JP2020143237A - Adhesive composition - Google Patents

Abstract

To provide an adhesive composition which is excellent in adhesion between metal and a resin, and is excellent in stress relaxation and heat resistance.SOLUTION: An adhesive composition contains an acrylic rubber having at least one functional group selected from the group consisting of a carboxyl group, a hydroxyl group and an epoxy group, a thermosetting component that reacts with the functional group and a curing accelerator, in which the acrylic rubber contains a copolymer of at least one of acrylate and its derivative and at least one of acrylonitrile and its derivative, and a ratio of a peak area of absorbance due to a carbonyl group of the acrylate at a wave number of 1740 cm-1 to a peak area of absorbance due to a nitrite group of the acrylonitrile at a wave number of 2240 cm-1 which are measured by ATR method using a Fourier transform infrared spectrophotometer (FT-IR) is 0.001 or more and 0.02 or less.SELECTED DRAWING: None

Description

The present invention relates to an adhesive composition.

Examples of the method for manufacturing a composite part of metal and resin include insert molding and hot press molding. Examples of the method of joining the metal and the resin when manufacturing the composite part include the methods described in Patent Documents 1 to 3.

In Patent Document 1, a metal member is surface-treated by physical or chemical treatment to roughen the surface, and the molten resin is brought into contact with the roughened surface to solidify the resin. A method of joining a metal and a resin by exhibiting an anchor effect between the metal and the resin is disclosed.
Patent Document 2 discloses a method in which an adhesive is applied to the surface of a metal member, and the resin is brought into contact with the surface of the metal member via the adhesive to bond the metal to the resin.
Patent Document 3 discloses a method of imparting metal adhesiveness to a resin itself used for injection molding, bringing the resin into contact with the metal, and joining the metal to the resin.

International Publication No. 2009/078382 Japanese Unexamined Patent Publication No. 2015-047732 JP-A-2010-030177

In the invention described in Patent Document 1, since the metal and the resin are directly bonded, the composite part is inferior in stress relaxation property. In addition, since the surface treatment of the metal member itself has a short pot life, it is difficult to manage the process from the surface treatment of the metal member to the molding of the resin. Furthermore, the resins that meet the molding conditions have been limited.
In the invention described in Patent Document 2, since the adhesiveness between the metal and the resin is insufficient, the resin is easily peeled off from the metal after molding the composite part. In addition, it has been difficult to secure the adhesiveness between the metal and the resin in the operating temperature range of the resin.
In the invention described in Patent Document 3, the shape and molding conditions of the composite part may be limited.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an adhesive composition having excellent adhesiveness to metals and resins, stress relaxation property, and heat resistance.

The present invention has the following aspects.
[1] The acrylic containing an acrylic rubber having at least one functional group selected from the group consisting of a carboxyl group, a hydroxyl group and an epoxy group, a thermosetting component that reacts with the functional group, and a curing accelerator. The rubber contains a copolymer of at least one of an acrylic acid ester and a derivative thereof and at least one of acrylonitrile and a derivative thereof, and is subjected to an ATR (Attention Total Reflection) method using a Fourier transformed infrared spectrophotometer (FT-IR). The ratio of the measured peak area of absorbance at the wave number (1740 cm ^-1 ) due to the carbonyl group of the acrylic acid ester to the peak area of absorbance at the wave number (2240 cm ^-1 ) due to the nitrile group of the acrylonitrile (nitrile group / An adhesive composition having a carbonyl group) of 0.001 or more and 0.02 or less.
[2] The adhesive composition according to [1], wherein the thermosetting component contains at least one of an epoxy resin and a silane coupling agent.
[3] The adhesive composition according to [1] or [2], which further comprises a plasticizer.
[4] The adhesive composition according to any one of [1] to [3], which further contains a phenol resin.

According to the present invention, it is possible to provide an adhesive composition having excellent adhesiveness to metals and resins, stress relaxation property, and heat resistance.

Embodiments of the adhesive composition of the present invention will be described.
It should be noted that the present embodiment is specifically described in order to better understand the gist of the invention, and is not limited to the present invention unless otherwise specified.

[Adhesive composition]
The adhesive composition according to the present embodiment comprises an acrylic rubber having at least one functional group selected from the group consisting of a carboxyl group, a hydroxyl group and an epoxy group, a heat-curing component that reacts with the functional group, and curing acceleration. The acrylic rubber comprises a copolymer of at least one of an acrylic acid ester and a derivative thereof and at least one of acrylonitrile and a derivative thereof, and a Fourier transform infrared spectrophotometer (FT-IR) was used. The peak area of the absorbance at the wave number (1740 cm ^-1 ) due to the carbonyl group of the acrylic acid ester and the absorbance at the wave number (2240 cm ^-1 ) due to the nitrile group of the acrylonitrile measured by the ATR (Attenuated Total Reflection) method. The peak area ratio (nitrile group / carbonyl group) is 0.001 or more and 0.02 or less.

In the adhesive composition according to the present embodiment, it is caused by the carbonyl group (C = O) of the acrylic acid ester measured by the ATR (Nitriled Total Reflection) method using a Fourier transform infrared spectrophotometer (FT-IR). The ratio (nitrile group / carbonyl group) of the peak area of absorbance at wave number (1740 cm ^-1 ) to the peak area of absorbance at wave number (2240 cm ^-1 ) due to the nitrile group (C≡N) of acrylonitrile is 0.001. It is 0.02 or more, preferably 0.0015 or more and 0.015 or less, and more preferably 0.002 or more and 0.01 or less. Hereinafter, the ratio of the nitrile group to the carbonyl group may be referred to as "N / C ratio".

