JPH0517720A - Incombustible coating paint for electronic part, its production and electronic part coated with incombustible paint - Google Patents

Abstract

PURPOSE:To provide an incombustible coating paint for electronic part, curable by baking at a relatively low temperature within a short time, having excellent storage stability and giving an odorless cured coating film resistant to ignition even by the heat generation in itself under over-loaded condition or in contact with external flame. CONSTITUTION:The objective paint can be produced by compounding (A) 100 pts.wt. of a binder component composed of a thermosetting silicone resin obtained by the co-hydrolytic condensation of (A1) 10-80 pts.wt. of a silane of formula I (X is OH or hydrolyzable group) and (A2) 20-90 pts.wt. of an alkylsilane expressed by formula II (R is 1-3C alkyl; Y is OH, hydrolyzable group, etc.) and (B) 400-900 pts.wt. of an inorganic pigment (e.g. mica powder and tale).

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to non-combustible electronic parts used in electronic parts accompanied by overload or self-heating, that is, resistors, thermistors, varistors, transistors, film capacitors, ceramic capacitors, coils, various heaters and the like. The present invention relates to a coating paint, a method for producing the coating paint, and an electronic component coated with the nonflammable coating paint.

[0002]

TECHNICAL BACKGROUND OF THE INVENTION AND PROBLEMS The general coating materials for electronic parts are mainly organic, epoxy-based, phenol-based,
Urethanes, polybutadienes, and silicones having excellent flame retardancy are known and put to practical use. However, the conventional coating material has a drawback that the curing and baking time is long. Silicone-based products, in particular, have to be baked at high temperatures, lack mass productivity in the manufacturing process of electronic parts, and although there are many demands for improvement from the viewpoint of energy saving, they are often used because of their excellent flame retardancy. Is the current situation.
However, recently, development of a smoke-free electronic component coated with a non-combustible paint that cures quickly has been desired from the viewpoint of safety in electronic component manufacturing process or use. For example, as a prior example, compositions of this type are described in JP-A-59-155468, JP-A-60-148004, and JP-A-62-256876. However, both have aqueous colloidal silica or aqueous alumina colloid as a component,
Although the curing was fast, the water derived from these remained in the coating composition, resulting in poor storage stability and problems in use. The cured coating was brittle, and the moisture resistance and solvent resistance were insufficient. .

[0003]

SUMMARY OF THE INVENTION The present invention solves these problems,
Allows baking and curing at a relatively low temperature (about 120 ° C) for a short time (about 10 minutes), excellent storage stability of the paint, and the cured coating has no odor and self-heating when electronic components are overloaded. It does not ignite even when exposed to external flames, and has quality characteristics such as moisture resistance, solvent resistance, and coating strength that are equal to or better than those of conventional products, and prevent abnormal overload and It is an object of the present invention to provide a nonflammable coating paint suitable as a coating material for electronic parts, which is highly safe even when self-heating occurs, a method for producing the same, and an electronic part coated with the nonflammable coating paint.

[0004]

The present inventors have conducted extensive studies in order to achieve the above object, and as a result, SiX ₄ and RSiY ₃ (where,
X and Y are a hydroxyl group or a hydrolyzable group, R is a carbon number of 1 to 3.
Of the silane, which is represented by the formula (1), is added to the co-hydrolyzed condensate of a specific ratio of the silane, and the inorganic pigment of a specific ratio is blended to provide excellent heat resistance, moisture resistance, solvent resistance and coating strength. The inventors have found that a non-flammable coating composition for electronic parts can be obtained, and completed the present invention. Furthermore, it was found that the storage stability of the paint is improved by having a step of removing water after co-hydrolyzing and condensing silane in the presence of water when preparing the coating paint of the present invention. The present invention has been accomplished. That is, the non-combustible coating material for electronic parts of the present invention comprises (1) 10 to 80 parts by weight of a silane represented by the general formula: SiX ₄ ... (I) (wherein, X represents a hydroxyl group or a hydrolyzable group). General formula: RSiY ₃ (II) (wherein R represents an alkyl group having 1 to 3 carbon atoms, Y represents a hydroxyl group or a hydrolyzable group) and 20 to 90 parts by weight of an alkylsilane is co-hydrolyzed. It is characterized by comprising 100 parts by weight of a binder component composed of a thermosetting silicone resin obtained by condensation and (2) 400 to 9,000 parts by weight of an inorganic pigment. Further, the manufacturing method of the present invention,
When the silanes of the formulas (I) and (II) are cohydrolyzed and condensed in the presence of water to prepare a binder component, and an inorganic pigment is further compounded to prepare the above coating composition, the silane cohydrolysis is used. The method is characterized by having a step of removing water after the decomposition and condensation.

