JPH06264046A - Epoxy adhesive composition - Google Patents

Abstract

PURPOSE:To improve the tensile shear strength and peel strength after cure of this compsn. without increasing the viscosity by compounding an epoxy resin. a curative, and a particulate crosslinked rubber having pyridyl groups. CONSTITUTION:This adhesive compsn. is prepd. by compounding an epoxy resin (e.g. a bisphenol A epoxy resin) (A), a particulate crosslinked rubber having pyridyl groups (B), and a curative (e.g. triethylenetetramine) (C). Pref., component B is a random copolymer obtd. by copolymerizing a polymerizable unsatd. compd. having a pyridyl group, such as 2-vinylpyridine or 4-vinylpyridine, with a copolymerizable unsatd. compd., such as acrylonitrile, butadiene, or divinylbenzene, and has a gel content of 50-100%. A suitable compounding ratio (pts.wt.) of A:B:C is 100:(3-60):(2-200).

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an epoxy adhesive composition, and more particularly to an epoxy adhesive composition in which fine particles of a particulate crosslinked rubber having a pyridyl group are dispersed in an epoxy resin.

[0002]

2. Description of the Related Art In recent years, there has been proposed a method for improving flexibility and the like of an epoxy resin by blending a crosslinked rubbery random copolymer latex having a functional group such as a carboxyl group with an epoxy resin (Japanese Patent Laid-Open No. HEI-2) -117948 gazette).
According to this method, since the fine particles of the crosslinked rubber are dispersed in the epoxy resin without being dissolved, the increase in viscosity due to the addition of the rubber component is small, and a cured product having high toughness can be obtained. It is said to have advantages such as obtaining an excellent epoxy adhesive. However, there is a problem that the viscosity of the composition increases because the crosslinked rubber reacts with the epoxy group at room temperature depending on the type of functional group.
In addition, a relatively large amount of crosslinked rubber needs to be blended in order to exhibit sufficient adhesive properties, which causes a problem that the viscosity of the blend becomes high.

[0003]

SUMMARY OF THE INVENTION An object of the present invention is to provide an epoxy adhesive composition in which the viscosity does not increase and the flexibility of the epoxy resin is improved.
As a result of intensive studies, the present inventors have found that it is effective to blend a particulate crosslinked rubber having a pyridyl group with an epoxy resin, and have completed the present invention based on this finding.

[0004]

According to the present invention, the following (1) to (8) are provided. (1) An epoxy adhesive composition prepared by blending an epoxy resin (a), a particulate crosslinked rubber (b) having a pyridyl group and a curing agent (c). (2) An epoxy adhesive composition prepared by mixing 100 parts by weight of an epoxy resin (a), 3 to 60 parts by weight of a particulate crosslinked rubber having a pyridyl group (b) and 2 to 200 parts by weight of a curing agent (c). . (3) The epoxy adhesive composition according to the above (1) or (2), wherein the gel content of the particulate crosslinked rubber having a pyridyl group is 50 to 100%. (4) The particle diameter of the crosslinked rubber having a pyridyl group is 30
(1) which is from 0 to 5000 angstroms
To (3) the epoxy adhesive composition. (5) The epoxy adhesive according to any one of (1) to (4), wherein the particulate crosslinked rubber having a pyridyl group is a random copolymer with 2-vinylpyridine or 4-vinylpyridine, acrylonitrile, butadiene and divinylbenzene. Composition. (6) The particulate crosslinked rubber having a pyridyl group is a random copolymer of 2-vinylpyridine or 4-vinylpyridine, acrylonitrile, butadiene and divinylbenzene, and the copolymerization amount of acrylonitrile and butadiene is (15 / 85) to (55/45), the epoxy adhesive composition according to the above (1) to (5). (7) The epoxy adhesive composition according to any of (1) to (6) above, wherein the particulate crosslinked rubber having a pyridyl group is obtained by emulsion polymerization using a polymeric emulsifier.

The epoxy resin (a) used in the present invention is a liquid at room temperature which is usually used as a component of an epoxy adhesive, and examples of such an epoxy resin include:
Examples thereof include bisphenol A type epoxy resin, bisphenol F type epoxy resin, novolac type epoxy resin, glycidyl ester type epoxy resin, glycidyl amine type epoxy resin, cycloaliphatic epoxy resin and hydantoin type epoxy resin. The epoxy resins may be used alone or in combination of two or more.

