JP7318883B2 - (Meth) acrylic resin composition - Google Patents

Description

The present invention relates to a (meth)acrylic resin composition.

Curable (meth)acrylic resin compositions are used, for example, as adhesives. Second-generation (meth)acrylic adhesives (hereinafter referred to as “SGA”) react with multiple types of (meth)acrylic monomer components, an organic peroxide as a polymerization initiator, and an organic peroxide. It is an adhesive that develops adhesive strength by adding a reducing agent that generates radicals, polymerizing, and curing. SGA is excellent in durability, transparency, and environment-friendliness, so it is used as an adhesive for structural members, an adhesive for automotive parts, an adhesive for electrical and electronic parts, an adhesive for flat panel displays, and the like.

For example, Patent Document 1 discloses a curable resin composition containing a (meth)acrylate monomer, titanium oxide having an average particle size of 5.0 μm or less, a polymerization initiator, a curing accelerator and an elastomer component. there is

Patent Document 2 describes (A) general formula (1): —OC(O)C(Ra)=CH ₂ (1)
(Wherein, Ra represents a hydrogen atom or an organic group having 1 to 20 carbon atoms) per molecule and at least two groups represented by the above general formula (1) at the end of the molecule and (B) a redox initiator.

Patent Document 3 discloses an elastomer component (A), a (meth)acrylic polymerizable monomer (B), a (meth)acrylic polymerizable monomer (C) other than component (B), a polymerization initiator ( Adhesive compositions containing D) and a reducing agent (E) are disclosed.

JP-A-2000-355647 JP 2006-299257 A JP 2014-88458 A

A curable (meth)acrylic resin composition develops adhesive strength in a short period of time and is an adhesive with excellent workability, but has the drawback of being inferior in fracture toughness. The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a novel (meth)acrylic resin composition having excellent fracture toughness.

［一般式（２）において、Ｒ^２１は、置換基を有していてもよい鎖状もしくは環状の炭化水素基を表す。Ｒ^２２は水素原子またはメチル基を表す。］
酸性基を有さない（メタ）アクリル系ビニルモノマー（ｂ）、および、
酸性基を有する（メタ）アクリル系ビニルモノマー（ｃ）を含有することを特徴とする。 The (meth)acrylic resin composition of the present invention comprises an A block having a structural unit derived from a (meth)acrylic vinyl monomer having an epoxy group and a B block having a structural unit represented by general formula (2). ABA-type triblock copolymer (a) containing

[In general formula (2), R ²¹ represents a chain or cyclic hydrocarbon group which may have a substituent. ^R22 represents a hydrogen atom or a methyl group. ]
(meth)acrylic vinyl monomer (b) having no acidic group, and
It is characterized by containing a (meth)acrylic vinyl monomer (c) having an acidic group.

When the (meth)acrylic resin composition of the present invention is cured, a phase structure in which the (a) component is phase-separated from the (meth)acrylic resin obtained by polymerizing the (b) component and the (c) component is obtained. . As a result, the cured product of the (meth)acrylic resin composition of the present invention has excellent fracture toughness.

The cured product of the (meth)acrylic resin composition of the present invention has excellent fracture toughness. As a result, it can be suitably used as an adhesive.

The graph which shows the fracture toughness of the hardened|cured material of a (meth)acrylic-type resin composition. The graph which shows the adhesive strength of a (meth)acrylic resin composition.

［一般式（２）において、Ｒ^２１は、置換基を有していてもよい鎖状もしくは環状の炭化水素基を表す。Ｒ^２２は水素原子またはメチル基を表す。］
酸性基を有さない（メタ）アクリル系ビニルモノマー（ｂ）、および、
酸性基を有する（メタ）アクリル系ビニルモノマー（ｃ）を含有することを特徴とする。 The (meth)acrylic resin composition of the present invention comprises an A block having a structural unit derived from a (meth)acrylic vinyl monomer having an epoxy group and a B block having a structural unit represented by general formula (2). ABA-type triblock copolymer (a) containing

[In general formula (2), R ²¹ represents a chain or cyclic hydrocarbon group which may have a substituent. ^R22 represents a hydrogen atom or a methyl group. ]
(meth)acrylic vinyl monomer (b) having no acidic group, and
It is characterized by containing a (meth)acrylic vinyl monomer (c) having an acidic group.

<(Meth)acrylic resin composition>
The (meth)acrylic resin composition of the present invention comprises an A block having a structural unit derived from a (meth)acrylic vinyl monomer having an epoxy group and a B block having a structural unit represented by general formula (2). ABA-type triblock copolymer (a) (hereinafter referred to as "(a) component") containing and, (meth)acrylic vinyl monomer (b) having no acidic group (hereinafter referred to as "(b) component") ) and a (meth)acrylic vinyl monomer (c) having an acidic group (hereinafter referred to as "component (c)").

In the present invention, "A block" can be rephrased as "A segment", for example, and "B block" can be rephrased as "B segment", for example. In the present invention, "vinyl monomer" means a monomer having a radically polymerizable carbon-carbon double bond in the molecule. A “structural unit derived from a (meth)acrylic vinyl monomer” is a structural unit in which the radically polymerizable carbon-carbon double bond of the (meth)acrylic vinyl monomer is polymerized to form a carbon-carbon single bond. Say. "(Meth)acrylic" means "acrylic or methacrylic, or both acrylic and methacrylic". "(Meth)acrylate" means "acrylate or methacrylate, or both acrylate and methacrylate". "(Meth)acryloyl" means "acryloyl or methacryloyl, or both acryloyl and methacryloyl".

