Adhesive, adhesive tape, and method for fixing electronic device components or vehicle-mounted components

Abstract

The present invention aims to provide a pressure-sensitive adhesive that can exhibit excellent adhesive strength while increasing the content of bio-derived carbon, a pressure-sensitive adhesive tape using the pressure-sensitive adhesive, and a method for fixing electronic device components or vehicle-mounted components. The present invention relates to a pressure-sensitive adhesive comprising a (meth)acrylic copolymer having a glass transition temperature of −20° C. or lower, and containing 48% by weight or more of structural units derived from monomer A represented by general formula (1) containing bio-derived carbon and / or monomer B represented by general formula (2) containing bio-derived carbon.

Description

[Technical Field]

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

[0002] Conventionally, adhesive tapes having an adhesive layer containing an adhesive have been widely used to fix components in electronic components, vehicles, houses, and building materials. Specifically, adhesive sheets have been used, for example, 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] Japanese Patent Application Laid-Open No. 2015-052050 [Patent Document 2] Japanese Patent Application Laid-Open No. 2015-021067 [Patent Document 3] Japanese Patent Application Laid-Open No. 2015-120876 Summary of the Invention [Problem to be solved by the invention]

[0004] In recent years, the depletion of petroleum resources and carbon dioxide emissions from the combustion of petroleum-derived products have become a major concern. Therefore, efforts have been made to conserve petroleum resources by replacing petroleum-derived materials with bio-derived materials, primarily in the fields of medicine and packaging materials. These efforts have spread to all fields, and the use of bio-derived materials is now being sought in the fields of adhesives and tapes.

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

[0006] The present invention aims to provide a pressure-sensitive adhesive that can exhibit excellent adhesive strength while increasing the content of bio-derived carbon, a pressure-sensitive adhesive tape using the pressure-sensitive 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 having a glass transition temperature of −20° C. or lower, and containing 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.

[0008] [ka]

[0009] In formula (1), R 1 represents H or CH3, R 2 Ha-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 extensive research, the present inventors have found that by selecting, as raw materials for the (meth)acrylic copolymer that constitutes the adhesive, monomer A (hereinafter also simply referred to as "monomer A") that contains bio-derived carbon and is represented by the above general formula (1) and / or monomer B (hereinafter also simply referred to as "monomer B") that contains bio-derived carbon and is represented by the above general formula (2), and adjusting the glass transition temperature of the (meth)acrylic copolymer to -20°C or lower, an adhesive that can exhibit excellent adhesive strength while having a high content of bio-derived carbon can be obtained.

[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 the monomers used as raw materials.

[0012] In the present invention, the monomer A and / or the monomer B are contained 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. When Monomer A and Monomer B, which contain plant-derived carbon, are used, they are resources 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, making it easy for adhesives composed of such monomers to exhibit their adhesive properties. Therefore, by using relatively large amounts of these monomers to increase the content of bio-derived carbon in the adhesive as a whole, and optionally combining them with other non-biologically derived monomers, adhesives with sufficient adhesive strength can be produced.

[0013] R in formula (1) 2 , and R in Equation (2) 3 The alkyl group contained in may be linear or branched, with linear groups being preferred since they provide high cohesive strength and 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 easily available, have a low glass transition temperature of their homopolymers, and are easily able to exhibit adhesive properties. Among them, it is more preferable for the monomer A to contain lauryl acrylate and / or lauryl methacrylate, and even more preferable for it to contain lauryl acrylate and lauryl methacrylate, because this results in a pressure-sensitive adhesive with excellent shear strength.

[0015] Specific examples of the monomer B include vinyl caprate, vinyl laurate, vinyl caprylate, and vinyl nonanoate. These monomers B may be used alone or in combination of two or more. Among them, vinyl caprate and / or vinyl laurate are particularly preferred because they are easily available, have a low glass transition temperature of their homopolymers, and are easily able to exhibit the adhesive function constituted by 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 biological carbon. From the viewpoint of further increasing adhesive strength, the (meth)acrylic copolymer preferably contains 55% by weight or more of the structural units derived from the monomer A and / or monomer B, more preferably 65% ​​by weight or more, even more preferably 75% by weight or more, and usually 100% by weight or less.

[0017] When the (meth)acrylic copolymer contains structural units derived from the monomer A, it is preferable that, from the viewpoint of further enhancing adhesive strength, structural units derived from lauryl acrylate and / or lauryl methacrylate account for 48% by weight or more of the structural units derived from the monomer A. 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 metallauryl 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.