The particulate crosslinked rubber (b) having a pyridyl group used in the present invention is a polymerizable unsaturated compound having a pyridyl group and a copolymer with another polymerizable unsaturated compound copolymerizable therewith. Therefore, it is a particulate crosslinked rubbery random copolymer having a particle size of usually 300 to 5000 angstroms, preferably 500 to 2000 angstroms when dispersed in an epoxy resin, and a gel content of 50 to 100%. Here, the gel content means 1 g of the particulate crosslinked rubbery random copolymer and 100 ml of methyl ethyl ketone.
The weight of the insoluble matter was measured after immersing in the solution and allowing it to stand at room temperature for 24 hours.

Examples of the polymerizable unsaturated compound having a pyridyl group used include 2-vinylpyridine, 3-vinylpyridine, 4-vinylpyridine, 2-methyl-5-vinylpyridine and 5-ethyl-2-vinylpyridine. 2-vinyl pyridine and 4-vinyl pyridine are preferable from the viewpoint of adhesive properties.

Other polymerizable unsaturated compounds used include conjugated dienes such as butadiene, isoprene and chloroprene; vinyl cyanide such as acrylonitrile and methacrylonitrile; methyl acrylate, ethyl acrylate, butyl acrylate and acrylic acid. Acrylic acid esters such as 2-ethylhexyl; methacrylic acid esters such as methyl methacrylate, ethyl methacrylate, and butyl methacrylate; aromatic vinyl compounds such as styrene, vinyltoluene, and α-methylstyrene, and the like. A combination of acrylonitrile and butadiene is preferred.

The polymerizable unsaturated compound having these pyridyl groups and other polymerizable unsaturated compounds are appropriately selected,
They can be used alone or in combination of two or more. The copolymerization amount of the polymerizable unsaturated compound having a pyridyl group in the crosslinked random copolymer is usually 0.5 to 4
It is 0% by weight, preferably 1 to 20% by weight. When the copolymerization amount of the polymerizable unsaturated compound having a pyridyl group is less than 0.5% by weight, the effect of improving the physical properties after curing the epoxy resin composition is not sufficient, which is not preferable. If it exceeds 40% by weight, the composition viscosity tends to increase, which is not preferable. Further, when the other polymerizable unsaturated compound is a combination of acrylonitrile and butadiene, acrylonitrile and butadiene are (15/85) to (55).
/ 45)% by weight is preferable.

The gel in the particulate crosslinked rubber having a pyridyl group used in the present invention may be one formed during the polymerization reaction by controlling the polymerization temperature, but it is usually prepared by copolymerizing a crosslinking monomer. It is preferably formed. Examples of such a crosslinkable monomer include compounds having a plurality of double bonds in the molecule, and specific examples thereof include divinylbenzene, diallyl phthalate, ethylene glycol dimethacrylate, and trimethylolpropane trimethacrylate.

The copolymerization amount of the crosslinkable monomer in the crosslinked random copolymer is usually 0.1 to 20% by weight, preferably 0.5 to 10% by weight. When the amount of the crosslinkable monomer used is less than 0.1% by weight, only a copolymer having a gel content of less than 50% can be obtained, and therefore the particles of the particulate crosslinked rubber dissolve without being uniformly dispersed in the epoxy resin. Then, the viscosity of the composition remarkably increases, which is not preferable. On the other hand, if it exceeds 20% by weight, the effect of improving the physical properties after curing the epoxy resin composition is not sufficient, which is not preferable.

The method of producing the particulate crosslinked rubber having a pyridyl group used in the present invention is not particularly limited, but usually,
A radical polymerization initiator such as a peroxide-based initiator or a redox-based initiator as a polymerization initiator in the presence of an emulsifier, a polymerizable unsaturated compound having a pyridyl group, another polymerizable unsaturated compound and the crosslinkable monomer. Emulsion polymerization using
It is recommended that the latex has a particle size of about 300 to 5000 angstrom.

