JP2015091917A - Hot melt adhesive agent and disposable product using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a hot melt adhesive agent having enhanced wet adhesiveness to a constitutional member such as a polyolefin resin film, a nonwoven fabric, a tissue and natural rubber without reduction of thermal stability and generation of odor.SOLUTION: There is provided a hot melt adhesive agent containing (A) a thermoplastic block copolymer containing at least one kind of a block copolymer of vinyl aromatic hydrocarbon and a conjugated diene compound, and hydrogenated product thereof and (B) acid modified petroleum resin manufactured by acid modification by unsaturated carboxylic acid or anhydride thereof.

Description

  The present invention relates to a hot melt adhesive, and more particularly to a hot melt adhesive suitably used for producing disposable products such as disposable diapers.

  Conventionally, disposable products such as paper diapers and sanitary napkins have been widely used. Components such as polyolefin resin films, nonwoven fabrics, tissues, and natural rubber are used for disposable products. Disposable products are assembled by adhering these components using a hot melt adhesive.

  Hot-melt adhesives used in disposable products include rubber-based hot-melt adhesives mainly composed of a thermoplastic block copolymer obtained by copolymerizing a vinyl aromatic hydrocarbon and a conjugated diene compound, and ethylene-propylene. Olefin-based hot melt adhesives mainly composed of a copolymer are used. Among these, rubber-based hot melt adhesives are widely used because they have excellent coating properties and cohesive strength with respect to olefin-based hot melt adhesives.

  In disposable products such as disposable diapers and sanitary napkins, urine, blood, etc. touch the adhesive part between the rubber-based hot melt adhesive and the disposable member during use. Decreasing becomes a problem.

  Patent Document 1 includes an acid-modified thermoplastic block copolymer modified with a carboxylic acid and / or an acid anhydride thereof, a tackifying resin, a plasticizing oil, and a wax. A rubber-based hot melt adhesive is disclosed. Such hot melt adhesives have improved wet adhesion by the use of acid-modified thermoplastic block copolymers.

  However, acid-modified thermoplastic block copolymers reduce the thermal stability of hot melt adhesives.

  In assembling a disposable product, when a porous substrate such as a nonwoven fabric or tissue is bonded with a rubber hot melt adhesive, first, the heat-melted rubber hot melt adhesive and the porous substrate are pressure-bonded. As a result, the heat-melted rubber-based hot melt adhesive is brought into close contact with the porous substrate by its cohesive force (adhesive force), and the heat-melted rubber-based hot melt adhesive is put into the pores of the porous substrate. Let it flow. Thereafter, the porous base material is bonded by cooling and solidifying the rubber-based hot melt adhesive.

  On the other hand, tissues made of natural materials such as cellulosic materials and cotton materials, and non-woven fabrics that have been subjected to hydrophilic treatment are hydrophilic porous substrates. The surface of such a hydrophilic porous substrate is highly polar, whereas rubber hot melt adhesive has low polarity, so the affinity between the hydrophilic porous substrate and rubber hot melt adhesive is low. The nature is low. For this reason, even when a hot melted rubber-based hot melt adhesive and a hydrophilic porous substrate are pressure-bonded, the rubber-based hot melt adhesive hardly flows into the pores of the hydrophilic porous substrate. Since the contact area between the hot melt adhesive and the hydrophilic porous substrate is reduced, the adhesion action due to intermolecular force or anchor effect is reduced. In such a case, when the hydrophilic porous substrate is dry, an adhesive strength that can withstand practical use can be obtained, but when the hydrophilic porous substrate is wetted by body fluid such as urine and becomes wet. The adhesive strength is significantly reduced. Therefore, it is necessary for rubber-based hot melt adhesives to improve wet adhesion in order to maintain excellent adhesive strength even with a hydrophilic porous substrate in a wet state. ing.

  Therefore, Patent Document 2 discloses a hot melt adhesive further including a wax modified with a carboxylic acid and / or a carboxylic acid anhydride in addition to the styrene block copolymer. According to the wax modified with carboxylic acid and / or carboxylic anhydride, it is possible to impart polarity to the hot melt adhesive, thereby increasing the affinity of the hot melt adhesive to the hydrophilic porous substrate, It becomes possible to improve the wet adhesion of the hot melt adhesive.

  However, the wax modified with carboxylic acid and / or carboxylic anhydride has low compatibility with other components contained in the hot melt adhesive. For this reason, when a wax modified with a carboxylic acid and / or a carboxylic acid anhydride is used, the thermal stability of the hot melt adhesive is lowered. Hot melt adhesives with low thermal stability cause gelation and carbonization when heated and melted, resulting in reduced coatability and adhesive strength.

  Further, the wax modified with carboxylic acid and / or carboxylic acid anhydride has unreacted free acid remaining. Therefore, when a wax modified with carboxylic acid and / or carboxylic anhydride is used, the hot melt adhesive generates an unpleasant odor. Such a hot-melt adhesive gives discomfort to workers when assembling disposable products and users of disposable products. Therefore, it is not desirable to use waxes modified with carboxylic acids and / or carboxylic anhydrides.

