JPH03137179A - Adhesive - Google Patents

Abstract

PURPOSE:To obtain an adhesive capable of firmly joining in a short time and useful for joining steel sheets, etc., by dispersing magnetic substance powder in a two-pack type thermosetting resin composed of a liquid epoxy resin containing a bisphenol A type epoxy resin modified with a liquid butadiene- acrylonitrile rubber having carboxyl groups and 3000-4000 molecular weight (CTBN), etc., and polyaminoamide. CONSTITUTION:The objective adhesive, obtained by dispersing (C) magnetic substance powder in a two-pack type thermosetting resin composed of (A) a liquid epoxy resin prepared by adding (ii) 10-70 pts.wt. single or two or more of a bisphenol A type epoxy resin modified with CTBN, a polyalkylene glycol diglycidyl ether and diglycidyl ester of a higher aliphatic dicarboxylic acid having >=300 molecular weight to (i) 100 pts.wt. bisphenol A type or bisphenol F type epoxy resin having 170-2000 epoxy equiv. and (B) a polyaminoamide, having 3.0-60kgf/mm<2> tensile elastic modulus of a cured product and excellent in bonding durability.

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Object of the invention [Field of industrial application] The present invention relates to a high-frequency induction heating adhesive that can form strong bonds in a short time.

The adhesive according to the present invention is mainly used for joining plastics, metals, ceramics, etc. used in the automobile industry or the household appliance industry, and in particular, for joining SMCs reinforced with glass fibers or carbon fibers ( Suitable for joining reinforced plastics such as sheet molding compounds).

[Conventional technology]

Conventionally, as described in U.S. Pat. A high-frequency induction heating joining method is known in which a heating element generates heat by applying a high-frequency magnetic field of several G) [z to heat-join the objects to be joined.

The present inventors have also proposed a high-frequency induction heating bonding method using a thermosetting resin such as an epoxy resin instead of the thermoplastic resin as the bonding medium (Japanese Patent Laid-Open No. 1983-1972-1).
205151).

[Problem to be solved by the invention]

Epoxy resin adhesives are widely used as structural adhesives because they have strong adhesive strength and excellent adhesive durability. Regarding bonding using such epoxy adhesives, there is a demand for shortening the bonding time from industries that perform line production such as the automobile industry, and in order to meet this demand, adoption of high-frequency induction heating bonding method is being considered. There is.

However, the high-frequency induction heating method usually heats only the adhesive without heating the objects to be joined, so if the objects to be joined are steel plates or SMC (sheet molding compound) with a large coefficient of thermal expansion, the bonding interface (With conventional epoxy adhesives, this stress remains and there is a problem in terms of adhesive durability.)

(B) Structure of the Invention [Means for Solving the Problems] As a result of intensive study by the present inventors in order to obtain an adhesive that is capable of strong bonding in a short time and has excellent adhesive durability, the epoxy resin It was discovered that an adhesive mainly composed of 3.0 to 60 kgf/mm'' tensile modulus of cured adhesive has both stress relaxation and heat resistance, and in completing the present invention. It's arrived.

That is, in the present invention, the epoxy equivalent is 170 to 2.00.
The following compound (A) per 100 parts by weight of bisphenol A type or bisphenol F type epoxy resin
A two-component thermosetting resin consisting of a liquid epoxy resin (hereinafter referred to as the main resin) to which 10 to 70 parts by weight of , (B) or (C) (hereinafter collectively referred to as the combined epoxy compound) is added, and polyaminoamide. The tensile modulus of the cured product in which magnetic powder is dispersed is 3.0 to 60 kg f/mm.
” is a high frequency induction heating adhesive.

(A): CTBN-modified bisphenol A type epoxy resin (B): Polyalkylene glycol diglycidyl ether (C) Diglycidyl ester of higher aliphatic dicarboxylic acid having a molecular weight of 300 or more The present invention will be explained in more detail below.

As mentioned above, the main ingredient constituting the high-frequency induction heating adhesive of the present invention is composed of a bisphenol A type or bisphenol F type epoxy resin having an epoxy equivalent of 170 to 2.000 and a combined epoxy compound, and as a whole, it is stable at room temperature. It is a liquid composition.

The ratio of the above-mentioned epoxy resin and the combined epoxy compound in the main ingredient is 10 to 70 parts by weight of the combined epoxy compound per 100 parts by weight of the above-mentioned epoxy resin, preferably 100 parts by weight of the epoxy resin. ! The amount of the epoxy compound used in combination is 20 to 50 parts by weight per fit part.

Specific examples of the epoxy compound used in the present invention are as shown below.

Compound (A): CTBN modified bisphenol A type epoxy resin.

