JPH07216297A - Tough powder coating composition - Google Patents

Abstract

(57) [Abstract] [Purpose] Epoxy resin powder coating composition suitable as an insulating material for capacitors, which has excellent toughness in its cured film and also excellent in moisture resistance and flame retardancy. I will provide a. [Structure] (a) Bisphenol type epoxy resin having an epoxy equivalent of 500 to 2000, (b) organic bromine compound,
(C) a curing agent composed of a phenol novolac resin and a higher aliphatic dicarboxylic acid, (d) a curing accelerator composed of triphenylphosphine or a novolac resin salt of 1,8-diazabicyclo (5,4,0) undecene-7 And (e)
A tough powder coating composition comprising a filler composed of aluminum hydroxide and a flaky inorganic substance, and an insulating material for a capacitor comprising the composition.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a tough powder coating composition, which has toughness that does not break even when subjected to a safety functional test of a capacitor, and has good moisture resistance, flame retardancy and film. The present invention relates to an epoxy resin-based powder coating composition that gives a cured film having strength.

[0002]

2. Description of the Related Art Epoxy resin powder coating compositions (hereinafter referred to as
Because of its excellent insulating properties, ceramic capacitors, film capacitors,
Widely used as an insulating material for electric and electronic parts such as resistor networks. Among such compositions, those used for capacitor insulation are such that the cured film is not destroyed by the gas pressure that may occur during charging / discharging under overvoltage. It is required to have strong strength. A composition containing an internally plasticized epoxy resin is known as a composition that meets such a demand (Japanese Patent Laid-Open No. 5-2794).
No. 52). However, this is still unsatisfactory in terms of moisture resistance and flame retardancy, and leaves room for improvement.

[0003]

DISCLOSURE OF THE INVENTION The present invention provides an epoxy resin-based powder suitable as an insulating material for capacitors, which has excellent toughness in its cured film and excellent properties in terms of moisture resistance and flame retardancy. It is an object of the present invention to provide a body coating composition.

[0004]

The present inventors have completed the present invention as a result of intensive studies to solve the above problems. That is, according to the present invention, (a) a bisphenol type epoxy resin having an epoxy equivalent of 500 to 2000,
(B) Organic bromine compound, (c) Curing agent composed of phenol novolac resin and higher aliphatic dicarboxylic acid, (d)
It contains a curing accelerator consisting of a novolac resin salt of triphenylphosphine or 1,8-diazabicyclo (5,4,0) undecene-7 and (e) a filler consisting of aluminum hydroxide and a scale-like inorganic substance. A tough powder coating composition is provided. Further, according to the present invention, there is provided an insulating material for a capacitor, which comprises the above composition.

The present invention will be described in detail below. The epoxy resin used as the component (a) in the present invention has an epoxy equivalent of 500 to 2000, preferably 600 to 1200.
Bisphenol type epoxy resin is used. The epoxy resin is used alone or in the form of a mixture, and when used in the form of a mixture, its weight average epoxy equivalent is 500 to
It may be in the range of 2000. When the epoxy equivalent is less than 500, problems such as blocking of the powder coating and deterioration of the toughness of the cured coating occur. On the other hand, when it is more than 2000, melt flowability of the powder coating, poor finish of cured coating, and moisture resistance of cured coating. Problems such as deterioration of heat resistance and heat resistance occur.

As the organic bromine compound used as the component (b) in the present invention, various compounds having a flame retardant effect which have been generally used conventionally are used. As such a compound, for example, an aromatic bromide such as hexabromobenzene, decabromobiphenyl ether, tetrabromobisphenol, decabromobiphenylalkane, and brominated phenol can be used, but a brominated epoxy resin is used. Is preferred. Examples of the brominated epoxy resin include brominated bisphenol A type epoxy resin, brominated phenol novolac type epoxy resin, and brominated cresol novolac type epoxy resin. The blending amount of such an organic bromine compound is as follows: (a) component, (b)
The content as bromine is 5 to 30% by weight, preferably 7 to 25, based on the total amount of the components, the components (c) and (d).
% By weight. If the blending amount of the organic bromine compound is less than the above range, a sufficient flame retarding effect cannot be obtained. On the other hand, if the blending amount is more than the above range, physical properties of the cured film obtained from the composition are impaired.

