Adhesive composition, adhesive tape, method for fixing electronic device component or vehicle-mounted component, and manufacturing method

Abstract

The present invention relates to an adhesive composition, an adhesive tape, a fixing method of an electronic device member or a vehicle-mounted member, and a manufacturing method of an electronic device member or a vehicle-mounted member. An object of the present invention is to provide an adhesive composition capable of exerting excellent adhesive force with respect to either of a smooth surface and a rough surface. In addition, an object of the present invention is to provide an adhesive tape having an adhesive layer containing the adhesive composition, and a fixing method and a manufacturing method of an electronic device member or a vehicle-mounted member using the adhesive tape. The present invention includes an adhesive composition containing an acrylic copolymer having a structural unit derived from n-heptyl (meth)acrylate.

Description

[0001] This application is a divisional application of the parent application with the filing date of December 17, 2020, the international application number of PCT / JP2020 / 047202, the entering Chinese national phase application number of 202080079568.0, and the invention name of Adhesive composition, method for fixing electronic device component or vehicle-mounted component, and method for manufacturing electronic device component or vehicle-mounted component. TECHNICAL FIELD

[0002] The present application relates to an adhesive composition capable of exerting excellent adhesive force with respect to either one of a smooth surface and a rough surface. In addition, the present application relates to an adhesive tape having an adhesive layer containing the adhesive composition, and a method for fixing and a method for manufacturing an electronic device component or a vehicle-mounted component using the adhesive tape. BACKGROUND

[0003] In the past, when fixing components in electronic components, vehicles, houses, and building materials, an adhesive tape having an adhesive layer containing an adhesive has been widely used (for example, Patent Documents 1 to 3). Specifically, for example, in order to bond a cover plate for protecting the surface of a portable electronic device to a touch panel module or a display panel module, or to bond a touch panel module to a display panel module, an adhesive tape has been used.

[0004] PRIOR ART DOCUMENTS

[0005] PATENT DOCUMENTS

[0006] Patent Document 1: Japanese Patent Application Publication No. 2015-052050

[0007] Patent Document 2: Japanese Patent Application Publication No. 2015-021067

[0008] Patent Document 3: Japanese Patent Application Publication No. 2015-120876 SUMMARY

[0009] PROBLEMS TO BE SOLVED BY THE INVENTION

[0010] As an adhesive having excellent adhesive force, an acrylic adhesive containing an acrylic copolymer has been widely used.

[0011] As the acrylic monomer constituting the acrylic copolymer, for example, an alkyl (meth)acrylate such as butyl (meth)acrylate or 2-ethylhexyl (meth)acrylate can be used. Among them, by using butyl (meth)acrylate as the main component, an adhesive having excellent adhesion can be obtained. However, such an adhesive is excellent in adhesion to a smooth surface, but has low followability to a concave-convex surface and insufficient adhesion to a rough surface. On the other hand, by using 2-ethylhexyl (meth)acrylate as the main component, the followability of the adhesive to a concave-convex surface can be improved. However, such an adhesive originally has insufficient adhesion to an adherend, and it is difficult to obtain excellent adhesion to either of a smooth surface and a rough surface.

[0012] An object of the present application is to provide an adhesive composition capable of exhibiting excellent adhesion to either of a smooth surface and a rough surface (particularly, more excellent adhesion to a rough surface than butyl (meth)acrylate-based and 2-ethylhexyl (meth)acrylate-based adhesives). In addition, an object of the present application is to provide an adhesive tape having an adhesive layer containing the adhesive composition, and a method for fixing an electronic device member or a vehicle-mounted member using the adhesive tape.

[0013] Means for solving the problem

[0014] The present application is an adhesive composition containing an acrylic copolymer having a structural unit derived from n-heptyl (meth)acrylate.

[0015] Note that in the present specification, (meth)acrylate means acrylate or methacrylate, and (meth)acrylic acid means acrylic acid or methacrylic acid. The acrylic copolymer can be a methacrylic copolymer.

[0016] The present application will be described in detail below.

[0017] The present inventors have found that, for an adhesive composition containing an acrylic copolymer, among various acrylic monomers constituting the acrylic copolymer, particularly by using n-heptyl (meth)acrylate, an adhesive composition capable of exhibiting excellent adhesion to either of a smooth surface and a rough surface can be obtained, and thus the present application has been accomplished.

[0018] The adhesive composition of the present application contains an acrylic copolymer having a structural unit derived from n-heptyl (meth)acrylate. Thus, the adhesive composition of the present application can exhibit excellent adhesion to either of a smooth surface and a rough surface.

[0019] The reason is not certain, but it can be cited that the n-heptyl group of n-heptyl (meth)acrylate is linear, and thus the cohesion of the adhesive layer containing the adhesive composition of the present application is increased, and the peeling resistance is made greater by the acrylic copolymer having the structural unit derived from n-heptyl (meth)acrylate. In addition, it can be cited that the glass transition temperature (Tg) of the acrylic copolymer is lowered, and the storage modulus of the adhesive layer containing the adhesive composition of the present application at ordinary temperature is lowered, and the followability of the adhesive layer to irregularities is improved by the acrylic copolymer having the structural unit derived from n-heptyl (meth)acrylate. In addition, it can be cited that a hydrocarbon having an odd number of carbon atoms has a tendency that the packing of molecules with each other is not easily performed, and the melting point is lowered, as compared to a hydrocarbon having an even number of carbon atoms. The n-heptyl group which is linear and has an odd number of carbon atoms also does not easily pack in the same manner, and thus the side chain does not easily pack, and the softness is easily exhibited, and the followability of the adhesive layer containing the adhesive composition of the present application to irregularities is improved by the acrylic copolymer having the structural unit derived from n-heptyl (meth)acrylate.

[0020] The n-heptyl (meth)acrylate in the structural unit derived from n-heptyl (meth)acrylate can be formed only from a material derived from petroleum, but preferably contains a material derived from a living organism.

[0021] In recent years, the depletion of petroleum resources, and the emission of carbon dioxide resulting from the combustion of products derived from petroleum are regarded as problems. Therefore, attempts are being made to conserve petroleum resources by using a material derived from a living organism instead of a material derived from petroleum.

[0022] The n-heptyl (meth)acrylate in the structural unit derived from n-heptyl (meth)acrylate is preferably a material derived from a living organism from the viewpoint of conserving petroleum resources. In addition, if the n-heptyl (meth)acrylate in the structural unit derived from n-heptyl (meth)acrylate is a material derived from a living organism, it is considered that even if it is combusted, it does not increase the carbon dioxide in the atmosphere as a whole, because the material derived from a living organism is originally produced by taking in carbon dioxide in the atmosphere, and thus it is preferable from the viewpoint of reducing the amount of emission of carbon dioxide.

[0023] In the case where the n-heptyl (meth)acrylate in the structural unit derived from n-heptyl (meth)acrylate is a material derived from a living organism, the n-heptyl (meth)acrylate is preferably synthesized by esterification of n-heptanol as a material derived from a living organism with (meth)acrylic acid.

[0024] The n-heptanol as a material derived from a living organism can be obtained inexpensively and easily, for example, by using a material collected from plants and animals, etc. (for example, ricinoleic acid derived from castor oil, etc.) as a raw material, and subjecting it to cleavage.

[0025] The content of the structural unit derived from n-heptyl (meth)acrylate in the above-described acrylic copolymer is not particularly limited, but the lower limit of the preferable range is 25% by weight.

[0026] If the content of the structural unit derived from n-heptyl (meth)acrylate is 25% by weight or more, the adhesion of the adhesive composition to a smooth surface and a rough surface is further improved. In addition, if the content of the structural unit derived from n-heptyl (meth)acrylate is 25% by weight or more, the content of the biologically derived material in the entire adhesive composition can be increased in the case where n-heptyl (meth)acrylate in the structural unit derived from n-heptyl (meth)acrylate contains a biologically derived material. The more preferable lower limit of the content of the structural unit derived from n-heptyl (meth)acrylate is 48% by weight, the further preferable lower limit is 60% by weight, the further more preferable lower limit is 70% by weight, and the still further preferable lower limit is 80% by weight.

