Hot-melt adhesive composition

Abstract

To provide a hot-melt adhesive composition excellent in heat resistance, adhesive property and coating adaptability.SOLUTION: A hot-melt adhesive composition contains: a thermoplastic block copolymer component (A) as a copolymer of vinyl aromatic hydrocarbon and a conjugated diene compound; two kinds of tackifier resin components (B) having different hydroxyl values; and a non-aromatic liquid plasticizer component (C). The thermoplastic block copolymer component (A) has 20 wt.% or more of a vinyl aromatic hydrocarbon component, a diblock percentage content of 60 wt.% or less, and the tackifier resin component (B) contains 10-90 wt.% of a non-aromatic low hydroxyl value tackifier resin component (B1) with a hydroxyl value of less than 100 mgKOH / g, and 90-10 wt.% of a high hydroxyl value tackifier resin component (B2) with a hydroxyl value of 100 mgKOH / g or more.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a hot melt pressure sensitive adhesive composition. [Background technology]

[0002] In recent years, the technique of joining components used in assembly using hot-melt adhesives has been widely used in various industrial fields, such as the electrical and electronic fields, the automotive field, and the construction and civil engineering fields. For example, in the electrical and electronic fields, hot-melt adhesives containing thermoplastic elastomers as their main component are used to join plastics, metals, glass, etc. in a variety of applications, such as refrigerators, televisions, mobile phones, personal computers, rice cookers, copiers, and game consoles (see, for example, Patent Document 1 below).

[0003] In the above applications, hot-melt pressure-sensitive adhesives are required to have high adhesive properties in high-temperature environments because they are used to bond highly polar components such as metals and are used in environments where the components are prone to become hot. Furthermore, because hot-melt pressure-sensitive adhesives are used by being heated and melted using equipment such as an applicator, they are required to have excellent heat resistance, adhesive properties, and also excellent applicability. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 6006032 Summary of the Invention [Problem to be solved by the invention]

[0005] The present invention was completed under such background technology, and an object of the present invention is to provide a hot melt pressure-sensitive adhesive composition that is excellent in heat resistance, adhesiveness, and applicability. [Means for solving the problem]

[0006] Thus, according to the present invention, the following inventions are provided.

[0007] (1) A hot melt pressure-sensitive adhesive composition comprising 100 parts by weight of a thermoplastic block copolymer component (A), which is a copolymer of a vinyl-based aromatic hydrocarbon and a conjugated diene compound, 50 to 110 parts by weight of a tackifier resin component (B) having a softening point of 120°C to 160°C, and 5 to 30 parts by weight of a non-aromatic liquid plasticizer component (C), wherein the thermoplastic block copolymer component (A) contains 20% by weight or more of a vinyl-based aromatic hydrocarbon component and a diblock content of 60% by weight or less, and the tackifier resin component (B) comprises 10 to 90% by weight of a non-aromatic low-hydroxyl value tackifier resin component (B1) having a hydroxyl value of less than 100 mgKOH / g and 90 to 10% by weight of a high-hydroxyl value tackifier resin component (B2) having a hydroxyl value of 100 mgKOH / g or more. (2) The hot melt pressure-sensitive adhesive composition according to (1), wherein the vinyl aromatic hydrocarbon of the thermoplastic block copolymer component (A) is styrene. (3) The hot melt pressure-sensitive adhesive composition according to (1) or (2), wherein the conjugated diene compound of the thermoplastic block copolymer component (A) is isoprene. (4) The hot melt pressure-sensitive adhesive composition according to any one of (1) to (3), wherein the thermoplastic block copolymer component (A) has a weight average molecular weight of 200,000 or less. (5) The hot melt pressure-sensitive adhesive composition according to any one of (1) to (4), wherein the high hydroxyl value tackifying resin component (B2) is a phenol-modified tackifying resin. (6) The hot melt pressure-sensitive adhesive composition according to any one of (1) to (5), wherein the non-aromatic liquid plasticizer component (C) is a mineral oil or synthetic oil having a pour point of −10° C. or lower. (7) The hot melt pressure-sensitive adhesive composition according to any one of (1) to (6), which has a 180° peel adhesion strength of 25 N / 25 mm or more at 23°C and 60°C. (8) The hot melt pressure-sensitive adhesive composition according to any one of (1) to (7), which is intended for use in electrical appliances, communication devices, automobile parts, and construction and civil engineering parts. [Effects of the Invention]

[0008] According to the hot melt pressure-sensitive adhesive composition of the present invention, it is possible to provide a hot melt pressure-sensitive adhesive composition that is excellent in heat resistance and adhesiveness, and also in applicability. DETAILED DESCRIPTION OF THE INVENTION

[0009] The present invention will be described in detail below. Note that the present invention is not limited to the following embodiments, and various modifications can be made within the scope of the gist of the present invention.

[0010] In this specification, "aromatic" refers to a compound containing a cyclic unsaturated organic compound component, such as benzene, naphthalene, or anthracene, as a constituent component, and "non-aromatic" refers to a compound not containing any of the aforementioned cyclic unsaturated organic compound components as a constituent component.

[0011] In this specification, the term "styrene content" refers to the proportion of styrene blocks relative to the total amount of a thermoplastic block copolymer, which is a copolymer of a vinyl aromatic hydrocarbon and a conjugated diene compound, when the vinyl aromatic hydrocarbon component contained in the thermoplastic block copolymer is styrene, and the term "diblock content" refers to the proportion of diblock units represented by A-B type contained in a thermoplastic block copolymer, which is a copolymer of a vinyl aromatic hydrocarbon and a conjugated diene compound, which is represented by A-B-A type.

