JPH0245587A - Epoxy resin adhesive composition - Google Patents

Abstract

PURPOSE:To obtain the title composition being excellent in adhesion to steel plate having oil face as structural adhesive and excellent in mechanical strength by blending a specific modified epoxy resin with an imidazole based curing agent at a specific ratio. CONSTITUTION:The aimed composition obtained by blending (A) 100 pts.wt. modified epoxy resin obtained by reacting (i) an epoxy compound component (provided that amount of diene based liquid rubber component in the component is >=35wt.%) containing an epoxy compound modified with a diene based liquid rubber having carboxyl groups at the ends and having 1000-7000 molecular weight with (ii) an urethane prepolymer obtained by reacting a polyetherpolyol having 500-3000 molecular weight with a polyisocyante compound with (B) 0.5-20 pts.wt. imidazole based curing agent such as 2-phenyl-4,5- dihydroxymethylimidazole.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to an epoxy resin adhesive composition, and particularly to a resin adhesive composition that is used as a structural adhesive and has excellent adhesiveness to oil-surface steel plates.

[Prior Art] Structural adhesives are used in a wide range of industrial fields such as aviation, space, vehicles, ships, architecture, civil engineering, electricity, and electronics.

In recent years, thin-walled steel plates, laminated steel plates, and the like have been used to reduce the weight of structural members such as steel plates and aluminum, which have traditionally been used in these fields.

As a result, conventional welded joints have had disadvantages such as a decrease in joint strength and deformation of the welded part, and expectations are increasing for weld pond joints and adhesive joints.

Industrially, it would be economically advantageous if the process of removing press oil, anti-corrosion oil, etc., could be omitted, but there are also parts that are difficult to remove in the removal process. Oil surface adhesion is an essential condition for adhesion of such parts.

Epoxy resin adhesives, acrylic adhesives, polyurethane adhesives, etc. are known as adhesives having the above-mentioned performance (for example, Japanese Patent Application Laid-Open No. 60-235
No. 877, No. 54-26000, No. 60-20688
No. 2, 2nd issue, No. 49-97052, No. 50-35232,
Publications such as No. 54-86562).

[Problems to be solved by the invention] However, acrylic adhesives have problems such as deterioration of hot plating strength and workability, and polyurethane adhesives have problems such as poor oil adhesion and water resistance. There was a problem. On the other hand, as an improved example of epoxy resin adhesives, an adhesive composition made of a urethane-modified epoxy resin proposed in JP-A-54-26000 is known, but it has excellent adhesive strength. The adhesion to oil surfaces could not be said to be sufficient.

rl,′! [Means for solving the lVB point] Therefore, the present invention aims to provide an epoxy resin adhesive composition that has good adhesion to oil-surface steel plates as a structural adhesive and has excellent mechanical strength. This is the main purpose.

According to the present invention, the purpose is to obtain a compound having a molecular weight of 1000 containing a carboxyl group at the two terminals of component A.
An epoxy compound component containing at least one type of epoxy compound modified with a diene liquid rubber having a molecular weight of 500 to 3,000 (however, the amount of the diene liquid rubber component in the epoxy compound component is within 35% by weight);
An epoxy characterized by containing a modified epoxy resin obtained from a urethane prepolymer obtained by reacting a polyether polyol with a polyisocyanate compound, and Component B: 0.5 to 20 parts by weight of an imidazole curing agent. This is achieved using a resin adhesive composition.

That is, as a result of extensive autopsy aimed at developing an adhesive with good oil surface adhesion and excellent mechanical strength, the present invention has developed a modified epoxy resin obtained by reacting a rubber modified epoxy resin with a urethane prepolymer. The above object was achieved by reacting with an imidazole curing agent.

The present invention will be explained in detail below.

Component A blended into the adhesive composition of the present invention contains at least one epoxy compound modified with a diene liquid rubber having a terminal carboxyl group and a molecular weight of too much to 7,000.
This is a modified epoxy resin made by reacting epoxy compounds of various types with a urethane prepolymer obtained by reacting a polyether polyol with a molecular weight of 500 to 3,000 and a polyisocyanate compound.

This component A may consist only of the above-mentioned modified epoxy compound, or may be a mixture of the above-mentioned modified epoxy compound and unmodified epoxy compound.