In the present invention, the formulas: SiX ₄ (I) and RS
The co-hydrolyzed condensate of silane represented by iY ₃ (II) is a compound serving as a base of a thermosetting silicone resin serving as a binder component. In the above, R represents an alkyl group having 1 to 3 carbon atoms. Specific examples of the alkyl group having 1 to 3 carbon atoms include methyl group, ethyl group, n-propyl group and isopropyl group. In order to maximize the low smoke generation of electronic parts when they generate heat, it is desirable that R 1 is a methyl group. X and Y each represent a hydroxyl group or a hydrolyzable group, and examples of the hydrolyzable group include methoxyl group, ethoxyl group, propoxyl group, isopropoxyl group, butoxyl group and other alkoxyl groups; propenoxy group and other alkenyloxy groups. Acyloxy groups such as acetoxy group and benzoxy group; Organoxime groups such as acetone oxime group and butanone oxime group; Organoaminoxy groups such as dimethylaminoxy group and diethylaminoxy group; Dimethylamino group, diethylamino group, cyclohexylamino group, etc. An organoamino group; and an organoamide group such as an N-methylacetamide group and a halogen atom such as a chlorine atom. Among these, a chlorine atom and an alkoxyl group are preferable from the viewpoint of the reaction rate of hydrolysis and the ease of handling, and an alkoxyl group that is easy to control the hydrolysis reaction is more preferable. Particularly, a methoxyl group and an ethoxyl group are preferable.

The thermosetting silicone resin used in the nonflammable coating composition of the present invention serves as a binder component. This thermosetting silicone resin is obtained by cohydrolytic condensation of 10 to 80 parts by weight of silane (I) and 20 to 90 parts by weight of alkylsilane (II). When the blending amount of silane (I) is less than 10 parts by weight, the content of organic groups is large, and the amount of smoke generated when the electronic component generates heat is large. If the proportion of the hinder component in the coating composition is reduced in order to avoid this problem, there arises a problem that the coating film strength decreases. Further, when the blending ratio of silane (I) exceeds 80 parts by weight, the curability of the binder component is greatly increased, the storage stability of the coating composition is deteriorated, the toughness of the cured coating is lost, and when the electronic component is coated, The coating film is likely to crack. The thermosetting silicone resin of the present invention can be synthesized by a commonly known method of cohydrolysis condensation of silane. For example, the hydrolyzable groups X and Y
When is a chlorine atom, it can be synthesized by mixing chlorosilane (I) and alkylchlorosilane (II), dropping them in water and mixing and stirring. In the case of hydrolysis of alkoxysilanes, a hydrolysis catalyst can be used if desired. Acids or bases can be used as catalysts. Suitable acid catalysts include acetic acid, chloroacetic acid, citric acid, benzoic acid, formic acid, propionic acid, maleic acid,
Both organic acids such as oxalic acid and glycolic acid and inorganic acids such as hydrochloric acid are included.

