Adhesive compositions, copolymer dispersions, kits, tapes, and adhesive methods

Abstract

An adhesive composition comprising a copolymer (A), a crosslinking agent (B), and an aqueous medium, wherein the copolymer (A) has structural units derived from a monomer (a1), structural units derived from a monomer (a2) having a carboxyl group, and structural units derived from a monomer (a3) ​​having an alkoxysilyl group, wherein the monomer (a1) is composed of either or both of an alkyl (meth)acrylate having only one olefinic double bond and a hydrocarbon having only one olefinic double bond, wherein the structural units in the copolymer (A) derived from the monomer (a2) are relative to those derived from the monomer (a1). The content of the structural unit in the copolymer (A) is 1.0 part by mass or more and 12 parts by mass or less in 100 parts by mass, and the content of the structural unit derived from the monomer (a3) ​​in the copolymer (A) is 0.010 parts by mass or more and 3.5 parts by mass or less in 100 parts by mass relative to the structural unit derived from the monomer (a1). The crosslinking agent (B) contains one or more selected from polycarbodiimide compounds, polyepoxide compounds and polyisocyanate compounds, and the content of the crosslinking agent (B) is 0.010 parts by mass or more and 10 parts by mass or less in 100 parts by mass relative to the copolymer (A).

Description

Technical Field

[0001] This invention relates to adhesive compositions, copolymer dispersions, sleeves, tapes, and bonding methods. Background Technology

[0002] Adhesive tape is a representative application of adhesives. Adhesive tape forms an adhesive layer on a substrate, and is used to repair various items or to hold items together. Additionally, double-sided tape, with adhesive layers formed on both sides of the substrate, is widely used in transportation equipment such as automobiles, household appliances, and stationery.

[0003] Representative methods for manufacturing adhesive tapes include: applying a coating solution containing an adhesive dissolved or dispersed in a liquid medium onto a substrate and allowing it to dry, thus forming an adhesive layer on the substrate surface. Adhesives widely use natural rubber, synthetic rubber, and acrylic rubber, with acrylic adhesives being particularly noteworthy for their ability to impart various functionalities. In recent years, water has been increasingly studied as a liquid medium.

[0004] For example, Patent Document 1 describes a wafer processing tape, characterized in that an acrylic resin emulsion adhesive compound solution, formed by adding a volatile surfactant to an acrylic resin emulsion adhesive polymerized using a reactive surfactant, is coated onto a substrate film. It describes obtaining an acrylic resin emulsion adhesive by polymerizing a monomer containing a carboxylic acid vinyl compound. Furthermore, there are examples of adding tetramethylolpropionate tris-β-aziridinium propionate to the adhesive compound solution.

[0005] Patent Document 2 describes a re-peelable adhesive sheet in which the adhesive layer contains adhesive microparticles, an adhesive, a tackifier, and a crosslinking agent having carbodiimide groups. Furthermore, in the examples, acrylic acid is used as a monomer in the synthesis of the adhesive microparticles.

[0006] Patent document 3 describes, in Example 1, an aqueous dispersion of an acrylic adhesive comprising a copolymer formed by copolymerizing a monomer containing acrylic acid and an epoxy crosslinking agent. Furthermore, in Example 3, etc., a copolymer formed by copolymerizing acrylic acid and a silane coupling agent and... Aqueous dispersions of acrylic adhesives with zozoline-based crosslinking agents.

[0007] Patent Document 4 discloses a peelable aqueous adhesive composition comprising an emulsion obtained by emulsion polymerization of a monomer mixture containing (meth)acrylate, a carboxyl-containing unsaturated monomer, a multifunctional unsaturated monomer, and other unsaturated monomers, and a crosslinking agent. Furthermore, monomers having alkoxysilyl groups can be exemplified as other unsaturated monomers. In addition, the crosslinking agent is described as being selected from... At least one of the following: azoline compounds, carbodiimide compounds, epoxy compounds, and aziridine compounds.

[0008] Existing technical documents

[0009] Patent documents

[0010] Patent Document 1: Japanese Patent Application Publication No. 5-171117

[0011] Patent Document 2: Japanese Patent Application Publication No. 2005-126479

[0012] Patent Document 3: Japanese Patent Application Publication No. 2013-189645

[0013] Patent Document 4: Japanese Patent Application Publication No. 2004-256789 Summary of the Invention

[0014] Inventions aim to solve problems.

[0015] In the solutions of patent documents 1 and 2, there is room for improvement in adhesion and holding power under high temperature conditions.

[0016] The solution of Example 1 in Patent Document 3, when applied to adhesive tape, has room for improvement in holding power under high temperature conditions. Furthermore, the solutions of Example 2, etc., in Patent Document 3, when applied to adhesive tape, have room for improvement in adhesion and holding power under high temperature conditions.

[0017] The solution in Patent Document 4 also has room for improvement in adhesion and holding power under high-temperature conditions. Furthermore, the range of alkoxysilane concentrations required to achieve a full effect is narrow, and no specific concentration is specified to obtain the desired effect. Moreover, in this document, the monomer containing alkoxysilane is merely one of many exemplified monomers, and its effect is not discussed at all.

[0018] Therefore, the objective of this invention is to provide an adhesive composition that exhibits strong adhesive force not only at room temperature but also at high temperatures, thereby forming an adhesive layer with high holding power even at high temperatures. Furthermore, the objective of this invention is to provide a tape that exhibits strong adhesive force not only at room temperature but also at high temperatures, and also has high holding power even at high temperatures.

[0019] Problem-solving methods

[0020] [1]. An adhesive composition comprising a copolymer (A), a crosslinking agent (B), and an aqueous medium,

[0021] The copolymer (A) has structural units derived from monomers (a1), structural units derived from monomers having carboxyl groups (a2), and structural units derived from monomers having alkoxysilyl groups (a3).

[0022] The monomer (a1) is composed of either or both of an alkyl (meth)acrylate having only one olefinic double bond and a hydrocarbon having only one olefinic double bond.

[0023] In the copolymer (A), the content of structural units derived from the monomer (a2) relative to 100 parts by mass of structural units derived from the monomer (a1) is 1.0 part by mass or more and 12 parts by mass or less.

[0024] In the copolymer (A), the content of structural units derived from the monomer (a3) ​​relative to 100 parts by mass of structural units derived from the monomer (a1) is 0.010 parts by mass or more and 3.5 parts by mass or less.

[0025] The crosslinking agent (B) contains one or more compounds selected from polycarbodiimide compounds, polyepoxide compounds, and polyisocyanate compounds.

[0026] The content of the crosslinking agent (B) is 0.010 parts by mass or more and 10 parts by mass or less relative to 100 parts by mass of the copolymer (A).

[0027] [2]. According to the adhesive composition of [1], the copolymer (A) has structural units derived from a monomer (a4) having hydroxyl groups, wherein the content of structural units derived from the monomer (a4) in the copolymer (A) is 0.10 parts by mass or more and 10 parts by mass or less of 100 parts by mass relative to structural units derived from the monomer (a1).

[0028] [3]. According to the adhesive composition of [1] or [2], the copolymer (A) does not have structural units from compounds having multiple independent olefinic unsaturated double bonds.

[0029] [4]. The adhesive composition according to any one of [1] to [3], wherein the copolymer (A) contains a total of more than 90% by mass of structural units from the monomer (a1), structural units from the monomer (a2), and structural units from the monomer (a3).

[0030] [5]. The adhesive composition according to any one of [1] to [4], wherein the glass transition temperature of the copolymer (A) is above -80°C and below 30°C.

[0031] [6]. The adhesive composition according to any one of [1] to [5], wherein the monomer (a1) is composed of alkyl (meth)acrylate.

[0032] [7]. The adhesive composition according to any one of [1] to [6], wherein the total content of dialkoxysilyl and trialkoxysilyl in all alkoxysilyl groups contained in the copolymer (A) is 80 mol% or more.

[0033] [8]. The adhesive composition according to any one of [1] to [7], wherein the copolymer (A) contains at least 70 mol% of the trialkoxysilyl groups of all alkoxysilyl groups.

[0034] [9]. In any one of [1] to [8], the crosslinking agent (B) is a polycarbodiimide compound.

[0035]

[10] . According to the adhesive composition of [9], the carbodiimide equivalent of the crosslinking agent (B) is 150 or more and 1000 or less.

[0036]

[11] . In any one of [1] to [8], the crosslinking agent (B) is a polyepoxide compound.

[0037]

[12] . According to the adhesive composition of

[11] , the crosslinking agent (B) has an epoxy equivalent of 70 or more and 700 or less.