[0027] The upper limit of the content of the structural unit derived from n-heptyl (meth)acrylate is not particularly limited, and can be 100% by weight, but since the above-described acrylic copolymer preferably also has a structural unit derived from a monomer having a cross-linkable functional group or the like, the preferable upper limit is 99% by weight, and the more preferable upper limit is 97% by weight.

[0028] The content of the structural unit derived from n-heptyl (meth)acrylate in the above-described acrylic copolymer can be determined by performing mass spectrometric analysis of the above-described acrylic copolymer and 1 H-NMR measurement, and calculating from the ratio of the integral intensity of the peak of the hydrogen derived from n-heptyl (meth)acrylate.

[0029] The above-described acrylic copolymer preferably also has a structural unit derived from a monomer having a cross-linkable functional group.

[0030] By having the above-described acrylic copolymer have a structural unit derived from a monomer having a cross-linkable functional group, the cohesion of the adhesive layer containing the adhesive composition is increased, and the adhesion to a smooth surface and a rough surface is further improved.

[0031] The above-described monomer having a cross-linkable functional group is not particularly limited, and examples thereof include a monomer having a hydroxyl group, a monomer having a carboxyl group, a monomer having a glycidyl group, a monomer having an amide group, a monomer having a nitrile group, and the like. Among these, from the aspect that the adjustment of the gel fraction of the adhesive layer containing the adhesive composition is easy, a monomer having a hydroxyl group and a monomer having a carboxyl group are preferable, and a monomer having a hydroxyl group is more preferable.

[0032] As the monomer having a hydroxyl group, for example, there can be mentioned (meth)acrylic acid 4-hydroxybutyl ester, (meth)acrylic acid 2-hydroxyethyl ester and the like. As the monomer having a carboxyl group, for example, there can be mentioned (meth)acrylic acid and the like. As the monomer having a glycidyl group, for example, there can be mentioned (meth)acrylic acid glycidyl ester and the like. As the monomer having an amide group, for example, there can be mentioned hydroxyethyl (meth)acrylamide, isopropyl (meth)acrylamide, dimethylaminopropyl (meth)acrylamide and the like. As the monomer having a nitrile group, for example, there can be mentioned (meth)acrylonitrile and the like.

[0033] These monomers having a cross-linkable functional group can be used alone or in combination of two or more.

[0034] The content of the structural unit derived from the monomer having a cross-linkable functional group in the above-described acrylic copolymer is not particularly limited, but the lower limit of the preferable range is 0.01% by weight, and the upper limit of the preferable range is 20% by weight. If the content of the structural unit derived from the monomer having a cross-linkable functional group is within the above-described range, the adhesion of the adhesive composition to a smooth surface and a rough surface is further improved. The more preferable lower limit of the content of the structural unit derived from the monomer having a cross-linkable functional group is 0.1% by weight, the more preferable upper limit is 10% by weight, the further more preferable lower limit is 0.5% by weight, and the further more preferable upper limit is 5% by weight.

[0035] The content of the structural unit derived from the monomer having a cross-linkable functional group in the above-described acrylic copolymer can be determined by performing mass spectrometric analysis of the above-described acrylic copolymer and 1 The content of the structural unit derived from each monomer was calculated from the ratio of the integral intensity of the peak of hydrogen derived from each monomer by H-NMR measurement.

[0036] For the adhesive composition of the present application, the present inventors and others further studied the retention force which does not peel even when a stress is applied (particularly, the shear retention force which does not peel even when a stress in the shear direction is applied), and the resilience resistance which does not peel even when a stress is generated due to deformation of the adherend. Among them, by adjusting the content of the structural unit derived from the monomer having a cross-linkable functional group (particularly, the monomer having a hydroxyl group), the cohesion of the adhesive layer containing the adhesive composition is increased, and the retention force and the resilience resistance are improved, but it was found that the improvement of the retention force and the resilience resistance is insufficient if only the content of the above-described structural unit is adjusted.

[0037] In this regard, the present inventors have found that by setting a value X represented by the following formula (1) with respect to the amount of hydroxyl groups present in each molecular chain of the above-described acrylic copolymer to a specific range, an excellent holding power and a resistance to springback can be obtained. That is, the value X represented by the following formula (1) of the above-described acrylic copolymer is preferably 2 or greater and 50 or less.

[0038] [Mathematical Formula 1]

[0039]

[0040] In formula (1), Mw polymer represents the weight average molecular weight of the acrylic copolymer, W OH represents the content (parts by weight) of the structural unit derived from the monomer having a hydroxyl group in the acrylic copolymer, W total represents the content (parts by weight) of the total monomers constituting the acrylic copolymer, M OH represents the molecular weight of the monomer having a hydroxyl group, and n represents the hydroxyl value of the monomer having a hydroxyl group. In the case where there are structural units derived from two or more kinds of monomers having a hydroxyl group, the value X is obtained for each monomer, and they are added to calculate the value X.

[0041] The above-described value X is a value with respect to the amount of hydroxyl groups present in each molecular chain of the above-described acrylic copolymer. By making the above-described value X 2 or greater, the number of crosslinkable functional groups of each molecular chain of the above-described acrylic copolymer increases, and it is easy to produce an adhesive composition having an excellent holding power. By making the above-described value X 50 or less, it is easy to adjust the gel fraction and the crosslinking degree of the adhesive layer containing the adhesive composition. As a result, it is easy to produce an adhesive composition having an excellent holding power and a resistance to springback. A more preferable lower limit of the above-described value X is 5, a more preferable upper limit is 30, a further more preferable upper limit is 26.9, and a still further more preferable upper limit is 20.

[0042] The method of adjusting the above-described value X is not particularly limited, and methods such as a method of selecting the kind of the above-described monomer having a hydroxyl group or adjusting the content thereof, a method of adjusting the weight average molecular weight of the above-described acrylic copolymer, and the like can be given.

[0043] More specifically, as a method of increasing the above-described value X, for example, a method of increasing the weight average molecular weight of the above-described acrylic copolymer, a method of increasing the content of the above-described monomer having a hydroxyl group, a method of decreasing the molecular weight of the above-described monomer having a hydroxyl group, a method of increasing the hydroxyl value of the above-described monomer having a hydroxyl group, and the like can be given. As a method of decreasing the above-described value X, for example, a method of decreasing the weight average molecular weight of the above-described acrylic copolymer, a method of decreasing the content of the above-described monomer having a hydroxyl group, a method of increasing the molecular weight of the above-described monomer having a hydroxyl group, a method of decreasing the hydroxyl value of the above-described monomer having a hydroxyl group, and the like can be given.

[0044] The above-described acrylic copolymer can have a structural unit derived from another monomer in addition to the above-described structural unit derived from n-heptyl (meth)acrylate and the above-described structural unit derived from a monomer having a crosslinkable functional group.

[0045] The above-described other monomer is not particularly limited, and for example, (meth)acrylic acid alkyl esters can be given.

[0046] As the above-described (meth)acrylic acid alkyl ester, for example, methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, n-butyl (meth)acrylate, t-butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, n-octyl (meth)acrylate, iso-octyl (meth)acrylate, n-nonyl (meth)acrylate, iso-nonyl (meth)acrylate, myristyl (meth)acrylate, cetyl (meth)acrylate, stearyl (meth)acrylate, an ester of 5,7,7-trimethyl-2-(1,3,3-trimethylbutyl) octanol-1 and (meth)acrylic acid, an ester of an alcohol having a total carbon number of 18 of 1 or 2 methyl groups on a linear main chain and (meth)acrylic acid, behenyl (meth)acrylate, arachidyl (meth)acrylate, and the like can be given. These (meth)acrylic acid alkyl esters can be used alone or in combination of two or more.