As the epoxy compound, an epoxy compound having an average number of epoxy groups in the molecule, which is used as a component of ordinary epoxy resin adhesives, is used. Examples of such epoxy compounds include bisphenol A type epoxy resins.

Examples include bisphenol F-type epoxy resins, novolac-type epoxy resins, polyfunctional phenol-type epoxy resins, and various halogenated epoxy resins. In addition, diglycidyl ether compounds obtained by the reaction of resorcinol and evohalohydrin, glycidyl ester type epoxy resins, polyglycol type epoxy resins, cycloaliphatic epoxy resins, hydanto-in type epoxy resins, glycidylamine type epoxy resins, etc. can also be used. Can be done. Epoxy compounds can be used alone or as a mixture of 2M or more.

Examples of diene liquid rubbers having terminal carboxyl groups used for modification of epoxy compounds include carboxyl group-terminated acrylonitrile butadiene rubber, polybutadiene rubber, polyisoprene rubber, polychloroprene rubber, etc., and their molecular weights are between too much and 7,000. Liquid rubber can be mentioned. In particular, representative products that are preferably made of acrylonitrile/lylbutadiene rubber or polybutadiene rubber include Hycar CTBN 1300X8
Hiker (Hycar) CTBN 1300X1
3 Hiker (Hycar) CTBN 2000X
162 (all of the above are B, F, manufactured by Guttrich) N
ISSOPB C-100O, NISSOPB C-2000 (all manufactured by Nippon Soda v4), Poly bd R-45MA (manufactured by Idemitsu Petrochemical ■), and the like.

The amount of diene liquid rubber contained in component A is within 35% by weight, and if it exceeds this amount, it becomes rubbery and the shear strength decreases. Note that the diene liquid rubber contained in component A is preferably 5 to 25% by weight. In particular, by using diene-based liquid rubber with a concentration of 11% or more,
The effect of its addition is further increased by -1-)I.

The reaction between the epoxy compound and the carboxyl group-terminated diene liquid rubber is usually carried out at 80 to 200°C, preferably at 100°C.
Performed at 70°C.

Polyols used in the preparation of the urethane prepolymer in component A include polyether polyols and polyester polyols, and polyether polyols are particularly preferred. Polyether polyols may be those commonly used in polyurethane synthesis; Specific examples thereof include, but are not limited to, the compounds listed below.

In other words, ring-opening polymers and copolymers of cyclic oxides such as ethylene oxide, propylene oxide, and butylene oxide, and cyclic compounds such as oxycyclobutane and tetrahydrofuran, alkylene oxides with basic catalysts and polyhydric alcohols such as glycol and glycerol, or A so-called polyoxyalkylene glycol obtained by polymerization in the coexistence of a primary monoamine is used.

Among the above polyether polyols used in the present invention, preferred examples include polyoxytetramethylene glycol and polyoxypropylene glycol.

The molecular weight of the polyether polyol used in the present invention is preferably 500 to 3000, particularly preferably 800 to 2000,
If the molecular weight is less than 500, the adhesive strength will not improve, and if it exceeds 3000, the oil surface adhesion will decrease.

Next, the polyisocyanate compound for preparing the urethane prepolymer in component A is a compound having a plurality of incyanate groups in one molecule, such as hexamethylene diisocyanate.

2. Aliphatic or alicyclic diisocyanate compounds such as 4-diisocyanate-1-methylcyclohexane, 2,6-diisocyanate-1-methylcyclohexane, diisocyanatecyclobutane, tetramethylene diisocyanate, xylylene diisocyanate, dicyclohexylmethane diisocyanate In addition, 2,4-tolylene diisocyanate, tolylene-2,6-diisocyanate.

Diphenylmethane-4,4'-diisocyanate.

3-methyldiphenylmethane-4,4-diisocyanate, phenylene diisocyanate, chlorophenylene-
2,6-diisocyanate, naphthalene-1,5-disocyanate, diphenyl 4°,4°-diisocyanate, 1,3.5-)lyisobrobylbenzine-2
, 4-diincyanate, and diphenyl ether diisocyanate may be used alone or in combination.

Polyisocyanates preferably used in the present invention include 2.4-) lylene diisocyanate, diphenylmethane-4,4°-diisocyanate, xylylene diisocyanate, 2. Flt-tolylene diisocyanate is mentioned.