[0018] The (meth)acrylic copolymer may contain structural units derived from other monomers than the monomers A and B. The other monomers are not particularly limited, and examples thereof include alkyl (meth)acrylates 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 one or two methyl groups in their linear main chain and (meth)acrylic acid, behenyl (meth)acrylate, and arachidyl (meth)acrylate. Other 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, (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.

[0019] In particular, from the viewpoint of improving adhesion to resins such as polypropylene and olefin-based resins such as acrylic, it is preferable that the (meth)acrylic copolymer 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 also be non-living monomers that do not contain carbon derived from living organisms. In theory, it is also possible for all of the monomers used as raw materials for the acrylic copolymer to be monomers containing carbon derived from living organisms. From the standpoint of the cost and productivity of the adhesive, it is possible to adopt a relatively inexpensive and easily available monomer containing carbon derived from living organisms, and combine the other monomers 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 pressure-sensitive adhesive to exhibit excellent adhesive strength. From the viewpoint of further enhancing 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 a preferred lower limit is 300,000 and a preferred upper limit is 2,000,000. When the weight-average molecular weight of the (meth)acrylic copolymer is within this range, the resulting pressure-sensitive adhesive can exhibit excellent adhesive strength. A more preferred lower limit of the weight-average molecular weight of the (meth)acrylic copolymer is 400,000, a more preferred upper limit is 1,800,000, an even more preferred lower limit is 500,000, and a particularly preferred lower limit is 1,000,000. In this specification, the weight average molecular weight means a molecular weight calculated as polystyrene by GPC measurement.

[0023] The (meth)acrylic copolymer can be obtained by subjecting a mixture of the raw material monomers to a radical reaction in the presence of a polymerization initiator. The radical reaction method is not particularly limited, and examples include living radical polymerization, free radical polymerization, etc. Living radical polymerization can provide a copolymer having a more uniform molecular weight and composition compared to free radical polymerization, can suppress the generation of low molecular weight components, etc., and increases the cohesive strength of the pressure-sensitive adhesive layer. The polymerization method is not particularly limited, and a conventionally known method can be used. Examples include solution polymerization (boiling point polymerization or constant temperature polymerization), emulsion polymerization, suspension polymerization, bulk polymerization, etc. Among these, 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 examples thereof include organic tellurium compounds, organic telluride compounds, etc. In addition to the organic tellurium polymerization initiator, an azo compound may also 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-based 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 resins, rosin ester resins, and hydrogenated rosin-based resins; terpene-based tackifiers such as terpene resins and terpene phenol resins; coumarone-indene resins, alicyclic saturated hydrocarbon resins, C5 petroleum resins, C9 petroleum resins, and C5-C9 copolymer petroleum resins. These tackifier resins may be used alone or in combination of two or more. Among these, biologically derived rosin-based tackifiers and terpene-based tackifiers are preferred. Examples of biologically derived tackifiers include rosin-based resins derived from natural resins such as pine resin, and terpene-based resins derived from plant essential oils.

[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 per 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 pressure-sensitive 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 of one embodiment of the present invention preferably has a bio-derived carbon content of 40% by weight or more. A bio-derived carbon content of 40% by weight or more is a measure of a "bio-based product." From the viewpoint of reducing the environmental burden of the adhesive tape as a whole, the bio-derived carbon content of the adhesive of one embodiment of the present invention is more preferably 60% by weight or more, and is usually 100% by weight or less. While biogenic carbon contains a certain percentage of the radioactive isotope C-14, petroleum-derived carbon contains almost no C-14. Therefore, the biogenic carbon content can be calculated by measuring the C-14 concentration in the adhesive tape. Specifically, this can be measured in accordance with 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 pressure-sensitive adhesive tape of one embodiment of the present invention may be a non-support tape having no substrate, a single-sided pressure-sensitive adhesive tape having a pressure-sensitive adhesive layer on one side of a substrate, or a double-sided pressure-sensitive adhesive tape having pressure-sensitive adhesive layers on both sides of a substrate.

