Hot melt composition

Abstract

The present invention aims to provide a hot melt composition that is excellent in workability, heat flow resistance, adhesion, disintegration balance, volatile resistance, and heat creep resistance. The present invention is a hot melt composition containing: as a thermoplastic elastomer (1), a styrene-based thermoplastic elastomer (1a) having a weight average molecular weight of 300,000 or more, a styrene-based thermoplastic elastomer (1b) having a styrene content of 20% by mass or less, and an olefin-based thermoplastic elastomer (1c) containing an ethylene-propylene rubber and / or a butyl rubber; as a tackifier (2), an aromatic petroleum resin (2a), a terpene phenol resin (2b), and an amorphous poly-alpha-olefin (2c); a high molecular weight paraffin oil (3a) having a weight average molecular weight of 1,000 or more; and a low molecular weight paraffin oil (3b) having a weight average molecular weight of less than 1,000.

Description

Technical Field

[0001] This invention relates to hot melt compositions. Background Technology

[0002] To date, hot melt composites have been used to bond lenses to housings in automotive lighting (such as headlights).

[0003] For hot melt compositions used in the bonding of lenses and housings in automotive lighting fixtures, excellent workability is required (specifically, for example, the viscosity of the hot melt composition when applied to the substrate is within an appropriate range; the same applies below); excellent heat resistance and flowability (specifically, for example, the hot melt composition (adhesive layer) after bonding the substrate with the hot melt composition does not easily soften or deform under high temperature conditions; the same applies below); excellent balance between adhesion and disintegration; excellent volatility resistance (therefore, the interior of the automotive lighting fixture (automotive lamp) is not easily blurred); and excellent heat creep resistance (adhesion retention under heating and applied load conditions), etc.

[0004] Adhesion refers to the tightness of the bond between the first component and the second component after using a hot melt composition.

[0005] Separability (disintegration) means that when the first component and the second component are bonded together using a hot melt composition, the cured product of the hot melt composition is easily peeled off from the interface between the first component and the second component, and the adhesive layer is not easily broken when the cured product is separated from the substrate (adhesive).

[0006] Patent documents 1 and 2, for example, have proposed hot melt compositions that can be used in the bonding of lenses and housings in automotive lighting.

[0007] Patent document 1 describes a hot melt composition containing: a styrene-based thermoplastic elastomer with a weight average molecular weight of 300,000 or more, a tackifier, paraffin oil 1 with a weight average molecular weight of 1,000 or more, and paraffin oil 2 with a weight average molecular weight of less than 1,000.

[0008] Patent Document 2 describes a readily disintegratable hot-melt composition, characterized in that it comprises, relative to 100 parts by weight, 300 to 1000 parts by weight of a SEEPS block copolymer (A) with a weight-average molecular weight of 150,000 or more, a kinematic viscosity (40°C) of 200 to 1000 mm. 2 The product consists of paraffin oil (B) at a weight ratio of / s, 50 to 400 parts by weight of an aromatic petroleum resin with a softening point of 100°C or higher (C), and 50 to 600 parts by weight of a terpene resin (D), without polypropylene wax. Furthermore, Patent Document 2 describes a tendency for poor disintegration when using terpene phenol resin as a thickener.

[0009] Existing technical documents

[0010] Patent documents

[0011] Patent Document 1: Japanese Patent Application Publication No. 2018-104594

[0012] Patent Document 2: Japanese Patent No. 6634044 Summary of the Invention

[0013] The problem that the invention aims to solve

[0014] In this invention, the inventors prepared a hot melt composition with reference to Patent Documents 1 and 2 and evaluated it. The results showed that such a composition sometimes had poor workability, heat-resistant flowability, balance between sealing and disintegration, volatility resistance, and heat creep resistance.

[0015] Therefore, the object of the present invention is to provide a hot melt composition with excellent workability, heat resistance, flowability, sealing and disintegration properties, volatility resistance and heat creep resistance.

[0016] Methods for solving problems

[0017] In order to solve the above-mentioned problems, the inventors conducted in-depth research and found that the following hot-melt composition can achieve the desired effect. It contains a styrene-based thermoplastic elastomer (1) with a weight average molecular weight of more than 300,000, a styrene-based thermoplastic elastomer (1b) with a styrene content of less than 20% by mass, and an olefin-based thermoplastic elastomer (1c) containing ethylene propylene rubber and / or butyl rubber as a thermoplastic elastomer (1), an aromatic petroleum resin (2a), a terpene phenol resin (2b), and an amorphous polyα-olefin (2c) as a tackifying material (2), and a high molecular weight paraffin oil (3a) with a weight average molecular weight of more than 1,000 and a low molecular weight paraffin oil (3b) with a weight average molecular weight of less than 1,000 as a paraffin oil. This invention was thus completed.

[0018] Based on the above understanding, the present invention specifically solves the above-mentioned problems by adopting the following configuration.

[0019] [1] A hot melt composition comprising: a styrene-based thermoplastic elastomer (1a) with a weight average molecular weight of 300,000 or more, a styrene-based thermoplastic elastomer (1b) with a styrene content of 20% by mass or less, and an olefin-based thermoplastic elastomer (1c) comprising ethylene propylene rubber and / or butyl rubber; an aromatic petroleum resin (2a), a terpene phenolic resin (2b), and an amorphous polyα-olefin (2c) as a tackifying material (2); a high molecular weight paraffin oil (3a) with a weight average molecular weight of 1,000 or more; and a low molecular weight paraffin oil (3b) with a weight average molecular weight of less than 1,000.

[0020] [2] According to the hot melt composition of [1], the content of the styrene-based thermoplastic elastomer (1b) is 10 to 50 parts by mass relative to 100 parts by mass of the styrene-based thermoplastic elastomer (1a).

[0021] [3] According to the hot melt composition of [1] or [2], wherein the content of the olefinic thermoplastic elastomer (1c) is 30 to 70 parts by mass relative to 100 parts by mass of the styrene-based thermoplastic elastomer (1a).

[0022] [4] The hot melt composition according to any one of [1] to [3], wherein the styrene-based thermoplastic elastomer (1a) comprises SEEPS.

[0023] [5] The hot melt composition according to any one of [1] to [4], wherein the total content of the aromatic petroleum resin (2a) and the terpene phenol resin (2b) is 200 to 600 parts by weight relative to 100 parts by weight of the styrene-based thermoplastic elastomer (1a).

[0024] [6] The hot melt composition according to any one of [1] to [5] is used in automotive lamps.

[0025] The effects of the invention

[0026] The hot melt composition of the present invention has excellent workability, heat resistance and flowability, a balance between adhesion and disintegration, volatility resistance and heat creep resistance. Detailed Implementation

[0027] The present invention will now be described in detail.

[0028] It should be noted that in this specification, the numerical range indicated by “~” means the range of values ​​recorded before and after “~” as the lower and upper limits.