[0047] In addition, as the above-described other monomer, for example, (meth)acrylic acid cyclohexyl ester, (meth)acrylic acid isobornyl ester, (meth)acrylic acid benzyl ester, (meth)acrylic acid 2-butoxyethyl ester, (meth)acrylic acid 2-phenoxyethyl ester, (meth)acrylic acid tetrahydrofurfuryl ester, polypropylene glycol mono(meth)acrylate, and the like can be given. Furthermore, as the above-described other monomer, for example, vinyl acetate and the like vinyl carboxylate, styrene and the like various monomers used for general acrylic polymers can be used. These other monomers can be used alone or in combination of two or more.

[0048] Among them, as the above-described other monomer, at least one monomer selected from (meth)acrylic acid tetrahydrofurfuryl ester, (meth)acrylic acid isobornyl ester, (meth)acrylic acid cyclohexyl ester, (meth)acrylic acid t-butyl ester, (meth)acrylic acid benzyl ester, and (meth)acrylic acid 2-phenoxyethyl ester is preferred. By having a structural unit derived from these monomers, the adhesion of the adhesive composition to a resin adherend containing polycarbonate or the like is improved. In addition, by having a structural unit derived from these monomers, the adhesion of the adhesive composition to smooth and rough surfaces is further improved. Among them, since a material derived from a living organism is present, and the content of the carbon derived from a living organism described later is easily increased, at least one monomer selected from (meth)acrylic acid tetrahydrofurfuryl ester and (meth)acrylic acid isobornyl ester is more preferred.

[0049] The content of the structural unit derived from the at least one monomer selected from the group consisting of tetrahydrofurfuryl (meth)acrylate and isobornyl (meth)acrylate in the above-described acrylic copolymer is not particularly limited, but a preferable lower limit is 1% by weight, and a preferable upper limit is 40% by weight. If the content of the above-described structural unit is 1% by weight or more, the adhesion of the adhesive composition to a resin adherend such as polycarbonate is further improved. In addition, if the content of the above-described structural unit is 1% by weight or more, the adhesion of the adhesive composition to smooth surfaces and rough surfaces is further improved. If the content of the above-described structural unit is 40% by weight or less, the glass transition temperature (Tg) of the above-described acrylic copolymer is lowered, the followability of the adhesive layer containing the adhesive composition to unevenness is improved, and thus the adhesion to rough surfaces is further improved, in particular. A more preferable lower limit of the content of the structural unit derived from the at least one monomer selected from the group consisting of tetrahydrofurfuryl (meth)acrylate and isobornyl (meth)acrylate is 5% by weight, and a further preferable lower limit is 10% by weight. A more preferable upper limit of the content of the structural unit derived from the at least one monomer selected from the group consisting of tetrahydrofurfuryl (meth)acrylate and isobornyl (meth)acrylate is 30% by weight, a further preferable upper limit is 25% by weight, and a further more preferable upper limit is 20% by weight.

[0050] The above-described acrylic copolymer can have a structural unit derived from a (meth)acrylate having an alkyl group having a carbon number of 8 or more.

[0051] The above-described (meth)acrylate having an alkyl group having a carbon number of 8 or more is not particularly limited, and examples of the above-described (meth)acrylate include 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, an ester of 5,7,7-trimethyl-2-(1,3,3-trimethylbutyl) octanol-1 and (meth)acrylic acid, an ester of an alcohol having a total carbon number of 18 of 1 or 2 methyl groups on a linear main chain and (meth)acrylic acid, behenyl (meth)acrylate, arachidyl (meth)acrylate, and the like.

[0052] The content of the structural unit derived from the (meth)acrylate ester having an alkyl group having 8 or more carbon atoms in the above-described acrylic copolymer is not particularly limited, but the upper limit is preferably 50% by weight. If the content of the structural unit derived from the (meth)acrylate ester having an alkyl group having 8 or more carbon atoms is 50% by weight or less, the adhesion of the adhesive composition to a smooth surface and a rough surface is further improved. The more preferable upper limit of the content of the structural unit derived from the (meth)acrylate ester having an alkyl group having 8 or more carbon atoms is 48.5% by weight, the further preferable upper limit is 40% by weight, and the further more preferable upper limit is 30% by weight.

[0053] The lower limit of the content of the structural unit derived from the (meth)acrylate ester having an alkyl group having 8 or more carbon atoms is not particularly limited, and can be 0% by weight. In the case where the structural unit derived from the (meth)acrylate ester having an alkyl group having 8 or more carbon atoms is contained, the preferable lower limit of the content thereof is 1% by weight, and the more preferable lower limit is 5% by weight.

[0054] The content of the structural unit derived from at least one monomer selected from the group consisting of tetrahydrofurfuryl (meth)acrylate and isobornyl (meth)acrylate in the above-described acrylic copolymer can be calculated by performing mass spectrometric analysis of the above-described acrylic copolymer and 1 H-NMR measurement, and calculated from the ratio of the integral intensity of the peak derived from the hydrogen of each monomer. The content of the structural unit derived from the (meth)acrylate ester having an alkyl group having 8 or more carbon atoms in the above-described acrylic copolymer can also be calculated by performing mass spectrometric analysis of the above-described acrylic copolymer and 1 H-NMR measurement, and calculated from the ratio of the integral intensity of the peak derived from the hydrogen of each monomer.

[0055] The above-described monomer having a crosslinkable functional group and the above-described other monomer preferably contain a material derived from a living organism, but can also be formed only of a material derived from petroleum.

[0056] In principle, all of the acrylic monomers constituting the above-described acrylic copolymer can be set to monomers containing a material derived from a living organism. From the viewpoint of the cost and productivity of the adhesive composition, a monomer containing a material derived from a living organism, which is relatively inexpensive and easy to obtain, can be used in combination with a monomer formed only of a material derived from petroleum.

[0057] The glass transition temperature (Tg) of the above-described acrylic copolymer is not particularly limited, but is preferably -20°C or lower. If the glass transition temperature (Tg) of the above-described acrylic copolymer is -20°C or lower, the adhesion of the adhesive layer containing the adhesive composition to the concave-convex surface is improved, and thus the adhesion to the rough surface is particularly improved. The glass transition temperature (Tg) of the above-described acrylic copolymer is more preferably -30°C or lower, further preferably -40°C or lower, and further more preferably -50°C or lower. The lower limit of the glass transition temperature (Tg) of the above-described acrylic copolymer is not particularly limited, and is usually -90°C or higher, and preferably -80°C or higher.

[0058] The glass transition temperature (Tg) of the above-described acrylic copolymer can be obtained, for example, by differential scanning calorimetry.

[0059] The weight average molecular weight of the above-described acrylic copolymer is not particularly limited, but the lower limit thereof is preferably 200,000, and the upper limit thereof is preferably 2,000,000. If the weight average molecular weight of the above-described acrylic copolymer is within the above-described range, the adhesion of the adhesive composition to the smooth surface and the rough surface is further improved. The more preferable lower limit of the weight average molecular weight of the above-described acrylic copolymer is 400,000, the more preferable upper limit thereof is 1,800,000, the further preferable lower limit thereof is 500,000, and the further preferable upper limit thereof is 1,500,000.

[0060] Note that the weight average molecular weight refers to the weight average molecular weight converted to standard polystyrene as measured by GPC (Gel Permeation Chromatography). Specifically, the acrylic copolymer is diluted 50 times with tetrahydrofuran (THF), and the obtained diluted solution is filtered with a filter (material: polytetrafluoroethylene, pore size: 0.2 μm) to prepare a measurement sample. Next, the measurement sample is supplied to a gel permeation chromatograph (manufactured by Waters Corporation, trade name "2690 Separations Model" or the like), and GPC measurement is performed under the conditions of a sample flow rate of 1 mL / min and a column temperature of 40°C. The polystyrene-converted molecular weight of the acrylic copolymer is measured, and the value is used as the weight average molecular weight of the acrylic copolymer.

[0061] The above-described acrylic copolymer can be obtained by subjecting a monomer mixture serving as a raw material to radical reaction in the presence of a polymerization initiator.

[0062] The manner of the radical reaction is not particularly limited, and examples include active radical polymerization, radical polymerization, and the like. According to the active radical polymerization, a copolymer having a more uniform molecular weight and composition can be obtained, and the generation of low molecular weight components and the like can be suppressed, so that the cohesion of the adhesive layer containing the adhesive composition is increased, and the adhesion to smooth surfaces and rough surfaces is improved.

