic acid), heptanedioic acid (pimelic acid), and octanedioic acid. (Suberic acid), nonanedioic acid (azelaic acid), linear alkylenedicarboxylic acid such as decanedioic acid (sebacic acid). Examples of the aryl dicarboxylic acid include phthalic acid, isophthalic acid, and terephthalic acid. The said dicarboxylic acid may be used independently and may use 2 or more types together.

  The polyester polyol preferably contains a diol having an alkylene structure having 2 to 5 carbon atoms or a dicarboxylic acid having an alkylene group having 2 to 5 carbon atoms as a constituent component. By using such a polyester polyol, appropriate flexibility and crystallinity can be imparted.

  The polyol composition may contain a plurality of polyester polyols having a number average molecular weight of 500 to 10,000. The polyester polyol having a number average molecular weight of 500 to 10,000 is, for example, a polyester containing an alkanediol having 2 to 5 carbon atoms and an alkylene dicarboxylic acid having 2 to 5 carbon atoms in an alkylene group as constituent components. Polyol: a polyester polyol containing a polymer of an alkanediol having 2 to 5 carbon atoms and an aryl dicarboxylic acid having an aryl group having 6 to 10 carbon atoms as a constituent component; an alkane having 2 to 5 carbon atoms as a constituent component And a polyester polyol containing a diol, an alkylene dicarboxylic acid having 2 to 5 carbon atoms in the alkylene group, and an aryl dicarboxylic acid having 6 to 10 carbon atoms in the aryl group.

  The polyol composition may contain a polyol component other than the polyester polyol. In this case, the content of the polyester polyol in the polyol composition is preferably 50% by mass or more, more preferably 70% by mass or more, and further preferably 90% by mass or more. Moreover, it is also preferable that the said polyol composition contains only the polyester polyol whose said number average molecular weight is 500-10000. In particular, it is also preferable that the polyol composition contains only a compound having two hydroxy groups (diol compound) in the molecule.

  Examples of other polyol components contained in the polyol composition include polyether polyols, polyacrylic polyols, polyolefin polyols, polybutadiene polyols, polycarbonate polyols, polycaprolactone polyols, and polyester polyols having a number average molecular weight of less than 500 or more than 10,000. Can be mentioned.

  The polyisocyanate composition contains a diisocyanate and does not contain an isocyanurate-modified product of diisocyanate.

  The diisocyanate has two isocyanate groups in the molecule. The diisocyanate is preferably at least one selected from the group consisting of diphenylmethane diisocyanate, dimethyldiphenylmethane diisocyanate, dicyclohexylmethane diisocyanate, tolylene diisocyanate, hexamethylene diisocyanate, xylylene diisocyanate, phenylene diisocyanate, and isophorone diisocyanate. Among these, diphenylmethane diisocyanate is more preferable from the viewpoint of reactivity and economy. The said diisocyanate may be used independently and may use 2 or more types together.

  The polyisocyanate composition does not contain an isocyanurate-modified product of diisocyanate. The polyisocyanate composition preferably does not contain a diisocyanate burette-modified product or a diisocyanate allophanate product.

  The polyisocyanate composition may contain a polyisocyanate compound having three or more isocyanate groups in the molecule. In this case, the content of diisocyanate in the polyisocyanate composition is preferably 50% by mass or more, more preferably 70% by mass or more, and further preferably 90% by mass or more. The polyisocyanate composition preferably contains only diisocyanate.

  Examples of the polyisocyanate compound having three or more isocyanate groups in the molecule include 1,3,6-triisocyanate hexane, 1,3,5-triisocyanate cyclohexane, 1,3,5-triisocyanate methylbenzene, And triisocyanates such as phenylmethane-4,4 ′, 4 ″ -triisocyanate; tetraisocyanates such as 4,4′-diphenylmethane-2,2 ′, 5,5′-tetraisocyanate; and the like.

  A conventionally known method may be adopted as a method for producing a polyurethane prepolymer by reacting the polyol composition and the polyisocyanate composition.