[0032] The substrate is not particularly limited, and any conventionally known substrate can be used, but it is preferable to use a substrate of biological origin in order to increase the content of biologically derived carbon in the entire pressure-sensitive adhesive tape. Examples of the biological substrate include plant-derived polyesters (PES) such as polyethylene terephthalate (PET), polyethylene furanoate (PEF), polylactic acid (PLA), polytrimethylene terephthalate (PTT), polybutylene terephthalate (PBT), and polybutylene succinate (PBS), as well as 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 further 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] Furthermore, from the perspective of reducing the use of new petroleum resources and reducing carbon dioxide emissions to reduce the environmental impact, substrates made from recycled resources may be used. Examples of resource recycling methods include collecting waste materials such as packaging containers, home appliances, automobiles, construction materials, and food, as well as waste generated during manufacturing processes, and then cleaning, decontaminating, or decomposing the extracted materials by heating or fermentation to reuse them as raw materials. Examples of substrates made from recycled resources include films and nonwoven fabrics made from PET, PBT, PE, PP, PA, etc., which are made from recycled plastics that have been re-resinized. Furthermore, collected waste materials may be burned and used as thermal energy for the production of substrates and their raw materials. Oils and fats contained in the collected waste materials may be mixed with petroleum, fractionated, and purified, and then used as raw materials.

[0035] In another embodiment of the present invention, the substrate may be a foam substrate in order to improve compression properties. The foam substrate is preferably a foam substrate made of PE, PP, and / or PU, and from the viewpoint of achieving a high degree of both flexibility and strength, a foam substrate made of PE is more preferred. Examples of the constituents of the foam substrate made of PE include PE made from sugarcane.

[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 sugarcane and a foaming agent, foam the foaming agent when extruding the foamable resin composition into a sheet using an extruder, and crosslink the resulting polyolefin foam as needed.

[0037] The thickness of the foam substrate is not particularly limited, but a preferred lower limit is 50 μm and a preferred upper limit is 300 μm. When the foam substrate has a thickness within this range, it can exhibit high impact resistance and high flexibility that allows it to be adhered to the shape of the adherend.

[0038] The pressure-sensitive adhesive layer has a gel fraction of preferably 10% by weight or less, more preferably 20% by weight or less, and preferably 70% by weight or less, more preferably 50% by weight or less. 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, a pressure-sensitive adhesive tape is cut into a 50 mm x 100 mm flat rectangular shape to prepare a test piece. The test piece is immersed in ethyl acetate at 23°C for 24 hours, then removed from the ethyl acetate and dried at 110°C for 1 hour. The weight of the test piece after drying is measured, and the gel fraction is calculated using the following formula. Note that no release film to protect the pressure-sensitive adhesive layer is laminated on the test piece. Gel fraction (wt%) = 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 a preferred lower limit is 10 μm and a 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 can be produced by a conventionally known production method. For example, in the case of a double-sided pressure-sensitive adhesive tape, the following method can 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 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 separate from the above-mentioned release film is prepared, and a solution of adhesive B is applied to the release-treated surface of this release film. The solvent in the solution is then completely dried and removed to produce a laminate film in which adhesive layer B is formed on the surface of the release film. The obtained laminate film is overlaid on the back surface of a 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-mentioned laminate with a rubber roller or the like, a double-sided adhesive tape can be obtained which has adhesive layers on both sides of the substrate and in which the surfaces of the adhesive layers are covered with release films.

[0042] Alternatively, two sets of laminate films may be prepared in a similar manner, and these laminate films may be superimposed on each of both surfaces of a substrate with the adhesive layer of the laminate film facing the substrate to prepare 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 surfaces of the substrate and the surfaces of the adhesive layers covered with release films.

[0043] The use of the pressure-sensitive adhesive tape of one embodiment of the present invention is not particularly limited, but because of its excellent adhesive strength and heat resistance, it can be particularly suitably used for fixing electronic device components and vehicle-mounted components. Specifically, the pressure-sensitive adhesive tape of one embodiment of the present invention can be suitably used for adhesively fixing electronic device components in large portable electronic devices, adhesively fixing vehicle-mounted components (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 fixation to continue even when exposed to high temperatures. [Effects of the Invention]

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

[0046] The following examples will explain the present invention in more detail, 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 of acrylic acid with lauryl alcohol, which was prepared by hydrolyzing oils such as palm kernel oil and coconut oil, fractionating the resulting fatty acids, and then hydrogenating the lauric acid extracted from them.

[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 the esterification of methacrylic acid with n-decyl alcohol, which was prepared by hydrolyzing oils such as palm kernel oil and coconut oil, followed by fractional distillation of the resulting fatty acids, followed by hydrogen reduction of capric acid.