[0063] The polymerization method is not particularly limited, and a publicly known method can be used. As the polymerization method, for example, solution polymerization (boiling point polymerization or constant temperature polymerization), UV polymerization, emulsion polymerization, suspension polymerization, bulk polymerization, and the like can be given. Among them, from the aspect of further improving the adhesion of the adhesive composition to smooth surfaces and rough surfaces, solution polymerization and UV polymerization are preferred. Furthermore, from the aspect of being able to easily mix a tackifying resin to the obtained acrylic copolymer, and further improving the adhesion of the adhesive composition, solution polymerization is more preferred.

[0064] In the case where solution polymerization is used as the polymerization method, as the reaction solvent, for example, ethyl acetate, toluene, methyl ethyl ketone, dimethyl sulfoxide, ethanol, acetone, diethyl ether, and the like can be given. These reaction solvents can be used alone, or two or more kinds can be used in combination.

[0065] The above-mentioned polymerization initiator is not particularly limited, and examples include organic peroxides, azo compounds, and the like. As the above-mentioned organic peroxides, for example, 1,1-bis(tert-hexylperoxy)-3,3,5-trimethylcyclohexane, tert-hexyl peroxy pivalate, tert-butyl peroxy pivalate, 2,5-dimethyl-2,5-bis(2-ethylhexanoylperoxy)hexane, tert-hexyl peroxy-2-ethylhexanoate, tert-butyl peroxy-2-ethylhexanoate, tert-butyl peroxy isobutyrate, tert-butyl peroxy-3,5,5-trimethylhexanoate, tert-butyl peroxy laurate, and the like can be given. As the above-mentioned azo compounds, for example, azobis isobutyronitrile, azobis cyclohexanecarbonitrile, and the like can be given. These polymerization initiators can be used alone, or two or more kinds can be used in combination.

[0066] In addition, in the case of active radical polymerization, as the above-mentioned polymerization initiator, for example, an organic tellurium polymerization initiator can be given. The above-mentioned organic tellurium polymerization initiator is not particularly limited if it is a general organic tellurium polymerization initiator used for active radical polymerization, and examples include organic tellurium compounds, organotelluride compounds. Note that, in active radical polymerization, in addition to the above-mentioned organic tellurium polymerization initiator, an azo compound can also be used as the above-mentioned polymerization initiator for the purpose of promoting the polymerization rate.

[0067] The adhesive composition of the present application preferably does not contain a surfactant. By not containing a surfactant, the adhesion of the adhesive composition to smooth surfaces and rough surfaces is further improved.

[0068] In order to make the adhesive composition of the present application not contain the above-mentioned surfactant, it is preferable that the above-mentioned surfactant is not used in obtaining the above-mentioned acrylic copolymer. For this purpose, for example, as the polymerization method in obtaining the above-mentioned acrylic copolymer, solution polymerization, UV polymerization or the like can be employed.

[0069] Note that, by the above-mentioned adhesive composition of the present application not containing the above-mentioned surfactant is meant that the content of the above-mentioned surfactant in the adhesive composition of the present application is 3% by weight or less, preferably 1% by weight or less.

[0070] The content of the above-mentioned surfactant can be obtained, for example, by measuring the adhesive composition using liquid chromatograph mass spectrometer (for example, NEXCERA manufactured by Shimadzu Corporation, Exactive manufactured by Thermo Fisher Scientific Inc. or the like). More specifically, an ethyl acetate solution of the adhesive composition is filtered with a filter (material: polytetrafluoroethylene, pore size: 0.2 μm). About 10 μL of the obtained filtrate is injected into the liquid chromatograph mass spectrometer and analyzed under the following conditions. From the area ratio occupied by the peak corresponding to the above-mentioned surfactant in the adhesive composition, the content of the above-mentioned surfactant can be obtained. Note that, preferably, for each surfactant species, a sample in which the content of the surfactant in the adhesive composition is known is prepared, a calibration curve showing the relationship between the content of the surfactant and the peak area ratio is prepared, and the analysis is performed.

[0071] Column: Hypersil GOLD (2.1 x 150 mm) manufactured by Thermo Fisher Scientific Inc.

[0072] Mobile phase: acetonitrile

[0073] Column temperature: 40°C

[0074] Flow rate: 1.0 mL / min

[0075] Ionization method: ESI

[0076] Capillary temperature: 350°C

[0077] From the viewpoint of being able to moderately adjust the gel fraction, it is preferable that the adhesive composition of the present application further contains a crosslinking agent.

[0078] The above-mentioned crosslinking agent is not particularly limited, and for example, isocyanate-based crosslinking agents, aziridine-based crosslinking agents, epoxy-based crosslinking agents, metal chelate-type crosslinking agents and the like can be mentioned. Among these, from the aspect that the adhesion of the adhesive composition to the adherend is excellent, an isocyanate-based crosslinking agent is preferable.

[0079] The content of the crosslinking agent in the adhesive composition of the present application is not particularly limited, but a preferable lower limit is 0.05 parts by weight and a preferable upper limit is 7 parts by weight, relative to 100 parts by weight of the acrylic copolymer. If the content of the crosslinking agent is within the above range, the gel fraction of the adhesive layer containing the adhesive composition is moderately adjusted, and the adhesion to smooth and rough surfaces is further improved. A more preferable lower limit of the content of the crosslinking agent is 0.1 parts by weight, and a more preferable upper limit is 5 parts by weight.

[0080] Note that the content of the crosslinking agent refers to the amount of the solid component of the crosslinking agent.

[0081] The adhesive composition of the present application preferably further contains a tackifying resin. By containing a tackifying resin, the adhesion of the adhesive composition to smooth and rough surfaces is further improved.

[0082] The tackifying resin is not particularly limited, and examples include rosin ester tackifying resins, terpene tackifying resins, coumarone-indene tackifying resins, alicyclic saturated hydrocarbon tackifying resins, C5 petroleum tackifying resins, C9 petroleum tackifying resins, C5-C9 copolymer petroleum tackifying resins, and the like. These tackifying resins can be used alone or in combination of two or more. Among them, at least one selected from rosin ester tackifying resins and terpene tackifying resins is preferable.

[0083] As the rosin ester tackifying resin, for example, polymerized rosin ester tackifying resins, hydrogenated rosin ester tackifying resins, and the like can be given. As the terpene tackifying resin, for example, terpene tackifying resins, terpene phenol tackifying resins, and the like can be given.

[0084] The rosin ester tackifying resin and the terpene tackifying resin are preferably derived from a living organism. As the rosin ester tackifying resin derived from a living organism, for example, rosin ester tackifying resins derived from natural resins such as pine resin can be given. As the terpene tackifying resin derived from a living organism, for example, terpene tackifying resins derived from essential oils of plants and the like can be given.

[0085] The content of the tackifying resin in the adhesive composition of the present application is not particularly limited, but a preferable lower limit is 10 parts by weight and a preferable upper limit is 60 parts by weight, relative to 100 parts by weight of the acrylic copolymer. If the content of the tackifying resin is within the above range, the adhesion of the adhesive composition to smooth and rough surfaces is further improved. A more preferable lower limit of the content of the tackifying resin is 15 parts by weight, a more preferable upper limit is 50 parts by weight, and a further preferable upper limit is 35 parts by weight.

[0086] The adhesive composition of the present application can contain, as needed, additives such as silane coupling agents, plasticizers, softening agents, fillers, pigments, dyes, and the like.

[0087] The content of the biogenic carbon in the adhesive composition of the present application is preferably 10% by weight or more. The content of the biogenic carbon of 10% by weight or more is a criterion for "bio-based product". If the content of the biogenic carbon is 10% by weight or more, it is preferable from the viewpoint of saving petroleum resources and reducing the amount of carbon dioxide emissions. The more preferable lower limit of the content of the biogenic carbon is 40% by weight or more, and the further preferable lower limit is 60% by weight. The upper limit of the content of the biogenic carbon is not particularly limited and can be 100% by weight.