  The molar ratio of the hydroxyl group in the polyol composition to the isocyanate group in the polyisocyanate composition (isocyanate group / hydroxy group) when synthesizing the polyurethane prepolymer is preferably 1.2 or more, more preferably 1. 4 or more, more preferably 1.6 or more, preferably 3.0 or less, more preferably 2.5 or less, still more preferably 2.0 or less. If the molar ratio is 1.2 or more, high molecular weight and an increase in melt viscosity are suppressed, and synthesis is facilitated. If 3.0 or less, foaming during moisture curing can be suppressed.

  The number average molecular weight of the polyurethane prepolymer is preferably 500 or more, more preferably 1000 or more, further preferably 2000 or more, preferably 20000 or less, more preferably 8000 or less, and still more preferably 6000 or less. If the number average molecular weight of the polyurethane prepolymer is 500 or more, practical initial adhesiveness is easily obtained immediately after adhesion, and if it is 20000 or less, it is easy to apply at the time of melting. The number average molecular weight of the polyurethane prepolymer may be measured by gel permeation chromatography (GPC) using polystyrene as a standard substance, tetrahydrofuran as an eluent, and an organic GPC column as a column.

  The content of isocyanate groups in the polyurethane prepolymer is preferably 0.8% by mass or more, more preferably 1.0% by mass or more, still more preferably 1.5% by mass or more, and 5.0% by mass or less. More preferably, it is 4.0 mass% or less, More preferably, it is 3.0 mass% or less. If the isocyanate group content is 0.8% by mass or more, the heat resistance of the cured product after moisture curing is further improved, and if it is 5.0% by mass or less, foaming during moisture curing can be suppressed. The content of the isocyanate group is determined by method A of JIS K 1603-1 (2007).

In addition to the polyurethane prepolymer, the reactive urethane hot melt adhesive may be polyurethane, ethylene copolymer, propylene copolymer, vinyl chloride copolymer, acrylic copolymer, styrene, if necessary. -Thermoplastic polymers such as conjugated gen block copolymer, rosin resin, rosin ester resin, hydrogenated rosin ester resin, terpene resin, terpene phenol resin, hydrogenated terpene resin, petroleum resin, hydrogenated petroleum resin, coumarone resin, ketone Resins, styrene resins, modified styrene resins, xylene resins, epoxy resins and other tackifying resins, dibutyltin dilaurate, dibutyltin dioctate, dimethylcyclohexylamine, dimethylbenzylamine, trioctylamine and other catalysts, pigments, antioxidants, ultraviolet rays Absorber, surfactant, flame retardant It may contain such fillers.
The content of the polyurethane prepolymer in the reactive urethane hot melt adhesive is preferably 50% by mass or more, more preferably 70% by mass or more, and further preferably 90% by mass or more.

  The isocyanate group content before curing of the reactive urethane hot melt adhesive is preferably 0.8% by mass or more, more preferably 1.0% by mass or more, and further preferably 1.5% by mass or more. 5.0 mass% or less is preferable, More preferably, it is 4.0 mass% or less, More preferably, it is 3.0 mass% or less. If the isocyanate group content is less than 0.8% by mass, sufficient heat resistance may not be obtained after moisture curing, and if it exceeds 5.0% by mass, foaming tends to occur during moisture curing. The content of the isocyanate group is determined by method A of JIS K 1603-1 (2007).

  The elastic modulus of the cured product of the reactive urethane hot melt adhesive is preferably 0.1 MPa or more, more preferably 0.3 MPa or more, still more preferably 0.5 MPa or more, and preferably 50 MPa or less, more preferably 20 MPa. Hereinafter, it is more preferably 10 MPa or less. If the elastic modulus of the cured product is less than 0.1 MPa, sufficient adhesiveness may not be obtained, and if it exceeds 50 MPa, the texture of the adhesive product is lowered.

(Disposable diapers)
Next, the structure of the disposable diaper will be described. The disposable diaper includes a diaper main body, left and right fastening members that are joined to both side edges of the rear portion of the diaper main body and extend laterally outward from the diaper main body, and skin surfaces of the left and right fastening members. A first fastening part provided on each side, and a second fastening part provided on the outer surface side of the front part of the diaper main body and detachably fastened to the first fastening part.

  The diaper body has an absorbent core that absorbs liquid and is applied to the wearer. The diaper main body has a front part, a crotch part, and a rear part. The front part is applied to the wearer's belly side, the rear part is applied to the wearer's back side, and the crotch part is applied to the inseam of the wearer. In addition, in the said diaper main body and a fastening member, the side which opposes a wearer's skin at the time of wear is a skin side, and the back surface of this skin side is an outer surface side.