[0012] <Hot melt pressure-sensitive adhesive composition of the present invention> The hot-melt pressure-sensitive adhesive composition of the present invention contains a thermoplastic block copolymer component (A) which is a copolymer of a vinyl aromatic hydrocarbon and a conjugated diene compound, two tackifying resin components (B) having different hydroxyl values, and a non-aromatic liquid plasticizer component (C). The components (A) to (C) are described in detail below.

[0013] <Thermoplastic block copolymer component (A), which is a copolymer of a vinyl aromatic hydrocarbon and a conjugated diene compound> In the present invention, a thermoplastic block copolymer component (A), which is a copolymer of a vinyl aromatic hydrocarbon and a conjugated diene compound, is used as the main component constituting the hot melt pressure-sensitive adhesive composition. Due to the physical crosslinking of the vinyl aromatic hydrocarbon polymer block, the thermoplastic block copolymer has high cohesive strength suitable for adhesive materials, and because it plasticizes and flows when heated, it can also be suitably used in hot melt pressure-sensitive adhesive compositions.

[0014] The thermoplastic block copolymer component (A), a copolymer of a vinyl aromatic hydrocarbon and a conjugated diene compound used in the present invention, includes vinyl aromatic hydrocarbons of the A-B-A type. Specific examples include styrene-based thermoplastic elastomers, such as styrene-butadiene-styrene block copolymers (S-B-S), styrene-isoprene-styrene block copolymers (S-I-S), and styrene-isobutylene-styrene block copolymers (S-IB-S), as well as hydrogenated versions of these block copolymers, such as styrene-ethylene-butadiene-styrene block copolymers (S-E-B-S), styrene-ethylene-propylene-styrene block copolymers (S-E-P-S), and carboxyl-modified styrene-based thermoplastic elastomers. Furthermore, the styrene block may contain, in addition to styrene, a copolymer of an aromatic vinyl compound containing styrene and α-methylstyrene, etc. Among these styrene-based thermoplastic elastomers, styrene-isoprene-styrene block copolymers are preferred.

[0015] Thermoplastic block copolymer component (A), which is a copolymer of a vinyl aromatic hydrocarbon and a conjugated diene compound, is available in linear or radial structures, and in those in which the polymer blocks A at both ends are symmetrical or asymmetrical. These can be used depending on the intended purpose, such as heat resistance or adhesiveness.

[0016] The block copolymer component (A) contains a vinyl aromatic hydrocarbon component in an amount of 20% by weight or more, preferably 25 to 50% by weight, based on the total amount of the block copolymer component (A), and has a diblock content of 60% by weight or less, which tends to result in a hot melt pressure-sensitive adhesive composition with an excellent balance between heat resistance and adhesiveness.

[0017] The thermoplastic block copolymer component (A), which is a copolymer of the vinyl aromatic hydrocarbon and a conjugated diene compound, preferably has a weight-average molecular weight (Mw) of 200,000 or less. If the weight-average molecular weight is too high, the fluidity is poor, making it impossible to extrude from equipment such as an applicator, or the amount extruded per hour is significantly low. Therefore, the weight-average molecular weight of the thermoplastic block copolymer component (A) is preferably within the above range, and more preferably 150,000 or less.

[0018] The weight-average molecular weight refers to a value measured by gel permeation chromatography (GPC) using tetrahydrofuran as a solvent. Specifically, the value can be measured using the following equipment and measurement method. An Alliance HPLC system (Waters) is used as the chromatograph, a differential refractive index detector (Waters) with RI is used as the detector, and an HSP series (Waters) is used as the GPC column. A sample is dissolved in tetrahydrofuran and run at a flow rate of 0.30 ml / min and a measurement temperature of 40°C. The molecular weight is converted using a calibration curve based on polystyrene (Tosoh Corporation) to determine the weight-average molecular weight.

[0019] In the present invention, the thermoplastic block copolymer component (A), which is a copolymer of the above-mentioned vinyl aromatic hydrocarbon and a conjugated diene compound, may be used alone or in combination, so long as the vinyl aromatic hydrocarbon component, i.e., styrene content, is 20% or more and the diblock content is 60% or less, relative to the total amount of the block copolymer components.

[0020] Commercially available thermoplastic block copolymer component (A), which is a copolymer of a vinyl aromatic hydrocarbon and a conjugated diene compound, includes, for example, Quintac 3280 (manufactured by Zeon Corporation, styrene content 25%, diblock content 17%, weight average molecular weight 135,000, styrene-isoprene-styrene block copolymer, linear structure), Quintac 3190 (manufactured by Zeon Corporation, styrene content 30%, diblock content 60%, weight average molecular weight 125,000, styrene-isoprene-styrene block copolymer, asymmetric linear structure), Quintac 3390 (manufactured by Zeon Corporation, styrene content 48%, diblock content 0%, weight average molecular weight 150,000, styrene-isoprene-styrene block copolymer, asymmetric linear structure), and Kraton D1164 (Kraton, styrene content 29%, diblock content 0%, weight average molecular weight 120,000, styrene-isoprene-styrene block copolymer, linear structure), TR2500 (ENEOS, styrene content 35%, diblock content 40%, weight average molecular weight 125,000, styrene-butadiene-styrene block copolymer, radial structure), TR2787 (ENEOS, styrene content 30%, diblock content 15%, weight average molecular weight 115,000, styrene-butadiene-styrene block copolymer, linear structure), Tuftec H1041 (Asahi Kasei, styrene content 30%, weight average molecular weight 90,000, styrene-ethylene-butadiene-styrene block copolymer, linear structure), Kraton Examples of such block copolymers include, but are not limited to, G1642H (manufactured by Kraton, styrene content 20%, weight average molecular weight 125,000, styrene-ethylene-butadiene-styrene block copolymer, linear structure) and Septon 2104 (manufactured by Kuraray, styrene content 65%, weight average molecular weight 90,000, styrene-ethylene-propylene-styrene block copolymer, linear structure). Such A-B-A type block copolymers can be used as needed within a range that does not impair the required performance, and two or more types may be used in combination. <Tackifying resin component (B)> In the hot melt pressure-sensitive adhesive composition of the present invention, the tackifying resin component (B) comprises a non-aromatic low-hydroxyl value tackifying resin component (B1) having a hydroxyl value of less than 100 mgKOH / g and a high-hydroxyl value tackifying resin component (B2) having a hydroxyl value of 100 mgKOH / g or more, and is blended in an amount of 50 to 110 parts by weight per 100 parts by weight of the thermoplastic block copolymer component (A). This provides the pressure-sensitive adhesive composition with suitable adhesion and a good balance of good adhesion to polar substrates and metals and heat resistance, making it suitable for use in electrical appliances, communications equipment, automotive parts, and construction and civil engineering parts.