The CTBN-modified bisphenol A type epoxy resin that can be used in the present invention has a carboxyl group and a molecular weight of 3.00.
It is a product obtained by esterifying liquid butadiene-acrylonitrile rubber (herein abbreviated as CTBN) with a molecular weight of 0 to 4,000 and a bisphenol A type epoxy resin. It is obtained by reacting at 170°C for 2 to 3 hours. The preferred amount of acrylonitrile in the CTBN used is 15 to 30-1% from the viewpoint of compatibility with the epoxy resin to be reacted. Further, a preferable reaction ratio of bisphenol A type epoxy resin and CTBN is 20 to 70 parts by weight of CTBN per 100 parts by weight of the epoxy resin.

Compound (B): diglycidyl ether of polyalkylene glycol.

A specific example is the product name DER-73 manufactured by Dow Chemical Company.
2 (Polypropylene glycol diglycidyl ether)
Polyethylene glycol diglycidyl ether, polybutylene glycol diglycidyl ether, etc. can also be used.

Compound (C) A diglycidyl ester of higher aliphatic dicarboxylic acid having a molecular weight of 300 or more.

Examples include diglycidyl ester of dimer acid.

The above compounds (A) to (C) can be used alone or in combination of two or more.

The adhesive of the present invention has a tensile modulus of elasticity of the cured product containing magnetic powder, which will be described later, that is lower than that of epoxy resin adhesives used for other purposes, so that residual stress after adhesion can be quickly alleviated. It is desirable that it be lower than the case, 3.0 to 60
kg f/mn+".

For the purpose of setting the tensile modulus of the cured product within the above range, a plasticizer such as epoxidized soybean oil, dioctyl phthalate or polypropylene glycol may be added to the adhesive, if necessary. Moreover, the above-mentioned combined epoxy compound acts in the direction of lowering the tensile modulus of the cured product.

In the main ingredient, if the amount of the epoxy compound used in combination is less than 10 parts by weight per 100 parts by weight of the epoxy resin, the above-mentioned plasticizer may not be used in excess in order to set the tensile modulus of the cured product within the above range. If the amount exceeds 70 parts by weight, the proportion of epoxy resin decreases relatively and the strong adhesive strength inherent to epoxy resins is not expressed.

Next, the polyaminoamide that acts as a curing agent for the above-mentioned main ingredient will be explained.

As the polyaminoamide in the present invention, fatty acids containing unsaturated double bonds such as linoleic acid or liluic acid,
A mixture of dimerized fatty acids, dimerized fatty acids, tetramerized fatty acids, etc. obtained by heating and polymerization in the presence of a catalyst such as alumina silicate, and ethylenediamine, diethylenetriamine, triethylenetetramine, etc. There is a polyaminoamide obtained by condensing polyethylene polyamide, and preferably has an amine value of 200 to 450.
mgKOH/g polyaminoamide.

The amount of polyaminoamide used is preferably 60 to 90 parts by weight, more preferably 70 to 80 parts by weight, per 100 parts by weight of the main agent. The amount of polyaminoamide is 60
If it is less than part by weight, the residual stress after adhesion will increase,
On the other hand, if it exceeds 90 parts by weight, the heat resistance and water resistance of the adhesive will decrease.

When using amine-based curing agents, acids, and acid anhydride-based curing agents other than polyaminoamides, the volumetric shrinkage rate of the adhesive resin, that is, the ratio at which the volume of the adhesive itself shrinks after curing compared to before curing, is large, resulting in poor adhesion. A large stress is generated afterwards, and the desired adhesive durability cannot be obtained.

When bonding SMC, etc. on a line, an adhesion speed is usually required to complete the adhesion within one minute, but in this case, in the adhesive of the present invention, catechol, pyrogallol and It is preferable to add a phenolic curing accelerator such as polyvinylphenol, and the appropriate amount is 1.0 to 20 parts by weight of the curing accelerator per 100 parts by weight of the polyaminoamide.

The adhesive of the present invention is obtained by adding magnetic powder, which is sensitive to high frequency induction, to the polyaminoamide as the main ingredient and curing agent.

The magnetic powder is preferably a substance that generates heat due to magnetic hysteresis loss or eddy current loss in a high-frequency magnetic field, specifically fine powder with a particle size of 1 micron or less made of iron, nickel, iron oxide, ferrite, etc. moreover,
In a high frequency magnetic field of 100 K) and IMI (z),
Particulate 7-Fez0= is most preferred in terms of efficient heat generation.