  The diaper body has an absorbent core that absorbs liquid. The absorption core absorbs and retains excretion fluid (for example, urine and water contained in feces) excreted by the wearer. Specifically, the absorbent core contains water absorbent resin powder and / or water absorbent fibers. As the water-absorbent resin powder, those conventionally used in absorbent articles can be used. Examples of the water-absorbing fibers include pulp fibers, cellulose fibers, rayon, and acetate fibers. The shape of the absorbent core in plan view is not particularly limited, and examples thereof include a rectangular shape, an hourglass shape, a gourd shape, and a battledore shape.

  The diaper main body preferably includes a top sheet disposed on the skin surface side of the absorbent core and a back sheet disposed on the outer surface side of the absorbent core.

  The said top sheet has liquid permeability, and permeate | transmits the excretion liquid from a wearer rapidly. Examples of the top sheet include a nonwoven fabric formed of hydrophilic fibers. Examples of the hydrophilic fiber 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 airlaid nonwoven fabric.

  The back sheet may be either a liquid permeable sheet or a liquid impermeable sheet, but is preferably a liquid impermeable sheet. If it is a liquid-impervious sheet, it can prevent that the excretion liquid which reached | attained the back sheet oozes out to the outer surface side of a diaper main body. As the liquid-impervious sheet, a water-repellent or liquid-impervious nonwoven fabric (for example, spunbond nonwoven fabric, melt blown nonwoven fabric, SMMS (spunbond) formed of hydrophobic fibers (for example, polypropylene, polyethylene, polyester, polyamide). (Melt blow, melt blow, spun bond) non-woven fabric) and water-repellent or liquid-impervious plastic films can be used. Moreover, you may use the laminated sheet comprised from the liquid impervious sheet and the nonwoven fabric bonded together on the outer surface side of this liquid impervious sheet as the said back sheet.

  The diaper main body may have left and right side sheets on the skin surface side. The left and right side sheets are provided along the vertical direction (front-rear direction) with a gap in the horizontal direction (width direction) on the skin surface side of the top sheet, and stand up in the direction away from the top sheet (skin surface side) Configured as possible. An elastic member extended in the front-rear direction is disposed at the front ends (upper ends when standing) of the left and right side seats, and the side seat stands on the skin surface side of the wearer by the contraction force of the elastic members. A solid gather is constituted by the side seats and the elastic member, and side leakage of urine and feces excreted by the solid gather is prevented. As the side sheet, a water-repellent or liquid-impervious nonwoven fabric formed of hydrophobic fibers can be used.

  The diaper main body is provided with a second fastening part on the outer surface side of the front part. The second fastening portion can be detachably fastened to a first fastening portion provided on a fastening member described later. What is necessary is just to adjust suitably the position and range which provide the said 2nd fastening part according to the shape of the fastening member mentioned later, and the position of a 1st fastening part.

  The disposable diaper of this invention has a fastening member. The material of the said fastening member is not specifically limited, What is necessary is just to have the intensity | strength which can fasten a disposable diaper at the time of wear. Examples of the material of the fastening member include a nonwoven fabric and a resin film.

  The left and right fastening members are joined to both side edges of the rear portion of the diaper main body, and are formed to extend outward in the lateral direction from the diaper main body. Further, the left and right fastening members are provided with first fastening portions on the skin surface side. Fastening means is constituted by the pair of left and right fastening members, the first fastening portion provided on the fastening members, and the second fastening portion provided on the diaper body. When the disposable diaper is worn, the fastening means is used to fasten the front part and the rear part of the diaper main body to form a waistline.

  The first fastening part and the second fastening part are not particularly limited as long as they can be detachably fastened. As a combination of the first fastening part and the second fastening part, for example, a mode in which the first fastening part and the second fastening part constitute a hook-and-loop fastener; the first fastening part is an adhesive tape, A mode in which the second fastening part is an adhesive sheet to which the adhesive tape can be detachably attached is exemplified. In addition, when employ | adopting a hook_and_loop | surface fastener, it is preferable to arrange | position a hook material to a 1st fastening part and to arrange | position a loop material to a 2nd fastening part.