JP 2005-104996 A Japanese Patent No. 4848184

  Therefore, the present invention provides a hot melt with improved wet adhesion to components such as polyolefin resin films, non-woven fabrics, tissues, and natural rubber without lowering thermal stability and generating odors. An object is to provide an adhesive.

  The hot melt adhesive of the present invention includes a block copolymer of a vinyl aromatic hydrocarbon and a conjugated diene compound and a thermoplastic block copolymer (A) containing at least one of hydrogenated products thereof, and unsaturated It contains an acid-modified petroleum resin (B) that is acid-modified with a carboxylic acid or an anhydride thereof.

(Thermoplastic block copolymer (A))
The hot melt adhesive of the present invention contains a thermoplastic block copolymer (A). Examples of the thermoplastic block copolymer (A) include a block copolymer obtained by copolymerizing a vinyl aromatic hydrocarbon and a conjugated diene compound, and a hydrogenated product thereof. The thermoplastic block copolymer (A) contains at least one of the block copolymer and its hydrogenated product, and may consist of at least one of the block copolymer and its hydrogenated product. preferable.

  The vinyl aromatic hydrocarbon means an aromatic hydrocarbon compound having a vinyl group in the molecule. Specific examples of vinyl aromatic hydrocarbons include styrene, t-butyl styrene, o-methyl styrene, p-methyl styrene, divinyl benzene, p-tert-butyl styrene, 1,3-dimethyl styrene, α-methyl styrene. Vinyl naphthalene, vinyl anthracene, 1,1-diphenyl styrene, and N, N-diethyl-p-aminoethyl styrene. A vinyl aromatic hydrocarbon may be used individually by 1 type, and 2 or more types may be used together. Of these, styrene is preferred as the vinyl aromatic hydrocarbon.

  The conjugated diene compound means a compound having a conjugated double bond in the molecule. Specific examples of the conjugated diene compound include 1,3-butadiene, 2-methyl-1,3-butadiene (isoprene), 2,3-dimethyl-1,3-butadiene, 1,3-pentadiene, 1,3. -Hexadiene can be exemplified. A conjugated diene compound may be used individually by 1 type, and 2 or more types may be used together. Of these, 1,3-butadiene and 2-methyl-1,3-butadiene (isoprene) are particularly preferable.

  The thermoplastic block copolymer (A) may be a hydrogenated block copolymer obtained by copolymerizing a vinyl aromatic hydrocarbon and a conjugated diene compound. A hydrogenated product is a block copolymer of a vinyl aromatic hydrocarbon and a conjugated diene compound, in which all or part of the conjugated double bond derived from the conjugated diene compound is hydrogenated to be converted into a saturated hydrocarbon bond. Means something.

  The content of the vinyl aromatic hydrocarbon component in the thermoplastic block copolymer (A) is preferably 10 to 50% by weight, and more preferably 15 to 35% by weight. When the content of the vinyl aromatic hydrocarbon component is too small, the cohesive force of the hot melt adhesive is lowered, and therefore the wet adhesiveness may be lowered. When there is too much content of a vinyl aromatic hydrocarbon component, there exists a possibility that the solidification rate of the hot-melt-adhesive hot-melted may become too quick. A hot melt adhesive that has a too fast solidification rate has low wet adhesion due to a decrease in permeability to the porous base.

  It is preferable that the block copolymer obtained by copolymerizing a vinyl aromatic hydrocarbon and a conjugated diene compound and the hydrogenated product thereof are not acid-modified with an unsaturated carboxylic acid or an anhydride thereof. Therefore, the block copolymer and the hydrogenated product thereof preferably have neither a carboxyl group (—COOH) nor a carboxylic anhydride group (—CO—O—CO—) in the molecule. By using a block copolymer that is not acid-modified and its hydrogenated product, the generation of odor of the hot-melt adhesive can be greatly reduced.

  Specific examples of the thermoplastic block copolymer (A) include block copolymers such as styrene-isoprene-styrene block copolymer (SIS) and styrene-butadiene-styrene block copolymer (SBS). Hydrogenated; styrene-butadiene / butylene-styrene block copolymer (SBBS), styrene-ethylene / butylene-styrene block copolymer (SEBS), styrene-ethylene / propylene-styrene block copolymer (SEPS), and Examples thereof include hydrogenated products such as styrene-ethylene-ethylene / propylene-styrene block copolymer (SEEPS). These thermoplastic block copolymers (A) may be used individually by 1 type, and 2 or more types may be used together.

  The weight average molecular weight of the thermoplastic block copolymer (A) is preferably 50,000 to 300,000, more preferably 70,000 to 250,000, and particularly preferably 100,000 to 200,000. In the case of a styrene-isoprene-styrene block copolymer having a weight average molecular weight (Mw) that is too small, the cohesive force of the hot-melt adhesive is lowered, and therefore wet adhesion may be lowered. Moreover, in the case of a styrene-isoprene-styrene block copolymer having an excessively large weight average molecular weight (Mw), there is a possibility that the coatability of the hot melt adhesive is lowered.