[0038]

[13] . The adhesive composition according to any one of [1] to

[12] contains a total content of the copolymer (A) and the crosslinking agent (B) in the non-volatile components of 50% by mass or more.

[0039]

[14] . A copolymer dispersion for preparing the adhesive composition described in any one of [1] to

[13] , comprising copolymer (A) and an aqueous medium,

[0040] The copolymer (A) has structural units derived from monomer (a1), structural units derived from monomer (a2) having a carboxyl group, and structural units derived from monomer (a3) ​​having an alkoxysilyl group.

[0041] The monomer (a1) is composed of either or both of an alkyl (meth)acrylate having only one olefinic double bond and a hydrocarbon having only one olefinic double bond.

[0042] In the copolymer (A), the content of structural units derived from the monomer (a2) relative to 100 parts by mass of structural units derived from the monomer (a1) is 1.0 part by mass or more and 12 parts by mass or less.

[0043] The content of structural units derived from the monomer (a3) ​​in the copolymer (A) is 0.010 parts by mass or more and 3.5 parts by mass or less per 100 parts by mass relative to structural units derived from the monomer (a1).

[0044]

[15] . A sleeve for preparing adhesive compositions, comprising a copolymer dispersion and a crosslinking agent (B),

[0045] The copolymer dispersion contains copolymer (A) and an aqueous medium.

[0046] The copolymer (A) has structural units derived from monomer (a1), structural units derived from monomer (a2) having a carboxyl group, and structural units derived from monomer (a3) ​​having an alkoxysilyl group.

[0047] The monomer (a1) is composed of either or both of an alkyl (meth)acrylate having only one olefinic double bond and a hydrocarbon having only one olefinic double bond.

[0048] In the copolymer (A), the content of structural units derived from the monomer (a2) relative to 100 parts by mass of structural units derived from the monomer (a1) is 1.0 part by mass or more and 12 parts by mass or less.

[0049] In the copolymer (A), the content of structural units derived from the monomer (a3) ​​relative to 100 parts by mass of structural units derived from the monomer (a1) is 0.010 parts by mass or more and 3.5 parts by mass or less.

[0050] The crosslinking agent (B) contains one or more compounds selected from polycarbodiimide compounds, polyepoxide compounds, and polyisocyanate compounds.

[0051] The crosslinking agent (B) content is 0.010 parts by mass or more and 10 parts by mass or less relative to 100 parts by mass of the copolymer (A).

[0052]

[16] . A tape having a substrate and an adhesive layer formed on the surface of the substrate,

[0053] The adhesive layer contains a cured product of the adhesive composition described in any one of [1] to

[13] .

[0054]

[17] . An adhesive method using the tape described in

[16] .

[0055]

[18] . A method for manufacturing an adhesive tape, comprising:

[0056] The process of applying the adhesive composition described in any one of [1] to

[13] onto a substrate, and

[0057] The process of removing the aqueous medium from the adhesive composition applied to the substrate to form an adhesive layer.

[0058] Invention Effects

[0059] According to the present invention, an adhesive composition can be provided that exhibits strong adhesive force not only at room temperature but also at high temperatures, and can form an adhesive layer with high holding power at high temperatures. In this specification, adhesive force is defined as "the force generated by the contact between the adhesive surface of the adhesive sheet or tape and the adhered object," referring to the force required to peel off the adhesive. In this specification, holding power is defined as "the force borne by the adhesive when a static load is applied along the length of the adhesive sheet or tape to the adhered object and it shifts," representing the strength of the cohesive force of the adhesive layer. Furthermore, according to the present invention, a tape that exhibits strong adhesive force not only at room temperature but also at high temperatures, and also has high holding power at high temperatures, can be provided. Detailed Implementation

[0060] Unless otherwise specified, "surface" is used in the following description.

[0061] "(Meth)acrylic acid" is a general term for acrylic acid and methacrylic acid, and "(meth)acrylate" is a general term for acrylate and methacrylate.

[0062] "Alkenyl unsaturated double bond" refers to an alkene unsaturated double bond that is capable of free radical polymerization, unless otherwise stated.

[0063] In a polymer of a compound having an olefinic double bond, a structural unit derived from that compound is considered to have the same chemical structure as the portion of that structural unit in the polymer other than the olefinic double bond. For example, a structural unit derived from acrylic acid has a structure represented by -CH2CH(COOH)- in the polymer.

[0064] In the following description, the compound that is the source of a structural unit refers to a compound that has the above-described relationship with that structural unit, and does not need to be the same as the monomer used in the actual manufacturing process.

[0065] Furthermore, for structural units with ionic functional groups such as carboxyl groups, unless otherwise specified, they are considered structural units from the same ionic compound, regardless of whether a portion of the functional group has undergone ion exchange. For example, a structural unit represented by -CH2C(CH3)(COONa)- is also considered to be a structural unit from methacrylic acid.

[0066] Furthermore, for compounds with multiple independent olefinic unsaturated double bonds, these bonds can also remain as structural units in polymers. Multiple independent olefinic unsaturated double bonds refer to multiple olefinic unsaturated double bonds that do not form conjugated dienes with each other. For example, a divinylbenzene structural unit can be a structure without any olefinic unsaturated double bonds (where the portion corresponding to any olefinic unsaturated double bond is incorporated into the polymer chain), or it can be a structure with only one olefinic unsaturated double bond (where only the portion corresponding to that single olefinic unsaturated double bond is incorporated into the polymer chain).

[0067] Furthermore, in cases where, after polymerization, functional groups other than those corresponding to the unsaturated double bonds of the olefin, such as carboxyl, hydroxyl, alkoxysilyl, and epoxy groups, undergo chemical reactions to introduce ester structures or other functional groups, the chemical structure after the reaction is used as the reference when the chemical structure of the monomer does not correspond to that of the polymer. For example, in the case of polymerizing vinyl acetate and then saponifying it, the structural units after saponification are considered based on the chemical structure of the polymer and are not structural units derived from vinyl acetate, but rather from vinyl alcohol. However, the chemical structure obtained by chemically reacting the alkoxysilyl group of the structural unit obtained from the monomer (a3) ​​containing alkoxysilyl groups after polymerization is considered to be a structural unit derived from the monomer (a3) ​​containing alkoxysilyl groups.

[0068] "Non-volatile component" refers to the component remaining after weighing 1g of the composition into a 5cm diameter aluminum pan and drying it at 105°C for 1 hour under air circulation in a desiccator at 1 atmosphere (1013hPa). The composition may be in the form of a solution, dispersion, or slurry, but is not limited to these. "Non-volatile component concentration" refers to the mass ratio (mass %) of the non-volatile component after drying relative to the mass (1g) of the composition before drying under the stated conditions.

[0069] In this specification, "adhesive" means the cured product of the adhesive composition, that is, the article obtained by removing moisture from the adhesive composition and curing it.

[0070] In one embodiment, the adhesive is obtained by drying the adhesive composition at 100°C for 3 minutes and then allowing it to stand at 40°C for 3 days to cure. It is assumed that the crosslinking reaction of the adhesive composition is completed during the 3-day standing period at 40°C.

[0071] In addition, in this specification, "adhesive composition coating layer" refers to a layer formed on the substrate or the like after removing the aqueous medium from the adhesive composition coated on the substrate or release paper (hereinafter referred to as the substrate, etc.).

[0072] By curing the adhesive composition coating layer, an adhesive layer can be obtained.

[0073] In one embodiment, the adhesive layer is obtained by curing the adhesive composition coating layer by allowing it to stand at 40°C for 3 days.

[0074] The adhesive layer can also be formed by transferring an adhesive composition coating layer formed on release paper to a substrate such as nonwoven fabric, and then curing it by standing at 40°C for 3 days.

[0075] <1. Adhesive Composition>

[0076] The adhesive composition of this embodiment comprises a copolymer (A), a crosslinking agent (B), and an aqueous medium. Other additives may also be included in the adhesive composition.

[0077] [1-1. Copolymer (A)]

[0078] The copolymer (A) is a polymer of a compound having an olefinic unsaturated double bond. The copolymer (A) comprises structural units derived from a monomer (a1) described later, structural units derived from a monomer having a carboxyl group (a2), and structural units derived from a monomer having an alkoxysilyl group (a3). Furthermore, the copolymer (A) preferably contains at least one of the structural units derived from a monomer having a hydroxyl group (a4) and other compounds (a6) such as chain transfer agents, and more preferably contains both. Additionally, the copolymer (A) may contain structural units derived from other monomers (a5) that are not among monomers (a1) to (a4).