The curing agent (c) used in the present invention is not particularly limited as long as it is usually used as a curing agent for epoxy adhesives, but is usually ethylenediamine, diethylenetriamine, triethylenetetramine, tetraethylenepentamine. Aliphatic polyamines such as; aromatic polyamines such as metaphenylenediamine, diaminodiphenylmethane, diaminodiethyldiphenylmethane; secondary and tertiary amines such as benzyldimethylamine, triethylenediamine, triethanolamine, piperidine, polyamidoamine; anhydrous phthalates Acid anhydrides such as trimellitic anhydride, pyromellitic anhydride, maleic anhydride, succinic anhydride, tetrahydrophthalic anhydride, and methyltetrahydrophthalic anhydride; imidazole, 2-methylimidazole, 2 Ethyl-4-methylimidazole,
Imidazole derivatives such as 2-phenylimidazole, 2-undecylimidazole and 2-heptadecylimidazole; dicyandiamide and its derivatives; organic acid hydrazides such as adipic hydrazide; 3- (p-chlorophenyl) -1,1-dimethylurea, 3- (3,4-
Urea derivatives such as dichlorophenyl) -1,1-dimethylurea; polymercaptan type curing agents; phenolic resins,
Examples thereof include methylol group-containing compounds such as urea resins and melamine resins; polyisocyanates, aromatic diazonium salts, aromatic sulfonium salts and the like.

In the method for producing an epoxy adhesive composition of the present invention, usually, a latex of a particulate crosslinked rubber having a pyridyl group is blended with an epoxy resin to obtain a particulate crosslinked rubber having a pyridyl group in the epoxy resin. Disperse, then
A method of adding a curing agent may be mentioned. As a method for dispersing the particulate crosslinked rubber having a pyridyl group in the epoxy resin, for example, a method in which the epoxy resin and the latex are stirred under a shearing force, the separated water is removed, and drying is performed;
A method in which an epoxy resin emulsified or suspended in a water system is mixed with the latex, followed by coagulation to remove water and drying; coagulation of the latex and mixing a coagulation product before drying with an epoxy resin, and then water. A method of removing and drying; a particulate crosslinked rubber having a pyridyl group obtained by coagulating and drying the latex is dispersed in an organic solvent under forced stirring, and this is mixed with an epoxy resin, and then the solvent is removed. And a method of drying. Further, the particulate crosslinked rubber can be dispersed in the epoxy resin by using an ordinary hot roll, intermixer, kneader, extruder or the like.

When a latex obtained by emulsion polymerization using a polymeric emulsifier is used as the particulate crosslinked rubber having a pyridyl group used in the epoxy adhesive of the present invention, the latex is coagulated and washed. It is preferable because it can be blended in the epoxy resin without doing so and does not adversely affect the adhesive physical properties of the epoxy adhesive.

The term "polymeric emulsifier" used herein means at least one of a carboxyl group or an acid anhydride group in an unsaturated carboxylic acid or its anhydride and an addition copolymer with another monomer copolymerizable therewith. A part is a water-soluble salt forming a salt. As the unsaturated carboxylic acid or its anhydride, acrylic acid, methacrylic acid, crotonic acid, fumaric acid, maleic acid, itaconic acid, fumaric acid anhydride, maleic anhydride, itaconic anhydride, monobutyl maleate, monooctyl maleate, itacone Examples thereof include monooctyl acid.
Further, as other monomers copolymerizable therewith, aromatic vinyl compounds such as styrene, α-methylstyrene, vinyltoluene, pt-butylstyrene and chlorostyrene; methyl acrylate, ethyl acrylate, Propyl acrylate, butyl acrylate, isobutyl acrylate,
Acrylic acid esters such as n-amyl acrylate, isoamyl acrylate, n-hexyl acrylate, 2-ethylhexyl acrylate, n-octyl acrylate, 2-hydroxyethyl acrylate, hydroxypropyl acrylate; methyl methacrylate, methacryl Ethyl acid, propyl methacrylate, butyl methacrylate, isobutyl methacrylate, n-amyl methacrylate, isoamyl methacrylate, n-hexyl methacrylate, 2-ethylhexyl methacrylate, n-octyl methacrylate, 2-hydroxyethyl methacrylate, Methacrylic acid esters such as hydroxypropyl methacrylate; acrylamide compounds such as acrylamide, N-methylol acrylamide, N-butoxymethyl acrylamide; methacrylamide, N Methylol methacrylamide, N-
Methacrylamide compounds such as butoxymethyl methacrylamide and glycidyl acrylate, glycidyl methacrylate, allyl glycidyl ether and the like can be mentioned.

