Hot melt adhesive composition, adhesive tape, and article

Abstract

Provided are: a hot-melt adhesive composition which contains a large amount of plant-derived components, has excellent adhesive properties, in particular, 180 DEG peel adhesion, constant load retention, and shear retention, and also has high re-peelability; and an adhesive tape which has an adhesive layer that contains the adhesive composition. The hot melt adhesive composition contains at least (A) a styrene block copolymer having a farnesene structure, (B) a thermoplastic resin having a kinematic viscosity (40 DEG C) of 150 mm2 / s to 200 thousand mm2 / s or a number average molecular weight (Mn) of 450 to 4000, and (C) a tackifier resin having a softening point of 100 DEG C or more. The tackifying resin (C) is contained in an amount of 30 to 500 parts by mass per 100 parts by mass of the styrene block copolymer (A).

Description

Technical Field

[0001] This invention relates to hot melt adhesive compositions, and more specifically, to hot melt adhesive compositions containing styrene-based block copolymers having a farnesene structure, and to adhesive tapes having an adhesive layer comprising the adhesive composition. Background Technology

[0002] Because hot melt adhesives are solvent-free, they reduce the environmental impact during manufacturing and are therefore widely used to fix components of larger electronic devices such as thin-film televisions, home appliances, and OA equipment (office automation equipment), as well as smaller electronic devices such as portable electronic terminals, cameras, and personal computers. Furthermore, as a solution that can be manufactured with a lower environmental impact than petroleum-derived components, hot melt adhesives containing plant-derived components have been proposed (see, for example, Patent Documents 1 and 2).

[0003] Furthermore, from the perspective of protecting the Earth's environment and for the purpose of saving resources, there is an increasing trend of reusing or recycling the components used in used products by breaking them down. In this case, when adhesive tape is used, it is necessary to peel the adhesive tape attached to the components. Therefore, there is a demand for adhesive tape with excellent re-peelability that can be peeled and removed without leaving adhesive residue on the components.

[0004] Furthermore, for adhesive tapes used to fix components, it is important that they can fix components without peeling during use, so it is desirable that they all have good 180° peel adhesion, constant load holding force and shear holding force.

[0005] Existing technical documents Patent documents Patent Document 1: Japanese Patent Application Publication No. 2014-237257 Patent Document 2: Japanese Patent Application Publication No. 2023-162607 Summary of the Invention

[0006] The technical problem that the invention aims to solve Patent Document 1 describes a laminate with high interlayer adhesion and minimal softener exudation even when softener is present. Patent Document 2 describes a hot melt composition with high operability, excellent initial adhesion when bonded to the substrate, and high peel strength, resulting in high adhesion and significantly reduced grease exudation. However, neither of these patents addresses the re-peelability when peeling the adhesive tape attached to the component, nor does it consider the balance between the 180° peel adhesion, constant load holding force, and shear holding force required for the adhesive tape used to fix the component and re-peelability.

[0007] Therefore, the technical problem to be solved by the present invention is to provide a hot melt adhesive composition and an adhesive tape having an adhesive layer containing the adhesive composition. Compared with conventional hot melt adhesive compositions containing petroleum-derived components, the hot melt adhesive composition contains more plant-derived components and has excellent 180° peel adhesion, constant load holding force and shear holding force, and also has high re-peelability.

[0008] Technical solutions for solving technical problems The present invention includes the following methods.

[0009] [1] A hot-melt adhesive composition comprising at least a styrene-based block copolymer (A) having a farnesene structure, a thermoplastic resin (B), and a tackifying resin (C), wherein the thermoplastic resin (B) has a kinematic viscosity (40°C) of 150 mm. 2 / s or higher and 200,000 mm 2 The tackifying resin (C) has a softening point of 100°C or higher, and contains 30 to 500 parts by weight of the tackifying resin (C) relative to 100 parts by weight of the styrene block copolymer (A). The number average molecular weight (Mn) is 450 or higher and 4000 or lower.

[0010] [2] According to the hot melt adhesive composition described in [1] above, wherein the styrene-based block copolymer (A) comprises a polymer block (A-1) containing structural units derived from styrene and a polymer block (A-2) containing structural units derived from farnesene.

[0011] [3] According to the hot melt adhesive composition described in [1] or [2] above, wherein the kinematic viscosity (40°C) of the thermoplastic resin (B) is 20,000 mm³. 2 / s or higher and 200,000 mm 2 / s or a number-average molecular weight (Mn) of 1000 or more but less than 4000.

[0012] [4] The hot melt adhesive composition according to any one of [1] to [3] above, wherein the weight average molecular weight (Mw) of the styrene block copolymer (A) is 10,000 to 500,000.

[0013] [5] The hot melt adhesive composition according to any one of [2] to [4] above, wherein the content of the polymer block (A-1) in the total amount of the styrene block copolymer (A) is 35% by mass or less.

[0014] [6] The hot melt adhesive composition according to any one of [1] to [5] above, wherein, relative to 100 parts by weight of the styrene block copolymer (A), it contains 5 to 300 parts by weight of the thermoplastic resin (B).

[0015] [7] The hot melt adhesive composition according to any one of [1] to [6] above, wherein the thermoplastic resin (B) is liquid at 23°C.

[0016] [8] The hot melt adhesive composition according to any one of [1] to [7] above, wherein the thermoplastic resin (B) contains an olefin resin.

[0017] [9] The hot melt adhesive composition according to any one of [1] to [8] above, wherein the haze of the adhesive layer with a thickness of 40 μm obtained from the hot melt adhesive composition is less than 10%.

[0018]

[10] The hot melt adhesive composition according to any one of [1] to [9] above, wherein the storage modulus G' of the hot melt adhesive composition at 180°C is 5 × 10⁻⁶. 3 the following.

[0019]

[11] The hot melt adhesive composition according to any one of [1] to

[10] above, wherein the biomass content of the hot melt adhesive composition is 30% or more.

[0020]

[12] The hot melt adhesive composition according to any one of [1] to

[11] above, wherein the hot melt adhesive composition contains one or more selected from anti-aging agents, ultraviolet absorbers, heat stabilizers and resin reinforcing agents.

[0021]

[13] An adhesive tape comprising an adhesive layer comprising any one of the hot melt adhesive compositions described in any one of [1] to

[12] above.