  The left and right fastening members are fixed by a cured product of the diaper main body and the reactive urethane hot melt adhesive.

  The fastening member is joined to a member constituting the diaper main body. As a joining mode of the fastening member, a mode in which an outer surface side of the back sheet and a skin surface side of the fastening member are joined (aspect 1); a skin surface side of the top sheet and an outer surface side of the fastening member are joined. Aspect (Aspect 2); Aspect (Aspect 3) in which the outer surface side of the top sheet and the skin surface side of the fastening member, and the skin surface side of the back sheet and the outer surface side of the fastening member are joined. The main body has a side sheet, and the outer surface side of the side sheet and the skin surface side of the fastening member, and the skin surface side of the back sheet and the outer surface side of the fastening member are joined (embodiment 4); Is mentioned. Among these, the said aspects 3 and 4 are preferable.

  When the fastening member is bonded to the diaper main body by both the skin surface side and the outer surface side, at least one of the bonding surfaces may be fixed by a cured product of the reactive urethane hot melt adhesive. In this case, a conventional hot melt adhesive can be used for the other joint surfaces.

In the joint portion using the reactive urethane hot melt adhesive, the application amount of the reactive hot melt adhesive is preferably 5 g / m ² or more, more preferably 10 g / m ² or more, and further preferably 15 g / m ^2. It is above, and 100 g / m < ² > or less is preferable, More preferably, it is 80 g / m < ² > or less, More preferably, it is 50 g / m < ² > or less. If the application amount of the reactive hot melt adhesive is 5 g / m ² or more, the adhesive strength is further improved, and if it is 100 g / m ² or less, the reactive hot melt adhesive oozes out of the diaper during production. It is suppressed.

  The peeling time between the fastening member and the material of the diaper main body joined to the fastening member is preferably 1000 minutes or more, more preferably 2000 minutes or more, and further preferably 2500 minutes or more. The measuring method of peeling time is mentioned later. In addition, when the conventional non-reactive hot melt adhesive is used, the peeling time from the raw material of the diaper main body joined to the fastening member is usually less than 200 minutes.

(Concrete example)
Hereinafter, although the disposable diaper of this invention is demonstrated, referring drawings, this invention is not limited to the aspect shown by drawing.

  Drawing 1 is a top view which looked at disposable diaper 1 concerning one embodiment of the present invention from the top sheet 10 side in the state where it developed. FIG. 2 is a plan view of the disposable diaper 1 as viewed from the backsheet 20 side in the unfolded state. FIG. 3 is a cross-sectional view of the disposable diaper 1 taken along line VV in FIG. FIG. 4 is a perspective view showing a state in which the disposable diaper of FIG. 1 is worn. 1 and 2 show a state where a side seat elastic member 41, a waist elastic member 51, and a leg elastic member 52, which will be described later, are all extended. In the figure, the arrow A is defined as the front-rear direction and the arrow B is defined as the width direction. The direction on the surface formed by the arrows A and B is defined as the plane direction. The vertical direction with respect to the surface formed by the arrows A and B represents the up-down direction C.

  As shown in FIGS. 1 to 3, the disposable diaper 1 includes a liquid-permeable top sheet 10, a liquid-impermeable back sheet 20, and an absorbent core 30 interposed between both sheets 10 and 20. The diaper main body 2 which is a laminated body is provided.

  The diaper main body 2 has a front part 2a applied to the wearer's abdomen, a rear part 2b applied to the back of the wearer, and a crotch part 2c connecting the front part 2a and the rear part 2b. Hereinafter, the direction in which the front abdominal part 2a, the crotch part 2c, and the back part 2b are connected is referred to as “front-rear direction”, and the direction perpendicular to the front-rear direction and along the surface of the diaper body 2 is referred to as “width direction”. The diaper main body 2 extends in the front-rear direction from the front part 2a to the rear part 2b, and is constricted in the width direction at the crotch part 2c located in the middle.

  The top sheet 10 is a liquid-permeable sheet disposed on the skin surface side of the diaper main body 2. The top sheet 10 extends in a band shape from the front part 2 a to the rear part 2 b, and the dimension in the width direction is smaller than the dimension in the width direction of the outer edge of the diaper main body 2.