  In addition, in this invention, the weight average molecular weight of a thermoplastic block copolymer (A) means the measured value obtained by converting with standard polystyrene using a gel permeation chromatography measuring apparatus.

  A commercially available product can be used as the thermoplastic block copolymer (A). Commercially available products include, for example, trade names “Asaprene T-432” manufactured by Asahi Kasei Chemicals Corporation, trade names “Asaprene T-436” manufactured by Asahi Kasei Chemicals Corporation, C. Y. The product name “YH-791” manufactured by the company, the product name “D-1161” manufactured by Kraton, the product name “G-1650” manufactured by Kraton, and the product name “Septon S2002” manufactured by Kuraray are included.

(Acid-modified petroleum resin (B))
The hot melt adhesive of the present invention contains an acid-modified petroleum resin (B) that is acid-modified with unsaturated carboxylic acids or anhydrides thereof. The acid-modified petroleum resin (B) has at least one polar group among a carboxyl group (—COOH) and a carboxylic anhydride group (—CO—O—CO—) in the molecule. The acid-modified petroleum resin (B) may have either one or both of a carboxyl group and a carboxylic anhydride group. Moreover, only 1 type may be used for an acid-modified petroleum resin (B), and it may use 2 or more types together.

  According to the acid-modified petroleum resin (B), the affinity of the hot melt adhesive for the hydrophilic porous substrate can be improved. Such a hot-melt adhesive tends to flow into the pores of the hydrophilic porous substrate when heated and melted. Therefore, the contact area between the hot melt adhesive and the hydrophilic porous substrate can be improved by pressure-bonding the hydrophilic porous substrate to the hot melt adhesive that has been heated and melted. Therefore, the hot-melt adhesive can exhibit excellent adhesive strength to the hydrophilic porous substrate, and such excellent adhesive strength when the hydrophilic porous substrate becomes wet. Even it can be maintained.

  In addition, the acid-modified petroleum resin (B) is excellent in compatibility with other components, and therefore it is possible to improve the thermal stability of the hot melt adhesive.

  The acid-modified petroleum resin (B) can be obtained by acid-modifying an unmodified petroleum resin with an unsaturated carboxylic acid or an anhydride thereof.

  Examples of the unmodified petroleum resin include petroleum resins such as C5 petroleum resins, C9 petroleum resins, C5C9 petroleum resins and dicyclopentadiene petroleum resins, and hydrogenated products of these petroleum resins.

  Examples of unsaturated carboxylic acids or anhydrides thereof include acrylic acid, methacrylic acid, crotonic acid, cinnamic acid, maleic acid, fumaric acid, itaconic acid, citraconic acid, tetrahydrophthalic acid, and acid anhydrides thereof. .

  A commercially available product can be used as the acid-modified petroleum resin (B). As a commercial item, the brand name "CX495" by Nippon Zeon Co., Ltd. and the brand name "JH3100" by Jinhai are mentioned, for example.

  The softening point of the acid-modified petroleum resin (B) is preferably 80 to 130 ° C, more preferably 80 to 120 ° C, and particularly preferably 90 to 120 ° C. If the acid-modified petroleum resin (B) has a softening point that is too low, the cohesive strength of the hot melt adhesive itself may be reduced and the adhesive strength may be reduced. In the acid-modified petroleum resin (B) whose softening point is too high, there is a possibility that the wet-adhesiveness may be lowered by reducing the permeability of the hot melt adhesive into the pores of the hydrophilic porous substrate.

  In the present invention, the softening point of the acid-modified petroleum resin (B) is a softening point measured by a ring and ball method in accordance with JIS K2207.

  The acid value of the acid-modified petroleum resin (B) is preferably 0.1 to 50 mgKOH / g. The acid value of the acid-modified petroleum resin (B) is a value measured by a method based on ASTM D1308.

  The content of the acid-modified petroleum resin (B) in the hot melt adhesive is preferably 10 to 200 parts by weight, more preferably 50 to 200 parts by weight with respect to 100 parts by weight of the thermoplastic block copolymer (A). 50 to 150 parts by weight are particularly preferable. When there is too little content of acid-modified petroleum resin (B), there exists a possibility that the affinity to the hydrophilic porous base material of a hot-melt-adhesive cannot fully be improved. When there is too much content of acid-modified petroleum resin (B), content of the free acid in a hot-melt-adhesive agent will improve, and there exists a possibility that an odor may generate | occur | produce.

(Unmodified petroleum resin (C))
The hot melt adhesive of the present invention preferably contains an unmodified petroleum resin (C) that is not acid-modified with unsaturated carboxylic acids or anhydrides thereof.

  By using the acid-modified petroleum resin (B) and the unmodified petroleum resin (C) in combination, the generation of odor of the hot melt adhesive can be further reduced and the thermal stability can be further improved.

