Adhesive, adhesive tape, and method for fixing electronic device component or in-vehicle component

Abstract

To provide: an adhesive capable of exhibiting excellent adhesive force while having a high bio-derived carbon content; an adhesive tape employing the adhesive; and a method for fixing an electronic device component or an in-vehicle component.SOLUTION: The adhesive contains a (meth)acrylic copolymer that contains 48 wt.% or more of structural units derived from a monomer A represented by a general formula (1) containing bio-derived carbon and / or a monomer B represented by a general formula (2) containing bio-derived carbon, and that has a glass transition temperature equal to or lower than -20°C.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to an adhesive, an adhesive tape, and a method for fixing an electronic device component or an in-vehicle component. [Background technology]

[0002] Conventionally, adhesive tapes having an adhesive layer containing an adhesive have been widely used when fixing parts in electronic components, vehicles, houses, and building materials. Specifically, adhesive sheets are used to adhere a cover panel for protecting the surface of a portable electronic device to a touch panel module or a display panel module, or to adhere a touch panel module to a display panel module (e.g., Patent Documents 1 to 3). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2015-052050 A [Patent Document 2] JP 2015-021067 A [Patent Document 3] JP 2015-120876 A Summary of the Invention [Problem to be solved by the invention]

[0004] In recent years, the depletion of petroleum resources and the emission of carbon dioxide from the combustion of petroleum-derived products have become problems. Therefore, attempts have been made to conserve petroleum resources by using bio-derived materials instead of petroleum-derived materials, mainly in the medical and packaging fields. Such attempts have spread to all fields, and the use of bio-derived materials is now being sought in the field of adhesives and adhesive tapes.

[0005] As an adhesive with excellent adhesive strength, (meth)acrylic adhesives containing (meth)acrylic copolymers are widely used. Even with (meth)acrylic adhesives, it has been possible to select and use biologically derived materials, such as rosin or terpene, as a tackifier. However, it is difficult to achieve excellent adhesive strength while using many biologically derived materials.

[0006] The present invention aims to provide an adhesive that can exhibit excellent adhesive strength while increasing the content of biological carbon, an adhesive tape using the adhesive, and a method for fixing electronic device components or vehicle-mounted components. [Means for solving the problem]

[0007] The present invention relates to a pressure-sensitive adhesive comprising a (meth)acrylic copolymer that contains 48% by weight or more of structural units derived from monomer A represented by the following general formula (1) containing bio-derived carbon and / or monomer B represented by the following general formula (2) containing bio-derived carbon, and has a glass transition temperature of -20°C or lower.

[0008] [ka]

[0009] In formula (1), R 1 represents H or CH3, R 2 -C n H 2n+1 and n represents an integer of 7 to 14. In formula (2), R 3 is -C(=O)C m H 2m+1 and m represents an integer of 7 to 13. R 2 and R 3 The carbon in it is of biological origin. The present invention will be described in detail below.

[0010] As a result of intensive research, the inventors have found that by selecting monomer A (hereinafter also simply referred to as "monomer A") containing bio-derived carbon and represented by the above general formula (1) and / or monomer B (hereinafter also simply referred to as "monomer B") containing bio-derived carbon and represented by the above general formula (2) as raw materials for the (meth)acrylic copolymer that constitutes the adhesive, and adjusting the glass transition temperature of the (meth)acrylic copolymer to be -20°C or lower, it is possible to obtain an adhesive that can exhibit excellent adhesive strength while increasing the content of bio-derived carbon.

[0011] The pressure-sensitive adhesive according to one embodiment of the present invention contains a (meth)acrylic copolymer. Such a (meth)acrylic pressure-sensitive adhesive can exhibit excellent adhesive strength by selecting a monomer as a raw material.

[0012] In the present invention, the above-mentioned monomer A and / or monomer B are contained as monomers serving as raw materials for the (meth)acrylic pressure-sensitive adhesive. These monomers can be obtained cheaply and easily by alcoholizing and esterifying saturated and unsaturated fatty acids extracted from plants and animals. If monomer A and monomer B, which contain plant-derived carbon, are used, they are resources that are originally generated by absorbing carbon dioxide from the atmosphere, so even if they are burned, the total amount of carbon dioxide in the atmosphere will not increase. These monomers have relatively low glass transition temperatures as homopolymers, and adhesives composed of these monomers are easy to exhibit their adhesive function. Therefore, by using a relatively large amount of these monomers to increase the content of carbon derived from living organisms in the adhesive as a whole, and by optionally combining them with other non-living monomers, an adhesive that can exhibit sufficient adhesive strength can be obtained.

[0013] R in formula (1) 2 , and R in formula (2) 3 The alkyl group contained in may be linear or branched. A linear alkyl group is preferred because it has a high cohesive strength and can provide a higher adhesive strength.