[0079] Furthermore, copolymer (A) preferably does not have structural units derived from compounds having multiple independent olefinic unsaturated double bonds. Examples of compounds having multiple independent olefinic unsaturated double bonds include divinylbenzene and ethylene glycol dimethacrylate.

[0080] [1-1-1. Monomer (a1)]

[0081] The monomer (a1) is composed of either or both of an alkyl (meth)acrylate and a hydrocarbon having an olefinic unsaturated double bond. The monomer (a1) has only one olefinic unsaturated double bond. The monomer (a1) preferably contains an alkyl (meth)acrylate, more preferably is composed of an alkyl (meth)acrylate. The monomer (a1) may contain one compound or two or more compounds.

[0082] Among the monomers (a1), examples of alkyl methacrylates include methyl methacrylate, ethyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, tert-butyl methacrylate, cyclohexyl methacrylate, 2-ethylhexyl methacrylate, lauryl methacrylate, stearyl methacrylate, and isobornyl methacrylate. Methyl methacrylate, n-butyl methacrylate, and 2-ethylhexyl methacrylate are preferred because their physical properties are easily controlled.

[0083] Examples of hydrocarbons containing olefinic unsaturated double bonds include styrene, α-methylstyrene, p-methylstyrene, ethylene, and propylene. Considering the manufacturing cost of copolymer (A), styrene, which readily generates free radicals, is preferred as a hydrocarbon containing olefinic unsaturated double bonds.

[0084] In copolymer (A), the glass transition temperature of copolymer (A) can be adjusted according to the types and proportions of structural units contained in monomer (a1). Structural units that lower the glass transition temperature of copolymer (A) include, but are not limited to, structural units from 2-ethylhexyl acrylate and structural units from butyl acrylate. Structural units that raise the glass transition temperature of copolymer (A) include, but are not limited to, structural units from methyl methacrylate and structural units from styrene.

[0085] [1-1-2. Monomer (a2)]

[0086] Monomer (a2) has a carboxyl group. In this invention, a monomer having an alkoxysilyl group (i.e., a monomer that meets the definition of monomer (a3)) and also having a carboxyl group is considered equivalent to monomer (a3), but not equivalent to monomer (a2). The carboxyl group may partially or completely form a salt, but the salt formation ratio is preferably 10% or less based on the number (mol number). Preferably, monomer (a2) does not have multiple independent olefinic unsaturated double bonds. Monomer (a2) is preferably a compound having olefinic unsaturated double bonds and a carboxyl group.

[0087] Examples of compounds containing olefinic unsaturated double bonds and carboxyl groups include, for example, acrylic acid, methacrylic acid, crotonic acid, citracic acid, itaconic acid, maleic acid, maleic anhydride, fumaric acid, 2-carboxyethyl acrylate oligomer, 2-acryloyloxyethyl succinic acid, and other α,β-unsaturated monocarboxylic or dicarboxylic acids; and carboxyl-containing vinyl compounds such as phthalic acid mono[(meth)acrylate monohydroxyethyl ester] ester and oxalate mono[(meth)acrylate monohydroxypropyl ester] ester; etc., and more than one of them may be used.

[0088] As a monomer (a2), it may contain one compound or two or more compounds. The monomer (a2) is preferably (meth)acrylic acid, and more preferably composed of (meth)acrylic acid.

[0089] The mechanism by which the heat resistance is improved by using a monomer (a2) with a carboxyl group is not yet known, but the inventors speculate that it is based on the following mechanism: It is speculated that the carboxyl group of the structural unit derived from the monomer (a2) reacts with the functional group of the crosslinking agent (B) described later to form intermolecular crosslinks (external crosslinks), and these crosslinks impart cohesion to the adhesive layer, thereby improving the heat resistance of the adhesive layer.

[0090] [1-1-3. Monomer (a3)]

[0091] The monomer (a3) ​​has an alkoxysilyl group. The monomer (a3) ​​preferably does not have multiple independent olefinic unsaturated double bonds, and more preferably has only one olefinic unsaturated double bond.

[0092] The total content of dialkoxysilyl and trialkoxysilyl groups in all alkoxysilyl groups contained in copolymer (A) is preferably 80 mol% or more, more preferably 90 mol% or more, and even more preferably 100 mol%. The content of trialkoxysilyl groups in all alkoxysilyl groups contained in copolymer (A) is preferably 70 mol% or more, more preferably 80 mol% or more, even more preferably 90 mol% or more, and particularly preferably 100 mol%. This is because the crosslinking density inside copolymer (A) is increased, and the heat resistance of the adhesive layer is improved.

[0093] Here, the oxygen atom bonded to the silicon atom and the alkyl group bonded through the oxygen atom in the alkoxysilane are collectively referred to as "alkoxy groups contained in the alkoxysilane". For example, the trialkoxysilane contains three alkoxy groups. The total content of ethoxy and methoxy groups in all the alkoxysilanes contained in the copolymer (A) is preferably 70 mol% or more, more preferably 80 mol% or more, further preferably 90 mol% or more, and particularly preferably 100 mol%. This is because the reactivity of the alkoxysilane is increased, making it easier to adjust the crosslinking density within the copolymer (A) by adjusting the amount of alkoxysilane.

[0094] The monomer (a3) ​​is preferably a compound having an olefinic unsaturated double bond and an alkoxysilyl group. As a monomer (a3) ​​having an alkoxysilyl group, compounds represented by the following general formula (1) are preferably listed.

[0095]

[0096] In general formula (1), R 1Indicates methacryloyloxy, acryloyloxy, or vinyl, R 2 ~R 4 R represents an alkoxy group having 1 to 20 carbon atoms or an alkyl group having 1 to 20 carbon atoms, respectively. 2 ~R 4 At least one of them is an alkoxy group having 1 to 20 carbon atoms. n represents an integer from 0 to 20.

[0097] n is preferably 1 to 10, more preferably 1 to 5. The alkoxy group having 1 to 20 carbon atoms preferably has 1 to 8 carbon atoms, more preferably 1 to 3 carbon atoms, and particularly preferably 1 or 2 carbon atoms. The alkyl group having 1 to 20 carbon atoms preferably has 1 to 8 carbon atoms, more preferably 1 to 3 carbon atoms, and particularly preferably 1 or 2 carbon atoms.

[0098] Examples of alkoxy groups with 1 to 20 carbon atoms include methoxy, ethoxy, propoxy, butoxy, pentoxy, and octoxy. Examples of alkyl groups with 1 to 20 carbon atoms include methyl, ethyl, n-propyl, isopropyl, butyl, pentyl, hexyl, octyl, 2-ethylhexyl, decyl, dodecyl, tetradecyl, hexadecyl, and octadecyl.

[0099] As monomers represented by general formula (1), vinyltriethoxysilane, vinyltri(β-methoxyethoxy)silane, 3-methacryloyloxypropyltrimethoxysilane, and other α,β-vinyl unsaturated compounds with hydrolyzable alkoxysilanes are preferred. As monomer (a3), 3-methacryloyloxypropyltrimethoxysilane (R in general formula (1)) is more preferred. 1 It is methacryloyloxy, R 2 ~R 4 All compounds are methoxyl groups, n=3. For example, 3-methacryloyloxypropyltrimethoxysilane can be represented by "KBM-503" manufactured by Shin-Etsu Chemical Co., Ltd. The monomer (a3) ​​may contain only one compound or two or more compounds.

[0100] [1-1-4. Monomer (a4)]

[0101] Monomer (a4) has a hydroxyl group. In this invention, a monomer having an alkoxysilyl group (i.e., a monomer that meets the definition of monomer (a3)) and having a hydroxyl group is considered equivalent to monomer (a3) ​​but not equivalent to monomer (a4).

[0102] Because copolymer (A) has structural units derived from monomer (a4), the adhesion strength of the adhesive layer is further enhanced at high temperatures. Although the mechanism has not yet been determined, the inventors speculate that it is caused by the following mechanism: that is, it is speculated that the hydroxyl groups of the structural units derived from monomer (a4) react with the alkoxysilyl groups of the structural units derived from monomer (a3) ​​to form intramolecular crosslinks (internal crosslinks), and / or the hydroxyl groups of the structural units derived from monomer (a4) react with the functional groups of the crosslinking agent (B) described later to form intermolecular crosslinks (external crosslinks), which further enhance the adhesion strength of the adhesive layer at high temperatures.