The curing agent used as the component (c) in the present invention comprises a phenol novolac resin and a higher aliphatic dicarboxylic acid. As the novolac resin, an alkylphenol novolac resin such as a cresol novolac resin can be used in addition to a known phenol novolac resin. On the other hand, as the higher aliphatic dicarboxylic acid, those represented by the following general formula are used. HOOC-R-COOH (1) In the above formula, R is a saturated or unsaturated higher aliphatic group (alkyl group, alkenyl, etc.), preferably a linear higher aliphatic group, having 8 or more carbon atoms. , Preferably 14-22
Is. The compounding amount of the total curing agent is 10 to 50 parts by weight, preferably 1 to 100 parts by weight of the epoxy resin (when the brominated epoxy resin is used as the organic bromine compound, the brominated epoxy resin is used as an epoxy resin component).
5 to 30 parts by weight. The proportion of phenol novolac resin in the total curing agent is 25 to 75% by weight, preferably 3%.
0 to 70% by weight, and the proportion of higher aliphatic dicarboxylic acid is 25 to 75% by weight, preferably 30 to 70% by weight. If the total amount of the curing agent is less than the above range, a cured film having sufficient toughness cannot be obtained. On the other hand, if it exceeds the above range, the storage stability of the powder coating is reduced and the moisture resistance of the cured film is reduced. Etc. causes problems. Further, even if the ratio of the higher aliphatic dicarboxylic acid to the total curing agent is out of the above range, a cured film having sufficient toughness cannot be obtained.

The curing accelerator used as the component (d) in the present invention is a novolac resin salt of triphenylphosphine or 1,8-diazabicyclo (5,4,0) undecene-7 (hereinafter abbreviated as DBU). is there. The DBU novolak resin salts include phenol novolac resin salts as well as alkylphenol novolac resin salts such as cresol novolac resin salts. The blending amount is generally 0.5 to 7 parts by weight with respect to 100 parts by weight of the epoxy resin,
The proportion is preferably 1 to 4 parts by weight. In the case of triphenylphosphine, the proportion is preferably 1 to 3 parts by weight, while in the case of the DBU novolac resin salt, the proportion is preferably 1 to 4 parts by weight. When the compounding amount of the curing accelerator is less than the above range, the curing rate of the composition is slow, while when it exceeds the above range, there arises a problem that the melt fluidity of the powder coating material, the storage stability, etc. are deteriorated. .

The filler used as the component (e) in the present invention is aluminum hydroxide and a scale-like inorganic substance. Examples of the scale-like inorganic substance include talc, mica, kaolin, glass flakes and the like. The average particle size of aluminum hydroxide is 0.1 to 30 μm, preferably 5 to 20 μm, and the average particle size of the scale-like inorganic substance is 0.1 to 40 μm, preferably 1 to 20 μm. The compounding amount of all the fillers is 20 to 100 parts by weight, preferably 30 to 80 parts by weight, per 100 parts by weight of the epoxy resin. Further, the proportion of the scale-like inorganic substance in the total filler is 28 to 82% by weight, preferably 30 to 80% by weight. If the blending amount of the filler is less than the above range, not only sufficient mechanical strength cannot be obtained in the obtained cured film, but also its flame retardancy, water absorption and the like become insufficient. On the other hand, if the blending amount exceeds the above range, the obtained cured film becomes brittle and its toughness is impaired. Among the filler components of the present invention,
The scale-like inorganic substance is important, and if it is not used, the flame retardancy of the cured film will be insufficient, and in the combustion test, it will cause the drop of molten droplets and the moisture resistance is also unsatisfactory. Becomes

