JP7311723B1 - laminate - Google Patents

Abstract

[PROBLEMS] To provide a hot-melt adhesive and a specific cellulosic adhesive, which are excellent in adhesiveness and strength over time and are used for bonding nonwoven fabrics containing cellulosic fibers to each other or bonding nonwoven fabrics containing cellulosic fibers to other nonwoven fabrics. To provide a laminate with a nonwoven fabric containing fibers. SOLUTION: A nonwoven fabric layer (I) composed of a nonwoven fabric α containing cellulosic fibers and a nonwoven fabric layer (II) composed of an arbitrary nonwoven fabric are provided in this order, and the nonwoven fabric layer (I) and the nonwoven fabric layer ( II) is bonded via a hot-melt adhesive β, and the mean deviation (SMD) of the surface roughness of the surface of the non-woven fabric α on the side in contact with the non-woven fabric layer (II) via the hot-melt adhesive β is 2.3 or less or 3.0 or more, and the hot melt adhesive β comprises component (A) thermoplastic elastomer, and component (B) tackifier comprising component (B1) and component (B2) agent, the component (B1) is a terpene-based tackifier, a rosin-based tackifier, or a fully hydrogenated hydrocarbon-based tackifier, and the component (B2) is an unhydrogenated hydrocarbon-based tackifier A laminate characterized by being an imparting agent or a partially hydrogenated hydrocarbon-based tackifier. [Selection figure] None

Description

The present invention relates to laminates.

Currently, one-way plastics are mainly used as materials for sanitary products such as diapers and napkins. However, it is expected that these materials will be increasingly replaced by environmentally friendly materials in the future.

Non-woven fabrics made of petroleum-based materials are currently mainly used as materials for such sanitary products, and it is expected that non-woven fabrics made of natural-based materials will replace them in the future.

A nonwoven fabric made of a petroleum-based base material and a nonwoven fabric made of a natural-based base material have different surface states. For this reason, when the adhesive used in the manufacture of conventional sanitary goods is used in the step of laminating nonwoven fabrics made of natural base materials, appropriate adhesiveness cannot be obtained.

When laminating nonwoven fabrics used in such sanitary products with an adhesive, the nonwoven fabrics adhere well on the spot, and the adhesiveness is maintained even after a long period of time (hereinafter referred to as In this specification, the property is referred to as "strength over time"). For that purpose, in addition to the surface characteristics of the nonwoven fabric, selection of an adhesive to be combined with it is also important.

Patent Literature 1 discloses a hot-melt adhesive that is said to have good adhesiveness even to uneven materials such as those used in sanitary products as described above.

Further, Patent Document 2 discloses a hot-melt adhesive that is said to have good adhesion to hydrophilic substrates such as cellulose-based substrates and cotton-based substrates.

International Publication No. 2021/039118 JP 2007-169531 A

However, it is unclear whether the hot melt adhesive disclosed in Patent Document 1 is a good adhesive even for nonwoven fabrics made from natural base materials. It is unclear whether consideration is given to the strength over time of

Also, with regard to the hot melt adhesive disclosed in Patent Document 2, although the adhesiveness between the PET film and the cotton cloth has been confirmed in Examples, The adhesiveness to the non-woven fabric is unknown, and it is unclear whether the design takes into consideration the strength over time.

In view of the circumstances as described above, the object of the present invention is to bond nonwoven fabrics containing cellulosic fibers, or between nonwoven fabrics containing cellulosic fibers and other nonwoven fabrics, which are excellent in adhesiveness and strength over time. To find a laminate of a hot-melt adhesive and a nonwoven fabric containing specific cellulosic fibers, which is used for

As a result of extensive research to solve the above problems, the present inventors have found that by adopting a combination of a nonwoven fabric containing cellulosic fibers having a predetermined surface roughness and a hot-melt adhesive having a predetermined composition, , excellent adhesion and strength over time can be obtained. Based on this finding, the inventors have further studied and completed the present invention.

