JP4707320B2 - Two-component acrylic adhesive composition and joined body using the same - Google Patents

Description

The present invention relates to a two-part acrylic adhesive composition having a thixotropic viscosity with good coatability.

From the viewpoint of labor saving, resource saving, and energy saving, a room-temperature fast-curing adhesive composition is used as an adhesive that bonds at room temperature in a short time. Conventionally, room-temperature fast-curing adhesive compositions include two-part fast-curing epoxy adhesive compositions, anaerobic adhesive compositions, instantaneous adhesive compositions, and second-generation acrylic adhesive compositions (SGA). )It has been known.

The two-part type fast-curing epoxy adhesive is one in which a main agent and a curing agent are measured, mixed, applied to an adherend, and cured by a reaction between the main agent and the curing agent. However, the two-part type fast-curing epoxy adhesive is required to have higher peel strength and impact strength.

The anaerobic adhesive is cured by pressure-bonding the adhesive composition between adherends to block air. However, the anaerobic adhesive composition is required to have a property of curing even if the part of the adhesive composition comes out of the adherend when it is pressure-bonded, even if the part of the adhesive composition comes into contact with air. . In addition, a property of curing even when the clearance between adherends is large is required.

Instant adhesives usually have cyanoacrylate as the main component and are excellent in workability. However, higher peel strength and impact strength are required.

SGA is a two-part acrylic adhesive, but it does not require accurate metering of the two agents, and even if metering or mixing is incomplete, it can be cured at room temperature for several minutes to several tens of minutes just by contacting the two agents. In addition, it has excellent workability, high peel strength, high impact strength, and good curing of the exposed portion, so it is widely used from the electrical / electronic parts field to the civil engineering / architecture field.

In general, as a method for applying SGA, there are a method of applying with a dispenser having a mixing nozzle attached to the tip, and a method of spreading two liquids in a specific container and spreading them on the adherend surface by brushing or the like.

An index of the workability of the coating work is the thixotropic property of the adhesive. However, if the thixotropic property of the SGA is low, the thread breakage of the adhesive is poor when the adhesive is discharged from the coating machine on an assembly line or the like. When moving the line, there is a possibility that the part other than the bonded part will be stained with the adhesive dripping from the coating machine. Further, when the adhesive is applied to a vertical surface, the applied adhesive may hang down due to its own weight, and the thickness of the adhesive may be biased.

As a method for imparting thixotropic properties to SGA, Patent Document 1 discloses a method of adding a graft (core-shell) polymer such as ABS, MBS, or MBAS. It is not disclosed whether a polymer is preferred.
JP-A-53-2543.

In view of the state of the prior art, the present invention provides a two-part acrylic adhesive having excellent thixotropic properties that has good thread breakage and does not easily sag even when applied to a vertical surface. With the goal.

As a result of various investigations for the purpose of solving the problems of the prior art, the present invention has an acrylic adhesive composition comprising a (meth) acrylic acid derivative monomer, a polymerization initiator, a reducing agent, and a diene core-shell polymer. In the case of selecting a diene-based core-shell polymer having specific properties, the two-part acrylic system having excellent thixotropic properties, which has good thread breakage and does not hang easily even when applied to a vertical surface The knowledge that an adhesive can be obtained has been obtained, and the present invention has been achieved.

That is, the present invention is an acrylic adhesive composition comprising (1) a (meth) acrylic acid derivative monomer, (2) a polymerization initiator, (3) a reducing agent, and (4) a diene core-shell polymer. The diene-based core-shell polymer is an MBS resin, is swellable in the (meth) acrylic acid derivative monomer, and has a swelling degree of 9.5 or more in toluene at 25 ° C. (5) A two-part acrylic adhesive composition comprising an elastomer soluble in a (meth) acrylic acid derivative monomer, ) A two-component acrylic adhesive composition in which the core portion of the diene-based core-shell polymer is mainly composed of polybutadiene and the shell portion is composed mainly of a copolymer of styrene and a (meth) acrylic acid derivative. Further, (5) a two-component acrylic adhesive composition in which the elastomer soluble in the (meth) acrylic acid derivative monomer is a diene copolymer, and further bonded by these adhesives Is the body.