[0014] Specific examples of the monomer A include n-octyl (meth)acrylate, lauryl (meth)acrylate, n-decyl (meth)acrylate, n-heptyl acrylate, 2-octyl (meth)acrylate, n-nonyl (meth)acrylate, undecyl (meth)acrylate, tetradecyl (meth)acrylate, and myristyl (meth)acrylate. These monomers A may be used alone or in combination of two or more. Among them, at least one selected from the group consisting of n-octyl (meth)acrylate, lauryl (meth)acrylate, and decyl (meth)acrylate is preferred because they are particularly easy to obtain, have a low glass transition temperature of the homopolymer, and are easy to exhibit the adhesive function composed of such a monomer. Among them, it is more preferable that the monomer A contains lauryl acrylate and / or lauryl methacrylate, and even more preferable that it contains lauryl acrylate and lauryl methacrylate, because an adhesive having excellent shear strength can be obtained.

[0015] Specific examples of the monomer B include vinyl caprate, vinyl laurate, vinyl caprylate, vinyl nonanoate, etc. These monomers B may be used alone or in combination of two or more. Among them, vinyl caprate and / or vinyl laurate are preferred because they are particularly easy to obtain, have a low glass transition temperature of the homopolymer, and are easy to exhibit the adhesive function composed of such monomers.

[0016] The (meth)acrylic copolymer contains 48% by weight or more of the structural units derived from the monomer A and / or monomer B. This allows the copolymer to exhibit excellent adhesive strength while increasing the content of carbon derived from living organisms. From the viewpoint of further increasing the adhesive strength, the (meth)acrylic copolymer more preferably contains 55% by weight or more of the structural units derived from the monomer A and / or monomer B, even more preferably contains 65% by weight or more, particularly preferably contains 75% by weight or more, and usually contains 100% by weight or less.

[0017] When the (meth)acrylic copolymer contains structural units derived from the monomer A, from the viewpoint of further enhancing adhesive strength, it is preferable that, among the structural units derived from the monomer A, structural units derived from lauryl acrylate and / or lauryl methacrylate account for 48% by weight or more. The content of the structural units derived from the lauryl acrylate in the total of the structural units derived from the lauryl acrylate and / or lauryl methacrylate is preferably 10% by weight or more and 90% by weight or less, more preferably 15% by weight or more and 85% by weight or less, and even more preferably 19% by weight or more and 77% by weight or less. Furthermore, the content of the structural units derived from the above-mentioned methaurauryl acrylate in the total of the structural units derived from the above-mentioned lauryl acrylate and / or lauryl methacrylate is preferably 10% by weight or more and 90% by weight or less, more preferably 15% by weight or more and 85% by weight or less, and even more preferably 19% by weight or more and 77% by weight or less.

[0018] The (meth)acrylic copolymer may contain a constituent unit derived from a monomer other than the monomer A and monomer B. The other monomer is not particularly limited, and examples thereof include (meth)acrylic acid alkyl esters such as methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, n-butyl (meth)acrylate, tert-butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, n-octyl (meth)acrylate, isooctyl (meth)acrylate, n-nonyl (meth)acrylate, isononyl (meth)acrylate, myristyl (meth)acrylate, cetyl (meth)acrylate, stearyl (meth)acrylate, esters of 5,7,7-trimethyl-2-(1,3,3-trimethylbutyl)octanol-1 and (meth)acrylic acid, esters of alcohols having a total of 18 carbon atoms and having 1 or 2 methyl groups in a linear main chain and (meth)acrylic acid, behenyl (meth)acrylate, and arachidyl (meth)acrylate. Further examples include cyclohexyl (meth)acrylate, isobornyl (meth)acrylate, benzyl (meth)acrylate, 2-butoxyethyl (meth)acrylate, 2-phenoxyethyl (meth)acrylate, tetrahydrofurfuryl (meth)acrylate, and polypropylene glycol mono(meth)acrylate. Furthermore, for example, (meth)acrylic acid esters having a hydroxyl group, such as 4-hydroxybutyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, and tetrahydrofurfuryl (meth)acrylate, can be used. For example, monomers having a carboxyl group, such as (meth)acrylic acid, can be used. For example, monomers having a glycidyl group, such as glycidyl (meth)acrylate, can be used. For example, monomers having an amide group, such as hydroxyethyl (meth)acrylamide, isopropyl (meth)acrylamide, and dimethylaminopropyl (meth)acrylamide, can be used. Monomers having a nitrile group, such as (meth)acrylonitrile, can be used. Furthermore, various monomers used in general (meth)acrylic polymers, such as vinyl carboxylates such as vinyl acetate, acrylonitrile, and styrene, can also be used. These monomers may be used alone or in combination of two or more kinds.