[0022]

[14] An article that uses the adhesive tape described above

[13] .

[0023] Invention Effects According to the present invention, a hot melt adhesive composition and an adhesive tape having an adhesive layer comprising the adhesive composition are provided, wherein the hot melt adhesive composition contains a large amount of plant-derived components and has excellent adhesive properties, particularly 180° peel strength, constant load holding force and shear holding force, and also has high re-peelability. Attached Figure Description

[0024] Figure 1 This is a conceptual diagram representing the method for measuring shear holding force.

[0025] Figure 2 This is a conceptual diagram representing a method for measuring the holding force under constant load. Detailed Implementation

[0026] The hot-melt adhesive composition of the present invention contains at least a styrene-based block copolymer (A) having a farnesene structure, a thermoplastic resin (B), and a tackifying resin (C), wherein the thermoplastic resin (B) has a kinematic viscosity (40°C) of 150 mm. 2 / s or higher and 200,000 mm 2 The tackifying resin (C) has a softening point of 100°C or higher, and contains 30 to 500 parts by weight of the tackifying resin (C) relative to 100 parts by weight of the styrene block copolymer (A). The number average molecular weight (Mn) is 450 or higher and 4000 or lower.

[0027] The hot melt adhesive composition of the present invention, by having the above-mentioned characteristics, contains a large number of plant-derived ingredients, and exhibits excellent 180° peel strength, constant load holding force and shear holding force, as well as excellent re-peelability.

[0028] The hot melt adhesive composition of the present invention will now be described in more detail based on its constituent elements.

[0029] <Hot Melt Adhesive Composition> (A) A styrene-based block copolymer with a farnesene structure The styrene-based block copolymer (A) having a farnesene structure in this invention (hereinafter, sometimes referred to as styrene-based block copolymer (A)) preferably comprises a polymer block (A-1) containing a structural unit derived from styrene and a polymer block (A-2) containing a structural unit derived from farnesene.

[0030] In the present invention, the styrene-based block copolymer (A) having a farnesene structure, when comprising a polymer block (A-1) containing a structural unit derived from styrene and a polymer block (A-2) containing a structural unit derived from farnesene, can be a diblock copolymer comprising one polymer block (A-1) and one polymer block (A-2), a triblock copolymer comprising two polymer blocks (A-1) and one polymer block (A-2), or a multiblock copolymer comprising a total of four or more polymer blocks (A-1) and polymer blocks (A-2). Furthermore, the above-mentioned styrene-based block copolymer (A) can be used in only one form or in two or more forms. Triblock copolymers, in particular, exhibit a good balance between viscosity and elasticity, readily demonstrating good adhesive properties, and are therefore especially preferred.

[0031] (Polymer Block (A-1)) Examples of styrene-based compounds constituting the styrene-derived structural units in the polymer block (A-1) include styrene, α-methylstyrene, 2-methylstyrene, 3-methylstyrene, 4-methylstyrene, 4-propylstyrene, 4-tert-butylstyrene, 4-cyclohexylstyrene, 4-dodecylstyrene, 2,4-dimethylstyrene, 2,4-diisopropylstyrene, 2,4,6-trimethylstyrene, 2-ethyl-4-benzylstyrene, 4-(phenylbutyl)styrene, 4-methoxystyrene, monochlorostyrene, and dichlorostyrene. These styrene-based compounds may be used alone or in combination of two or more.

[0032] The content of the polymer block (A-1) containing styrene-derived structural units in the total amount of the aforementioned styrene-based block copolymer (A) is preferably 35% by mass or less, more preferably 10 to 30% by mass, and even more preferably 15 to 25% by mass. Since the polymer block (A-1) containing styrene-derived structural units acts as a physical pseudo-crosslinking point, when the content is within the above range, it can achieve a good balance of shear retention under heating, high cohesiveness required for recycling, tackiness during adhesion, and moderate tackiness required for hot melt coating adaptability.

[0033] (Polymer Block (A-2)) The polymer block (A-2) mentioned above may contain only structural units (i) derived from farnesene, or it may contain structural units (ii) derived from conjugated dienes other than farnesene, in addition to structural units derived from farnesene.

[0034] Farnesene can be used in structural units (i) derived from farnesene.

[0035] Examples of diene compounds that constitute structural units (ii) derived from conjugated dienes other than farnesene include isoprene, butadiene, 2,3-dimethyl-butadiene, 2-phenyl-butadiene, 1,3-pentadiene, 2-methyl-1,3-pentadiene, 1,3-hexadiene, 1,3-octadiene, 1,3-cyclohexadiene, 2-methyl-1,3-octadiene, 1,3,7-octtriene, myrcene, and chloroprene. They can be used alone or in combination of two or more.

[0036] More preferably, at least one of isoprene, butadiene, and myrcene is selected, and even more preferably, at least one of butadiene and isoprene is selected.

[0037] The content of the structural unit (i) derived from farnesene in the total amount of the above polymer block (A-2) is 1 to 100% by mass, preferably 60 to 100% by mass, more preferably 70 to 100% by mass, even more preferably 75 to 100% by mass, further preferably 90 to 100% by mass, and even more preferably 95 to 100% by mass.

[0038] In addition, the content of structural units (ii) derived from conjugated dienes other than farnesene in the total amount of the above polymer block (A-2) is 0 to 99% by mass, preferably 0 to 40% by mass, more preferably 0 to 30% by mass, more preferably 0 to 25% by mass, even more preferably 0 to 10% by mass, and even more preferably 0 to 5% by mass.

[0039] The content of polymer block (A-2) in the total amount of the above-mentioned styrene-based block copolymer (A) is preferably 50% by mass or more, more preferably 60 to 90% by mass, and even more preferably 70 to 85% by mass. The polymer block (A-2) helps to impart softness to the adhesive composition and adjust the cohesive force to achieve a balance as an adhesive composition. Therefore, when the content is within the above range, it is possible to achieve a good balance of shear retention under heating, high cohesive force required for recycling, tackiness during application, and moderate tackiness required for hot melt coating.