The adhesive composition of the present invention is a two-part acrylic adhesive composition having a thixotropic viscosity with good applicability, good thread breakage during application, and easy to apply on a vertical surface. Since it has the feature of excellent workability that does not sag, it can be applied to various industrial fields and is beneficial.

Hereinafter, the present invention will be described in detail. The (1) (meth) acrylic acid derivative monomer used in the present invention may be any as long as radical polymerization is possible. Here, examples of the (meth) acrylic acid derivative monomer include the following.

(I) General formula Z—O—R ₁
A monomer represented by
Wherein Z represents a (meth) acryloyl group, CH ₂ ═CHCOOCH ₂ —CH (OH) CH ₂ — group or CH ₂ ═C (CH ₃ ) COOCH ₂ —CH (OH) CH ₂ — group, R ₁ represents hydrogen, an alkyl group having 1 to 20 carbon atoms, a cycloalkyl group, a benzyl group, a phenyl group, a tetrahydrofurfuryl group, a glycidyl group, a dicyclopentyl group, a dicyclopentenyl group, a (meth) acryloyl group, and an isobornyl group. )

Examples of such a monomer include methyl (meth) acrylate, cyclohexyl (meth) acrylate, benzyl (meth) acrylate, tetrahydrofurfuryl (meth) acrylate, dicyclopentyl (meth) acrylate, (meth ) Dicyclopentenyl acrylate, glycerol (meth) acrylate, glycerol di (meth) acrylate, isobornyl (meth) acrylate, and (meth) acrylic acid.

(Ii) General formula Z—O— (R ₂ O) _p —R ₁
A monomer represented by
(In the formula, Z and R ₁ are as described above. R ₂ represents —C ₂ H ₄ —, —C ₃ H ₆ —, —CH ₂ CH (CH ₃ ) —, —C ₄ H ₈ — or — C ₆ H ₁₂ -is shown, and p represents an integer of 1 to 25)

Examples of such monomers include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, ethoxyethyl (meth) acrylate, polyethylene glycol (meth) acrylate, phenoxyethyl (meth) acrylate, di Examples include cyclopentenyloxyethyl (meth) acrylate, phenoxydiethylene glycol (meth) acrylate, tripropylene glycol di (meth) acrylate, and 1,6-hexanediol di (meth) acrylate.

で示される単量体。
（式中、Ｚ及びＲ₂は前述の通りである。Ｒ₃は水素又は炭素数１〜４のアルキル基を示し、ｑは０〜８の整数を表す） (Iii) General formula

A monomer represented by
(In the formula, Z and R ₂ are as described above. R ₃ represents hydrogen or an alkyl group having 1 to 4 carbon atoms, and q represents an integer of 0 to 8)

Examples of such monomers include 2,2-bis (4- (meth) acryloxyphenyl) propane, 2,2-bis (4- (meth) acryloxyethoxyphenyl) propane, and 2,2-bis. (4- (meth) acryloxydiethoxyphenyl) propane, 2,2-bis (4- (meth) acryloxypropoxyphenyl) propane and 2,2-bis (4- (meth) acryloxytetraethoxyphenyl) propane Etc.

(Iv) A (meth) acrylic acid ester of a polyhydric alcohol not included in the monomer described in (i), (ii) or (iii) above.

Examples of such a monomer include trimethylolpropane tri (meth) acrylate, neopentyl glycol di (meth) acrylate, pentaerythritol tetra (meth) acrylate, dipentaerythritol hexa (meth) acrylate, and the like.

(V) A urethane prepolymer having a (meth) acryloyloxy group. Such a monomer can be obtained, for example, by reacting a (meth) acrylic acid ester having a hydroxyl group, an organic polyisocyanate, and a polyhydric alcohol.

Examples of the (meth) acrylic acid ester having a hydroxyl group include hydroxyethyl (meth) acrylate, hydroxypropyl (meth) acrylate, and hydroxybutyl (meth) acrylate.