((a) component)
The (a) component used in the present invention comprises an A block having a structural unit derived from a (meth)acrylic vinyl monomer having an epoxy group, and a B block having a structural unit represented by general formula (2). is an ABA-type triblock copolymer containing The component (a) is believed to impart toughness to the cured product of the present invention.

A Block The epoxy group-containing (meth)acrylic vinyl monomer constituting the A block is not particularly limited as long as it is a compound having a (meth)acryloyl group and an epoxy group. A (meth)acryloyl group means an acryloyl group (CH ₂ =CHCO-) or a methacryloyl group (CH ₂ =C(CH ₃ )CO-), or both an acryloyl group and a methacryloyl group.

(Meth)acrylic vinyl monomers having an epoxy group include, for example, glycidyl (meth)acrylate, 4-hydroxybutyl acrylate glycidyl ether, 3,4-epoxycyclohexylmethyl acrylate (e.g., Cychromer manufactured by Daicel Chemical Industries, Ltd.). A400”, etc.), 3,4-epoxycyclohexylmethyl methacrylate (eg, “Cychromer M100” manufactured by Daicel Chemical Industries, Ltd.), and the like. The (meth)acrylic vinyl monomer having an epoxy group may be used alone or in combination of two or more.

The content of structural units derived from a (meth)acrylic vinyl monomer having an epoxy group in the A block is preferably 10% by mass or more, more preferably 25% by mass or more, preferably 90% by mass or less, and 75% by mass. The following are more preferred.

［一般式（１）において、Ｒ^１１は、置換基を有していてもよいアルキレン基またはアリーレン基を表す。Ｒ^１２は水素原子またはメチル基を表す。］ The structural unit derived from the (meth)acrylic vinyl monomer having an epoxy group in the A block is preferably a structural unit represented by general formula (1).

[In general formula (1), R ¹¹ represents an optionally substituted alkylene group or arylene group. ^R12 represents a hydrogen atom or a methyl group. ]

R ¹¹ is preferably an alkylene group or arylene group having 1 to 12 carbon atoms, more preferably an alkylene group or arylene group having 1 to 6 carbon atoms.

The content of the structural unit represented by general formula (1) in the A block is preferably 10% by mass or more, more preferably 25% by mass or more, preferably 90% by mass or less, and more preferably 75% by mass or less.

The A block may have structural units other than the structural unit represented by formula (1). Other structural units that can be contained in the A block are both (meth)acrylic vinyl monomers that form the structural unit represented by formula (1) and (meth)acrylic vinyl monomers that form the B block described later. There is no particular limitation as long as it is formed from a (meth)acrylic vinyl monomer that can be copolymerized with. The (meth)acrylic vinyl monomers capable of forming other structural units of the A block may be used alone, or two or more of them may be used in combination. The content of structural units other than the structural unit represented by formula (1) in the A block is preferably 10% by mass or more, more preferably 25% by mass or more, and preferably 90% by mass or less. % by mass or less is more preferable.

(Meth)acrylic vinyl monomers that can form other structural units of the A block include
The same ones as the (meth)acrylic vinyl monomer (b) having no acidic group to be described later can be exemplified. Among these, it is preferable to use a (meth)acrylate having a chain alkyl group (straight-chain alkyl group or branched-chain alkyl group).

The chain alkyl group of the (meth)acrylate having a chain alkyl group is preferably a chain alkyl group having 1 to 10 carbon atoms, more preferably a straight chain alkyl group having 1 to 10 carbon atoms. A linear alkyl group of 1 or more and less than 6 is more preferable. Specific examples of (meth)acrylates having a chain alkyl group include methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, sec-butyl (meth)acrylate, tert-butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate and the like.

In the present invention, a block having a glycidyl (meth)acrylate structural unit and a methyl (meth)acrylate structural unit is preferable as the A block.

［一般式（２）において、Ｒ^２１は、置換基を有していてもよい鎖状もしくは環状の炭化水素基を表す。Ｒ^２２は水素原子またはメチル基を表す。］ B Block The B block is a polymer block having a structural unit represented by general formula (2).

[In general formula (2), R ²¹ represents a chain or cyclic hydrocarbon group which may have a substituent. ^R22 represents a hydrogen atom or a methyl group. ]

R ²¹ is a chain or cyclic hydrocarbon group, such as a chain alkyl group (straight-chain alkyl group or branched-chain alkyl group), a cyclic alkyl group (monocyclic structure), an aromatic ring group, and the like. can be done. R ²¹ is preferably a hydrocarbon group having 6 to 12 carbon atoms, a chain alkyl group having 6 to 12 carbon atoms (straight-chain alkyl group or branched alkyl group), It is more preferably at least one selected from the group consisting of the following cyclic alkyl groups (monocyclic structures) and aromatic ring groups having 6 to 12 carbon atoms.

The chain alkyl group of the (meth)acrylate having a chain alkyl group includes a hexyl group (C6), a heptyl group (C7), an octyl group (C8), a nonyl group (C9), a decyl group (C10), and undecyl. group (C11), dodecyl group (C12) and the like.