[0040] The glass transition temperature (Tg) of the styrene-based block copolymer (A) is preferably below 0°C, more preferably -80 to -20°C, and even more preferably -70 to -30°C. When the glass transition temperature (Tg) is within this range, the polymer block (A-1) functions as a hard segment, acting as a physical pseudo-crosslinking point, and exhibits excellent shear retention, re-peelability, and hot-melt coating adaptability when used in hot-melt adhesive compositions. Furthermore, the polymer block (A-2) functions as a soft segment with excellent flexibility, exhibiting excellent low-temperature properties and impact resistance when used in hot-melt adhesive compositions.

[0041] The glass transition temperature of the styrene block copolymer (A) was determined by extrapolation from the curve obtained by analyzing the styrene block copolymer (A) using differential scanning calorimetry (DSC).

[0042] The weight-average molecular weight of the styrene-based block copolymer (A) is preferably 10,000 to 500,000, more preferably 20,000 to 400,000, even more preferably 50,000 to 300,000, particularly preferably 50,000 to 200,000, and most preferably 100,000 to 150,000. When the weight-average molecular weight of the styrene-based block copolymer (A) is within the above range, the adhesive properties of the hot melt adhesive composition, such as adhesion, cohesion, and tackiness, become good, and it can have flowability suitable for melt molding.

[0043] The molecular weight distribution (weight average molecular weight / number average molecular weight) of the styrene-based block copolymer (A) is preferably in the range of 1.0 to 2.0, more preferably in the range of 1.0 to 1.7, and even more preferably in the range of 1.0 to 1.5. By ensuring that the molecular weight distribution of the styrene-based block copolymer (A) is within the above range, when mixed with the thermoplastic resin (B) described later within the specified range, it exhibits excellent shear retention and re-peelability.

[0044] It should be noted that the weight-average molecular weight and number-average molecular weight used in this invention refer to values ​​calculated by gel permeation chromatography (GPC) and conversion to standard polystyrene. Specifically, a GPC apparatus (HLC-8320 GPC) manufactured by Tosoh Corporation can be used for the determination under the following conditions.

[0045] • Sample concentration: 0.5% by mass (tetrahydrofuran solution) • Sample injection volume: 100 μl • Eluent: Tetrahydrofuran • Flow rate: 1.0 ml / min • Measurement temperature: 40℃ ·This column: 1 piece of TSKgelG5000HXL + 1 piece of TSKgelG4000HXL + 1 piece of TSKgelG3000HXL + 2 pieces of TSKgelG2500HXL • Protective pillar: TSKgel HXL-H • Detector: Differential refractometer • Weight average molecular weight of standard polystyrene: 5 million to 5 million (manufactured by Tosoh Corporation) The styrene-based block copolymer (A) described above can be synthesized by polymerizing the raw material monomers, or commercially available products can be used. There are no particular limitations on the polymerization method; for example, anionic polymerization, atom transfer radical polymerization (ATRP), etc., can be used. Detailed descriptions of each polymerization method are omitted here. For anionic polymerization, known methods such as using an organoalkali metal compound as a polymerization initiator in the presence of inorganic acid salts such as alkali metal or alkaline earth metal salts, using an organoalkali metal compound as a polymerization initiator in the presence of organoaluminum compounds, and using an organorare earth metal complex as a polymerization initiator can be used. For ATRP, known methods such as using an organohalide or sulfonyl halide compound as an initiator in the presence of transition metal compounds or nitrogen-containing compounds can be used. Commercially available products include, for example: Septon SF902 (product name, manufactured by Kuraray, styrene content: 18% by weight), Septon SF903 (product name, manufactured by Kuraray, styrene content: 30% by weight), Septon SF904 (product name, manufactured by Kuraray, styrene content: 21% by weight), etc.

[0046] The aforementioned styrene-based block copolymer (A) contains structural units (i) derived from farnesene. Farnesene can be industrially manufactured using microorganisms, using sugar extracted from plants such as sugarcane as a raw material. Because the hot-melt adhesive composition of the present invention uses farnesene as a raw material, it has a high biomass content and is carbon-neutral upon incineration, thus reducing environmental impact. Farnesene can be classified into α-farnesene and β-farnesene based on its structure. In the present invention, β-farnesene is more preferably used.

[0047] Biomass content refers to the content of plant-derived components. The biomass content of the aforementioned styrene-based block copolymer (A) is preferably 30% or more, more preferably 50% or more, and even more preferably 70% or more. It should be noted that the biomass content in this invention is an indicator measured according to ASTM D6866-16, representing the proportion of biologically derived substances in the target material.

[0048] In the total amount of the hot melt adhesive composition of the present invention, the content of the above-mentioned styrene-based block copolymer (A) is preferably 10 to 80% by mass, more preferably 20 to 60% by mass, and even more preferably 20 to 50% by mass. When the content of the above-mentioned styrene-based block copolymer (A) is within the above range, it moderately exhibits cohesive strength derived from the polymer, especially excellent shear retention and re-peelability.

[0049] (Thermoplastic resin (B)) In addition to the styrene-based block copolymer (A) described above, the hot melt adhesive composition of the present invention also incorporates a thermoplastic resin (B), thereby significantly improving the adaptability of hot melt coating without reducing adhesive strength, constant load holding force, and shear holding force.

[0050] The thermoplastic resin (B) in this invention can be, for example, hydrocarbon oils such as paraffin-based, olefin-based, cycloalkane-based, and aromatic-based oils; vegetable oils such as peanut oil and rosin; phosphate esters; low molecular weight polyethylene glycol; liquid paraffin; hydrocarbon synthetic oils such as low molecular weight polyethylene, ethylene-α-olefin copolymer oligomers, liquid polybutene, liquid polyisoprene or its hydrogenated form, and liquid polybutadiene or its hydrogenated form. One or more of these can be used individually or in combination, as long as the thermoplastic resin as a whole meets the conditions described below, there are no particular limitations.

[0051] The number average molecular weight of the aforementioned thermoplastic resin (B) is more preferably 450 to 4000, further preferably 1000 to 3000, and particularly preferably 1000 to 2000. When the number average molecular weight of the aforementioned thermoplastic resin (B) is within the above range, the adhesive properties of the hot melt adhesive composition, such as adhesion, cohesion, and tack, become good, and exudation during re-peeling can also be suppressed. Furthermore, it can possess flowability suitable for melt molding.

