JP2001019929A - One-pack type epoxy resin-based adhesive - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a one-pack type epoxy resin-based adhesive for providing a cured material having excellent thermal impact resistance suitable for bonding an iron core such as an ignition coil especially requiring thermal impact resistance to a case. SOLUTION: This one-pack type epoxy resin-based adhesive is obtained by compounding 100 pts.wt. of a resin component composed of (A) 20-70 wt.% of a liquid urethane modified epoxy resin having a chelate forming ability, (B) 6-20 wt.% of crosslinked rubber fine particle having 0.05-0.5 μm average particle diameter and (C) 10-74 wt.% of a liquid biphenol type epoxy resin with (D) 2-20 pts.wt. of a latent curing agent and (E) 0.1-20 pts.wt. of a curing promoter.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a novel one-component epoxy resin-based adhesive, and more particularly, it is suitably used for bonding an iron core of an ignition coil and a case, particularly where thermal shock resistance is required. The present invention relates to a one-pack type epoxy resin adhesive capable of obtaining a cured product having excellent thermal shock resistance when thermally cured.

[0002]

2. Description of the Related Art Conventionally, as an adhesive between an iron core such as an ignition coil and the like which requires thermal shock resistance and a case,
For example, a one-pack type epoxy resin adhesive containing asbestos for improving thermal shock resistance, or a rubber-modified epoxy resin obtained by reacting rubber and epoxy resin, and a needle-like inorganic filler mixed with this as a main component One-component epoxy resin adhesives and the like are known. However, the use of asbestos and needle-like inorganic fillers is being restricted due to environmental pollution, and one-component epoxy resin-based adhesives containing a rubber-modified epoxy resin obtained by reacting rubber and epoxy resin. However, although the toughness of a cured product obtained by heat-curing the cured product is improved, the glass transition point is lowered, and there is a disadvantage that it cannot be used for applications requiring thermal shock resistance.

[0003]

SUMMARY OF THE INVENTION Under such circumstances, the present invention provides a heat-shock resistant material suitable for use in bonding an iron core of an ignition coil to a case, which is particularly required to have heat-shock resistance. Another object of the present invention is to provide a one-pack type epoxy resin adhesive which gives a cured product having excellent physical properties.

[0004]

Means for Solving the Problems The inventors of the present invention have developed a one-pack type epoxy resin-based adhesive which gives a cured product exhibiting excellent thermal shock resistance without blending asbestos or a needle-like inorganic filler. As a result of intensive studies, a liquid urethane-modified epoxy resin having chelating ability, crosslinked rubber fine particles of a specific average particle size, a liquid bisphenol-type epoxy resin, a latent curing agent, and a curing accelerator were each mixed at a specific ratio. It has been found that the above objects can be achieved by blending, and the present invention has been completed based on this finding.

That is, the present invention relates to (A) 20 to 70% by weight of a liquid urethane-modified epoxy resin capable of forming a chelate, and (B) 6 to 20% by weight of crosslinked rubber fine particles having an average particle diameter of 0.05 to 0.5 μm. % Of (C) 2 to 20 parts by weight of a latent curing agent and (E) 0.1 to 100 parts by weight of a resin component composed of 10 to 75% by weight of a liquid bisphenol type epoxy resin. An object of the present invention is to provide a one-pack type epoxy resin adhesive containing 20 parts by weight.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the one-pack type epoxy resin adhesive of the present invention, it is necessary to use a liquid urethane-modified epoxy resin having chelate forming ability as the component (A). This compound is prepared by adding a diisocyanate compound such as tolylene diisocyanate, isophorone diisocyanate, diphenylmethane diisocyanate, dimethylhexamethylene diisocyanate or the like to a bisphenol A having at least one hydroxyl group in one molecule.
It is manufactured by reacting a bisphenol type epoxy resin such as a type epoxy resin and a bisphenol F type epoxy resin with a polyol having a polyaminocarboxylic acid group such as ethylenediaminetetraacetic acid, a condensed phosphoric acid skeleton, and the like. The liquid urethane-modified epoxy resin having chelating ability may be used alone or in combination of two or more.

Next, in the adhesive of the present invention, it is necessary to use crosslinked rubber fine particles as the component (B).
The crosslinked rubber fine particles are, for example, acrylic rubber, butadiene rubber, silicone rubber, ethylene-propylene rubber,
It is made of a crosslinked rubber such as acrylonitrile-butadiene rubber. These may be used alone or as a mixture of two or more, but from the viewpoint of dispersibility in an epoxy resin and heat cycle resistance of a cured product, they are composed of a crosslinked acrylonitrile-butadiene rubber. Fine particles are preferred.