Specific examples of (meth)acrylates having a chain alkyl group that can constitute the B block include hexyl (meth)acrylate, heptyl (meth)acrylate, octyl (meth)acrylate, nonyl (meth)acrylate, and decyl (meth)acrylate. , undecyl (meth)acrylate, dodecyl (meth)acrylate and the like.

The cyclic alkyl group of the (meth)acrylate having the cyclic alkyl group is preferably a cyclic alkyl group having 6 to 12 carbon atoms. Specific examples of (meth)acrylates having a cyclic alkyl group that can constitute the B block include cyclohexyl (meth)acrylate, methylcyclohexyl (meth)acrylate, cyclododecyl (meth)acrylate and the like.

The aromatic ring of the (meth)acrylate having the aromatic ring group is preferably an aromatic ring having 6 to 12 carbon atoms. Specific examples of (meth)acrylates having an aromatic ring group that can constitute the B block include benzyl (meth)acrylate, phenyl (meth)acrylate, phenoxyethyl (meth)acrylate and the like.

The content of the structural unit represented by the general formula (2) in the B block is preferably 50% by mass or more, more preferably 75% by mass or more, still more preferably 90% by mass or more, and preferably 100% by mass or less, It is more preferably 95% by mass or less. It is also preferable that the B block consists only of structural units represented by general formula (2).

It is preferable that the B block substantially does not contain structural units derived from the epoxy group-containing (meth)acrylic vinyl monomer contained in the block A.

ABA Triblock Copolymer The content of A block in the ABA triblock copolymer is preferably 10% by mass or more, more preferably 30% by mass or more, and still more preferably 100% by mass of the entire block copolymer. is 50% by mass or more, preferably 90% by mass or less, more preferably 75% by mass or less, and even more preferably 60% by mass or less.

When the ABA type triblock copolymer has A1 block and A2 block as A block, the mass ratio (A1/A2) thereof is preferably 0.4 or more, more preferably 0.7 or more, further preferably It is 0.8 or more, preferably 2.3 or less, more preferably 1.5 or less, and still more preferably 1.2 or less.

The mass ratio of A block to B block (A block/B block) in the ABA type triblock copolymer is preferably 10/90 or more, more preferably 30/70 or more, and still more preferably 50/50 or more. It is preferably 90/10 or less, more preferably 75/25 or less, still more preferably 60/40 or less. If the mass ratio of the A block and the B block is within the above range, the obtained cured product has better fracture toughness.

The molar concentration (mol/g) of epoxy groups possessed by the ABA-type triblock copolymer is preferably 0.0005 or more, more preferably 0.001 or more, preferably 0.004 or less, and more preferably 0.003 or less. . This is because, when the molar concentration (mol/g) of the epoxy groups is within the above range, a phase separation structure is likely to be formed in the obtained cured product.

The molecular weight of the ABA-type triblock copolymer is measured by gel permeation (hereinafter referred to as "GPC") method. The weight average molecular weight (Mw) of the triblock copolymer is preferably 30,000 or more, more preferably 40,000 or more, still more preferably 50,000 or more, and preferably 500,000 or less, more preferably 300. ,000 or less, more preferably 100,000 or less. If the weight average molecular weight is within the above range, the fracture toughness of the resulting cured product will be better.

The molecular weight distribution (PDI) of the ABA-type triblock copolymer is preferably 3.0 or less, more preferably 2.0 or less. In the present invention, the molecular weight distribution (PDI) is determined by (weight average molecular weight (Mw) of block copolymer)/(number average molecular weight (Mn) of block copolymer). The smaller the PDI, the narrower the width of the molecular weight distribution of the copolymer, and the more uniform the molecular weight of the copolymer. That is, the lower limit of PDI is 1.0. When the molecular weight distribution (PDI) of the block copolymer exceeds 3.0, it includes those with small molecular weights and those with large molecular weights.

Method for producing ABA-type triblock copolymer The method for producing the ABA-type triblock copolymer is as follows. ) The AB block may be produced by polymerizing the acrylic vinyl monomer, and the AB block may be further polymerized with the (meth)acrylic vinyl monomer of the A block to produce the ABA block; or after the AB block is produced. , the B blocks of the AB blocks may be coupled to produce the ABA blocks.

Although the polymerization method is not particularly limited, living radical polymerization is preferred. That is, the block copolymer is preferably polymerized by living radical polymerization. In the conventional radical polymerization method, not only initiation reaction and propagation reaction but also termination reaction and chain transfer reaction cause deactivation of propagating terminal, and tend to result in a mixture of polymers with various molecular weights and non-uniform compositions. On the other hand, the living radical polymerization method maintains the simplicity and versatility of the conventional radical polymerization method. It is preferable in that it is easy to precisely control and manufacture a polymer with a uniform composition.

When the ABA-type block copolymer is produced by a living radical polymerization method, specifically, the (meth)acrylic vinyl monomer constituting the first block _A1 of the two A blocks is polymerized to obtain the first A step of polymerizing the A ₁ block of 1; after polymerizing the first A ₁ block, polymerizing a (meth)acrylic vinyl monomer constituting the B block to polymerize the B block; After polymerization, a (meth)acrylic vinyl monomer constituting the second _A2 block of the two A blocks is polymerized to polymerize the second _A2 block. be done.