[0052] The kinematic viscosity of the above-mentioned thermoplastic resin (B) at 40°C is 150–200,000 mm³. 2 / s, preferably 1000~200000mm 2 / s, more preferably 20000~200000mm 2 / s, further preferably 20000~100000mm 2 / s. When the kinematic viscosity of the above-mentioned thermoplastic resin (B) at 40°C is within the above-mentioned range, it can exhibit the cohesive force required for shear retention while maintaining good viscosity. It should be noted that the kinematic viscosity of the above-mentioned thermoplastic resin (B) at 40°C generally tends to increase accordingly when the molecular weight of the above-mentioned thermoplastic resin (B) is high.

[0053] The kinematic viscosity of the thermoplastic resin (B) described above in this invention at 40°C was determined by a method according to JIS K2283, specifically by a glass capillary viscometer.

[0054] From the viewpoint of exhibiting good viscosity, the above-mentioned thermoplastic resin (B) is preferably a liquid at room temperature (23°C).

[0055] The content of the thermoplastic resin (B) relative to 100 parts by weight of the styrene-based block copolymer (A) is preferably 5 to 300 parts by weight, more preferably 20 to 250 parts by weight, and even more preferably 30 to 200 parts by weight. When the content of the thermoplastic resin (B) is within the above range, a hot melt adhesive composition with excellent balance between good adhesion, shear retention, and re-peelability can be prepared.

[0056] (Tackifying resin (C)) In addition to the styrene-based block copolymer (A) and thermoplastic resin (B) described above, the hot-melt adhesive composition of the present invention also contains a tackifying resin (C). By containing the tackifying resin (C), the hot-melt adhesive composition of the present invention improves the adhesive strength to a level sufficient for practical use and satisfies properties such as adhesive strength, shear retention, constant load retention, and re-peelability.

[0057] The tackifying resin (C) in this invention preferably has compatibility with styrene-based block copolymers (A) and thermoplastic resins (B). There are no particular limitations on the type of resin with such compatibility; it can be appropriately selected from various known tackifying resins such as petroleum resins, styrene-based resins (except for styrene-based block copolymers (A)), coumarone-indene resins, terpene resins, modified terpene resins, rosin-based resins, rosin derivative resins, and ketone resins.

[0058] Examples of petroleum resins include aliphatic (C5 series) petroleum resins, aromatic (C9 series) petroleum resins, aliphatic / aromatic copolymers (C5 / C9 series) petroleum resins, and their hydrides (e.g., alicyclic petroleum resins obtained by hydrogenating aromatic petroleum resins).

[0059] Examples of styrene-based resins include resins with styrene homopolymer as the main component, resins with α-methylstyrene homopolymer as the main component, resins with vinyltoluene homopolymer as the main component, and resins with copolymers containing two or more of styrene, α-methylstyrene, and vinyltoluene as the main component (e.g., α-methylstyrene / styrene copolymer resin with α-methylstyrene / styrene copolymer as the main component).

[0060] As a coumarone-indene resin, a resin containing coumarone and indene as monomeric components constituting the resin backbone (main chain) can be used. Examples of monomeric components that can be included in the resin backbone other than coumarone and indene include styrene, α-methylstyrene, methylindene, vinyltoluene, etc.

[0061] Examples of terpene resins include α-pinene polymers, β-pinene polymers, and dipentene polymers. Examples of modified terpene resins include resins obtained by modifying the above-mentioned terpene resins (phenol modification, catechol modification, styrene modification, hydrogenation modification, hydrocarbon modification, etc.). Specifically, examples include terpene phenol resins, styrene-modified terpene resins, hydrogenated terpene resins, and terpene catechol resins.

[0062] The term "terpene phenol resin" as used above refers to a polymer containing terpene residues and phenol residues. It encompasses both copolymers of terpenes and phenolic compounds (terpene-phenol copolymer resins) and resins obtained by modifying homopolymers or copolymers of terpenes (terpene resins, typically unmodified terpene resins) with phenol (phenol-modified terpene resins). Preferred examples of terpenes constituting the aforementioned terpene phenol resin include monoterpenes such as α-pinene, β-pinene, and limonene (including d-form, l-form, and d / l-form (dipentene)).

[0063] Specific examples of rosin-based resins include unmodified rosin (gum rosin, wood rosin, tall oil rosin, etc., also known as raw rosin) and modified rosin (rosin obtained by modifying unmodified rosin through hydrogenation, disproportionation, polymerization, other chemical modifications, etc.). In addition, examples of rosin derivative resins include esters of unmodified rosin and esters of modified rosin; unmodified rosin and modified rosin modified with unsaturated fatty acids; unsaturated fatty acid modified rosin esters obtained by modifying rosin esters with unsaturated fatty acids; rosin alcohols obtained by reducing the carboxyl groups in unmodified rosin, modified rosin, unsaturated fatty acid modified rosin, or unsaturated fatty acid modified rosin esters; metal salts of rosin (especially rosin esters), such as unmodified rosin, modified rosin, and various rosin derivatives; and rosin phenolic resins obtained by thermal polymerization of rosin (unmodified rosin, modified rosin, various rosin derivatives, etc.) by adding phenols to rosin using an acid catalyst.

[0064] From the viewpoint of good compatibility with styrene-based block copolymers (A) and thermoplastic resins (B) and improved re-peelability, petroleum resins, rosin-based resins, and terpene resins are preferred. Furthermore, from the viewpoint of increasing the content of plant-derived components and improving biomass quality, terpene resins and rosin-based resins are preferred.

[0065] From the viewpoint of excellent compatibility with styrene-based block copolymers (A) and thermoplastic resins (B), the tackifying resin (C) in this invention is preferably a low-polarity tackifying resin. When the tackifying resin (C) has good compatibility with styrene-based block copolymers (A) and thermoplastic resins (B), the property-improving effect brought about by the formulation of the tackifying resin (C) can be fully obtained, which is therefore preferred. In addition, from the viewpoint of preventing the deterioration of the tackifying resin (C) during the melting process of the hot-melt adhesive composition, a hydrogenated tackifying resin is preferred.

[0066] In the case of the hot melt adhesive composition of the present invention, when the above-mentioned tackifying resin (C) has excellent compatibility with the styrene block copolymer (A) and the thermoplastic resin (B), the haze of the resulting adhesive layer can be suppressed to a low level.