The magnetic powder is preferably added to both the main material and the polyaminoamide, and the amount added is the total amount added to both, and is 30 to 150 parts by weight per ff1loo parts by weight of the total organic components in the main material and the polyaminoamide. parts by weight, and more preferably from 50 to 100 parts by weight.

In addition to the above-mentioned components, the adhesive of the present invention may optionally contain ultrafine anhydrous silica particles, a silane coupling agent, and the like. When using SMC as an adherend, silane coupling agents can be used to improve adhesive strength, such as T-glycidoxypropyltrimethoxysilane, etc., can be added to the main agent, and T-aminopropyltriethoxysilane, etc. is used by adding it to polyaminoamide.

The method for preparing the adhesive is to mix the base resin and curing agent separately in order to uniformly disperse the magnetic powder and to prevent air from being drawn in to prevent foaming during heat bonding. 40 to 60 each
It is preferable to heat the mixture to 20°C and knead it for 20 to 60 minutes under a vacuum of 3 to 20 torr while applying a large shearing force. Suitable mixing and kneading machines include a vacuum miller,
Examples include planetary mixers.

Next, the adhesion method will be explained.

The adhesive of the present invention generates heat and increases temperature by high-frequency induction heating,
Cured adhesion is performed. The frequency of the high frequency oscillator used in the present invention is 10K) (z~lOMHz
is suitable, and more preferably from 100 KHz to IMHz in terms of heating efficiency and uniformity of temperature distribution. 1
Below 00KHz, heating efficiency is low and IM]lz
In this case, it is difficult to uniformly heat the adhesive in the surface direction.

The shape of the heating coil connected to the high-frequency oscillator can be the single-turn coil, multi-turn coil, hairbin coil, pancake coil, etc. used in high-frequency induction heating for boat fishing, but it is possible to use a shape in which the adhesive surface is sandwiched between the hairbin coils. Heating is the most efficient method. Furthermore, if the coils cannot be placed on both sides of the bonding surface due to the shape of the adherend, a hairpin coil or pancake coil can be placed on one side for thermal bonding, although the heating efficiency is poor.

[Examples and comparative examples]

Example 1 An adhesive having the following composition was prepared.

(Main agent) - 60 parts by weight of Epicoat 828 (1:190 to epoxy, manufactured by Yuka Shell Epoxy Co., Ltd., bisphenol A type epoxy resin) - 30 parts by weight of CTBN modified bisphenol A type epoxy resin (Note 1) - DER-7325 parts by weight (Epoxy weight 1:315, manufactured by Dow Chemical Company) - Kabox S-65 parts by weight (manufactured by Kao Corporation, epoxidized soybean oil) - WAT-10370 parts by weight (manufactured by Toda Kogyo Co., Ltd., granular T Fc403) - Aerosil # 200 1 part by weight (manufactured by Nippon Aerosil Co., Ltd., ultrafine particulate anhydrous silica) (Note 1) Epicote 828: 100 parts by weight and CTBN 1,
Using 50 parts by weight of 300XI 3 (manufactured by Ube Industries, Ltd.), 1 part of triphenylphosphine (0.3ii) was mixed therewith, and the mixture was reacted at 150° C. for 3 hours.

(Curing agent) Persamide 125 97 parts by weight (manufactured by Henkel Hakusuisha, polyaminoamide, amine value 350 m
gKO) 1/g) ・NUCA-1,1003 parts by weight (manufactured by Nippon Unicar Co., Ltd., γ-aminopropyltriethoxysilane) ・Marcarin Power-M 5 parts by weight (manufactured by Maruzen Sekiyu Co., Ltd.: polyvinylphenol) -WAT-103
70 was mixed with Okibe (manufactured by Toda Kogyo Co., Ltd., granular 1-FeO 0.0) and 2 parts by weight of Aerosil #200 (manufactured by Nippon Aerosil Co., Ltd., ultrafine particulate anhydrous silica), and the above composition was mixed separately as a main ingredient and a curing agent. Planetary at 50°C under 110torr
The mixture was kneaded using a mixer (manufactured by Bengami Seisakusho, model PLM-V-5V) to obtain a two-component epoxy resin adhesive. The main agent and curing agent of this adhesive were weighed at a weight ratio of 17.1:13.5 (resin ratio: 10:8) and thoroughly mixed using a spaticle.

Gel time of the adhesive after mixing these two components at 150°C (when a small amount of adhesive is placed on a hot plate at 150°C and observed while stirring with a spaticle, it is the time until the adhesive loses its stringability. Evaluation) was measured and found to be 22 seconds. Furthermore, when this adhesive was left in an oven at 150°C for 20 minutes, the cured product had a volume shrinkage rate of 1.7% and a tensile modulus of 24.4 (kg f/+++gi”).
Met. Furthermore, the pot life of this adhesive when it was left at room temperature at 25° C. (the maximum time that it could be applied to an adherend while maintaining its paste form) was measured and was approximately 90 minutes.