Examples of the organic polyisocyanate include toluene diisocyanate, 4,4-diphenylmethane diisocyanate, hexamethylene diisocyanate, and isophorone diisocyanate.

Examples of the polyhydric alcohol include polyethylene glycol, polypropylene glycol, polytetramethylene glycol, and polyester polyol.

（式中、Ｒは CH₂＝CR₄CO(OR₅)_m−基（但し、Ｒ₄は水素又はメチル基、Ｒ₅は−C₂H₄−、−C₃H₆−、−CH₂CH(CH₃)−、−C₄H₈−、−C₆H₁₂−又は

を示し、ｍは１〜１０の整数を表す。）を示し、ｎは１又は２の整数を表す） (Vi) An acidic phosphoric acid compound represented by the general formula (I).

(In the formula, R is CH ₂ ═CR ₄ CO (OR ₅ ) _m — group (where R ₄ is hydrogen or methyl group, R ₅ is —C ₂ H ₄ —, —C ₃ H ₆ —, —CH ₂ CH (CH ₃ )-, -C ₄ H _8- , -C ₆ H ₁₂ -or

M represents an integer of 1 to 10. ) And n represents an integer of 1 or 2)

Examples of the acidic phosphoric acid compound represented by the general formula (I) include acid phosphooxyethyl (meth) acrylate, acid phosphooxypropyl (meth) acrylate and bis (2- (meth) acryloyloxyethyl) phosphate. Can be mentioned.

As mentioned above, the monomer of (i)-(vi) can use 1 type (s) or 2 or more types. Among these, one or two or more members of the group consisting of (i), (ii) and (vi) are preferable in that adhesion is large and adhesion distortion of the adherend after bonding is small. ), (Ii) and (vi) are more preferably used in combination. When (i) and (ii) are used in combination, the composition ratio is preferably (i) :( ii) = 50 to 95: 5 to 50, more preferably 60 to 80:20 to 40, in terms of mass ratio. The amount of (vi) used is preferably 0.05 to 10 parts by mass and more preferably 0.1 to 5 parts by mass with respect to 100 parts by mass in total of (i) and (ii).

The (2) polymerization initiator used in the present invention is preferably an organic peroxide. Examples of organic peroxides include cumene hydroperoxide, paramentane hydroperoxide, tertiary butyl hydroperoxide, diisopropylbenzene dihydroperoxide, methyl ethyl ketone peroxide, benzoyl peroxide, and tertiary butyl peroxybenzoate. It is done. Among these, cumene hydroperoxide is preferable from the viewpoint of stability.

0.1-20 mass parts is preferable with respect to 100 mass parts of (meth) acrylic acid derivative monomers, and, as for the usage-amount of a polymerization initiator, 1-10 mass parts is more preferable. If it is less than 0.1 parts by mass, the curing rate may be delayed, and if it exceeds 20 parts by mass, the storage stability may be reduced.

The (3) reducing agent used in the present invention can be any known reducing agent that reacts with the polymerization initiator to generate radicals. Representative reducing agents include, for example, tertiary amines, thiourea derivatives and transition metal salts.

Examples of the tertiary amine include triethylamine, tripropylamine, tributylamine, and N, N-dimethylparatoluidine. Examples of the thiourea derivative include 2-mercaptobenzimidazole, methylthiourea, dibutylthiourea, tetramethylthiourea, and ethylenethiourea. Examples of the transition metal salt include cobalt naphthenate, copper naphthenate, and vanadyl acetylacetonate. Among these, thiourea derivatives are preferable from the viewpoint of reactivity, and ethylenethiourea is more preferable.

0.05-15 mass parts is preferable with respect to 100 mass parts of (meth) acrylic acid derivative monomers, and, as for the usage-amount of a reducing agent, 0.5-5 mass parts is more preferable. If it is less than 0.05 parts by mass, the curing rate may be slow, and if it exceeds 15 parts by mass, the storage stability may be reduced.