  Examples of the unmodified petroleum resin (C) include C5 petroleum resins, C9 petroleum resins, C5C9 petroleum resins, dicyclopentadiene petroleum resins, and hydrogenated products thereof. In the hydrogenated product, all of the unsaturated bonds may be hydrogenated, or a part of the unsaturated bonds may be hydrogenated. Only one kind of the unmodified petroleum resin (C) may be used, or two or more kinds may be used in combination.

  The softening point of the unmodified petroleum resin (C) is preferably 80 to 130 ° C, more preferably 90 to 120 ° C. In the case of an unmodified petroleum resin (C) having a softening point that is too low, the cohesive force of the hot melt adhesive itself may be reduced, and the wet adhesiveness may be reduced. In the case of the unmodified petroleum resin (C) whose softening point is too high, there is a possibility that the thermal stability of the hot melt adhesive is lowered.

  In the present invention, the softening point of the unmodified petroleum resin (C) is a softening point measured by a ring and ball method in accordance with JIS K2207.

  A commercially available product can be used as the unmodified petroleum resin. Commercially available products include, for example, the product name “Escollet 5600” manufactured by Tonex, the product name “Marcaclear H” manufactured by Maruzen Petrochemical Co., Ltd., the product name “Clearon K100” manufactured by Yasuhara Chemical Co., Ltd., and the product manufactured by Arakawa Chemical Co., Ltd. The name “Arcon P100”, the product name “Arcon M100” manufactured by Arakawa Chemical Co., Ltd., the product name “Imabe S100” manufactured by Idemitsu Petrochemical Co., Ltd., the product name “Clearon K4090” manufactured by Yasuhara Chemical Co., Ltd. ECR231C ”, trade name“ Rigalite R7100 ”manufactured by Eastman Chemical Co., Ltd., trade name“ Rigalite C6100 ”manufactured by Eastman Chemical Co., etc., and the like.

  Since the content of the unmodified petroleum resin (C) in the hot melt adhesive can improve the wet adhesiveness of the hot melt adhesive, 100 parts by weight of the thermoplastic block copolymer (A), 100 to 300 parts by weight is preferable, 150 to 300 parts by weight is more preferable, and 200 to 300 parts by weight is particularly preferable.

(Plasticizer (D))
The hot melt adhesive of the present invention preferably contains a plasticizer (D). According to the plasticizer (D), the wet adhesion of the hot melt adhesive can be further improved.

Examples of the plasticizer (D) include paraffinic process oil, naphthenic process oil, and process oil such as aromatic process oil. Above all,
Paraffinic process oil and naphthenic process oil are preferred, and paraffinic process oil is more preferred. These plasticizers may be used alone or in combination of two or more.

  The paraffinic process oil is preferably an aliphatic chain hydrocarbon. The carbon number of the aliphatic chain hydrocarbon contained in the paraffinic process oil is not particularly limited, but is preferably 16 to 45.

  100-1500 are preferable and, as for the number average molecular weight (Mn) of paraffin type process oil, 250-1000 are more preferable. If the number average molecular weight (Mn) is too small, the paraffinic process oil may reduce the cohesive strength of the hot melt adhesive and may result in insufficient wet adhesion. Moreover, in the case of paraffinic process oil having a number average molecular weight (Mn) that is too large, the melt viscosity of the hot melt adhesive may be excessively increased, and the coatability of the hot melt adhesive may be reduced.

  Commercially available products can be used as the paraffinic process oil. Commercially available products include, for example, trade name “NA Solvent” manufactured by Nippon Oil and Fats, product name “PW-380” manufactured by Idemitsu Kosan Co., Ltd., product name “Diana Fresia S32” manufactured by Idemitsu Kosan Co., Ltd. “PS-32”, trade name “IP-solvent 2835” manufactured by Idemitsu Petrochemical Co., Ltd., product name “Diana Process Oil PW-90” manufactured by Idemitsu Petrochemical Co., Ltd., trade name “Neothiozole” manufactured by Sanko Chemical Co., Ltd. Is mentioned.

  The naphthenic process oil is preferably an aliphatic cyclic hydrocarbon. The number of carbon atoms of the aliphatic cyclic hydrocarbon contained in the naphthenic process oil is preferably 3 or more.

  The number average molecular weight (Mn) of the naphthenic process oil is preferably 100-1500, and more preferably 250-1000. A naphthenic process oil having a number average molecular weight (Mn) that is too small may reduce the cohesive strength of the hot melt adhesive, resulting in insufficient wet adhesion of the hot melt adhesive. In addition, in the case of a naphthenic process oil having a number average molecular weight (Mn) that is too large, the melt viscosity of the hot melt adhesive may be excessively increased and the coatability of the hot melt adhesive may be reduced.

  A commercially available product can be used as the naphthenic process oil. Examples of commercially available products include “Diana Fresia N28” manufactured by Idemitsu Kosan Co., Ltd., “Diana Fresia U46” manufactured by Idemitsu Kosan Co., Ltd., “Diana Process Oil NR” manufactured by Idemitsu Kosan Co., Ltd., Shell Chemical Co., Ltd. The product name “Shelf Rex 371N” is available.