If the "N / C ratio" is less than 0.001, the adhesiveness of the adhesive composition at room temperature and high temperature deteriorates, so that the members cannot be joined to each other during metal resin integral molding, or even if they can be joined. When the metal-resin integrally molded product receives stress or load, problems such as easy peeling between the members are likely to occur. Further, since the cohesive force of the cured product of the adhesive composition at high temperature is weakened, when the metal resin integrally molded product receives stress or load during heat, the adhesive layer is broken or peeling occurs between the members. It will be easier. On the other hand, when the "N / C ratio" exceeds 0.02, the flexibility of the cured product of the adhesive composition at low temperature deteriorates, and when the metal resin integrally molded product receives impact or thermal stress at low temperature. , The stress generated between each member cannot be relaxed, and peeling between each member is likely to occur.

Acrylic rubber contains a copolymer of acrylic acid ester and acrylonitrile.
When the total amount of the copolymer is 100% by mass, the content of the structural unit derived from the acrylic acid ester in the copolymer is preferably 50% by mass or more, and more preferably 60% by mass or more.
If the content of the structural unit derived from the acrylic acid ester is less than 50% by mass, the flexibility of the cured product of the adhesive composition is also lowered, and the stress relaxation property is deteriorated.

When the total amount of the copolymer is 100% by mass, the content of the structural unit derived from acrylonitrile in the copolymer is preferably 50% by mass or less, and more preferably 40% by mass or less.
When the content of the structural unit derived from acrylonitrile exceeds 50% by mass, the solubility of the adhesive composition in the solvent becomes low, the viscosity of the paint becomes high when it is made into a paint, and the fluidity of the paint is lost ( Problems such as gelling) and difficulty in handling the adhesive paint occur. In addition, the flexibility of the cured product of the adhesive composition is also reduced, and the stress relaxation property is deteriorated.

The acrylic acid ester is not particularly limited as long as it can be copolymerized with acrylonitrile, and for example, methyl acrylate, ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, 2-dimethylaminoethyl acrylate, Examples thereof include 2-hydroshikiethyl acrylate and the like, and derivatives thereof.

A derivative of acrylonitrile may be used instead of acrylonitrile.

The at least one functional group selected from the group consisting of a carboxyl group, a hydroxyl group and an epoxy group contained in the acrylic rubber is at least one selected from the group consisting of a carboxyl group-containing monomer, a hydroxyl group-containing monomer and an epoxy group-containing monomer. , Is preferably due to the compound obtained by polymerizing the acrylic acid ester and the acrylonitrile.
The carboxyl group-containing monomer is not particularly limited, and examples thereof include (meth) acrylic acid, itaconic acid, maleic acid, fumaric acid, and crotonic acid. Further, the anhydrides of these carboxyl group-containing monomers can also be used as the carboxyl group-containing monomers.
Examples of the hydroxyl group-containing monomer include 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl acrylate, 2-hydroxypropyl methacrylate, 3-hydroxypropyl acrylate, 3-hydroxypropyl methacrylate, and the like. 4-Hydroxybutyl acrylate, 4-hydroxybutyl methacrylate, 2-hydroxy-3-chloropropyl acrylate, 2-hydroxy-3-chloropropyl methacrylate, 2-hydroxy-3-phenoxypropyl acrylate, 2 methacrylic acid -Hydroxy-3-phenoxypropyl and the like can be mentioned.
Examples of the epoxy group-containing monomer include glycidyl ether acrylate, glycidyl methacrylate ether, -2-ethyl glycidyl ether acrylate, and -2-glycidyl ether methacrylate.

The weight average molecular weight (Mw) of the copolymer is not particularly limited, but is preferably 1,000 or more and 3 million or less, and more preferably 10,000 or more and 1.5 million or less.
When the weight average molecular weight (Mw) of the copolymer exceeds 3 million, the paint loses its fluidity (gels) due to the remarkable thickening of the paint when it is made into a paint, and it becomes difficult to handle the adhesive paint. A problem occurs. On the other hand, when the weight average molecular weight (Mw) of the copolymer is less than 1000, the crosslink density of the cured product of the adhesive composition becomes high, and the flexibility of the cured product becomes poor. The Mw of the acrylic polymer is measured by gel permeation chromatography (GPC) in terms of standard polystyrene.

The glass transition point (Tg) of the copolymer is not particularly limited, but is preferably −60 ° C. or higher and 0 ° C. or lower, and more preferably −40 ° C. or higher and −20 ° C. or lower.
When the glass transition point (Tg) of the copolymer exceeds 0 ° C., the flexibility of the cured product of the adhesive composition at low temperature deteriorates, and the metal resin integrally molded product receives impact or thermal stress at low temperature. At that time, the stress generated between the members cannot be relaxed, and the peeling between the members is likely to occur. On the other hand, when the glass transition point (Tg) of the copolymer is less than -60 ° C., the cohesive force of the cured product of the adhesive composition at high temperature becomes weak, so that the metal-resin integrally molded product exerts stress or load when heated. When received, the adhesive layer is likely to break or peel off between the members.

The content of acrylic rubber in the adhesive composition is not particularly limited and can be appropriately selected depending on the production conditions. For example, it is preferably 20% by mass or more and 95% by mass or less, and 40% by mass or more. More preferably, it is 90% by mass or less.

The acrylic rubber may contain components other than the above-mentioned copolymer as long as it does not affect the properties of the copolymer.
Other components contained in acrylic rubber include, for example, amino group-containing monomers such as dimethylaminoethyl acrylate, dimethylaminoethyl methacrylate, diethylaminoethyl acrylate, diethylaminoethyl methacrylate, acrylamide, methacrylicamide, and N-methylolacrylamide. , N-Methylolmethacrylic amide and other amide group-containing monomers.

