JPH09278987A - Epoxy resin composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an epoxy resin composition capable of giving a covering excellent in thermal shock resistance and moisture resistance, and useful for a powder coating material, etc., as an insulating covering material for an electric.electronic part material by using the composition containing a specific thermal shock resistance improver. SOLUTION: This epoxy resin composition contains (A) an epoxy resin, (B) a hardener such as an acid anhydride, a polyamine or a novolak-type phenolic resin, (C) a filler such as an inorganic filler having <=20μm average particle diameter and (D) an acrylic resin as a polymer of an acrylate monomer and having a functional group such as an epoxy, a carboxyl or OH as a thermal shock resistance improver. Preferably, the composition contains 1-20wt.% of the component D based on whole of the composition.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an epoxy resin composition which is excellent in thermal shock resistance and moisture resistance and is suitable for insulating coating of electric / electronic parts.

[0002]

2. Description of the Related Art Epoxy resins have hitherto been used in a wide variety of fields such as electric / electronics, paints and adhesives because of their excellent reactivity, workability and cured product characteristics. Usually, epoxy resin is cured in a heated state and then cooled to be used for an end use. When used as an insulating coating for electric / electronic components, internal stress is generated due to the difference between the linear expansion coefficient of the epoxy resin and that of the element to be coated, and peeling or breakage easily occurs when a thermal shock is applied.

As a method of reducing the internal stress, generally, there is a method of selecting an optimum resin or curing agent, a method of adding CTBN or the like as a modifier. However, the former lowers the glass transition temperature (Tg) by introducing a flexible chemical structure, and the latter lowers the flowability and curability.
In addition, the adhesion is insufficient from the viewpoint of compatibility between the resin and the modifier,
There is a problem such as a decrease in moisture resistance. Further, a method for improving thermal shock resistance by adding a styrene-based thermoplastic elastomer (Japanese Patent Laid-Open No. 6-93171).
However, in recent years, higher thermal shock resistance is often required, and it is still insufficient in such a field.

[0004]

DISCLOSURE OF INVENTION Problems to be Solved by the Invention In the present invention, as a result of research on a material suitable for a powder coating having an excellent thermal shock resistance without deteriorating the electrical characteristics and other characteristics, a polymer of an acrylic acid ester monomer is obtained. In addition, by including an acrylic resin having a functional group in the polymer,
An object of the present invention is to provide an epoxy resin composition which gives a cured product having excellent thermal shock resistance and moisture resistance as characteristics of electronic parts.

[0005]

The present invention relates to an epoxy resin composition comprising an epoxy resin, a curing agent and a filler as essential components, which is a polymer of acrylic acid ester monomer and has a functional group in the polymer. An epoxy resin composition comprising a resin as a thermal shock improver.

The acrylic resin used as the thermal shock improver in the present invention has a functional group such as an epoxy group, a carboxyl group and a hydroxyl group in its molecule, has a high compatibility with the epoxy resin, and has a high dispersibility. It is considered that it is excellent in shear strength and peeling strength due to its good hardness. Further, since a high elongation is obtained, the elastic modulus is lowered and the stress is relaxed. As a result, it is considered that since the strength is higher than the internal stress generated by the thermal shock, peeling or breakage does not occur, and water does not easily enter, so that the moisture resistance is improved.

Acrylic resins having a functional group, which are polymers of acrylic acid ester monomers, include Paraloid EXL-2314 and Paraloid EXL manufactured by Kureha Chemical Industry Co., Ltd.
-3386 etc. are mentioned. The amount of the acrylic resin compounded is preferably 1 to 20 parts by weight with respect to 100 parts by weight of the epoxy resin. If the blending amount is less than 1 part by weight, the effect on the thermal shock resistance becomes small, and if it exceeds 20 parts by weight, the viscosity becomes high and the flowability deteriorates.

Examples of the epoxy resin used as a raw material in the present invention include bisphenol A type epoxy resin,
Diglycidyl ether type epoxy resin such as bisphenol F type epoxy resin, novolac type epoxy resin such as phenol novolac type epoxy resin, cresol novolac type epoxy resin, glycidyl ester type epoxy resin, glycidyl amine type epoxy resin, linear aliphatic type epoxy resin Examples of the resin include, but are not limited to, a resin, an epoxy resin to be encapsulated, and a halogenated epoxy resin.

The curing agent and curing accelerator used in the present invention include acid anhydrides, polyamines, novolac type phenolic resins, tertiary amines, imidazole compounds and the like.
Select and use more than one seed. Further, a filler is used if necessary. As the filler, an inorganic filler having an average particle size of 20 μm or less is usually used. For example, zircon powder, talc powder, crystalline silica powder, fused silica powder, calcium carbonate powder, magnesia powder, calcium silicate powder, hydrated alumina powder. , Alumina powder and the like. In the present invention, additives such as pigments, coupling agents, leveling agents and the like can be added if necessary.

The epoxy resin composition of the present invention may be in a liquid state such as a casting material, a powder state such as a powder coating material, a granular state such as a molding material or a lump state, but a typical use is a powder state. Examples include paints.

