Hot melt adhesive, laminate and disposable product

Abstract

To provide a hot-melt adhesive excellent in adhesive properties, having excellent feeling, and suppressed in tack feeling.SOLUTION: A hot-melt adhesive which contains a styrenic block copolymer (A) and a liquid plasticizer (B) has at least one endothermic peak in a range of 45-80°C and at least one endothermic peak in a range of 95-130°C in a DSC curve obtained when a temperature is raised at a speed of 10°C / minute by a differential scanning calorimeter (DSC).SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a hot melt adhesive, a laminate, and a disposable product.

Background Art

[0002] Conventionally, disposable products such as paper diapers and sanitary napkins have used constituent members such as non-woven fabrics, porous substrates (for example, tissues, etc.), polyolefin-based resin films, and natural rubbers.

[0003] These disposable products are assembled by adhering these constituent members using a hot melt adhesive.

[0004] In recent years, disposable products have become thinner, and accordingly, thinner porous substrates have been used.

[0005] When a conventional hot melt adhesive is applied to a thinner porous substrate, if the hot melt adhesive oozes out from the porous substrate even slightly due to heat, pressure, etc., since the hot melt adhesive itself has adhesiveness, there is a risk of giving discomfort to the user during wearing.

[0006] In order to reduce the tackiness (stickiness) on the surface of the hot melt adhesive, a method of incorporating a solid plasticizer into the hot melt adhesive is known.

[0007] For example, Patent Document 1 describes a hot melt adhesive suitable for elastic attachment adhesion of disposable products that can be applied at a relatively low temperature in the range of about 110 to 130°C.

[0008] Patent Document 2 describes a hot melt adhesive containing a polyethylene polymer by a metallocene catalyst, a styrene-based block copolymer, a tackifying resin, and a solid plasticizer.

Prior Art Documents

Patent Documents

[0009] [Patent Document 1] Japanese Patent Publication No. 2014-508832 [Patent Document 2] Japanese Unexamined Patent Application Publication No. 2017-206701 [Summary of the Invention] [Problems to be Solved by the Invention]

[0010] The low application temperature hot melt adhesive described in Patent Document 1 could not achieve both suppression of tackiness and good texture because the blending ratio of the solid plasticizer was not appropriate.

[0011] The polyolefin-based hot melt adhesive of Patent Document 2 contains a polyolefin polymer by a metallocene catalyst, a styrene-ethylene-butylene-styrene block copolymer (SEBS), a tackifier, and a solid plasticizer, but does not contain a liquid plasticizer, so there is a problem that the texture deteriorates and the adhesiveness is not exhibited.

[0012] In order to suppress the tackiness, it is necessary to contain a certain amount of solid plasticizer in the hot melt adhesive, but the open time of the hot melt adhesive becomes short, and sufficient adhesive strength may not be exhibited after bonding to the adherend. Furthermore, when the content of the solid plasticizer increases, the hot melt adhesive itself becomes hard, which may cause deterioration of the texture of disposable products. Although it is desired to provide a hot melt adhesive that can improve these problems of the prior art, it has not yet been developed.

[0013] In view of the above circumstances, an object of the present invention is to provide a hot melt adhesive having excellent adhesiveness, good texture, and suppressed tackiness. [Means for Solving the Problems]

[0014] As a result of intensive research to achieve the above object, the present inventors have found that the above problems can be solved by a hot-melt adhesive containing a styrene block copolymer (A) and a liquid plasticizer (B) and having specific physical property values. The present invention has been further studied and completed by the present inventors.

[0015] That is, the present invention provides an invention in the following aspects. Item 1. A hot-melt adhesive containing a styrene block copolymer (A) and a liquid plasticizer (B), In the DSC curve obtained when the temperature is raised at a rate of 10 ° C. / min by differential scanning calorimetry (DSC), it has at least one endothermic peak in the range of 45 to 80 ° C. and at least one endothermic peak in the range of 95 to 130 ° C., characterized by the above. Item 2. The hot-melt adhesive according to Item 1, further containing a tackifier resin (C) and a solid plasticizer (D). Item 3. The hot-melt adhesive according to Item 2, wherein the solid plasticizer (D) contains a solid plasticizer (D1) having a melting point in the range of 57 to 80 ° C. and a solid plasticizer (D2) having a melting point in the range of 95 to 141 ° C. Item 4. The content of the solid plasticizer (D1) is 30 to 150 parts by mass with respect to 100 parts by mass of the styrene block copolymer (A), The hot-melt adhesive according to Item 3, wherein the content of the solid plasticizer (D2) is 5 to 40 parts by mass with respect to 100 parts by mass of the styrene block copolymer (A). Item 5. The hot-melt adhesive according to any one of Items 1 to 4, wherein the styrene block copolymer (A) contains at least one of a styrene-butadiene-styrene block copolymer (SBS) and a styrene-isoprene-styrene block copolymer (SIS). Item 6. The hot melt adhesive according to any one of items 2 to 5, wherein the solid plasticizer (D) contains at least one selected from the group consisting of paraffin wax, polyethylene wax, polypropylene wax, and Fischer-Tropsch wax. Item 7. A laminate in which a pair of base materials are joined together by the hot melt adhesive according to any one of items 1 to 6. Item 8. A disposable product using the laminate according to item 7.