Living radical polymerization methods include a method using a transition metal catalyst (ATRP method); a method using a sulfur-based reversible chain transfer agent (RAFT method); There is a method such as a method (TERP method). Since the ATRP method uses an amine-based complex, it may not be possible to use it without protecting the acidic group of the vinyl monomer having an acidic group. In the RAFT method, when a variety of monomers are used, it is difficult to obtain a low molecular weight distribution, and problems such as sulfur odor and coloration may occur. Among these methods, it is preferable to use the TERP method from the viewpoint of the diversity of usable monomers, molecular weight control in the high molecular region, uniform composition, or coloring.

The TERP method is a method of polymerizing a radically polymerizable compound (vinyl monomer) using an organic tellurium compound as a chain transfer agent. 2004/072126 and methods described in WO 2004/096870.

((b) component)
The component (b) used in the present invention is a (meth)acrylic vinyl monomer other than the component (c) described below, that is, a (meth)acrylic vinyl monomer having no acidic group. Component (b) may be used alone or in combination of two or more.

Specific examples of component (b) include (meth)acrylates having chain alkyl groups (straight-chain alkyl groups or branched-chain alkyl groups), (meth)acrylates having cyclic alkyl groups, and (meth)acrylates having a polycyclic structure. ) acrylates, (meth)acrylates having an aromatic group, (meth)acrylates having a hydroxy group, (meth)acrylates having an alkoxy group, etc., preferably linear alkyl having 1 to 6 carbon atoms and a (meth)acrylate having a branched-chain alkyl group having 3 to 6 carbon atoms, more preferably a straight-chain alkyl group having 1 carbon atom. It is a (meth)acrylate having a straight-chain alkyl group of 6 or more.

As the (meth)acrylate having a straight-chain alkyl group, a (meth)acrylate having a straight-chain alkyl group having 1 to 20 carbon atoms in the straight-chain alkyl group is preferable, and the straight-chain alkyl group has 1 or more carbon atoms. More preferred are (meth)acrylates with linear alkyl groups that are less than 6. Examples of (meth)acrylates having a linear alkyl group include methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, n-butyl (meth)acrylate, n-hexyl (meth)acrylate, n-octyl (meth)acrylate, n-nonyl (meth)acrylate, n-decyl (meth)acrylate, n-lauryl (meth)acrylate, n-stearyl (meth)acrylate and the like.

The (meth)acrylate having a branched-chain alkyl group is preferably a (meth)acrylate having a branched-chain alkyl group having 3 to 20 carbon atoms in the branched-chain alkyl group, and the branched-chain alkyl group having 3 or more carbon atoms. (Meth)acrylates with branched alkyl groups that are less than 6 are preferred. Examples of (meth)acrylates having a branched alkyl group include isopropyl (meth)acrylate, isobutyl (meth)acrylate, sec-butyl (meth)acrylate, tert-butyl (meth)acrylate, isooctyl (meth)acrylate, 2- ethylhexyl (meth)acrylate, isononyl (meth)acrylate, isodecyl (meth)acrylate and the like.

The (meth)acrylate having a cyclic alkyl group is preferably a (meth)acrylate having a cyclic alkyl group having 6 to 12 carbon atoms. Cyclic alkyl groups include cyclic alkyl groups having a monocyclic structure (eg, cycloalkyl groups). Specific examples of (meth)acrylates having a cyclic alkyl group with a monocyclic structure include cyclohexyl (meth)acrylate, methylcyclohexyl (meth)acrylate, cyclododecyl (meth)acrylate and the like.

The (meth)acrylate having a polycyclic structure is preferably a (meth)acrylate having a polycyclic structure with 6 to 12 carbon atoms. Polycyclic structures include cyclic alkyl groups having a bridged ring structure (eg, adamantyl, norbornyl, isobornyl groups). Specific examples of (meth)acrylates having a polycyclic structure include isobornyl (meth)acrylate, dicyclopentenyloxyethyl (meth)acrylate, dicyclopentenyloxyethyl (meth)acrylate, 2-methyl-2-adamantyl (Meth)acrylate, 2-ethyl-2-adamantyl (meth)acrylate and the like.

The (meth)acrylate having an aromatic group is preferably a (meth)acrylate having an aromatic group having 6 to 12 carbon atoms. Aromatic groups include aryl groups, alkylaryl groups, aralkyl groups, aryloxy groups, aryloxyalkyl groups, alkylaryloxy groups, aralkyloxy groups and the like, particularly phenyl groups, benzyl groups, tolyl groups and phenoxyethyl groups. groups are preferred. Specific examples of (meth)acrylates having an aromatic group include benzyl (meth)acrylate, phenyl (meth)acrylate, phenoxyethyl (meth)acrylate and the like.

Examples of (meth)acrylates having a hydroxy group include 2-hydroxyethyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 6- Hydroxyhexyl (meth)acrylate, 8-hydroxyoctyl (meth)acrylate, 10-hydroxydecyl (meth)acrylate, 12-hydroxylauryl (meth)acrylate and the like.

Examples of (meth)acrylates having an alkoxy group include methoxyethyl (meth)acrylate and ethoxyethyl (meth)acrylate.

The amount of component (b) is preferably 50% to 99% by mass, and preferably 70% to 95% by mass, based on the total 100% by mass of components (a) to (c) in terms of adhesive strength at high temperatures. % is more preferred.

(Component (c))
Component (c) used in the present invention is a (meth)acrylic vinyl monomer having an acidic group. Examples of the acidic group include a carboxy group (--COOH), a sulfonic acid group (--SO ₃ H), a phosphoric acid group (--OPO ₃ H ₂ ), a phosphonic acid group (--PO ₃ H ₂ ), a phosphinic acid group (-- PO ₂ H ₂ ), preferably a carboxy group (--COOH). (c) A component can be used individually or in combination of 2 or more types.