[0088] Note that the biogenic carbon contains a certain proportion of a radioisotope (C-14), and, in contrast, the carbon derived from petroleum contains almost no C-14. Therefore, the content of the biogenic carbon can be calculated by measuring the concentration of C-14 contained in the adhesive composition. Specifically, it can be measured in accordance with the standard used in many bio-plastics industries, ASTM D6866-20.

[0089] In addition, an adhesive tape having an adhesive layer containing the adhesive composition of the present application is also one of the present application.

[0090] The gel fraction of the adhesive layer is not particularly limited, but the preferable lower limit is 10% by weight and the preferable upper limit is 70% by weight. If the gel fraction is within the above range, the followability of the adhesive layer to unevenness is improved, and thus the adhesion to a rough surface is further improved, in particular. The more preferable lower limit of the gel fraction is 20% by weight, and the more preferable upper limit is 50% by weight.

[0091] The gel fraction is measured as described below.

[0092] First, a test piece is prepared by cutting the adhesive tape into a flat rectangle of 20 mm x 40 mm, and after the test piece is immersed in ethyl acetate at 23°C for 24 hours, it is taken out of 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 the test piece is not laminated with a release film for protecting the adhesive layer.

[0093] Gel fraction (% by weight) = 100 x (W2 - W0) / (W1 - W0)

[0094] (W0: weight of the substrate, W1: weight of the test piece before immersion, W2: weight of the test piece after immersion and drying)

[0095] The adhesive tape of the present application can exert excellent adhesive force with respect to either of a smooth surface and a rough surface. With respect to the adhesive tape of the present application, the lower limit of the 180° peeling force with respect to glass, as measured in accordance with JIS Z 0237:2009, is preferably 5 N / 25 mm, more preferably 7 N / 25 mm. The upper limit of the 180° peeling force is not particularly limited, and the higher the better, but is substantially about 25 N / 25 mm.

[0096] The 180° peeling force with respect to glass, as measured in accordance with JIS Z 0237:2009, is measured as follows. First, the adhesive tape is cut to a width of 25 mm x a length of 75 mm to produce a test piece. The test piece is placed on a glass plate (surface roughness Ra = 0.2 μm, for example, manufactured by Shenzhen Sun Global Glass Co., Ltd., 2 mm float glass, etc.) in a state in which the adhesive layer thereof faces the glass plate, and a 2 kg rubber roller is reciprocated at a speed of 300 mm / minute once on the test piece, whereby bonding is performed. Thereafter, the test sample is cured at 23°C, 50% humidity for 20 minutes, and the adhesive force (N / 25 mm) is measured in accordance with JIS Z 0237:2009 by peeling the test sample in the 180° direction at a tensile speed of 300 mm / minute under conditions of 23°C, 50% humidity.

[0097] Note that, in the case of a non-supporting tape in which the adhesive tape does not have a substrate or a double-sided adhesive tape in which the adhesive layer is provided on both surfaces of a substrate, a polyethylene terephthalate film (for example, FE2002 manufactured by Futamura Chemical Co., Ltd., or the like) having a thickness of 23 μm is formed as a backing on the surface of the adhesive layer on the other side (the side on which measurement is not performed), and bonding to a glass plate is performed.

[0098] With respect to the adhesive tape of the present application, the lower limit of the 180° peeling force with respect to a polycarbonate plate (PC plate), as measured in accordance with JIS Z 0237:2009, is preferably 5 N / 25 mm, more preferably 7 N / 25 mm. The upper limit of the 180° peeling force is not particularly limited, and the higher the better, but is substantially about 25 N / 25 mm.

[0099] The 180° peeling force with respect to a PC plate, as measured in accordance with JIS Z 0237:2009, is measured in the same manner as the 180° peeling force with respect to glass. As the adherend, a PC plate (surface roughness Ra = 0.2 μm, manufactured by C.I. TAKIRON Co., Ltd., PC-1600, thickness 2 mm, or the like) is used instead of a glass plate.

[0100] The thickness of the adhesive layer in the adhesive tape of the present application is not particularly limited, but the lower limit is preferably 3 μm and the upper limit is preferably 300 μm. If the thickness of the adhesive layer is within the above range, the adhesion of the adhesive composition to smooth and rough surfaces is further improved. The more preferable lower limit of the thickness of the adhesive layer is 5 μm, and the further preferable lower limit is 10 μm. The more preferable upper limit of the thickness of the adhesive layer is 200 μm, and the further preferable upper limit is 100 μm.

[0101] The adhesive tape of the present application can be a non-supporting tape without a substrate, a single-sided adhesive tape having an adhesive layer on one surface of a substrate, or a double-sided adhesive tape having adhesive layers on both surfaces of a substrate.

[0102] The substrate is not particularly limited, and a substrate known in the art can be used, but in order to increase the content of the biologically-derived material in the entire adhesive tape, a biologically-derived substrate is preferably used.

[0103] Examples of the biologically-derived substrate include films and nonwoven fabrics formed of polyesters (PES) such as polyethylene terephthalate (PET), polyethylene furanoate (PEF), polylactic acid (PLA), polytrimethylene terephthalate (PTT), polybutylene terephthalate (PBT), and polybutylene succinate (PBS) derived from plants, and films and nonwoven fabrics formed of polyethylene (PE), polypropylene (PP), polyurethane (PU), triacetyl cellulose (TAC), cellulose, and polyamide (PA) derived from plants.

[0104] From the viewpoint of the strength of the substrate, the substrate is preferably a film formed of PES or a film formed of PA. From the viewpoint of heat resistance and oil resistance, the substrate is preferably a film formed of PA.

[0105] Examples of the film formed of PA include nylon 11, nylon 1010, nylon 610, nylon 510, and nylon 410, which are derived from castor oil, and nylon 56, which is derived from cellulose.

[0106] In addition, from the viewpoint of reducing environmental load by reducing the amount of use of new oil resources and suppressing the amount of emission of carbon dioxide, a substrate using a recycled resource can be used. As a recycling method of resources, for example, the following methods can be given: waste of packaging containers, home electric appliances, automobiles, building materials, foods, and the like, waste generated in a manufacturing process, and the like are collected, and the collected materials are used again as raw materials by washing, removing contamination, or decomposition using heating and fermentation. As a substrate using a recycled resource, for example, a film and a nonwoven fabric formed of PET, PBT, PE, PP, PA, and the like using a material obtained by resinizing recycled plastic again as a raw material can be given. In addition, the collected waste can be combusted and used as heat energy related to the manufacture of the substrate or a raw material thereof, or a material obtained by mixing oil contained in the above waste collected to petroleum, fractionating, and refining can be used as a raw material.

[0107] From the viewpoint of improving compression characteristics, the above substrate can be a foamed substrate.

[0108] As the above foamed substrate, a foamed substrate formed of PE, PP, and / or PU is preferred, and a foamed substrate formed of PE is more preferred from the viewpoint of balancing flexibility and strength at a high level. As a constituent of a foamed substrate formed of PE, for example, PE using sugarcane as a raw material can be given.

[0109] The production method of the above foamed substrate is not particularly limited, and for example, the following method is preferred: a foamable resin composition containing a PE resin containing PE using sugarcane as a raw material and a foaming agent is prepared, the foaming agent is foamed when the foamable resin composition is extrusion-processed into a sheet shape using an extruder, and the obtained polyolefin foam is crosslinked as necessary.

[0110] The thickness of the above foamed substrate is not particularly limited, but the lower limit is preferably 50 μm, and the upper limit is preferably 1000 μm. If the thickness of the above foamed substrate is within the range, high impact resistance can be exerted, and high flexibility that can be closely adhered and attached along the shape of an adherend can be exerted. The more preferred upper limit of the thickness of the above foamed substrate is 300 μm.

[0111] Regarding the adhesive tape of the present application, the lower limit of the total thickness of the adhesive tape (the sum of the thicknesses of the substrate and the adhesive layer) is preferably 3 μm, and the upper limit is preferably 1200 μm. If the total thickness of the adhesive tape is within the above range, the adhesion to smooth surfaces and rough surfaces is further improved. The more preferred upper limit of the total thickness of the above adhesive tape is 500 μm.