In order to obtain a urethane prepolymer having an isocyanate group at the end of the molecule, a general synthesis method used when synthesizing a urethane prepolymer is applied to the method of making the polyether polyol and polyisocyanate react. It is obtained by a method in which a polyol is sequentially added to a polyisocyanate having an excess molar ratio compared to the polyol.

In preparing the urethane prepolymer in the present invention, it is particularly desirable to react 0.95 to 1.1 molecules of a polyisocyanate compound per 1 hydroxyl group in the polyether polyol; if this ratio is less than 0.95, the oil surface The adhesive strength decreases, and when it exceeds 1.1, the adhesive strength decreases.

The reaction between the rubber-modified epoxy resin in component A and the urethane prepolymer may be carried out at 100-150° C. for 2 to 3 hours, and the reaction is continued until the incyanate group disappears.

The urethane prepolymer contained in component A is.

It is preferable to react 2 to 40 parts by weight, preferably 5 to 30 parts by weight, per 100 parts by weight of the rubber-modified epoxy resin. If it exceeds 40 parts by weight, the oil surface adhesion will decrease, and if it is less than 2 parts by weight, the adhesive strength will decrease. does not improve.

Next, a solid imidazole curing agent is used as the imidazole curing agent used as the B component. For example, 2
-Methylimidazole, 2-undecyl imitazole,
2-heptadecyl imitazole, 2-phenylimidazole, ■-cyanethyl-2-methylimidazole, l
-cyanoethyl-2-undecylimidazole 1-cyanoethyl-2-undecylimidazole trimetate, -cyanoethyl-2-phenylimidazolium trimetate, 2-methylimidazolium incyanurate, 2-phenylimidazolium incyanurate Nurate,
2,4-diamino-6-[:2methylimitazolyl(
1)]-]Ethyl-s-triazine 2,4-diamino-
6-[2ethyl-4methylimitasolyl(1)]-]
Ethyl-s-triazine2,4-diamino-6-[2undecylimidazolyl-(1)]-]ethyl-3-riazine, 2-phenyl-4,5-dihydroxymethylimidazole, 2-phenyl-4methyl-5-hydroxy Methylimidazole, ■-cyanoethyl-2-phenyl-4
,5-di(cyanoethoxymethyl)imitasole, l-
Examples include dodecyl-2methyl-3-benzylimidazolium chloride and 1,3-dibenzyl-2-methylimidazolium chloride. It can also be used in combination with a latent curing agent commonly used for epoxy resins.

The latent curing agent is, for example, a guanidine derivative.

Examples include triazine derivatives, 4,4'-diaminodiphenylsulfone, acid hydrazide compounds, N,N'-dialkyl urea derivatives, N,N'-dialkylthiourea derivatives, and acid anhydrides.

The blending amount of the imidazole curing agent is 100% of the epoxy resin.
0.5 to 20 parts by weight, preferably 1 to 1 parts by weight
It may be selected at 0 parts by weight.

If it is less than 0.5 parts by weight, curing will be insufficient and no adhesive strength will be developed, and if it exceeds 20 parts by weight, it will become glassy and brittle.

The epoxy resin adhesive of the present invention can be prepared by blending the above-mentioned A and B components in a predetermined ratio, and if necessary, known additives such as fillers (calcium carbonate, clay, silica, carbon black , metal powder), pigments, flame reagents, leveling agents, thickeners, etc. may be added.

In addition, component A (modified epoxy resin) and component B (curing agent)
Mixing with other ingredients and addition of various additives can be carried out using various mixing devices, and examples of mixing devices used for such purposes include rolls, niegu, extruders, etc. can.

[Examples] Hereinafter, the present invention will be explained in more detail with reference to Examples and Comparative Examples, but it will be clear that the present invention is not limited to these Examples.

Examples 1 to 8 Rubber modified epoxy resin A-1 was prepared by charging bisphenol A type epoxy resin and liquid rubber in the proportions shown in Table 1 into a reaction vessel and reacting at 140 to 160°C for 3 hours. ~A-2 was prepared.