As a method for producing a copolymer of acrylic acid ester and acrylonitrile, a general copolymerization method is used, and for example, suspension polymerization, emulsion polymerization and the like are used.

The thermosetting component is not particularly limited as long as it reacts with the functional group of acrylic rubber, and examples thereof include an epoxy resin, a silane coupling agent, an isocyanate resin, and a diamine compound. Among these, epoxy resins and silane coupling agents are preferable because they easily react with acrylic rubber by heat and the cured product exhibits excellent heat resistance and adhesiveness.

Epoxy resins are compounds that have two or more epoxy groups in the molecule, such as diglycidyl ethers such as bisphenol A, bisphenol F, bisphenol S, resorcinol, dihydroquinaphthalene, and dicyclopentadiene diphenol. Examples thereof include alicyclic epoxy resins such as epoxidized phenol novolac, epoxidized cresol novolac, epoxidized cresol novolac, epoxidized trisphenylol methane, and epoxidized tetraphenylol ethane, or biphenyl type epoxy resin or novolak type epoxy resin. ..

The silane coupling agent is a compound having an organic functional group and a hydrolyzable silyl group in one molecule, and is, for example, N- (2-aminoethyl) -3-aminopropylmethyldimethoxysilane, N- (2-). Aminoethyl) -3-aminopropyltrimethoxysilane, N- (2-aminoethyl) -3-aminopropylmethyldiethoxysilane, N- (2-aminoethyl) -3-aminopropyltriethoxysilane, 3-amino Aminosilanes such as propyltrimethoxysilane and 3-aminopropyltriethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 3-glyceride Epoxysilanes such as sidoxylpropylmethyldiethoxysilane, mercaptosilanes such as 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, 3-methacryloxypropyltriethoxysilane, 3-methacryloxypropyltrimethoxy Examples thereof include vinyl silanes such as silane, vinyl trimethoxysilane, vinyl triethoxysilane, and vinyl tris (2-methoxyethoxy) silane. In particular, among these, epoxysilanes and aminosilanes are selected because they have good compatibility with acrylic rubber and easily react with acrylic rubber by heat, and the cured product exhibits excellent heat resistance and adhesiveness. preferable.

The isocyanate resin is a compound having an isocyanate group, for example, tolylene diisocyanate, chlorophenylenediisocyanate, hexamethylene diisocyanate, tetramethylene diisocyanate, isophorone diisocyanate, xylylene diisocyanate, diphenylmethane diisocyanate, hydrogenated. Isocyanate monomers such as diphenylmethane diisocyanate, adduct-based isocyanate compounds in which these isocyanate monomers are added to polyhydric alcohols such as trimethylpropane, isocyanurate compounds, bullet-type compounds, and known polyether polyols, polyester polyols, acrylic polyols, and polybutadienes. Examples thereof include urethane prepolymer type isocyanate obtained by addition-reacting a polyol, a polyisoprene polyol, or the like.

Examples of the diamine compound include 3,4'-diaminodiphenyl ether, 4,4'-diaminodiphenyl ether, 3,3'-dimethyl-4,4'-diaminodiphenyl ether, 3,3'-diaminodiphenyl ether, and 4,4'. -Diaminobenzophenone, 3,3'-dimethyl-4,4'-diaminobenzophenone, 3,3'-diaminodiphenylmethane, 3,3'-dimethoxy-4,4'-diaminodiphenylmethane, 2,2'-bis (3) -Aminophenyl) Propane, 4,4'-diaminodiphenylsulfone, 3,3′-diaminodiphenylsulfone, benzidine, 3,3′-dimethylbenzidine, 3,3′-dimethoxybenzidine, 3,3′-diaminobiphenyl, 1,3-bis (3-aminophenoxy) benzene, 2,2-bis [4- (4-aminophenoxy) phenyl] propane, 2,2-bis [3-methyl-4- (4-aminophenoxy) phenyl ] Propane, 2,2-bis [3-chloro-4- (4-aminophenoxy) phenyl] propane, 2,2-bis [3,5-dimethyl-4- (4-aminophenoxy) phenyl] propane, 1 , 1'-bis [4- (4-aminophenoxy) phenyl] ethane, 1,1'-bis [3-chloro-4- (4-aminophenoxy) phenyl] ethane, bis [4- (4-aminophenoxy) ) Benzene] methane, bis [3-methyl-4- (4-aminophenoxy) phenyl] methane, 4,4'-[1,4-phenylenebis (1-methylethylidene)] bisaniline, 4,4'-[ Examples thereof include 1,3-phenylenebis (1-methylethylidene)] bisaniline and 4,4'-[1,4-phenylenebis (1-methylethylidene)] bis (2,6-dimethylbisaniline).

Examples of the siloxane compound having amino groups at both ends include 1,3-bis (3-aminopropyl) -1,1,3,3-tetramethyldisiloxane and α, ω-bis (3-amino). (Propyl) polydimethylsiloxane (for example, tetramer to octameric of aminopropyl-terminated dimethylsiloxane), 1,3-bis (3-aminophenoxymethyl) -1,1,3,3-tetramethyldisiloxane , Α, ω-bis (3-aminophenoxymethyl) polydimethylsiloxane, 1,3-bis (2- (3-aminophenoxy) ethyl) -1,1,3,3-tetramethyldisiloxane, α, ω -Bis (2- (3-aminophenoxy) ethyl) polydimethylsiloxane, 1,3-bis (3- (3-aminophenoxy) propyl) -1,1,3,3-tetramethyldisiloxane, α, ω -Bis (3- (3-aminophenoxy) propyl) polydimethylsiloxane and the like can be mentioned.