When the (meth)acrylic resin composition of the present invention is cured, the acidic group of the component (c) reacts with the epoxy group of the (a) ABA type block copolymer, and phase separation occurs in the resulting cured product. It is thought that the structure becomes easier to form.

Specific examples of the component (c) include (meth)acrylic acid; a monomer having a carboxy group, such as a monomer obtained by reacting a hydroxyalkyl (meth)acrylate with an acid anhydride such as maleic anhydride, succinic anhydride, or phthalic anhydride. (Meth)acrylate; (meth)acrylate having a sulfonic acid group such as ethyl sulfonate (meth)acrylate; (meth)acrylate having a phosphoric acid group such as 2-(phosphonooxy)ethyl (meth)acrylate; preferably at least one selected from the group consisting of (meth)acrylic acid, (meth)acrylates having a carboxyl group and (meth)acrylates having a phosphoric acid group, more preferably (meth)acrylic acid .

((d) curing agent)
The (meth)acrylic resin composition of the present invention preferably contains (d) a curing agent (hereinafter sometimes referred to as "component (d)"). (d) The curing agent is preferably an organic peroxide. The curing agent (d) generates radicals when heated to initiate the polymerization reaction of the components (b) and (c). Specific examples of component (d) include cumene hydroperoxide, p-menthane hydroperoxide, diisopropylbenzene hydroperoxide, 1,1,3,3-tetramethylbutyl hydroperoxide, t-butyl hydroperoxide, t-hexyl hydroperoxide, t-amyl hydroperoxide, 2,5-dimethylhexane-2,5-dihydroperoxide and the like.

((e) reducing agent)
The (meth)acrylic resin composition of the present invention preferably contains (e) a reducing agent (hereinafter sometimes referred to as "component (e)"). By using a combination of (d) a curing agent and (e) a reducing agent, radicals are generated at a low temperature to a normal temperature. By using the (d) component and the (e) component together, the (meth)acrylic resin composition of the present invention can be cured at room temperature.

Component (e) includes transition metal salts, thiourea compounds, and the like. Specific examples of transition metal salts include vanadyl acetylacetonate, vanadium acetylacetonate, copper naphthenate, and cobalt naphthenate. Specific examples of thiourea compounds include thiourea, ethylenethiourea, N,N'-dimethylthiourea, N,N'-diethylthiourea, N,N'-dipropylthiourea, and N,N'-di-n-butylthiourea. , N,N'-dilaurylthiourea, N,N'-diphenylthiourea, trimethylthiourea, 1-acetyl-2-thiourea, 1-benzoyl-2-thiourea and the like.

(other ingredients)
The (meth)acrylic resin composition of the present invention may contain other components as long as the effects of the present invention are not impaired. Specific examples of other components include radically polymerizable monomers other than (meth)acrylic, such as vinyl monomers, various additives (antioxidants, plasticizers, ultraviolet absorbers, silane coupling agents, antifoaming agents, agents, polymerization inhibitors, inorganic fine particles, etc.). In order to shorten the curing time, a tertiary compound such as N,N-dimethyl-p-toluidine, N,N-diisopropyl-p-toluidine, N,N-di(2-hydroxyethyl)-p-toluidine, etc. A class amine compound, a phosphorus compound such as triphenylphosphine, and the like may be added. Furthermore, in order to further improve the strength of the cured product, thermal polymerization initiators (peroxides other than component (d), azo compounds, etc.) and photopolymerization initiators (1-hydroxycyclohexylphenyl ketone, etc.) may be added. good.

In the (meth)acrylic resin composition of the present invention, the amount of component (a) is preferably 0.1% by mass or more, preferably 1% by mass, based on the total 100% by mass of components (a) to (c). The above is more preferable, 20% by mass or less is preferable, and 10% by mass or less is more preferable. This is because, by setting the amount of component (a) to be 0.1% by mass to 20% by mass, the fracture toughness of the obtained cured product is improved without impairing the properties of the cured product.

In the (meth)acrylic resin composition of the present invention, the molar ratio ((b)/(c)) of component (b) to component (c) is preferably 80/20 or more, more preferably 90/10 or more. is more preferable, 99/1 or less is preferable, and 98/2 or less is more preferable. By setting the ratio of the component (b) to the component (c) within the above range, it becomes easier to form a phase-separated structure in the obtained cured product.

In the (meth)acrylic resin composition of the present invention, the ratio of the number of moles of epoxy groups possessed by component (a) to the number of moles of acid groups possessed by component (c) (epoxy group/acidic group) is 0.1. 0.15 or more is more preferable, 0.6 or less is preferable, and 0.5 or less is more preferable. If the ratio of the number of moles of epoxy groups in component (a) to the number of moles of acid groups in component (c) (epoxy group/acid group) is within the above range, a phase separation structure is formed in the resulting cured product. easier to be

In the (meth)acrylic resin composition of the present invention, the amount of component (d) is preferably 0.001 parts by mass or more when the total amount of components (b) to (c) is 100 parts by mass. 0.002 parts by mass or more is more preferable, 10 parts by mass or less is preferable, and 1 part by mass or less is more preferable. When the amount of component (d) is within the above range, the curing reaction can be carried out efficiently, and the fracture toughness of the obtained cured product is improved.