  In the present invention, the number average molecular weight (Mn) of the paraffinic process oil and the naphthenic process oil is a measured value obtained by conversion with standard polystyrene using a gel permeation chromatography measuring device, respectively. means.

  As content of the plasticizer (D) in a hot-melt-adhesive, 25-250 weight part is preferable with respect to 100 weight part of thermoplastic block copolymers (A), and 50-150 weight part is more preferable. With a hot melt adhesive in which the content of the plasticizer (D) is too high, there is a possibility that the creep resistance is lowered, or the cohesive force is lowered and the wet adhesiveness is lowered. Moreover, in the hot melt adhesive in which the content of the plasticizer (D) is too low, the solidification rate after heating and melting becomes too high, and the adhesiveness, particularly wet adhesiveness, may be lowered.

(Wax (E))
The hot melt adhesive of the present invention preferably contains a wax (E). According to the wax (E), the wet adhesiveness of the hot melt adhesive can be further improved.

  Examples of the wax (E) include animal waxes such as shellac wax and beeswax; plant waxes such as carnauba wax and beeswax; mineral waxes such as paraffin wax and macrocrystalline wax; polyethylene wax, polypropylene wax, Examples include polyolefin waxes such as ethylene-vinyl acetate copolymer waxes, synthetic waxes such as Fischer-Tropsch waxes, among others, improving wet adhesion to polyolefin resin films and reducing thermal stability. From the viewpoint of reducing odor generation, polyolefin waxes are preferred, and ethylene-vinyl acetate copolymer (EVA) waxes are more preferred.

  The polyolefin wax refers to an olefin polymer having a number average molecular weight of 10,000 or less and containing an olefin component in excess of 50% by weight. The olefin polymer is mainly composed of an olefin homopolymer, an olefin copolymer, a copolymer of an olefin and a monomer copolymerizable with the olefin, and an olefin homopolymer or an olefin copolymer. It includes a graft copolymer having a chain and a molecular chain composed of a monomer copolymerizable with an olefin in the main chain. Examples of the monomer copolymerizable with olefin include vinyl acetate and maleimide. The ethylene-vinyl acetate copolymer wax includes not only an ethylene-vinyl acetate copolymer wax but also a graft copolymer wax in which a molecular chain composed of vinyl acetate is branched in a polyethylene main chain. Since the wax (E) can further suppress the generation of odor, it is preferable that the wax (E) is not modified with a carboxylic acid or an acid anhydride.

  In the present invention, the melting point of the wax (E) is preferably 60 to 120 ° C. The melting point of the wax (E) can be measured by a method based on ASTM D127. When the melting point of the wax (E) exceeds 120 ° C., the hot melt adhesive becomes hard and the wet adhesive property of the hot melt adhesive may be reduced. Moreover, when the melting point of the wax (E) is less than 60 ° C., the cohesive force of the hot melt adhesive is lowered, and the wet adhesive property of the hot melt adhesive may be lowered.

  As the wax (E), a commercially available product can be used. Commercially available polyolefin waxes include Honeywell's product name “A-C8” (polyethylene wax), INNOSPEC product name “VISCOWAX 122” (polyethylene wax), Honeywell's product name “A-C400”. "(Ethylene-vinyl acetate copolymer wax), trade name" VISCOWAX 334 "(ethylene-vinyl acetate copolymer wax) manufactured by INNOSPEC," VISCOWAX 343 "(ethylene-vinyl acetate copolymer wax manufactured by INNOSPEC) ) And the like.

  As content of wax (E) in a hot-melt-adhesive, 5-50 weight part is preferable with respect to 100 weight part of thermoplastic block copolymers (A), and 10-30 weight part is more preferable. When the content of the wax (E) is too high, the hot melt adhesive becomes hard, and the wet adhesiveness of the hot melt adhesive may be reduced. Moreover, when content of wax (E) is too low, there exists a possibility that the wet adhesiveness of the hot-melt-adhesive with respect to polyolefin resin may fall.

  In addition, in order to improve the wet adhesiveness with respect to a polyolefin-type resin film and to suppress an odor more, it is preferable that a hot-melt-adhesive contains a polyolefin-type wax and process oil.

(Other ingredients)
The hot melt adhesive of the present invention preferably contains an antioxidant. Antioxidants include 2,6-di-t-butyl-4-methylphenol, n-octadecyl-3- (4′-hydroxy-3 ′, 5′-di-t-butylphenyl) propionate, 2, 2′-methylenebis (4-methyl-6-tert-butylphenol), 2,2′-methylenebis (4-ethyl-6-tert-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)] acrylate, tetrakis [methylene-3- ( , 5-di-tert-butyl-4-hydroxyphenyl) propionate] hindered phenolic antioxidants such as methane; dilauryl thiodipropionate, lauryl stearyl thiodipropionate, pentaerythritol tetrakis (3-laurylthiopro) Sulfur-based antioxidants such as Pionate; and phosphorus-based antioxidants such as Tris (nonylphenyl) phosphite and Tris (2,4-di-t-butylphenyl) phosphite. An antioxidant may be used individually by 1 type and may use 2 or more types together.