Next, using this adhesive, a 3 mm thick SMC (manufactured by Takeda Pharmaceutical Company, grade B-12) test piece was
It was adhered to S- according to -6850 to prepare a test piece for measuring tensile shear strength. For bonding, a hairpin type coil with a copper square vibrator with a width of 15mff1 is used, and a high frequency input of 3.5K is used.
Heat bonding was carried out under the conditions of V8, frequency 400, and oscillation time 40 seconds. When the tensile shear strength of the five adhesive test pieces thus obtained was measured, the average value was 66 (
kg/ci). In addition, the tensile shear strength of a similarly prepared test piece after 10 cycles of cold and heat from 30°C to 80°C was 63 (kg/cJ), and the tensile shear strength at 80'C hot was 43 (kg/cd). Ta.

Example 2 (Main agent) Ebiko 1-828 70, W placement part 5
T-2PG (Note 2) 20 parts by weight Dioctyl phthalate 5 parts by weight Phenyl glycidyl ether 5 parts by weight WAT-10370 parts by weight Aerosil #200 1 part by weight (curing agent) Persamide 140 (Note 3) 97 parts by weight A-1
100 3 Okibe WAT-103
70 parts by weight Aerosil #200 2 parts by weight Marca Linker M 10 parts by weight (Note 2) Long chain dicarboxylic acid diglycidyl ester, epoxy equivalent 32
0. Manufactured by Mazai Oil Co., Ltd.

(Note 3) Amine value 380mgKOH/g, manufactured by Henkel Hakusuisha.

A main agent and a curing agent having the above composition were prepared in the same manner as in Example 1, and then mixed at a resin weight ratio of 10:8 to obtain an adhesive.

Example 3 (Main ingredient) Ebiko) 828 70 parts by weight CTB
N-828 10 parts by weight DER-732
20 parts by weight γ-glycidoxypropyltrimethoxysilane 3 parts by weight Box S-65 parts by weight WA, T-10370 parts by weight Aerosil #200 i parts by weight (curing agent) Persamide 140 80 parts by weight Amino group-containing butadiene acrylonitrile Rubber 20 parts by weight WAT-10370 parts by weight Aerosil #200 2 parts by weight Pyrogallol 5 parts by weight In the same manner as in Examples 1 and 2, an adhesive consisting of the main ingredient and curing agent having the above composition was prepared.

Comparative Example 1 (Main ingredient) Epicoat 828 90 parts by weight DER-
7325 parts by weight Force Box S-65 parts by weight VAT-10370 parts by weight Aerosil #200 1 part by weight (curing agent) Persamide 12597 parts by weight A-11003 parts by weight WAT-10370 parts by weight Aerosil #200 2 parts by weight Pyrogallol 5 parts by weight An adhesive consisting of the main ingredient and curing agent having the above composition was prepared in the same manner as in each Example.

The adhesive of this comparative example is DER, which is an epoxy compound used in combination.
The proportion of -732 in the main ingredient is Epicote 828i10
The amount is 5.6 parts by weight per 0 parts by weight, which is below the scope of the present invention.

The adhesives of Examples 2 to 3 and Comparative Example 1 were also evaluated for physical properties similar to those of Example 1, and the results are shown in Table 1 together with the results of Example 1.

(C) Effects of the Invention The adhesive of the present invention has strong adhesive strength unique to epoxy resin adhesives, and since high-frequency induction heating is applied as a curing means, it can be bonded for a short time. By making the adhesive composition unique,
The residual stress after bonding is small, and the bonding durability is excellent as evidenced by the results of thermal cycle tests.

Therefore, it is extremely effectively used when bonding SMC, steel plates, etc. on lines in the automobile industry, etc., where short-time bonding is required.

Claims (1)

[Claims] 1. Bisphenol A type or bisphenol F type epoxy resin 1 having an epoxy equivalent of 170 to 2,000
Per 00 parts by weight, the following compound (A), (B) or (
A two-component thermosetting resin consisting of a liquid epoxy resin to which 10 to 70 parts by weight of C) is added and polyaminoamide,
The tensile modulus of the cured product in which magnetic powder is dispersed is 3.0.
High frequency induction heating adhesive with ~60kgf/mm^2. (A): CTBN-modified bisphenol A type epoxy resin (B): Polyalkylene glycol diglycidyl ether (C): Diglycidyl ester of higher aliphatic dicarboxylic acid with a molecular weight of 300 or more