Effect of the Invention

[0016] The hot melt adhesive of the present invention is excellent in adhesiveness, has a good texture, and has a suppressed tackiness.

Brief Description of the Drawings

[0017]

Figure 1

Modes for Carrying Out the Invention

[0018] Hereinafter, preferred embodiments of the present invention will be described in detail. The description of the constituent elements described below may be based on representative embodiments and specific examples, but the present invention is not limited to such embodiments.

[0019] In this specification, a numerical range represented by "~" means a range including the numerical values described before and after "~" as the lower limit value and the upper limit value.

[0020] In this specification, "a and / or b" means a alone, b alone, and the three of a and b.

[0021] 1. Hot melt adhesive The hot melt adhesive of the present invention contains, as essential components, a styrenic block copolymer (A) and a liquid plasticizer (B). The hot melt adhesive of the present invention has at least one endothermic peak in the range of 45 to 80 °C and at least one endothermic peak in the range of 95 to 130 °C in the DSC curve obtained when the temperature is raised at a rate of 10 °C / min by differential scanning calorimetry (DSC).

[0022] The method for measuring the endothermic peak using DSC will be described later in the items of the examples.

[0023] Since the hot melt adhesive of the present invention satisfies the above-described requirements, it has excellent adhesiveness, a good texture, and suppressed tackiness.

[0024] Hereinafter, each component contained in the hot melt adhesive of the present invention will be described. Note that the hot melt adhesive of the present invention may sometimes be simply referred to as "the present invention".

[0025] (Styrenic block copolymer (A)) In the present invention, the styrenic block copolymer (A) is a block copolymer of a vinyl aromatic hydrocarbon and a conjugated diene compound.

[0026] The vinyl aromatic hydrocarbon means an aromatic hydrocarbon compound having a vinyl group. Examples of the vinyl aromatic hydrocarbon include styrene, o-methylstyrene, p-methylstyrene, p-tert-butylstyrene, 1,3-dimethylstyrene, α-methylstyrene, vinylnaphthalene, vinylanthracene, and the like. These vinyl aromatic hydrocarbons can be used alone or in combination of two or more. Among these vinyl aromatic hydrocarbons, styrene is preferred.

[0027] The conjugated diene compound means a diolefin compound having at least one pair of conjugated double bonds. 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, and the like. These conjugated diene compounds can be used alone or in combination of two or more. Among these conjugated diene compounds, 1,3-butadiene and isoprene are preferred.

[0028] The styrenic block copolymer (A) may be an unhydrogenated product or a hydrogenated product. Examples of the styrenic block copolymer (A) include styrene-butadiene-styrene block copolymer (SBS), styrene-isoprene-styrene block copolymer (SIS), styrene-ethylene-butylene-styrene block copolymer (SEBS), styrene-butadiene-butylene-styrene block copolymer (SBBS), and styrene-ethylene-propylene-styrene block copolymer (SEPS). These styrenic block copolymers (A) can be used alone or in combination of two or more. Among these styrenic block copolymers (A), from the viewpoint of the texture of the hot melt adhesive, it is preferable to use SBS and / or SIS.

[0029] In the present invention, it is more preferable that the styrenic block copolymer (A) contains (i) two types of SBS having different styrene skeleton contents, (ii) three types of SBS having different styrene skeleton contents, (iii) SBS and SIS, or (iv) SBS and two types of SIS having different styrene skeleton contents.

[0030] In the present invention, it is even more preferable that the styrenic block copolymer (A) contains (i) two types of SBS having different styrene skeleton contents or (ii) three types of SBS having different styrene skeleton contents.

[0031] In the present invention, the styrenic block copolymer (A) particularly preferably contains (i) two types of SBSs each having a styrene skeleton content within the range of 25 to 35% by mass, or (ii) three types of SBSs each having a styrene skeleton content within the range of 30 to 45% by mass.

[0032] The styrene skeleton content in the styrenic block copolymer (A) is preferably 10 to 60% by mass, more preferably 15 to 50% by mass, and even more preferably 20 to 45% by mass in 100% by mass of the styrenic block copolymer (A).

[0033] In the present specification, the styrene skeleton content in the styrenic block copolymer (A) refers to the content ratio (% by mass) of the styrene block in the styrenic block copolymer (A). Examples of the method for calculating the styrene skeleton content in the styrenic block copolymer (A) include a method using a proton nuclear magnetic resonance method (1H-NMR method) and an infrared spectroscopy method (IR method) using a cast film in accordance with JIS K 6239-1:2017.

[0034] As the styrenic block copolymer (A), known commercially available products can be widely used. Examples of commercially available products include the product name "Asapren T-438" (styrene skeleton content: 35% by mass) manufactured by Asahi Kasei Corporation, the product name "Asapren T-436" (styrene skeleton content: 30% by mass) manufactured by Asahi Kasei Corporation, the product name "Asapren T-432" (styrene skeleton content: 30% by mass) manufactured by Asahi Kasei Corporation, the product name "D-1161" (styrene skeleton content = 15% by mass) manufactured by Kraton Corporation, the product name "G-1726" (styrene skeleton content = 30 to 32% by mass) manufactured by Kraton Corporation, the product name "G-1645" (styrene skeleton content = 11.5 to 13.5% by mass) manufactured by Kraton Corporation, and the like.

