JP3256669B2 - Coating compositions for electrical insulation and shielding of corrosive gases - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a coating composition for electrical insulation and for shielding corrosive gas. More specifically, the present invention relates to a polyurethane resin-based coating composition that is excellent in corrosive gas shielding properties, long-term insulation properties, thermal stability, and provides a tough coating film and is suitable for electronic and electric equipment.

[0002]

2. Description of the Related Art In recent years, in order to obtain electronic equipment having high reliability, an electric circuit portion and a terminal portion are often coated with a polyurethane-based or silicone-based coating of a hardening type using a drying oil. These coatings give a flexible coating,
It is possible to prevent dust and the like from adhering to the electric circuit portion and the terminal portion and to prevent moisture from entering, and to suppress the occurrence of leakage current due to dew condensation. Therefore, generation of ion migration of the conductive metal can be suppressed, and as a result, an electronic device having higher reliability can be obtained.

[0003]

However, in the case of conventional polyurethane-based or silicon-based coating materials,
There is a problem that the shielding resistance in an acidic gas atmosphere such as hydrogen sulfide and sulfur dioxide is insufficient.In electric and electronic equipment used in such an environment, these metals and sulfides are used in copper and silver electrodes. Since it forms and grows, there is a problem of causing an electrical short or the like.

When a coating is applied to a portion where a potential difference exists, such as a circuit portion or a terminal portion, the atmosphere becomes 85%.
When used for a long period of time in a high-temperature and high-humidity environment such as 85 ° C. and 85% RH, the main chain was cut off due to hydrolysis, and it was found that there was a problem that the coating film performance and insulation properties were reduced.

The present invention solves the above-mentioned conventional problems by providing an electronic / electrical material which is excellent in shielding property against corrosive gas such as hydrogen sulfide and sulfur dioxide, thermal stability, long-term insulating property and has a tough coating film. An object is to provide a coating composition suitable for equipment.

[0006]

Means for Solving the Problems The present inventors have conducted intensive studies on the above problems, and as a result, a specific polyurethane resin has excellent corrosive gas shielding properties, long-term insulation properties, and thermal stability. The inventors have found that a tough coating film is provided, and have reached the present invention.

That is, according to the present invention, an aromatic dicarboxylic acid is contained in an amount of 80 to 100 mol%, other dicarboxylic acids are contained in an amount of 20 to 0 mol%, and a glycol component is composed of an aliphatic and / or alicyclic diol. Number average molecular weight 50
0-6000 polyester diol (A), organic diisocyanate compound (B), and, if necessary, a molecular weight of 50
A chain extender (C) of less than 0 was reacted at a ratio shown in the following formula (1), and the urethane group concentration was 500 to 5000 equivalent / 1.
0 ⁶ g, a glass transition temperature of 35 ° C. or higher, and intended to provide a polyurethane resin which is the reduced viscosity 0.3~2.0dl / g, and an electrical insulating and corrosive gas shielding coating composition comprising a solvent is there.

0.8 <(B) / ((A) + (C)) ≦ 1 (equivalent ratio) (1)

The present invention also provides the above composition, wherein the aromatic dicarboxylic acid is at least one member selected from the group consisting of terephthalic acid, isophthalic acid and orthophthalic acid.

[0010] The present invention further provides at least one of the glycol components selected from the group consisting of ethylene glycol, diethylene glycol, 1,5-pentanediol, 1,6-hexanediol, neopentyl glycol and 1,4-cyclohexanedimethanol. It is intended to provide a composition as described above which is seed.

Further, the present invention relates to (B) / ((A) +
(C)) is from 0.95 to 0.99.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION The coating composition for electrical insulation and corrosive gas shielding comprising a specific polyurethane resin and a solvent according to the present invention comprises a polyester diol (A), an organic diisocyanate compound (B) and, if necessary, a molecular weight. It can be obtained using less than 500 chain extenders (C) and organic solvents.