That is, the present invention provides the following laminate.
Section 1.
It has a nonwoven fabric layer (I) composed of a nonwoven fabric α containing cellulose fibers and a nonwoven fabric layer (II) composed of an arbitrary nonwoven fabric in this order, and the nonwoven fabric layer (I) and the nonwoven fabric layer (II) are The surface roughness average deviation (SMD) of the surface of the nonwoven fabric α on the side in contact with the nonwoven fabric layer (II) via the hot melt adhesive β is 2.3 or less. or 3.0 or more,
The hot melt adhesive β comprises component (A) a thermoplastic elastomer, and component (B) a tackifier comprising components (B1) and (B2),
The component (B1) is a terpene-based tackifier, a rosin-based tackifier, or a fully hydrogenated hydrocarbon-based tackifier,
The laminate, wherein the component (B2) is an unhydrogenated hydrocarbon tackifier or a partially hydrogenated hydrocarbon tackifier.
Section 2.
Item 2. The laminate according to Item 1, wherein the nonwoven fabric α has a basis weight of 15 to 40 g/m ² .
Item 3.
Item 3. The laminate according to Item 1 or 2, wherein the cellulosic fiber contained in the nonwoven fabric α is cotton or rayon.
Section 4.
Item 3. The laminate according to item 1 or 2, wherein the (B2) is a partially hydrogenated hydrocarbon-based tackifier.
Item 5.
Item 3. The laminate according to Item 1 or 2, wherein the hot melt adhesive β contains wax.
Item 6.
Item 3. The laminate according to Item 1 or 2, wherein the hot melt adhesive β is a hot melt adhesive for absorbent articles.

The laminate according to the present invention as described above is also excellent in adhesiveness and strength over time.

Explanatory drawing of laminated body preparation of an Example and a comparative example.

As used herein, "contain" is a concept that includes both "comprise," "consist essentially of," and "consist of." Further, in this specification, when a numerical range is indicated by "A to B", it means from A to B.

(1. Laminate)
The laminate of the present invention has a nonwoven fabric layer (I) composed of a nonwoven fabric α containing cellulosic fibers and a nonwoven fabric layer (II) composed of an arbitrary nonwoven fabric in this order, and the nonwoven fabric layer (I) and the nonwoven fabric layer (II) The nonwoven fabric layer (II) is adhered via a hot melt adhesive β, and the average deviation of the surface roughness ( SMD) is 2.3 or less or 3.0 or more, and the hot melt adhesive β comprises component (A) thermoplastic elastomer, and component (B1) and component (B2). ) containing a tackifier, the component (B1) is a terpene-based tackifier, a rosin-based tackifier, or a fully hydrogenated hydrocarbon-based tackifier, and the component (B2) is an unhydrogenated carbonized It is characterized by being a hydrogen-based tackifier or a partially hydrogenated hydrocarbon-based tackifier.

In addition to the laminate of the present invention, one or more sheets of nonwoven fabric (it may be the same nonwoven fabric as nonwoven fabric α) is added with a separate hot-melt adhesive (hot-melt adhesive similar to hot-melt adhesive β). It is also a preferred embodiment to laminate by bonding using an adhesive.

Before and after the step of bonding the nonwoven fabric constituting the laminate of the present invention via a hot-melt adhesive, a method of subjecting the nonwoven fabric or laminate to processing such as embossing and perforation is also a preferred method. It is a mode.

(2. Nonwoven fabric layer (I))
The nonwoven fabric layer (I) is composed of a nonwoven fabric α containing cellulosic fibers. The content of the cellulosic fiber in the nonwoven fabric α is preferably 5% by mass or more, more preferably 20% by mass or more, and even more preferably 50% by mass or more based on 100% by mass of the nonwoven fabric α. In addition, it is preferable that the content of the cellulosic fiber is 100% by mass or less in 100% by mass of the nonwoven fabric α. Alternatively, the nonwoven fabric α may be composed only of cellulosic fibers.

A wide range of known cellulose fibers can be used. Specific examples include cotton, rayon, and lyocell, but are not limited to these.

The basis weight of the nonwoven fabric α is preferably 15 g/m ² or more, more preferably 25 g/m ² or more. When the nonwoven fabric α has a basis weight of 15 g/m ² or more, a good water retention effect can be imparted. The basis weight of the nonwoven fabric α is preferably 40 g/m ² or less, more preferably 35 g/m ² or less. When the nonwoven fabric α has a basis weight of 40 g/m ² or less, good air permeability can be imparted.