In order to improve the storage stability of the coating composition of the present invention, it has a step of removing excess water in the reaction system after the cohydrolysis reaction of silane (I) and alkylsilane (II). It is preferable. For example, an azeotropic alcohol such as methanol, ethanol, isopropanol, n-propanol, isobutanol, or n-butanol is added after the azeotropic hydrolysis reaction, and excess water in the hydrolysis reaction system is obtained by azeotropic distillation of water-alcohol. The water and other low fractions are distilled off to prepare a thermosetting silicone resin solution. The amount of water in the thermosetting silicone resin solution is
It is preferably 10% or less, particularly preferably 1% or less. Prepare a coating using a binder component consisting of a thermosetting silicone resin solution containing less water,
By reducing the water content in the coating composition, it is possible to produce a nonflammable coating composition for electronic parts, which has excellent storage stability. The water content in the paint is preferably 2% or less, particularly preferably 1% or less.

The inorganic pigments used in the coating composition of the present invention include extender pigments and coloring pigments. Examples of the pigment include mica powder, talc, silica, clay, kaolin, barite, titanium oxide, aluminum hydroxide, aluminum oxide, zinc oxide, lithopone, zinc sulfide, iron oxide, zirconium oxide, cadmium red, carbon black, graphite, Manganese dioxide, ceramic black, chromium oxide, cobalt green, gine green, cadmium yellow, titanium yellow pigment, cobalt blue, konjou, phthalocyanine blue, aluminum powder, etc., and those surface-treated with a silane coupling agent, etc. Can be mentioned.

The blending amount of this inorganic pigment is 400 to 9,000 parts by weight with respect to 100 parts by weight of the thermosetting silicone resin (1). If it is less than 400 parts by weight, sufficient low smoke generation and low-temperature curing property cannot be obtained, and if it exceeds 9000 parts by weight, the strength of the coating film decreases, and the moisture resistance of the coating film is relatively high even though a relatively expensive pigment is used. However, further improvement in solvent resistance cannot be expected, which is not preferable.

The coating composition of the present invention is used by dissolving it in a solvent depending on the convenience of preparation of the coating composition or coating workability.
As the solvent, alcohols such as methanol, ethanol, n-propanol, isopropanol, n-butanol, and isobutanol, propylene glycol monomethyl ether, dipropylene glycol monomethyl ether, tripropylene glycol monomethyl ether, propylene glycol monoethyl ether, 3- Methyl-
3-methoxybutanol, propylene glycol methyl ether acetate, 3-methyl-3-methoxybutyl acetate, ethylene glycol ethyl ether, ethylene glycol methyl ether, ethylene glycol butyl ether, diethylene glycol ethyl ether,
Examples thereof include glycols such as diethylene glycol butyl ether and aromatic solvents such as toluene and xylene. Further, the coating composition of the present invention may contain a fluidization regulator and a wetting agent.

As a method for producing the coating composition, the thermosetting silicone resin as the component (1), the inorganic pigment as the component (2) and, if necessary, other solvents and additives may be dispersed and mixed by a general production method, For example, three rolls and various dispersion mixing devices can be used. Further, the non-combustible coating composition for electronic parts in the present invention is applied to electronic parts by spray coating, dip coating, roller coating or casting method, and after volatilizing the solvent as required, baking temperature 80-250. By carrying out a curing treatment at a temperature of 1 ° C. for 1 to 100 minutes for dehydration condensation curing, an electronic component coated with a dense coating film composed of a binder component consisting of a ceramic siloxane and an inorganic pigment is provided. Electronic components coated with a non-combustible coating composition for electronic components of the present invention are excellent in moisture resistance, solvent resistance, even when the electronic components themselves become hot enough to cause red heat due to excessive current flowing, It has the features that it is extremely unlikely that smoke or cracks will occur in the coating film, and that the strength of the coating film will not decrease significantly.

[0012]

EFFECTS OF THE INVENTION When a nonflammable coating composition for electronic parts of the present invention is used to coat an electronic part, the coating film has good strength and adheres well to the electronic part, and has excellent moisture resistance and solvent resistance. Since the coated electronic component does not ignite or emit smoke even when it is overheated during overload and has excellent heat resistance, the safety as a coating material for the electronic component can be sufficiently maintained. In addition, since the coating composition has less water, the storage stability of the coating itself is excellent, and since it can be baked and cured at low temperature in a short time, it is excellent in mass productivity and is very useful from the viewpoint of energy saving.