[0035] The content of the styrenic block copolymer (A) in 100% by mass of the hot melt adhesive of the present invention is preferably 10 to 40% by mass, more preferably 12 to 35% by mass, still more preferably 15 to 30% by mass, and particularly preferably 17 to 25% by mass from the viewpoints of adhesive strength and texture.

[0036] The styrene skeleton content in 100% by mass of the hot melt adhesive of the present invention is preferably 0.1 to 30% by mass, more preferably 0.5 to 25% by mass, still more preferably 1 to 20% by mass, and particularly preferably 3 to 15% by mass.

[0037] (Liquid plasticizer (B)) The hot melt adhesive of the present invention contains a liquid plasticizer (B). In this specification, "liquid" means having fluidity at 25°C (i.e., changing its shape according to the container when placed in a container).

[0038] Examples of the liquid plasticizer (B) include polybutene, paraffinic process oil, naphthenic process oil, aromatic process oil, liquid paraffin, hydrocarbon-based synthetic oil, etc. Among these, at least one of polybutene and process oil is preferable. Further, as the process oil, at least one of paraffinic process oil and naphthenic process oil is more preferable. In the present invention, the liquid plasticizer (B) is more preferably paraffinic process oil and / or naphthenic process oil.

[0039] The above-mentioned liquid plasticizers (B) can be used alone or in combination of two or more.

[0040] Examples of polybutene include homopolymers of isobutene, copolymers of isobutene and n-butene, etc.

[0041] As the polybutene, known commercially available products can be widely used. Examples of the commercially available products include "10N" manufactured by NOF Corporation, "Indopol H-100" manufactured by Ineos, "Nisseki Polybutene" manufactured by Shin Nippon Petrochemical Co., Ltd., "Tetrax" manufactured by Shin Nippon Petrochemical Co., Ltd., and the like.

[0042] As the paraffinic process oil, known commercially available products can be widely used. Examples of the commercially available products include "PW-32" manufactured by Idemitsu Kosan Co., Ltd., "Diana Freshia S32" manufactured by Idemitsu Kosan Co., Ltd., "PS-32" manufactured by Idemitsu Kosan Co., Ltd., and the like.

[0043] As the naphthenic process oil, known commercially available products can be widely used. Examples of the commercially available products include "KN-4010" manufactured by PetroChina, "Diana Freshia N28" manufactured by Idemitsu Kosan Co., Ltd., "Diana Freshia N90" manufactured by Idemitsu Kosan Co., Ltd., "Diana Freshia U46" manufactured by Idemitsu Kosan Co., Ltd., "Diana Process Oil NR" manufactured by Idemitsu Kosan Co., Ltd., and the like.

[0044] As the aromatic process oil, known commercially available products can be widely used. Examples of the commercially available products include "Aromax" manufactured by Shin Nippon Oil Corporation.

[0045] The number average molecular weight (Mn) of these process oils is preferably from 200 to 700, more preferably from 300 to 600. The number average molecular weight (Mn) in this specification can be measured, for example, under the following measuring apparatus and measuring conditions. Measuring apparatus: "ACQUITY APC" manufactured by Waters Measuring conditions: Column ·ACQUITY APCXT45 1.7 μm × 1 piece ·ACQUITY APCXT125 2.5 μm × 1 piece ·ACQUITY APCXT450 2.5 μm × 1 piece Mobile phase: Tetrahydrofuran 0.8 mL / min Sample concentration: 0.2 mass% Detector: Differential refractive index (RI) detector Standard substance: Polystyrene (manufactured by Waters, molecular weight: 370 - 2,520,000) Column temperature: 40°C RI detector temperature: 40°C

[0046] As the liquid paraffin, known commercially available products can be widely used. Examples of commercially available products include "P - 100" manufactured by MORESCO and "Kaydol" manufactured by Sonneborn.

[0047] As the hydrocarbon - based synthetic oil, known commercially available products can be widely used. Examples of commercially available products include "Lucant HC - 10" manufactured by Mitsui Chemicals and "Lucant HC - 20" manufactured by Mitsui Chemicals.

[0048] In the present invention, when the content of the liquid plasticizer (B) is 1% by mass or more, the hot - melt adhesive becomes soft and the texture is improved. Also, when the content of the liquid plasticizer (B) is 40% by mass or less, the cohesive force of the hot - melt adhesive is improved and adhesiveness is exhibited.

[0049] In the present invention, the content of the liquid plasticizer (B) is preferably 30 - 90 parts by mass, more preferably 32 - 80 parts by mass, still more preferably 34 - 75 parts by mass, and particularly preferably 36 - 70 parts by mass with respect to 100 parts by mass of the styrene - based block copolymer (A).

[0050] (Adhesion - imparting resin (C)) The hot - melt adhesive of the present invention preferably further contains an adhesion - imparting resin (C). Examples of the adhesion - imparting resin (C) include rosin - based compounds, terpene - based compounds, petroleum resins, etc. These adhesion - imparting resins (C) can be used alone or in combination of two or more. Among these adhesion - imparting resins (C), terpene - based compounds and petroleum resins are preferred, and particularly petroleum resins (especially hydrogenated petroleum resins) are preferred.

[0051] Examples of the rosin-based compound include natural rosin, modified rosin, glycerol ester of natural rosin, glycerol ester of modified rosin, pentaerythritol ester of natural rosin, pentaerythritol ester of modified rosin, and the like.