  The hot melt adhesive of the present invention may contain an ultraviolet absorber. Examples of the ultraviolet absorber include 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 ultraviolet absorbers; 2-hydroxy-4-methoxybenzophenone and other benzophenone ultraviolet absorbers; salicylic acid ester Examples include ultraviolet absorbers, cyanoacrylate ultraviolet absorbers; hindered amine light stabilizers. An ultraviolet absorber may be used individually by 1 type, and may use 2 or more types together.

  The hot melt adhesive of the present invention may contain liquid rubber. Examples of the liquid rubber include liquid polybutene, liquid polybutadiene, liquid polyisoprene, and hydrogenated resins thereof. A liquid rubber may be used individually by 1 type, and may use 2 or more types together.

  As a method of bonding two adherends using the hot melt adhesive of the present invention, for example, the following method is used. First, the hot melt adhesive is heated to a molten state. Next, a hot melt adhesive in a molten state is applied to one adherend. And after laminating the other adherend on one adherend, the hot melt adhesive is cooled and solidified, whereby two adherends can be bonded.

  The method for applying the hot-melt adhesive melted by heating is not particularly limited, and a known method is used. Examples thereof include slot coater coating, roll coater coating, spiral coating, omega coating, control seam coating, slot spray coating, curtain spray coating, and dot coating.

  The hot melt adhesive of the present invention is suitably used for the production of disposable products. Although it does not specifically limit as a disposable product, For example, what is called hygiene materials, such as a paper diaper, a sanitary napkin, a pet sheet, a hospital gown, and a lab coat, etc. are mentioned.

  The hot melt adhesive of the present invention has improved wet adhesiveness with almost no decrease in thermal stability or generation of odor.

  Hereinafter, the present invention will be described more specifically with reference to examples, but the present invention is not limited thereto.

  In Examples and Comparative Examples to be described later, for each of the thermoplastic block copolymer, acid-modified petroleum resin, unmodified petroleum resin, and plasticizer, antioxidant, and wax used in the production of the hot melt adhesive, Detailed description is given in.

Thermoplastic block copolymer:
Styrene-isoprene-styrene (SIS) block copolymer (A1) [styrene component content 16% by weight, weight average molecular weight (Mw) 171,000, manufactured by Nippon Zeon Co., Ltd., product name “Quintac 3433N”]
Styrene-butadiene-styrene (SBS) block copolymer (A2) [styrene component content 30% by weight, weight average molecular weight (Mw) 122,300, manufactured by Asahi Kasei Chemicals Corporation, product name “Asaprene T-436”]
Styrene-butadiene / butylene-styrene (SBBS) block copolymer (A3) [styrene content 30% by weight, weight average molecular weight (Mw) 100,000, manufactured by Asahi Kasei Chemicals Corporation, product name “Tuftec P1500”]
Styrene-ethylene / propylene-styrene (SEPS) block copolymer (A4) [styrene content 30% by weight, weight average molecular weight (Mw) 55,000, manufactured by Kuraray Co., Ltd., product name “Septon 2002”]
Styrene-ethylene / butylene-styrene (SEBS) block copolymer (A5) [styrene content 30% by weight, weight average molecular weight (Mw) 200,000, manufactured by Asahi Kasei Chemicals Corporation, product name “Tuftec H1041”]
-Maleic acid-modified styrene-ethylene / butylene-styrene (SEBS) block copolymer [trade name “Tuftec M1913” manufactured by Asahi Kasei Corporation]

Acid-modified petroleum resin:
Acid-modified petroleum resin (B1) that is acid-modified with maleic acid [softening point 100 ° C., acid value 1.8 mgKOH / g, trade name “Quintac CX495” manufactured by Nippon Zeon Co., Ltd.]

Unmodified petroleum resin:
Unmodified petroleum resin (C1) [hydrogenated derivative of aliphatic petroleum hydrocarbon resin, softening point 100 ° C., product name “Arkon M-100” manufactured by Arakawa Chemical]
Unmodified petroleum resin (C2) [hydrogenated derivative of aliphatic petroleum hydrocarbon resin, softening point 80 ° C., product name “E5380” manufactured by General]
Unmodified petroleum resin (C3) [hydrogenated derivative of aliphatic petroleum hydrocarbon resin, softening point 120 ° C., product name “Imabe P120” manufactured by Idemitsu Kosan Co., Ltd.]

Plasticizer:
Paraffinic process oil (D1) (number average molecular weight (Mn) 980, aliphatic chain hydrocarbon, product name “Diana Process Oil PW-90” manufactured by Idemitsu Oil Co., Ltd.)
・ Naphthenic process oil (D2) (number average molecular weight (Mn) 100-1500, aliphatic cyclic hydrocarbon, product name “Shellex 371N” manufactured by Shell Chemical Co., Ltd.)