[0013]

EXAMPLES The present invention will be specifically described below with reference to examples. In the examples, “part” means “part by weight” and “%” means “% by weight”.

Example 1 225 parts of tetraethoxysilane (TSL8124, manufactured by Toshiba Silicone Co., Ltd.), methyltriethoxysilane (TSL812)
3. To a solution consisting of 93 parts of Toshiba Silicone Co., Ltd. and 1 part of acetic anhydride, 106 parts of water was added to carry out the hydrolysis reaction.
Done at ~ 50 ° C for 24 hours. Then, 106 parts of isobutanol as an azeotropic alcohol were added, and the temperature was 20 to 50 ° C and 20 to 150 ° C.
Water-alcohol azeotropic distillation was performed under reduced pressure of mmHg to distill off excess water in the reaction system. Thus, 200 parts of a reaction liquid having a solid content of 50% was obtained. The water content in this reaction solution was 4%. To this reaction solution was added 133 parts of an equal mixed solvent of isopropanol and isobutanol to dilute,
A reaction solution was prepared so as to have a solid content of 30% to obtain a binder solution. Silica powder with an average particle size of 5μ
A paint was prepared by mixing and stirring 1000 parts. The water content in the paint was 0.6%. The paint obtained has a diameter of 5.0 mm and a length of 1
It was applied to a 5.0 mm fixed resistor and cured at 120 ° C. for 10 minutes. The performance test of this coating film and the nonflammability test at the time of overload were conducted by the following methods. The results were all good as shown in Table 1. The performance test method and the water content measuring method are shown below. Appearance of coating film : The presence or absence of cracks, color tone and gloss change were visually observed. Coating strength : The iron jig shown in FIG. 1 was pressed against the coating portion of the resistor, and the load when the coating peeled was measured. Solvent resistance : The coating film strength after ultrasonic cleaning with trichlene for 5 minutes was measured by the method described above. Boiling test : The coating film strength after being immersed in boiling water for 48 hours and dried at room temperature was measured by the same method as above. Non-flammability test : Apply a voltage 10 times higher than the rated voltage to the above-mentioned fixed resistor, apply an overload, and heat to observe the presence or absence of smoke from the coating and the duration of smoke generation, and then change the color of the coating. And the presence or absence of cracks was observed. Storage stability test : The coating composition was filled in a hard glass bottle and heated at 50 ° C, and the number of days until the resin component in the coating composition gelled was measured. Moisture content measurement : Moisture content was measured with a Karl Fischer moisture meter. As the dehydrating solvent, dehydrating solvent MS (trade name, manufactured by Mitsubishi Kasei Co., Ltd.) was used.

Example 2 Hydrolysis was carried out in the same manner as in Example 1 except that 162 parts of tetraethoxysilane, 140 parts of methyltriethoxysilane, 99 parts of water and 99 parts of isobutanol as an azeotropic alcohol were used. And azeotropic distillation to obtain a reaction liquid with a solid content of 50%.
I got 200 copies. The water content in the reaction solution was 3.5%. To this, 133 parts of propylene glycol monomethyl ether was added to prepare a binder solution so that the solid content was 30%. 1000 parts of the silica powder of Example 1 was mixed and stirred with this to prepare a coating material. The water content in the paint was 0.6%. The obtained coating material was evaluated in the same manner as in Example 1. The results are shown in Table 1.