[0103] The compound derived from monomer (a4) preferably does not have multiple independent olefinic unsaturated double bonds, and more preferably has only one olefinic unsaturated double bond. Monomer (a4) is preferably a compound having an olefinic unsaturated double bond and a hydroxyl group.

[0104] The monomer (a4) is preferably a (meth)acrylate having a hydroxyl group, more preferably a (meth)acrylate alkyl having a hydroxyl group, i.e., a (meth)acrylate hydroxyalkyl. Examples of monomers (a4) include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, and other (meth)acrylate hydroxyalkyl. Among these, 2-hydroxyethyl (meth)acrylate is more preferred, and 2-hydroxyethyl methacrylate is even more preferred. The monomer (a4) may contain only one compound or may contain two or more compounds.

[0105] [1-1-5. Monomer (a5)]

[0106] Monomer (a5) is a compound with an olefinic unsaturated double bond and does not belong to any of monomers (a1) to (a4).

[0107] As monomers (a5), examples include alkylamino (meth)acrylates such as N,N-dimethylaminoethyl (meth)acrylate and N,N-dimethylaminopropyl (meth)acrylate; vinyl ester compounds such as vinyl formate, vinyl acetate, vinyl propionate, and vinyl esters of Versatic acid (branched fatty acids with 9 to 11 carbon atoms); conjugated diene compounds such as butadiene, isoprene, and chloroprene; vinyl compounds containing aminoimide groups such as 1,1,1-trimethylamine methacrylamide; and cyanide vinyl compounds such as acrylonitrile and methacrylonitrile. (Methacrylamide) compounds such as (meth)acrylamide, N-methyl(meth)acrylamide, N,N-dimethyl(meth)acrylamide, and N,N-dimethylaminopropyl(meth)acrylamide; α,β-olefinic unsaturated compounds containing sulfonyl groups such as allyl sulfonate and sodium p-styrenesulfonate; UV absorbers with free radical polymerization properties such as 2-(2'-hydroxy-5'-methacryloyloxyethylphenyl)-2H-benzotriazole; and light stabilizers with free radical polymerization properties such as 1,2,2,6,6-pentamethyl-4-piperidinyl methacrylate.

[0108] [1-1-6. Other Compounds (a6)]

[0109] In this specification, "other compound (a6)" refers to a compound that forms a structure or structural unit in the copolymer (A) other than the structural units derived from the monomers (a1) to (a5). Examples of this compound (a6) include polymerization initiators, chain transfer agents, etc., used in the synthesis of the copolymer (A). Furthermore, unlike the monomers (a1) to (a5), the structure of the polymerization initiator, chain transfer agent, etc., may not have the aforementioned correspondence with the other compound (a6) in the copolymer (A).

[0110] In this embodiment, the content of structural units from compounds such as monomers and chain transfer agents can be calculated by using the amount of each compound added to manufacture copolymer (A).

[0111] [1-1-7. Content of each structural unit]

[0112] The copolymer (A) preferably contains 90% by mass or more of structural units from monomer (a1), structural units from monomer (a2), and structural units from monomer (a3), more preferably 95% by mass or more, and even more preferably 97% by mass or more. This is to suppress the rise in the glass transition temperature of the copolymer (A) and improve the tack, wettability, and thus the adhesion of the adhesive layer.

[0113] The structural unit from monomer (a2) accounts for 1.0 part by mass or more, preferably 2.0 part by mass or more, and more preferably 3.0 part by mass or more, of 100 parts by mass relative to the structural unit from monomer (a1). This is to improve the cohesiveness of the adhesive layer and enhance its heat resistance.

[0114] The content of structural units from monomer (a2) relative to 100 parts by mass of structural units from monomer (a1) is 12 parts by mass or less, preferably 8.0 parts by mass or less, and more preferably 6.0 parts by mass or less. This is because the polarity of the copolymer (A) and the cohesiveness of the adhesive layer are appropriately maintained, resulting in an adhesive layer with high adhesion.

[0115] The content of structural units from monomer (a3) ​​relative to 100 parts by mass of structural units from monomer (a1) is 0.010 parts by mass or more, more preferably 0.020 parts by mass or more, and even more preferably 0.030 parts by mass or more. This is to improve the cohesiveness of the adhesive layer and improve its heat resistance.

[0116] The content of structural units from monomer (a3) ​​relative to 100 parts by mass of structural units from monomer (a1) is 3.5 parts by mass or less, preferably 2.0 parts by mass or less, more preferably 1.2 parts by mass or less, even more preferably 0.60 parts by mass or less, even more preferably 0.12 parts by mass or less, and particularly preferably 0.060 parts by mass or less. This is to properly maintain the cohesiveness of the adhesive layer and obtain an adhesive layer with high adhesion.

[0117] The content of structural units from monomer (a4) relative to 100 parts by mass of structural units from monomer (a1) is preferably 0.10 parts by mass or more, more preferably 0.20 parts by mass or more, and even more preferably 0.30 parts by mass or more. This is to improve the retention strength of the adhesive layer under high temperature conditions.

[0118] The content of structural units from monomer (a4) relative to 100 parts by mass of structural units from monomer (a1) is preferably 10 parts by mass or less, more preferably 5.0 parts by mass or less, even more preferably 1.5 parts by mass or less, and particularly preferably 0.60 parts by mass or less. This is to properly maintain the polarity of the copolymer (A) and the cohesiveness of the adhesive layer, thereby obtaining an adhesive layer with sufficient adhesion.

[0119] [1-1-8. Glass transition temperature of copolymer (A)]

[0120] The glass transition temperature (Tg) of copolymer (A) is preferably -80°C or higher, more preferably -65°C or higher, and even more preferably -55°C or higher. This is to improve the cohesiveness of the adhesive and impart better heat resistance to the adhesive layer.

[0121] The glass transition temperature of copolymer (A) is preferably below 30°C, more preferably below 0°C, further preferably below -20°C, and particularly preferably below -35°C. This is to improve the wettability of the adhesive composition described later and to improve the adhesion of the adhesive layer to the substrate. In addition, this is to improve the flexibility of the adhesive layer and to improve the tackiness of the adhesive layer when used dry.

[0122] Tg is a theoretical value calculated using FOX's formula shown below, based on the monomer units that make up the polymer and their proportions.

[0123] 1 / T=W1 / T1+W2 / T 2+W3 / T 3+…+Wn / Tn

[0124] T(K) = Tg(°C) + 273°C, where T is the absolute temperature value of the glass transition temperature of copolymer (A). Additionally, Wn is the mass fraction of each structural unit (≤1), and Tn is the absolute temperature of the homopolymer of the compound from which each structural unit originates. Furthermore, in this specification, the glass transition temperatures of each homopolymer are those described in known sources. Specifically, the values ​​listed in the literature "Polymer Handbook (3rd edition, John Wiley & Sons, Inc., 1989)" are used.

[0125] [1-1-9. Preparation method of copolymer (A)]

[0126] The method for manufacturing copolymer (A) is not particularly limited. Compounds that will be the source of the structural units constituting copolymer (A) can be polymerized as monomers, or some or all of the structural units can be polymerized with other compounds and then converted into target structural units by introducing functional groups, etc. Examples of methods for manufacturing copolymer (A) include emulsifying monomers in an aqueous medium and performing emulsion polymerization using a polymerization initiator. During polymerization, chain transfer agents can be used to control the molecular weight and distribution of the copolymer within an appropriate range. Emulsifiers can also be used to emulsify the monomers. The monomers can be added to the reactor in full beforehand, and to obtain uniform particles, a mixture containing all types of monomers used to form the structural units of copolymer (A) can be fed continuously or intermittently, and polymerization can be carried out simultaneously with the addition. The polymerization temperature is not particularly limited, but is preferably 5–100°C, more preferably 50–90°C.

[0127] Aqueous media are water, hydrophilic solvents, or mixtures thereof. Examples of hydrophilic solvents include methanol, ethanol, isopropanol, and N-methylpyrrolidone. From the viewpoint of polymerization stability, water is preferred as the aqueous medium. However, water with added hydrophilic solvents can also be used as the aqueous medium, provided that polymerization stability is not compromised.

[0128] Examples of polymerization initiators used in emulsion polymerization include persulfate initiators such as potassium persulfate and ammonium persulfate, water-soluble azo initiators such as 2,2'-azobis(2-methylpropanediamine) dihydrochloride, organic peroxides such as tert-butyl hydroperoxide and cumene hydroperoxide, and hydrogen peroxide. These polymerization initiators can be used alone or in combination. The amount of polymerization initiator used relative to the total amount of monomer is preferably 0.1% to 2% by mass.