[0067] The haze of the adhesive layer with a thickness of 40 μm obtained from the hot melt adhesive composition is preferably 10% or less, more preferably 8% or less. When the haze of the adhesive layer is within the above range, the tackifying resin (C) is sufficiently compatible with the styrene-based block copolymer (A) and the thermoplastic resin (B), and the property improvement effect brought about by the formulation of the tackifying resin (C) can be fully obtained.

[0068] The haze in this invention is measured using the method described in the examples.

[0069] From the viewpoint of shear retention at high temperatures, the aforementioned tackifying resin (C) contains at least one tackifying resin with a softening point of 100°C or higher. By incorporating such a tackifying resin (C) with a high softening point, in addition to adhesive strength and shear retention, constant load retention and re-peelability can be significantly improved. From the viewpoint of further improving this property, the softening point of the tackifying resin (C) is preferably 100°C or higher, more preferably 110°C or higher.

[0070] In addition, the softening point of the above-mentioned tackifying resin (C) is preferably below 250°C, more preferably below 180°C, even more preferably below 160°C, and most preferably below 150°C.

[0071] When the softening point of the aforementioned tackifying resin (C) is within the above-mentioned range, it is possible to prevent the resin from becoming too hard and obtain suitable tack as an adhesive. Furthermore, it is possible to improve shear retention force and constant load retention force under high-temperature environments. It should be noted that one type of tackifying resin (C) may be used, or two or more types may be used. When two or more types are used, based on the total mass of all tackifying resins, the tackifying resin having the aforementioned suitable softening point is preferably 50% by mass or more, more preferably 60% by mass or more.

[0072] The softening point of the tackifying resin (C) described above in this invention is a value obtained by the ring and ball method based on JISK5902.

[0073] When the styrene-based block copolymer (A) is set at 100 parts by weight, the amount of the tackifying resin (C) is 30 to 500 parts by weight, preferably 30 to 300 parts by weight, more preferably 50 to 200 parts by weight, and even more preferably 75 to 175 parts by weight. When the amount of the tackifying resin (C) is within the above range, the adhesive strength, shear retention force, and constant load retention force can be significantly improved. In particular, the shear retention force and constant load retention force under high temperature environments can be improved.

[0074] (Anti-aging agent) The hot-melt adhesive composition of the present invention may contain an anti-aging agent as needed. By using the anti-aging agent, thermal degradation of the adhesive is prevented, thus improving quality stability. One type of anti-aging agent may be used alone, or two or more may be used in combination. Examples of anti-aging agents include phosphorus-based antioxidants, phenolic antioxidants (such as hindered phenolic antioxidants), hindered amine antioxidants, aromatic amine antioxidants, and sulfur-based antioxidants. While not particularly limited, the amount of anti-aging agent contained in the hot-melt adhesive composition disclosed herein may be 10 parts by weight or less, preferably 7 parts by weight or less, or even 3 parts by weight or less, relative to the total 100 parts by weight of the styrene-based block copolymer (A), thermoplastic resin (B), and tackifying resin (C) having the farnesene structure described above. In addition, relative to the total of 100 parts by weight of the styrene-based block copolymer (A), thermoplastic resin (B), and tackifying resin (C) having the farnesene structure, the amount of the anti-aging agent may be, for example, 0.1 parts by weight or more, 0.5 parts by weight or more, or 1 part by weight or more.

[0075] (Any ingredient) The hot-melt adhesive composition of the present invention may, as needed, contain one or more rubber-like polymers other than styrene-based block copolymers, without significantly impairing the effects of the present invention. The rubber-like polymers are various polymers known in the adhesive field, such as rubber-based, acrylic-based, polyester-based, urethane-based, polyether-based, silicone-based, polyamide-based, and fluorine-based polymers.

[0076] The hot-melt adhesive composition of the present invention contains, as needed, various additives commonly used in the adhesive field, such as leveling agents, crosslinking agents, crosslinking aids, plasticizers, softeners, fillers, colorants (pigments, dyes, etc.), antistatic agents, ultraviolet absorbers, and light stabilizers, without significantly impairing the effects of the present invention. Such additives can be obtained using conventionally known additives.

[0077] The storage modulus G' of the hot melt adhesive composition of the present invention at 180°C is preferably 5 × 10⁻⁶. 3 Pa or less, more preferably 3×10 Pa 3 Pa or less, more preferably 1×10 3 Pa or less, preferably 500 Pa or less. When the storage modulus G' is set within the above range, it is possible to produce a composition with good mixing workability and hot melt coating adaptability because it exhibits excellent melt viscosity at high temperatures.

[0078] The storage modulus G' at 180°C was determined by measuring dynamic viscoelasticity based on temperature dispersion. Using a viscoelastic testing machine (manufactured by TA Instruments Japan, trade name: ARES G2), a hot melt adhesive composition was formed into a test piece with a thickness of approximately 2 mm. The test piece was clamped between parallel discs with a diameter of 8 mm, which served as the measuring part of the testing machine, and the storage modulus (G') was measured from 30°C to 200°C at a frequency of 1 Hz and a heating rate of 2°C / min.

[0079] From the viewpoint of reducing environmental impact, the biomass content of the hot-melt adhesive composition of the present invention is preferably 30% or more, more preferably 40% or more, and even more preferably 50% or more. The above biomass content is determined according to ASTM D6866-16.

[0080] <Morphology of Hot Melt Adhesive Compositions> The composition of the hot melt adhesive composition of the present invention has been described in detail above. The hot melt adhesive composition can be prepared by melting and mixing the above-mentioned styrene block copolymer (A) having a farnesene structure, thermoplastic resin (B), tackifying resin (C) and any component (other adhesive raw materials), or it can be prepared as a solution-type adhesive composition dissolved in a specified organic solvent (toluene, ethyl acetate, etc.).

[0081] <Applications of Hot Melt Adhesive Compositions> The hot-melt adhesive composition of the present invention is suitable for adhesive articles in the form of adhesive layers containing the adhesive composition, laminates containing the adhesive layers (e.g., adhesive tapes), etc. Hereinafter, as an example of the application of the hot-melt adhesive composition of the present invention, a double-sided adhesive tape formed by coating the above-described adhesive composition on both sides of a substrate will be described. It should be noted that, in the case of a single-sided adhesive tape, it is the same as a double-sided adhesive tape except that the adhesive composition is coated on only one side of the substrate. Furthermore, in the case of an adhesive tape without a substrate, it is the same as a double-sided adhesive tape except that the adhesive composition is coated onto a release liner to form an adhesive layer only.