The composition of the core of the diene-based core-shell polymer swellable in the (4) (meth) acrylic acid monomer derivative blended in the present invention includes dienes such as polyisoprene, 1,4-polybutadiene, and 1,2-vinylpolybutadiene. Examples thereof include homomonomers and copolymers of system monomers. Examples of the composition of the shell include a copolymer of (meth) acrylic acid derivative and styrene, or a copolymer of (meth) acrylic acid derivative, styrene and acrylonitrile. Specific examples of these core-shell polymers include MBS resin and MBAS resin.

The swelling degree of these diene-based core-shell polymers in toluene at 25 ° C. is preferably 9.5 times or more, and more preferably 10.0 times or more. If the ratio is less than 9.5 times, the thixotropic property of the obtained adhesive is insufficient, and a preferable coating property may not be obtained.

5-40 mass parts is preferable with respect to 100 mass parts of (meth) acrylic acid derivative monomers, and, as for the usage-amount of these diene type core shell polymers, 10-30 mass parts is more preferable. If it is less than 5 parts by mass, the thixotropic property may be insufficient, and if it exceeds 40 parts by mass, the viscosity may be too high, resulting in inconvenience in work.

Examples of the elastomer component soluble in (5) (meth) acrylic acid derivative monomer blended in the present invention include acrylonitrile-butadiene-methacrylic acid copolymer, acrylonitrile-butadiene-methyl methacrylate copolymer, and acrylonitrile-butadiene. Examples thereof include styrene-based thermoplastic elastomers such as copolymers, styrene-butadiene copolymers, chlorosulfonated polyethylene, and styrene-polybutadiene-styrene synthetic rubbers, as well as (butadiene) -modified polybutadiene and urethane-based elastomers.

Among these, acrylonitrile-butadiene-methacrylic acid copolymer and acrylonitrile-butadiene copolymer are preferable in terms of solubility and adhesiveness.

The amount of the elastomer component soluble in the (meth) acrylic acid derivative monomer is preferably 5 to 40 parts by mass in total with the diene-based core-shell polymer with respect to 100 parts by mass of the (meth) acrylic acid derivative monomer. -30 mass parts is more preferable.

The resin composition of the present invention can use various paraffins in order to quickly cure the portion in contact with air. Examples of paraffins include paraffin, microcrystalline wax, carnauba wax, beeswax, lanolin, spermaceti, ceresin and candelilla wax. Of these, paraffin is preferred. The melting point of paraffins is preferably 40 to 100 ° C.

As for the usage-amount of paraffin, 0.1-5 mass parts is preferable with respect to 100 mass parts of (meth) acrylic acid derivative monomers. If it is less than 0.1 parts by mass, the portion in contact with air may be hardened, and if it exceeds 5 parts by mass, the adhesive strength may be reduced.

Furthermore, various antioxidants including a polymerization inhibitor can be used for the purpose of improving storage stability. Examples of the antioxidant include p-methoxyphenol, hydroquinone, hydroquinone monomethyl ether, 2,6-ditertiary butyl-p-cresol, 2,2′-methylenebis (4-methyl-6-tertiarybutylphenol), triphenyl Examples thereof include phosphite, phenothiazine, and N-isopropyl-N′-phenyl-p-phenylenediamine. Of these, p-methoxyphenol is preferred.

As for the usage-amount of antioxidant, 0.001-3 mass parts is preferable with respect to 100 mass parts of (meth) acrylic acid derivative monomers. If the amount is less than 0.001 part by mass, the effect may not be achieved, and if it exceeds 3 parts by mass, the curability of the adhesive may be reduced.

As an embodiment of the present invention, preferably, it is used as a two-component adhesive composition. For the two-component type, all the essential components of the adhesive composition of the present invention are not mixed during storage, the adhesive composition is divided into a first agent and a second agent, a polymerization initiator is added to the first agent, Store the reducing agent separately in the two agents. The two-part type is preferable in that it has excellent storage stability. In this case, it can be used as a two-component adhesive composition by applying both agents simultaneously or separately to contact and cure.

The adherend is joined by the adhesive composition of the present invention to produce a joined body. The various materials of the adherend are not limited, such as paper, wood, ceramic, glass, ceramics, rubber, plastic, mortar, concrete, and metal, but when the adherend is metal, it exhibits excellent adhesion.