[0029] Unless otherwise specified in this specification, each component can be used individually or in combination of two or more substances corresponding to that component. When a component contains two or more substances, the content of the component refers to the total content of the two or more substances.

[0030] In this specification, (meth)acryloyl group means acryloyl group or methacryloyl group.

[0031] In this specification, the superiority of at least one of workability, heat-resistant flowability, balance between adhesion and disintegration, volatility resistance, and heat creep resistance is sometimes referred to as superior performance of the present invention. Superior balance between adhesion and disintegration, for example, means, maintaining the required adhesion force (peel strength) while simultaneously reducing the required peel strength for disintegration.

[0032] [Hot-melt composition]

[0033] The hot melt composition of the present invention (the composition of the present invention) is a hot melt composition containing the following components: a styrene-based thermoplastic elastomer (1a) with a weight average molecular weight of 300,000 or more, a styrene-based thermoplastic elastomer (1b) with a styrene content of 20% by mass or less, and an olefin-based thermoplastic elastomer (1c) comprising ethylene propylene rubber and / or butyl rubber; an aromatic petroleum resin (2a), a terpene phenolic resin (2b), and an amorphous polyα-olefin (2c) as a tackifying material (2); a high molecular weight paraffin oil (3a) with a weight average molecular weight of 1000 or more; and a low molecular weight paraffin oil (3b) with a weight average molecular weight of less than 1000.

[0034] The components contained in the composition of the present invention are described in detail below.

[0035] It should be noted that the styrene-based thermoplastic elastomer (1a) contained in the composition of the present invention with a weight-average molecular weight of 300,000 or more is sometimes referred to as "specific St-based elastomer (1a)" or simply "(1a)".

[0036] In addition, styrene-based thermoplastic elastomers (1b) with a styrene content of less than 20% by mass are sometimes referred to as "specific St-based elastomers (1b)" or simply "(1b)".

[0037] Olefin-based thermoplastic elastomers (1c) are sometimes referred to as “specific olefin-based thermoplastic elastomers (1c)” or simply “(1c)”.

[0038] Sometimes, high molecular weight paraffin oil (3a) with a weight average molecular weight of 1000 or more is referred to as "high molecular weight paraffin oil (3a)" or simply "(3a)".

[0039] Sometimes, low molecular weight paraffin oil (3b) with a weight average molecular weight of less than 1000 is referred to as "low molecular weight paraffin oil (3b)" or simply "(3b)".

[0040] <<Thermoplastic Elastomers (1)>>

[0041] The composition of the present invention contains a styrene-based thermoplastic elastomer (1a) with a weight-average molecular weight of 300,000 or more, a styrene-based thermoplastic elastomer (1b) with a styrene content of 20% by mass or less, and an olefin-based thermoplastic elastomer (1c) as the thermoplastic elastomer (1). Furthermore, the olefin-based thermoplastic elastomer (1c) comprises ethylene propylene rubber and / or butyl rubber.

[0042] In this invention, the term thermoplastic elastomer refers to a polymer that softens when heated and has rubber-like elasticity when cooled.

[0043] Styrene-based thermoplastic elastomers refer to block copolymers, which have: polymer blocks having repeating units formed from styrene or styrene derivatives and polymer blocks containing structural units from conjugated dienes.

[0044] <Styrene-based thermoplastic elastomers (1a)>

[0045] In this invention, the styrene-based thermoplastic elastomer (1a) contained in the thermoplastic elastomer (1) has a weight-average molecular weight of 300,000 or more. The composition of this invention exhibits excellent heat resistance and flowability by containing a specific St-based elastomer (1a).

[0046] Examples of the above-mentioned styrene-based thermoplastic elastomers (1a) include styrene-isoprene-styrene block copolymers (SIS), styrene-butadiene-styrene block copolymers (SBS), styrene-ethylene-propylene-styrene block copolymers (SEPS), styrene-ethylene-butene-styrene block copolymers (SEBS), and styrene-ethylene-ethylene-propylene-styrene block copolymers (SEEPS).

[0047] From the viewpoint of achieving better results in this invention, it is preferred that the styrene-based thermoplastic elastomer (1a) contains SEEPS.

[0048] <Weight-average molecular weight of styrene-based thermoplastic elastomers (1a)>

[0049] In this invention, the weight-average molecular weight of the styrene-based thermoplastic elastomer (1a) is 300,000 or more.

[0050] From the viewpoint that the present invention has superior effects, heat resistance, mechanical properties and disintegration, the weight-average molecular weight (Mw) of the above-mentioned styrene-based thermoplastic elastomer (1a) is preferably 300,000 to 600,000, more preferably 300,000 or more but less than 500,000, and even more preferably 350,000 or more but less than 450,000.

[0051] In this invention, the weight-average molecular weight of the styrene-based thermoplastic elastomer (1a) refers to the weight-average molecular weight converted from standard polystyrene based on the measurement value obtained by gel permeation chromatography (GPC). The measurement conditions for the weight-average molecular weight of the above-mentioned styrene-based thermoplastic elastomer (1a) are as follows.

[0052] (Measurement conditions)

[0053] GPC: LC Solution (manufactured by SHIMAZU)

[0054] Detector: SPD-20A (manufactured by SHIMAZU)

[0055] Column: Connect two ALPHA-5000 (TOSO) rods in series.

[0056] Solvent: Tetrahydrofuran

[0057] Temperature: 40℃

[0058] Flow rate: 0.5 ml / min

[0059] Concentration: 2mg / ml

[0060] Standard sample: polystyrene

[0061] ·Styrene content

[0062] From the viewpoint of achieving better results, heat resistance, and mechanical properties, the styrene content of the above-mentioned styrene-based thermoplastic elastomer (1a) is preferably 25 to 40% by mass, more preferably 25 to 35% by mass.

[0063] The styrene content of styrene-based thermoplastic elastomers refers to the ratio of styrene repeating units in the styrene-based thermoplastic elastomer.

[0064] In this invention, the styrene content of styrene-based thermoplastic elastomers can be determined by thermal decomposition GC-MS (thermal decomposition gas chromatography-mass analysis device) (the same below).

[0065] The styrene content (mass %) of styrene-based thermoplastic elastomers can be set as the proportion of styrene and / or styrene derivatives in the total amount of monomers used in the manufacture of styrene-based thermoplastic elastomers.

[0066] <Styrene-based thermoplastic elastomers (1b)>

[0067] In this invention, the styrene content of the styrene-based thermoplastic elastomer (1b) contained in the thermoplastic elastomer (1) is 20% by mass or less.

[0068] By including a styrene-based thermoplastic elastomer (1b), the composition of the present invention achieves an excellent balance in workability, adhesion and disintegration.

