JPS63205380A - Epoxy resin adhesive composition - Google Patents

Abstract

PURPOSE:To obtain the title composition which has excellent adhesiveness to an oily surface of a steel plate and excellent mechanical strength, by mixing or reacting an epoxy resin with a liquid diene rubber and a liquid chloroprene rubber, and then incorporating a latent curing agent into the mixture or reaction product. CONSTITUTION:An epoxy resin (e.g., bisphenol A epoxy resin) is mixed or reacted with a liquid diene rubber (e.g., a polybutadiene rubber) and a liquid chloroprene rubber to give a modified epoxy resin. This modified epoxy resin is them mixed with a latent curing agent (e.g., 4,4'-diaminodiphenyl sulfone) to give an objective epoxy-resin-base adhesive composition. The suitable amounts of these components are: 5-30pts.wt. liquid diene rubber, 5-30pts.wt. liquid chloroprene rubber, and 1-20pts.wt. latent curing agent, based on 100pts.wt. epoxy resin. This adhesive composition is suitably used as a structural adhesive.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an epoxy resin adhesive composition, and in particular, to an epoxy resin adhesive composition that is used as a structural adhesive and has excellent adhesion to oil surface steel sheets and good mechanical strength. The present invention relates to adhesive compositions.

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

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

As a result, conventional welding joints suffer from disadvantages such as a decrease in joint strength and deformation of the welded part, and expectations for welt bond joints and adhesive joints are increasing.

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, and the like are known as adhesives having the above performance.

(For example, JP-A-56-136817, JP-A-50-14
No. 2633, No. 50-100125, No. 51-103
No. 937, No. 51-105343, No. 5o-1586
No. 24, No. 54-112959, No. 54-63152
[Problems to be Solved by the Invention] However, acrylic adhesives have problems in aging strength deterioration and workability. On the other hand, as an example of improved epoxy resin adhesives, JP-A-51-103
There is a room-temperature-curing adhesive for oily surfaces made of epoxy resin, phenolic resin, liquid chloroprene rubber, modified amine type curing agent, and metal oxide proposed in Japanese Patent No. 937, but the adhesive strength, especially peel strength, is low. In 5~l.

It was as low as kg/25mm.

[Means for Solving the Problems] Therefore, an object of the present invention is 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. The main purpose is to

According to the present invention, the object is: (A) a modified epoxy resin obtained by blending or reacting (1) an epoxy resin with (2) a diene-based liquid rubber; and (2) a chloroprene-based liquid rubber.

(B) an epoxy resin adhesive composition comprising a latent curing agent;
This is achieved by

That is, as a result of intensive studies aimed at developing an adhesive with good oil-based adhesives and excellent mechanical strength, the present invention has developed an adhesive that can be obtained by mixing or reacting chloroprene liquid rubber and diene liquid rubber. modified epoxy resin,
By incorporating a latent curing agent, the above object has been achieved.

The present invention will be explained in detail below.

The epoxy resin adhesive composition of the present invention is composed of a modified epoxy resin obtained by mixing or reacting an epoxy resin with a diene liquid rubber and a chloroprene liquid rubber, and a latent curing agent.

As the epoxy resin, an epoxy compound having an average of two or more 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
Examples thereof include bisphenol F type epoxy resins, bisphenol F type epoxy resins, novolak type epoxy resins, multifunctional phenol type epoxy resins, and various halogenated epoxy resins. In addition, diglycidyl ether compounds, glycidyl ester type epoxy resins, polyglycol type epoxy resins, cycloaliphatic epoxy resins, hydantoin type epoxy resins, glycidyl amine type epoxy resins, etc. obtained by skin reaction of resorcinol and shrimp herohydrin, etc. can also be used. Epoxy compounds can be used alone or in combination of two or more.

Examples of diene liquid rubbers used for modifying epoxy resins include carboxyl group-terminated acrylonitrile butadiene rubber, polybutadiene rubber, polyisoprene rubber, and polychloroprene rubber, whose molecular weight is 1000.
~7000 liquid rubbers can be mentioned. Particularly preferred are acrylonitrile butadiene rubber and polybutadiene rubber.

The diene liquid rubber contained in the modified epoxy resin is 30
The amount is within % by weight, and if it exceeds this amount, it becomes rubbery and the shear strength decreases. In addition, the diene liquid rubber is 5 to 20
It is preferable that the amount is 10% by weight or more, and the effect of its addition is further improved by using it in an amount of 10% by weight or more.

Representative products of these diene-based liquid rubbers include LYCAR CTBN 1300X.
8 Hiker (Hycar) CT B N 130
0x 13 Hiker (Hycar) CTBN 2
000x162 (all of the above are B, F, manufactured by Guttrich) NISSOPB C-100O NISSOPB C-2000 (both manufactured by Nippon Soda ■) Poly bd R-45MA (manufactured by Idemitsu Petrochemicals), and the like.