Among the above siloxane compounds, in the case of polysiloxane, those having an average degree of polymerization of 2 to 33 (molecular weight of about 250 to 3000) are preferably used, and those having an average degree of polymerization of 4 to 24 (molecular weight of about about 250 to 3000) are preferably used. Those of 400 to 2000) are more preferably used.
Any one of the above epoxy resins, silane coupling agents and the like may be used alone, or two or more thereof may be mixed and used.

The content of the thermosetting component in the adhesive composition is not particularly limited and can be appropriately selected according to the production conditions. For example, 1 part by mass or more and 100 parts by mass with respect to 100 parts by mass of the acrylic rubber content. The amount is preferably 5 parts by mass or more, and more preferably 50 parts by mass or less.
If the content of the thermosetting component in the adhesive composition is less than 1 part by mass, the effect of containing the thermosetting component, that is, the cross-linking reaction between the acrylic rubber and the thermosetting component does not proceed, and the cured product of the adhesive composition However, it is difficult to develop excellent adhesiveness and heat resistance. When the content of the thermosetting component in the adhesive composition exceeds 100 parts by mass, the Tg of the cured product of the adhesive composition becomes high, and the flexibility and stress relaxation property at low temperatures tend to deteriorate.

The curing accelerator is not particularly limited as long as it can accelerate the reaction between the acrylic rubber and the thermosetting component, and examples thereof include an imidazole compound, a tertiary amine, an organic phosphorus compound, and a dicyandiamide.

Examples of the imidazole compound include 1,2-dimethylimidazole, 1-methyl-2-ethylimidazole, 2-methylimidazole, 2-ethyl-4-methylimidazole, 2-undecylimidazole, 2-heptadecylimidazole, 2 -Phenylimidazole, 1-benzyl-2-methylimidazole, 1-benzyl-2-phenylimidazole, 1-benzyl-2-phenylimidazole trimellitate, 1-benzyl-2-ethylimidazole, 1-benzyl-2 -Ethyl-5-methylimidazole, 2-ethylimidazole, 2-isopropylimidazole, 2-phenyl-4-benzylimidazole, 1-cyanoethyl-2-methylimidazole, 1-cyanoethyl-2-ethyl-4-methylimidazole, 1 -Cyanoethyl-2-undecylimidazole, 1-cyanoethyl-2-isopropylimidazole, 1-cyanoethyl-2-phenylimidazole, 1-cyanoethyl-2-methylimidazolium trimerite, 1-cyanoethyl-2-phenylimidazolium tri Meritate, 2,4-diamino-6- [2'-methylimidazolyl- (1')] -ethyl-s-triazine, 2,4-diamino-6- [2'-ethyl-4-methylimidazolyl- (1') 1')]-ethyl-s-triazine, 2,4-diamino-6- [2'-undecylimidazolyl- (1')]-ethyl-s-triazine, 2-methylimidazolium isocyanuric acid adduct, 2-Phenylimidazolium isocyanuric acid adduct, 2,4-diamino-6- [2'-methylimidazolyl- (1')]-ethyl-s-triazine-isocyanuric acid adduct, 2-phenyl-4, 5-Dihydroxymethylimidazole, 2-phenyl-4-benzyl-5-hydroxymethylimidazole, 4,4'-methylene-bis- (2-ethyl-5-methylimidazole), 1-aminoethyl-2-methylimidazole, 1-Cyanoethyl-2-phenyl-4,5-di (cyanoethoxymethyl) imidazole, 1-dodecyl-2-methyl-3-benzylimidazolium chloride, 2-methylimidazole / benzotriazole adduct, 1-aminoethyl- 2-Ethylimidazole, 1- (cyanoethylaminoethyl) -2-methylimidazole, N, N'-[2-methylimidazolyl- (1) -ethyl] -adipoildiamide, N, N'- Bis- (2-methylimidazolyl-1-ethyl) urea, N- (2-methylimidazolyl-1-ethyl) urea, N, N'-[2-methylimidazolyl- (1) -ethyl] dodecandioil diamide, Examples thereof include N, N'-[2-methylimidazolyl- (1) -ethyl] eikosandioil diamide, 1-benzyl-2-phenylimidazole, hydrochloride and the like.

Examples of the tertiary amine include 1,8-diaza-bicyclo [5.4.0] undecene-7, triethylenediamine, benzyldimethylamine, triethanolamine, dimethylaminoethanol, tris (dimethylaminomethyl) phenol and the like. Can be mentioned.

Examples of the organic phosphorus compound include tributylphosphine, methyldiphenylphosphine, triphenylphosphine, diphenylphosphine, phenylphosphine and the like.

Any one of these curing accelerators can be used alone, or two or more thereof can be mixed and used.
The cross-linking reaction (cross-linking density) between the acrylic rubber and the thermosetting component can be adjusted by appropriately selecting the curing accelerator.

The content of the curing accelerator in the adhesive composition is not particularly limited and can be appropriately selected according to the production conditions. However, for example, with respect to a total of 100 parts by mass of the content of the acrylic rubber and the thermosetting component. , 0.1 part by mass or more and preferably 10 parts by mass or less, and more preferably 0.5 parts by mass or more and 5 parts by mass or less.
If the content of the curing accelerator in the adhesive composition is less than 0.1 parts by mass, it is difficult to obtain the effect of containing the curing accelerator, that is, the effect of promoting the cross-linking reaction between the acrylic rubber and the thermosetting component, and the adhesive is adhered. The thermosetting time of the agent composition becomes long, resulting in poor productivity. In addition, it is difficult to obtain heat resistance of the cured adhesive. When the content of the curing accelerator in the adhesive composition exceeds 10 parts by mass, the cross-linking reaction between the acrylic rubber and the thermosetting component becomes remarkable, and the manufacturing conditions for integrally joining the metal and the resin can be adjusted. It gets harder. For example, the reaction of the adhesive proceeds remarkably due to the heat of the molding die between the time when the part in which the adhesive composition is attached to the metal is set in the molding die and the time when the molding resin is brought into contact with the molding die. When the molding resin is brought into contact with the molding resin, the adhesive cannot exhibit the adhesiveness, and the molding resin cannot be bonded.