Regarding the urethane prepolymer, 2.4-tolylene diisocyanate was charged into a reaction vessel at the proportions shown in Table 2, and a predetermined amount of polyether polyol was added dropwise.
Urethane prepolymers B-1 to B-4 were prepared by reacting at 0 to 120°C for 3 hours. In addition, in Table 2, P
TG is polytetramethylene ether glycol (manufactured by Sakudogaya Chemical Co., Ltd.), 1000, 1500, 2000
each indicates the molecular weight. Moreover, PPG is polypropylene ether glycol (B Hon Yushi Kagaku Co., Ltd.), and 1300 indicates a molecular weight of -.

Next, the reaction between the rubber-modified epoxy resin and the urethane prepolymer is performed by heating the rubber-modified epoxy resin and the urethane prepolymer until they become liquid, and then mixing them at 100 to 120°C.
The reaction was carried out for 3 hours until the infrared absorption of the incyanate group disappeared, and modified epoxy resins C-1 to G-8 were prepared.

Next, 100 parts by weight of C-1-C-8 modified epoxy resin, 5 parts by weight of dicyandiamide, and 2-phenyl-4,5
-Dihydroxymethylimida tool 5 parts, silica 5 parts
Parts by weight and 30 parts by weight of aluminum powder were mixed and blended in a kneader and then defoamed to produce epoxy resin adhesives of Examples 1 to 8. The physical property values are shown in Table 4.

100 parts by weight of C-5 modified epoxy resin, 5 parts by weight of dicyandiamide, 5 parts by weight of 2-heptadecyl imidazole, 5 parts by weight of silica powder, and 30 parts of aluminum powder! ! Example 9 was obtained by mixing and blending the components and degassing.

After mixing and blending 100 parts by weight of C-3 modified epoxy resin, 5 parts by weight of dicyandiamide, 5 parts by weight of 1-Schiff/Lf-2 undecyl imida tool, 5 parts by weight of silica powder, and 30 parts by weight of aluminum powder, defoaming was performed. This was referred to as Example 1O.

Comparative Example 1 Bisphenol A epoxy resin (Epicote 828,
50 parts by weight of a urethane-modified epoxy resin obtained by reacting 14 parts of 100 (manufactured by Yuka Shell Epoxy Co., Ltd.) with 230 parts by weight of urethane prepolymer B-2 at 140°C to 160°C for 6 hours, 100 parts by weight of Epicoat 828, and liquid nitrile. −
Butadiene rubber (Hiker CTBN 1300X1
3.B.

F, manufactured by Gutdrich) 30 parts by weight at 140°C to 160°C
50 parts by weight of a rubber-modified epoxy resin reacted for 3 hours at °C was mixed with 5 parts by weight of dicyandiamide and 5 parts by weight of 2-phenyl 4.5-dihydroxymethylimidazole in the same manner as in the previous example.

An adhesive of Comparative Example 1 was prepared by blending 5 parts by weight of silica powder and 30 parts by weight of aluminum powder. The physical property values are shown in Table 4.

Comparative Example 2 Bisphenol A epoxy resin (Epicote 828,
After reacting 100 parts by weight (manufactured by Yuka Shell Epoxy Co., Ltd.) with 1 part by weight of urethane prepolymer B-220 at 100°C to 120°C for 3 hours, this urethane-modified epoxy resin 1
00 parts by weight, Hiker CTBN 1300X
15 parts by weight of No. 13 was reacted at 140°C to 160°C for 3 hours. To this were added 5 parts by weight of dicyandiamide and 5 parts by weight of 2-phenyl-4,5-dihydroxymethylimidazole.

An adhesive of Comparative Example 2 was prepared by blending 5 parts by weight of silica powder and 30 parts by weight of aluminum powder. The physical property values are shown in Table 4.

Comparative Example 3 Bisphenol A epoxy resin (Epicote 828,
100 parts by weight (manufactured by Yuka Shell Epoxy Co., Ltd.) and 220 parts by weight of urethane prepolymer B-2 at 140°C to 160°C.
100 parts of urethane-modified epoxy resin reacted for hours, 2 parts of Dicyanschiff 515, 2-phenyl-4,5
An adhesive of Comparative Example 3 was prepared by blending 5 parts by weight of -dihydroxydimethylimidazole, 5 parts by weight of silica powder, and 30 parts by weight of aluminum powder. The physical property values are shown in Table 4.