[0052] Examples of the terpene-based compound include copolymer of natural terpene, three-dimensional polymer of natural terpene, hydrogenated derivative of copolymer of natural terpene, terpene resin, hydrogenated derivative of phenol-modified terpene resin, and the like.

[0053] Examples of the petroleum resin include petroleum resins such as C5-based petroleum resin, C9-based petroleum resin, C5C9-based petroleum resin, dicyclopentadiene-based petroleum resin, and partially hydrogenated petroleum resin and fully hydrogenated petroleum resin obtained by adding hydrogen to these petroleum resins. The C5-based petroleum resin is a petroleum resin made from the C5 fraction of petroleum, the C9-based petroleum resin is a petroleum resin made from the C9 fraction of petroleum, and the C5C9-based petroleum resin is a petroleum resin made from the C5 fraction and the C9 fraction of petroleum. Examples of the C5 fraction include cyclopentadiene, isoprene, pentane, and the like. Examples of the C9 fraction include styrene, vinyltoluene, indene, and the like. As the C9-based petroleum resin and the C5C9-based petroleum resin, those containing styrene, which is a kind of the C9 fraction, in the skeleton are preferable.

[0054] As the tackifier resin (C), a petroleum resin is preferable, and a partially hydrogenated petroleum resin and a fully hydrogenated petroleum resin are more preferable in terms of excellent odor and heat stability of the hot melt adhesive.

[0055] The above-described tackifier resins (C) can be used alone or in combination of two or more.

[0056] The softening point temperature of the tackifier resin (C) is preferably 90°C or higher, more preferably 100°C or higher. The upper limit of the softening point temperature is preferably 140°C. When the softening point of the tackifier resin (C) is 90°C or higher, the hot melt adhesive of the present invention is likely to exhibit good adhesiveness.

[0057] In this specification, the softening point temperature of the tackifier resin is a value measured in accordance with JIS K2207.

[0058] In the present invention, when the content of the tackifier resin (C) is 40% by mass or more, the tackiness of the hot melt adhesive is improved and the adhesion to the adherend is improved. Further, when the content of the tackifier resin (C) is 70% by mass or less, the hot melt adhesive becomes soft and easily exhibits adhesive strength.

[0059] In the present invention, the content of the tackifier resin (C) is preferably 200 to 400 parts by mass, more preferably 250 to 350 parts by mass, and even more preferably 275 to 330 parts by mass with respect to 100 parts by mass of the styrene block copolymer (A).

[0060] As the tackifier resin (C), known commercially available products can be widely used. Examples of commercially available products include the product name "HB-103" manufactured by JXTG Energy, the product name "HA-085" manufactured by JXTG Energy, the product name "HA-103" of JXTG Energy, the product name "HB-125" manufactured by JXTG Energy, the product name "Regalite C-6100L" manufactured by Eastman Chemical, the product name "YS Resin TO-105" manufactured by Yasuhara Chemical, the product name "Alcon P-90" manufactured by Arakawa Chemical, the product name "Alcon P-100" manufactured by Arakawa Chemical, the product name "Alcon M-100" manufactured by Arakawa Chemical, the product name "Imerv P100" manufactured by Idemitsu Kosan, the product name "Scoretts SU400" manufactured by Kolon, the product name "Imerv P100" manufactured by Idemitsu Kosan, and the like.

[0061] (Solid plasticizer (D)) The hot melt adhesive of the present invention preferably further contains a solid plasticizer (D).

[0062] In the present invention, it is preferable that the solid plasticizer (D) contains at least one selected from the group consisting of paraffin wax, polyethylene wax, polypropylene wax, and Fischer-Tropsch wax.

[0063] In the present invention, it is preferable that the solid plasticizer (D) contains a solid plasticizer (D1) and a solid plasticizer (D2). The solid plasticizer (D1) preferably has a melting point in the range of 57 to 80°C, more preferably in the range of 60 to 75°C, and even more preferably in the range of 63 to 70°C. The solid plasticizer (D2) preferably has a melting point in the range of 95 to 141°C, more preferably in the range of 100 to 120°C, and even more preferably in the range of 101 to 110°C.

[0064] In the present invention, it is preferable that the solid plasticizer (D) contains a solid plasticizer (D1) having a melting point in the range of 57 to 80°C and a solid plasticizer (D2) having a melting point in the range of 95 to 141°C.

[0065] In the present invention, it is more preferable that the solid plasticizer (D) contains a solid plasticizer (D1) having a melting point in the range of 60 to 75°C and a solid plasticizer (D2) having a melting point in the range of 100 to 120°C.

[0066] In the present invention, it is even more preferable that the solid plasticizer (D) contains a solid plasticizer (D1) having a melting point in the range of 63 to 70°C and a solid plasticizer (D2) having a melting point in the range of 101 to 110°C.

[0067] In the present invention, the mass ratio (D1 / D2) of the solid plasticizer (D1) to the solid plasticizer (D2) is preferably 1.5 or more, more preferably 1.8 or more, and even more preferably 2.0 or more. In the present invention, the mass ratio (D1 / D2) of the solid plasticizer (D1) to the solid plasticizer (D2) is preferably 20 or less, more preferably 17 or less, and even more preferably 15 or less.