[0069] Examples of the above-mentioned styrene-based thermoplastic elastomers (1b) include styrene-isoprene-styrene block copolymers (SIS), styrene-butadiene-styrene block copolymers (SBS), styrene-ethylene-propylene-styrene block copolymers (SEPS), styrene-ethylene-butene-styrene block copolymers (SEBS), and styrene-ethylene-ethylene-propylene-styrene block copolymers (SEEPS).

[0070] From the viewpoint of achieving better results in this invention, it is preferred that the styrene-based thermoplastic elastomer (1b) contains SEPS and / or SEBS, and more preferably contains SEPS.

[0071] As SEPS, polymers represented by the following formula can be listed, for example.

[0072] [Chemistry 1]

[0073]

[0074] In the above formula, l+m+n can be set as a value corresponding to the weight-average molecular weight of the styrene-based thermoplastic elastomer (1b) described later, and l+n can be set as a value corresponding to the styrene content of the styrene-based thermoplastic elastomer (1b) described later.

[0075] <Styrene content>

[0076] In this invention, the styrene content of the above-mentioned styrene-based thermoplastic elastomer (1b) is 20% by mass or less.

[0077] From the viewpoint of superior performance of the present invention (especially the balance between workability, sealing and disintegration), it is preferable that the styrene content of the above-mentioned styrene-based thermoplastic elastomer (1b) is 10 to 18% by mass, more preferably 10 to 15% by mass.

[0078] The method for determining the styrene content of styrene-based thermoplastic elastomers (1b) is the same as described above.

[0079] (Weight-average molecular weight of styrene-based thermoplastic elastomer (1b))

[0080] From the viewpoint of achieving better results in this invention, it is preferable that the weight-average molecular weight (Mw) of the above-mentioned styrene-based thermoplastic elastomer (1b) is less than 300,000, more preferably 50,000 to 250,000, and even more preferably 100,000 to 200,000.

[0081] The method for determining the weight-average molecular weight of styrene-based thermoplastic elastomer (1b) is the same as the method for determining the weight-average molecular weight of styrene-based thermoplastic elastomer (1a) described above.

[0082] (Content of styrene-based thermoplastic elastomer (1b))

[0083] From the viewpoint of achieving better results of the present invention (especially the balance between workability, and / or, adhesion and disintegration), the content of styrene-based thermoplastic elastomer (1b) relative to 100 parts by weight of styrene-based thermoplastic elastomer (1a) is preferably 10 to 50 parts by weight, more preferably 20 to 40 parts by weight.

[0084] <Olefin-based thermoplastic elastomers (1c)>

[0085] The composition of the present invention contains an olefin-based thermoplastic elastomer (1c) as the thermoplastic elastomer (1), wherein the olefin-based thermoplastic elastomer (1c) comprises ethylene propylene rubber and / or butyl rubber.

[0086] The composition of the present invention, by containing the above-mentioned olefin-based thermoplastic elastomer (1c), exhibits excellent workability and heat creep resistance.

[0087] From the viewpoint of achieving better results in this invention (especially the balance between adhesion and disintegration, and heat creep resistance), it is preferable that the above-mentioned olefin-based thermoplastic elastomer (1c) includes ethylene propylene rubber.

[0088] (Ethylene propylene rubber)

[0089] Ethylene propylene rubber (EPR), as an olefin-based thermoplastic elastomer (1c), is a copolymer rubber consisting only of ethylene and propylene. Furthermore, in this invention, the EPR does not contain ethylene-propylene-diene rubber (EPDM).

[0090] (Butyl rubber)

[0091] Butyl rubber is a copolymer of isobutylene and isoprene. Generally, the main component of the repeating units that make up butyl rubber is the isobutylene repeating unit.

[0092] (Weight-average molecular weight of olefin-based elastomers (1c))

[0093] From the viewpoint of achieving better results with the present invention, the weight-average molecular weight (Mw) of the above-mentioned olefin-based thermoplastic elastomer (1c) is preferably 200,000 to 500,000, more preferably 300,000 to 400,000.

[0094] The method for determining the weight-average molecular weight of olefin-based thermoplastic elastomers (1c) is described below.

[0095] (Measurement conditions)

[0096] GPC: HLC-8321GPC / HT (Tosoh Manufacturing)

[0097] Detector: Differential Refractive Index (RI) Tosoh Manufacturing

[0098] Column: Connect one TSKgel guardcolumn HHR(S) and two TSKgel GMHHR-H(S)HT in series.

[0099] Solvent: o-dichlorobenzene

[0100] Temperature: 145℃

[0101] Flow rate: 1.0 ml / min

[0102] Concentration: 0.1 wt% / vol%

[0103] Standard sample: polystyrene

[0104] (Content of olefin-based thermoplastic elastomer (1c))

[0105] (Content of ethylene propylene rubber or butyl rubber. The content of olefin-based thermoplastic elastomer (1c) is the total content of ethylene propylene rubber and butyl rubber when they are used together.) From the viewpoint of achieving better results of the present invention (especially the balance between adhesion and disintegration, and heat creep resistance), the content of olefin-based thermoplastic elastomer (1c) is preferably 30 to 70 parts by mass, more preferably 40 to 60 parts by mass, relative to 100 parts by mass of styrene-based thermoplastic elastomer (1a).

[0106] <<Tackifying Materials (2)>>

[0107] The composition of the present invention contains an aromatic petroleum resin (2a), a terpene phenol resin (2b), and an amorphous poly-α-olefin (2c) as a tackifying material (2).

[0108] In this invention, the tackifying material (2) can impart adhesiveness to the hot-melt composition.

[0109] It should be noted that the thermoplastic elastomer (1) does not contain tackifying materials (2).

[0110] <Aromatic Petroleum Resins (2a)>

[0111] In this invention, the aromatic petroleum resin (2a) contained as a tackifying material (2) refers to a resin having an aromatic hydrocarbon group.

[0112] Regarding aromatic petroleum resins (2a), polymers can be listed as one of the preferred options.

[0113] As an aromatic petroleum resin (2a), polymers of styrene monomers (e.g., styrene, α-methyl-styrene, 4-methyl-α-methyl-styrene) can be listed as examples.

[0114] As an aromatic petroleum resin (2a), aromatic hydrocarbon resins can be listed.

[0115] (Content of aromatic petroleum resin (2a))

[0116] From the viewpoint of achieving better results with the present invention, the content of aromatic petroleum resin (2a) relative to 100 parts by weight of styrene-based thermoplastic elastomer (1a) is preferably 100 to 500 parts by weight, more preferably 150 to 300 parts by weight, and even more preferably 180 to 220 parts by weight.

[0117] <Terpene Phenolic Resin (2b)>

[0118] The terpene phenol resin (2b) contained in the tackifying material (2) of this invention refers to a polymer containing structural units from terpene compounds and structural units from phenolic compounds.