In the (meth)acrylic resin composition of the present invention, the blending amount of component (e) is preferably 0.001 parts by mass or more when the total amount of components (b) to (c) is 100 parts by mass. 0.002 parts by mass or more is more preferable, 10 parts by mass or less is preferable, and 1 part by mass or less is more preferable. When the amount of component (e) is within the above range, the curing reaction can be carried out efficiently, and the fracture toughness of the obtained cured product is improved.

In the (meth)acrylic resin composition of the present invention, the content of other components is not particularly limited. Part by mass or less is more preferable.

(Method for producing (meth)acrylic resin composition)
When the (meth)acrylic resin composition of the present invention contains components (a) to (e), the components (d) and (e) must be produced in a separate two-component state so as not to mix. is preferred. By keeping the components (d) and (e) from mixing, it is possible to prevent the (meth)acrylic resin composition from curing at room temperature. Specifically, it is a two-component type consisting of a first component in which component (d) is blended with components (a) to (c) and a second component in which component (e) is blended in components (a) to (c). Alternatively, there may be mentioned a two-component type consisting of a first component in which component (e) is blended with components (a) to (c) and a second component comprising component (d).

As a method for producing the (meth)acrylic resin composition of the present invention, first, components (a) to (c) are mixed and stirred to produce an abc mixed solution. It is also preferable to mix the components (a) to (c) while heating. The temperature for mixing components (a) to (c) is, for example, preferably 40° C. or higher, more preferably 80° C. or higher, preferably 120° C. or lower, and more preferably 110° C. or lower. The stirring time is not particularly limited, but is preferably 1 minute or longer and preferably 180 minutes or shorter.

The components (a) to (c) are mixed by dissolving or finely dispersing the ABA-type block copolymer (a) in the liquid (meth)acrylic vinyl monomers as components (b) and (c). It is preferable to go to After the ABA block copolymer (a) is dissolved or finely dispersed, the abc mixed solution is cooled to room temperature. The components (a) to (c) may be mutually dissolved by applying a shearing force using a planetary mixer or the like to produce an abc mixed solution. Next, the abc mixed liquid cooled to room temperature is divided into two parts, one of which is mixed with the component (d) to prepare the first part, and the other part of which is mixed with the component (e) to prepare the second part. .

<Cured product>
The cured product of the present invention is obtained by curing the (meth)acrylic resin composition of the present invention. The curing reaction can be carried out, for example, by adding (d) a curing agent to a mixture of components (a) to (c) and heating and curing, or by combining (d) a curing agent and (e) a reducing agent. A method of hardening at room temperature can be mentioned.

In the method of using (d) a curing agent and (e) a reducing agent in combination, for example, the first agent containing the (d) component and the second agent containing the (e) component are mixed to form a (meth)acrylic The system resin composition is cured at room temperature. When the first agent and the second agent are mixed, the component (d) contained in the first agent and the component (e) contained in the second agent generate radicals through an oxidation-reduction reaction. By generating radicals, the polymerization reaction between components (b) and (c) proceeds to obtain a cured product. The curing reaction can be carried out at room temperature, but if necessary, the curing reaction may be accelerated by heating.

The cured product of the present invention preferably has a structure in which the (a) component is phase-separated from the (meth)acrylic resin obtained by polymerizing the (b) component and the (c) component. By having such a phase-separated structure, it is considered that the fracture toughness of the obtained cured product is increased. As the phase separation structure, for example, submicron to micron-sized spherical component (a) is separated in a (meth)acrylic resin (matrix resin) obtained by polymerizing components (b) and (c). The linear (a) component with a size of several tens of nanometers is separated in a macrophase-separated structure, or in a (meth)acrylic resin (matrix resin) obtained by polymerizing components (b) and (c). A microphase-separated structure is observed.

Since the curable (meth)acrylic resin composition of the present invention can be cured at room temperature, it can be suitably used as an adhesive. Specifically, it is suitably used as an adhesive for structural members, an adhesive for automobile parts, an adhesive for electrical and electronic parts, an adhesive for flat panel displays, and the like.

The present invention includes an adherend comprising two or more adherends adhered with a cured product of the (meth)acrylic resin composition of the present invention. For example, the adhesive is applied by applying a mixture of two agents to one of two adherends and bonding it to the other, or by bonding together adherends to which the two agents are separately applied. can be manufactured.

Hereinafter, the present invention will be described in more detail based on specific examples. The present invention is by no means limited to the following examples, and can be modified as appropriate without changing the gist of the invention.

[Evaluation method]
(Polymerization rate)
¹ H-NMR was measured (solvent: deuterated chloroform, internal standard: tetramethylsilane) using a nuclear magnetic resonance (NMR) spectrometer (manufactured by Bruker, model: AVANCE500 (frequency: 500 MHz)). For the obtained NMR spectrum, the integration ratio of the peaks of the vinyl group derived from the monomer and the peak of the ester side chain derived from the polymer was determined to calculate the polymerization rate of the monomer.