Comparative Example 4 Bisphenol A epoxy resin (Epicote 828,
Yuka Shell Epoxy Co., Ltd.) 100 parts by weight and Hiker C
TBN 1300X13 10 parts by weight at 140℃~1
After reacting at 60°C for 3 hours, 5 parts by weight of dicyandiamide, 541 parts of 2-phenyl-4,5-dihydroxymethylimitazole! ffi part, 5 parts by weight of silica powder, and 30 parts by weight of aluminum powder were blended to prepare an adhesive of Comparative Example 4. The physical property values are shown in Table 4.

The test method for physical property values is as follows.

■Shear strength: Measured in accordance with JIS K6850. The test piece has a thickness of 1.6 mm according to JIS G3141.
Wrap length 12.5 mm, adhesive thickness 0 on the steel plate tllll of
．． The adhesive was applied to 15mno and cured at 180'C for 20 minutes. The test was carried out using a Tensilon tensile testing machine manufactured by Toyo Baldwin Co., Ltd., with a tensile strength of 5 mm/ff1 inch.
I did it.

■Peel strength: A T-peel test was conducted in accordance with JIS K6854.

The test piece was made by applying adhesive between 0.8 mm thick steel plates according to JIS G3141 to a bond thickness of 0.15 mm.
It was cured at 0°C for 920 minutes. The test was carried out using a Tensilon tensile testing machine manufactured by Toyo Baldwin Co., Ltd. at a tensile speed of 20.
The test was performed at 0 mm/win.

In addition, physical property tests on oil-surfaced steel plates were conducted in the same manner, but adhesive test pieces were prepared by dipping the steel plates in antirust oil (Metal Guard #831, manufactured by Mobil Petrochemical Co., Ltd.) and leaving them for 24 hours.

As is clear from the results of the above examples and comparative examples,
The epoxy resin adhesive composition of the present invention exhibits excellent adhesive strength even on oil-surfaced steel plates.

For example, time opening +1i! ? In the case of the urethane-modified epoxy resin adhesive proposed in Publication No. 54-26000, the highest tensile shear strength is 290 kg/cr.
n'', while the tensile shear strength of the oil surface steel plate is 265k
g/crn', the decrease was large.

On the other hand, according to the epoxy resin adhesive composition of the present invention, the tensile shear strength of 285 kg/crn' or more, the tensile shear strength of oil-face steel plate of 275 kg/ctr1 or more, and the T-peel strength of oil-face steel plate of 19 kg/725 mm or more. The results were obtained.

Furthermore, compared to the case where liquid nitrile-butadiene rubber modified epoxy resin is modified with urethane prepolymer as in the present invention, liquid nitrile-butadiene rubber as in Comparative Examples 1 and 2.4 is
The peel strength is 8 for blending modified epoxy resin with butadiene rubber and urethane modified epoxy as in Comparative Example 3.
It showed a relatively low value of ~15kg725mm.

(Hereinafter, blank spaces) Table 1 Table 2 Table [Effects of the invention] As explained above, the epoxy resin adhesive composition of the present invention has good adhesion to oil-faced steel plates and has excellent mechanical strength. Therefore, it is extremely useful as a structural adhesive.

Patent applicant: Ube Industries Co., Ltd.

Claims (3)

[Claims] (1) (A) Molecular weight 10 with carboxyl group at the end
an epoxy compound component containing at least one type of epoxy compound modified with a diene liquid rubber having a molecular weight of 00 to 7,000 (however, the amount of the diene liquid rubber component in the epoxy compound component is within 35% by weight); and a molecular weight of 500 to 3,000. Contains a urethane prepolymer obtained by reacting a polyether polyol with a polyisocyanate compound, 100 parts by weight of a modified epoxy resin obtained by reacting the following, and (B) 0.5 to 20 parts by weight of an imidazole curing agent. An epoxy resin adhesive composition characterized by: (2) The epoxy resin adhesive according to claim 1, wherein the urethane prepolymer in component (A) is 2 to 40 parts by weight based on 100 parts by weight of the epoxy compound modified with a diene liquid rubber component. Composition. (3) The epoxy compound modified with the diene liquid rubber component in component (A) is
2. The epoxy resin adhesive composition according to claim 1, wherein the diene liquid rubber is an epoxy compound reacted and modified in an amount of 5 to 25 parts by weight.