[0119] The composition of the present invention, by containing terpene phenol resin (2b), achieves an excellent balance of workability, adhesion and disintegration.

[0120] Examples of the terpene compounds that can form terpene phenolic resins (2b) include monoterpenes such as α-pinene, β-pinene, and limonene (including d-form, l-form, and d / l-form (dipentene)).

[0121] Phenolic compounds that can form terpene phenolic resins (2b) include, for example, phenol, m-cresol, o-cresol, p-cresol, bisphenol A, etc.

[0122] Examples of terpene phenol resins (2b) include copolymers of terpenes and phenolic compounds (terpene-phenol copolymer resins), products of phenol-modified homopolymers or copolymers of terpenes (phenol-modified terpene resins), and hydrogenated terpene phenol resins that have been hydrogenated.

[0123] (Content of terpene phenol resin (2b))

[0124] From the viewpoint of achieving better results with the present invention, the content of terpene phenol resin (2b) relative to 100 parts by weight of styrene-based thermoplastic elastomer (1a) is preferably 100 to 300 parts by weight, more preferably 110 to 200 parts by weight, and even more preferably 120 to 180 parts by weight.

[0125] (Total content of aromatic petroleum resin (2a) and terpene phenol resin (2b))

[0126] From the viewpoint of achieving better results with the present invention, the total content of aromatic petroleum resin (2a) and terpene phenol resin (2b) relative to 100 parts by weight of styrene-based thermoplastic elastomer (1a) is preferably 200 to 600 parts by weight, more preferably 200 to 500 parts by weight, and even more preferably 300 to 400 parts by weight.

[0127] <Amorphous polyalphaolefin (2c)>

[0128] Amorphous polyalphaolefins (2c) refer to amorphous (non-morphic) polymers whose main chain backbone is derived from alpha-olefins.

[0129] Examples of amorphous polyα-olefins (2c) include homopolymers of ethylene, propylene, and butene; and copolymers of at least two of ethylene, propylene, and butene.

[0130] Examples of the aforementioned polymers include propylene / ethylene copolymers (polymers of propylene and ethylene), propylene / butene copolymers (polymers of propylene and butene), and ethylene / propylene / butene copolymers (polymers of ethylene, propylene, and butene).

[0131] It should be noted that, as described above, the thermoplastic elastomer (1) does not contain the tackifying material (2), therefore the olefin-based thermoplastic elastomer (1c) that is the thermoplastic elastomer (1) does not contain amorphous polyalphaolefin (2c). In addition, in this specification, amorphous polyalphaolefin is sometimes referred to as APAO.

[0132] (Weight-average molecular weight of amorphous polyalphaolefin (2c))

[0133] From the viewpoint of achieving better results with the present invention, the weight-average molecular weight (Mw) of the above-mentioned amorphous poly-α-olefin (2c) is preferably 30,000 to 150,000, more preferably 40,000 to 100,000.

[0134] The method for determining the weight-average molecular weight of amorphous poly-α-olefin (2c) is the same as the method for determining the weight-average molecular weight of olefin-based thermoplastic elastomers (1c) described above.

[0135] (Content of amorphous polyalphaolefin (2c))

[0136] The content of the amorphous polyα-olefin (2c) is preferably 1 to 20 parts by mass relative to 100 parts by mass of the styrene-based thermoplastic elastomer (1a), more preferably 1 to 10 parts by mass, and even more preferably 1 to 5 parts by mass.

[0137] <High molecular weight paraffin oil (3a)>

[0138] The composition of the present invention contains a high molecular weight paraffin oil (3a) with a weight average molecular weight of 1000 or more as the paraffin oil.

[0139] The composition of the present invention has excellent heat resistance, fluidity and volatility resistance by containing high molecular weight paraffin oil (3a).

[0140] Examples of high molecular weight paraffin oils (3a) include, for example, products of hydrogenation and refining of petroleum fractions or residual oils, or lubricating oil bases obtained by decomposition.

[0141] As one preferred method, for example, high molecular weight paraffin oil (3a) contains the product of formula C n H 2n+2 The compound referred to. Furthermore, in this invention, the above-mentioned n can be a value corresponding to the weight-average molecular weight of the high molecular weight paraffin oil (3a).

[0142] In addition, as one of the preferred methods, for example, high molecular weight paraffin oil (3a) is liquid at room temperature (23°C).

[0143] <Weight-average molecular weight of high molecular weight paraffin oil (3a)>

[0144] In this invention, the weight-average molecular weight of the high molecular weight paraffin oil (3a) is 1000 or more.

[0145] From the viewpoint of achieving better results with the present invention, the weight-average molecular weight of the above-mentioned high molecular weight paraffin oil (3a) is preferably 1200 to 3000, more preferably 1300 to 2000.

[0146] In this invention, the weight-average molecular weight of paraffin oil refers to the weight-average molecular weight converted from standard polystyrene based on the measured value obtained by gel permeation chromatography (GPC) (the same applies below). The determination conditions for the weight-average molecular weight of the paraffin oil are as follows.

[0147] (Measurement conditions)

[0148] GPC: LC Solution (manufactured by SHIMAZU)

[0149] Detector: SPD-20A (manufactured by SHIMAZU)

[0150] Column: Two MIXED-E (manufactured by Polymer Laboratories) wires connected in series.

[0151] Solvent: Tetrahydrofuran

[0152] Temperature: 40℃

[0153] Flow rate: 0.5 ml / min

[0154] Concentration: 2mg / ml

[0155] Standard sample: polystyrene

[0156] <Low molecular weight paraffin oil (3b)>

[0157] The composition of the present invention contains low molecular weight paraffin oil (3b) with a weight average molecular weight of less than 1000 as the paraffin oil.

[0158] The composition of the present invention achieves an excellent balance of workability, adhesion and disintegration by containing low molecular weight paraffin oil (3b).

[0159] As a low molecular weight paraffin oil (3b), examples include products of hydrogenation and refining of petroleum fractions or residual oils, or lubricating oil bases obtained by decomposition.

[0160] As one preferred method, for example, low molecular weight paraffin oil (3b) contains the following: n H 2n+2 The compound referred to. Furthermore, in this invention, the above-mentioned n can be a value corresponding to the weight-average molecular weight of the low molecular weight paraffin oil (3b).

[0161] In addition, as one of the preferred methods, for example, low molecular weight paraffin oil (3b) is liquid at room temperature (23°C).

[0162] <Weight-average molecular weight of low molecular weight paraffin oil (3b)>

[0163] In this invention, the weight-average molecular weight of the low molecular weight paraffin oil (3b) is preferably 500 or more and less than 11,000, more preferably 700 or more and less than 1,000.

[0164] The method for determining the weight-average molecular weight of low molecular weight paraffin oil (3b) is the same as the method for determining the weight-average molecular weight of paraffin oil described above.