[0112] The method for producing the adhesive tape of the present application is not particularly limited, and can be produced by a conventionally known production method. For example, in the case of a double-sided adhesive tape, a method such as the following can be mentioned.

[0113] First, a solution of the adhesive A is prepared by adding a solvent to an acrylic copolymer and, as necessary, a crosslinking agent, a tackifying resin, and the like, and the solution of the 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 overlaid in a state in which the release-treated surface of the release film faces the adhesive layer A.

[0114] Next, a release film different from the above release film is prepared, and a solution of the adhesive B prepared in the same manner as above is applied to the release-treated surface of the release film, and the solvent in the solution is completely dried and removed, whereby a laminated film in which an adhesive layer B is formed on the surface of the release film is prepared. The resulting laminated film is overlaid on the back surface of the substrate in a state in which the adhesive layer B faces the back surface of the substrate on which the adhesive layer A is formed, to prepare a laminate. Then, the above laminate is pressed by a rubber roll or the like, whereby a double-sided adhesive tape having adhesive layers on both surfaces of the substrate and having the surfaces of the adhesive layers covered with the release films can be obtained.

[0115] In addition, two sets of laminated films are prepared in the same manner, and these laminated films are overlaid on both surfaces of a substrate in a state in which the adhesive layers of the laminated films face the substrate, to prepare a laminate, and the laminate is pressed by a rubber roll or the like, whereby a double-sided adhesive tape having adhesive layers on both surfaces of the substrate and having the surfaces of the adhesive layers covered with the release films can also be obtained.

[0116] The use of the adhesive tape of the present application is not particularly limited, but since it has excellent adhesion to either of a smooth surface and a rough surface, and in addition, can have excellent holding power and resistance to springback, and excellent adhesion to a resin adherend formed of polycarbonate or the like, as necessary, it is preferably used for the fixation of electronic device parts or vehicle-mounted parts. Specifically, the adhesive tape of the present application is preferably used for the adhesive fixation of electronic device parts in large-sized portable electronic devices, the adhesive fixation of vehicle-mounted parts (for example, vehicle-mounted panels), and the like.

[0117] In addition, a method for fixing electronic device parts or vehicle-mounted parts using the adhesive tape of the present application is also one of the present application. In addition, a method for producing electronic device parts or vehicle-mounted parts including the method for fixing electronic device parts or vehicle-mounted parts of the present application is also one of the present application. According to these methods, electronic device parts or vehicle-mounted parts can be fixed firmly.

[0118] Effects of the Invention

[0119] According to the present application, it is possible to provide an adhesive composition that exhibits excellent adhesion to either of a smooth surface and a rough surface. In addition, according to the present application, it is possible to provide an adhesive tape having an adhesive layer containing the adhesive composition, and a method for fixing an electronic device component or a vehicle-mounted component using the adhesive tape. BRIEF DESCRIPTION OF DRAWINGS

[0120] Figure 1 A graph for illustrating a shear holding power test of an adhesive tape.

[0121] Figure 2 A graph for illustrating a resilience resistance test of an adhesive tape. DETAILED DESCRIPTION

[0122] Hereinafter, the present application will be described in more detail by citing examples, but the present application is not limited to these examples.

[0123] < Acrylic acid n-heptyl ester >

[0124] Acrylic acid n-heptyl ester was prepared by esterification of n-heptyl alcohol (manufactured by Tokyo Chemical Industry Co., Ltd.) and acrylic acid (manufactured by Japan Catalyst Co., Ltd.).

[0125] < Acrylic acid 1-methylhexyl ester >

[0126] Acrylic acid 1-methylhexyl ester was prepared by esterification of 2-heptyl alcohol (manufactured by Tokyo Chemical Industry Co., Ltd.) and acrylic acid (manufactured by Japan Catalyst Co., Ltd.).

[0127] < Other acrylic monomers >

[0128] The following commercially available monomers were prepared.

[0129] • Butyl acrylate (BA) (manufactured by Mitsubishi Chemical Corporation)

[0130] • 2-Ethylhexyl acrylate (2-EHA) (manufactured by Mitsubishi Chemical Corporation)

[0131] • Acrylic acid (AAc) (manufactured by Japan Catalyst Co., Ltd.)

[0132] • 2-Hydroxyethyl acrylate (2-HEA) (manufactured by Osaka Organic Chemical Industry Co., Ltd.)

[0133] • Tetrahydrofurfuryl acrylate (THFA)

[0134] • Isobornyl acrylate (IBOA)

[0135] < Cross-linking agent >

[0136] An isocyanate-based crosslinking agent (manufactured by DKS Co., Ltd., Coronate L-45) was prepared.

[0137] <Viscosity-increasing resin>

[0138] A commercially available biologically derived viscosity-increasing resin was prepared.

[0139] (1) Terpene phenol resin A (manufactured by Yasuhara Chemical Co., Ltd., G150, softening point: 150°C, biologically derived carbon content: 67% by weight)

[0140] (2) Polymerized rosin ester resin B (hydroxyl value: 46, softening point: 152°C, biologically derived carbon content: 95% by weight)

[0141] (3) Hydrogenated rosin ester resin C (manufactured by Arakawa Chemical Industries, Ltd., KE359, hydroxyl value: 40, softening point: 100°C, biologically derived carbon content: 95% by weight)

[0142] (Example 1)

[0143] (1) Production of acrylic copolymer A (solution polymerization)

[0144] In a reaction vessel, ethyl acetate was added as a polymerization solvent, and after bubbling with nitrogen, the reaction vessel was heated while flowing nitrogen to start reflux. Next, a polymerization initiator solution obtained by diluting 0.1 parts by weight of azobisisobutyronitrile as a polymerization initiator with ethyl acetate 10 times was introduced into the reaction vessel, and 96.6 parts by weight of n-heptyl acrylate, 2.9 parts by weight of acrylic acid, and 0.5 parts by weight of 2-hydroxyethyl acrylate were added dropwise over 2 hours. After the dropwise addition was completed, a polymerization initiator solution obtained by diluting 0.1 parts by weight of azobisisobutyronitrile as a polymerization initiator with ethyl acetate 10 times was again introduced into the reaction vessel, and a polymerization reaction was performed for 4 hours to obtain a solution containing acrylic copolymer A.

[0145] A diluted solution obtained by diluting the obtained acrylic copolymer A with tetrahydrofuran (THF) 50 times was filtered with a filter (material: polytetrafluoroethylene, pore size: 0.2 μm) to prepare a measurement sample. The measurement sample was supplied to a gel permeation chromatograph (manufactured by Waters Co., Ltd., 2690 Separations Model), and GPC measurement was performed under conditions of a sample flow rate of 1 milliliter / minute and a column temperature of 40°C to measure the polystyrene-conversion molecular weight of the acrylic copolymer A, and the weight average molecular weight was calculated.

[0146] (2) Production of adhesive tape

[0147] To the obtained solution containing the acrylic copolymer A, an isocyanate crosslinking agent (Coronate L-45 manufactured by DKS Co., Ltd.) was added so that the solid content thereof was 0.2 parts by weight with respect to 100 parts by weight of the acrylic copolymer A, to prepare an adhesive solution. The adhesive solution was applied to the release-treated surface of a release-treated PET film having a thickness of 75 μm so that the thickness of the dried adhesive layer was 50 μm, and then dried at 110°C for 5 minutes. The adhesive layer was overlaid on the release-treated surface of a release-treated PET film having a thickness of 75 μm, and then cured at 40°C for 48 hours to obtain an adhesive tape (non-support type).

[0148] The release film on one surface of the obtained adhesive tape was peeled off, and a PET film (FE2002 manufactured by Futamura Chemical Co., Ltd.) having a thickness of 23 μm was attached thereto. The adhesive tape was cut into a planar rectangle having a length of 20 mm and a width of 40 mm. Further, the release film on the other surface of the adhesive tape was peeled off, and a test piece was prepared. The weight of the test piece was measured. The test piece was immersed in ethyl acetate at 23°C for 24 hours, and then taken out of the ethyl acetate. The test piece was 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.