The adhesive composition according to this embodiment preferably further contains a plasticizer.
The plasticizer is not particularly limited, and examples thereof include acrylic acid ester type, phthalate type, adipate type, phosphoric acid ester type, trimellitic acid ester type, citric acid ester type, epoxy type and polyester type. Can be mentioned. Any one of these plasticizers can be used alone, and two or more of these plasticizers can be mixed and used. Further, as the above-mentioned plasticizer, one containing a functional group such as a hydroxyl group, a carboxyl group, an epoxy group and an alkoxysilyl group may be used. Among these, acrylic acid ester type is preferable from the viewpoint of compatibility with acrylic rubber. When the adhesive composition contains a plasticizer, the glass transition point (Tg) of the adhesive composition can be lowered. By lowering the glass transition point (Tg) of the adhesive composition, the flexibility of the adhesive composition at low temperature is improved, and an adhesive composition having excellent stress relaxation property, particularly stress relaxation property at low temperature, is obtained. be able to.

The content of the plasticizer in the adhesive composition is not particularly limited and can be appropriately selected according to the production conditions. For example, 1 part by mass or more and 100 parts by mass with respect to 100 parts by mass of the acrylic rubber content. It is preferably 10 parts by mass or more and 100 parts by mass or less. If the content of the plasticizer in the adhesive composition is less than 1 part by mass, it is difficult to obtain the effect of containing the plasticizer, that is, the effect of lowering the glass transition point of the adhesive composition. When the content of the plasticizer in the adhesive composition exceeds 100 parts by mass, the plasticizer easily bleeds out to the surface of the adhesive composition from the cured adhesive composition or the cured product of the adhesive composition at the time of curing. As a result, there are problems such as poor adhesion to the adherend during molding and peeling from the interface of the adherend over time after the metal and the resin are integrally bonded.

The adhesive composition according to the present embodiment preferably further contains a phenol resin.
Examples of the phenol resin include alkyl-substituted phenols such as phenol, cresol and pt-butylphenol as raw material phenols, cyclic alkyl-modified phenols such as terpene, rosin, xylene and dicyclopentadiene, nitro groups, halogen groups and aminos. Examples thereof include those having a functional group containing a hetero atom such as a group and a cyano group, and those using a skeleton such as naphthalene and anthracene. Any one of these phenolic resins may be used alone, or two or more thereof may be mixed and used. Further, the above-mentioned phenol resin may be used instead of the above-mentioned thermosetting component. Since the adhesive composition contains a phenol resin, the cured product of the adhesive composition exhibits excellent heat resistance and excellent adhesiveness at high temperatures.

The content of the phenol resin in the adhesive composition is not particularly limited and can be appropriately selected according to the production conditions. For example, 1 part by mass or more and 100 parts by mass with respect to 100 parts by mass of the acrylic rubber content. It is preferably 5 parts by mass or more and 50 parts by mass or less. When the content of the phenol resin in the adhesive composition is less than 1 part by mass, the effect of containing the phenol resin in the cured product of the adhesive composition, that is, the excellent heat resistance of the cured product and the excellent heat resistance at high temperature It is difficult to obtain adhesiveness. When the content of the phenol resin in the adhesive composition exceeds 50 parts by mass, the Tg after curing becomes high, and the flexibility and stress relaxation property of the cured product of the adhesive composition at low temperature tend to deteriorate.

The adhesive composition according to the present embodiment may contain components other than the plasticizer and the phenol resin as long as it does not affect the characteristics of the adhesive composition.
Other components contained in the adhesive composition include, for example, mold release agents such as acid amides, esters and paraffins, tackifiers, stress relieving agents such as nitrile rubber and butadiene rubber, chlorinated paraffin and brom. Flame retardants such as benzene and antimony trioxide, titanate coupling agents, fused silica, glass flakes, glass beads, glass balloons, talc, alumina, calcium silicate, aluminum hydroxide, calcium carbonate, barium sulfate, magnesia, silicon nitride , Boron nitride, ferrite, rare earth cobalt, gold, silver, nickel, copper, lead, iron powder, metal powder such as iron oxide, sand iron, inorganic filler such as graphite, carbon, petal handle, yellow lead or conductive particles Etc., colorants such as dyes and pigments, carbon fibers, glass fibers, boron fibers, silicon carbide fibers, alumina fibers, silica-alumina fibers and other inorganic fibers, polyamide fibers, polyester fibers, cellulose fibers, carbon fibers and other organic fibers. Fibers, antioxidants, light stabilizers, moisture resistance improvers, thixotropy-imparting agents, diluents, defoaming agents, antistatic agents, lubricants, ultraviolet absorbers and the like can be blended.

The adhesive composition according to the present embodiment preferably has a glass transition point (Tg) of −60 ° C. or higher and 0 ° C. or lower, and more preferably −40 ° C. or higher and −20 ° C. or lower.
When the glass transition point (Tg) of the adhesive composition exceeds 0 ° C., the flexibility of the cured product of the adhesive composition at low temperature deteriorates, and the metal resin integrally molded product receives impact or cold stress at low temperature. At that time, the stress generated between the members cannot be relaxed, and the peeling between the members is likely to occur. On the other hand, when the glass transition point (Tg) of the adhesive composition is less than -60 ° C, the cohesive force of the cured product of the adhesive composition at high temperature becomes weak, so that the metal-resin integrally molded product is stressed or loaded during heat. When this is received, the adhesive layer is likely to be broken or peeling is likely to occur between the members.