Antioxidant:
Phenol-based antioxidant (product name “IRGANOX1010” manufactured by BASF)

wax:
Ethylene-vinyl acetate copolymer (EVA) wax (E1) (melting point: 92 ° C., product name “A-C400” manufactured by Honeywell)
Polyethylene (PE) wax (E2) (melting point 113 ° C., product name “A-C8” manufactured by Honeywell)
Acid-modified polyethylene (PE) wax (E3) acid-modified with carboxylic acid anhydride (melting point 104 ° C., product name “Viscowax261” manufactured by Innospec)

(Examples 1-16 and Comparative Examples 1-3)
SIS block copolymer (A1), SBS block copolymer (A2), SBBS block copolymer (A3), SEPS block copolymer (A4), SEBS block copolymer (A5), malee, respectively Acid-modified SEBS block copolymer, acid-modified petroleum resin (B1), unmodified petroleum resins (C1) to (C3), paraffinic process oil (D1), naphthenic process oil (D2), phenolic antioxidant, After the EVA wax (E1), the PE wax (E2), and the acid-modified PE wax (E3) were added in the mixing amounts shown in Tables 1 and 2, respectively, into a stirring kneader equipped with a heating device, A hot melt adhesive was produced by kneading while heating at 145 ° C. for 90 minutes.

(Evaluation)
The hot melt adhesive was evaluated for adhesiveness, wet adhesiveness, thermal stability, and odor according to the following procedure. These results are shown in Tables 1 and 2. About the adhesiveness (nonwoven fabric / PE film) and wet adhesiveness (nonwoven fabric / PE film), only the hot melt adhesives of Examples 12 to 16 were measured.

(Adhesion: Tissue / Tissue)
After the hot melt adhesive was melted by heating to 140 ° C., it was applied to tissue paper at a coating amount of 3 g / m ² by spiral spray. One second after application, another tissue paper was laminated on the tissue paper. Thereafter, these were pressed and pressure-bonded at 23 ° C. and a pressure of 50 gf / cm ² (4903 Pa) for 0.01 seconds to obtain a laminate. By cutting this laminate, a strip-shaped test piece having a width of 20 mm and a length of 150 mm was obtained.

Next, the test piece was stored for 24 hours in an atmosphere of 23 ° C. and 50% relative humidity to cool and solidify the hot melt adhesive. About this test piece, based on JISK6854, the adhesive strength [* 10 ^<-2 > N / 20mm] was measured by performing a T-type peeling test by the tensile rate of 100 mm / min. The obtained adhesive strength is shown in the column of “Adhesiveness (tissue / tissue)” in Table 1.

(Wet adhesion: tissue / tissue)
After the hot melt adhesive was melted by heating to 140 ° C., it was applied to tissue paper at a coating amount of 3 g / m ² by spiral spray. One second after application, another tissue paper was laminated on the tissue paper. Thereafter, these were pressed and pressure-bonded at 23 ° C. and a pressure of 50 gf / cm ² (4903 Pa) for 0.01 seconds to obtain a laminate. By cutting this laminate, a strip-shaped test piece having a width of 20 mm and a length of 150 mm was obtained.

Next, the test piece was stored in an atmosphere at 23 ° C. and 50% relative humidity for 24 hours to cool and solidify the hot melt adhesive, and then immersed in water at 23 ° C. for 1 minute. Then, the test piece was taken out from water and the wet test piece was obtained by wiping off water. Then, the adhesive strength [× 10 ⁻² N / 20 mm] was measured by performing a T-type peeling test on the wet specimen in accordance with JIS K6854 at a tensile speed of 100 mm / min. The obtained adhesive strength is shown in the column of “Wet adhesiveness (tissue / tissue)” in Table 1.

(Adhesiveness: non-woven fabric / PE film)
After the hot melt adhesive was melted by heating to 140 ° C., it was applied to the nonwoven fabric at a coating width of 1 mm and intervals of 2 mm by slot coater coating at a coating amount of 15 g / m ² . One second after application, a PE film was laminated on the nonwoven fabric. Thereafter, these were pressed and pressure-bonded at 23 ° C. and a pressure of 50 gf / cm ² (4903 Pa) for 0.01 seconds to obtain a laminate. By cutting this laminate, a strip-shaped test piece having a width of 20 mm and a length of 150 mm was obtained.

Next, the test piece was stored for 2 weeks in an atmosphere of 50 ° C. and 80% relative humidity to cure the hot melt adhesive. About this test piece, based on JISK6854, the adhesive strength [* 10 ^<-2 > N / 20mm] was measured by performing a T-type peeling test by the tensile rate of 100 mm / min. The obtained adhesive strength is shown in the column of “Adhesiveness (nonwoven fabric / PE film)” in Table 1.