[0149] Gel fraction (wt%) = 100 x (W2 - W0) / (W1 - W0)

[0150] (W0: weight of the substrate (PET film), W1: weight of the test piece before immersion, W2: weight of the test piece after immersion and drying)

[0151] The adhesive layer of the obtained adhesive tape was measured using liquid chromatography mass spectrometry (NEXCERA manufactured by Shimadzu Corporation, or Exactive manufactured by Thermo Fisher Scientific Inc.), and the content of the surfactant was calculated.

[0152] (Examples 2 to 11, 13 to 37, Comparative Examples 1 to 6)

[0153] The adhesive tape was obtained by performing the same operations as in Example 1 except that the kind and the blending amount of the acrylic monomer constituting the acrylic copolymer, the weight average molecular weight of the acrylic copolymer, and the kind and the blending amount of the tackifying resin and the crosslinking agent were changed as shown in Tables 1 to 4. In Examples 1 and 27 to 37, the value X of the obtained acrylic copolymer was calculated according to the above formula (1).

[0154] As the tackifying resin, 10 parts by weight of the terpene phenol resin A, 14 parts by weight of the polymerized rosin ester resin B and 10 parts by weight of the hydrogenated rosin ester resin C were used in Examples 10 to 11. In Example 14, 2.9 parts by weight of the terpene phenol resin A, 4.2 parts by weight of the polymerized rosin ester resin B and 2.9 parts by weight of the hydrogenated rosin ester resin C were used. In Example 15, 4.4 parts by weight of the terpene phenol resin A, 6.2 parts by weight of the polymerized rosin ester resin B and 4.4 parts by weight of the hydrogenated rosin ester resin C were used. In Example 16, 14.7 parts by weight of the terpene phenol resin A, 20.6 parts by weight of the polymerized rosin ester resin B and 14.7 parts by weight of the hydrogenated rosin ester resin C were used. In Example 17, 17.6 parts by weight of the terpene phenol resin A, 24.8 parts by weight of the polymerized rosin ester resin B and 17.6 parts by weight of the hydrogenated rosin ester resin C were used.

[0155] (Example 12)

[0156] (1) Production of the acrylic copolymer B (emulsion polymerization)

[0157] To 100 parts by weight of the acrylic monomer mixture described in Table 1 constituting the acrylic copolymer B, which was previously put into another container, 5.8 parts by weight of polyoxyethylene nonylphenyl ether sodium sulfate (manufactured by Kao Corporation, LEVENOL WZ) and 57 parts by weight of deionized water were added, and the mixture was stirred to prepare an emulsion of the monomer mixture.

[0158] To the reaction vessel were added 40 parts by weight of deionized water and 0.2 parts by weight of polyoxyethylene nonylphenyl ether sodium sulfate, and nitrogen was flowed in, and the temperature was raised to 80°C. Thereafter, 4 parts by weight of an aqueous solution of potassium persulfate dissolved at a concentration of 5% was added to the reaction vessel. The previously prepared emulsion of the monomer mixture was added dropwise to the reaction vessel over a period of 3 hours, and in parallel therewith, 4 parts by weight of an aqueous solution of potassium persulfate dissolved at a concentration of 5% was added dropwise, and emulsion polymerization was performed at an internal temperature of 80 to 83°C. After the completion of the dropwise addition, the temperature was maintained at the same temperature for 3 hours, and then the reaction solution was cooled to room temperature, and 25% ammonia water was added to adjust the pH to 7.5, and an emulsified copolymer having an average particle diameter of 210 nm was obtained.

[0159] To the obtained solution containing the emulsified copolymer were added a basic tackifying acrylic tackifier (manufactured by Saiden Chemical Industry Co., Ltd., Saivinol AZ-1), 25% ammonia water and deionized water, and a solution containing the acrylic copolymer B having a solid content concentration of 50%, a viscosity of 3500 mPa-s and a pH of 8.0 was obtained.

[0160] The weight average molecular weight of the obtained acrylic copolymer B was not determinable.

[0161] (2) Production of the adhesive tape

[0162] The same operation as in Example 1 was performed except that the obtained acrylic copolymer B was used, to obtain an adhesive tape. The gel fraction and the content of the surfactant were found in the same manner as in Example 1.

[0163] < EVALUATION >

[0164] The adhesive tapes obtained in the Examples and Comparative Examples were evaluated by the following methods. The results are shown in Tables 1 to 4.

[0165] (1) Peeling force against a smooth surface

[0166] The 180° peeling force of the adhesive tape against glass as a smooth surface was measured in accordance with JIS Z 0237:2009.

[0167] Specifically, first, one face of the adhesive tape (the side on which measurement was not performed) was lined with a polyethylene terephthalate film (Futamura Chemical Co., Ltd., FE2002) having a thickness of 23 μm, and the adhesive tape was cut into a width of 25 mm and a length of 75 mm to produce a test piece. The test piece was placed on a glass plate (surface roughness Ra = 0.2 μm, Shenzhen SunGlobal Glass Co., Ltd., 2 mm float glass, etc.) so as to be in a state in which the adhesive layer (the side on which measurement was performed) of the test piece faced the glass plate, and a 2 kg rubber roller was reciprocated once at a speed of 300 mm / minute on the test piece, whereby the test piece was attached to the glass plate. Thereafter, the test sample was allowed to stand for 20 minutes at 23°C and 50% humidity, and was peeled in the 180° direction at a tensile speed of 300 mm / minute in accordance with JIS Z 0237:2009, to measure the adhesive force (N / 25 mm).

[0168] (2) Peeling force against a rough surface

[0169] The 180° peeling force of the adhesive tape against water-resistant abrasive paper (NORITAKE COATED ABRASIVE Co., Ltd., C947H, grit 360, surface roughness Ra = 10.8 μm) as a rough surface was measured in accordance with JIS Z 0237:2009.

[0170] Specifically, first, the back surface of the water-resistant abrasive paper was attached to a SUS304 plate using an adhesive tape for measurement (manufactured by Shachihata Co., Ltd., #560). Next, after lining one face of the adhesive tape (the side on which measurement was not performed) with a polyethylene terephthalate film (manufactured by Futamura Chemical Co., Ltd., FE2002) having a thickness of 23 μm, a test piece was prepared by cutting to a width of 25 mm and a length of 75 mm. After the test piece was placed on the polishing surface of the water-resistant abrasive paper attached to the SUS304 plate so as to face the adhesive layer (the side on which measurement was performed) of the adhesive tape to the polishing surface, the test piece was attached by reciprocating a rubber roller of 2 kg at a speed of 300 mm / min once. Thereafter, the test sample was prepared by leaving it under conditions of 23°C and 50% humidity for 20 minutes. The adhesive force (N / 25 mm) was measured by peeling the test sample in the 180° direction at a tensile speed of 300 mm / min in accordance with JIS Z 0237.

[0171] Note that the surface roughness Ra of the water-resistant abrasive paper was measured using a laser microscope (manufactured by KEYENCE Co., Ltd., color 3D laser microscope, VK-8710).

[0172] (3) Peeling force with respect to a polycarbonate plate (PC plate)

[0173] The 180° peeling force of the adhesive tape with respect to a polycarbonate plate (PC plate) was measured in accordance with JIS Z 0237:2009 for the adhesive tapes obtained in Examples 1 and 18 to 26.

[0174] Specifically, first, after lining one face of the adhesive tape (the side on which measurement was not performed) with a polyethylene terephthalate film (manufactured by Futamura Chemical Co., Ltd., FE2002) having a thickness of 23 μm, a test piece was prepared by cutting to a width of 25 mm and a length of 75 mm. After the test piece was placed on a PC plate (surface roughness Ra = 0.2 μm, manufactured by C.I. TAKIRON Co., Ltd., PC-1600, thickness 2 mm) so as to face the adhesive layer (the side on which measurement was performed) of the adhesive tape to the PC plate, the test piece was attached by reciprocating a rubber roller of 2 kg at a speed of 300 mm / min once. Thereafter, the test sample was prepared by leaving it under conditions of 23°C and 50% humidity for 20 minutes. The adhesive force (N / 25 mm) was measured by peeling the test sample in the 180° direction at a tensile speed of 300 mm / min in accordance with JIS Z 0237:2009 under conditions of 23°C and 50% humidity.