[0165] (Total content of high molecular weight paraffin oil (3a) and low molecular weight paraffin oil (3b))

[0166] From the viewpoint of achieving better results with the present invention, the total content of the above-mentioned high molecular weight paraffin oil (3a) and low molecular weight paraffin oil (3b) relative to 100 parts by weight of the above-mentioned styrene-based thermoplastic elastomer (1a) is preferably 500 to 3000 parts by weight, more preferably 700 to 1500 parts by weight.

[0167] • High molecular weight paraffin oil (3a) / Low molecular weight paraffin oil (3b) (mass ratio B)

[0168] From the viewpoint that the present invention has superior effects (especially workability and heat creep resistance), the mass ratio B (high molecular weight paraffin oil (3a) / low molecular weight paraffin oil (3b)) of the content of the above-mentioned high molecular weight paraffin oil (3a) to the content of the above-mentioned low molecular weight paraffin oil (3b) is preferably 5 / 95 to 95 / 5, more preferably 20 / 80 to 70 / 30, and even more preferably 30 / 70 to 50 / 50.

[0169] (additive)

[0170] The compositions of the present invention may further contain additives as needed. Examples of additives include, for instance, styrene-based thermoplastic elastomers (1a), (1b), thermoplastic elastomers other than ethylene propylene rubber and butyl rubber; antioxidants, UV absorbers, fillers, softeners or plasticizers other than paraffin oils, and reinforcing agents such as hindered phenolic compounds. The amount of additives may be appropriately determined.

[0171] (Manufacturing method)

[0172] There are no particular limitations on the manufacturing method of the compositions of the present invention. For example, they can be manufactured by mixing the above-mentioned necessary components and additives that can be used as needed at a temperature of 150 to 250°C.

[0173] (How to use)

[0174] As an example of using the hot-melt composition of the present invention, the following method can be listed: heating the composition of the present invention to 190-230°C to melt it, applying it to the adherends (e.g., the first component and / or the second component), joining or laminating the adherends to form a bonded body or laminate, and placing the bonded body or laminate at room temperature to cure the composition of the present invention. The material of the second component may be the same as or different from that of the first component.

[0175] Examples of substrates (adhesives) to which the compositions of the present invention can be applied include plastics [e.g., polyolefins such as polypropylene; polycarbonate; (meth)acrylic resins], wood, rubber, glass, and metal.

[0176] As a preferred embodiment, the composition of the present invention can be used in the bonding of polycarbonate resin, (meth)acrylic resin or polypropylene, and in the bonding of polycarbonate resin or (meth)acrylic resin to polypropylene.

[0177] As a method of applying the composition of the present invention to a substrate (adhesive), for example, the method of using a sprayer (applier) can be cited.

[0178] The compositions of the present invention can be used as, for example, hot-melt compositions for lamps. Examples of lamps include automotive lamps (e.g., headlights, rear combination lamps, etc.) and motorcycle lamps. In the case of automotive lamps, for example, the compositions of the present invention can be used in the sealing (bonding) of the lens and housing of the automotive lamp, and in the sealing portion of the lens.

[0179] Example

[0180] The following examples illustrate the invention in detail. However, the invention is not limited to these examples.

[0181] <Preparation of the Composition>

[0182] Using the thermoplastic elastomer and paraffin oil shown in Table 1 below, in the amounts (parts by mass) indicated in Table 1 below, they were placed in a 3L double-arm kneader (manufactured by Spindol Corporation, Japan) and stirred at 200°C for 40 minutes to obtain a mixture. Next, the compound corresponding to tackifier (2) (or (for comparison) polyterpene resin) and antioxidant shown in the table were added to the above mixture, and they were further mixed for 1 hour to produce various hot melt compositions.

[0183] It should be noted that the styrene content of styrene-based thermoplastic elastomers in Table 1 is expressed as "St**%", where % refers to mass.

[0184] <Evaluation>

[0185] The compositions manufactured as described above were evaluated as follows. The results are shown in Table 1.

[0186] (Assignment-based)

[0187] The composition prepared as described above was melted at 220°C for 30 minutes. The viscosity of the composition was measured at 5 rpm using a BF type viscometer (Brookfield type viscometer) with rotor No. 29, in accordance with JIS K 6833-1, and the composition was evaluated.

[0188] • Evaluation criteria for workability

[0189] When the viscosity is below 100 Pa·s, the workability is rated as excellent, and is indicated by "0".

[0190] When the viscosity exceeds 100 Pa·s but is below 150 Pa·s, the workability is rated as slightly excellent, and is denoted as "△".

[0191] On the other hand, when the viscosity exceeds 150 Pa·s, it is evaluated as having poor workability and is indicated as "×".

[0192] (Heat-resistant flowability: vertical flow)

[0193] The composition manufactured as described above was melted at 220°C using a handheld heating gun, and beads with a diameter of 4mm and a length of 50mm were coated onto an aluminum plate. Then, the aluminum plate was placed in an oven at 120°C with the plate upright at 90° for 24 hours, and the drooping of the material (composition) after 24 hours was measured (after 24 hours, with the aluminum plate upright at 90°, the distance the beads droop from the lowest position of the aluminum plate and the attached beads).

[0194] Evaluation criteria for heat resistance and fluidity

[0195] When the drooping distance is less than 5mm, it is evaluated as having excellent heat resistance and fluidity, and is indicated by "○".

[0196] On the other hand, if the drooping distance exceeds 5mm, it is evaluated as having poor heat resistance and fluidity, and is indicated as "×".

[0197] (Seamless / Disintegrable)

[0198] The compositions prepared as described above were heated to 220°C and melted, then coated onto a PP sheet (made of polypropylene, 25mm x 75mm x 3mm thick). After coating, a PC sheet (made of polycarbonate, 25mm x 75mm x 3mm thick) was overlapped on the PP sheet composition in a cross pattern, and the composition was pressed together with an adhesive area of ​​25mm x 25mm until it reached a thickness of 3mm. The mixture was then placed at 20°C and 50% RH for 24 hours to cure, resulting in a test piece. The test piece had a hot-melt composition (adhesive layer) between the PP sheet and the PC sheet.

[0199] For the obtained test pieces, a tensile testing machine was used to perform a tensile test on the PC sheet in a direction perpendicular to the surface of the PP sheet at 20℃ and a tensile speed of 50 mm / min. The peel strength of the test pieces was determined. In addition, the state of the fracture surface after failure (failure mode) was observed visually.

[0200] The peel strength (N) measured for each test piece is shown in Table 1. Furthermore, for the failure mode, cases where the adhesive layer is neatly peeled from the PP sheet are indicated as "○", and cases where the adhesive layer remains on the PP sheet are indicated as "×".