  The back sheet 20 is a liquid-impermeable sheet disposed on the outer surface side of the diaper main body 2. The backsheet 20 has substantially the same shape as the diaper body 2 in plan view. That is, the back sheet 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. As shown in FIG. 3, the absorbent core 30 is fixed between the top sheet 10 and the back sheet 20 by a hot melt adhesive 55. Moreover, as shown in FIG. 1, the absorption core 30 is formed slightly smaller than the outer edge of the diaper main body 2 in plan view.

  A second fastening portion 70 is provided on the outer surface side of the front portion of the backsheet 20. In FIG. 2, the shape of the second fastening portion 70 is a rectangular shape, but is not limited to this shape.

  On the upper surface side of the top sheet 10, a pair of side sheets 40 for preventing urine leakage to the side is provided. The pair of side sheets 40 extends 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 is adhered to the upper surface of another sheet via the hot melt adhesive 55 at the side edge on the outer side in the width direction. The side edge portion on the inner side in the width direction of the side sheet 40 is not attached to the upper surface of the top sheet 10 and can rise with respect to the top sheet 10.

  A plurality of side seat elastic members 41 extending in the front-rear direction are disposed on the side edge portion of the side seat 40 in the width direction. The side sheet elastic member 41 is attached to the side sheet 40 with an adhesive (not shown) in a state of being extended beyond the natural length. For this reason, the elastic member 41 for side sheets generates the elastic force which shrinks the side sheet 40 to a longitudinal direction.

  When the disposable diaper is opened, the side edge of the side seat 40 on the inner side in the width direction rises due to the elastic force of the side seat elastic member 41. Thereby, a pair of upstanding weirs are formed on the upper surface of the diaper main body 2, and leakage of urine excreted by the wearer to the side is prevented.

  A plurality of waist elastic members 51 extending in the width direction are provided on 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) in a state where the elastic member 51 is stretched beyond the natural length. Therefore, the waist elastic member 51 generates an elastic force that contracts the front portion 2a and the rear portion 2b in the width direction. When the wearer wears the disposable diaper 1, the front part 2 a and the rear part 2 b can be fitted around the waist of the wearer by the contraction force of the waist elastic member 51.

  Further, a plurality of leg-around elastic members 52 extending in the front-rear direction are provided on both side edges in the width direction of the crotch portion 2c. The leg-around elastic member 52 is attached between the side sheet 40 and the back sheet 20 with an adhesive (not shown) in a state where the elastic member 52 is extended beyond the natural length. For this reason, the leg-hole elastic member 52 generates an elastic force that contracts both side edges of the crotch 2c in the longitudinal direction. When the wearer wears the disposable diaper 1, both side edges of the crotch 2 c can be fitted to the wearer's thigh by the contraction force of the leg-around elastic member 52.

  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 yarns may be used. Further, instead of the thread-like elastic member, a flat 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 includes a fastening base 61 and two tongue-shaped tabs 62 projecting outward in the width direction from the end of the fastening base 61 on the free end side. A first fastening portion 63 is provided on the skin side surface of each knob portion 62. A hook material (male member) of a hook-and-loop fastener is used for the first fastening part 63 of the present embodiment. On the other hand, as shown in FIG. 2, the 2nd fastening part 70 which attaches the 1st fastening part 63 so that attachment or detachment is possible is provided in the outer surface of the front part 2a of the diaper main body 2. As shown in FIG. A loop material (female member) of a hook-and-loop fastener is used for the second fastening portion 70 of the present embodiment.

  The base material 61 of each fastening member 60 is fixed to a portion of the rear portion 2b of the diaper main body 2 that protrudes outward in the width direction from the crotch portion 2c. Specifically, as shown in FIG. 3, the base member 61 of the fastening member 60 is fixed between the side sheet 40 and the back sheet 20 via an adhesive. In this embodiment, the side sheet 40 and the fastening base material 61 are fixed by a cured product 80 of a reactive urethane hot melt adhesive, and the back sheet 20 and the fastening base material 61 are attached by the hot melt adhesive 55. It is fixed.

  When the disposable diaper 1 is worn, 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 to the abdominal surface side along the wearer's side waist, and the first fastening part 63 is attached to the second fastening part 70. Thereby, as shown in FIG. 4, the front part 2a and the rear part 2b of the diaper main body 2 are fastened, and a waistline is formed.