[0019] In particular, from the viewpoint of improving adhesion to resins such as polypropylene and olefin-based resins such as acrylic, the (meth)acrylic copolymer preferably has a structural unit derived from an alkyl ester (meth)acrylate having an alkyl group having 16 to 24 carbon atoms (preferably 18 to 23, more preferably 20 to 22) as the other monomer.

[0020] The other monomers preferably contain carbon derived from living organisms, but may be non-living monomers that do not contain carbon derived from living organisms. In theory, it is also possible to use monomers that contain carbon derived from living organisms as raw materials for the acrylic copolymer. From the viewpoint of the cost and productivity of the adhesive, a monomer containing carbon derived from living organisms that is relatively inexpensive and easy to obtain may be used, and the other monomers may be combined with monomers containing carbon derived from petroleum.

[0021] The (meth)acrylic copolymer has a glass transition temperature of -20°C or lower. This allows the resulting adhesive to exhibit excellent adhesive strength. From the viewpoint of further increasing adhesive strength, the glass transition temperature of the (meth)acrylic copolymer is preferably -30°C or lower, more preferably -40°C or lower, and particularly preferably -50°C or lower. The glass transition temperature of the (meth)acrylic copolymer is usually -90°C or higher, and preferably -80°C or higher. The glass transition temperature of the (meth)acrylic copolymer can be determined, for example, by differential scanning calorimetry.

[0022] The weight average molecular weight of the (meth)acrylic copolymer is not particularly limited, but the preferred lower limit is 300,000, and the preferred upper limit is 2,000,000. When the weight average molecular weight of the (meth)acrylic copolymer is within this range, the resulting adhesive can exhibit excellent adhesive strength. The more preferred lower limit of the weight average molecular weight of the (meth)acrylic copolymer is 400,000, the more preferred upper limit is 1,800,000, the even more preferred lower limit is 500,000, and the particularly preferred lower limit is 1,000,000. In this specification, the weight average molecular weight means a polystyrene-equivalent molecular weight determined by GPC measurement.

[0023] The (meth)acrylic copolymer can be obtained by subjecting a mixture of the raw monomers to a radical reaction in the presence of a polymerization initiator. The radical reaction method is not particularly limited, and examples thereof include living radical polymerization, free radical polymerization, etc. According to living radical polymerization, a copolymer having a more uniform molecular weight and composition can be obtained compared to free radical polymerization, and the generation of low molecular weight components, etc. can be suppressed, and the cohesive force of the pressure-sensitive adhesive layer can be increased. The polymerization method is not particularly limited, and a conventionally known method can be used. For example, solution polymerization (boiling point polymerization or constant temperature polymerization), emulsion polymerization, suspension polymerization, bulk polymerization, etc. Among them, solution polymerization is preferred because of its simple synthesis.

[0024] When solution polymerization is used as the polymerization method, examples of the reaction solvent include ethyl acetate, toluene, methyl ethyl ketone, methyl sulfoxide, ethanol, acetone, diethyl ether, etc. These reaction solvents may be used alone or in combination.

[0025] The polymerization initiator is not particularly limited, and examples thereof include organic peroxides and azo compounds. Examples of the organic peroxides include 1,1-bis(t-hexylperoxy)-3,3,5-trimethylcyclohexane, t-hexylperoxypivalate, t-butylperoxypivalate, 2,5-dimethyl-2,5-bis(2-ethylhexanoylperoxy)hexane, t-hexylperoxy-2-ethylhexanoate, t-butylperoxy-2-ethylhexanoate, t-butylperoxyisobutyrate, t-butylperoxy-3,5,5-trimethylhexanoate, and t-butylperoxylaurate. Examples of the azo compounds include azobisisobutyronitrile and azobiscyclohexanecarbonitrile. These polymerization initiators may be used alone or in combination. In the case of living radical polymerization, the polymerization initiator may be, for example, an organic tellurium polymerization initiator. The organic tellurium polymerization initiator is not particularly limited as long as it is one that is generally used in living radical polymerization, and may be, for example, an organic tellurium compound, an organic telluride compound, etc. In addition to the organic tellurium polymerization initiator, an azo compound may be used as the polymerization initiator in living radical polymerization in order to accelerate the polymerization rate.

[0026] The pressure-sensitive adhesive according to one embodiment of the present invention preferably further contains a crosslinking agent, from the viewpoint of being able to appropriately adjust the gel fraction. The crosslinking agent is not particularly limited, and examples thereof include isocyanate-based crosslinking agents, aziridine-based crosslinking agents, epoxy-based crosslinking agents, and metal chelate-type crosslinking agents.