[0068] In the present invention, the content of the solid plasticizer (D1) is preferably 30 to 150 parts by mass with respect to 100 parts by mass of the styrene block copolymer (A), and the content of the solid plasticizer (D2) is preferably 5 to 40 parts by mass with respect to 100 parts by mass of the styrene block copolymer (A). When the contents of the solid plasticizer (D1) and the solid plasticizer (D2) are within the above ranges, the adhesiveness of the hot melt adhesive of the present invention is more excellent, the texture is better, and the tackiness is more suppressed.

[0069] In the present invention, the content of the solid plasticizer (D1) is more preferably 40 to 130 parts by mass with respect to 100 parts by mass of the styrene block copolymer (A), and the content of the solid plasticizer (D2) is more preferably 9 to 30 parts by mass with respect to 100 parts by mass of the styrene block copolymer (A). When the contents of the solid plasticizer (D1) and the solid plasticizer (D2) are within the above ranges, the adhesiveness of the hot melt adhesive of the present invention is even more excellent, the texture is even better, and the tackiness is even more suppressed.

[0070] In the present invention, the content of the solid plasticizer (D1) is even more preferably 50 to 100 parts by mass with respect to 100 parts by mass of the styrene block copolymer (A), and the content of the solid plasticizer (D2) is even more preferably 10 to 23 parts by mass with respect to 100 parts by mass of the styrene block copolymer (A). When the contents of the solid plasticizer (D1) and the solid plasticizer (D2) are within the above ranges, the adhesiveness of the hot melt adhesive of the present invention is particularly excellent, the texture is particularly good, and the tackiness is particularly suppressed.

[0071] In the present invention, the content of the solid plasticizer (D1) is particularly preferably 60 to 90 parts by mass with respect to 100 parts by mass of the styrene block copolymer (A), and the content of the solid plasticizer (D2) is particularly preferably 11 to 18 parts by mass with respect to 100 parts by mass of the styrene block copolymer (A). When the contents of the solid plasticizer (D1) and the solid plasticizer (D2) are within the above ranges, the adhesiveness of the hot melt adhesive of the present invention is the most excellent, the texture is the best, and the tackiness is the most suppressed.

[0072] In the present invention, as the solid plasticizer (D1) having a melting point in the range of 57 to 80°C, known commercially available products can be widely used. Examples of commercially available products include "Paraffin Wax-135" (melting point = 59°C) manufactured by Nippon Seiro Co., Ltd., "Paraffin Wax-145" (melting point = 63°C) manufactured by Nippon Seiro Co., Ltd., "Paraffin Wax-150" (melting point = 66°C) manufactured by Nippon Seiro Co., Ltd., "Paraffin Wax-155" (melting point = 69°C) manufactured by Nippon Seiro Co., Ltd., "Sazol C80" (melting point = 80°C) manufactured by Sazol Wax Co., etc.

[0073] In the present invention, as the solid plasticizer (D2) having a melting point in the range of 100 to 141°C, known commercially available products can be widely used. Examples of commercially available products include "GTL SARAWAX SX-105" (melting point = 102°C) manufactured by Shell M.D.S. (Malaysia) Sdn. Bhd., "FT-115" (melting point = 113°C) manufactured by Nippon Seiro Co., Ltd., "Marcus 200" (melting point = 114°C) manufactured by Marcus Oil and Chemical Co., "EPOLEN N-21" (melting point = 120°C) manufactured by Westlake Chemical Co., "Licocene PP 6102" (melting point = 141°C) manufactured by Clariant Corp., "Sazol Wax H1" (melting point = 112°C) manufactured by Sazol Co., "Sazol Wax H5" (melting point = 117°C) manufactured by Sazol Co., etc.

[0074] (Antioxidant (E)) The hot melt adhesive of the present invention may contain an antioxidant (E). The antioxidant is used to prevent the oxidative degradation of the hot melt adhesive.

[0075] Examples of the antioxidant (E) include hindered phenolic antioxidants 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)]acrylate, and tetrakis[methylene-3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate]methane; sulfur antioxidants such as dilauryl thiodipropionate, lauryl stearyl thiodipropionate, and pentaerythritol tetrakis(3-laurylthiopropionate); and phosphorus antioxidants such as tris(nonylphenyl) phosphite and tris(2,4-di-t-butylphenyl) phosphite. These antioxidants (E) can be used alone or in combination of two or more thereof.

[0076] The content of the antioxidant (E) is preferably 0.1 to 10 parts by mass, more preferably 0.25 to 8 parts by mass, still more preferably 0.5 to 6 parts by mass, and particularly preferably 1 to 5 parts by mass with respect to 100 parts by mass of the styrenic block copolymer (A). When the content of the antioxidant (E) is within the range of 0.1 to 10 parts by mass with respect to 100 parts by mass of the styrenic block copolymer (A), the thermal stability of the hot melt adhesive of the present invention during melting becomes good.

[0077] In the present invention, as the antioxidant (E), known commercially available products can be widely used. Examples of the commercially available products include the product name "IRGANOX1010" manufactured by BASF.

[0078] (Optional additive) The hot melt adhesive of the present invention may contain various additives as necessary. Examples of the various additives include ultraviolet absorbers, particulate fillers, and the like. The ultraviolet absorber is used to improve the light resistance of the hot melt adhesive. The content of the additive can be appropriately adjusted within a range that satisfies the content in the hot melt adhesive of the above-described components (A), (B), (C), (D), and (E).