[0082] A double-sided adhesive tape using the hot-melt adhesive composition of the present invention has the above-described adhesive composition coated on both sides of a substrate, and a release liner further attached to the surface of the adhesive composition as needed.

[0083] As a substrate, there are no particular restrictions on the shape, such as film or sheet, that can be coated with a hot-melt adhesive composition. For example, depending on the application of the adhesive tape, the following can be appropriately selected: plastic films such as polypropylene film, ethylene-propylene copolymer film, polyester film, polyvinyl chloride film, cellophane, polyimide, polycarbonate (PC), and polystyrene (PS); foamed sheets containing foams such as polyurethane foam, polyethylene foam, polypropylene foam, ethylene-vinyl acetate copolymer foam, butyl rubber foam, and polyacrylate foam; woven and nonwoven fabrics formed from various fibrous materials (natural fibers such as hemp and cotton, synthetic fibers such as polyester and vinylon, semi-synthetic fibers such as acetate, and metal fibers such as stainless steel); papers such as kraft paper, Japanese paper, and crepe paper; and metal foils such as aluminum foil and copper foil. As for the above-mentioned plastic films, non-stretch films, uniaxial stretch films, and biaxial stretch films can all be used. In addition, the surface of the substrate where the adhesive layer is located can be treated with a primer, corona discharge treatment, or other easy-to-bond treatments.

[0084] The thickness of the substrate can be selected appropriately according to the purpose, and is usually preferred to be above 1μm and below 2mm.

[0085] As the release liner, conventional release paper or the like can be used, without particular limitation. For example, release liners with a release treatment layer on the surface of substrates such as plastic film or paper, or release liners containing low-adhesion materials such as fluoropolymers (polytetrafluoroethylene, etc.) or polyolefin resins (polyethylene, polypropylene, etc.) can be used. The release treatment layer is formed, for example, by surface treatment of the substrate using release agents such as silicone-based, long-chain alkyl-based, or fluorine-based release agents.

[0086] Furthermore, there are no particular limitations on the method of coating the hot melt adhesive composition onto the substrate. Known methods such as dissolving the adhesive raw material in an organic solvent for coating (solution spreading method), forming a sheet from multiple hot rollers for coating (calendering method), and thermally melting the adhesive raw material for coating (hot melt method) can be used.

[0087] There are no particular limitations on the coating apparatus for hot melt adhesive compositions, and conventionally known coating machines such as roller coaters, doctor blade coaters, bar coaters, die coaters, air knife coaters, gravure coaters, variable gravure coaters, and curtain coaters can be used for coating.

[0088] The hot-melt adhesive composition of the present invention can be used for a variety of applications. Furthermore, the adhesive layer containing this adhesive composition can be used alone as an adhesive tape, and the laminate containing this adhesive layer can also be applied to a variety of applications. Examples include adhesives and adhesive tapes for fixing electronic components, fixing automotive components, surface protection, shielding, labeling, bonding, cutting tape, sealing, corrosion and water resistance, electrical insulation, semiconductor manufacturing, optical display films, adhesive optical films, electromagnetic wave shielding, or as sealing materials for electrical and electronic components.

[0089] Furthermore, hot-melt adhesive compositions eliminate the need for a drying process, thus significantly increasing coating speed and reducing production costs. Additionally, since cross-linking is unnecessary, a curing process is also eliminated, allowing for quick transfer to the next stage of production, further improving workability and reducing processing time. Moreover, by using hot-melt adhesive compositions, solvents are eliminated entirely or reduced, offering significant advantages not only economically but also environmentally.

[0090] Example Next, embodiments will be given to further illustrate the present invention in detail, but the present invention is not limited to these embodiments.

[0091] (Example 1) 100 parts by weight of a styrene-based block copolymer (A) (Septon Bio series SF902, Mw=133000, Mw / Mn=1.2, manufactured by Kuraray) and Irganox 1010 (hindered phenolic antioxidant, manufactured by BASF) were added to a heated kneader and mixed under heat (170–190°C) to achieve full melting. 50 parts by weight of a thermoplastic resin (B) (Polybutene HV-300, Mn=1400, manufactured by ENEOS) and 100 parts by weight of a tackifying resin (C) (YSPolyster TH130, hydrogenated terpene phenol, softening point 130°C, manufactured by Yasuhara Chemical) were added to the melt and further mixed under heat (140°C–190°C) to obtain a hot-melt adhesive composition. The adhesive composition was sandwiched in a 75 μm thick release PET sheet and melted using a hot press at 200°C × 2 MPa × 3 minutes to produce an adhesive sheet with a thickness of 50 μm.

[0092] (Examples 2-10, Comparative Examples 1-4) The composition of the adhesive composition was changed as shown in Tables 1-3, and the adhesive sheet was prepared by the same procedure as in Example 1.