[0027] The pressure-sensitive adhesive according to one embodiment of the present invention preferably further contains a tackifier, from the viewpoint of improving adhesion to an adherend. Examples of the tackifier include rosin-based tackifiers such as rosin-based resins, rosin ester-based resins, and hydrogenated rosin-based resins; terpene-based tackifiers such as terpene-based resins and terpene-phenol-based resins; coumarone-indene-based resins, alicyclic saturated hydrocarbon-based resins, C5-based petroleum resins, C9-based petroleum resins, and C5-C9 copolymerized petroleum resins. These tackifier resins may be used alone or in combination of two or more. Among these, rosin-based tackifiers and terpene-based tackifiers derived from living organisms are preferred. Examples of the tackifiers derived from living organisms include rosin-based resins derived from natural resins such as pine resin, and terpene-based resins derived from essential oils of plants.

[0028] When the pressure-sensitive adhesive layer contains the tackifier, the content of the tackifier is not particularly limited, but a preferred lower limit is 10 parts by weight and a preferred upper limit is 50 parts by weight relative to 100 parts by weight of the (meth)acrylic copolymer. When the content of the tackifier is within this range, the resulting pressure-sensitive adhesive can exhibit sufficient adhesive strength.

[0029] The adhesive according to one embodiment of the present invention may contain additives such as a silane coupling agent, a plasticizer, an emulsifier, a softener, a filler, a pigment, a dye, etc. It is preferable to select biologically derived materials as far as possible for these additives.

[0030] The adhesive according to one embodiment of the present invention preferably has a biological carbon content of 40% by weight or more. A biological carbon content of 40% by weight or more is an indicator of a "bio-based product." From the viewpoint of reducing the environmental burden as an adhesive tape, the biological carbon content of the adhesive according to one embodiment of the present invention is more preferably 60% by weight or more, and is usually 100% by weight or less. Biogenic carbon contains a certain percentage of radioisotope (C-14), whereas petroleum-derived carbon contains almost no C-14. Therefore, the content of biogenic carbon can be calculated by measuring the concentration of C-14 in the adhesive tape. Specifically, this can be measured according to ASTM D6866, a standard used in many bioplastic industries.

[0031] The present invention also includes an adhesive tape having an adhesive layer containing the above-mentioned adhesive. The adhesive tape of one embodiment of the present invention may be a non-support tape having no substrate, a single-sided adhesive tape having an adhesive layer on one side of a substrate, or a double-sided adhesive tape having adhesive layers on both sides of a substrate.

[0032] The substrate is not particularly limited, and any conventionally known substrate can be used. In order to increase the content of biological carbon in the entire pressure-sensitive adhesive tape, however, it is preferable to use a substrate of biological origin. Examples of the above-mentioned biological substrates include polyesters (PES) such as plant-derived polyethylene terephthalate (PET), polyethylene furanoate (PEF), polylactic acid (PLA), polytrimethylene terephthalate (PTT), polybutylene terephthalate (PBT), and polybutylene succinate (PBS); films and nonwoven fabrics made of polyethylene (PE), polypropylene (PP), polyurethane (PU), triacetyl cellulose (TAC), cellulose, polyamide (PA), and the like.

[0033] From the viewpoint of substrate strength, the substrate is preferably a film made of PES or a film made of PA, and from the viewpoint of heat resistance and oil resistance, a film made of PA is more preferable. Examples of PA film constituents include nylon 11, nylon 1010, nylon 610, nylon 510, nylon 410, etc., which are made from castor oil, and nylon 56, etc., which are made from cellulose.

[0034] In addition, from the viewpoint of reducing the use of new petroleum resources and reducing the environmental load by suppressing carbon dioxide emissions, a substrate using recycled resources may be used. Examples of resource recycling methods include collecting waste such as packaging containers, home appliances, automobiles, construction materials, and food waste, and waste generated in the manufacturing process, and using the extracted materials again as raw materials by cleaning, decontamination, or decomposition by heating or fermentation. Examples of substrates using recycled resources include films and nonwoven fabrics made of PET, PBT, PE, PP, PA, etc., using raw materials made of recycled plastics re-resinized. In addition, the collected waste may be burned and used as thermal energy for the production of substrates and their raw materials, and the oils and fats contained in the collected waste may be mixed with petroleum, fractionated, and refined, and used as raw materials.

[0035] In another embodiment of the present invention, the substrate may be a foam substrate with a view to improving compressive properties. The foam base material is preferably a foam base material made of PE, PP, and / or PU, and more preferably a foam base material made of PE from the viewpoint of achieving both high flexibility and strength. Examples of the components of the foam base material made of PE include PE made from sugar cane.