[0021] The softening point of the tackifier resin component (B) is 120°C to 160°C. A softening point in this range provides excellent applicability, inhibits a decrease in cohesive strength caused by the tackifier resin component, and improves the heat resistance of the hot-melt pressure-sensitive adhesive composition. From the above viewpoints, the softening point is more preferably in the range of 125 to 145°C.

[0022] [Non-aromatic low-hydroxyl value tackifying resin component (B1) with a hydroxyl value of less than 100 mgKOH / g] By using the non-aromatic low-hydroxyl value tackifying resin component (B1) having a hydroxyl value of less than 100 mgKOH / g, the melt viscosity can be reduced and the adhesive strength can be improved.

[0023] In the present invention, the content of the non-aromatic low-hydroxyl value tackifying resin component (B1) having a hydroxyl value of less than 100 mgKOH / g is 10 to 90 wt % relative to the total amount of the tackifying resin component (B). By setting it within this range, it is easy to achieve a balance between adhesive performance and cohesive strength. From the above viewpoints, the content of the non-aromatic low-hydroxyl value tackifying resin component (B1) is more preferably 30 to 80 wt %, and in particular, when it is 40 to 70 wt %, better heat resistance, adhesiveness, and applicability can be achieved.

[0024] The non-aromatic low-hydroxyl value tackifying resin component (B1) is not particularly limited as long as it has a hydroxyl value of less than 100 mgKOH / g and does not contain aromatics, and petroleum-based tackifying resins, natural tackifying resins, and copolymer resins or modified resins thereof can be used. Specific examples include those primarily composed of a homopolymer of an aliphatic petroleum resin, those primarily composed of a homopolymer of an alicyclic petroleum resin, those primarily composed of a homopolymer of a fully hydrogenated aromatic petroleum resin, those primarily composed of a homopolymer of a dicyclopentadiene petroleum resin, those primarily composed of a homopolymer of a terpene resin, and even those primarily composed of a copolymer containing two or more of these resins in the monomer composition.

[0025] Examples of the non-aromatic low hydroxyl value tackifying resin component (B1) having a hydroxyl value of less than 100 mgKOH / g include YS Resin PX1250 (manufactured by Yasuhara Chemical Co., Ltd., terpene resin, softening point 125°C, hydroxyl value 0 mgKOH / g), Arcon P-140 (manufactured by Arakawa Chemical Industries, Ltd., fully hydrogenated aromatic petroleum resin, softening point 140°C, hydroxyl value 0 mgKOH / g), Arcon P-125 (manufactured by Arakawa Chemical Industries, Ltd., fully hydrogenated aromatic petroleum resin, softening point 140°C, hydroxyl value 0 mgKOH / g), and Arcon P-125 (manufactured by Arakawa Chemical Industries, Ltd., fully hydrogenated aromatic petroleum resin, softening point 140°C, hydroxyl value 0 mgKOH / g). Aromatic petroleum resin, softening point 125°C, hydroxyl value 0mgKOH / g), Imarv P-140 (Idemitsu Kosan Co., Ltd., hydrogenated dicyclopentadiene / fully hydrogenated aromatic copolymer petroleum resin, softening point 140°C, hydroxyl value 0mgKOH / g), Imarv P-125 (Idemitsu Kosan Co., Ltd., hydrogenated dicyclopentadiene / fully hydrogenated aromatic copolymer petroleum resin, softening point 125°C, hydroxyl value 0mgKOH / g), Escorez Examples of suitable tackifying resin components include, but are not limited to, 5340 (manufactured by ExxonMobil, hydrogenated dicyclopentadiene-based petroleum resin, softening point 140°C, hydroxyl value 0 mgKOH / g) and T-REZ HA125 (manufactured by ENEOS Corporation, hydrogenated dicyclopentadiene-based petroleum resin, softening point 125°C, hydroxyl value 0 mgKOH / g). Such non-aromatic low-hydroxyl value tackifying resin components having a hydroxyl value of less than 100 mgKOH / g can be used as needed within a range that does not impair the required performance, and two or more types may be used in combination.