[0050] (4) Preparation of n-octyl acrylate containing bio-derived carbon n-Octyl acrylate was prepared by the esterification of acrylic acid with n-octyl alcohol, which was obtained by hydrolyzing oils such as palm kernel oil and coconut oil, followed by fractional distillation of the resulting fatty acids, followed by hydrogen reduction of caprylic acid.

[0051] (5) Preparation of isobornyl acrylate containing bio-derived carbon Isobornyl acrylate was prepared by reacting acrylic acid with camphene according to the method described in JP 2006-69944 A. Camphene was obtained by isomerizing α-pinene, which is obtained from pine resin and 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 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 the 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, followed by fractional distillation of the resulting fatty acids, followed by hydrogen reduction of the stearic acid.

[0055] <Non-biologically derived monomers> The following commercially available monomers were prepared as non-biologically derived monomers. (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 bio-derived 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 to a reaction vessel, and nitrogen was bubbled through. The reaction vessel was then heated while nitrogen was flowing in to initiate reflux. Subsequently, a polymerization initiator solution prepared by diluting 0.1 parts by weight of azobisisobutyronitrile 10 times with ethyl acetate was added to the reaction vessel, 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 two hours. After the dropwise addition, a polymerization initiator solution prepared by diluting 0.1 parts by weight of azobisisobutyronitrile 10 times with ethyl acetate was added again to the reaction vessel, and the polymerization reaction was carried out for four 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 resulting (meth)acrylic copolymer was diluted 50-fold 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 at a sample flow rate of 1 mL / min and a column temperature of 40°C. The polystyrene-equivalent molecular weight of the (meth)acrylic copolymer was measured, and the weight-average molecular weight was calculated. The weight-average molecular weight was 720,000.

[0061] (2) Manufacture of adhesive tapes To the resulting (meth)acrylic copolymer-containing solution, 3 parts by weight of crosslinker, 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 the (meth)acrylic copolymer to prepare a pressure-sensitive adhesive solution. This pressure-sensitive adhesive solution was applied to a 75 μm-thick release-treated PET film so that the thickness of the pressure-sensitive adhesive layer after drying would be 50 μm, and then dried at 110°C for 5 minutes. This pressure-sensitive adhesive layer was then layered on a 75 μm-thick release-treated PET film and aged at 40°C for 48 hours to obtain a pressure-sensitive adhesive tape (non-support type).

[0062] The release film on one side of the resulting adhesive tape was peeled off, and the tape was laminated to a 50 μm-thick PET film and cut into a 20 mm × 40 mm flat rectangle. The release film on the other side of the adhesive tape was then peeled off to prepare a test piece, and its weight was measured. The test piece was immersed in ethyl acetate at 23°C for 24 hours, then removed from the ethyl acetate and dried at 110°C for 1 hour. The weight of the dried test piece was measured, and the gel fraction was calculated using the following formula: The gel fraction was 38% by weight. 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) An adhesive tape was obtained in the same manner as in Example 1, except that the monomers of the (meth)acrylic copolymer and the tackifiers to be blended in the adhesive tape were as shown in Tables 1 to 4. In Example 21, a double-sided adhesive tape was produced in which adhesive layers of 25 μm thickness were formed on both sides of a substrate. The substrate was a 25 μm thick film of nylon 610 (CM2001, manufactured by Toray Industries, Inc.), a plant-derived polyamide resin.