The weight average molecular weight of the addition copolymer is 200.
The acid number is 0 to 20000, preferably 3000 to 15000, and the acid value is 50 to 400, preferably 80 to 300. An epoxy adhesive composition containing a particulate crosslinked rubber having a pyridyl group, which is obtained when a salt of an addition copolymer having a weight average molecular weight of less than 2000 is used as an emulsifier, is not preferable because the peel strength is reduced. . Further, when a salt of the addition copolymer having a weight average molecular weight of more than 20,000 is used as an emulsifier, the viscosity of the latex of the particulate crosslinked rubber having a pyridyl group may be increased and may cause aggregation during polymerization. It is not preferable. When the acid value of the addition copolymer is less than 50, it is difficult to neutralize it to make it water-soluble, and conversely, the acid value is 40 or less.
If it exceeds 0, the amount of the neutralizing agent to be used increases and the water resistance of the epoxy adhesive decreases, which is not preferable.

The amount of the polymeric emulsifier used is usually 5 parts by weight based on 100 parts by weight of the total weight of the polymerizable unsaturated compound having a pyridyl group, another polymerizable unsaturated compound and the crosslinkable monomer. ~ 40 parts by weight. By using an amount of the polymeric emulsifier in this range, it is possible to produce a latex of a particulate crosslinked rubber having a stable pyridyl group without using any builder or other emulsion stabilizer that adversely affects the adhesive properties. it can.

As a method of dispersing the pyridyl group-containing particulate crosslinked rubber obtained by using such a polymeric emulsifier in an epoxy resin, a latex of the pyridyl group-containing particulate crosslinked rubber is coagulated and washed. A method of blending with an epoxy resin without removing the water contained in the latex, and the like. According to the method illustrated,
A composition is obtained in which fine particles of the particulate crosslinked rubber having a pyridyl group are uniformly dispersed in the epoxy resin. The method of removing water is not particularly limited, and examples thereof include a method of heating the mixture of the latex and the epoxy resin at 40 to 120 ° C. under normal pressure or reduced pressure while stirring.

The compounding amount of each component used in the epoxy adhesive composition of the present invention is usually 100 parts by weight of the epoxy resin (a).
With respect to parts by weight, 3 to 60 parts by weight, preferably 5 to 40 parts by weight of a particulate crosslinked rubber having a pyridyl group, and 2 to 200 parts by weight of a curing agent (c), preferably 2 to
It is 100 parts by weight. If the amount of the particulate crosslinked rubber having a pyridyl group is less than 3 parts by weight, the effect of improving the flexibility of the epoxy resin cannot be obtained, which is not preferable. Further, if it exceeds 60 parts by weight, the viscosity of the epoxy adhesive composition increases, which is not preferable.

The epoxy adhesive composition of the present invention may optionally contain additives such as a curing accelerator, a reactive diluent, a non-reactive diluent, a filler, a pigment and an antiaging agent. You can Such an epoxy adhesive composition can be used not only as an adhesive but also as a coating agent, a molding material and the like.

[0022]

EXAMPLES The present invention will be described in more detail with reference to the following examples. The parts and% in the examples and comparative examples are based on weight unless otherwise specified. Reference Example 1 100 parts of isopropyl alcohol was charged into a reactor and 80
100 parts of a monomer compound consisting of 62% of methyl methacrylate, 16% of ethyl acrylate and 22% of methacrylic acid and 4 parts of 2,2-azobis-2,4-dimethylvaleronitrile as a radical polymerization initiator. /12.5 parts of toluene were continuously added to the reactor over a period of 4 hours. Then keep the reactor temperature at 80 ° C for 2 hours,
The polymerization reaction was completed. Then, the reactor was cooled to room temperature, ammonia water containing ammonia corresponding to the neutralization equivalent and 400 parts of water were added, and then the reactor was heated to 90 ° C. or higher to distill off isopropyl alcohol and excess water. Thus, an aqueous polymer emulsifier solution having a nonvolatile content of 25% was obtained.

Reference Example 2 A reactor was charged with 100 parts of the polymer emulsifier aqueous solution (25% active ingredient concentration) obtained in Reference Example 1, 100 parts of soft water, and 100 parts of a monomer mixture having the composition shown in Table 1. Polymerization was carried out at 50 ° C. with 0.15 part of potassium persulfate. 0.05 part of potassium persulfate was added in three portions at the start of the reaction, after 5 hours and after 10 hours. After 16 hours, a latex of a particulate crosslinked rubber having a pyridyl group was obtained with a conversion of 90% or more. Table 1 shows the average particle size and gel content of the latex. The average particle size of the latex was measured using a submicron particle sizer, Auto Dilute Model 370 (manufactured by Nicomp) (unit: angstrom). The unit of gel content is%.