  Hereinafter, the present invention will be described in detail by way of examples. However, the present invention is not limited to the following examples, and all modifications and embodiments without departing from the gist of the present invention are not limited thereto. Included in range.

[Evaluation methods]
(Elastic modulus of cured product)
The elastic modulus of the cured product was measured according to the procedures of JIS K 7127 (1999) and JIS K 7161-1 (2014).
Specifically, the reactive hot melt adhesive composition was coated on release paper so that the film thickness after drying was 0.2 mm. This coating film was allowed to stand for 168 hours in an atmosphere of a temperature of 23 ° C. and a humidity of 50% RH to be cured. After the cured coating film is peeled off from the release paper, it is punched out to give a test piece (Test piece type 2 dumbbell described in JIS K 6251 (2017) (parallel portion thickness 0.2 mm, parallel portion width 10 mm, standard The distance between lines was 20 mm)).
About the said test piece, the tension test was done using the tensile testing machine (The Shimadzu Corporation make, Autograph (trademark) AGS-X). The measurement conditions were a test speed of 10 mm / min, a test atmosphere of 23 ° C., 50% RH, and a distance between grips of 90 mm. The tensile elastic modulus was calculated | required by the following formula.
Tensile modulus (MPa) = (σ ₂ −σ ₁ ) / (0.0025−0.0005)
[In the formula, σ ₁ represents stress at a strain of 0.0005, and σ ₂ represents stress at a strain of 0.0025. ]

(Peeling time)
After the preparation, a test piece was cut out from a disposable diaper that had passed 5 days or more at room temperature. The test piece is a region from the diaper main body positioned inward in the width direction from the fastening member to the fastening member positioned outward in the width direction from the diaper main body through a portion (joint portion) where the fastening member and the diaper main body overlap. Including. The test piece had a length (diaper width direction) of 100 mm and a width of 25 mm, and the length of the joint was 26.5 mm. The application amount of the reactive hot melt adhesive at the joint is 30 g / m ² . Next, after attaching a weight of 500 g to the fastening member, the diaper main body side is turned up, the member fixed with the fastening member and the reactive hot melt adhesive is lifted, and the fastening member is placed in the diaper main body in an atmosphere of 40 ° C. The time to fall away from was measured.

[Preparation of reactive urethane hot melt adhesive]
Hereinafter, although an adhesive agent is demonstrated concretely, it is not limited to these material compositions. The raw materials and preparation methods used are as follows.
Polyol compound (A): Polyester polyol (polyester compound comprising ethylene glycol, neopentyl glycol, adipic acid, isophthalic acid as a constituent, number average molecular weight: 2000)
Polyol compound (B): Polyester polyol (polyester compound comprising diethylene glycol and phthalic acid as a constituent component, number average molecular weight: 2000)
Polyol compound (C): Polyester polyol (polyester compound having ethylene glycol and adipic acid as constituent components, number average molecular weight: 2000)
Polyisocyanate compound: Diphenylmethane diisocyanate (trade name “Millionate MT” manufactured by Tosoh Corporation)
Additive (A): Compound obtained by mixing synthetic rubber (SBS), tackifier and oil component

(1) Reactive hot melt adhesive No. 1
150 parts by mass of the polyol compound (A), 150 parts by mass of the polyol compound (B), 200 parts by mass of the polyol compound (C), and 50 parts by mass of the additive (A) were charged into a 1 L glass round bottom flask, and the internal temperature was 95. The mixture was dehydrated under reduced pressure for 1 hour with stirring at ° C. Thereafter, the pressure was returned to normal pressure with nitrogen, 100 parts by mass of a polyisocyanate compound (diphenylmethane diisocyanate) was added, the internal temperature was raised to 120 ° C., and the mixture was reacted for 1 hour under a nitrogen stream. In addition, the molar ratio of the total number of hydroxy groups that the polyol compounds (A) to (C) have and the isocyanate group that the polyisocyanate compound has is 1.6. Thereafter, dehumidification under reduced pressure was further performed at 120 ° C. for 1 hour to obtain a moisture-curable reactive hot melt adhesive containing a urethane prepolymer having an isocyanate group. The reactive hot melt adhesive is composed of a urethane prepolymer and an additive. The number average molecular weight of the urethane prepolymer is 4100. The obtained reactive hot melt adhesive is solid at 25 ° C., and the content of isocyanate groups is 1.9% by mass. The tensile modulus of the cured product of this reactive hot melt adhesive was 1.5 MPa.