[0129] Additionally, reducing agents can be used in conjunction with these polymerization initiators as needed. Examples of such reducing agents include reducing organic compounds such as ascorbic acid, tartaric acid, citric acid, glucose, and formaldehyde sulfite metal salts, as well as reducing inorganic compounds such as sodium thiosulfate, sodium sulfite, sodium bisulfite, and sodium metabisulfite.

[0130] Examples of chain transfer agents include, but are not limited to, n-dodecyl mercaptan, tert-dodecyl mercaptan, n-butyl mercaptan, 2-ethylhexyl mercaptoacetate, 2-mercaptoethanol, β-mercaptopropionic acid, methanol, n-propanol, isopropanol, tert-butanol, and benzyl alcohol. Only one chain transfer agent may be used, or two or more may be used.

[0131] Decreasing the amount of chain transfer agent increases the cohesive strength and heat resistance of the adhesive; increasing it decreases the cohesive strength but increases the adhesive strength of the adhesive layer. The amount of chain transfer agent used is preferably 0.0010 parts by mass or more, more preferably 0.050 parts by mass or more, and even more preferably 0.080 parts by mass or more, relative to 100 parts by mass of the total amount of monomers that are the source of each structural unit in the copolymer (A). This is to form an adhesive layer with strong adhesion.

[0132] The amount of chain transfer agent used is preferably 5.0 parts by mass or less, more preferably 2.0 parts by mass or less, even more preferably 0.50 parts by mass or less, and particularly preferably 0.20 parts by mass or less, relative to the total amount of monomers that become the source of each structural unit in copolymer (A). This is to improve the heat resistance of the adhesive layer.

[0133] As an emulsifier, there are no particular limitations. Specifically, examples include anionic surfactants such as sodium dodecylbenzenesulfonate and sodium dodecyl sulfate, nonionic surfactants such as polyoxyethylene alkyl ethers and polyoxyethylene nonylphenyl ether, cetyltrimethylammonium bromide, and laurylpyridine chloride. Cationic surfactants, amphoteric surfactants such as lauryl betaine, and other reactive surfactants are also available. These surfactants can be used alone or in combination of two or more.

[0134] [1-2. Crosslinking agent (B)]

[0135] The crosslinking agent (B) may comprise one or more compounds selected from polycarbodiimide compounds (compounds having multiple carbodiimide groups (structures represented by -N=C=N-), polyepoxide compounds (compounds having multiple epoxy groups), and polyisocyanate compounds (compounds having multiple isocyanate groups). Additionally, the epoxy group may be part of a glycidyl group. The crosslinking agent (B) may be a carbodiimide compound having epoxy groups. Polycarbodiimide compounds and polyepoxide compounds are particularly preferred because they can impart high adhesive strength and cohesiveness to the adhesive. The crosslinking agent (B) is preferably a water-soluble or water-dispersible compound.

[0136] Examples of polycarbodiimide compounds include, for instance, p-phenylene-bis(2,6-dimethylcarbodiimide), tetramethylene-bis(tert-butylcarbodiimide), and cyclohexane-1,4-bis(methylene-tert-butylcarbodiimide), or Nissin Textile Kemica Co., Ltd.'s "Carbodilight (registered trademark, hereinafter the same) V-02", "Carbodilight SV-02", "Carbodilight V-04", "Carbodilight V-10", "Carbodilight E-02", "Carbodilight E-03A", and "Carbodilight E-05".

[0137] The carbodiimide equivalent (molecular weight corresponding to each carbodiimide group) of the polycarbodiimide compound is preferably 150 or more, more preferably 250 or more, further preferably 300 or more, and particularly preferably 350 or more. This is to suppress steric hindrance in the crosslinking reaction with the copolymer (A) and to increase the rate and density of the crosslinking reaction.

[0138] The carbodiimide equivalent (molecular weight corresponding to each carbodiimide group) of the polycarbodiimide compound is preferably 1000 or less, more preferably 750 or less, and even more preferably 600 or less. This is to increase the crosslinking density in the crosslinking reaction with the copolymer (A).

[0139] Examples of polyepoxy compounds include bisphenol A epichlorohydrin type epoxy resins and sorbitol polyglycidyl ethers (e.g., "Denacol EX-611", "Denacol EX-612", "Denacol EX-614", and "Denacol EX-612" manufactured by Nagasekex Co., Ltd.). 4B", "Doctor EX-622", etc.), polyglycerol polyglycidyl ether (for example, "Doctor EX-512" manufactured by Dorothy Co., Ltd., "Petrol EX-521", etc.), pentaerythritol polyglycidyl ether (for example, "Petrol EX-411" manufactured by Pedrotech Co., Ltd., etc.), diglycerol polyglycidyl ether Glycidyl ether (e.g., "Denacol EX-421" manufactured by Nagasecex Co., Ltd.), glycerol polyglycidyl ether (e.g., "Denacol EX-313" and "Denacol EX-314" manufactured by Nagasecex Co., Ltd.), trimethylolpropane polyglycidyl ether (e.g., "Denacol EX-421" manufactured by Nagasecex Co., Ltd.) Denacol EX-321, etc.), resorcinol diglycidyl ether (e.g., Denacol EX-201 manufactured by Nagasekemtex Co., Ltd.), neopentyl glycol diglycidyl ether (e.g., Denacol EX-211 manufactured by Nagasekemtex Co., Ltd.), 1,6-hexanediol diglycidyl ether (e.g., Nagasekemtex...). "Temporex EX-212" manufactured by Ketotech Co., Ltd., etc.), hydrogenated bisphenol A diglycidyl ether Glycolic acid, for example, "Tactyl EX-252" manufactured by Nasuku Co., Ltd., etc.), ethylene glycol diglycidyl ether (e.g., Nostalgic Co., Ltd.) "Dosneli EX-810", "Dosneli EX-811", etc. manufactured by the company), diethylene glycol diglycidyl ether (e.g., "Session" manufactured by the Nose Co., Ltd. Polyethylene glycol diglycidyl ether (e.g., Polyethylene glycol diglycidyl ether (for example, Polyethylene glycol EX-850", "Dorum EX-851", etc.) produced by Nailtech Co., Ltd. "デナコールEX-830", "デナコールEX-832", "デナコールEX-841", "デナコールEX-8" 61", etc.), propylene glycol diglycidyl ether (e.g., "Nanosac EX-911" manufactured by Nasuku Co., Ltd., etc.), polypropylene glycol diglycidyl ether (e.g., Examples of active ingredients include "Denacor EX-941", "Denacor EX-920", and "Denacor EX-931" manufactured by Nagasekex Co., Ltd., as well as diglycidyl aniline, diglycidylamine, N,N,N',N'-tetraglycidyl-m-phenylenediamine, and 1,3-bis(N,N'-diglycidylaminomethyl)cyclohexane. Water-soluble types are preferred.

[0140] The epoxy equivalent (molecular weight per epoxy group) of the polyepoxide compound is preferably 70 or more, more preferably 100 or more. This is to suppress steric hindrance in the crosslinking reaction with the copolymer (A) and to increase the rate and density of the crosslinking reaction.

[0141] The epoxy equivalent (molecular weight per epoxy group) of the polyepoxide compound is preferably 700 or less, more preferably 400 or less, even more preferably 300 or less, and particularly preferably 200 or less. This is to increase the crosslinking density in the crosslinking reaction with the copolymer (A).

[0142] Examples of polyisocyanate compounds include toluene diisocyanate, 4,4'-diphenylmethane diisocyanate, hexamethylene diisocyanate, xylene diisocyanate, m-xylene diisocyanate, 1,5-naphthalene diisocyanate, hydrogenated diphenylmethane diisocyanate, hydrogenated toluene diisocyanate, hydrogenated xylene diisocyanate, isophorone diisocyanate, and tetramethylphenyl dimethylene diisocyanate. Examples of specific products include biuret polyisocyanate compounds such as "Sumicon N" (manufactured by Sumitomo Biotech Co., Ltd.); "Desuzu IL" and "Desu Polyisocyanate compounds having an isocyanurate ring, such as "Micro HL" (manufactured by Boko AG) and "Korea EH" (manufactured by Nippon Japan Co., Ltd.); "Micro" Addition polyisocyanate compounds such as "L" (manufactured by Sumitomo Biorevitan Co., Ltd.) and "Coronato HL" (manufactured by Nippon Polyrevitan Co., Ltd.); and self-emulsifying water-dispersible polyisocyanate compounds such as "Aquanet 100", "Aquanet 110", "Aquanet 200", and "Aquanet 210" (manufactured by Nippon Polyrevitan Co., Ltd.). Among these, water-dispersible polyisocyanate compounds are preferred. Alternatively, blocked isocyanate compounds can also be used as polyisocyanate compounds.