[0036] The method for producing the foam base material is not particularly limited, but a preferred method is, for example, to prepare a foamable resin composition containing a PE resin containing PE derived from sugar cane as a raw material and a foaming agent, and foam the foaming agent when extruding the foamable resin composition into a sheet using an extruder, and crosslink the obtained polyolefin foam as necessary.

[0037] The thickness of the foam substrate is not particularly limited, but the preferred lower limit is 50 μm and the preferred upper limit is 300 μm. When the thickness of the foam substrate is within this range, the foam substrate can exhibit high impact resistance while exhibiting high flexibility that allows the substrate to be bonded in close contact with the shape of the adherend.

[0038] The pressure-sensitive adhesive layer has a gel fraction of preferably 10% by weight at the lower limit, more preferably 20% by weight at the lower limit, and preferably 70% by weight at the upper limit, more preferably 50% by weight at the upper limit. When the gel fraction is within this range, the resulting pressure-sensitive adhesive tape can exhibit sufficient adhesive strength. The gel fraction is measured as follows. First, the adhesive tape is cut into a flat rectangular shape of 50 mm x 100 mm to prepare a test piece, which is then immersed in ethyl acetate at 23°C for 24 hours, removed from the ethyl acetate, and dried at 110°C for 1 hour. The weight of the dried test piece is measured, and the gel fraction is calculated using the following formula. Note that no release film for protecting the adhesive layer is laminated on the test piece. Gel fraction (weight%) = 100 × (W2-W0) / (W1-W0) (W0: weight of substrate, W1: weight of test piece before immersion, W2: weight of test piece after immersion and drying)

[0039] The thickness of the pressure-sensitive adhesive layer is not particularly limited, but the preferred lower limit is 10 μm and the preferred upper limit is 100 μm. When the thickness of the pressure-sensitive adhesive layer is within this range, the resulting pressure-sensitive adhesive tape can exhibit sufficient adhesive strength.

[0040] In the pressure-sensitive adhesive tape according to one embodiment of the present invention, the total thickness (total thickness of the substrate and the pressure-sensitive adhesive layer) of the pressure-sensitive adhesive tape preferably has a lower limit of 10 μm and an upper limit of 400 μm. When the total thickness of the pressure-sensitive adhesive tape is within this range, the resulting pressure-sensitive adhesive tape can exhibit sufficient adhesive strength.

[0041] The method for producing the pressure-sensitive adhesive tape according to one embodiment of the present invention is not particularly limited, and the tape may be produced by a conventionally known production method. For example, in the case of a double-sided pressure-sensitive adhesive tape, the following method may be mentioned. First, a solution of adhesive A is prepared by adding a solvent to the (meth)acrylic copolymer and, if necessary, a crosslinking agent, a tackifier, etc., and this solution of adhesive A is applied to the surface of a substrate, and the solvent in the solution is completely dried and removed to form an adhesive layer A. Next, a release film is superimposed on the formed adhesive layer A with its release-treated surface facing the adhesive layer A. Next, a release film other than the above release film is prepared, a solution of adhesive B is applied to the release-treated surface of this release film, and the solvent in the solution is completely dried and removed to produce a laminated film in which adhesive layer B is formed on the surface of the release film. The obtained laminated film is superimposed on the back surface of the substrate on which adhesive layer A is formed, with adhesive layer B facing the back surface of the substrate to produce a laminate. Then, by pressing the above laminate with a rubber roller or the like, a double-sided adhesive tape having adhesive layers on both sides of the substrate and the surfaces of the adhesive layers covered with release films can be obtained.

[0042] Alternatively, two sets of laminate films may be prepared in a similar manner, and these laminate films may be superimposed on each side of a substrate with the adhesive layer of the laminate film facing the substrate to produce a laminate. This laminate may then be pressed with a rubber roller or the like to obtain a double-sided adhesive tape having adhesive layers on both sides of the substrate and the surface of the adhesive layer covered with a release film.

[0043] The application of the pressure-sensitive adhesive tape according to one embodiment of the present invention is not particularly limited, but since it has excellent adhesive strength and heat resistance, it can be particularly suitably used for fixing electronic equipment parts and vehicle-mounted parts. Specifically, the pressure-sensitive adhesive tape according to one embodiment of the present invention can be suitably used for adhesively fixing electronic equipment parts in large portable electronic devices, adhesively fixing vehicle-mounted parts (for example, vehicle-mounted panels), etc.

[0044] In another embodiment of the present invention, there is also provided a method for fixing an electronic device component or an on-vehicle component using the above-mentioned adhesive tape, which not only enables the electronic device component or the on-vehicle component to be firmly fixed, but also enables the fixing to continue even when exposed to high temperatures. Effect of the Invention

[0045] According to the present invention, it is possible to provide an adhesive that can exhibit excellent adhesive strength while increasing the content of biological carbon, an adhesive tape using the adhesive, and a method for fixing electronic device components or vehicle-mounted components. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0046] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples.