[0079] Examples of the ultraviolet absorber include benzotriazole-based ultraviolet absorbers 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; benzophenone-based ultraviolet absorbers such as 2-hydroxy-4-methoxybenzophenone; salicylic acid ester-based ultraviolet absorbers; cyanoacrylate-based ultraviolet absorbers; and hindered amine-based light stabilizers. These ultraviolet absorbers can be used alone or in combination of two or more.

[0080] The hot melt adhesive of the present invention can be manufactured by widely adopting a known method using the above-described components. For example, it can be manufactured by charging the above-described components in respective blending amounts into a stirring and kneading machine equipped with a heating device and then heating, stirring, and kneading at 150°C for 1 hour.

[0081] Hereinafter, the physical property values of the hot melt adhesive of the present invention will be described.

[0082] The hot melt adhesive of the present invention has at least one endothermic peak in the range of 45 to 80°C and at least one endothermic peak in the range of 95 to 130°C in the DSC curve obtained when the temperature is raised at a rate of 10°C / min by differential scanning calorimetry (DSC).

[0083] The hot melt adhesive of the present invention preferably has at least one endothermic peak in the range of 48 to 60 °C and at least one endothermic peak in the range of 98 to 115 °C in the DSC curve obtained when the temperature is raised at a rate of 10 °C / min by DSC.

[0084] The hot melt adhesive of the present invention more preferably has at least one endothermic peak in the range of 52 to 55 °C and at least one endothermic peak in the range of 100 to 105 °C in the DSC curve obtained when the temperature is raised at a rate of 10 °C / min by DSC.

[0085] In this specification, in the DSC curve obtained when the temperature is raised at a rate of 10 °C / min by DSC, the area B surrounded by the interpolation baseline A and C in FIG. 1 and the endothermic peak of the DSC curve divided by the sample amount is defined as the heat of fusion ΔH (unit: J / g).

[0086] In the present invention, in the DSC curve obtained when the temperature is raised at a rate of 10 °C / min by DSC, the above-mentioned heat of fusion ΔH for the endothermic peak in the range of 45 to 80 °C is -51.0 to -7.0 J / g, and the above-mentioned heat of fusion ΔH for the endothermic peak in the range of 95 to 130 °C is preferably -4.5 to -0.1 J / g.

[0087] In the present invention, in the DSC curve obtained when the temperature is raised at a rate of 10 °C / min by DSC, the above-mentioned heat of fusion ΔH for the endothermic peak in the range of 45 to 80 °C is -35.0 to -12.0 J / g, and the above-mentioned heat of fusion ΔH for the endothermic peak in the range of 95 to 130 °C is more preferably -3.5 to -0.5 J / g.

[0088] In the present invention, in the DSC curve obtained when the temperature is raised at a rate of 10 °C / min by DSC, the above-mentioned heat of fusion ΔH for the endothermic peak in the range of 45 to 80 °C is -25.0 to -15.0 J / g, and the above-mentioned heat of fusion ΔH for the endothermic peak in the range of 95 to 130 °C is even more preferably -3.0 to -1.0 J / g.

[0089] The melt viscosity of the hot melt adhesive of the present invention at 160°C is preferably 950 to 5000 mPa·s. In this specification, the "melt viscosity" means the viscosity of the hot melt adhesive in a heat-melted state at a certain temperature. If the melt viscosity of the hot melt adhesive at 160°C is 950 mPa·s or more, adhesiveness is exhibited. On the other hand, considering the handleability as a hot melt adhesive, the melt viscosity of the hot melt adhesive at 160°C is preferably 5000 mPa·s or less.

[0090] In this specification, the melt viscosity of the hot melt adhesive at 160°C is defined as a value obtained based on JIS K 6862 (Brookfield single-cylinder rotational viscometer for melt viscosity test method of hot melt adhesives, spindle 4-21).

[0091] 2. Laminate The present invention is a laminate in which a pair of base materials are joined by the above hot melt adhesive. The laminate is preferably a laminate for sanitary materials.

[0092] Examples of the base material include non-woven fabric, porous base material (e.g., tissue, etc.), polyolefin resin film, and the like.

[0093] Examples of the non-woven fabric include spunbond non-woven fabric, meltblown non-woven fabric, spunlace non-woven fabric, air-through non-woven fabric, and the like.

[0094] As a method for joining a pair of base materials 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. The heating temperature is preferably 140 °C or higher, more preferably 150 °C or higher. Also, the heating temperature is preferably 180 °C or lower, more preferably 170 °C or lower. Next, the molten hot melt adhesive is applied to one of the base materials. Next, after laminating the other base material on the applied hot melt adhesive, the hot melt adhesive is cooled and solidified, whereby a pair of base materials can be joined.

[0095] Examples of the method for applying the hot melt adhesive heated and melted include slot coater coating, roll coater coating, spiral coating, summit coating, omega coating, control seam coating, slot spray coating, curtain spray coating, and dot coating.

[0096] 3. Disposable product The present invention is a disposable product using the above laminate. Examples of the disposable product include so-called sanitary materials such as paper diapers, sanitary napkins, pet sheets, hospital gowns, and surgical gowns.

Example

[0097] The present invention will be specifically described below with reference to examples, but the present invention is not limited to the following examples.

[0098] The raw materials used in the examples and comparative examples are as follows.