[0026] [High hydroxyl value tackifying resin component (B2) with a hydroxyl value of 100 mgKOH / g or more] The high-hydroxyl value tackifying resin component (B2) having a hydroxyl value of 100 mgKOH / g or more has a hydroxyl value in this range, which improves adhesion to polar substrates and metals and also improves the heat resistance of the hot-melt pressure-sensitive adhesive composition. From the above viewpoints, the hydroxyl value is preferably 110 to 200 mgKOH / g, and more preferably 120 to 160 mgKOH / g.

[0027] In the present invention, the content of the high hydroxyl value tackifying resin component (B2) having a hydroxyl value of 100 mgKOH / g or more is 10 to 90% by weight based on the total amount of the tackifying resin component (B). By setting it in this range, it is easy to achieve a balance between heat resistance and heat stability. From the above viewpoint, the content of the high hydroxyl value tackifying resin component (B2) is more preferably 20 to 70% by weight, and in particular, when it is 30 to 60 parts by weight, better heat resistance and heat stability can be achieved.

[0028] The high hydroxyl value tackifying resin component (B2) is, for example, a phenol-modified tackifying resin, and has excellent adhesiveness and heat resistance, but the high hydroxyl value tackifying resin component (B2) may be composed of a material other than a phenol-modified tackifying resin, as long as the material has excellent adhesiveness and heat resistance.

[0029] Examples of the high hydroxyl value tackifying resin component (B2) include those primarily composed of a phenolic resin homopolymer, those primarily composed of a terpene-phenol copolymer resin, those primarily composed of a rosin resin homopolymer, those primarily composed of a coumarone-indene resin homopolymer, those primarily composed of a ketone resin homopolymer, and even those primarily composed of a copolymer containing two or more of these resins in the monomer composition. Among these high hydroxyl value tackifying resin components (B2), those primarily composed of a terpene-phenol copolymer resin are preferred from the viewpoints of adhesive strength and compatibility with the thermoplastic block copolymer component (A).

[0030] Examples of terpene phenol copolymer resins include copolymers of terpenes and phenols, and those that mainly consist of phenol-modified terpene homopolymers or copolymers of terpenes (phenol-modified terpene resins).Examples of the above-mentioned terpenes include those that mainly consist of homopolymers of copolymers of natural terpenes, those that mainly consist of homopolymers of three-dimensional polymers of natural terpenes, those that mainly consist of homopolymers of terpene resins, and those that mainly consist of copolymers that contain two or more of these resin groups in the monomer composition.

[0031] Examples of the high hydroxyl value tackifying resin component (B2) having a hydroxyl value of 100 mgKOH / g or more include YS Polystar K125 (manufactured by Yasuhara Chemical Co., Ltd., terpene phenol resin, softening point 125°C, hydroxyl value 200 mgKOH / g), YS Polystar N125 (manufactured by Yasuhara Chemical Co., Ltd., terpene phenol resin, softening point 125°C, hydroxyl value 160 mgKOH / g), YS Polystar G125 (manufactured by Yasuhara Chemical Co., Ltd., terpene phenol resin, softening point 125°C, hydroxyl value 140 mgKOH / g), YS Polystar S145 (manufactured by Yasuhara Chemical Co., Ltd., terpene phenol resin, softening point 145°C, hydroxyl value 100 mgKOH / g), and Sylvares Examples of suitable tackifying resin components include, but are not limited to, TP2040HM (manufactured by Kraton, terpene phenol resin, softening point 125°C, hydroxyl value 140 mgKOH / g) and Sylvares TP7042 (manufactured by Kraton, terpene phenol resin, softening point 145°C, hydroxyl value 100 mgKOH / g). A tackifying resin component with a high hydroxyl value of 100 mgKOH / g or more can be used as needed within a range that does not impair the required performance, and two or more types may be used in combination.

[0032] [Aromatic low-hydroxyl value tackifying resin component (B3) with a hydroxyl value of less than 100 mgKOH / g] In the tackifier resin component (B) of the present invention, one or more aromatic low-hydroxyl value tackifier resin components (B3) selected from various known tackifier resins may be used in combination with the non-aromatic low-hydroxyl value tackifier resin component (B1) and the high-hydroxyl value tackifier resin component (B2), provided that the non-aromatic low-hydroxyl value tackifier resin component (B1) and the high-hydroxyl value tackifier resin component (B2) each satisfy the above-mentioned ranges. When used in combination, from the viewpoint of a balance between heat resistance, adhesiveness, and coatability, the content of the aromatic low-hydroxyl value tackifier resin component (B3) is preferably 40% by weight or less, and more preferably 20% by weight or less, of the content of the non-aromatic low-hydroxyl value tackifier resin component (B1).

[0033] Examples of the aromatic low-hydroxyl value tackifying resin component (B3) include aromatic petroleum resins, aliphatic aromatic copolymer petroleum resins, alicyclic aromatic copolymer petroleum resins, styrene-based petroleum resins, xylene-based petroleum resins, terpene-phenol copolymer resins, and those mainly composed of copolymers containing two or more of these resins in the monomer composition. Among these aromatic low-hydroxyl value tackifying resin components (B3), those mainly composed of styrene-based petroleum resins are preferably used.