The method for producing the adhesive composition according to the present embodiment is not particularly limited, and for example, one in which each component is kneaded with a roll mill or the like and dissolved in a liquid medium, or one in which each component is previously dissolved in a liquid medium is used. It can be produced by preparing a mixed or dispersed material (hereinafter, also referred to as "adhesive layer paint"), applying this to an adherend, drying and removing the solvent to form an adhesive layer.

Examples of the method for applying the adhesive layer paint include a coating method, a printing method, and a dispensing method, and any method may be used as long as the dimensional accuracy and the coating shape can be controlled.
Examples of coating methods include air doctor coating, bar coating, blade coating, knife coating, reverse coating, transfer coating, gravure roll coating, kiss coating, cast coating, spray coating, slot orifice coating, calendar coating, and dam coating. , Dip coating, die coating and other coating methods.

In the case of the coating method, the support base material wound up in a roll state is unwound, and the adhesive layer paint is continuously applied to the support base material using a known coating machine or the like, and the adhesive layer paint is applied. The supporting base material is passed through a drying furnace and dried at 50 ° C. to 200 ° C. for 1 minute to 10 minutes, and if necessary, a protective film is attached using a roll laminator when the substrate is removed from the drying furnace. A method is used in which the formed adhesive tape is wound into a roll.

Examples of the printing method include intaglio printing such as gravure printing and stencil printing such as screen printing.
The drying temperature at which the applied adhesive layer paint is dried is not particularly limited, but is preferably in the range of room temperature to 150 ° C. The drying time is not particularly limited, but is preferably in the range of 1 minute to 24 hours, for example. The drying temperature and drying time are appropriately selected according to the productivity.

The viscosity of the adhesive coating material in this embodiment is preferably liquid at room temperature, and is particularly preferably in the range of 0.001 Pa · s to 1000 Pa · s at 25 ° C. However, it can be used in the present embodiment as long as it is solid at room temperature but becomes liquid when heated.
The thickness of the adhesive layer can be adjusted by adjusting the solid content concentration of the adhesive layer paint and the coating thickness.

In the adhesive composition of the present embodiment described above, an acrylic rubber having at least one functional group selected from the group consisting of a carboxyl group, a hydroxyl group and an epoxy group, a heat-curing component that reacts with the functional group, and the like. The acrylic rubber contains a curing accelerator and at least one copolymer of an acrylic acid ester and a derivative thereof and at least one of acrylonitrile and a derivative thereof, and a Fourier transform infrared spectrophotometer (FT-IR) is used. , The peak area of the absorbance at the wave number (1740 cm ^-1 ) due to the carbonyl group of the acrylic acid ester measured by the ATR (Attention Total Reflection) method, and the absorbance at the wave number (2240 cm ^-1 ) due to the nitrile group of the acrylonitrile. The peak area ratio (nitrile group / carbonyl group) of is 0.001 or more and 0.02 or less. Therefore, the adhesive composition of the present embodiment is excellent in adhesiveness to metals and resins, as well as stress relaxation and heat resistance. Therefore, the adhesive composition of the present embodiment can be suitably used for integral molding of metal and resin in insert molding and hot press molding.

Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples, but the present invention is not limited to the following Examples.

[Example 1]
A rubber-like copolymer of a monomer having at least one functional group selected from the group consisting of a carboxyl group, a hydroxyl group and an epoxy group, and an acrylic acid ester and an acrylonitrile (weight average molecular weight (Mw): 900,000, glass transition Point (Tg): -15 ° C, N / C ratio: 0.0070) 100 parts by mass, epoxy resin (trade name: JER828, manufactured by Mitsubishi Chemical Co., Ltd.) 25 parts by mass, and curing accelerator (2-ethyl) 1-4 parts by mass of -4-methylimidazole) was mixed using a roll mill (manufactured by Inoue Seisakusho Co., Ltd.) to obtain the adhesive composition of Example 1.

[Example 2]
Example 2 in the same manner as in Example 1 except that 50 parts by mass of an acrylic acid ester-based plasticizer (trade name: ARUFON UP1000, manufactured by Toagosei Co., Ltd.) was added to the adhesive composition of Example 1. An adhesive composition was obtained.

[Example 3]
A rubber-like copolymer of a monomer having at least one functional group selected from the group consisting of a carboxyl group, a hydroxyl group and an epoxy group, and an acrylic acid ester and an acrylonitrile (weight average molecular weight (Mw): 900,000, glass transition Instead of the point (Tg): -15 ° C., N / C ratio: 0.0070), a monomer having at least one functional group selected from the group consisting of a carboxyl group, a hydroxyl group and an epoxy group, and an acrylic acid ester. Example 1 except that a rubber-like copolymer of and acrylonitrile (weight average molecular weight (Mw): 900,000, glass transition point (Tg): -15 ° C., N / C ratio: 0.002) was used. In the same manner, the adhesive composition of Example 3 was obtained.

[Example 4]
In the same manner as in Example 3 except that 50 parts by mass of an acrylic acid ester-based plasticizer (trade name: ARUFON UP1000, manufactured by Toagosei Co., Ltd.) was added to the adhesive composition of Example 3. An adhesive composition was obtained.

[Example 5]
A rubber-like copolymer of a monomer having at least one functional group selected from the group consisting of a carboxyl group, a hydroxyl group and an epoxy group, and an acrylic acid ester and an acrylonitrile (weight average molecular weight (Mw): 900,000, glass transition Instead of the point (Tg): -15 ° C., N / C ratio: 0.0070), a monomer having at least one functional group selected from the group consisting of a carboxyl group, a hydroxyl group and an epoxy group, and an acrylic acid ester. And Example 1 except that a rubber-like copolymer with acrylonitrile (weight average molecular weight (Mw): 900,000, glass transition point (Tg): -30 ° C., N / C ratio: 0.0040) was used. Similarly, the adhesive composition of Example 5 was obtained.