The dicarboxylic acid component of the polyester diol (A) used in the present invention includes terephthalic acid, isophthalic acid, orthophthalic acid, 4,4'-diphenyldicarboxylic acid, indenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid and the like. As aromatic dicarboxylic acids and other dicarboxylic acids, oxalic acid, succinic acid, glutaric acid, adipic acid, azelaic acid, sebacic acid, dodecandionic acid and other aliphatic dicarboxylic acids and fumaric acid, tetrahydrophthalic acid, methyltetrahydro Phthalic acid, hexahydrophthalic acid, hexahydroterephthalic acid, methylhexahydrophthalic acid, 1,4-cyclohexanedicarboxylic acid, 1,2-cyclohexanedicarboxylic acid, 1,3-
Examples thereof include unsaturated aliphatic carboxylic acids such as cyclohexanedicarboxylic acid, dimer acid, and hydrogenated dimer acid, and alicyclic dicarboxylic acids. Among these dicarboxylic acid components, the aromatic dicarboxylic acid is 80 to 100 mol%, and the other dicarboxylic acids are 20 to 0 mol%, preferably 10 to 0 mol%, of all the acid components. . If the aromatic dicarboxylic acid in the total acid component is less than 80 mol%, the rigidity of the main chain is impaired, so that not only the heat resistance such as a decrease in the glass transition temperature (Tg), but also the heat resistance is lowered, The permeation speed of relatively large molecules such as hydrogen disulfide and sulfur dioxide increases, and the corrosive gas shielding properties of these sulfur gases and the like decrease. Desirable aromatic dicarboxylic acids are terephthalic acid, isophthalic acid and orthophthalic acid, and other desirable carboxylic acids are adipic acid, azelaic acid and sebacic acid.

The glycol component of the polyester diol (A) used in the present invention includes ethylene glycol, propylene glycol, trimethylene glycol,
1,3-butanediol, 1,4-butanediol,
1,5-pentanediol, 1,6-hexanediol, neopentyl glycol, 2-methyl-1,3-propanediol, 3-methyl-1,5-pentanediol, 2-ethyl-2-butyl-1, 3-propanediol, diethylene glycol, 1,9-nonanediol,
Aliphatic di-acids such as an alkylene oxide adduct of bisphenol A, an alkylene oxide adduct of bisphenol F, and an alkylene oxide adduct of bisphenol F
And alicyclic diols such as 1,4-cyclohexanediol, 1,4-cyclohexanedimethanol, 1,3-cyclohexanedimethanol, and 1,2-cyclohexanedimethanol. Among the above glycol components, ethylene glycol, diethylene glycol, 1,5-pentanediol, 1,6-hexanediol, neopentyl glycol, 1,4-cyclohexanedimethanol and the like are preferable. Also, a small amount of trifunctional or higher polycarboxylic acid or polyol may be used.
Trifunctional or higher polycarboxylic acids and polyols include trimellitic anhydride, pyromellitic anhydride, glycerin,
Trimethylolpropane, pentaerythritol and the like.

The polyester diol (A) obtained using the above dicarboxylic acid and glycol component must have a number average molecular weight of 500 to 6000, preferably 1500 to 4000. If the number average molecular weight is less than 500, the urethane group concentration becomes too high, so that the solubility is reduced, the film becomes brittle, and the shielding property against corrosive gas such as sulfur gas is also reduced. When the number average molecular weight exceeds 6000, the content of the isocyanate group becomes small, the adhesive strength to the resin is reduced, and for the above-mentioned reason, the insulating properties in a high-temperature and high-humidity environment are reduced. In addition, the viscosity of the resin becomes very large, and handling as a coating material becomes difficult.

The organic diisocyanate compound (B) used in the present invention includes tetramethylene diisocyanate, hexamethylene diisocyanate, tolylene diisocyanate, diphenylmethane diisocyanate, xylylene diisocyanate, hydrogenated diphenylmethane diisocyanate, isophorone diisocyanate, hydrogenated xylylene diisocyanate, and the like. Is mentioned. Particularly preferred are hexamethylene diisocyanate, diphenylmethane diisocyanate, xylylene diisocyanate, isophorone diisocyanate and the like.

The molecular weight of 50 used in the present invention as required.
Examples of the chain extender (C) of less than 0 include ethylene glycol having an active hydrogen group, 1,5-pentanediol,
1,6-hexanediol, neopentyl glycol,
1,4-cyclohexanedimethanol and the like can be mentioned.

The polyester diol (A), the organic diisocyanate compound (B) and, if necessary, a molecular weight of 5
A chain extender (C) having a urethane group concentration of 500 to 5000 equivalents / 10 ⁶ g, a glass transition point temperature of 35 ° C. or higher, and a reduced viscosity of 0 It is possible to obtain a polyurethane resin of 0.3 to 2.0 dl / g.