[0034] Examples of the aromatic low-hydroxyl value tackifying resin component (B3) having a hydroxyl value of less than 100 mgKOH / g include Petcol 140 (manufactured by Tosoh Corporation, aromatic petroleum resin, softening point 135°C, hydroxyl value 0 mgKOH / g), Neopolymer 140 (manufactured by ENEOS Corporation, aromatic petroleum resin, softening point 143°C, hydroxyl value 0 mgKOH / g), ENDEX 155 (manufactured by Synthomer, α-methylstyrene / styrene copolymer resin, softening point 153°C, hydroxyl value 0 mgKOH / g), FMR0150 (manufactured by Mitsui Chemicals, S styrene monomer / aromatic monomer copolymer resin, softening point 145°C, hydroxyl value 0mgKOH / g), FTR2140 (Mitsui Chemicals, Inc., α-methylstyrene / styrene copolymer resin, softening point 137°C, hydroxyl value 0mgKOH / g), FTR2120 (Mitsui Chemicals, Inc., α-methylstyrene / styrene copolymer resin, softening point 125°C, hydroxyl value 0mgKOH / g), Arcon M-135 (Arakawa Chemical Industries, Ltd., partially hydrogenated aromatic petroleum resin, softening point 135°C, hydroxyl value 0mgKOH / g), T-REZ HB125 (manufactured by ENEOS Corporation, hydrogenated dicyclopentadiene / aromatic copolymer petroleum resin, softening point 125°C, hydroxyl value 0mgKOH / g), YS Resin TO125 (manufactured by Yasuhara Chemical Co., Ltd., aromatic modified terpene resin, softening point 125°C, hydroxyl value 0mgKOH / g), YS Polystar U130 (manufactured by Yasuhara Chemical Co., Ltd., terpene phenol resin, softening point 130°C, hydroxyl value 20mgKOH / g), YS Polystar T130 (manufactured by Yasuhara Chemical Co., Ltd., terpene phenol resin, softening point 130°C, hydroxyl value 60mgKOH / g), Sylvares TP2019 (manufactured by Kraton, terpene phenol resin, softening point 125°C, hydroxyl value 80 mgKOH / g), but is not limited thereto. Such aromatic low-hydroxyl value tackifying resin components (B3) having a hydroxyl value of less than 100 mgKOH / g can be used as needed within a range that does not impair the required performance, and two or more types may be used in combination.

[0035] <Non-aromatic liquid plasticizer component (C)> In the hot melt pressure-sensitive adhesive composition of the present invention, by using the non-aromatic liquid plasticizer component (C), it is possible to impart appropriate adhesive strength and good applicability.

[0036] The non-aromatic liquid plasticizer component (C) is preferably, for example, a mineral oil or synthetic oil having a pour point of −10° C. or lower. By making the non-aromatic liquid plasticizer component (C) of such material and characteristics, it is possible to impart appropriate adhesive strength and good application properties to the hot-melt pressure-sensitive adhesive composition. However, the non-aromatic liquid plasticizer component (C) may be a material other than a mineral oil or a synthetic oil, and may have a pour point higher than −10° C., as long as it can impart appropriate adhesive strength and good application properties to the hot-melt pressure-sensitive adhesive composition.

[0037] The non-aromatic liquid plasticizer component (C) preferably does not contain an aromatic component in its composition. If the liquid plasticizer component contains an aromatic component, it will inhibit the physical crosslinking of the aromatic vinyl monomer polymer block of the thermoplastic block copolymer component (A), which is a copolymer of a vinyl aromatic hydrocarbon and a conjugated diene compound in the hot-melt pressure-sensitive adhesive composition, reducing cohesive strength and impairing heat resistance and adhesiveness. Therefore, it is better not to use a liquid plasticizer component containing an aromatic component in applications where heat resistance and adhesiveness are desired.

[0038] In the present invention, the content of the non-aromatic liquid plasticizer component (C) is 5 to 30 parts by weight per 100 parts by weight of the thermoplastic block copolymer component (A), which is a copolymer of a vinyl-based aromatic hydrocarbon and a conjugated diene compound. Increasing the amount of liquid plasticizer increases the flexibility of the hot-melt pressure-sensitive adhesive composition, but decreases the softening point, resulting in poor heat resistance and adhesive strength in high-temperature environments. On the other hand, decreasing the amount of liquid plasticizer increases the softening point and improves high-temperature properties, but increases the melt viscosity, impairing applicability. By adjusting the amount of liquid plasticizer to the above range, it is easy to achieve a good balance of heat resistance, adhesiveness, and applicability. From the above perspectives, the content of the non-aromatic liquid plasticizer component (C) is more preferably 5 to 20 parts by weight per 100 parts by weight of the thermoplastic block copolymer component (A), which is a copolymer of a vinyl-based aromatic hydrocarbon and a conjugated diene compound.

[0039] The non-aromatic liquid plasticizer component (C) is not particularly limited as long as it is a liquid plasticizer that does not contain an aromatic component, and examples thereof include YUBASE2 (manufactured by SK Lubricants, paraffin-based), YUBASE3 (manufactured by SK Lubricants, paraffin-based), YUBASE4 (manufactured by SK Lubricants, paraffin-based), YUBASE6 (manufactured by SK Lubricants, paraffin-based), YUBASE8 (manufactured by SK Lubricants, paraffin-based), Examples of suitable non-aromatic liquid plasticizer components include Diana Process Oil PW-32 (manufactured by Idemitsu Kosan Co., Ltd., paraffin-based), Diana Process Oil PW-90 (manufactured by Idemitsu Kosan Co., Ltd., paraffin-based), Diana Process Oil PW-380 (manufactured by Idemitsu Kosan Co., Ltd., paraffin-based), Polybutene 200N (manufactured by NOF Corporation, polybutene-based), Polybutene 30N (manufactured by NOF Corporation, polybutene-based), Polybutene 10N (manufactured by NOF Corporation, polybutene-based), Polybutene 0N (manufactured by NOF Corporation, polybutene-based), and NISSO-PB B-1000 (manufactured by Nippon Soda Co., Ltd., polybutadiene-based), but are not limited to these. Such non-aromatic liquid plasticizer components can be used as needed to the extent that the required performance is not impaired, and two or more types may be used in combination.