The average deviation (SMD) of the surface roughness of the surface of the nonwoven fabric α constituting the nonwoven fabric layer (I), which is in contact with the nonwoven fabric layer (II) via the hot melt adhesive β, is 2.3 or less or 3.0. That's it. If the value is greater than 2.3 or less than 3.0, the smoothness of the surface will decrease and the texture will deteriorate, or the contact area of the surface will increase and the texture will deteriorate. .

In this specification, the mean deviation (SMD) of the surface roughness of the nonwoven fabric surface is specifically defined as being measured and calculated as follows.

As a measuring instrument, a surface tester (for example, KES-FB4-A manufactured by Kato Tech Co., Ltd.) is used, and the measurement conditions are a temperature of 23 ° C and a humidity of 50%. As a sensor, a test piece (20 cm × 20 cm) of the nonwoven fabric to be tested is used, SPEED is 1.0 mm / sec, roughness static load is 10.0 gf, 100 g paperweight is used to apply tension to the nonwoven fabric, The MD direction of the nonwoven fabric is measured.

As a test procedure, a test piece is set so that the MD direction of the nonwoven fabric and the movement direction of the sensor are the same, and a tension of 100 g is applied to the nonwoven fabric in the MD direction to measure the surface roughness. The measurement shall be performed at 12 randomly selected nonwoven fabrics and the average value shall be obtained as SMD.

The average deviation (SMD) of the surface roughness of the surface of the nonwoven fabric α constituting the nonwoven fabric layer (I), which is in contact with the nonwoven fabric layer (II) via the hot melt adhesive β, is 2.3 or less. It is preferably 2.0 or less, more preferably 1.8 or less. Moreover, SMD is preferably 0 or more, and more preferably 1.0 or more.

On the other hand, the nonwoven fabric α constituting the nonwoven fabric layer (I) has a surface roughness mean deviation (SMD) of 3.0 or more on the side in contact with the nonwoven fabric layer (II) via the hot melt adhesive β. is preferred, 3.2 or more is more preferred, and 3.5 or more is even more preferred. Also, the SMD is preferably 7.0 or less, more preferably 6.5 or less.

(3. Nonwoven fabric layer (II))
The nonwoven fabric layer (II) is composed of any nonwoven fabric. As such a nonwoven fabric, a wide range of known nonwoven fabrics can be employed, and among them, nonwoven fabrics containing cellulosic fibers or nonwoven fabrics composed only of cellulosic fibers are preferable. Of course, a nonwoven fabric similar to the nonwoven fabric α described above may be used.

In addition, a nonwoven fabric made of a petroleum-based base material, which has been conventionally used for sanitary products, may also be used.

(4. Hot melt adhesive β)
The hot-melt adhesive β contains component (A) a thermoplastic elastomer and component (B) a tackifier comprising components (B1) and (B2).

(4.1. Component (A) thermoplastic elastomer)
The component (A) thermoplastic elastomer is not particularly limited, and examples thereof include styrene block copolymers, olefin block copolymers, polyurethane block copolymers, and polyester block copolymers. Among these, styrenic block copolymers are preferred from the viewpoint of further improving the peel strength of the hot-melt adhesive.

A styrene-based block copolymer is a block copolymer obtained by block-copolymerizing a vinyl-based aromatic hydrocarbon and a conjugated diene compound.

A vinyl aromatic hydrocarbon is an aromatic hydrocarbon compound having a vinyl group. Specific examples of vinyl aromatic hydrocarbons include styrene, o-methylstyrene, p-methylstyrene, p-tert-butylstyrene, 1,3-dimethylstyrene, α-methylstyrene, vinylnaphthalene, and vinylanthracene. etc., among which styrene is preferred. The vinyl aromatic hydrocarbons can be used alone or in combination of two or more.

A conjugated diene compound is a diolefin compound having at least one pair of conjugated double bonds. Specific examples of conjugated diene compounds include 1,3-butadiene, 2-methyl-1,3-butadiene (isoprene), 2,3-dimethyl-1,3-butadiene, 1,3-pentadiene, 1,3-butadiene, 3-hexadiene, etc., among which 1,3-butadiene and 2-methyl-1,3-butadiene (isoprene) are preferred. A conjugated diene compound can be used individually or in combination of 2 or more types, respectively.