[0143] The isocyanate equivalent (molecular weight corresponding to each isocyanate group) of the polyisocyanate compound is preferably 60 or more, more preferably 75 or more. This is to suppress steric hindrance in the crosslinking reaction with the copolymer (A) and to increase the rate and density of the crosslinking reaction.

[0144] The isocyanate equivalent (molecular weight corresponding to each isocyanate group) of the polyisocyanate compound is preferably 500 or less, more preferably 200 or less, and even more preferably 100 or less. This is to increase the crosslinking density in the crosslinking reaction with the copolymer (A).

[0145] [1-3. The quantitative relationship between copolymer (A) and crosslinking agent (B)]

[0146] In the adhesive composition, the crosslinking agent (B) accounts for 0.010 parts by mass or more, preferably 0.020 parts by mass or more, more preferably 0.050 parts by mass or more, further preferably 0.15 parts by mass or more, and particularly preferably 0.40 parts by mass or more, relative to 100 parts by mass of the copolymer (A). This is because the increased crosslinking density between particles improves the cohesiveness of the adhesive and the strength of the adhesive layer.

[0147] In the adhesive composition, the crosslinking agent (B) is present in an amount of 10 parts by weight or less, preferably 5.0 parts by weight or less, more preferably 3.0 parts by weight or less, and even more preferably 1.0 parts by weight or less, relative to 100 parts by weight of copolymer (A). This is because the flexibility of the adhesive layer is improved, resulting in stronger adhesion.

[0148] [1-4. Aqueous Media]

[0149] The aqueous medium is water, a hydrophilic solvent, or a mixture thereof. Examples of hydrophilic solvents include methanol, ethanol, isopropanol, and N-methylpyrrolidone. Water is preferred as the aqueous medium. The aqueous medium may have the same composition as the aqueous solvent used for the polymerization of copolymer (A), or it may have a different composition.

[0150] [1-5. Other additives]

[0151] Additives may be appropriately included in the adhesive composition as needed. There are no particular limitations on the timing of adding additives. Additives may be added simultaneously with or after mixing the copolymer (A) and crosslinking agent (B). Alternatively, additives may be added to either or both solutions or dispersions before mixing the copolymer (A) and crosslinking agent (B). Examples of additives include pH adjusters and tackifiers. Additionally, plasticizers, antioxidants, fillers, pigments, colorants, wetting agents, defoamers, and tackifiers may be appropriately used as additives.

[0152] As pH adjusters, common acidic substances such as inorganic acids and organic acids, as well as their salts and amphoteric salts such as amino acids, can be used. Examples of organic acid pH adjusters include acetic acid, formic acid, glycolic acid, malic acid, citric acid, maleic acid, fumaric acid, malonic acid, phthalic acid, isophthalic acid, lactic acid, butyric acid, ascorbic acid, succinic acid, tartaric acid, acrylic acid, methacrylic acid, crotonic acid, adipic acid, oxalic acid, and rosin acid. Examples of inorganic acid pH adjusters include boric acid, phosphoric acid, hydrochloric acid, nitric acid, nitrous acid, sulfuric acid, and sulfurous acid. Furthermore, examples of salts of acidic substances include salts of the aforementioned organic or inorganic acids with sodium, potassium, ammonia, aminoethanol, diethanolamine, and triethanolamine. Additionally, examples of amino acid pH adjusters include glycine, diglycine peptide, asparagine, aspartic acid, alanine, phenylalanine, arginine, glutamine, and glutamic acid. These pH adjusters can be used alone or in combination of two or more.

[0153] Examples of tackifiers include rosin resin, rosin ester resin, hydrogenated rosin resin, polymerized rosin resin, α-pinene resin, β-pinene resin, terpene phenol resin, C5 fraction petroleum resin, C9 fraction petroleum resin, C5 / C9 fraction petroleum resin, dicyclopentadiene petroleum resin, alkylphenol resin, xylene resin, coumarone resin, and coumarone-indene resin. Tackifiers can be used alone or in combination of two or more.

[0154] [1-6. Content of each component in the adhesive composition]

[0155] The concentration of non-volatile components in the adhesive composition is preferably 20% by mass or more, more preferably 30% by mass or more, and even more preferably 40% by mass or more. This is because more adhesive layers can be formed with a smaller coating amount of the adhesive composition. Furthermore, this is because the drying time of the coated adhesive composition is shortened, increasing productivity.

[0156] The concentration of non-volatile components in the adhesive composition is preferably 75% by mass or less, more preferably 65% ​​by mass or less. This is to suppress gelation of copolymer (A) in the adhesive composition.

[0157] In the adhesive composition, the total content of the copolymer (A) and crosslinking agent (B) in the non-volatile components is preferably 50% by mass or more, more preferably 60% by mass or more, and even more preferably 70% by mass or more. This is to improve the adhesive strength and holding power of the adhesive layer, especially the holding power at high temperatures.

[0158] In the adhesive composition, the total content of the copolymer (A) and crosslinking agent (B) in the non-volatile components is preferably 90% by mass or less, more preferably 80% by mass or less.

[0159] [1-7. Sleeves for preparing adhesive compositions]

[0160] The adhesive composition of this embodiment can also be stored as a kit containing multiple dosage forms of its constituent components, which are divided into multiple additives.

[0161] Alternatively, a copolymer dispersion containing the copolymer (A) and an aqueous medium and a crosslinking agent (B) can be prepared in advance as a kit, and the copolymer dispersion and crosslinking agent (B) can be mixed to prepare the adhesive composition when using the adhesive composition.

[0162] <2. Adhesive Tape>

[0163] [2-1. Tape Structure]

[0164] As a representative application of the adhesive composition of the present invention, there is an adhesive tape. The tape of this embodiment comprises a substrate and an adhesive layer formed on the surface of the substrate. The adhesive layer may be formed on only one side of the substrate or on both sides. Furthermore, in the tape of the present invention, the adhesive layer may also be protected by a known release liner such as release paper or release PET.

[0165] The material used as the substrate is not particularly limited and can include paper, plastic, cloth, metal, etc. Furthermore, the substrate can be a film, woven fabric, or non-woven fabric; there are no particular limitations, but non-woven fabric is preferred. This is because the adhesive composition, when immersed in the substrate, increases the bonding strength between the adhesive layer and the substrate. Additionally, in this invention, "substrate" refers to the portion of the adhesive tape used on the adhered object, that is, the portion adhered to the adhered object along with the adhesive layer during application, excluding release liner such as release paper that is peeled off when using the tape.

[0166] The adhesive layer contains an adhesive as a cured product of the adhesive composition. In addition to the adhesive, the adhesive layer may also contain additives or the like found in the adhesive composition. As described below, in tapes made by applying an adhesive composition to a substrate, the adhesive layer contains a non-volatile component of the adhesive composition. The thickness of the adhesive layer is preferably 10 μm or more, more preferably 30 μm or more, and even more preferably 50 μm or more. This is because the adhesive layer can be sufficiently deformed to follow the surface of the adhered object. The thickness of the adhesive layer is preferably 200 μm or less, more preferably 100 μm or less. This is to suppress coagulation and breakage of the adhesive layer. The adhesive layer may comprise two or more adhesive layers.

[0167] In addition to the substrate and adhesive layer, the tape of the present invention may also have other layers (such as intermediate layer, primer layer, etc.) without impairing the effect of the invention.

[0168] [2-2. Manufacturing method of adhesive tape]

[0169] The method for manufacturing adhesive tape includes: a step of coating an adhesive composition onto one or both sides of a substrate; and a step of removing an aqueous medium from the adhesive composition coated on the substrate to form an adhesive layer. During coating, an aqueous medium or tackifier may be appropriately added to the adhesive composition to adjust its viscosity. When coating the adhesive composition on both sides, it can be applied one side at a time or applied to both sides simultaneously. The adhesive composition can be applied continuously to the substrate or intermittently.

[0170] The coating amount of the adhesive composition is not particularly limited, but is preferably 10–500 g / m². 2 The drying temperature of the adhesive composition applied to the substrate is not particularly limited, but is preferably 20–160°C. This is because an adhesive layer with sufficient adhesion and cohesion can be obtained.