[0040] <Antioxidant ingredient (D)> In the present invention, an antioxidant component (D) can be used as needed. The antioxidant component (D) is used for the purpose of improving the heat stability of the hot-melt pressure-sensitive adhesive composition, for example, by preventing a decrease in molecular weight, gelation, coloration, etc., due to heat. The terms "oxidative deterioration inhibitor," "thermal deterioration inhibitor," and "aging inhibitor" are synonyms for "antioxidant."

[0041] In the present invention, the antioxidant component (D) is preferably contained in an amount of 0.1 to 10 parts by weight per 100 parts by weight of the thermoplastic block copolymer component (A). At less than 0.1 part by weight, it is difficult to obtain the desired thermal stability effect, and adding 10 parts by weight or more does not provide any further improvement in thermal stability. From this perspective, the antioxidant component (D) is more preferably contained in an amount of 1 to 8 parts by weight, and most preferably contained in an amount of 2 to 6 parts by weight, per 100 parts by weight of the thermoplastic block copolymer component (A).

[0042] Examples of the antioxidant component (D) include phenolic antioxidants, thioether antioxidants, and phosphorus-based antioxidants. Examples include ADK STAB AO-50 (manufactured by ADEKA Corporation, phenolic antioxidant), ADK STAB AO-60 (manufactured by ADEKA Corporation, phenolic antioxidant), Irganox 1010 (manufactured by BASF Corporation, phenolic antioxidant), RIANOX 1010 (manufactured by Rianlon Corporation, phenolic antioxidant), Irgafos 168 (manufactured by BASF Corporation, phosphorus-based antioxidant), ADK STAB HP-10 (manufactured by ADEKA Corporation, phosphorus-based antioxidant), ADK STAB AO-412S (manufactured by ADEKA Corporation, thioether-based antioxidant), and Sumilizer TPS (manufactured by Sumitomo Chemical Co., Ltd., thioether-based antioxidant). However, the antioxidant component (D) is not limited to these, and such antioxidants can be used as needed within a range that does not impair the required performance, and two or more types may be used in combination. In particular, a combination of a phenolic antioxidant and a phosphoric acid antioxidant is preferably used.

[0043] <Metal deactivator component (E)> In the present invention, a metal deactivator component (E) can be used as needed. The metal deactivator component (E) is used for the purpose of improving the heat stability of the hot-melt pressure-sensitive adhesive composition by converting metals dissolved from heated production equipment, coating equipment, and adherends into inactive metal compounds, thereby suppressing indirect oxidative degradation and preventing gelation, coloration, etc.

[0044] In the present invention, the metal deactivator component (E) is preferably contained in an amount of 10 parts by weight or less per 100 parts by weight of the thermoplastic block copolymer component (A). Adding more than 10 parts by weight does not provide any further improvement in heat stability. From this perspective, the metal deactivator component is more preferably contained in an amount of 2 to 5 parts by weight per 100 parts by weight of the thermoplastic block copolymer component (A).

[0045] Examples of the metal deactivator component (E) include triazole-based metal deactivators, hydrazide-based metal deactivators, and phosphate-based metal deactivators. Examples include ADK STAB CDA-6S (manufactured by ADEKA Corporation, hydrazide-based metal deactivator), ADK STAB CDA-10 (manufactured by ADEKA Corporation, hydrazide-based metal deactivator), HOSTANOX OSP1 (manufactured by Clariant, phosphate-based metal deactivator), Irganox MD1024 (manufactured by BASF, hydrazide-based metal deactivator), and Naugard XL-1 (manufactured by Addivant, hydrazide-based metal deactivator). However, the metal deactivator component (E) is not limited to these, and any metal deactivator component may be used as needed within a range that does not impair the required performance, and two or more types may be used in combination.

[0046] <Characteristics of hot melt pressure sensitive adhesive composition> The hot-melt pressure-sensitive adhesive composition of the present invention has excellent adhesive properties, specifically, an average 180° peel adhesion strength of the hot-melt pressure-sensitive adhesive composition at 23°C and 60°C of 25 N / 25 mm or more.

[0047] The hot-melt pressure-sensitive adhesive composition of the present invention has excellent heat resistance. Specifically, the heat resistance retention strength of the hot-melt pressure-sensitive adhesive composition is such that, after 8 hours in an 80°C atmosphere under a load of 500 g, the displacement of a test specimen from the initial application position is 3 mm or less.

[0048] The hot-melt pressure-sensitive adhesive composition of the present invention has excellent applicability. Generally, if the melt viscosity of a hot-melt pressure-sensitive adhesive composition is too high, it cannot be discharged from a coating device such as an applicator, or the amount discharged per hour may be significantly low. From this perspective, the melt viscosity of the hot-melt pressure-sensitive adhesive composition at 200°C is 150 Pa·s or less, preferably 100 Pa·s or less.

[0049] These properties of the hot melt pressure sensitive adhesive composition of the present invention are measured by the methods described in the Examples section below.

[0050] <Application> The hot melt pressure-sensitive adhesive composition of the present invention has excellent heat resistance, adhesive properties, and applicability, and can therefore be suitably used in applications such as electrical appliances, communication devices, automobile parts, construction and civil engineering parts, etc. For example, it can be suitably used for bonding components in which one or both of the adherends to be bonded are made of metals such as stainless steel and aluminum, glass, and plastics such as nylon and polycarbonate, and which are exposed to high-temperature environments of 40°C or higher, for example, 40 to 60°C, during use, such as bonding the display and housing of an electrical appliance or bonding internal parts of a smartphone. [Example]

[0051] The present invention will be described below based on examples, but these examples are merely one embodiment of the present invention and the present invention is not limited by these examples. The preparation of test specimens in the examples and comparative examples and the evaluation of the physical properties of the hot-melt pressure-sensitive adhesive compositions were carried out according to the following methods.