[Production of disposable diapers]
The disposable diaper shown in FIGS. 1-3 was produced. In addition, it produced as usual except the fixing method of a fastening member. The attachment method of the fastening member was as follows. First, a reactive hot-melt adhesive was applied to the skin surface side of a fastening substrate made of a spunbonded nonwoven fabric (weighing 67 g / m ² ), and a SMMS (spunbond-meltblown-meltblown-spunbond) nonwoven fabric (meshing 16 g / m) ² ) Joined to the outer surface side of the side sheet. At the joint, six reactive hot melt adhesives were formed so as to extend in the width direction of the diaper at intervals of 3.5 mm with linear application portions having a width of 1.5 mm. The application amount of the reactive hot melt adhesive at the joint was 30 g / m ² .

Next, five 3 mm-wide linear hot-melt adhesive application portions are formed at intervals of 1 mm on the skin surface side of the SMMS nonwoven fabric (weight per unit: 15 g / m ² ) constituting the back sheet, and the fastening base material And the fastening member was fixed by joining with the outer surface side of a side seat | sheet. The produced disposable diaper was allowed to stand for 72 hours in an atmosphere at a temperature of 15 to 35 ° C. and a humidity of 40 to 70% RH to cure the reactive hot melt adhesive.

  The obtained disposable diaper had a good texture at the joint between the fastening member and the diaper main body. Moreover, the peeling time of this junction part was 2500 minutes or more.

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: Elastic member for waist circumference, 52: Elastic member for foot circumference, 55: Hot melt adhesive, 60: Fastening member, 61: Fastening base material, 62: Knob part, 63: First fastening part, 70: Second fastening part, 80: Cured product of reactive urethane hot melt adhesive.

Claims (6)

A diaper body having an absorbent core;
Left and right fastening members respectively joined to both side edges of the rear portion of the diaper main body and extending outward in the lateral direction from the diaper main body;
First fastening portions respectively provided on the skin surface side of the left and right fastening members;
A second fastening part provided on the outer surface side of the front part of the diaper main body, wherein the first fastening part is detachably fastened,
The diaper main body and the fastening member are fixed by a cured product of a reactive urethane hot melt adhesive,
The reactive urethane hot melt adhesive contains a polyurethane prepolymer having an isocyanate group at the end of the molecular chain,
The polyurethane prepolymer is obtained by reacting a polyol composition and a polyisocyanate composition,
The polyol composition contains a polyester polyol having a number average molecular weight of 500 to 10,000,
The polyisocyanate composition contains a diisocyanate and does not contain an isocyanurate-modified product of diisocyanate,
The isocyanate group content (JIS K 1603-1A method) before curing of the reactive urethane hot melt adhesive is 0.8 mass% to 5.0 mass%,
The disposable diaper characterized by the tensile elasticity modulus of the hardened | cured material of the said reactive urethane hot-melt-adhesive being 0.1 MPa-50 MPa.   The disposable diaper according to claim 1, wherein the polyester polyol contains, as a constituent component, a diol having an alkylene structure having 2 or more carbon atoms or a dicarboxylic acid having an alkylene group having 2 or more carbon atoms.   The diisocyanate contains at least one selected from the group consisting of diphenylmethane diisocyanate, dimethyldiphenylmethane diisocyanate, dicyclohexylmethane diisocyanate, tolylene diisocyanate, hexamethylene diisocyanate, xylylene diisocyanate, phenylene diisocyanate, and isophorone diisocyanate. The disposable diaper according to 2.   The molar ratio (isocyanate group / hydroxy group) between the hydroxyl group in the polyol composition and the isocyanate group in the polyisocyanate composition is 1.2 to 3.0. The disposable diaper described.   The disposable diaper according to any one of claims 1 to 4, wherein a peeling time between the fastening member and a material of the diaper main body joined to the fastening member is 1000 minutes or more. It said fastening member and the coating amount of the reactive hot-melt adhesive at the junction between the diaper body, the disposable diaper according to any one of claims 1 to 5 which is ^{5g / m 2 ~50g / m 2} .

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