[Example 6]
Epoxy resin (trade name: JER828, manufactured by Mitsubishi Chemical Corporation) was added in an amount of 5 parts by mass, curing accelerator (2-ethyl-4-methylimidazole) was added in an amount of 0.2 parts by mass, and phenol resin (product). Name: TD-773, DIC Corporation) The adhesive composition of Example 6 was obtained in the same manner as in Example 5 except that the amount was 20 parts by mass.

[Example 7]
Example 6 in the same manner as in Example 6 except that the epoxy resin of Example 6 (trade name: JER828, manufactured by Mitsubishi Chemical Corporation) was used as a silane coupling agent (3-glycidoxypropyltrimethoxysilane). The adhesive composition of 7 was obtained.

[Example 8]
A rubber-like copolymer of a monomer having at least one functional group selected from the group consisting of a carboxyl group, a hydroxyl group and an epoxy group, and an acrylic acid ester and an acrylonitrile (weight average molecular weight (Mw): 900,000, glass transition Instead of the point (Tg): -15 ° C., N / C ratio: 0.0070), a monomer having at least one functional group selected from the group consisting of a carboxyl group, a hydroxyl group and an epoxy group, and an acrylic acid ester. Same as Example 1 except that a rubber-like copolymer of epoxide and acrylonitrile (weight average molecular weight (Mw): 900,000, glass transition point (Tg): 0 ° C., N / C ratio: 0.017) was used. The adhesive composition of Example 8 was obtained.

[Comparative Example 1]
A rubber-like copolymer of a monomer having at least one functional group selected from the group consisting of a carboxyl group, a hydroxyl group and an epoxy group, and an acrylic acid ester and an acrylonitrile (weight average molecular weight (Mw): 900,000, glass transition Instead of the point (Tg): -15 ° C., N / C ratio: 0.0070), an acrylic acid ester and acrylonitrile having at least one functional group selected from the group consisting of a carboxyl group, a hydroxyl group and an epoxy group. In the same manner as in Example 1 except that the rubber-like copolymer (weight average molecular weight (Mw): 900,000, glass transition point (Tg): 10 ° C., N / C ratio: 0.030) was used. The adhesive composition of Comparative Example 1 was obtained.

[Comparative Example 2]
A rubber-like copolymer of a monomer having at least one functional group selected from the group consisting of a carboxyl group, a hydroxyl group and an epoxy group, and an acrylic acid ester and an acrylonitrile (weight average molecular weight (Mw): 900,000, glass transition Instead of a point (Tg): -15 ° C., N / C ratio: 0.0070), a monomer and acrylic acid ester having at least one functional group selected from the group consisting of a carboxyl group, a hydroxyl group and an epoxy group. (Weight average molecular weight (Mw): 900,000, glass transition point (Tg): -30 ° C., N / C ratio: 0), except that the rubber-like copolymer of the above was used. The adhesive composition of Example 2 was obtained.

[Comparative Example 3]
A rubber-like copolymer of a monomer having at least one functional group selected from the group consisting of a carboxyl group, a hydroxyl group and an epoxy group, and an acrylic acid ester and an acrylonitrile (weight average molecular weight (Mw): 900,000, glass transition Instead of a point (Tg): -15 ° C., N / C ratio: 0.0070), a monomer and acrylic acid ester having at least one functional group selected from the group consisting of a carboxyl group, a hydroxyl group and an epoxy group. The same as in Example 1 except that a rubbery copolymer with ethylene (weight average molecular weight (Mw): 900,000, glass transition point (Tg): -30 ° C., N / C ratio: 0) was used. , An adhesive composition of Comparative Example 3 was obtained.

[Evaluation]
"Measurement of N / C ratio"
A Fourier transform infrared spectrophotometer (FT-IR, trade name: Spectrum100, manufactured by Perkin Elmer Japan Co., Ltd.) for the copolymers and adhesive compositions of Examples 1 to 8 and Comparative Examples 1 to 3. The N / C ratio was measured by the ATR (Attenuated Total Reflection) method.
Regarding the adhesive composition, the adhesive composition before curing without heating and the adhesive after curing heated under the same conditions as "(5) Evaluation of stress relaxation property (glass transition point (Tg))" below. The N / C ratio in the composition (adhesive layer) was measured, and the results are shown in Tables 1 and 2.

The calculation method of the N / C ratio is shown below.
The infrared absorption spectrum of the adhesive composition before and after curing or only the copolymer is measured. After ATR correction and absorbance conversion, the peak areas (S1, S2) at the following two wave numbers are calculated.
S1 is an integral value of the peak of the nitrile group (C≡N portion, wave number 2240 cm ^-1 ) of acrylic rubber. S2 is an integral value of the peak of the carbonyl group (C = O portion, wave number 1740 cm ^-1 ) of the acrylic rubber. The integral value of the carbonyl group peak was used as a reference, assuming that it did not change before and after curing.
The ratio of S1 / S2 was calculated as the N / C ratio before and after curing of the adhesive composition or only the copolymer.
The larger the N / C ratio, the higher the acrylonitrile ratio before and after curing of the adhesive composition or in the copolymer. On the other hand, the smaller the N / C ratio, the smaller the acrylonitrile ratio before and after curing of the adhesive composition or in the copolymer.