[0052] <180° peel adhesive strength> (Test Method) A hot-melt pressure-sensitive adhesive composition was sandwiched between a release liner (manufactured by Mitsui Chemicals Tocello, Inc., product name "SP-PET-O1-50BU") and a PET film (manufactured by Toray Industries, Inc., product name "Lumirror #38-T60") and heat-pressed to obtain a pressure-sensitive adhesive sheet with a 100 μm thick pressure-sensitive adhesive layer. This pressure-sensitive adhesive sheet was cut to a size of 25 mm wide and 100 mm long to prepare test specimens. The release liner covering the test specimen was peeled off in an environment of 23°C and 50% RH, and the specimen was pressed onto a stainless steel (SUS304) plate with a 25 mm wide and 25 mm long adhesive area by rolling a 2 kg roller back and forth once. The specimen was then left overnight in the same environment. The 180° peel adhesion strength (N / 25 mm width) was then measured using a tensile tester in accordance with JIS Z 0237 at a pulling rate of 300 mm / min. Measurements were performed using three test pieces for each PSA sheet (i.e., n=3), and the arithmetic mean values of the 180° peel adhesive strengths for these test pieces are shown in the "180° peel adhesive strength" column in Table 1. The 180° peel adhesive strength at 23°C and 60°C is preferably 25 N / 25 mm or more, and more preferably 30 N / 25 mm or more.

[0053] <Heat-resistance holding power> (Test Method) A hot-melt pressure-sensitive adhesive composition was sandwiched between a release liner (manufactured by Mitsui Chemicals Tocello, Inc., product name "SP-PET-O1-50BU") and a PET film (manufactured by Toray Industries, Inc., product name "Lumirror #38-T60") and heat-pressed to obtain a pressure-sensitive adhesive sheet with a 100 μm thick pressure-sensitive adhesive layer. This pressure-sensitive adhesive sheet was cut to a size of 25 mm wide and 100 mm long to prepare a test specimen. The release liner covering the test specimen was peeled off in an environment of 23°C and 50% RH, and the specimen was heat-sealed (150°C, 5 seconds, 3 kgf / cm²) to a stainless steel (SUS304) plate over an application area of 25 mm wide and 25 mm long, and then left to stand overnight in the same environment. One end of the test piece thus attached to the adherend was fixed, the adherend was hung so that the length direction of the test piece was vertical, a 500 g load was applied to the free end of the test piece, and in accordance with JIS Z 0237, the test piece was left in an 80°C environment with this load applied for 8 hours. After this time, the test piece was measured for the distance it had shifted from its initial attachment position (displacement distance). Measurements were performed using three test pieces for each pressure-sensitive adhesive sheet (i.e., n = 3), and the arithmetic mean value of the displacement distances for these test pieces is shown in the "Heat Resistance Holding Power" column in Table 1. It is preferable that the displacement distance after 8 hours be 3 mm or less.

[0054] <Melt viscosity> (Measurement method) The hot-melt pressure-sensitive adhesive composition was heated to melt, and the viscosity of the molten state was measured at 200°C using a Brookfield RVT viscometer (spindle No. 27) in accordance with JIS K 6862. From the viewpoint of coating workability, the melt viscosity at 200°C is preferably 150 Pa s or less, and more preferably 100 Pa s or less.

[0055] The present invention will be specifically described below with reference to examples and comparative examples, but the present invention is not limited to these examples.

[0056] Examples 1 to 8 and Comparative Examples 1 to 8 The components (A to E) shown in Table 1 were mixed and melt-kneaded in a double-arm kneader at about 180°C for about 1 hour to prepare the hot-melt pressure-sensitive adhesive compositions of Examples 1 to 8 and Comparative Examples 1 to 8.

[0057] The components in Tables 1 and 2 are as follows: [(A): Block copolymer component represented by A-B-A type] (A-1): Quintac 3280 (manufactured by Zeon Corporation, styrene content 25%, diblock content 17%, weight average molecular weight 135,000, linear structure) (A-2): Quintac 3190 (manufactured by Zeon Corporation, styrene content 30%, diblock content 60%, weight average molecular weight 125,000, asymmetric linear structure) (A-3): Kraton D1164 (manufactured by Kraton, styrene content 29%, diblock content 0%, weight average molecular weight 120,000, linear structure) (A-4): Quintac 3270 (manufactured by Zeon Corporation, styrene content 24%, diblock content 67%, weight average molecular weight 135,000 linear structure) (A-5): Quintac 3450 (manufactured by Zeon Corporation, styrene content 19%, diblock content 30%, weight average molecular weight 195,000 radial structure)