The styrenic block copolymer is preferably an unhydrogenated styrenic block copolymer because it can exhibit better peel strength. Examples of the unhydrogenated styrene block copolymer include styrene-butadiene block copolymer (SB), styrene-butadiene-styrene block copolymer (SBS), and styrene-isoprene-styrene block copolymer. (SIS), styrene-butadiene-styrene-butadiene block copolymer (SBSB), and the like. These styrenic block copolymers may be used alone or in combination of two or more. Among these styrenic block copolymers, styrene-butadiene-styrene block copolymers (SBS) are preferred because they can exhibit even better peel strength.

The content of the styrene skeleton in the styrene block copolymer is preferably 10 to 70% by mass, preferably 30 to 60% by mass, based on 100% by mass of the styrene block copolymer, in order to achieve better peel strength. % is more preferred.

In the present specification, the styrene skeleton content ratio in the styrene block copolymer refers to the content ratio (% by mass) of the styrene block in the styrene block copolymer. Examples of the method for calculating the styrene skeleton content in the styrene block copolymer include methods using proton nuclear magnetic resonance, infrared spectroscopy, etc. according to JIS K6239.

In the present invention, the component (A) thermoplastic elastomer is a styrene-based block copolymer, and the styrene-based block copolymer is a styrene-butadiene-styrene block, because it can exhibit better peel strength. It preferably contains a copolymer (SBS).

In the present invention, the styrene-based block copolymer is an asymmetric styrene-isoprene-styrene block copolymer from the viewpoint of further improving the heat stability when heated at a high temperature for a long time (for example, heating at 160 ° C. for 72 hours). It is preferable not to contain

In the present invention, the component (A) thermoplastic elastomer is preferably a styrenic block copolymer, and the styrenic block copolymer does not contain an asymmetric styrene-isoprene-styrene block copolymer.

In the present invention, the styrenic block copolymer more preferably contains a styrene-butadiene-styrene block copolymer (SBS) and does not contain an asymmetric styrene-isoprene-styrene block copolymer.

As used herein, "asymmetric" in an asymmetric styrene-isoprene-styrene block copolymer means that the styrene phases at both ends have different styrene skeleton content.

A wide range of known commercial products can be used as the styrenic block copolymer. Commercially available products include, for example, Asahi Kasei's product name "Asaprene T-439" (styrene skeleton content: 45% by mass), Asahi Kasei's product name "Asaprene T-438" (styrene skeleton content: 35% by mass. %), product name “Asaprene T-436” manufactured by Asahi Kasei Corporation (styrene skeleton content: 30% by mass), product name “DX-405” manufactured by Kraton Polymer Co., Ltd. (styrene skeleton content: 24% by mass), Kraton Polymer company product name "D-1155" (styrene skeleton content: 40% by mass), Kraton Polymer product name "D-1118" (styrene skeleton content: 30% by mass), CHIMEI "PB5502" (styrene skeleton content ratio: 32% by mass) and the like. These commercial products can be used alone or in combination of two or more.

The content of the thermoplastic elastomer (A) in 100% by mass of the hot melt adhesive of the present invention is preferably 10 to 35% by mass, more preferably 15 to 35% by mass, from the viewpoint that better peel strength can be exhibited. 30% by mass, more preferably 18 to 25% by mass.

The content of the styrenic block copolymer in 100% by mass of the hot melt adhesive of the present invention is preferably 10 to 35% by mass, more preferably 15% by mass, from the viewpoint of being able to exhibit even better peel strength. to 30% by mass, more preferably 18 to 25% by mass.

(4.2. Component (B) tackifier)
Component (B) tackifier comprises component (B1) and component (B2). The component (B) tackifier may be in an aspect consisting only of component (B1) and component (B2).

Component (B1) is a terpene-based tackifier, a rosin-based tackifier, or a fully hydrogenated hydrocarbon-based tackifier.

Examples of the terpene-based tackifier include terpene resins (monoterpene, diterpene, triterpene, polypertene, etc.), terpene phenol resins, aromatic modified terpene resins, and the like. These terpene-based tackifiers may be used alone or in combination of two or more.

As the terpene-based tackifier, a wide range of known commercial products having an acid value of 15 mgKOH/g or less can be used. Examples of such commercial products include product name "YS Resin TO-105" (acid value: 0 mgKOH/g) manufactured by Yasuhara Chemical Co., Ltd., product name "SYLVARES TRM1115" (acid value: 0 mgKOH/g) manufactured by Kraton, and the like. mentioned.