[0175] (4) Shear holding power test

[0176] Shear holding power test was performed on the adhesive tape obtained in Examples 1 and 27 to 37.

[0177] Figure 1 A graph for schematically showing the shear holding power test of the adhesive tape.

[0178] As shown in Figure 1 , a 23 μm-thick polyethylene terephthalate film (Futamura Chemical Co., FE2002) 5 and a SUS plate 7 were adhered using the adhesive tape 6. The adhering area was set to 25 mm x 25 mm. A 1 kg weight 8 was hung from one end of the polyethylene terephthalate film 5, and the shift amount (distance of shift of the adhesive tape) (mm) of the adhesive tape after 1 hour was measured while standing at a temperature of 80°C.

[0179] (5) Resilience resistance test

[0180] Resilience resistance test was performed on the adhesive tape obtained in Examples 1 and 27 to 37.

[0181] Figure 2 A graph for schematically showing the resilience resistance test of the adhesive tape.

[0182] As shown in Figure 2 , the adhesive tape 9 was cut into a planar rectangle of 25 mm in the lateral direction x 150 mm in the longitudinal direction, and an aluminum plate 10 of 25 mm in the lateral direction x 150 mm in the longitudinal direction x 0.3 mm in thickness and a polycarbonate resin plate 11 of 25 mm in the lateral direction x 200 mm in the longitudinal direction x 1 mm in thickness were adhered using the adhesive tape 9. The adjustment was performed in such a manner that the adhesive tape 9 was positioned at the central portion of the polycarbonate resin plate 11 in the longitudinal direction. The polycarbonate resin plate 11 was integrated with the aluminum plate 10 by the adhesive tape 9 by reciprocating a 2 kg rubber roll at a speed of 300 mm / minute once on the polycarbonate resin plate 11, and a test sample 12 was prepared by standing at 23°C for 24 hours. Figure 2 As shown in , the test sample 12 was set to a jig 13, and the test sample 12 was deformed to a state of being curved in a circular arc shape in such a manner that the distance between both ends in the longitudinal direction of the polycarbonate resin plate 11 was 180 mm by applying a bending stress in the longitudinal direction of the test sample 12. The test sample 12 was left in an oven at 85°C in this state for 24 hours. The test sample 12 was taken out of the oven while being kept in the state of being curved in a circular arc shape, and the floating height H (mm) between the aluminum plate 10 and the polycarbonate resin plate 11 was measured with a vernier caliper.

[0183]

[0184]

[0185]

[0186]

[0187] Industrial applicability

[0188] According to the present application, it is possible to provide an adhesive composition that exhibits excellent adhesion with respect to either of a smooth surface and a rough surface. In addition, according to the present application, it is possible to provide an adhesive tape having an adhesive layer containing the adhesive composition, and a fixing method and a manufacturing method of an electronic device member or a vehicle-mounted member using the adhesive tape.

[0189] Symbol mark description

[0190] 5 Polyethylene terephthalate film

[0191] 6 Adhesive tape

[0192] 7 SUS plate

[0193] 8 Weight (1 kg)

[0194] 9 Adhesive tape

[0195] 10 Aluminum plate

[0196] 11 Polycarbonate resin plate

[0197] 12 Test sample

[0198] 13 Jig

Claims

1. An adhesive tape, characterized by an adhesive layer containing an adhesive composition containing an acrylic copolymer having a structural unit derived from n-heptyl (meth)acrylate, a crosslinking agent, and a tackifying resin, a gel fraction of the adhesive layer is 70% by mass or less, the content of the structural unit derived from n-heptyl (meth)acrylate in the acrylic copolymer is 25% by mass or more, the acrylic copolymer further has a structural unit derived from a monomer having a crosslinkable functional group, the content of the structural unit derived from the monomer having a crosslinkable functional group in the acrylic copolymer is 0.01% by mass or more and 20% by mass or less, the content of the tackifying resin is 60 parts by mass or less with respect to 100 parts by mass of the acrylic copolymer, the content of the crosslinking agent is 0.05 parts by mass or more and 7 parts by mass or less with respect to 100 parts by mass of the acrylic copolymer.

2. The adhesive tape according to claim 1, characterized by the content of the structural unit derived from n-heptyl (meth)acrylate in the acrylic copolymer is 48% by mass or more.

3. The adhesive tape according to claim 1, wherein the content of the structural unit derived from n-heptyl (meth)acrylate in the acrylic copolymer is 60% by mass or more.

4. The adhesive tape according to claim 1, 2 or 3, characterized in that, the content of the structural unit derived from a (meth)acrylate having an alkyl group having a carbon number of 8 or more in the acrylic copolymer is 50% by mass or less.

5. The adhesive tape according to claim 1, 2 or 3, characterized in that, the content of the structural unit derived from the monomer having a crosslinkable functional group in the acrylic copolymer is 0.5% by mass or more and 5% by mass or less.

6. The adhesive tape according to claim 1, 2 or 3, characterized in that, the monomer having a crosslinkable functional group is a monomer having a hydroxyl group, and a value X of the acrylic copolymer represented by the following formula (1) is 2 or more and 50 or less, In formula (1), Mw polymer represents the weight average molecular weight of the acrylic copolymer, W OH represents the content of the structural unit derived from the monomer having a hydroxyl group in the acrylic copolymer, W total represents the content of the total monomers constituting the acrylic copolymer, M OH represents the molecular weight of the monomer having a hydroxyl group, and n represents the hydroxyl value of the monomer having a hydroxyl group, and the W OH and the W total are expressed in parts by weight.

7. The adhesive tape according to claim 6, wherein the value X is 5 or more and 30 or less.

8. The adhesive tape according to claim 1, 2 or 3, characterized in that, the acrylic copolymer has a structural unit derived from at least one monomer selected from tetrahydrofurfuryl (meth)acrylate and isobornyl (meth)acrylate, and the content of the structural unit derived from at least one monomer selected from tetrahydrofurfuryl (meth)acrylate and isobornyl (meth)acrylate is 1% by mass or more and 40% by mass or less.

9. The adhesive tape according to claim 1, 2 or 3, characterized in that, the weight average molecular weight of the acrylic copolymer is 200,000 or more and 2,000,000 or less.

10. The adhesive tape according to claim 1, 2 or 3, characterized in that, the tackifying resin is at least one selected from a rosin ester-based tackifying resin and a terpene-based tackifying resin.

11. The adhesive tape according to claim 1, 2 or 3, characterized in that, does not contain a surfactant.

12. The adhesive tape according to claim 1, 2 or 3, characterized in that, the content of carbon derived from a living organism is 10% by mass or more.

13. The adhesive tape according to claim 1, 2 or 3, characterized in that, the gel fraction of the adhesive layer is 10% by mass or more.

14. The adhesive tape according to claim 1, 2 or 3, characterized in that, the 180° peeling force with respect to glass measured in accordance with JIS Z 0237:2009 is 7 N / 25 mm or more.

15. The adhesive tape according to claim 1, 2 or 3, characterized in that, the 180° peeling force with respect to a polycarbonate plate measured in accordance with JIS Z 0237:2009 is 7 N / 25 mm or more.

16. The adhesive tape according to claim 1, 2 or 3, characterized in that, it is used for fixing an electronic device component or a vehicle-mounted component.

17. A method of fixing an electronic equipment component or a vehicle-mounted component, characterized by an electronic device component or a vehicle-mounted component is fixed using the adhesive tape according to claim 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, or 16.

18. A method for manufacturing an electronic device component or a vehicle component, characterized by, a method for fixing an electronic device component or a vehicle-mounted component including the electronic device component or the vehicle-mounted component according to claim 17.

Images