[0058] [(B): Tackifying resin component] (B1) Non-aromatic low hydroxyl value tackifying resin component (B1-1): Alcon P-125 (Arakawa Chemical Industries, fully hydrogenated aromatic petroleum resin, softening point 125°C, hydroxyl value 0mgKOH / g) (B1-2): YS Resin PX1250 (Yasuhara Chemical Co., Ltd., terpene resin, softening point 125°C, hydroxyl value 0 mgKOH / g) (B1-3) Alcon P-140 (Arakawa Chemical Industries, fully hydrogenated aromatic petroleum resin, softening point 140°C, hydroxyl value 0mgKOH / g) (B1-4): Alcon P-100 (Arakawa Chemical Industries, fully hydrogenated aromatic petroleum resin, softening point 100°C, hydroxyl value 0mgKOH / g) (B2) High hydroxyl value tackifying resin component (B2-1): YS Polyster N125 (Yasuhara Chemical Co., Ltd., terpene phenol resin, softening point 125°C, hydroxyl value 160 mgKOH / g) (B2-2): YS Polyster S145 (Yasuhara Chemical Co., Ltd., terpene phenol resin, softening point 145°C, hydroxyl value 100 mgKOH / g) (B3) Aromatic low hydroxyl value tackifying resin component (B3-1): FTR2120 (Mitsui Chemicals, Inc., α-methylstyrene / styrene copolymer resin, softening point 120°C, hydroxyl value 0 mgKOH / g) (B3-2): YS Polyster T130 (Yasuhara Chemical Co., Ltd., terpene phenol resin, softening point 130±5°C, hydroxyl value 60 mgKOH / g)

[0059] [(C): Non-aromatic liquid plasticizer component] (C-1): Diana Process Oil PW-380 (manufactured by Idemitsu Kosan, paraffin-based, aromatic-free) (C-2): Polybutene 30N (NOF Corporation, polybutene type, aromatic-free) (C-3): Diana Process Oil NS-100 (manufactured by Idemitsu Kosan, naphthenic, containing aromatic components)

[0060] [(D): Antioxidant component] (D-1) Irganox 1010 (BASF, phenolic antioxidant) (D-2) Irgafos 168 (BASF, phosphoric acid antioxidant)

[0061] [(E): Metal deactivator component] (E) ADK STAB CDA-10 (ADEKA Corporation, hydrazide-based metal deactivator)

[0062] [Table 1]

[0063] [Table 2]

[0064] As is clear from the results in Table 1, it was confirmed that the hot melt pressure sensitive adhesive compositions of the present invention of Examples 1 to 8 were excellent in heat resistance and adhesiveness, as well as in applicability.

[0065] Comparative Example 1 exhibits poor adhesion because it does not contain the non-aromatic low-hydroxyl value tackifying resin component (B1) with a hydroxyl value of less than 100 mgKOH / g. Comparative Example 2 exhibits poor adhesion and heat resistance at 60°C because it does not contain the high-hydroxyl value tackifying resin component (B2) with a hydroxyl value of 100 mgKOH / g or more and contains an excessive amount of the non-aromatic low-hydroxyl value tackifying resin component (B1) with a hydroxyl value of less than 100 mgKOH / g. Comparative Example 3 exhibits high solution viscosity and poor application suitability because it does not contain the non-aromatic liquid plasticizer component (C). Comparative Example 4 exhibits poor adhesion and heat resistance at 60°C because the diblock content of the A-B-A type thermoplastic block copolymer component (A) is high. Comparative Example 5 exhibits poor heat resistance because the styrene content of the A-B-A type thermoplastic block copolymer component (A) is low. Comparative Example 6 had poor heat resistance due to the low softening point of the non-aromatic low-hydroxyl value tackifying resin component (B1) with a hydroxyl value of less than 100 mgKOH / g, and Comparative Example 7 had poor adhesion at 60°C due to the hydroxyl value of less than 100 mgKOH / g (B3-2), although it contained hydroxyl groups. Comparative Example 8 had poor heat resistance due to the liquid plasticizer component (C) containing an aromatic component.

Claims

1. The hot melt pressure-sensitive adhesive composition contains 100 parts by weight of a thermoplastic block copolymer component (A), which is a copolymer of a vinyl-based aromatic hydrocarbon and a conjugated diene compound, 50 to 110 parts by weight of a tackifier resin component (B) having a softening point of 120°C to 160°C, and 5 to 30 parts by weight of a non-aromatic liquid plasticizer component (C). The thermoplastic block copolymer component (A) contains 20% by weight or more of a vinyl-based aromatic hydrocarbon component and has a diblock content of 60% by weight or less. The tackifier resin component (B) contains 10 to 90% by weight of a non-aromatic low-hydroxyl value tackifier resin component (B1) having a hydroxyl value of less than 100 mgKOH / g and 90 to 10% by weight of a high-hydroxyl value tackifier resin component (B2) having a hydroxyl value of 100 mgKOH / g or more.

2. 2. The hot melt pressure-sensitive adhesive composition according to claim 1, wherein the vinyl aromatic hydrocarbon of the thermoplastic block copolymer component (A) is styrene.

3. 3. The hot melt pressure-sensitive adhesive composition according to claim 1, wherein the conjugated diene compound of the thermoplastic block copolymer component (A) is isoprene.

4. 3. The hot melt pressure-sensitive adhesive composition according to claim 1, wherein the thermoplastic block copolymer component (A) has a weight average molecular weight of 200,000 or less.

5. 3. The hot melt pressure-sensitive adhesive composition according to claim 1, wherein the high hydroxyl value tackifying resin component (B2) is a phenol-modified tackifying resin.

6. 3. The hot melt pressure-sensitive adhesive composition according to claim 1, wherein the non-aromatic liquid plasticizer component (C) is a mineral oil or a synthetic oil having a pour point of −10° C. or lower.

7. 3. The hot melt pressure-sensitive adhesive composition according to claim 1, which has a 180° peel adhesion strength of 25 N / 25 mm or more at 23°C and 60°C.

8. 3. The hot melt pressure-sensitive adhesive composition according to claim 1, which is used in electrical appliances, communication devices, automobile parts, and construction and civil engineering parts.

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