Example 3 A coating material was prepared in the same manner as in Example 2 except that 108 parts of tetraethoxysilane, 183 parts of methyltriethoxysilane, 93 parts of water and 93 parts of isobutanol as an azeotropic alcohol were used. Was prepared. The obtained coating material was evaluated in the same manner as in Example 1. The results are shown in Table 1. By the way, the water content in the reaction solution and the paint was 4% and 0.7%. Example 4 Example 2 except that 79 parts of tetraethoxysilane, 205 parts of methyltriethoxysilane, 2 parts of acetic anhydride, 63 parts of water and 63 parts of azeotropic alcohol isobutanol were used.
A paint was prepared in the same manner as in. The obtained paint is used in Example 1.
It evaluated by the method similar to. The results are shown in Table 1. By the way, the water content in the reaction solution and the paint was 3% and 0.5%, respectively.

Example 5 Example 4 except that tetraethoxysilane was 62 parts, methyltriethoxysilane was 217 parts, acetic anhydride was 2 parts, water was 61 parts, and azeotropic alcohol isobutanol was 61 parts. Two
A paint was prepared in the same manner as in. The obtained paint is used in Example 1.
It evaluated by the method similar to. The results are shown in Table 1. By the way, the water content in the reaction solution and the paint was 4% and 0.6%.

Comparative Example 1 Thermosetting silicone resin YR3370 (Toshiba Silicone Co., Ltd., trade name, which is a partial condensate of methyltrisilanol)
To 100 parts of solid content (100%), 233 parts of a mixed solvent of an equal amount of isopropanol and propylene glycol monomethyl ether was added to prepare a binder solution having a solid content of 30%. 1000 parts of the silica powder of Example 1 was mixed and stirred with this to prepare a coating material. The obtained coating material was evaluated in the same manner as in Example 1. The results are shown in Table 1.

Comparative Example 2 A coating composition was prepared in the same manner as in Example 2 except that 266 parts of methyltriethoxysilane, 160 parts of water, 160 parts of isobutanol as an azeotropic alcohol were used, and tetraethoxysilane was not used. did. The obtained coating material was evaluated in the same manner as in Example 1. The results are shown in Table 1. By the way, the water content in the reaction solution and the paint was 3% and 0.5%, respectively.

Example 6 A coating material was prepared in the same manner as in Example 1 except that the amount of silica powder was 2000 parts. The obtained coating material was evaluated in the same manner as in Example 1. The results are shown in Table 2. By the way, the water content in the reaction solution and the paint was 4% and 0.4%.

Example 7 A coating material was prepared in the same manner as in Example 5 except that the amount of silica powder was 2000 parts. The obtained coating material was evaluated in the same manner as in Example 1. The results are shown in Table 2. By the way, the water content in the reaction solution and the paint was 3% and 0.3%.

Example 8 Tetraethoxysilane was 173 parts, methyltriethoxysilane was 133 parts, water was 106 parts, and the diluting alcohol isopropanol was 87 parts, except that azeotropic distillation after the hydrolysis reaction was not carried out. A coating material was prepared in the same manner as in Example 1. The obtained coating material was evaluated in the same manner as in Example 1.
The results are shown in Table 2. By the way, the water content in the reaction liquid and the paint after dilution was 15% and 4%.

Comparative Example 3 A coating material was prepared in the same manner as in Comparative Example 1 except that the silica powder was 2000 parts. The resulting paint was tested in the same manner as in Example 1. The results are shown in Table 2.

Comparative Example 4 Snowtex C (colloidal silica, SiO ₂ solid content 20
%, Moisture 80%, Nissan Chemical Co., Ltd., trade name) 250 parts,
1 part of acetic anhydride was added to 133 parts of methyltriethoxysilane (TSL8123, manufactured by Toshiba Silicone Co., Ltd.), and the hydrolysis reaction was carried out at 20 to 50 ° C. for 24 hours. As a result, a reaction solution containing 100 parts of solid content consisting of 50% of SiO ₂ derived from colloidal silica and 50% of silanol and / or its partial condensate was obtained. 116 parts of isopropanol was added to this reaction solution to prepare a reaction solution having a solid content of 20%. Using this solution as a binder component, 1000 parts of the silica powder of Example 1 was mixed and stirred to prepare a coating material.
The obtained coating material was evaluated in the same manner as in Example 1. The results are shown in Table 2.