[0171] <3. Applications of Adhesive Compositions and Tapes>

[0172] Here, adhesive tape has been described as one of the preferred uses of the adhesive composition of the present invention, but the uses of the adhesive composition of the present invention are not limited thereto. For example, the adhesive composition of the present invention can also be applied directly to the component and bonded to other components without using adhesive tape. In addition, as for the use of adhesive tape and bonding methods characterized by the use of adhesive tape, there are applications such as in electrical products, automobiles, building components, toys, etc. The materials to be bonded by the adhesive tape are not particularly limited, but it is particularly useful for materials to be bonded to plastic parts such as polypropylene, metal parts such as SUS, and aluminum.

[0173] Example

[0174] Hereinafter, embodiments and comparative examples of the present invention will be described. However, the present invention is not limited to the embodiments.

[0175] <1. Preparation of Adhesive Composition>

[0176] In a polymerization apparatus equipped with a stirrer, thermometer, and reflux condenser, 23 parts by mass of ion-exchanged water and 0.10 parts by mass of Akalon KH-10 (manufactured by Daiichi Kogyo Pharmaceutical Co., Ltd.) as emulsifier were mixed, and the mixture was heated to 80°C under a nitrogen atmosphere. While stirring the mixture in the polymerization apparatus and maintaining it at 80°C, 2 parts by mass of a 5.0% by mass potassium persulfate aqueous solution were added as a polymerization initiator. A monomer emulsion containing 50 parts by mass of ion-exchanged water, 1.0 part by mass of emulsifier, and a total of 100 parts by mass of monomer and chain transfer agent was added dropwise to the mixture containing the polymerization initiator over 4 hours.

[0177] The types of monomers and chain transfer agents added here are shown in Tables 1, 2-1, and 2-2 of the respective examples and comparative examples. The content of each component in a total of 100 parts by mass of monomers and chain transfer agents added here is shown in the left column of each example and comparative example in Tables 1, 2-1, and 2-2. The usage amount of monomers and chain transfer agents relative to 100 parts by mass of monomer (a1) is shown in the right column of each example and comparative example in Tables 1, 2-1, and 2-2. Simultaneously with the start of adding the monomer emulsion, 20 parts by mass of a 2.5% potassium persulfate aqueous solution were added dropwise over 4 hours.

[0178] After the addition was completed, the reaction was carried out at 80°C for 2 hours. Then, the mixture in the polymerization apparatus was cooled to 25°C. Ammonia was added as a neutralizing agent to adjust the pH to 8.5. Then, 25 parts by weight of Super Ester E-865NT (manufactured by Arakawa Chemical Industry Co., Ltd.) as a tackifier and 2.0 parts by weight of Primal ASE-60 (manufactured by Dookemical Co., Ltd.) as a tackifier were added. Then, crosslinking agents (crosslinking agent (B) or other crosslinking agents) of the types and amounts shown in the left column of Tables 1, 2-1 and 2-2 were added in each example and comparative example to obtain adhesive compositions. In addition, the amount of crosslinking agent added in the following tables refers to "the amount of crosslinking agent added (parts by weight) relative to 100 parts by weight of copolymer (A)".

[0179]

[0180]

[0181]

[0182] <2. Making the tape>

[0183] The adhesive compositions obtained in the various examples and comparative examples were applied to the release surface of release paper (KP-8D manufactured by Hayashi Compare Tech Co., Ltd.). A squeegee with a coating width of 15 cm was used as the applicator. The applied adhesive composition was dried at 100°C for 3 minutes to remove the aqueous medium from the adhesive composition, forming an adhesive composition coating layer with a thickness of 60 μm on the release surface. The adhesive composition coating layer on the release surface was then transferred to an A4-sized sheet with a thickness of 40 μm and a weight per unit area of ​​14 g / m². 2 The adhesive composition transferred onto both sides of a nonwoven fabric (substrate: made of rayon) is coated and cured at 40°C for 3 days to form an adhesive layer. This yields a tape with a substrate and an adhesive layer formed on the substrate surface. Furthermore, to prevent foreign matter from adhering to the adhesive layer, the release paper is not peeled off even after the transfer.

[0184] <3. Evaluation of the tape>

[0185] The tapes produced in each embodiment and comparative example were evaluated as follows. The evaluation results are shown in Tables 1, 2-1, and 2-2. Furthermore, in the following description, the operations in each embodiment and comparative example are common unless otherwise specified.

[0186] [3-1. Evaluation 1: Measurement]

[0187] Peel off the release paper from one side of the adhesive tape and attach a 25μm thick polyethylene terephthalate (PET) film. Cut a 25mm × 250mm piece from this film. Then, peel off half of the release paper from the opposite side of the adhesive tape along its length and cut it off, then attach it to a polypropylene (PP) board to prepare an evaluation sample. The bonding is performed by running a 2kg roller back and forth once at 23°C. In the evaluation sample, the portion of the tape bonded to the PP board forms a 25mm × 125mm rectangle. The ends of the bonded portion do not overlap with the ends of the PP board. That is, in this state, one half of the tape along its length is bonded to the PP board, and the other half is bonded to the release paper.

[0188] After preparing the evaluation samples, they were placed in an atmosphere at 23°C for 30 minutes. Then, the following measurements were performed in an atmosphere at 23°C.

[0189] The test is a so-called 180° peel test. The tape used for evaluation is folded back 180° along the boundary between the portion adhered to and the unadheded portion of the polypropylene sheet. The end of the tape not adhered to the polypropylene sheet (the folded-back side) is gripped by the upper chuck of the testing machine (Tensilon RTG-1210, manufactured by A. Ande Co., Ltd.). The end of the polypropylene sheet, which is clamped along the fold line and opposed to the upper chuck, is gripped by the lower chuck.

[0190] In this state, the adhesive tape was peeled from the polypropylene board at a speed of 200 mm / min, resulting in a graph of peel length (mm) versus peel force (N). From the obtained graph, the average peel force (N) for peel lengths of 25–100 mm was calculated (the area of ​​the graph for peel lengths of 25–100 mm divided by the peel length value), and this value was taken as the initial adhesive force (N / 25 mm). Furthermore, in both embodiments and comparative examples, no peeling between the adhesive layer and the substrate, or cohesion failure of the adhesive layer, occurred during the test.

[0191] [3-2. Evaluation 2: Determination of adhesive strength under high temperature conditions]

[0192] After preparing the evaluation samples following the same steps as described above, they were placed in a constant temperature bath at 70°C for 30 minutes. Then, a 180° peel test was performed under an atmosphere at 70°C, following the steps described above. The average peel force (mN) when the peel length was 25–100 mm was taken as the adhesion force after high-temperature storage (N / 25 mm). Furthermore, an AutoGrav AG-X (manufactured by Shimadzu Corporation) was used as the testing machine for the high-temperature environment measurement.

[0193] [3-3. Evaluation 3: Determination of High-Temperature Holding Power]

[0194] Peel off the release paper from one side of the adhesive double-sided tape and apply a 25 μm thick polyethylene terephthalate (PET) film. Peel off 25 mm of the release paper from one end along the length of the other side of the tape, and then apply the SUS board (SUS#304) to cover the entire area where the release paper has been peeled off, thus creating an evaluation specimen. Specifically, in the evaluation specimen, the area where the tape and SUS board are bonded is a 25 mm × 25 mm square. Bonding is performed by passing a 2 kg roller back and forth once at 23°C. Furthermore, only the portion of the SUS board not bonded to the tape at the extended end of the tape bonded to the SUS board is designated as the SUS board side chuck portion.

[0195] The evaluation sample was placed in a constant temperature bath at 80°C for 30 minutes. Then, inside the constant temperature bath at 80°C, a holding force testing machine (manufactured by Tester Sangyo Co., Ltd.) was used. The SUS plate side chuck of the evaluation sample was gripped by a chuck, and a 500g counterweight was suspended at the end of the tape not attached to the SUS plate along its length. The test was conducted for 24 hours. Then, the vertical deviation (mm) of the tape relative to the SUS plate was measured.

[0196] <4. Evaluation Results>

[0197] As shown in Table 1, the tape made using the adhesive composition of the examples exhibits strong adhesion not only at room temperature but also at high temperatures, thereby forming an adhesive layer with high retention at high temperatures.

[0198] On the other hand, in the copolymer (A), in the tapes of Comparative Examples 1-4 and Comparative Examples 8-11 made using an adhesive composition that does not contain structural units from monomers (a3) ​​having alkoxysilyl groups, at least one of high-temperature adhesion and high-temperature holding power is insufficient.