(Wet adhesion: Nonwoven fabric / PE film)
After the hot melt adhesive was melted by heating to 140 ° C., it was applied to the nonwoven fabric at a coating width of 1 mm and intervals of 2 mm by slot coater coating at a coating amount of 15 g / m ² . One second after application, a PE film was laminated on the nonwoven fabric. Thereafter, these were pressed and pressure-bonded at 23 ° C. and a pressure of 50 gf / cm ² (4903 Pa) for 0.01 seconds to obtain a laminate. By cutting this laminate, a strip-shaped test piece having a width of 20 mm and a length of 150 mm was obtained.

Next, the test piece was stored in an atmosphere of 50 ° C. and 80% relative humidity for 2 weeks to cure the hot melt adhesive, and then immersed in water at 23 ° C. for 1 minute. Then, the test piece was taken out from water and the wet test piece was obtained by wiping off water. Then, the adhesive strength [× 10 ⁻² N / 20 mm] was measured by performing a T-type peeling test on the wet specimen in accordance with JIS K6854 at a tensile speed of 100 mm / min. The obtained adhesive strength is shown in the column of “Wet adhesiveness (nonwoven fabric / PE film)” in Table 1.

(Thermal stability 1)
After the hot melt adhesive was melted by heating to 140 ° C., the color degree of the hot melt adhesive was measured according to the color test method for chemical products defined in JIS K0071, and the Gardner color number was measured. Next, 20 g of the hot melt adhesive is put in a glass bottle, put in a hot air dryer at 190 ° C. without covering the glass bottle, heated for 72 hours, and then the coloring degree of the hot melt adhesive is measured according to JIS K0071. The Gardner color number was measured according to the color test method for chemical products specified in 1. Table 1 shows the difference in the number of Gardner colors before and after heating at 190 ° C.

(Thermal stability 2)
50 g of hot melt adhesive dissolved by heating to 140 ° C. is put in a glass bottle, and then put in a hot air dryer at 190 ° C. without heating the glass bottle and heated for one week. The hot melt adhesive before and after heating at 190 ° C. was visually confirmed to check for the occurrence of gelation and carbonization. In Table 1, “good” and “bad” are as follows.
“Good”: Neither gelation nor carbonization occurred.
“Bad”: At least one of gelation and carbonization occurred.

(Odor)
35 g of hot melt adhesive was placed in a 70 mL glass bottle, and a polymer lid was placed on the glass bottle. Next, the hot melt adhesive was heated and melted by heating the glass bottle. Thereafter, the lid was removed from the glass bottle, and the occurrence of odor of the hot melt adhesive was determined by sensory evaluation. In Table 1, “good”, “possible”, and “bad” are as follows.
“Good”: Almost no odor was felt.
“OK”: Some odor was felt.
“Bad”: The odor was clearly felt.

The hot melt adhesive of the present invention is 100 parts by weight of a thermoplastic block copolymer (A) containing at least one of a block copolymer of a vinyl aromatic hydrocarbon and a conjugated diene compound and a hydrogenated product thereof , 100 to 300 parts by weight of an acid-modified petroleum resin (B) that is acid-modified with an unsaturated carboxylic acid or an anhydride thereof, and an unmodified petroleum resin (C) that is not acid-modified with an unsaturated carboxylic acid or an anhydride thereof It is characterized by including.

(Unmodified petroleum resin (C))
The hot melt adhesive of the present invention contains an unmodified petroleum resin (C) that is not acid-modified with unsaturated carboxylic acids or anhydrides thereof.

Since the content of the unmodified petroleum resin (C) in the hot melt adhesive can improve the wet adhesiveness of the hot melt adhesive, 100 parts by weight of the thermoplastic block copolymer (A), It is limited to 100 to 300 parts by weight, preferably 150 to 300 parts by weight, and more preferably 200 to 300 parts by weight.

Claims (9)

  Acid-modified by block copolymer of vinyl aromatic hydrocarbon and conjugated diene compound and thermoplastic block copolymer (A) containing at least one of hydrogenated products thereof, and unsaturated carboxylic acids or anhydrides thereof The hot-melt-adhesive characterized by including the acid-modified petroleum resin (B) formed.   The hot melt adhesive according to claim 1, wherein the content of the acid-modified petroleum resin (B) is 10 to 200 parts by weight with respect to 100 parts by weight of the thermoplastic block copolymer (A). .   The hot-melt adhesive according to claim 1 or 2, which contains an unmodified petroleum resin (C) that has not been acid-modified with unsaturated carboxylic acids or anhydrides thereof.   The hot melt adhesive according to claim 3, wherein the content of the unmodified petroleum resin (C) is 100 to 300 parts by weight with respect to 100 parts by weight of the thermoplastic block copolymer (A). .   The hot melt adhesive according to any one of claims 1 to 4, further comprising a plasticizer (D).   The hot melt adhesive according to claim 1, comprising a wax (E).   The hot melt adhesive according to claim 6, wherein the wax (E) contains a polyolefin wax.   The hot melt adhesive according to claim 7, wherein the polyolefin wax contains a vinyl acetate component.   A disposable product comprising the hot melt adhesive according to any one of claims 1 to 8.