The average particle diameter of the crosslinked rubber fine particles is 0.0
It needs to be in the range of 5 to 0.5 μm. When the average particle size is less than 0.05 μm, the viscosity of the adhesive becomes high, and the handleability is poor. When it exceeds 0.5 μm, it is difficult to obtain a cured product having sufficient heat cycle resistance. Considering the viscosity of the adhesive and the heat cycle resistance of the cured product, the preferred range of the average particle size is 0.05 to
0.2 μm.

In the adhesive of the present invention, it is necessary to use a liquid bisphenol type epoxy resin as the component (C). This liquid bisphenol-type epoxy resin is a liquid that shows a liquid state at an average ordinary temperature, that is, 25 ° C., and can be arbitrarily selected from known bisphenol-type epoxy resins that are liquid at ordinary temperature. However, from the viewpoint of workability, for example, dispenser application workability, the epoxy equivalent is particularly preferably 120 to
A low viscosity liquid bisphenol F type epoxy resin in the range of 240 is preferred. In the present invention, this liquid bisphenol type epoxy resin may be used alone,
Two or more kinds may be used in combination.

[0010] The component (A) in the adhesive of the present invention,
Regarding the mixing ratio of the component (B) and the component (C),
The compounding amount of the liquid urethane-modified epoxy resin as the component (A) is in the range of 20 to 70% by weight based on the amount of the resin component, that is, the total amount of the components (A), (B), and (C). It is necessary. If the amount is less than 20% by weight, a cured product having desired physical properties such as sufficient elongation, low elasticity and deformation follow-up property cannot be obtained, and if it exceeds 70% by weight, the viscosity of the adhesive becomes high and the handling property becomes high. In addition, the reactivity decreases. Taking into account the elongation of the cured product, the viscosity and reactivity of the adhesive, and the like, the preferred amount of the component (A) is in the range of 30 to 60% by weight.

The compounding amount of the crosslinked rubber fine particles of the component (B) may be in the range of 6 to 20% by weight based on the total amount of the components (A), (B) and (C). is necessary. When the amount is less than 6% by weight, a cured product having sufficient heat cycle resistance cannot be obtained, and when it exceeds 20% by weight, the viscosity of the adhesive becomes too high, and the dispersion in the epoxy resin becomes difficult. Considering the heat cycle resistance of the cured product and the dispersibility in the epoxy resin, the preferred amount of the component (B) is in the range of 6 to 15% by weight.

On the other hand, the compounding amount of the liquid bisphenol type epoxy resin of the component (C) is in the range of 10 to 75% by weight based on the total amount of the components (A), (B) and (C). It is necessary. When this amount is less than 10% by weight, the viscosity of the adhesive becomes high, and the handleability deteriorates.
The reactivity decreases, and if it exceeds 75% by weight, a low elastic modulus,
A cured product having desired physical properties such as heat cycle resistance cannot be obtained. The viscosity and reactivity of the adhesive and the elastic modulus of the cured product,
Considering heat cycle resistance and the like, the preferred amount of the component (C) is in the range of 30 to 65% by weight.

In the adhesive of the present invention, the crosslinked rubber fine particles of the component (B) and the liquid bisphenol-type epoxy resin of the component (C) are dispersed in the component (C) to form a sea-island structure. In such a state, it is preferable to include it in the adhesive. Thereby, even if the toughness is improved, a heat-resistant cured product in which the glass transition point does not decrease can be obtained.

In the adhesive of the present invention, examples of the latent curing agent used as the component (D) include dicyandiamide, urea compounds, organic acid hydrazide compounds, polyamine salt compounds, amine adduct compounds, and the like. These may be used alone or in combination of two or more, but dicyandiamide is preferred from the viewpoint of the adhesive strength of the cured product and the pot life of the adhesive.

The compounding amount of the latent curing agent of the component (D) is 2 parts per 100 parts by weight of the resin component, that is, 100 parts by weight of the total amount of the components (A), (B) and (C). ~ 2
It must be in the range of 0 parts by weight. When the amount is less than 2 parts by weight, the curing speed of the adhesive is low and the adhesive strength of the cured product is insufficient. When the amount exceeds 20 parts by weight, the glass transition temperature of the cured product is remarkably lowered, and the heat resistance is poor. Become.
Considering the curing speed, the adhesive strength of the cured product, the heat resistance, and the like, the preferred amount of the component (D) is in the range of 4 to 15 parts by weight.