[0099] <Styrene block copolymer (A)> · (A1) Styrene-butadiene-styrene block copolymer (SBS): manufactured by Asahi Kasei Corporation, product name "Asapren T-436", styrene skeleton content = 35% by mass · (A2) Styrene-butadiene-styrene block copolymer (SBS): manufactured by Asahi Kasei Corporation, product name "Asapren T-432", styrene skeleton content = 30% by mass ·(A3) Styrene-butadiene-styrene block copolymer (SBS): manufactured by Asahi Kasei Corporation, product name "Asapren T-439", styrene skeleton content = 45% by mass ·(A4) Styrene-isoprene-styrene block copolymer (SIS): manufactured by Clayton Polymer, product name "D-1161", sty rene skeleton content = 15% by mass ·(A5) Styrene-isoprene-styrene block copolymer (SIS): manufactured by Sinopec, product name "SIS YH-1209", styrene skeleton content = 29% by mass

[0100] <Liquid plasticizer (B)> ·(B1) Naphthenic process oil: manufactured by PetroChina, product name "KN-4010", pour point = -15.0 °C, number average molecular weight (Mn) = 455 ·(B2) Paraffinic process oil: manufactured by Idemitsu Kosan Co., Ltd., product name "PS-32", pour point = -17.5 °C, number average molecular weight (Mn) = 447

[0101] <Tackifying resin (C)> ·(C1) Hydrogenated petroleum resin: manufactured by TonenGeneral Sekiyu K.K., product name "HB-103", softening point = 103 °C ·(C2) Hydrogenated petroleum resin: manufactured by Eastman Chemical Company, product name "Regalite C-6100L", softening point = 100 °C ·(C3) Aromatic modified terpene resin: manufactured by Yasuhara Chemical Co., Ltd., product name "YS Resin TO-105", softening point = 105 °C

[0102] <Solid plasticizer (D)> ·(D1-1) Paraffin wax: manufactured by Nippon Seiro Co., Ltd., product name "Paraffin Wax-135", melting point = 59 °C ·(D1-2) Paraffin wax: manufactured by Nippon Seiro Co., Ltd., product name "Paraffin Wax-150", melting point = 66 °C ·(D1-3) Fischer-Tropsch wax: manufactured by Sasol Wax, product name "Sasol C80", melting point = 80 °C ·(D1-4) Fischer-Tropsch wax: manufactured by Nippon Seiro Co., Ltd., product name "Paraffin Wax-115", melting point = 48°C ·(D2-1) Fischer-Tropsch wax: manufactured by Shell M.D.S. (Malaysia) Sdn. Bhd., product name "GTL SARAWAX SX-105", melting point = 102°C ·(D2-2) Polyethylene wax: manufactured by Westlake Chemical Corporation, product name "EPOLEN N-21", melting point = 120°C ·(D2-3) Polyethylene wax: manufactured by Marcus Oil and Chemical Co., product name "Marcus 200", melting point = 114°C ·(D2-4) Polypropylene wax: manufactured by Clariant, product name "Licocene PP 6102", melting point = 141°C

[0103] <Antioxidant (E)> ·(E-1) Phenolic antioxidant: manufactured by BASF, product name "IRGANOX1010"

[0104] (Examples and Comparative Examples) The above-mentioned raw materials were each put into a stirring and kneading machine equipped with a heating device in the blending amounts shown in Tables 1-1 and 1-2, and then kneaded while heating at 150°C for 1 hour, and cooled until it became solid to produce a hot melt adhesive. Note that the numerical values of each raw material in Tables 1-1 and 1-2 are all in parts by mass.

[0105] For the manufactured hot melt adhesives, the physical property values were evaluated by the following measurement methods. These results are shown in Tables 1-1 and 1-2.

[0106] (Endothermic Peak Measurement Method Using a DSC Measuring Device) As a measurement sample, 3 mg of a hot melt adhesive was sealed in an aluminum pan, and measurement was performed using a differential scanning calorimeter (manufactured by Shimadzu Corporation, product name "DSC-60", atmosphere control device: FC-60A, workstation: TA-60WS). First, under a nitrogen atmosphere (flow rate: 300 mL / min), the first temperature increase of the measurement sample was performed from 23 °C to 120 °C at a rate of 10 °C / min, and it was held at 120 °C for 5 minutes. Then, the measurement sample was cooled from 120 °C to 0 °C at a rate of 10 °C / min and held at 0 °C for 5 minutes. Next, under a nitrogen atmosphere (flow rate: 300 mL / min), the second temperature increase of the measurement sample was performed from 0 °C to 150 °C at a rate of 10 °C / min, and it was held at 150 °C for 5 minutes. Based on the DSC curve obtained during the second temperature increase, the peak temperature (°C), peak height (mW / mg), and heat of fusion ΔH (J / g) based on the peak area in the low temperature region (less than 90 °C) and the high temperature region (90 °C or higher) of the endothermic curve were determined.