As the rosin-based tackifier, it is preferable to use at least one of natural rosin and an esterified product of the natural rosin (rosin ester resin) from the viewpoint of exhibiting better adhesiveness (tack). It is more preferable to use

Examples of the natural rosin include tall rosin, gum rosin, and wood rosin. These natural rosins can be used alone or in combination of two or more.

Examples of the rosin ester resin include rosin glycerin ester, rosin pentaerythritol ester, rosin methyl ester, rosin ethyl ester, rosin butyl ester, and rosin ethylene glycol ester. These rosin ester resins may be used alone or in combination of two or more.

As the rosin-based tackifier, a wide range of known commercial products having an acid value of 15 mgKOH/g or less can be used. The commercial products include, for example, Arakawa Chemical Industries, Ltd., product name "Super Ester A100" (acid value: 5 mgKOH/g), Arakawa Chemical Industries, Ltd., product name "Pine Crystal KE-100" (acid value: 6 mgKOH /g), product name “SYLVALITE 9100” (acid value: 7 mgKOH/g) manufactured by Kraton, product name “Superester A75” (acid value: 5 mgKOH/g) manufactured by Arakawa Chemical Industries, Ltd., and the like. These commercial products can be used alone or in combination of two or more.

Examples of the fully hydrogenated hydrocarbon-based tackifier include fully hydrogenated petroleum resins obtained by adding hydrogen to petroleum resins such as C5 petroleum resins, C9 petroleum resins, C5C9 petroleum resins, and dicyclopentadiene petroleum resins. can be exemplified. The C5 petroleum resin is a petroleum resin made from a C5 fraction of petroleum, the C9 petroleum resin is a petroleum resin made from a C9 fraction of petroleum, and the C5C9 petroleum resin is a petroleum resin. It is a petroleum resin made from a C5 fraction and a C9 fraction. C5 fractions include cyclopentadiene, isoprene, pentane, and the like. The C9 fraction includes styrene, vinyltoluene, indene, and the like.

Component (B2) is an unhydrogenated hydrocarbon tackifier or a partially hydrogenated hydrocarbon tackifier.

Specific examples of the tackifier of component (B2) include non-hydrogenated or partially hydrogenated petroleum resins such as the above-mentioned C5-based petroleum resins, C9-based petroleum resins, C5C9-based petroleum resins, and dicyclopentadiene-based petroleum resins. can be exemplified by hydrocarbon-based tackifiers.

As used herein, the ring and ball softening point of the component (B) tackifier means the temperature measured according to JIS K 6863.

The content of the component (B) tackifier in 100% by mass of the hot melt adhesive β is preferably 30 to 65% by mass, more preferably 35 to 60% by mass, from the viewpoint of further improving the peel strength. More preferably, it is 40 to 55% by mass.

The content of component (B) tackifier is preferably 150 to 350 parts by mass, more preferably 200 to 300 parts by mass, based on 100 parts by mass of component (A) thermoplastic elastomer, from the viewpoint of further improving the peel strength. part by mass.

In the present invention, where A is the part by mass of the component (A) thermoplastic elastomer and B is the part by mass of the component (B) tackifier, the ratio represented by B/A is preferably from 1.5 to 3.5, more preferably 2.0 to 3.0.

In addition, the amount of component (B1) in 100% by mass of the total amount of components (B1) and (B2) is preferably 50% by mass or less, and 40% by mass or less, in order to obtain good adhesiveness. is more preferable.

On the other hand, the amount of component (B1) blended in 100% by mass of the total amount of components (B1) and (B2) is preferably 5% by mass or more, more preferably 10% by mass or more. By setting the amount of component (B1) to be 5% by mass or more, excellent strength over time can be obtained.

(4.3. Various additives)
The hot-melt adhesive β may contain various additives, if necessary, as long as the object of the present invention is not essentially hindered. Various additives include plasticizers, antioxidants, ultraviolet absorbers, liquid rubbers, waxes, and particulate fillers.

Examples of plasticizers include naphthenic process oils, paraffinic process oils, etc. Naphthenic process oils are preferred from the viewpoint of further improving heat-stable peel strength. These plasticizers may be used alone or in combination of two or more.

A wide range of known commercial products can be used as the plasticizer.