[0201] • Evaluation of the balance between tightness and disintegration

[0202] Under the conditions of a strength (peel strength) of 60-130 N and a failure mode of "0", the product is evaluated as having an excellent balance between adhesion and disintegration.

[0203] Furthermore, when the strength is 70–120 N and the failure mode is “0”, the balance between sealing and disintegration is evaluated as superior. When the strength is 75–90 N and the failure mode is “0”, the balance between sealing and disintegration is evaluated as superior.

[0204] On the other hand, when the strength is less than 60N, the sealing is poor, so it is evaluated as a poor balance between sealing and disintegration.

[0205] In addition, when the strength exceeds 130N, or when the failure mode is "×", the disintegration is poor, and therefore it is evaluated as a poor balance between tightness and disintegration.

[0206] (Volatileness)

[0207] Place 3g of each of the compositions prepared as described above into a test tube, and seal the top of the test tube with a glass plate. Immerse the test tube in an oil bath at 120°C for heating.

[0208] Twenty-four hours after the start of heating, the presence or absence of dirt on the inner surface of the glass plate (the test tube and the part constituting the sealed space) was visually confirmed.

[0209] If the inner surface of the glass plate is free of dirt, it is described as "dirt-free" and evaluated as having excellent resistance to volatilization.

[0210] On the other hand, if dirt is found on the inner surface of the glass plate, it is indicated as "dirty" and evaluated as having excellent volatility resistance.

[0211] (Heat creep resistance)

[0212] The compositions prepared as described above were heated to 220°C and melted, then coated onto a PP sheet (made of polypropylene, 25mm x 75mm x 3mm thick). After coating, a PC sheet (made of polycarbonate, 25mm x 75mm x 3mm thick) was overlapped on the PP sheet composition in a cross pattern, and the compositions were pressed together with an adhesive area of ​​25mm x 25mm until a thickness of 3mm was achieved. The mixture was then cured at 20°C and 50% RH for 24 hours to obtain a test piece. The test piece had a hot-melt composition (adhesive layer) between the PP sheet and the PC sheet.

[0213] For the initial test pieces obtained, the PC board was stretched in a direction perpendicular to the surface of the PP board. The test pieces were fixed with the adhesive layer elongated by 150%, and a heat resistance test was conducted at 60°C for 24 hours in their original state.

[0214] The peeling of the hot melt composition (adhesive layer) in the test pieces (maintained in a fixed state, the same below) after the above heat resistance test was visually confirmed.

[0215] Evaluation criteria for heat creep resistance

[0216] Among the test pieces after the above heat resistance test, those in which the hot melt composition (adhesive layer) has not completely peeled off from the substrate, or in which the area of ​​the hot melt composition bonded to the PP board and PC board is more than 80% of the total area of ​​the bonded surface (25mm in length × 25mm in width, the same below), are evaluated as having the best heat creep resistance (the highest retention rate of seal after heating), and are indicated by "◎".

[0217] When the area of ​​the hot melt composition bonded to PP and PC sheets is more than 60% but less than 80% of the total bonding surface, it is evaluated as having excellent heat creep resistance (very high seal retention rate after heating), and is indicated as "0".

[0218] When the area of ​​the hot melt composition bonded to the PP and PC sheets is more than 30% but less than 60% of the total bonding surface, it is evaluated as having slightly better heat creep resistance (slightly higher seal retention rate after heating), which is denoted as "△".

[0219] On the other hand, if the area of ​​the hot melt composition bonded to the PP and PC boards is less than 30% of the total bonding surface, it is evaluated as having poor heat creep resistance (low seal retention rate after heating) and is indicated as "×".

[0220]

[0221]

[0222] The details of each component shown in Table 1 are as follows.

[0223] <Styrene-based thermoplastic elastomers (1a)>

[0224] • Styrene-based thermoplastic elastomer (1a-1): SEEPS (St content 30% by mass, Mw 390,000). Trade name SEPTON 4077, manufactured by Kuraray Co., Ltd.

[0225] • Comparison with styrene-based thermoplastic elastomer 1: SEEPS (St content 30% by mass, Mw 250,000). Trade name SEPTON 4055, manufactured by Kuraray Co., Ltd.

[0226] • Comparison with styrene-based thermoplastic elastomer 2: SEBS (St content 30% by mass, Mw 110,000). Trade name Kraton G1650, manufactured by Kuraray Co., Ltd.

[0227] <Styrene-based thermoplastic elastomers (1b)>

[0228] • Styrene-based thermoplastic elastomer (1b-1): SEPS (St content 13% by mass, Mw 120,000). Trade name SEPTON2063, manufactured by Kuraray Co., Ltd.

[0229] • Styrene-based thermoplastic elastomer (1b-2): SEBS (St content 12% by mass, Mw 180,000). Trade name: Tuftec H-1221, manufactured by Asahi Kasei Corporation.

[0230] • Comparison with styrene-based thermoplastic elastomer 3: SEPS (St content 65% by mass, Mw 90,000). Trade name SEPTON2104, manufactured by Kuraray Co., Ltd.

[0231] Furthermore, the styrene-based thermoplastic elastomers 1 to 3 used in the above comparisons are not equivalent to the styrene-based thermoplastic elastomers (1a) and (1b) in this invention.

[0232] <Olefin-based thermoplastic elastomers (1c)>

[0233] • Olefin-based thermoplastic elastomer (1c-1): Ethylene-propylene rubber. Trade name: Mitsui EPT0045, manufactured by Mitsui Chemicals Co., Ltd. No third component (as a monomer). Mw: 350,000. Rubber formed solely from ethylene and propylene.

[0234] • Olefin-based thermoplastic elastomer (1c-2): Butyl rubber. Trade name: Butyl 365, manufactured by JSR Corporation. Mw: 440,000

[0235] <<Tackifying Materials (2)>>

[0236] <Aromatic Petroleum Resins (2a)>

[0237] • Aromatic petroleum resins (2a-1): Aromatic hydrocarbon resins (styrene-based hydrocarbon resins). Trade name: FMR0150, manufactured by Mitsui Chemicals Co., Ltd.

[0238] <Terpene Phenolic Resin (2b)>

[0239] • Terpene phenol resin (2b-1): Trade name YS Polyster U115, manufactured by Yasuhara Chemical Co., Ltd. A non-hydrogenated terpene phenol resin.

[0240] • (For comparison) Polyterpene resin: A resin polymerized solely (100%) of terpene monomers. Trade name: YS RESINPX1150, manufactured by Yasuharake Mikaru Co., Ltd.

[0241] <Amorphous polyalphaolefin (2c)>

[0242] • Amorphous polyalphaolefin (2c-1): APAO (propylene / butene-1 copolymer). Trade name RT2780, manufactured by Rextac. Mw70,000

[0243] • Amorphous polyalphaolefin (2c-2): APAO (propylene / ethylene copolymer). Trade name RT2585, manufactured by Rextac. Mw60,000

[0244] <High molecular weight paraffin oil (3a)>

[0245] • High molecular weight paraffin oil (3a-1): High molecular weight paraffin oil. Weight average molecular weight 1500. Trade name PW-380, manufactured by Idemitsu Kosan Co., Ltd.