"Evaluation of adhesiveness"
(1) Preparation of Thermosetting Adhesive Sheet with PET Film 100 parts by mass of the adhesive composition of Examples 1 to 8 and Comparative Examples 1 to 3 is dissolved in 400 parts by weight of methyl ethyl ketone to prepare an adhesive coating material. Was prepared.
An adhesive paint was applied on the release-treated surface of the release PET film having a thickness of 38 μm so that the thickness after drying was 100 μm.
The release PET film coated with the adhesive paint is dried and dessolved in a hot air circulation type oven set at 80 ° C. to form a coating film (adhesive layer) composed of the adhesive paint, and the coating is immediately applied. Another release PET was attached to the surface of the film (adhesive layer) opposite to the surface in contact with the release PET film to prepare a heat-curable adhesive sheet with a PET film.

(2) Preparation of PBT / Aluminum Bonded Sample The thermosetting adhesive sheet with PET film was cut into 5 mm × 5 mm.
One of the release PET films of the thermosetting adhesive sheet with PET film was peeled off, and the adhesive layer side was attached to the metal plate. As the metal plate, an aluminum A5052 material (20 mm × 30 mm, thickness 1.5 mm) was used.
The other release PET film of the thermosetting adhesive sheet with PET film was peeled off to obtain a metal / adhesive sheet attached product.
The above-mentioned metal / adhesive sheet pasted product was heat-treated at 120 ° C. for 30 minutes using a heat circulation type oven to heat-cure the adhesive layer (at this time, the adhesive layer was not completely cured).
A metal / adhesive sheet affixed product obtained by thermosetting the adhesive layer is placed on a hot plate heated to 260 ° C., and a resin material made of polyphenylene terephide (PBT) is further placed on the adhesive layer. A PBT-aluminum bonded sample was prepared by pressurizing from the PBT resin material side at 50 kPa for 20 seconds. As the PBT resin material, a plate material manufactured by Toyama Light Rough Material Co., Ltd. (10 mm × 10 mm, thickness 10 mm) was used.
It should be noted that the adhesive layer itself is also appropriately wetted with the aluminum and the PBT resin material due to the heat during the above processing, and the cross-linking further proceeds, so that the adhesive layer is firmly bonded to the aluminum and the PBT.

(3) Evaluation of Adhesiveness at Room Temperature The strength (shear strength) of the above PBT-aluminum bonded sample when pressed against a PBT resin material in the shear direction was measured in an environment of 25 ° C.
A shear force tester SL5000 manufactured by Imada Seisakusho Co., Ltd. was used to measure the shear strength. The measurement speed was 50 mm / min.
Those with a shear strength of less than 100 kPa, those with a PBT resin material and an aluminum material that could not be joined were marked with "x", those with a shear strength of 100 kPa to 200 kPa were marked with "Δ", and those with a shear strength of 100 kPa were marked with "○". .. The results are shown in Tables 1 and 2.

(4) Evaluation of Adhesiveness (High Temperature Characteristics) at Heat The strength (shear strength) of the above PBT / aluminum bonded sample when pressed against a PBT resin material in the shear direction was measured in an environment of 130 ° C. ..
A shear force tester SL5000 manufactured by Imada Seisakusho Co., Ltd. was used to measure the shear strength. The measurement speed was 50 mm / min.
Those with a shear strength of less than 100 kPa, those with a PBT resin material and an aluminum material that could not be joined were marked with "x", those with a shear strength of 100 kPa to 200 kPa were marked with "Δ", and those with a shear strength of 100 kPa were marked with "○". .. The results are shown in Tables 1 and 2.

(5) Evaluation of stress relaxation property (glass transition point (Tg)) In order to evaluate stress relaxation property, the glass transition point (Tg) of the adhesive layer after thermosetting the adhesive layer is measured by differential scanning calorimetry. (DSC: differential scanning calorimetry).
The adhesive layer of the thermosetting adhesive sheet with PET film is taken out, placed on an aluminum foil petri dish, heat-treated at 120 ° C. for 30 minutes using a heat circulation oven, and then heated to 260 ° C. using a hot plate. Heat-treated for 20 seconds.
The DSC measurement was carried out in a nitrogen atmosphere in the range of −80 ° C. to + 300 ° C. under the condition of a temperature rise rate of 10 ° C./min, and the glass transition point (Tg) was determined from the inflection point of the heat flow curve.
A glass transition point of less than -20 ° C was designated as "◯", a glass transition point of -20 ° C to 0 ° C was designated as "Δ", and a glass transition point of more than 0 ° C was designated as "x". The results are shown in Tables 1 and 2.

From the results of Tables 1 and 2, the adhesive compositions of Examples 1 to 8 are superior to the adhesive compositions of Comparative Examples 1 to 3 in adhesiveness, high temperature characteristics and stress relaxation. It was confirmed that.

According to the adhesive composition of the present invention, it can be suitably used for integral molding of metal and resin in insert molding and hot press molding.

Claims (4)

Acrylic rubber having at least one functional group selected from the group consisting of a carboxyl group, a hydroxyl group and an epoxy group, a thermosetting component that reacts with the functional group, and a curing accelerator are contained.
The acrylic rubber contains at least one copolymer of acrylic acid ester and its derivative and at least one of acrylonitrile and its derivative.
The peak area of absorbance at the wave number (1740 cm ^-1 ) due to the carbonyl group of the acrylic acid ester measured by the ATR (Attenuated Total Reflection) method using a Fourier transform infrared spectrophotometer (FT-IR), and the acrylonitrile. An adhesive composition having a peak area ratio (nitrile group / carbonyl group) of absorbance at a wave number (2240 cm ^-1 ) due to the nitrile group of 0.001 or more and 0.02 or less. The adhesive composition according to claim 1, wherein the thermosetting component contains at least one of an epoxy resin and a silane coupling agent. The adhesive composition according to claim 1 or 2, further comprising a plasticizer. The adhesive composition according to any one of claims 1 to 3, further comprising a phenol resin.