In the composition of the present invention, in addition to the above-mentioned components, conventional auxiliary components, for example, flame retardant aids such as antimony oxide, leveling agents such as acrylic acid ester oligomers,
An appropriate amount of a modifier such as polyvinyl butyral, a laser marking agent, various colorants and the like can be added. The composition of the present invention may be prepared by mixing the blended components with a mixer or the like, followed by melt-mixing with a kneader or the like, cooling and solidifying the resulting mixture, and pulverizing the composition according to a conventional method.
The composition of the present invention is applied to the surface of a material to be treated by various conventionally known coating methods such as a fluidized-bed immersion method, an electrostatic fluidization tank method, an electrostatic spray method, a sprinkling method, a rolling method, a spray method, and a thermal spraying method. The surface of the material to be treated can be
A cured film is formed from the composition of the present invention. The curing conditions for the composition of the present invention are: temperature: 90 to 180 ° C., preferably 100 to 130 ° C., time: 30 to 120 minutes, preferably 40 to 100 minutes.

[0011]

EXAMPLES Next, the present invention will be described in more detail by way of examples. In the following, all parts and% are based on weight.

Examples 1 to 5 and Comparative Examples 1 to 4 Powder coatings having the component compositions (parts by weight) shown in Tables 1 and 2 were prepared, their performances were evaluated, and the results are shown in the respective tables. The blending components shown in Tables 1 and 2 have the following contents.

Epicoat 1001: Bisphenol A type epoxy resin (w
pE (epoxy equivalent) 475, mp 69 ° C. (Okaka Shell Epoxy Co., Ltd.) 1002: Bisphenol A type epoxy resin (wpE (epoxy equivalent) 650, mp 83 ° C.) (Okaka Shell Epoxy Co., Ltd.) 1004: bisphenol A type epoxy resin (wpE (epoxy equivalent) 925, mp 99 ° C) (Oilized Shell Epoxy Co.) 1007: Bisphenol A type epoxy resin (wpE (epoxy equivalent) 1925, m.p 127 ° C) (oiled shell EROX 745: Brominated epoxy resin (bis A type)
(wpE 400, mp 70 ° C, bromine content 48%) (Asahi Kasei Corporation) SL-20: HOOC (CH ₂ ) _18- COOH higher aliphatic dicarboxylic acid as a main component (acid equivalent 170, mp 120 ° C) (Okamura Oil Co., Ltd.) Tamanor 759: phenol novolac resin (phenol equivalent 104, mp 99 ° C.) (Arakawa Chemical Industry Co., Ltd.) EK-171: Bisphenol A compound (Okaka Shell Epoxy Co., Ltd.) PP-360: triphenylphos Fin (TP
P) (mp 80 ° C) (Kai Kaseisha) DBU salt: 1,8-diazabicyclo (5,4,0) undecene-7 phenol novolac resin salt (U-cat SA- 83)
1) (San Apro Co., Ltd.) Crystallite A-A: Crushable crystalline silica (average particle size 6μ
m) (Tatsumorisha) Highlite H-32: Aluminum hydroxide (average particle size 8
μm) (Showa Denko KK) H-42: Aluminum hydroxide (average particle size 1 μm) (Showa Denko KK) Talc JA-68R: Talc (average particle size 7 μm) (Asada Flour Milling Co.) SW-C: Talc (average particle size) Diameter 7 μm) (Asada Milling Co., Ltd.) Mica C-1000: Mica (Average particle size 10 μm) (Shiraishi Industry Co., Ltd.) Burgess 30: Kaolin clay (Average particle size 1.5 μm)
(Shiraishi Industry Co., Ltd.) Viroguard AN-900: Antimony trioxide (Sb ₂ O ₃ 99.5% or more) (Daiichi Kogyo Seiyaku Co., Ltd.)

The above-mentioned EK-171 (bisphenol A compound) is a reaction product of a bisphenol A type epoxy resin and bisphenol A, and is represented by the following general formula, the main components of which are n = 0 and n = It is composed of two compounds.