Commercially available naphthenic process oils include, for example, the product name "KN4010" manufactured by PetroChina Co., Ltd., the product name "Dianafresia N28" manufactured by Idemitsu Kosan Co., Ltd., the product name "Dianafrecia U46" manufactured by Idemitsu Kosan Co., Ltd., Nynas company's product name "Nyflex222B" etc.

Commercially available products of paraffin-based process oil include, for example, product name "Diana Process Oil PW32", product name "Diana Process Oil PW90", product name "Diana Process Oil PS32", product name "Diana Process Oil PS90" manufactured by Idemitsu Kosan Co., Ltd. "; a product name "Kaydol" manufactured by Witco, and the like.

When the hot-melt adhesive β contains a plasticizer, the upper limit of the content of the plasticizer in 100% by mass of the hot-melt adhesive is preferably 40% by mass, more preferably 30% by mass, and even more preferably 25% by mass. % by mass.

When the hot-melt adhesive β contains a plasticizer, the lower limit of the content of the plasticizer (C) in 100% by mass of the hot-melt adhesive is preferably 1% by mass, more preferably 5% by mass.

As the antioxidant, a wide range of known antioxidants can be used, such as 2,6-di-t-butyl-4-methylphenol, n-octadecyl-3-(4'-hydroxy-3',5' -di-t-butylphenyl)propionate, 2,2'-methylenebis(4-methyl-6-t-butylphenol), 2,2'-methylenebis(4-ethyl-6-t-butylphenol), 2,4- Bis(octylthiomethyl)-o-cresol, 2-t-butyl-6-(3-t-butyl-2-hydroxy-5-methylbenzyl)-4-methylphenyl acrylate, 2,4-di-t- amyl-6-[1-(3,5-di-t-amyl-2-hydroxyphenyl)ethyl]phenyl acrylate, 2-[1-(2-hydroxy-3,5-di-tert-pentylphenyl)] Phenolic antioxidants such as acrylates, tetrakis [methylene-3-(3,5-di-t-butyl-4-hydroxyphenyl) propionate] methane; dilauryl thiodipropionate, lauryl stearyl thiodipropionate, penta sulfur-based antioxidants such as erythritol tetrakis(3-laurylthiopropionate); phosphorus-based antioxidants such as tris(nonylphenyl)phosphite and tris(2,4-di-t-butylphenyl)phosphite is mentioned. These antioxidants may be used alone or in combination of two or more. Among these antioxidants, phenolic antioxidants are preferred from the viewpoint of further improving heat stability.

As the antioxidant, a wide range of known commercial products can be used. Commercially available phenolic antioxidants include, for example, the product name "Evernox 10" manufactured by EVERSPRING CHEMICAL.

When the hot melt adhesive β contains an antioxidant, the upper limit of the content of the antioxidant in 100% by mass of the hot melt adhesive is preferably 5% by mass, more preferably 4% by mass, and even more preferably It is 3% by mass.

When the hot melt adhesive β contains an antioxidant, the lower limit of the content of the antioxidant in 100% by mass of the hot melt adhesive is preferably 0.1% by mass, more preferably 0.5% by mass. , and more preferably 1% by mass.

As the UV absorber, a wide range of known UV absorbers can be used, such as 2-(2'-hydroxy-5'-methylphenyl)benzotriazole, 2-(2'-hydroxy-3',5'-t -butylphenyl)benzotriazole, 2-(2'-hydroxy-3',5'-di-t-butylphenyl)-5-chlorobenzotriazole, and other benzotriazole-based UV absorbers; 2-hydroxy-4-methoxy benzophenone-based ultraviolet absorbers such as benzophenone; salicylic acid ester-based ultraviolet absorbers; cyanoacrylate-based ultraviolet absorbers; and hindered amine-based light stabilizers. These ultraviolet absorbers may be used alone or in combination of two or more.

As the liquid rubber, a wide range of known liquid rubbers can be used, and examples thereof include liquid polybutene, liquid polybutadiene, liquid polyisoprene, and hydrogenated resins thereof. These liquid rubbers can be used alone or in combination of two or more.

A wide variety of known fine particle fillers can be used as the fine particle filler, and examples thereof include calcium carbonate, kaolin, talc, titanium oxide, mica, and styrene beads. These particulate fillers can be used alone or in combination of two or more.