[0047] <Monomer A> (1) Preparation of lauryl acrylate containing bio-derived carbon Lauryl acrylate was prepared by the esterification reaction of acrylic acid with lauryl alcohol, which was prepared by hydrolyzing oils and fats such as those contained in palm kernel oil and coconut oil, fractionating the resulting fatty acids, and reducing the lauric acid with hydrogen.

[0048] (2) Preparation of lauryl methacrylate containing bio-derived carbon Lauryl methacrylate was prepared by esterifying methacrylic acid with lauryl alcohol obtained by the method described above.

[0049] (3) Preparation of n-decyl methacrylate containing bio-derived carbon n-Decyl methacrylate was prepared by esterification of methacrylic acid with n-decyl alcohol, which was prepared by hydrolyzing oils and fats such as palm kernel oil and coconut oil, fractionating the resulting fatty acids, and reducing capric acid with hydrogen.

[0050] (4) Preparation of n-octyl acrylate containing bio-derived carbon n-Octyl acrylate was prepared by the esterification reaction of acrylic acid with n-octyl alcohol. n-Octyl alcohol was prepared by hydrolyzing oils and fats such as those contained in palm kernel oil and coconut oil, and then fractionally distilling the resulting fatty acids to extract caprylic acid, which was then reduced with hydrogen.

[0051] (5) Preparation of isobornyl acrylate containing bio-derived carbon Isobornyl acrylate was prepared by reacting acrylic acid with camphene. The reaction of acrylic acid with camphene was carried out according to the method described in JP 2006-69944 A. Camphene was obtained by isomerizing α-pinene obtained from pine resin or pine essential oil.

[0052] <Monomer B> (1) Preparation of vinyl laurate containing bio-derived carbon Vinyl laurate was prepared by hydrolyzing oils and fats such as those contained in palm kernel oil and coconut oil, and then vinylating the lauric acid extracted by fractional distillation of the resulting fatty acids.

[0053] (2) Preparation of vinyl caprate containing bio-derived carbon Vinyl caprate was prepared by hydrolyzing oils and fats such as those contained in palm kernel oil and coconut oil, and then vinylating the capric acid extracted by fractional distillation of the resulting fatty acids.

[0054] <Monomers containing carbon derived from living organisms other than Monomer A and Monomer B> Stearyl acrylate was prepared by esterification of acrylic acid with stearyl alcohol, which was prepared by hydrolyzing oils and fats such as palm oil, palm kernel oil, soybean oil, and rapeseed oil, and then fractionally distilling the resulting fatty acids to obtain stearic acid, followed by hydrogen reduction.

[0055] <Non-biological monomers> As non-biological monomers, the following commercially available monomers were prepared. (1) 2-Ethylhexyl acrylate (Mitsubishi Chemical Corporation, glass transition temperature: -70°C) (2) Butyl acrylate (Mitsubishi Chemical Corporation, glass transition temperature -55°C) (3) Ethyl acrylate (Mitsubishi Chemical Corporation, glass transition temperature -20°C) (4) Methyl acrylate (Mitsubishi Chemical Corporation, glass transition temperature -8°C) (5) Acrylic acid (manufactured by Nippon Shokubai Co., Ltd., glass transition temperature 106°C) (6) Hydroxyethyl acrylate (Osaka Organic Chemical Industry Co., Ltd., glass transition temperature: -15°C)

[0056] <Crosslinking agent> As the crosslinking agent, a commercially available polyisocyanate-based crosslinking agent (Coronate L-45, manufactured by Tosoh Corporation) was prepared.

[0057] <Tackifier> As the tackifier, the following commercially available tackifiers containing biological carbon were prepared. (1) Terpene phenol resin A (Yasuhara Chemical Co., Ltd., G150, softening point: 150°C, bio-derived carbon content: 67% by weight) (2) Polymerized rosin ester resin B (hydroxyl value: 46, softening point: 152°C, bio-derived carbon content: 95% by weight) (3) Hydrogenated rosin ester resin C (KE359, manufactured by Arakawa Chemical Industries, Ltd., hydroxyl value: 40, softening point: 100°C, bio-derived carbon content: 95% by weight)

[0058] Example 1 (1) Preparation of (meth)acrylic copolymer Ethyl acetate was added as a polymerization solvent into the reaction vessel, and after bubbling with nitrogen, the reaction vessel was heated while flowing in nitrogen to start reflux. Next, a polymerization initiator solution in which 0.1 parts by weight of azobisisobutyronitrile was diluted 10 times with ethyl acetate was added into the reaction vessel as a polymerization initiator, and 34 parts by weight of lauryl acrylate, 48 parts by weight of n-octyl acrylate, 14 parts by weight of ethyl acrylate, 3 parts by weight of acrylic acid, and 0.5 parts by weight of hydroxyethyl acrylate were added dropwise over 2 hours. After the dropwise addition was completed, a polymerization initiator solution in which 0.1 parts by weight of azobisisobutyronitrile was diluted 10 times with ethyl acetate was added again into the reaction vessel as a polymerization initiator, and a polymerization reaction was carried out for 4 hours to obtain a (meth)acrylic copolymer-containing solution.