[0064] In Example 22, a double-sided pressure-sensitive adhesive tape having a foam substrate and pressure-sensitive adhesive layers each having a thickness of 50 μm formed on both sides thereof was produced by the following method. The adhesive solution was applied to a 75 μm-thick release-treated PET film so that the adhesive layer would have a thickness of 50 μm after drying, and then dried at 110°C for 5 minutes to obtain adhesive layer A. This adhesive layer A was then overlaid on a 100 μm-thick PE foam substrate with an expansion ratio of 3, and pressed with a rubber roller or the like to produce a laminate in which adhesive layer A was formed on the surface of the release film. Next, a separate release film was prepared and coated on the film so that the adhesive layer would have a thickness of 50 μm after drying, and then dried at 110°C for 5 minutes to obtain adhesive layer B. This adhesive layer B was then bonded to the surface of the foam in the laminate opposite adhesive layer A, and similarly pressed with a rubber roller or the like. This was then 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 x 10mm double-sided adhesive tape was sandwiched between two SUS plates and pressed together with a 5kg weight for 10 seconds, 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 rate of 10mm / min, and the force (N) at which the tape peeled off was measured. The in-plane peel strength (Pa) was calculated using the following formula: Peeling force in the surface direction (Pa) = force when the tape is peeled off (N) ÷ tape area (m 2 ) 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 x 10mm double-sided adhesive tape was sandwiched between two SUS plates and pressed together with a 5kg weight for 10 seconds, then cured for 24 hours at 23°C and 50% humidity. The two SUS plates were then placed vertically on a jig, with one SUS plate secured to the lower fixture and the other secured to the upper fixture. The upper fixture was then pulled vertically at a pulling rate of 10mm / min, and the force (N) at which the tape peeled was measured. The shear peel strength (Pa) was calculated using the following formula: Shear direction peeling force (Pa) = force when tape is peeled (N) ÷ tape area (m 2 ) The 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 a pressure-sensitive adhesive that can exhibit excellent adhesive strength while increasing the content of biological carbon, a pressure-sensitive adhesive tape using the pressure-sensitive adhesive, and a method for fixing electronic device components or vehicle-mounted components.

Claims

1. A pressure-sensitive adhesive comprising a (meth)acrylic copolymer having a glass transition temperature of -20°C or lower and a weight-average molecular weight of 400,000 or higher, and a tackifier of biological origin, The (meth)acrylic copolymer contains a structural unit derived from a monomer A containing carbon of biological origin, and may or may not contain a structural unit derived from a monomer B containing carbon of biological origin and represented by the following general formula (2), and the total content of the structural units derived from the monomer A and the structural units derived from the 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 biologically-derived tackifier is a rosin-based tackifier and / or a terpene-based tackifier, The content of the biologically derived tackifier is 10 to 50 parts by weight based on 100 parts by weight of the (meth)acrylic copolymer. Adhesive (however, (meth)acrylate group and C ６ ~C ２０ (Excluding adhesives containing crosslinking monomers containing olefin groups, adhesives for polarizing plates, and microsphere adhesives). 【Chemistry 1】 In formula (2), R ３ is -C(=O)C ｍ H ２ｍ＋１ and m represents an integer of 7 to 13. R ３ The carbon in it is of biological origin.

2. The pressure-sensitive adhesive according to claim 1, further comprising an isocyanate-based crosslinking agent, an aziridine-based crosslinking agent, an epoxy-based crosslinking agent, or a metal chelate-based crosslinking agent.

3. The pressure-sensitive adhesive according to claim 1 , wherein the monomer A is lauryl acrylate and / or lauryl methacrylate.

4. The pressure-sensitive adhesive according to claim 1 , wherein the monomer B is vinyl caprate and / or vinyl laurate.

5. 5. The pressure-sensitive adhesive according to claim 1, wherein the (meth)acrylic copolymer contains 48% by weight or more of structural units derived from lauryl acrylate and / or lauryl methacrylate among structural units derived from the monomer A.

6. The pressure-sensitive adhesive according to claim 1, 2, 3, 4 or 5, wherein, in the (meth)acrylic copolymer, among the structural units derived from the monomer A, structural units derived from lauryl acrylate account for 10 to 90% by weight and structural units derived from lauryl methacrylate account for 10 to 90% by weight.

7. 7. The pressure-sensitive adhesive according to claim 1, wherein the (meth)acrylic copolymer has a structural unit derived from an alkyl ester (meth)acrylate having an alkyl group having 16 to 24 carbon atoms.

8. The adhesive according to claim 1, 2, 3, 4, 5, 6 or 7, wherein the content of carbon derived from living organisms is 71% by weight or more.

9. 9. The pressure-sensitive adhesive according to claim 1, wherein the (meth)acrylic copolymer has a weight-average molecular weight of 780,000 or less.

10. An adhesive tape having an adhesive layer containing the adhesive according to claim 1 , 2, 3, 4, 5, 6, 7, 8 or 9.

11. The pressure-sensitive adhesive tape according to claim 10, further comprising a substrate, the substrate being a film made of polyester or polyamide.

12. The adhesive tape of claim 10, further comprising a foam substrate.

13. The adhesive tape according to claim 10, 11 or 12, which is used for fixing electronic equipment parts or vehicle-mounted parts.

14. A method for fixing electronic equipment components or vehicle-mounted components, comprising using the adhesive tape according to claim 10, 11 or 12.

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