When the hot melt adhesive β contains the above additives, the content of the above additives in 100% by mass of the hot melt adhesive is preferably 5% by mass or less.

The nonwoven fabric used for the laminate of the present invention can be produced by a conventional method.

The hot-melt adhesive β may also be produced by a conventional method, and the production method is not particularly limited. For example, the components (A) and (B) and, if necessary, the various additives described above are put into a stirring kneader equipped with a heating device, and kneaded while being heated.

The heating temperature during kneading is not particularly limited, and is preferably 100 to 200°C, more preferably 120 to 180°C. The kneading time is not particularly limited, preferably 40 to 140 minutes, more preferably 60 to 120 minutes.

As a method for applying the hot-melt adhesive β in obtaining the laminate, a wide range of known coating methods can be used, for example, spiral spray coating, slot coater coating, curtain spray coating, and roll coater coating. , omega coating, dot coating, bead coating, and the like.

As the applicator for applying the hot-melt adhesive β to the adhered portion, a wide range of known applicators can be used, such as a hot-melt applicator. Examples of the hot-melt applicator include the product name "REKA handgun TR80LCD (spray)" manufactured by Suntool Co., Ltd., and the like.

The hot-melt adhesive β is used in the production of water-absorbing articles because it can exhibit excellent adhesiveness to hydrophilic non-woven fabrics and porous substrates made of natural materials such as cellulosic materials and cotton-based materials. It is suitably used for bonding adherends together. The absorbent article is preferably constructed using the hot-melt adhesive β.

Absorbent articles are intended to absorb body fluids such as blood, urine, sweat, pus, gastric juice, saliva, nasal secretion mucus. Examples of water-absorbing articles include paper diapers, sanitary napkins, panty liners, incontinence pads, portable toilets, portable waste disposal bags, animal excreta disposal sheets, hospital gowns, surgical gowns, wound dressings, and first aid Adhesive plasters, freshness preserving materials for meat, fish, and the like can be mentioned. Among these, the hot melt adhesive of the present invention is suitably used for paper diapers, sanitary napkins, panty liners and the like.

Disposable diapers consist of a liquid-impermeable back sheet made of polyolefin resin film or the like, a liquid-permeable top sheet made of non-woven fabric or the like, a liquid diffusion sheet that diffuses the liquid permeated from the top sheet, a liquid diffusion sheet, and a liquid-impermeable sheet. It is basically composed of a permeable backsheet and an absorbent disposed between it. In order to suppress the occurrence of stickiness after the absorber absorbs urine or the like, the absorber is used with its surface covered with absorbent paper such as tissue. In addition, water-absorbent articles employ a structure in which an elastic member such as rubber is attached in a stretchable manner to fit around the wearer's legs and waist to prevent excrement from leaking out.

In the manufacture of such disposable diapers, the hot-melt adhesive β is used, for example, to bond the cellulosic porous substrates together with other porous substrates such as nonwoven fabrics. It is preferably used to integrate the material by adhesion.

The method for bonding the nonwoven fabric layers (I) and (II) with the hot-melt adhesive β to form a laminate is not particularly limited, and known methods can be used. For example, after applying the hot melt adhesive β melted by heating to the nonwoven fabric layer (I) or (II), the other nonwoven fabric layer is superimposed on the coated hot melt adhesive, and these are pressed together. method is used.

Although the embodiments of the present invention have been described above, the present invention is by no means limited to such examples, and can of course be embodied in various forms without departing from the gist of the present invention.

EXAMPLES Hereinafter, embodiments of the present invention will be described more specifically based on Examples, but the present invention is not limited to these.

Production of Hot Melt Adhesive β Thermoplastic elastomer, tackifier, plasticizer, antioxidant and various additives shown in Tables 1 to 3 below are put into a stirring kneader equipped with a heating device, The mixture was heated at 145° C. and kneaded for 90 minutes to obtain production examples 1 to 19 of hot melt adhesives.

Preparation of adhesive sheet A release PET film (50 μm) coated with silicone oil was coated with the above hot melt adhesive β dissolved at 140 ° C. in a thickness of 10 μm and a width of 90 mm. An adhesive sheet was obtained by laminating a release paper (thickness: 15 μm) on the opposite side. After that, the adhesive sheet was allowed to stand for 24 hours in an atmosphere of 23° C. and a relative humidity of 50% to solidify the hot-melt adhesive. After that, the adhesive sheet was cut into a width of 25 mm and a length of 40 mm to obtain an adhesive sheet A.