(Weight average molecular weight (Mw) and molecular weight distribution (PDI))
It was determined by gel permeation chromatography (GPC) using a high-performance liquid chromatograph (manufactured by Tosoh, model: HLC-8320). Two columns of TSKgel Super Multipore HZ-H (Φ4.6×150, TOSOH Co. Tokyo, Japan) (manufactured by Tosoh Corporation) were used as columns, tetrahydrofuran was used as a mobile phase, and a differential refractometer was used as a detector. The measurement conditions were a column temperature of 40° C., a sample concentration of 10 mg/mL, a sample injection amount of 10 μL, and a flow rate of 0.35 mL/min. Polystyrene (molecular weight 2,890,000, 1,090,000, 706,000, 427,000, 190,000, 96,400, 37,900, 10,200, 2,630, 440) was used as a standard Then, a calibration curve (calibration curve) was prepared, and the weight average molecular weight (Mw) and number average molecular weight (Mn) were measured. A molecular weight distribution (PDI=Mw/Mn) was calculated from these measured values.

The abbreviations of raw materials used in the experimental examples of the present invention are as follows.
MMA: methyl methacrylate GMA: glycidyl methacrylate LMA: lauryl methacrylate (dodecyl methacrylate)
BTEE: ethyl-2-methyl-2-n-butyltheranyl-propionate DBDT: dibutyl ditelluride ADVN: 2,2'-azobis-2,4-dimethylvaleronitrile PMA: propylene glycol monomethyl ether acetate MeOH: methanol

<Production of ABA type block copolymer>
(Synthesis Example 1): ABA-type block copolymer No. 1 by living radical polymerization. Synthesis of 1 40.00 g of GMA, 16.00 g of MMA, 0.960 g of BTEE, 0.590 g of DBDT, 0.159 g of ADVN, and 104.00 g of PMA, which had been previously purged with argon, were placed in a 500 mL reactor equipped with a stirrer and purged with argon. reacted over time. The polymerization rate was 97%.

9.60 g of LMA, 17.60 g of toluene, and 0.037 g of ADVN, which had been previously replaced with argon, were added to this reaction solution and reacted at 50° C. for 1 hour. Next, 19.20 g of LMA previously replaced with argon and 5.60 g of toluene were additionally added and reacted at 50° C. for 1 hour. Next, 67.20 g of LMA, 100.80 g of toluene, and 0.159 g of ADVN, which had been replaced with argon in advance, were additionally added and reacted at 50° C. for 40 hours. The polymerization rate was 96%.

40.00 g of GMA, 16.00 g of MMA, 30.00 g of PMA, and 0.159 g of ADVN, which had been replaced with argon in advance, were added to this reaction solution and reacted at 50° C. for 24 hours. The polymerization rate was 96%. In addition, the monomers in the first and second stages of polymerization remaining in the reaction liquid were also polymerized, and the polymerization rate of the monomers in the first and second polymerization stages remaining in these reaction liquids was 100%. rice field.

After completion of the reaction, the reaction solution was diluted with toluene and poured into methanol while stirring. The precipitated polymer was filtered by suction and dried to obtain ABA type block copolymer No. 1. got 1. ABA type block copolymer No. The Mw of 1 was 86,565 and the PDI was 1.73.

(Synthesis Example 2): ABA-type block copolymer No. 2 produced by living radical polymerization. Synthesis of 2 16.00 g of GMA, 40.00 g of MMA, 0.960 g of BTEE, 0.590 g of DBDT, 0.159 g of ADVN, and 104.00 g of PMA, which had been previously purged with argon, were placed in a 500 mL reactor equipped with a stirrer and purged with argon. reacted over time. The polymerization rate was 97%.

9.60 g of LMA, 17.60 g of toluene, and 0.037 g of ADVN, which had been previously replaced with argon, were added to this reaction solution and reacted at 50° C. for 1 hour. Next, 19.20 g of LMA previously replaced with argon and 5.60 g of toluene were additionally added and reacted at 50° C. for 1 hour. Next, 67.20 g of LMA, 100.80 g of toluene, and 0.159 g of ADVN, which had been replaced with argon in advance, were additionally added and reacted at 50° C. for 40 hours. The polymerization rate was 96%.

16.00 g of GMA, 40.00 g of MMA, 30.00 g of PMA, and 0.159 g of ADVN, which had been replaced with argon in advance, were added to this reaction solution and reacted at 50° C. for 24 hours. The polymerization rate was 96%. In addition, the monomers in the first and second stages of polymerization remaining in the reaction liquid were also polymerized, and the polymerization rate of the monomers in the first and second polymerization stages remaining in these reaction liquids was 100%. rice field. After completion of the reaction, the reaction solution was diluted with toluene and poured into methanol while stirring. The precipitated polymer was filtered by suction and dried to obtain ABA type block copolymer No. 1. got 2. ABA type block copolymer No. The Mw of 2 was 63,123 and the PDI was 1.50.

ABA type block copolymer No. 1 to No. Table 1 shows the production conditions and properties of No. 2.

<Production of curable (meth)acrylic resin composition>
Using methyl methacrylate (MMA) as the component (b) and methacrylic acid (MAA) as the component (c), they are mixed in a molar ratio of MMA:MAA=97:3 to obtain a methacrylate monomer mixture. rice field. The ABA type block copolymer (a) obtained above was added to this methacrylate monomer mixture, and the mixture was stirred at 23° C. for 2 hours. The mixing ratio of the methacrylate monomer mixture and the ABA block copolymer was set to methacrylate monomer mixture:ABA block copolymer=95:5 (mass ratio). After confirming that the ABA block copolymer (a) was dissolved in the methacrylate monomer mixture, the mixture was cooled to room temperature to obtain an abc mixture of components (a) to (c).