[0024]

[Table 1]

Examples 1 to 4, Comparative Examples 1 to 5 Epicoat 828 (bisphenol A type epoxy resin,
100 parts of Yuka Shell Epoxy Co., Ltd.) and the latex obtained in Reference Example 2 in an amount such that the solid content thereof is in the ratio shown in Table 2 with respect to Epicoat 828, and charged into a flask equipped with a stirrer. By vacuum distillation at 60 ° C. with stirring, an almost transparent epoxy resin composition in which fine particles of a particulate crosslinked rubber having a pyridyl group are uniformly dispersed in an epoxy resin is prepared, and its viscosity is obtained. Was measured. Next, in the epoxy resin composition, a curing agent (dicyandiamide), a filler (manufactured by Shiragika U Shiraishi Calcium Co.) and a fine powder silica (Aerosil 200) having the composition shown in Table 2 were added.
(Manufactured by Nippon Aerosil Co., Ltd.) to prepare an epoxy adhesive, and the adhesive properties were evaluated as follows. The results are shown in Table 2.

(1) Viscosity measurement Viscometer for high viscosity (B8H type, rotor N, manufactured by Tokyo Keiki Co., Ltd.)
o. 7. Rotor speed: 1.0 rpm), 25
The viscosity at ° C was measured (unit: cp). (2) Tensile shear strength The adhesive is applied to a 0.8 mm-thick steel plate defined in JIS G-3141 degreased with toluene, and similar steel plates are superposed so as to have an adhesion area of 15 mm × 10 mm, and 180 Heat at 60 ℃ for 60 minutes to cure, JIS K
According to -6850, it measured at 23 degreeC and the speed of 5 mm / min (unit: kg / cm < ² >). (3) T-type peel strength A sample was prepared in the same manner as (2) above (bonding area 25 mm x 1
50 mm), and 5 at 23 ° C according to JISK-6854.
It was measured at a speed of 0 mm / min (unit: kg / 25 m
m).

[0027]

[Table 2]

From the results shown in Table 2, it can be seen that the epoxy adhesive composition of the present invention exhibits excellent adhesive physical properties. On the other hand, when a crosslinked rubber that does not contain a pyridyl group is blended with an epoxy resin, it is necessary to increase the blending amount of the crosslinked rubber in order to obtain the same adhesive physical properties as in the present invention. You can see that it will be higher.

[0029]

As described above, according to the present invention, it is possible to obtain an epoxy adhesive composition which does not increase the viscosity of the adhesive composition and has excellent adhesive physical properties after curing.

Claims (7)

[Claims] 1. An epoxy adhesive composition comprising an epoxy resin (a), a particulate crosslinked rubber having a pyridyl group (b) and a curing agent (c). 2. An epoxy adhesive comprising 100 parts by weight of an epoxy resin (a), 3 to 60 parts by weight of a particulate crosslinked rubber having a pyridyl group (b) and 2 to 200 parts by weight of a curing agent (c). Composition. 3. The gel content of the particulate crosslinked rubber having a pyridyl group is 50 to 100%.
Epoxy adhesive composition. 4. A particulate crosslinked rubber having a pyridyl group,
The epoxy adhesive composition according to any one of claims 1 to 3, which has a particle size of 300 to 5000 angstroms. 5. A particulate crosslinked rubber having a pyridyl group,
The epoxy adhesive composition according to any one of claims 1 to 4, which is a random copolymer of 2-vinylpyridine or 4-vinylpyridine, acrylonitrile, butadiene and divinylbenzene. 6. A particulate crosslinked rubber having a pyridyl group,
A random copolymer of 2-vinylpyridine or 4-vinylpyridine, acrylonitrile, butadiene and divinylbenzene, wherein the copolymerization amount of acrylonitrile and butadiene satisfies (15/85) to (55/45). The epoxy-based adhesive composition according to any one of claims 1 to 5, which is a thing. 7. A particulate crosslinked rubber having a pyridyl group,
The epoxy adhesive composition according to claim 1, which is obtained by emulsion polymerization using a polymeric emulsifier.