Preparation of nonwoven fabrics Cotton nonwoven fabrics I to III and rayon nonwoven fabrics were prepared. The average deviation (SMD) of the surface roughness of each nonwoven fabric was measured using a surface tester (eg, KES-FB4-A manufactured by Kato Tech Co., Ltd.) as described above. 623, 3.179 for cotton nonwoven fabric II, 6.931 for cotton nonwoven fabric III, and 4.857 for rayon nonwoven fabric.

Fabrication of Laminate As shown in FIG. 1, the nonwoven fabrics I to III and the rayon nonwoven fabric were cut into a size of 70 mm in the MD direction and 50 mm in the CD direction, and the release paper of the various adhesive sheets was peeled off to measure the SMD of the nonwoven fabric. A roll of 500 g was placed thereon and reciprocated once at a speed of 5 mm/sec. Furthermore, the release film of the adhesive sheet was peeled off, and another prepared nonwoven fabric was attached to the exposed adhesive surface on the surface where the SMD measurement was performed. In both Examples and Comparative Examples, the two nonwoven fabrics sandwiching the adhesive sheet were a combination of nonwoven fabrics made of the same material. A 100 g roll was placed on the obtained laminate and reciprocated once at a speed of 5 mm/sec.

Adhesion evaluation test over time Using a tensile tester (AGS-X manufactured by Shimadzu Corporation), the nonwoven fabrics in the laminates of each example and comparative example were subjected to a T-type peel test at a tensile strength of 100 mm / min in the MD direction. Then, the convex maximum test force was measured. The measurement was performed three times, and the average value was adopted as the test result of the maximum convex test force. The measurement was carried out at three points after each Example and Comparative Example was left to stand for 24 hours under an environment of 23° C. and 50% humidity, and after standing for 1 week and 2 weeks under an environment of 50° C. after manufacturing each Example and Comparative Example. In this specification, hereinafter, the measurement results after standing for 24 hours are referred to as "initial strength", and the measurement results after standing for 1 week and 2 weeks are referred to as "1W strength" and "2W strength", respectively. do. In addition, as evaluation criteria, the following criteria were used to evaluate the average value obtained by performing the convex maximum test force measurement three times. In the following criteria, those with evaluation criteria of ◯ or ⊚ were judged to have sufficient adhesiveness.
<Evaluation Criteria>
Less than 2.00N ×
2.00N or more and less than 2.50N △
2.50N or more and less than 3.00N 〇3.00N or more ◎

Evaluation test results As shown in Tables 4 to 15 below, the laminates of Examples 1 to 52 exhibited excellent adhesion even after one week or two weeks, whereas the laminates of Comparative Examples 1 to 24 exhibited excellent adhesion. Such excellent adhesion was not confirmed in the laminate.

Claims (4)

It has a nonwoven fabric layer (I) composed of a nonwoven fabric α containing cellulose fibers and a nonwoven fabric layer (II) composed of an arbitrary nonwoven fabric in this order, and the nonwoven fabric layer (I) and the nonwoven fabric layer (II) are The surface roughness average deviation (SMD) of the surface of the nonwoven fabric α on the side in contact with the nonwoven fabric layer (II) via the hot melt adhesive β is 2.3 or less. or 3.0 or more,
The hot-melt adhesive β contains component (A) a thermoplastic elastomer and component (B) a tackifier consisting only of components (B1) and (B2),
The component (B1) is a terpene-based tackifier, a rosin-based tackifier, or a fully hydrogenated hydrocarbon-based tackifier,
The component (B2) is a partially hydrogenated hydrocarbon-based tackifier ,
10 to 35% by mass of the component (A) and 30 to 65% by mass of the component (B) are contained in 100% by mass of the hot melt adhesive β,
A laminate characterized in that the content of component (B1) is 5 to 50% by mass in 100% by mass of the total amount of components (B1) and (B2). The laminate according to claim 1, wherein the nonwoven fabric α has a basis weight of 15 to 40 g/m ² . The laminate according to claim 1 or 2, wherein the cellulosic fiber contained in said nonwoven fabric α is cotton or rayon. 3. The laminate according to claim 1, wherein the hot melt adhesive β contains wax.

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