In the adhesive of the present invention, the curing accelerator used as the component (E) includes, for example, a urea compound,
Phosphine compounds, imidazole compounds and the like can be mentioned, and these may be used alone or in combination of two or more, but from the viewpoint that the glass transition temperature is not lowered and the pot life is long. , Methylenediphenylbisdimethylurea and toluenebisdimethylurea are preferred, and methylenediphenylbisdimethylurea is particularly preferred.

The amount of the curing accelerator (E) is as follows:
The amount of the resin component, that is, 0.1 to 2 parts by weight based on 100 parts by weight of the total amount of the components (A), (B) and (C)
It must be in the range of 0 parts by weight. If this amount is 0.
If the amount is less than 1 part by weight, the curing speed of the adhesive is low, and if it exceeds 20 parts by weight, the glass transition temperature of the cured product is lowered. Considering the curing speed and heat resistance of the cured product, this (E)
The preferred amount of the components is in the range of 0.5 to 20 parts by weight.

The one-pack type epoxy resin-based adhesive of the present invention preferably contains an inorganic filler having an effect of improving heat resistance, hardening distortion resistance and the like, if desired. Examples of the inorganic filler include calcium carbonate, silica, alumina, aluminum hydroxide, magnesium oxide, talc, mica, clay, and the like. These may be used alone or in combination of two or more. However, calcium carbonate is preferable because it can be easily dispersed in an adhesive. The compounding amount of the inorganic filler is selected in a range of usually not more than 200 parts by weight, preferably not more than 100 parts by weight based on 100 parts by weight of the total of the components (A), (B) and (C). . Considering the viscosity of the adhesive and clogging of the dispenser nozzle, the average particle diameter is usually 0.1.
１００100 μm, preferably 0.5 to 10 μm in average particle size.

The one-component epoxy resin-based adhesive of the present invention preferably contains a thixotropic agent which has an effect of improving workability such as dripping prevention. As the thixotropic agent, ultrafine silica, ultrafine alumina,
Ultrafine calcium carbonate or the like can be used alone or as a mixture. The amount of the thixotropic agent is
Total amount of component (A), component (B) and component (C) 100
1 to 50 parts by weight, and preferably 2 to 50 parts by weight,
It is selected in the range of 30 parts by weight. Further, the one-pack type epoxy resin-based adhesive of the present invention may contain, if necessary, various conventional additives such as a reactive diluent and a flame retardant, as long as the object of the present invention is not impaired. , An antifoaming agent, a surfactant, a coloring agent, and the like.

The method for preparing the one-pack type epoxy resin adhesive of the present invention is not particularly limited. For example, the essential components (A) to (E), the desired inorganic filler, and the thixotropic agent Can be prepared by homogeneously mixing various additives, but from the viewpoint of workability and thermal shock resistance of the cured product, the component (B) is previously added to the component (C) as described above.
It is advantageous to disperse the components and mix them with other components in a sea-island structure.

[0021]

The one-pack type epoxy resin adhesive of the present invention has a heat cycle resistance,
Excellent heat resistance, high cured product with a glass transition temperature of 125 ° C or higher, good adhesion between metals such as cold-rolled steel sheets, for example, SPCC and silicon steel sheets, and plastics such as polybutylene terephthalate, and thermal shock resistance As an adhesive from which a cured product having excellent properties can be obtained, it is particularly suitably used for bonding an iron core of an ignition coil to a case, which requires vibration resistance when heated.

[0022]

Next, the present invention will be described in more detail by way of examples, but the present invention is not limited to these examples. The physical properties of the adhesive and its cured product were measured by the following methods.

(1) Viscosity Using an EHD type viscometer at 25 ° C. and a rotational speed of 2.5 r
It was measured in pm. (2) Gelation time A gel plate based on JIS C-2104 is kept at 150 ° C., and 0.4 ml of the sample is placed on the plate. That is, the time (s) until gelation was measured. (3) Flexural strength and flexural modulus According to JIS K-6911, width 10 mm, height 4 m
m at 100 ° C. for 1 hour and further at 120 ° C. for 3 hours.
The bending test was performed under the conditions of ° C, a load speed of 3 mm / min, and a span of 64 mm, and the average value of the measured values is shown. (4) Glass transition temperature For a test piece obtained by curing a sample (15 mm × 5 mm × 5 mm) at 100 ° C. for 1 hour and further at 120 ° C. for 3 hours, using a thermomechanical analyzer manufactured by Mac Science,
The measurement was performed under the conditions of a heating rate of 5 mm / min and a load of 10 g, an inflection point was obtained, and this was defined as a glass transition temperature. (5) Heat cycle test An iron spring washer having a diameter of 20 mm was placed in a petri dish having a diameter of 50 mm, and a sample was further placed so as to incorporate the washer.
And then left at room temperature to remove the cured product from the petri dish to prepare a test piece. This test piece was repeatedly subjected to one cycle of processing of holding at -30 ° C for 1 hour and then holding at 120 ° C for 1 hour. X. (6) Shear adhesive strength 100 mm x 25 mm based on JIS K-6850
A 1.6 mm SPCC-SD steel plate is polished with a # 150 polishing cloth, and then applied to a degreased one so as to have a single overlap of 12.5 mm. , And the shear adhesive strength was measured in an atmosphere of 25 ° C under a load speed of 50 mm / min, and the average value of the measured values of five samples was shown. (7) T peel adhesion strength According to JIS K-6854, SPCC is used as the adherend.
Using an SD steel plate (150 mm × 25 mm × 0.5 mm) degreased, a sample was applied and cured at 120 ° C. for 3 hours to prepare a test piece. This test piece 5
Each piece was tested under the conditions of a temperature of 25 ° C. and a load speed of 50 mm / min, and the peel adhesion strength was measured.