[0059] The glass transition temperature of the obtained (meth)acrylic copolymer was measured using a differential scanning calorimeter (DSC6220, manufactured by Seiko Instruments Inc.) and was found to be -44°C.

[0060] The (meth)acrylic copolymer was diluted 50 times with tetrahydrofuran (THF), and the resulting diluted solution was filtered through a filter (material: polytetrafluoroethylene, pore size: 0.2 μm) to prepare a measurement sample. This measurement sample was fed to a gel permeation chromatograph (Waters, 2690 Separations Model) and subjected to GPC measurement under conditions of a sample flow rate of 1 milliliter / min and a column temperature of 40°C, and the polystyrene-equivalent molecular weight of the (meth)acrylic copolymer was measured to determine the weight average molecular weight. The weight average molecular weight was 720,000.

[0061] (2) Manufacture of adhesive tapes To the obtained (meth)acrylic copolymer-containing solution, 3 parts by weight of crosslinking agent, 10 parts by weight of terpene phenol resin A, 14 parts by weight of polymerized rosin ester resin B, and 10 parts by weight of hydrogenated rosin ester resin C were added per 100 parts by weight of (meth)acrylic copolymer to prepare an adhesive solution. This adhesive solution was applied to a 75 μm-thick release-treated PET film so that the thickness of the adhesive layer after drying was 50 μm, and then dried at 110 ° C for 5 minutes. This adhesive layer was layered on a 75 μm-thick release-treated PET film and aged at 40 ° C for 48 hours to obtain an adhesive tape (non-support type).

[0062] The release film on one side of the obtained adhesive tape was peeled off, and the tape was laminated to a PET film having a thickness of 50 μm, and cut into a flat rectangular shape of 20 mm × 40 mm. The release film on the other side of the adhesive tape was peeled off to prepare a test piece, and the weight was measured. The test piece was immersed in ethyl acetate at 23 ° C for 24 hours, and then removed from the ethyl acetate and dried at 110 ° C for 1 hour. The weight of the test piece after drying was measured, and the gel fraction was calculated using the following. The gel fraction was 38 wt%. Gel fraction (wt%)=100×(W5−W3) / (W4−W3) (W3: weight of the PET film, W4: weight of the test piece before immersion in ethyl acetate, W5: weight of the test piece after immersion in ethyl acetate and drying)

[0063] (Examples 2 to 28, Comparative Examples 1 to 5) Except for using the (meth)acrylic copolymer monomers and the tackifiers to be blended in the adhesive tape as shown in Tables 1 to 4, an adhesive tape was obtained in the same manner as in Example 1. In Example 21, a double-sided adhesive tape was produced in which an adhesive layer having a thickness of 25 μm was formed on each side of a substrate. The substrate was a 25 μm-thick film of nylon 610 (Toray Industries, Inc., CM2001), a plant-derived polyamide resin.

[0064] In Example 22, a double-sided adhesive tape having an adhesive layer of 50 μm thickness formed on each side of a foam substrate was produced by the following method. The adhesive solution was applied to a release-treated PET film having a thickness of 75 μm so that the adhesive layer after drying had a thickness of 50 μm, and then dried at 110 ° C for 5 minutes to obtain an adhesive layer A. This adhesive layer A was overlaid on a PE foam substrate having a thickness of 100 μm and an expansion ratio of 3 times, and pressed with a rubber roller or the like to produce a laminate in which the adhesive layer A was formed on the surface of the release film. Next, a release film other than the release film was prepared, coated so that the adhesive layer after drying had a thickness of 50 μm, and then dried at 110 ° C for 5 minutes to obtain an adhesive layer B. This adhesive layer B was attached to the surface of the foam of the laminate opposite to the adhesive layer A, and similarly pressed with a rubber roller or the like, and aged at 40 ° C for 48 hours to obtain a double-sided adhesive tape having adhesive layers on both sides of the foam substrate.

[0065] (evaluation) The pressure-sensitive adhesive tapes obtained in the Examples and Comparative Examples were evaluated by the following methods. The results are shown in Tables 1 to 4.