The amount of chloroprene liquid rubber contained in the modified epoxy resin is within 30% by weight, and if it exceeds this amount, it becomes rubbery and the shear strength decreases. The amount of chloroprene liquid rubber is preferably 5 to 20% by weight, particularly 5 to 20% by weight.
By using more than % by weight, the effect of its addition is further improved. These chloroprene liquid rubbers have a molecular weight of about 1,000 to 3,000. especially,
The chloroprene liquid rubber preferably has an alkylzantate group at the end; hydroxyl or amino groups do not have this effect. Representative products of these chloroprene liquid rubbers include Denka LCR-XA 50.
.

Examples include Denka LCR-XA 100 (both manufactured by Denki Kagaku Kogyo Co., Ltd.).

These epoxy resins, diene-based liquid rubber, and chloroprene-based liquid rubber may be mixed in a predetermined ratio, and in order to avoid phase separation, they are reacted at 140 to 160°C for 3 to 4 hours, and then defoamed. Good too.

Next, as the latent curing agent, those commonly used as curing agents for epoxy resins are used. For example, guanidine derivatives, triazine derivatives, 4,4'-diaminodiphenylsulfone, acid hydrazide compounds, N, N'
-dialkyl urea derivatives, N,N'-dialkyl thiourea derivatives, etc., and one or a mixture of two or more of these may be used.

The amount of the latent curing agent to be blended may be selected from 1 to 20 parts by weight, preferably from 5 to 15 parts by weight, based on 100 parts by weight of the modified epoxy resin. If it is less than 1 part by weight, the adhesive strength will not be developed due to insufficient curing, and if it exceeds 20 parts by weight, it will become brittle and the adhesive strength will decrease.

The epoxy resin adhesive of the present invention includes the above-mentioned (A) and (
B) It can be prepared by blending components in a predetermined ratio, and if necessary, known additives 1 such as fillers (calcium carbonate, clay, silica, carbon black, metal powder), pigments, flame retardants, leveling agents may be added. Agents, thickeners, etc. may be added.

The mixing of the modified epoxy resin and the curing agent and the addition of various additives can be carried out using various mixing devices. Examples of mixing devices used for such purposes include rolls, kneaders, etc. −, extruder, etc.

[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.

(Example 1) 100 parts by weight of bisphenol A type epoxy resin (trade name: Epicote 828, manufactured by Yuka Shell Epoxy Co., Ltd.) and carboxyl group-terminated nitrile-butadiene rubber (trade name:
5 parts by weight of Hiker CTBN1300x8, B, F, manufactured by Gutdrich) and alkylzantate-terminated chloroprene rubber (trade name: Denka LCRXA-50,
After mixing and blending 15 parts by weight of dicyandiamide (manufactured by Denki Kagaku Kogyo ■), 7 parts by weight of dicyandiamide, 2 parts by weight of trimethylurea, and 20 parts by weight of silica powder, an adhesive was prepared. Its physical property values are shown in the table.

(Example 2) 70 parts by weight of bisphenol A epoxy resin (product name: Epicoat 828, manufactured by Yuka Shell Epoxy Co., Ltd.) and bisphenol A epoxy resin (product name: Epicoat 100)
1. After heating and mixing 30 parts by weight of carboxyl-terminated nitrile-rutadiene rubber (manufactured by Yuka Shell Epoxy Co., Ltd.),
Product name: Hiker CTBN 1300x8, B,
F, manufactured by Gutdrich) and 10 parts by weight of alkyl xanthate-terminated chloroprene rubber (trade name: Denka LCRX)
After mixing and blending 10 parts by weight of A-100 (manufactured by Denki Kagaku Kogyo ■), 7 parts by weight of dicyandiamide, 2 parts by weight of trimethylurea, and 20 parts by weight of silica powder were mixed to prepare an adhesive. Its physical property values are shown in the table.

(Example 3) 100 parts by weight of bisphenol A type epoxy resin (trade name: Epicote 828, manufactured by Yuka Shell Epoxy Co., Ltd.) and carboxyl group-terminated nitrile-butadiene rubber (trade name:
15 parts by weight of Hiker CTBN1300x8, B, F, manufactured by Gutdrich) and alkylzantate-terminated chloroprene rubber (trade name Nidenka LCRXA-50)
, manufactured by Denki Kagaku Kogyo Co., Ltd.) after heating and reacting,
After degassing at 10 mm Hg and 50°C, 7 parts by weight of dicyandiamide, 2 parts by weight of trimethylurea, and 2 parts by weight of silica powder were added.
An adhesive containing 0 parts by weight was prepared. The physical property values are shown in the table.