Hereinafter, the present invention will be described in more detail with reference to experimental examples. The unit of the amount used of each substance is shown in parts by mass. The following compounds were selected as the diene core-shell polymer.

M-1: MBS resin (commercially available) Swelling degree: 10.8 (times)
M-2: MBS resin (commercially available) Swelling degree: 11.5 (times)
M-3: MBS resin (commercially available) Swelling degree: 14.1 (times)
M-4: MBS resin (commercially available) Swelling degree: 7.9 (times)
M-5: MBS resin (commercially available) Swelling degree: 7.2 (times)
The degree of swelling was measured as follows.

[Swelling degree] At 25 ° C., 1 g of a sample is allowed to stand in 100 ml of toluene for 24 hours, and then the gel swollen in toluene is filtered through a 100-mesh wire net (mass A). After 1 minute, the mass B of the swollen gel and the wire mesh was measured, air-dried at room temperature overnight, and then vacuum-dried, and the mass C of the dried gel and wire mesh was measured.
The degree of swelling was determined by the following formula.
Swelling degree (times) = (BA) / (CA)

For each substance described in the table, the following abbreviations were used.
(Abbreviation)
NBR: Acrylonitrile-butadiene copolymer (commercially available)
Phosphate ester: Acid phosphoxyethyl methacrylate

Various physical properties were measured as follows.

[Viscosity and Thixotropic Index] According to JIS K 6838, the viscosity of the adhesive was adjusted to 25 ° C., and using a B-type viscometer, the viscosities of the rotor rotating at 2 and 20 were measured. The thixotropic index was obtained by the following formula.
Thixotropic index = viscosity of 2 revolutions / viscosity of 20 revolutions

[Thread breakability] Two liquids were discharged from a dispenser, and the thread breakage was visually determined.
○: Thread breakage good ×: Thread breakage poor

[Tensile shear bond strength] In accordance with JIS K 6856, an adhesive composition in which equal amounts of the first agent and the second agent are mixed on one side of a test piece (100 mm x 25 mm x 1.6 mm, SECC-D sandblast treatment) is applied. did. After that, the other test piece was immediately put on top of each other and bonded together, and then cured at room temperature for 24 hours. The tensile shear bond strength (unit: MPa) of the sample was measured at a tensile rate of 10 mm / min in an environment of a temperature of 23 ° C. and a relative humidity of 50%.

(Experimental Example 1) Using each diene-based core-shell polymer, a two-pack type adhesive composition shown in Table 1 was prepared, and physical properties were measured. The results are shown in Table 2.

(Experimental example 2) It carried out like Experimental example 1 except having prepared the two-pack type adhesive composition of the composition shown in Table 3. FIG. The results are shown in Table 4.

With the adhesive composition of the present invention, a two-part acrylic adhesive composition having a thixotropic viscosity with good coatability can be obtained. For this reason, an adhesive having good thread breakage at the time of application and excellent workability that does not easily sag even when applied to a vertical surface is obtained, and the industrial advantage is great.

Claims (5)

(1) An acrylic adhesive composition comprising a (meth) acrylic acid derivative monomer, (2) a polymerization initiator, (3) a reducing agent, and (4) a diene core-shell polymer, wherein the diene type A two-part type wherein the core-shell polymer is an MBS resin, is swellable in the (meth) acrylic acid derivative monomer, and has a swelling degree of 9.5 or more in toluene at 25 ° C. Acrylic adhesive composition. The two-component acrylic adhesive composition according to claim 1, wherein the two-component acrylic adhesive composition comprises (5) an elastomer soluble in a (meth) acrylic acid derivative monomer. . The core part of the (4) diene-based core-shell polymer is mainly composed of polybutadiene, and the shell part is mainly composed of a copolymer of styrene and a (meth) acrylic acid derivative. Or the 2 agent type acrylic adhesive composition of Claim 2. (5) The two-component acrylic adhesive composition according to claim 2 or 3, wherein the elastomer soluble in the (meth) acrylic acid derivative monomer is a diene copolymer. A joined body formed by joining with the two-component acrylic adhesive composition according to any one of claims 1 to 4.