As a method for producing the epoxy resin composition of the present invention, for example, in the case of powder coating, the raw material components weighed in a predetermined ratio are thoroughly mixed with a mixer, and then the mixture is extruded, cokneadered or rolled. There is a method of melt-mixing and then pulverizing with a pulverizer. As a method for performing insulation coating of electric / electronic parts with the powder coating obtained by the above method, a fluidized dipping method, an electrostatic fluidized dipping method, a rolling method, a sprinkling method, a hot spray method,
A general powder coating method such as an electrostatic spray method is used.

Also, in the case of casting materials and molding materials, they can be manufactured by known techniques and can be used as insulating materials.

[0013]

Next, the present invention will be described in more detail with reference to examples.

Example 1 Bisphenol A type epoxy resin (epoxy equivalent 950) 50 parts by weight Polymer of acrylic acid ester monomer, acrylic resin having functional group in polymer (EXL-2314) 5 fused silica powder (average) Particle size 15 μm) 50 Trimellitic anhydride 4 Triphenylphosphine 0.1 The above composition is blended, mixed with a Henschel mixer, melt-kneaded with a cokneader, and then ground with a grinder to give an average particle size of 40. A powder coating consisting of an epoxy resin composition of -60 μm was obtained.

Example 2 Bisphenol A type epoxy resin (epoxy equivalent 950) 50 parts by weight Acrylic resin (EXL-2314), which is a polymer of acrylic acid ester monomer and has a functional group in the polymer, 20 fused silica powder ( Average particle size 15 μm) 50 trimellitic anhydride 4 triphenylphosphine 0.1 The above composition is blended, mixed with a Henschel mixer, melt-kneaded with a cokneader, and then crushed with a crusher to obtain an average particle size. A powder coating material having an epoxy resin composition of 40 to 60 μm was obtained.

Comparative Example 1 A powder coating composition made of an epoxy resin composition having an average particle size of 40 to 60 μm in the same manner as in Example 1 except that the acrylic ester monomer and the acrylic resin having a functional group were not blended. Got

Comparative Example 2 In Example 1, a styrene thermoplastic elastomer (Tuftec H-1031 manufactured by Asahi Kasei Co., Ltd.) was used instead of the acrylic ester monomer and the acrylic resin having a functional group.
In the same manner as above, but with an average particle size of 40 to 60 μm.
A powder coating material comprising the above epoxy resin composition was obtained.

Comparative Example 2 A powder made of an epoxy resin composition having an average particle size of 40 to 60 μm was prepared in the same manner as in Example 2, except that 40 parts by weight of an acrylic acid ester monomer and an acrylic resin having a functional group were mixed. Got body paint.

Table 1 shows the powder properties of the resin compositions of Examples 1 and 2 and Comparative Examples 1 to 3 and the properties and parts properties of the cured products obtained by curing at 150 ° C. for 1 hour.

[Table 1]

(Measurement method) 1. Flow rate: The rate of increase in diameter when a test piece of 10φ × 7 mm (tablet of powder coating) was left for 30 minutes in a dryer at a predetermined temperature. The flow rate is calculated by the following formula. Flow rate (%) = [{average diameter after treatment (mm) -10 (mm)} /
10 (mm)] × 100 2. Gelation time: This is the time required for putting a certain amount of powder coating material on a hot plate having a predetermined temperature and kneading with a predetermined spatula for gelation (state in which the yarn is not pulled). 3. Boiled water absorption: Test piece of cured powder coating (50 x 50
X 2 mm) is the percentage of the increased mass after immersion in boiling water for 2 hours and the mass of the test piece before immersion. Boiled water absorption rate (%) = {(W2-W1) / W1} × 100 W1: mass of test piece before boiling W2: mass of test piece after boiling 4. Moisture resistance: Powder coating is applied to electronic parts (varistor), cured at 150 ° C for 1 hour, then left in a pressure cooker tester and the voltage when a constant current is applied at regular intervals is set. It measures and evaluates by the change rate. The numerical value in the table is the processing time at which the voltage change rate is 5% or more. 5. Thermal shock resistance: Powder coating is applied to electronic parts (varistor), cured at 150 ° C for 1 hour, and then left in a heat cycle tester set to predetermined conditions to prevent cracking of the coated object. It is to see how well it enters. The numerical value in the table is the number of cycles in which the coated article cracked.

[0021]

EFFECT OF THE INVENTION When an epoxy resin composition which is a polymer of an acrylic acid ester monomer of the present invention and contains an acrylic resin having a functional group is used as an insulating coating material, electrical properties and other properties are deteriorated. It is possible to give a coating with excellent thermal shock resistance and moisture resistance without any problem.

Claims (4)

[Claims] 1. An epoxy resin composition comprising an epoxy resin, a curing agent and a filler as essential components, wherein an acrylic resin which is a polymer of an acrylic acid ester monomer and has a functional group in the polymer is used as a heat shock improver. An epoxy resin composition comprising: 2. The epoxy resin composition according to claim 1, which is a polymer of an acrylic acid ester monomer, and the functional group in the acrylic resin having a functional group in the polymer is an epoxy group, a carboxyl group or a hydroxyl group. . 3. A polymer of an acrylic acid ester monomer, wherein 1 to 20 parts by weight of an acrylic resin having a functional group in the polymer is contained in the entire composition. Epoxy resin composition. 4. A powder coating comprising the epoxy resin composition according to claim 1.