[0093] <Instructions for Raw Materials> SF902: Septon Bio series SF902 (hydrogenated styrene-farnesene block copolymer, polymer block (A-1) / polymer block (A-2) = 18wt% / 82wt%, Mw = 133000, Mw / Mn = 1.2, manufactured by Kuraray) SF903: Septon Bio series SF903 (hydrogenated styrene-farnesene block copolymer, polymer block (A-1) / polymer block (A-2) = 30wt% / 70wt%, Mw = 243000, Mw / Mn = 1.4, manufactured by Kuraray) SF904: Septon Bio series SF904 (hydrogenated styrene-farnesene block copolymer, polymer block (A-1) / polymer block (A-2) = 21wt% / 79wt%, Mw = 78500, Mw / Mn = 1.1, manufactured by Kuraray) LV50: Nisseki Polybutene LV-50 (polybutene, Mn=430, kinematic viscosity (40℃) 110 mmHg) 2 / s, manufactured by ENEOS) LV100: Nisseki Polybutene LV-100 (Polybutene, Mn=500, Kinematic viscosity (40℃) 205 mm) 2 / s, manufactured by ENEOS) HV300: Nisseki Polybutene HV-300 (polybutene, Mn=1400, kinematic viscosity (40℃) 26000 mmHg) 2 / s, manufactured by ENEOS) HV1900: Nisseki Polybutene HV-1900 (polybutene, Mn=2900, kinematic viscosity (40℃) 160000 mm³) 2 / s, manufactured by ENEOS) TH130: YS Polyster TH130 (hydrogenated terpene phenol, softening point 130°C, manufactured by Yasuhara Chemical Co., Ltd.) UH115: YS Polyster UH115 (hydrogenated terpene phenol, softening point 115℃, manufactured by Yasuhara Chemical Co., Ltd.) PX1150N: YS RESIN PX1150N (terpene resin, softening point 115℃, manufactured by Yasuhara Chemical Co., Ltd.) P115: Arkon P-115 (hydrogenated petroleum resin, softening point 115℃, manufactured by Arakawa Chemical Industry) FTR6100: FTR6100 (aromatic hydrocarbon resin, softening point 95℃, manufactured by Mitsui Chemicals) P90: Arkon P-90 (hydrogenated petroleum resin, softening point 90℃, manufactured by Arakawa Chemical Industry) PCJ: Haritac PCJ (Polymeric Rosin Ester, Softening Point 124°C, Manufactured by Harima Chemicals) KE100: Pinecrystal KE-100 (Rosin derivative, softening point 100℃, manufactured by Arakawa Chemical). A75: Super Ester A-75 (disproportionated rosin ester, softening point 75℃, manufactured by Arakawa Chemical Industry). Irg1010: Irganox1010 (hindered phenolic antioxidant, manufactured by BASF) <Evaluation Methods> For adhesive tapes having an adhesive layer comprising a hot-melt adhesive composition prepared as described above, measurements were performed according to the method described below. The results are shown in Tables 1 to 3. It should be noted that in Comparative Example 2, the adhesive layer was not tacky, therefore it was impossible to attach the adhesive layer to the backing material or the substrate, and it was impossible to prepare the test piece required for the measurement; therefore, it was recorded as unmeasurable.

[0094] (Method for determining 180° peel adhesion) In an environment of 23°C and 50% RH, adhesive sheets prepared in the examples and comparative examples were lined with a 25 μm thick polyethylene terephthalate film on one side and cut to a length of 120 mm and a width of 20 mm. Next, the other adhesive side was attached to a stainless steel plate (obtained by finishing SUS304 with #360 sandpaper using a hairline finish). A 2 kg roller was applied to the upper surface of the adhesive sheet once, and then the sheets were left to stand for 1 hour at 23°C and 50% RH to create a test piece formed by pressing the adhesive sheet against the stainless steel plate. Then, using a Tensilon tensile testing machine, with the stainless steel plate constituting the test piece fixed, the strength of the adhesive sheet when peeled along a 180° direction at a tensile speed of 300 mm / min was measured.

[0095] (Shear holding force) In an environment of 23°C and 50% RH, the adhesive tapes prepared in the examples and comparative examples were backed with 50 μm thick aluminum foil on one side and then cut to a length of 100 mm and a width of 20 mm. Next, the adhesive side of the cut adhesive tape 2 was arranged to have a bonding area of ​​20 mm × 20 mm (4 cm). 2 The adhesive tape 2 is attached to a stainless steel plate 3 (obtained by polishing SUS304 with #360 sandpaper using a brushed finish). A 2kg roller is then applied to the upper surface of the adhesive tape 2 once to apply pressure, thus creating test piece 1. Test piece 1, formed by pressing the adhesive tape 2 and the stainless steel plate 3 together, is then created by allowing the tape to stand for 1 hour at a temperature of 23°C and a relative humidity of 50%RH.

[0096] Next, the portion of the adhesive tape 2 of test piece 1 that is not attached to the stainless steel plate 3 is folded. After fixing the stainless steel plate 3 side of test piece 1 to a holding force gauge at a measurement temperature of 70°C, a 500g weight 3 is installed on the folded portion of the adhesive tape 2. The piece is then placed at 70°C with the weight 3 installed, and the time until the adhesive tape 2 peels off (falls) is measured (the concept of the measurement method is illustrated in the diagram below). Figure 1 It should be noted that if the experiment is maintained for 1440 minutes, the end of the experiment is recorded as "1440 <".

[0097] (Constant load holding force) In an environment of 23°C and 50%RH relative humidity, the adhesive tapes prepared in the examples and comparative examples were lined with a 25μm thick polyethylene terephthalate film on one side and cut to a length of 100mm and a width of 10mm. Then, the adhesive side of the cut adhesive tape 6 was attached to a stainless steel plate 7 (obtained by finishing the SUS304 with hairline sandpaper using #360 sandpaper) with an attachment length of 50mm. After applying one reciprocating pressure to the upper surface of the adhesive tape 6 with a 2kg roller, it was left to stand for 1 hour at a temperature of 40°C, thereby producing a test piece 5 formed by pressing the adhesive tape 6 and the stainless steel plate 7 together.

[0098] Next, the stainless steel plate 7 side of the test piece 5 was fixed to the constant load holding force gauge with the adhesive tape facing down. A 100g weight 8 was then installed on the portion of the adhesive tape 6 not attached to the stainless steel plate 7. The test piece was placed in an environment with the weight 8 installed at 23°C and 50% RH, and the time until the adhesive tape 6 peeled off (fell) was measured (the concept of the measurement method is illustrated in...). Figure 2 It should be noted that if the experiment is maintained for 180 minutes, the end of the experiment is recorded as "180 <".

[0099] (Method for determining re-peelability) In an environment of 23°C and 50% RH, the adhesive sheets prepared in the examples and comparative examples were lined with a 25 μm thick polyethylene terephthalate film on one side and cut to a length of 120 mm and a width of 20 mm. Next, the other adhesive side was attached to a stainless steel plate (obtained by finishing the SUS304 with #360 sandpaper using a hairline finish). A 2 kg roller was then applied to the upper surface of the adhesive sheet once, and the sheets were left to stand for 72 hours at 23°C and 50% RH to produce a test piece formed by pressing the adhesive sheet against a stainless steel plate.

[0100] Next, with the stainless steel plate constituting the above test piece fixed, the adhesive sheet was peeled off at a stretching speed of 20 m / min along a 135° direction, and the presence of residual adhesive or contamination of the adhesive on the stainless steel plate was visually evaluated.