[0246] <Low molecular weight paraffin oil (3b)>

[0247] • Low molecular weight paraffin oil (3b-1): Low molecular weight paraffin oil. Weight average molecular weight 900. Trade name PW-90, manufactured by Idemitsu Kosan Co., Ltd.

[0248] (Anti-aging agents)

[0249] • Antioxidant: Hindered phenolic compound. Trade name: Irganox 1010, manufactured by BASF.

[0250] As can be seen from the results shown in Table 1, Comparative Example 1, which does not contain the specific St-based elastomer (1a) but instead contains the comparative styrene-based thermoplastic elastomer 1, has poor heat resistance and flowability.

[0251] Comparative Example 2, which does not contain the specific St-based elastomer (1b), has poor workability and poor adhesion, resulting in a poor balance between adhesion and disintegration.

[0252] Comparative Example 3, which does not contain a specific St-based elastomer (1b) but instead contains a comparative styrene-based thermoplastic elastomer 3, has poor heat resistance and flowability, poor disintegration properties, and therefore a poor balance between adhesion and disintegration.

[0253] Although Comparative Example 4, which does not contain a specific olefin-based elastomer (1c), has an excellent balance between adhesion and disintegration, it has poor workability and heat creep resistance.

[0254] Comparative Example 5, which does not contain aromatic petroleum resin (2a), has poor adhesion and disintegration properties, resulting in a poor balance between adhesion and disintegration.

[0255] Comparative Example 6, which does not contain terpene phenol resin (2b), has poor workability and disintegration properties, resulting in a poor balance between adhesion and disintegration.

[0256] Comparative Example 7, which does not contain terpene phenol resin (2b) and instead contains polyterpene resin, suffers from poor workability and poor adhesion, resulting in a poor balance between adhesion and disintegration.

[0257] Comparative Example 8, which does not contain amorphous polyα-olefin (2c), has a poor balance between tightness and disintegration due to its poor adhesion.

[0258] Comparative Example 9, which does not contain high molecular weight paraffin oil (3a), has poor heat flowability and volatility resistance.

[0259] Comparative Example 10, which does not contain specific St-based elastomers (1b), specific olefin-based elastomers (1c), and terpene phenolic resins (2b), exhibits poor heat creep resistance.

[0260] Comparative Example 11, which does not contain specific St-based elastomers (1b), specific olefin-based elastomers (1c), terpene phenolic resins (2b), and amorphous polyα-olefins (2c), and contains polyterpene resins instead of terpene phenolic resins (2b), has poor workability, poor adhesion, and therefore a poor balance between adhesion and disintegration, as well as poor heat creep resistance.

[0261] Comparative Example 12, which does not contain specific St-based elastomers (1b), specific olefin-based elastomers (1c), and terpene phenolic resins (2b), and contains polyterpene resins instead of terpene phenolic resins (2b), suffers from poor workability, poor adhesion, poor balance between adhesion and disintegration, and poor heat creep resistance.

[0262] Comparative Example 13, which does not contain specific St-based elastomers (1b) and specific olefin-based elastomers (1c), has poor workability and heat creep resistance.

[0263] Comparative Example 14, which does not contain specific olefin elastomers (1c), terpene phenolic resins (2b), amorphous polyalphaolefins (2c), and low molecular weight paraffin oils (3b), exhibits poor heat creep resistance.

[0264] Comparative Example 15, which does not contain a specific St-based elastomer (1a), but instead contains a comparative styrene-based thermoplastic elastomer 2, does not contain a specific St-based elastomer (1b), amorphous poly-α-olefin (2c), and low molecular weight paraffin oil (3b), exhibits excessively strong adhesion that prevents disintegration, resulting in a poor balance between adhesion and disintegration.

[0265] Comparative Example 16, which does not contain a specific St-based elastomer (1b) but instead contains a comparative styrene-based thermoplastic elastomer 2, has poor heat resistance and flowability.

[0266] In comparison, the compositions of the present invention exhibit superior workability, heat-resistant flowability, a balance between adhesion and disintegration, volatility resistance, and heat creep resistance.

Claims

1. A hot-melt composition comprising a styrene-based thermoplastic elastomer with a weight average molecular weight of 300,000 or more (1a), a styrene-based thermoplastic elastomer with a weight average molecular weight of less than 300,000 and a styrene content of less than 20% by mass (1b), and an olefin-based thermoplastic elastomer comprising ethylene propylene rubber and / or butyl rubber (1c) as a thermoplastic elastomer (1); comprising an aromatic petroleum resin (2a), a terpene phenolic resin (2b), and an amorphous polyα-olefin (2c) as a tackifying material (2); and further comprising: a high molecular weight paraffin oil with a weight average molecular weight of 1,000 or more (3a); and a low molecular weight paraffin oil with a weight average molecular weight of less than 1,000 (3b). Relative to 100 parts by mass of the styrene-based thermoplastic elastomer (1a). The content of the styrene-based thermoplastic elastomer (1b) is 10 to 50 parts by weight. The content of the olefin-based thermoplastic elastomer (1c) is 30 to 70 parts by mass. The total content of the aromatic petroleum resin (2a) and the terpene phenol resin (2b) is 200-600 parts by weight. The content of the amorphous polyα-olefin (2c) is 1 to 20 parts by mass. The total content of the high molecular weight paraffin oil (3a) and the low molecular weight paraffin oil (3b) is 500 to 3000 parts by mass.

2. The hot-melt composition according to claim 1, wherein, The content of the styrene-based thermoplastic elastomer (1b) is 20 to 40 parts by mass relative to 100 parts by mass of the styrene-based thermoplastic elastomer (1a).

3. The hot-melt composition according to claim 1 or 2, wherein, The content of the olefin-based thermoplastic elastomer (1c) is 40 to 60 parts by mass relative to 100 parts by mass of the styrene-based thermoplastic elastomer (1a).

4. The hot-melt composition according to claim 1 or 2, wherein, The styrene content of the styrene-based thermoplastic elastomer (1a) is 25 to 40% by mass of the styrene-based thermoplastic elastomer (1a).

5. The hot-melt composition according to claim 3, wherein, The styrene content of the styrene-based thermoplastic elastomer (1a) is 25 to 40% by mass of the styrene-based thermoplastic elastomer (1a).

6. The hot-melt composition according to any one of claims 1, 2, and 5, wherein, The styrene-based thermoplastic elastomer (1a) contains SEEPS.

7. The hot-melt composition according to claim 3, wherein, The styrene-based thermoplastic elastomer (1a) contains SEEPS.