The specific contents of each component used are shown below. (1) Liquid urethane-modified epoxy resin having chelate forming ability “Adeka Resin EPU-7” manufactured by Asahi Denka Kogyo KK
8-11 ", epoxy equivalent 230 (2) Liquid urethane-modified epoxy resin (having no chelate-forming ability)" ADEKARESIN EPU- "manufactured by Asahi Denka Kogyo KK
6 ", epoxy equivalent 235 (3) Liquid acrylonitrile-butadiene copolymer rubber-modified epoxy resin (having no chelate-forming ability)" ADEKARESIN EPR-1 "manufactured by Asahi Denka Kogyo KK
508 ", epoxy equivalent 290 (4) Crosslinked NBR fine particles Crosslinked acrylonitrile-butadiene copolymer rubber fine particles,
JSR Corporation, trade name "FX-501", average particle diameter of primary particles 0.07 μm (5) Bisphenol F type epoxy resin Yuka Shell Epoxy Co., Ltd. trade name, "Epicoat 80"
7 ", epoxy equivalent 167 (6) Dicyandiamide Yuka Shell Epoxy Co., Ltd., trade name" Epicure DI
(CY15), average particle diameter 7-10 μm (7) Methylenediphenylbismethylurea AC I Japan Co., Ltd., trade name “Omicure 52” (8) Calcium carbonate Bibihoku Powder Chemical Industry Co., Ltd., product Name "Softon 1200",
Average particle size 1.80 μm

Example 1 and Comparative Examples 1 to 8 One-part epoxy resin adhesives having the compositions shown in Tables 1 and 2 were prepared, and their performance was evaluated. Table 1 shows the results.

[0026]

[Table 1]

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[Procedure amendment]

[Submission date] September 21, 1999 (September 9, 1999
1)

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] Claim 1

[Correction method] Change

[Correction contents]

[Procedure amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0005

[Correction method] Change

[Correction contents]

That is, the present invention relates to (A) 20 to 70% by weight of a liquid urethane-modified epoxy resin capable of forming a chelate, and (B) 6 to 20% by weight of crosslinked rubber fine particles having an average particle diameter of 0.05 to 0.5 μm. % Of (C) 2 to 20 parts by weight of a latent curing agent and (E) 0.1 to 100 parts by weight of a resin component composed of 10 to 74% by weight of a liquid bisphenol type epoxy resin (C). An object of the present invention is to provide a one-pack type epoxy resin adhesive containing 20 parts by weight.

[Procedure amendment 3]

[Document name to be amended] Statement

[Correction target item name] 0012

[Correction method] Change

[Correction contents]

On the other hand, the compounding amount of the liquid bisphenol type epoxy resin of the component (C) is in the range of 10 to 74% by weight based on the total amount of the components (A), (B) and (C). It is necessary. When this amount is less than 10% by weight, the viscosity of the adhesive becomes high, and the handleability deteriorates.
The reactivity decreases, and if it exceeds 74% by weight, a low elastic modulus,
A cured product having desired physical properties such as heat cycle resistance cannot be obtained. The viscosity and reactivity of the adhesive and the elastic modulus of the cured product,
Considering heat cycle resistance and the like, the preferred amount of the component (C) is in the range of 30 to 65% by weight.

[Procedure amendment 4]

[Document name to be amended] Statement

[Correction target item name] 0014

[Correction method] Change

[Correction contents]

In the adhesive of the present invention, examples of the latent curing agent used as the component (D) include dicyandiamide, organic acid hydrazide compounds, polyamine salt compounds, amine adduct compounds, and the like. Dicyandiamide may be used, or two or more of them may be used in combination, but dicyandiamide is preferred from the viewpoint of the adhesive strength of the cured product and the pot life of the adhesive.