[0101] ◎: The adhesive layer peels off from the stainless steel plate interface without leaving any residue or contamination.

[0102] 〇: Slight traces of glue remain on the surface of the stainless steel sheet, but the adhesive layer has peeled off at the interface between the adhesive layer and the stainless steel sheet.

[0103] ×: This causes damage to the adhesive layer, resulting in interlayer peeling between the polyethylene terephthalate film and the adhesive layer, leading to residue and contamination.

[0104] (Methods for determining compatibility) In an environment of 23°C and 50% RH, a glass sheet (manufactured by Nippon Sheet Glass Co., Ltd.) with a thickness of 1 mm, a length of 50 mm, and a width of 50 mm was attached to one side of the adhesive sheet prepared in the examples and comparative examples. The structure of the glass, adhesive layer, and PET release film was used as a test piece. The haze of the test piece was measured using a reflectance-transmittance meter (HM-100, manufactured by Murakami Color Technology Research Institute Co., Ltd.). It should be noted that the haze of the glass monomer used in the preparation of the test piece was 0.7%, and the haze of the PET release film monomer was 4.8%.

[0105] (Method for determining energy storage modulus G') The adhesive layers prepared in the examples and comparative examples were overlapped to a thickness of approximately 2 mm, and then punched into test pieces with a diameter of 8 mm. The test pieces were clamped in a viscoelasticity testing machine (ARESG2, manufactured by TA Instruments Japan) with a parallel plate of 8 mm diameter, and the test pieces were measured at a frequency of 1 Hz and a heating rate of 2 °C / min to determine the storage modulus G' at 180 °C.

[0106] (Weight-average molecular weight (GPC) of adhesive resin) The weight-average molecular weight specified in this specification refers to the value determined by gel permeation chromatography (GPC) and converted to standard polystyrene. Specifically, the above-mentioned weight-average molecular weight can be determined using a GPC apparatus (HLC-8320GPC) manufactured by Tosoh Corporation under the following conditions.

[0107] • Sample concentration: 0.5% by mass (tetrahydrofuran solution) • Sample injection volume: 100 μl • Eluent: Tetrahydrofuran • Flow rate: 1.0 ml / min • Measurement temperature: 40℃ ·This column: 1 piece of TSKgelG5000HXL + 1 piece of TSKgelG4000HXL + 1 piece of TSKgelG3000HXL + 2 pieces of TSKgelG2500HXL • Protective pillar: TSKgel HXL-H • Detector: Differential refractometer • Weight average molecular weight of standard polystyrene: 5 million to 5 million (manufactured by Tosoh Corporation) [Table 1]

[0108] [Table 2]

[0109] [Table 3]

[0110] As shown in Tables 1-3, the hot-melt adhesive composition of the present invention contains a large amount of plant-derived components and exhibits excellent adhesive properties, particularly 180° peel strength, constant load holding force, and shear holding force, and further demonstrates excellent results in terms of high re-peelability. On the other hand, the shear strength of Comparative Example 1, which has a content of tackifying resin (C) outside the scope of the present invention, is poor, and it does not have sufficient adhesive performance as an adhesive tape for fixing parts. The softening point of tackifying resin (C) in Comparative Example 2, which is outside the scope of the present invention, is not tacky and cannot be used for measurement. The kinematic viscosity (40°C) of thermoplastic resin (B) in Comparative Example 3, which is outside the scope of the present invention, and the softening point of tackifying resin (C) in Comparative Example 4, both show poor re-peelability.

Claims

1. A hot-melt adhesive composition, characterized in that, It contains at least a styrene-based block copolymer (A) with a farnesene structure, a thermoplastic resin (B), and a tackifying resin (C). The kinematic viscosity of the thermoplastic resin (B) is 150 mmHg at 40°C. 2 / s or higher and 200,000 mm 2 / s or less, or a number-average molecular weight Mn of 450 or more but less than 4000. The softening point of the tackifying resin (C) is above 100°C. The hot-melt adhesive composition contains 30 to 500 parts by weight of the tackifying resin (C) relative to 100 parts by weight of the styrene-based block copolymer (A).

2. The hot melt adhesive composition according to claim 1, wherein, The styrene-based block copolymer (A) comprises polymer blocks (A-1) containing structural units derived from styrene and polymer blocks (A-2) containing structural units derived from farnesene.

3. The hot melt adhesive composition according to claim 1, wherein, The kinematic viscosity of the thermoplastic resin (B) is 20,000 mm³ at 40°C. 2 / s or higher and 200,000 mm 2 / s or less, or a number-average molecular weight Mn of 1000 or more but less than 4000.

4. The hot melt adhesive composition according to claim 1, wherein, The weight-average molecular weight (Mw) of the styrene-based block copolymer (A) is 10,000 to 500,000.

5. The hot melt adhesive composition according to claim 2, wherein, The content of the polymer block (A-1) in the total amount of the styrene-based block copolymer (A) is less than 35% by mass.

6. The hot melt adhesive composition according to claim 1, wherein, The thermoplastic resin (B) is contained in 5 to 300 parts by weight relative to 100 parts by weight of the styrene block copolymer (A).

7. The hot melt adhesive composition according to claim 1, wherein, The thermoplastic resin (B) is liquid at 23°C.

8. The hot melt adhesive composition according to claim 1, wherein, The thermoplastic resin (B) contains an olefin-based resin.

9. The hot melt adhesive composition according to claim 1, wherein, The haze of the adhesive layer with a thickness of 40 μm obtained from the hot melt adhesive composition is less than 10%.

10. The hot melt adhesive composition according to claim 1, wherein, The storage modulus G' of the hot melt adhesive composition at 180°C is 5 × 10⁻⁶. 3 the following.

11. The hot melt adhesive composition according to claim 1, wherein, The biomass content of the hot-melt adhesive composition is 30% or more.

12. The hot melt adhesive composition according to claim 1, wherein, The hot melt adhesive composition contains one or more selected from anti-aging agents, ultraviolet absorbers, heat stabilizers and resin reinforcing agents.

13. An adhesive tape, characterized in that, It contains an adhesive layer comprising the hot melt adhesive composition according to any one of claims 1 to 12.

14. An article characterized in that, The adhesive tape of claim 13 was used.

Images