[0066] (1) Biological carbon content The content of bio-derived carbon in the obtained pressure-sensitive adhesive tape was measured in accordance with ASTM D6866.

[0067] (2) Measurement of peel strength in the plane direction A 10mm wide x 10mm wide double-sided adhesive tape was sandwiched between two SUS plates, pressed together with a 5kg weight for 10 seconds, and then cured for 24 hours at 23°C and 50% humidity. The two SUS plates were then placed on a jig so that they were horizontal, the lower SUS plate was fixed, and the upper SUS plate was pulled vertically at a pulling speed of 10mm / min, and the force (N) at which the tape peeled off was measured. The surface-direction peeling force (Pa) was calculated using the following formula: Surface direction peeling force (Pa) = force when the tape is peeled off (N) ÷ tape area (m 2 ) In addition, the pressure-sensitive adhesive tape of Example 22 had a very high peel strength in the plane direction, and the foam substrate was destroyed when the peel strength exceeded 0.8 MPa.

[0068] (3) Measurement of shear peel strength A 10mm wide x 10mm wide double-sided adhesive tape was sandwiched between two SUS plates, pressed together with a 5kg weight for 10 seconds, and then cured for 24 hours at 23°C and 50% humidity. The two SUS plates were then placed on a jig so that they were vertical, one SUS plate was fixed to the lower fixture and the other SUS plate was fixed to the upper fixture, and the upper fixture was then pulled vertically at a tensile speed of 10mm / min, and the force (N) at which the tape peeled off was measured. The shear peel strength (Pa) was calculated using the following formula: Shear direction peeling force (Pa) = force when the tape is peeled off (N) ÷ tape area (m 2 ) In addition, the pressure-sensitive adhesive tape of Example 22 had a very high peel strength in the shear direction, and the foam substrate was destroyed when the peel strength exceeded 0.8 MPa.

[0069] [Table 1]

[0070] [Table 2]

[0071] [Table 3]

[0072] [Table 4] [Industrial Applicability]

[0073] According to the present invention, it is possible to provide an adhesive that can exhibit excellent adhesive strength while increasing the content of biological carbon, an adhesive tape using the adhesive, and a method for fixing electronic device components or vehicle-mounted components.

Claims

1. An adhesive comprising a (meth)acrylic copolymer having a glass transition temperature of -20°C or lower, and a biologically derived tackifier, The (meth)acrylic copolymer contains constituent units derived from monomer A, which contains bio-derived carbon, and may or may not contain constituent units derived from monomer B, which contains bio-derived carbon and is represented by the following general formula (2), and the total content of constituent units derived from monomer A and constituent units derived from monomer B is 48% by weight or more. The monomer A is at least one selected from the group consisting of lauryl (meth)acrylate and decyl (meth)acrylate. The aforementioned biologically derived tackifier is a rosin-based tackifier and / or a terpene-based tackifier. Adhesives (excluding adhesives containing crosslinked monomers including (meth)acrylate groups and C6 to C20 olefin groups, and adhesives containing microspheres). 【Chemistry 1】 In formula (2), R ３ Ha - C (= O) C ｍ H ２ｍ＋１ This represents m, where m is an integer between 7 and 13. The carbon in R3 is of biological origin.

2. The adhesive according to claim 1, wherein the monomer B is vinyl caprate and / or vinyl laurate.

3. The adhesive according to claim 1 or 2, wherein the (meth)acrylic copolymer has a composition in which, of the constituent units derived from monomer A, 48% by weight or more are derived from lauryl acrylate and / or lauryl methacrylate.

4. The adhesive according to claim 1, 2, or 3, wherein the (meth)acrylic copolymer comprises 10 to 90% by weight of constituent units derived from monomer A, and 10 to 90% by weight of constituent units derived from lauryl acrylate.

5. The adhesive according to claim 1, 2, 3, or 4, wherein the (meth)acrylic copolymer has constituent units derived from alkyl ester (meth)acrylate having an alkyl group having 16 to 24 carbon atoms.

6. The adhesive according to claim 1, 2, 3, 4, or 5, comprising 100 parts by weight of the (meth)acrylic copolymer and / or 10 to 50 parts by weight of a bio-derived rosin-based tackifier and / or terpene-based tackifier.

7. An adhesive tape having an adhesive layer containing the adhesive according to claim 1, 2, 3, 4, 5, or 6.

8. The adhesive tape according to claim 7, further comprising a base material, wherein the base material is a film made of polyester or polyamide.

9. The adhesive tape according to claim 7, further comprising a foam substrate.

10. The adhesive tape according to claim 7, 8, or 9, used for fixing electronic equipment components or in-vehicle components.

11. A method for fixing electronic equipment components or in-vehicle components using the adhesive tape described in claim 7, 8, or 9.

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