[0107] (Adhesion evaluation by measuring adhesion strength) The hot melt adhesive was applied to the first nonwoven fabric (spunbond nonwoven fabric: 16 g / m 2 ) by slot coating at a coating temperature of 150 °C. The coating amount was 5 g / m 2 , and the coating width was 25 mm. Next, a second nonwoven fabric (spunbond nonwoven fabric: 16 g / m 2 ) was separately prepared, laminated on the first nonwoven fabric coated with the hot melt adhesive prepared as described above, and pressure-bonded at 23 °C to prepare a laminate. At this time, the time from when the hot melt adhesive was applied to the first nonwoven fabric until the second nonwoven fabric was pressure-bonded and laminated was 1 second. The laminate was stored for 24 hours under the conditions of 23 °C and an atmosphere of 50% relative humidity to cool the hot melt adhesive. Next, the cooled laminate was cut into strips 100 mm wide in the longitudinal direction (the coating direction of the hot melt adhesive) and 25 mm in the direction perpendicular to the longitudinal direction to prepare test pieces.

[0108] Using the test pieces prepared as described above, a T-peel test was conducted at a peel rate of 100 mm / min with a tensile testing machine (manufactured by Shimadzu Corporation, product name "Autograph AGS-X") in a direction perpendicular to the longitudinal direction (the coating direction of the hot melt adhesive) under an atmosphere of 23°C, and the adhesive strength (N) of the hot melt adhesive was measured. If the numerical value of the adhesive strength (N) is 0.10 or more, it is evaluated that there is no problem for actual use.

[0109] (Texture evaluation by Shore A hardness measurement) A hot melt adhesive was poured into a circular plastic container with a diameter of 50 mm to a height of 15 mm from the bottom of the container, and the container was stored at 23°C for 24 hours to cool the hot melt adhesive. Then, a hardness meter (manufactured by Asker Co., Ltd., Asker rubber hardness meter type A) was pressed vertically against the surface of the hot melt adhesive from above the circular plastic container for 10 seconds under an atmosphere of 23°C, and the Shore A hardness was read. If the numerical value of the Shore A hardness is 40 or less, it is evaluated that there is no problem in actual use.

[0110] (Tackiness evaluation by peel strength measurement) The hot melt adhesive was applied by slot coating at a coating temperature of 150°C to a non-woven fabric (spunbond non-woven fabric: 16 g / m 2 ). The coating amount was 5 g / m 2 , and the coating width was 25 mm. Then, a tissue (basis weight 30 g / m 2 ) was separately prepared and laminated on the non-woven fabric coated with the hot melt adhesive, and the laminate was prepared by crimping at 23°C. The prepared laminate was sandwiched between acrylic plates of 50 mm × 60 mm, and a load of 67 g / cm 2 was applied on the surface of the acrylic plate, and it was left for 2 hours under the conditions of 40°C and a relative humidity of 50%. Then, the load and the acrylic plates were removed, and using a tensile testing machine (manufactured by Shimadzu Corporation, product name "Autograph AGS-X"), the peel strength (N) required to peel the non-woven fabric from the tissue was measured at a peel rate of 100 mm / min under an atmosphere of 23°C. If the numerical value of the peel strength (N) is 0.30 or less, it is evaluated that there is no problem in actual use. From the viewpoint of suppressing the tackiness, the numerical value of the peel strength (N) is preferably 0.27 or less. From the viewpoint of further suppressing the tackiness, the numerical value of the peel strength (N) is more preferably 0.20 or less. From the viewpoint of further suppressing the tackiness even more, the numerical value of the peel strength (N) is even more preferably 0.15 or less. On the other hand, if the numerical value of the peel strength (N) exceeds 0.30, there is a problem that the tackiness cannot be suppressed.

[0111] The results are shown in Table 1-1 and Table 1-2. In Comparative Examples 1 and 2 of Table 1-2, "-" in the item of physical property values means that the measurement is impossible.

[0112]

Table 1-1

[0113]

Table 1-2

Claims

1. It contains a styrenic block copolymer (A), a liquid plasticizer (B), a tackifier resin (C), and a solid plasticizer (D), In the DSC curve obtained when the temperature is raised at a rate of 10 °C / min by differential scanning calorimetry (DSC), it has at least one endothermic peak in the range of 45 to 80 °C and at least one endothermic peak in the range of 95 to 130 °C, The solid plasticizer (D) contains a solid plasticizer (D1) having a melting point in the range of 57 to 80 °C and a solid plasticizer (D2) having a melting point in the range of 95 to 141 °C, The content of the liquid plasticizer (B) is 30 to 90 parts by mass with respect to 100 parts by mass of the styrenic block copolymer (A), The content of the tackifier resin (C) is 200 to 400 parts by mass with respect to 100 parts by mass of the styrenic block copolymer (A), The content of the solid plasticizer (D1) is 30 to 150 parts by mass with respect to 100 parts by mass of the styrenic block copolymer (A), The content of the solid plasticizer (D2) is 5 to 40 parts by mass with respect to 100 parts by mass of the styrenic block copolymer (A), and it is a hot melt adhesive characterized by this.

2. The hot melt adhesive according to Claim 1, wherein the styrenic block copolymer (A) contains at least one of a styrene-butadiene-styrene block copolymer (SBS) and a styrene-isoprene-styrene block copolymer (SIS).

3. The solid plasticizer (D1) contains at least one selected from the group consisting of paraffin wax and Fischer-Tropsch wax, The hot melt adhesive according to Claim 1 or 2, wherein the solid plasticizer (D2) contains at least one selected from the group consisting of polyethylene wax, polypropylene wax, and Fischer-Tropsch wax.

4. A laminate in which a pair of base materials are joined by the hot melt adhesive according to any one of Claims 1 to 3.

5. A disposable product using the laminate according to Claim 4.

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