The abc solution obtained above was divided into two, and cumene hydroperoxide was added to one of the two as the component (d) to prepare the first agent. To the other, trimethylthiourea was added as component (e) to prepare a second agent. The amount of component (d) added was 0.005 part by mass per 100 parts by mass of the total amount of components (b) to (c). The amount of component (e) added was 0.011 part by mass per 100 parts by mass of the total amount of components (b) to (c).

The obtained first agent and second agent were blended in a mass ratio of 1:1 to obtain (meth)acrylic resin composition No. 1. 1 to No. 2 was prepared. For comparison, the (meth)acrylic resin composition No. 1 containing no ABA type block copolymer was used. 3 was prepared. (Meth) acrylic resin composition No. 1 to No. The composition of No. 3 is shown in Table 2.

<Fracture toughness test>
The obtained (meth)acrylic resin composition No. 1 to No. 3 was poured into a mold and cured at normal temperature (23° C.) to form a specimen for fracture toughness test. A fracture toughness test was performed according to ASTM D5045-93. The results are shown in Table 3 and FIG. KIc is fracture toughness that means resistance to crack progression, and the larger the value, the higher the fracture toughness. From the results of FIG. 1, the (meth)acrylic resin composition No. 1 to No. 2 has excellent fracture toughness.

<Adhesion strength test>
(Meth) acrylic resin composition No. 1 to No. 3 was applied to an aluminum plate (200 mm×25 mm×0.5 mm), and the two aluminum plates were bonded together. A spacer of 120 μm was sandwiched between the adhesive layers. After the application, it was allowed to stand at room temperature (23° C.) for 8 hours and then treated at 60° C. for 4 hours. 1 to No. The curing reaction of No. 3 was performed to prepare a test piece for the T-type peel test. A T-type peel test was performed using a mechanical testing machine, Autograph AGS-J, manufactured by Shimadzu Corporation, at a head speed of 100 mm/min. Table 4 and FIG. 2 show the results of T-peel adhesion strength. From the results of FIG. 2, the (meth)acrylic resin composition No. 1 to No. 2 shows excellent adhesive strength.

Claims (13)

An ABA triblock copolymer (a ),

[In general formula (2), R ²¹ represents a chain or cyclic hydrocarbon group having 6 or more and 12 or less carbon atoms. ^R22 represents a hydrogen atom or a methyl group. ]
containing a (meth)acrylic vinyl monomer (b) having no acidic group and a (meth)acrylic vinyl monomer (c) having an acidic group,
The ratio of the component (b) and the component (c) is 80/20 or more and 99/1 or less in molar ratio ((b)/(c)),
The epoxy group molar concentration (mol/g) of the ABA triblock copolymer is 0.0005 or more and 0.004 or less,
The ratio of the number of moles of the epoxy groups in the component (a) to the number of moles of the acid groups in the component (c) (epoxy group/acid group) is 0.1 or more and 0.6 or less. (Meth)acrylic resin composition. The (meth)acrylic resin composition according to claim 1, which contains a curing agent (d). 3. The (meth)acrylic resin composition according to claim 1, which contains a reducing agent (e). Consisting of a first agent and a second agent,
The first agent is the ABA triblock copolymer (a),
the (meth)acrylic vinyl monomer (b) having no acidic group;
containing (c) the (meth)acrylic vinyl monomer having an acidic group, and (d) a curing agent,
The second agent is the ABA triblock copolymer (a),
the (meth)acrylic vinyl monomer (b) having no acidic group;
2. The (meth)acrylic resin composition according to claim 1, comprising (c) the (meth)acrylic vinyl monomer having an acidic group and (e) a reducing agent. The (meth)acrylic resin composition according to any one of claims 1 to 4, wherein the content of the structural unit represented by general formula (2) in the B block is 50% by mass to 100% by mass. . The (meth) according to any one of claims 1 to 5, wherein the content of structural units derived from a (meth)acrylic vinyl monomer having an epoxy group in the A block is 10% by mass to 90% by mass. Acrylic resin composition. The structural unit derived from a (meth)acrylic vinyl monomer having an epoxy group in the A block is a structural unit represented by the general formula (1) (meth) according to any one of claims 1 to 6 ) acrylic resin composition.

[In general formula (1), R ¹¹ represents an optionally substituted alkylene group or arylene group. ^R12 represents a hydrogen atom or a methyl group. ] The mass ratio (A block/B block) of the A block and the B block in the ABA type triblock copolymer (a) is 10/90 to 90/10, according to any one of claims 1 to 7 The (meth)acrylic resin composition described. The (meth)acrylic resin composition according to any one of claims 1 to 8, wherein the ABA triblock copolymer (a) has a molecular weight distribution (PDI) of 1.0 to 3.0. The (meth)acrylic vinyl monomer having no acidic group (b) has a (meth)acrylate having a linear alkyl group having 1 to 6 carbon atoms and a branched alkyl group having 3 to 6 carbon atoms. The (meth)acrylic resin composition according to any one of claims 1 to 9, which is at least one selected from the group consisting of (meth)acrylates. The (meth)acrylic resin composition according to any one of claims 1 to 10, wherein the (meth)acrylic vinyl monomer (c) having an acidic group is (meth)acrylic acid. A cured product of the (meth)acrylic resin composition according to any one of claims 1 to 11. 13. An adherend comprising two or more adherends adhered with the cured product of the (meth)acrylic resin composition according to claim 12.

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