8. The hot-melt composition according to claim 4, wherein, The styrene-based thermoplastic elastomer (1a) contains SEEPS.

9. The hot-melt composition according to any one of claims 1, 2, 5, 7, and 8, wherein, The total content of the aromatic petroleum resin (2a) and the terpene phenol resin (2b) is 200 to 500 parts by weight relative to 100 parts by weight of the styrene-based thermoplastic elastomer (1a).

10. The hot-melt composition according to claim 3, wherein, The total content of the aromatic petroleum resin (2a) and the terpene phenol resin (2b) is 200 to 500 parts by weight relative to 100 parts by weight of the styrene-based thermoplastic elastomer (1a).

11. The hot-melt composition according to claim 4, wherein, The total content of the aromatic petroleum resin (2a) and the terpene phenol resin (2b) is 200 to 500 parts by weight relative to 100 parts by weight of the styrene-based thermoplastic elastomer (1a).

12. The hot-melt composition according to claim 6, wherein, The total content of the aromatic petroleum resin (2a) and the terpene phenol resin (2b) is 200 to 500 parts by weight relative to 100 parts by weight of the styrene-based thermoplastic elastomer (1a).

13. The hot-melt composition according to any one of claims 1, 2, 5, 7, 8, 10-12, wherein, The content of the amorphous polyα-olefin (2c) is 1 to 10 parts by mass relative to 100 parts by mass of the styrene-based thermoplastic elastomer (1a).

14. The hot-melt composition according to claim 3, wherein, The content of the amorphous polyα-olefin (2c) is 1 to 10 parts by mass relative to 100 parts by mass of the styrene-based thermoplastic elastomer (1a).

15. The hot-melt composition according to claim 4, wherein, The content of the amorphous polyα-olefin (2c) is 1 to 10 parts by mass relative to 100 parts by mass of the styrene-based thermoplastic elastomer (1a).

16. The hot-melt composition according to claim 6, wherein, The content of the amorphous polyα-olefin (2c) is 1 to 10 parts by mass relative to 100 parts by mass of the styrene-based thermoplastic elastomer (1a).

17. The hot-melt composition according to claim 9, wherein, The content of the amorphous polyα-olefin (2c) is 1 to 10 parts by mass relative to 100 parts by mass of the styrene-based thermoplastic elastomer (1a).

18. The hot-melt composition according to any one of claims 1, 2, 5, 7, 8, 10-12, 14-17, wherein, The total content of the high molecular weight paraffin oil (3a) and the low molecular weight paraffin oil (3b) is 700 to 1500 parts by weight relative to 100 parts by weight of the styrene-based thermoplastic elastomer (1a).

19. The hot-melt composition according to claim 3, wherein, The total content of the high molecular weight paraffin oil (3a) and the low molecular weight paraffin oil (3b) is 700 to 1500 parts by weight relative to 100 parts by weight of the styrene-based thermoplastic elastomer (1a).

20. The hot-melt composition according to claim 4, wherein, The total content of the high molecular weight paraffin oil (3a) and the low molecular weight paraffin oil (3b) is 700 to 1500 parts by weight relative to 100 parts by weight of the styrene-based thermoplastic elastomer (1a).

21. The hot-melt composition according to claim 6, wherein, The total content of the high molecular weight paraffin oil (3a) and the low molecular weight paraffin oil (3b) is 700 to 1500 parts by weight relative to 100 parts by weight of the styrene-based thermoplastic elastomer (1a).

22. The hot-melt composition according to claim 9, wherein, The total content of the high molecular weight paraffin oil (3a) and the low molecular weight paraffin oil (3b) is 700 to 1500 parts by weight relative to 100 parts by weight of the styrene-based thermoplastic elastomer (1a).

23. The hot-melt composition according to claim 13, wherein, The total content of the high molecular weight paraffin oil (3a) and the low molecular weight paraffin oil (3b) is 700 to 1500 parts by weight relative to 100 parts by weight of the styrene-based thermoplastic elastomer (1a).

24. The hot-melt composition according to any one of claims 1, 2, 5, 7, 8, 10-12, 14-17, 19-23, wherein, The mass ratio of the content of the high molecular weight paraffin oil (3a) to the content of the low molecular weight paraffin oil (3b) (high molecular weight paraffin oil (3a) / low molecular weight paraffin oil (3b)) is 5 / 95 to 95 / 5.

25. The hot-melt composition according to claim 3, wherein, The mass ratio of the content of the high molecular weight paraffin oil (3a) to the content of the low molecular weight paraffin oil (3b) (high molecular weight paraffin oil (3a) / low molecular weight paraffin oil (3b)) is 5 / 95 to 95 / 5.

26. The hot-melt composition according to claim 4, wherein, The mass ratio of the content of the high molecular weight paraffin oil (3a) to the content of the low molecular weight paraffin oil (3b) (high molecular weight paraffin oil (3a) / low molecular weight paraffin oil (3b)) is 5 / 95 to 95 / 5.

27. The hot-melt composition according to claim 6, wherein, The mass ratio of the content of the high molecular weight paraffin oil (3a) to the content of the low molecular weight paraffin oil (3b) (high molecular weight paraffin oil (3a) / low molecular weight paraffin oil (3b)) is 5 / 95 to 95 / 5.

28. The hot-melt composition according to claim 9, wherein, The mass ratio of the content of the high molecular weight paraffin oil (3a) to the content of the low molecular weight paraffin oil (3b) (high molecular weight paraffin oil (3a) / low molecular weight paraffin oil (3b)) is 5 / 95 to 95 / 5.

29. The hot-melt composition according to claim 13, wherein, The mass ratio of the content of the high molecular weight paraffin oil (3a) to the content of the low molecular weight paraffin oil (3b) (high molecular weight paraffin oil (3a) / low molecular weight paraffin oil (3b)) is 5 / 95 to 95 / 5.

30. The hot-melt composition according to claim 18, wherein, The mass ratio of the content of the high molecular weight paraffin oil (3a) to the content of the low molecular weight paraffin oil (3b) (high molecular weight paraffin oil (3a) / low molecular weight paraffin oil (3b)) is 5 / 95 to 95 / 5.

31. The hot melt composition according to any one of claims 1, 2, 5, 7, 8, 10-12, 14-17, 19-23, 25-30, for use in automotive lamps.

32. The hot-melt composition according to claim 3, used in automotive lamps.

33. The hot-melt composition according to claim 4, used in automotive lamps.

34. The hot-melt composition according to claim 6, used in automotive lamps.

35. The hot-melt composition according to claim 9, used in automotive lamps.

36. The hot-melt composition according to claim 13, used in automotive lamps.

37. The hot-melt composition according to claim 18, used in automotive lamps.

38. The hot-melt composition according to claim 24, used in automotive lamps.

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