[0199] Among these, in Comparative Example 2, the amount of crosslinking agent (B) in the adhesive composition was increased, but the initial adhesive force and high-temperature adhesive force of the tape decreased. Furthermore, in Comparative Examples 3 and 4, a polyepoxide compound was used as the crosslinking agent (B), but the high-temperature holding power or high-temperature adhesive force of the tape was insufficient. Therefore, it can be seen that in a structure where the copolymer (A) does not contain structural units derived from monomers (a3) ​​having alkoxysilyl groups, the objective of the present invention cannot be achieved, regardless of increasing the amount of crosslinking agent (B) in the adhesive composition or changing the type of functional groups of the crosslinking agent (B).

[0200] Furthermore, in the comparative examples, the tapes of Comparative Example 9, which used more ethylene glycol dimethacrylate instead of monomer (a3), and Comparative Example 11, which used more divinylbenzene, exhibited insufficient initial adhesion. Additionally, the tapes of Comparative Example 8, which used a small amount of ethylene glycol dimethacrylate instead of monomer (a3), and Comparative Example 10, which used a small amount of divinylbenzene, showed significantly poor high-temperature retention. Therefore, it can be seen that even if structural units from compounds having multiple independent olefinic unsaturated double bonds are introduced instead of structural units from monomers (a3) ​​having alkoxysilyl groups in the copolymer (A), the objectives of the present invention cannot be achieved.

[0201] In copolymer (A), the tape of Comparative Example 5, made using an adhesive composition containing an excess of structural units from monomer (a3), had insufficient initial adhesion and high-temperature adhesion.

[0202] In Comparative Example 6, the tape made using an adhesive composition containing an excess of crosslinking agent (B) exhibited insufficient initial adhesion and high-temperature adhesion. On the other hand, in Comparative Example 7, the tape made using an adhesive composition with a low content of crosslinking agent (B) showed significantly poor initial adhesion and high-temperature adhesion.

[0203] Using In Comparative Example 12, where the zolyl crosslinking agent was used instead of crosslinking agent (B), the high-temperature adhesion and high-temperature retention were insufficient.

[0204] As described above, according to the present invention, a water-dispersible adhesive composition can be provided that exhibits strong adhesive force not only at room temperature but also at high temperatures, and can form an adhesive layer with high holding power at high temperatures. Furthermore, according to the present invention, a tape can be provided that exhibits strong adhesive force not only at room temperature but also at high temperatures, and also has high holding power at high temperatures.

Claims

1. An adhesive composition comprising a copolymer (A), a crosslinking agent (B), and an aqueous medium, The copolymer (A) has structural units derived from monomers (a1), structural units derived from monomers having carboxyl groups (a2), and structural units derived from monomers having alkoxysilyl groups (a3). The monomer (a1) is composed of methyl (meth)acrylate, n-butyl (meth)acrylate, and 2-ethylhexyl (meth)acrylate. In the copolymer (A), the content of structural units derived from the monomer (a2) relative to 100 parts by mass of structural units derived from the monomer (a1) is 1.0 part by mass or more and 12 parts by mass or less. In the copolymer (A), the content of structural units derived from the monomer (a3) ​​relative to 100 parts by mass of structural units derived from the monomer (a1) is 0.010 parts by mass or more and 3.5 parts by mass or less. The crosslinking agent (B) contains one or more compounds selected from polycarbodiimide compounds, polyepoxide compounds, and polyisocyanate compounds. The content of the crosslinking agent (B) is 0.010 parts by weight or more and 10 parts by weight or less relative to 100 parts by weight of the copolymer (A). The copolymer (A) has structural units derived from a monomer (a4) having hydroxyl groups, wherein the content of structural units derived from said monomer (a4) in copolymer (A) is 0.10 parts by mass or more and 10 parts by mass or less per 100 parts by mass relative to structural units derived from said monomer (a1). The monomer (a4) containing hydroxyl groups is 2-hydroxyethyl (meth)acrylate.

2. The adhesive composition according to claim 1, wherein the copolymer (A) does not have structural units derived from compounds having multiple independent olefinic unsaturated double bonds.

3. The adhesive composition according to claim 1 or 2, wherein the copolymer (A) contains a total of more than 90% by mass of structural units from the monomer (a1), structural units from the monomer (a2), and structural units from the monomer (a3).

4. The adhesive composition according to claim 1 or 2, wherein the glass transition temperature of the copolymer (A) is above -80°C and below 30°C.

5. The adhesive composition according to claim 1 or 2, wherein the total content of dialkoxysilyl and trialkoxysilyl groups in all alkoxysilyl groups contained in the copolymer (A) is 80 mol% or more.

6. The adhesive composition according to claim 1 or 2, wherein the content of trialkoxysilyl groups in all alkoxysilyl groups contained in the copolymer (A) is 70 mol% or more.

7. The adhesive composition according to claim 1 or 2, wherein the crosslinking agent (B) is a polycarbodiimide compound.

8. The adhesive composition according to claim 7, wherein the carbodiimide equivalent of the crosslinking agent (B) is 150 or more and 1000 or less.

9. The adhesive composition according to claim 1 or 2, wherein the crosslinking agent (B) is a polyepoxide compound.

10. The adhesive composition according to claim 9, wherein the crosslinking agent (B) has an epoxy equivalent of 70 or more and 700 or less.

11. The adhesive composition according to claim 1 or 2, wherein the total content of the copolymer (A) and the crosslinking agent (B) in the non-volatile components is 50% by mass or more.

12. A copolymer dispersion for preparing the adhesive composition according to any one of claims 1 to 11, comprising copolymer (A) and an aqueous medium, The copolymer (A) has structural units derived from monomer (a1), structural units derived from monomer (a2) having a carboxyl group, and structural units derived from monomer (a3) ​​having an alkoxysilyl group. The monomer (a1) is composed of methyl (meth)acrylate, n-butyl (meth)acrylate, and 2-ethylhexyl (meth)acrylate. In the copolymer (A), the content of structural units derived from the monomer (a2) relative to 100 parts by mass of structural units derived from the monomer (a1) is 1.0 part by mass or more and 12 parts by mass or less. In the copolymer (A), the content of structural units derived from the monomer (a3) ​​relative to 100 parts by mass of structural units derived from the monomer (a1) is 0.010 parts by mass or more and 3.5 parts by mass or less. The copolymer (A) has structural units derived from a monomer (a4) having hydroxyl groups, wherein the content of structural units derived from said monomer (a4) in copolymer (A) is 0.10 parts by mass or more and 10 parts by mass or less per 100 parts by mass relative to structural units derived from said monomer (a1). The monomer (a4) containing hydroxyl groups is 2-hydroxyethyl (meth)acrylate.

13. A sleeve for formulating adhesive compositions, comprising a copolymer dispersion and a crosslinking agent (B), The copolymer dispersion contains copolymer (A) and an aqueous medium. The copolymer (A) has structural units derived from monomer (a1), structural units derived from monomer (a2) having a carboxyl group, and structural units derived from monomer (a3) ​​having an alkoxysilyl group. The monomer (a1) is composed of methyl (meth)acrylate, n-butyl (meth)acrylate, and 2-ethylhexyl (meth)acrylate. In the copolymer (A), the content of structural units derived from the monomer (a2) relative to 100 parts by mass of structural units derived from the monomer (a1) is 1.0 part by mass or more and 12 parts by mass or less. In the copolymer (A), the content of structural units derived from the monomer (a3) ​​relative to 100 parts by mass of structural units derived from the monomer (a1) is 0.010 parts by mass or more and 3.5 parts by mass or less. The crosslinking agent (B) contains one or more compounds selected from polycarbodiimide compounds, polyepoxide compounds, and polyisocyanate compounds. The content of the crosslinking agent (B) is 0.010 parts by weight or more and 10 parts by weight or less relative to 100 parts by weight of the copolymer (A). The copolymer (A) has structural units derived from a monomer (a4) having hydroxyl groups, wherein the content of structural units derived from said monomer (a4) in copolymer (A) is 0.10 parts by mass or more and 10 parts by mass or less per 100 parts by mass relative to structural units derived from said monomer (a1). The monomer (a4) containing hydroxyl groups is 2-hydroxyethyl (meth)acrylate.

14. A tape having a substrate and an adhesive layer formed on the surface of said substrate, The adhesive layer contains a cured product of the adhesive composition according to any one of claims 1 to 11.

15. An adhesive method using the tape of claim 14.

16. A method for manufacturing an adhesive tape, comprising: The process of applying the adhesive composition of any one of claims 1 to 11 onto a substrate, and The process of removing the aqueous medium from the adhesive composition applied to the substrate to form an adhesive layer.

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