[Chemical 1]

The test methods and conditions for the performance of the cured products shown in Tables 1 and 2 are as follows. (1) Hardened product strength test (tensile fracture test) (Test piece) Manufacturing method: A plate is formed by heating and pressing. (110 ° C
(Curing in 90 minutes) Specimen size: 150 × 10 × 0.5 mm (Test equipment) Tensilon universal tensile test (Test conditions) Crosshead speed 10 mm / min At 90 ° C, pull the specimen until it breaks. Measures the breaking energy (kgf-mm) of. The tensile breaking energy of 60 kgf-mm or more is sufficient. (2) Combustion test (based on UL94) (Test piece) Manufacturing method: plate-shaped by heating and pressing. (110 ° C x
Curing in 90 minutes) Specimen size: 127 × 12.7 × 0.5 mm The flammability must be UL94 V-0. (3) Absorption rate (test piece) Manufacturing method: plate-shaped by heating and pressing. (110 ° C x
Curing in 90 minutes) Specimen size: 50 x 50 x 0.5 mm (Test condition) Place in water boiled at 100 ° C for a specified time. (Evaluation method) Take out from water at 1, 5 and 20 hours and calculate the difference from the initial weight (% display). As the water absorption rate, it is sufficient if the value at 20 hours is 2.0% or less.

[0016]

[Table 1]

[0017]

[Table 2] *: The strength at 90 ° C is too small to measure. Example 6 The same as in Example 1 except that the weight ratio of the long-chain dicarboxylic acid (SL-20) and the phenol novolac resin (Tamanol 759) was changed. An experiment was conducted. The results are shown in Table 3.

[0018]

[Table 3]

Example 7 An experiment was conducted in the same manner as in Example 1 except that the weight ratio of aluminum hydroxide and talc was changed. The results are shown in Table 4.

[0020]

[Table 4]

[0021]

EFFECT OF THE INVENTION The tough powder coating composition of the present invention has excellent toughness in the cured film, and also has excellent moisture resistance and flame retardancy, and is suitable as an insulating material for capacitors. It is a thing. In the case of a capacitor with an insulating coating on the surface, gas may be generated from the capacitor during charging / discharging under overvoltage, but the gas pressure at that time is applied to the insulating coating formed on the surface of the capacitor. . In this case, when the insulating coating film is inferior in toughness, the insulating coating film is broken (or cracked) due to the gas pressure. The cured film formed from the composition of the present invention has excellent toughness, and thus does not cause such destruction of the insulating coating film. Further, the capacitor insulating coating film is required not to cause combustion due to overheating of the capacitor, etc., but the cured film obtained from the composition of the present invention has excellent flame retardancy, and such a requirement is satisfied. I am satisfied. Further, the capacitor insulating coating film is required to have its insulating property not deteriorated by moisture, but the cured film obtained from the composition of the present invention has excellent moisture resistance and satisfies such a requirement. It is a thing. The composition of the present invention is advantageously used not only as an insulating material for capacitors, but also as an insulating material for electronic / electrical parts such as hybrid IC, varistor, and thermistor.

Claims (4)

[Claims] 1. A bisphenol type epoxy resin having an epoxy equivalent of 500 to 2000, (b) an organic bromine compound, (c) a curing agent comprising a phenol novolac resin and a higher aliphatic dicarboxylic acid, (d) triphenylphosphine or A curing accelerator comprising a novolac resin salt of 1,8-diazabicyclo (5,4,0) undecene-7, and (e) a filler comprising aluminum hydroxide and a scale-like inorganic substance. A tough powder coating composition. 2. The content of the total curing agent is 10 to 50 parts by weight with respect to 100 parts by weight of the epoxy resin, and the ratio of the higher aliphatic dicarboxylic acid to the total curing agent is 25 to 75% by weight. The composition of 1. 3. The content of the total filler is 20 to 100 parts by weight with respect to 100 parts by weight of the epoxy resin, and the ratio of the scale-like inorganic substance to the total filler is 28 to 82% by weight. Or the composition of 2. 4. An insulating material for capacitors, comprising the composition according to claim 1.