[Procedure amendment 5]

[Document name to be amended] Statement

[Correction target item name] 0023

[Correction method] Change

[Correction contents]

(1) Viscosity Using an EHD type viscometer at 25 ° C. and a rotational speed of 2.5 r
It was measured in pm. (2) Gelation time A gel plate based on JIS C 2104 was kept at 150 ° C., and 0.4 ml of the sample was placed on the plate. That is, the time (s) until gelation was measured. (3) Flexural strength and flexural modulus According to JIS K 6911, width 10 mm, height 4 m
m at 100 ° C. for 1 hour and further at 120 ° C. for 3 hours.
° C, crosshead moving speed 3mm / min, span 6
The bending test was performed under the condition of 4 mm, and the average value of the measured values is shown. (4) Glass transition temperature For a test piece obtained by curing a sample (15 mm × 5 mm × 5 mm) at 100 ° C. for 1 hour and further at 120 ° C. for 3 hours, using a thermomechanical analyzer manufactured by Mac Science,
Measured under the conditions of a heating rate of 5 ° C./min and a load of 10 g,
The inflection point was determined and defined as the glass transition temperature. (5) Heat cycle test An iron spring washer having a diameter of 20 mm was placed in a petri dish having a diameter of 50 mm, and a sample was further placed so as to incorporate the washer.
And then left at room temperature to remove the cured product from the petri dish to prepare a test piece. This test piece was repeatedly subjected to one cycle of treatment of holding at -30 ° C. for 1 hour and then at 120 ° C. for 1 hour. X. (6) Shear adhesive strength 100 mm x 25 mm based on JIS K 6850
A 1.6 mm SPCC-SD steel plate is polished with a # 150 polishing cloth, and then applied to a degreased one so as to have a single overlap of 12.5 mm, thermally cured at 120 ° C. for 3 hours, and room temperature. Under the condition of 25 ° C. and the crosshead moving speed of 5 mm / min.
The shear adhesive strength was measured and indicated by the average of the measured values of five samples. (7) T peel adhesion strength According to JIS K 6854, SPCC
-Using a degreased SD steel plate (150 mm x 25 mm x 0.5 mm), a sample was applied and cured at 120 ° C for 3 hours to prepare a test piece. This test piece 5
25 ° C, crosshead moving speed 50
The test was conducted under the condition of mm / min, the peel adhesion strength was measured, and the average value of the obtained measured values was shown.

[Procedure amendment 6]

[Document name to be amended] Statement

[Correction target item name] 0025

[Correction method] Change

[Correction contents]

Example 1, Comparative Examples 1 to 8 One-part epoxy resin-based adhesives having the compositions shown in Table 1 were prepared, and their performance was evaluated. Table 1 shows the results.

Continued on the front page F term (reference) 4J040 CA052 CA072 DA122 DF042 DF052 DF072 EC061 EC062 EC401 EC402 EK002 GA06 GA07 GA15 GA19 GA20 GA25 HC00 HC01 HC15 HC16 HC19 HC24 HD23 HD24 JA03 JA12 JB02 KA03 KA16 KA17 LA02 LA03

Claims (5)

[Claims] (1) 20 to 70% by weight of a liquid urethane-modified epoxy resin capable of forming a chelate; and (B) crosslinked rubber particles 6 to 20 having an average particle diameter of 0.05 to 0.5 μm.
% By weight and (C) liquid bisphenol type epoxy resin 1
One-component type obtained by blending (D) 2 to 20 parts by weight of a latent curing agent and (E) 0.1 to 20 parts by weight of a curing accelerator with respect to 100 parts by weight of a resin component consisting of 0 to 75% by weight. Epoxy resin adhesive. 2. The one-pack type epoxy resin adhesive according to claim 1, wherein the crosslinked rubber fine particles of the component (B) are fine particles comprising a crosslinked product of acrylonitrile-butadiene copolymer rubber. 3. The one-pack type epoxy resin adhesive according to claim 1, wherein the liquid bisphenol type epoxy resin as the component (C) is a liquid bisphenol F type epoxy resin. 4. The method according to claim 1, wherein the curing accelerator of the component (E) is at least one selected from toluenebisdimethylurea and methylenediphenylbisdimethylurea.
4. The one-pack type epoxy resin adhesive according to 2 or 3. 5. A crosslinked rubber fine particle of the component (B) and a liquid bisphenol type epoxy resin of the component (C) are contained in the component (C) in a state where the component (B) is dispersed to form a sea-island structure. The one-pack type epoxy resin-based adhesive according to any one of claims 1 to 4, wherein