(Comparative Example 1) 100 parts by weight of bisphenol A type epoxy resin (trade name: Epicote 828, manufactured by Yuka Shell Epoxy Co., Ltd.) and carboxyl group-terminated nitrile-butadiene rubber (trade name:
After uniformly mixing 15 parts by weight of Hiker CTBN1300x8, B, F, manufactured by Gudrich, an adhesive was prepared by blending 7 parts by weight of dicyandiamide, 2 parts by weight of trimethylurea, and 20 parts by weight of silica powder. Its physical property values are shown in the table.

(Comparative Example 2) 100 parts by weight of bisphenol A type epoxy resin (trade name: Epicote 828, manufactured by Yuka Shell Epoxy Co., Ltd.) and alkylzantate-terminated chloroprene rubber (trade name: Denka LCRXA-50, manufactured by Denki Kagaku Kogyo ■ Co., Ltd.) After uniformly mixing 15 parts by weight of dicyandiamide, 2 parts by weight of trimethylurea, and 20 parts by weight of silica powder, 1
I also created an adhesive. Its physical property values are shown in the table.

(Comparative Example 3) 100 parts by weight of bisphenol A epoxy resin (product name: Epicote 828, manufactured by Yuka Shell Epoxy Co., Ltd.) and hydroxyl group-terminated chloroprene rubber (product name: Denka LCRC)
E-50, manufactured by Denki Kagaku Kogyo Co., Ltd.) and 10 parts by weight of carboxyl group-terminated nitrile-butadiene rubber (trade name: Hiker CTBN 1300x8, B, F, manufactured by Gudrich Co., Ltd.) were uniformly mixed, and cycyandiamide was added. An adhesive was prepared by blending parts by weight of door, 2 parts by weight of trimethylurea, and 20 parts by weight of silica powder. Its physical property values are shown in the table.

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.
The lap length is 12.5 mm between the steel plates, and the adhesive thickness is 0.15 mm.
Adhesive was applied to mm and cured at 1800C for 120 minutes. The test was conducted using a Tensilon tensile testing machine manufactured by Toyo Baldwin Co., Ltd. at a tensile speed of 5 mm/min.
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 prepared by curing at 0°C for 20 minutes. The test was carried out using a Tensilon tensile testing machine manufactured by Toyo Baldwin Co., Ltd. at a tensile speed of 200.
It was performed at mm/min.

In addition, the physical property test for oil-surfaced steel plates is similar, but the steel plate is dipped in anti-corrosion oil (Metal Guard #831).
An adhesion test piece was prepared by leaving it for a while.

As is clear from 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.

That is, according to the epoxy resin adhesive composition of the present invention, the tensile shear strength at room temperature is 250 kg/c.
It was confirmed that the adhesive had good oil surface adhesion strength of 18 kg/25 mm or more and a T-peel strength of 18 kg/25 mm or more.

On the other hand, as shown in the comparative example, carboxyl group-terminated nitrile-butadiene rubber (Hiker CTBN130Dx8
, B, F, manufactured by Guttrich) or alkylzanthate-terminated chloroprene rubber (Denka LCRXA-100, manufactured by Denki Kagaku Kogyo)
The peel strength of epoxy resin modified by
kg g 725 mm or less, tensile shear strength 230
It can be seen that the adhesive strength is low, ie, less than kg/cm 2 .

In other words, the effect of the present invention is that two diene-based liquid rubbers, nitrile-butadiene rubber and chloroprene-based liquid rubber, are used.
It can be seen that it is obtained by modifying an epoxy resin with various elastomers.

[Effects of the Invention] As explained above, the epoxy resin adhesive composition of the present invention has good adhesion to oil-surface steel plates and excellent mechanical strength, and is extremely useful as a structural adhesive. It is something.

Claims (4)

[Claims] (1) (A) Blending (a) epoxy resin with (b) diene-based liquid rubber and (c) chloroprene-based liquid rubber,
Alternatively, an epoxy resin adhesive composition comprising a reacted modified epoxy resin and (B) a latent curing agent. (2) (a) For 100 parts by weight of epoxy resin, (b)
5 to 30 parts by weight of diene liquid rubber, (c) 5 to 30 parts by weight of modified epoxy resin, and 1 to 2 parts by weight of (B) latent curing agent.
The epoxy resin adhesive composition according to claim 1, which contains 0 parts by weight. (3) (b) The diene liquid rubber has a molecular weight of 1000 to 7.
The epoxy resin adhesive composition according to claim 1 or 2, which is a butadiene polymer having a carboxyl group at the end of 000 or an acrylonitrile-butadiene copolymer. (4) The epoxy resin adhesive composition according to claim 1 or 2, wherein the chloroprene liquid rubber (c) is a polymer having a molecular weight of 1,000 to 4,000 and having an alkylzantate group at the end.