Example 9 To 10 parts of the reaction solution having a solid content of 30% prepared in Example 1, 100 parts of silica powder having an average particle size of 150 μ and 7 parts of xylene were added and mixed with stirring to prepare a coating material. did. The obtained paint was cast into a ceramic bathtub-type wire wound resistor having a length of 9 mm, a width of 48 mm, and a depth of 8 mm, air-dried for 10 hours to evaporate the solvent, and then heat-cured at 120 ° C. for 10 minutes. . The performance test of the coating film of this product and the smoke emission test at the time of overload energization were conducted by the following methods. The results are shown in Table 3. Coating strength : The pencil hardness of the coating was measured. Solvent resistance : The pencil hardness of the coating film was measured after ultrasonic cleaning using trichlene for 5 minutes. Boil test : The pencil hardness of the coating film after being immersed in boiling water for 48 hours and dried at room temperature was measured. Non-flammability test : Apply a voltage 10 times the rated voltage of the resistor to generate heat by overloading, and observe the presence or absence of smoke from the coating and the duration of smoke generation. The presence or absence was observed.

Example 10 A coating composition similar to that of Example 9 was prepared, except that the reaction solution prepared in Example 7 and having a solid content of 30% was used, and was evaluated in the same manner as in Example 9. . The results are shown in Table 3.

Comparative Example 5 A coating material similar to that of Example 9 was prepared, except that the reaction solution prepared in Comparative Example 1 and having a solid content of 30% was used, and evaluated in the same manner as in Example 9. . The results are shown in Table 3.

Comparative Example 6 A coating composition similar to that of Example 9 was prepared, except that the reaction solution prepared in Comparative Example 4 and having a solid content of 20% was used, and was evaluated in the same manner as in Example 9. . The results are shown in Table 3.

[0029]

[Table 1]

[0030]

[Table 2]

[0031]

[Table 3]

[Brief description of drawings]

FIG. 1 is a diagram showing a situation of a coating film strength test in Examples.

[Explanation of symbols]

1; Iron jig 2; resistor (5.0 mm φ x 12.0 mm) 3; coating film (film thickness 0.25 ± 0.02 mm) 4; Iron support W; load

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Hiroshi Kimura             6-2-1, Roppongi, Minato-ku, Tokyo Toshiba             Inside Ricorn Co., Ltd. (72) Inventor Toshifumi Hashimoto             1-8-3 Shimbashi, Minato-ku, Tokyo Japan Pell             Notx Co., Ltd. (72) Inventor Yuji Zuji             1-8-3 Shimbashi, Minato-ku, Tokyo Japan Pell             Notx Co., Ltd. (72) Inventor Mitsuo Ishizaka             1-8-3 Shimbashi, Minato-ku, Tokyo Japan Pell             Notx Co., Ltd.

Claims (3)

[Claims] (1) 10 to 80 parts by weight of a silane represented by the general formula: SiX ₄ ... (I) (wherein X represents a hydroxyl group or a hydrolyzable group) and the general formula: RSiY ₃ (II) (In the formula, R represents an alkyl group having 1 to 3 carbon atoms, and Y represents a hydroxyl group or a hydrolyzable group) 20 to 90 parts by weight of an alkylsilane, which is obtained by cohydrolysis condensation and is heat-cured. Non-flammable coating material for electronic parts, consisting of 100 parts by weight of a binder component composed of a transparent silicone resin and (2) 400 to 9000 parts by weight of an inorganic pigment. 2. A silane of formula (I) and (II) is cohydrolyzed and condensed in the presence of water to prepare a binder component,
A method for producing a non-combustible coating material for electronic parts, which comprises a step of removing water after co-hydrolytic condensation of silane when the inorganic coating material is further mixed to prepare the coating material according to claim 1. 3. An electronic component coated with the nonflammable coating composition according to claim 1.