0.8 <(B) / ((A) + (C)) ≦ 1 (equivalent ratio) (1)

Preferably, (B) / ((A) + (C)) is 0.95 to 0.99. (B) / ((A) +
When (C)) is 0.8 or less, the reduced viscosity becomes smaller than the above reduced viscosity, the flexibility of the coating film is impaired, and the coating film becomes brittle at low temperature,
In addition, insulation properties are also reduced. Also, (B) / ((A) +
When (C)) exceeds 1, isocyanate groups remain, so that handling as a coating composition becomes extremely difficult, and properties such as insulating properties deteriorate.

[0021] The coating composition of the present invention is produced by a known method. That is, 25 ° C to 150 ° C in a solvent.
It is manufactured in the presence of a catalyst or in the absence of a catalyst. Solvents used at this time include ketones such as methyl ethyl ketone, cyclohexanone, cyclooctanone, cyclodecanone, isophorone methyl isobutyl ketone, methyl isoamyl ketone, ethyl amino ketone diisobutyl ketone, aromatic hydrocarbons such as toluene and xylene, and acetic acid. Ester such as ethyl, methyl acetate, isopropyl acetate, isobutyl acetate, butyl acetate, amyl acetate, carbitol (diethylene glycol monoethyl ether), butyl carbitol (diethylene glycol monobutyl ether), methyl carbitol acetate, ethyl carbitol acetate, acetic acid It is a polyhydric alcohol derivative such as butyl carbitol. As the catalyst, organic tin compounds such as dibutyltin laurate, stannas octoate, dimethyltin dichloride, trimethyltin hydroxide, stannic chloride, and amines such as diethylethanolamine and triethylenediamine are used.

After the polyester diol (A), the organic diisocyanate compound (B) and, if necessary, the chain extender (C) having a molecular weight of less than 500 are reacted with the coating composition of the present invention, The organic diisocyanate compound (B) may be used in a dissolved form. The mixture of the polyester diol (A), the chain extender (C) having a molecular weight of less than 500 and a catalyst, if necessary, dissolved in a solvent, and the organic diisocyanate compound (B) may be used in the solvent. May be mixed and used immediately before use. The resin solids concentration in the composition is usually used in the range of 5 to 80% by weight.

The coating composition of the present invention can be used as it is, but may contain a known organic polyvalent isocyanate compound or a crosslinking agent such as an epoxy resin or an amino resin. By blending and crosslinking the above-mentioned crosslinking agent, chemical resistance, solvent resistance and heat resistance can be improved. Examples of the organic polyvalent isocyanate compound include tetramethylene diisocyanate, hexamethylene diisocyanate, tolylene diisocyanate, diphenylmethane diisocyanate, xylylene diisocyanate, hydrogenated diphenylmethane diisocyanate, isophorone diisocyanate, hydrogenated xylylene diisocyanate, and trimers of these isocyanate compounds. There are bodies. Further, it may be a blocked isocyanate. Examples of the isocyanate blocking agent include phenols such as phenol, thiophenol, methylthiophenol, tetylthiophenol, cresol, xylenol, resorcinol, and nitrophenol, acetoxime, methylethylketoxime, and cyclohexanone oxime. Oximes such as, methanol, ethanol,
Alcohols such as propanol, butanol, etc. In addition, tertiary alcohols, lactams, aromatic amines, imides and the like can also be mentioned. As the epoxy resin, diglycidyl ether of bisphenol A and its oligomer hydrogenated diglycidyl ether of bisphenol A and its oligomer diglycidyl orthophthalate, diglycidyl isophthalate, diglycidyl terephthalate, dihydrohexaphthalate Glycidyl ester, adipic acid diglycidyl ester, sebacic acid diglycidyl ester, ethylene glycol diglycidyl ether, 1,6-hexanediol diglycidyl ether and polyalkylene glycol glycidyl ethers trimellitic acid triglycidyl ester are available. , Methoxylated methylol urea, methoxylated methylol melamine, methoxylated methylol benzoguanamine, butoxylation Methylol melamine, butoxylated methylol benzoguanamine, methoxylated methylol dicyandiamide and the like can be used alone or in combination.
The method for applying the coating composition of the present invention includes spraying,
Known methods such as dipping, brushing, and roll coating can be adopted, and an optimum method is selected according to the shape of the object to be coated, the thickness of the coating film, workability, and the like.

[0024]

EXAMPLES The present invention will now be described specifically with reference to examples, but the present invention is not limited to these examples. In the examples, parts and% are based on weight. Each measurement item followed the following method.

(Number Average Molecular Weight) The number average molecular weight in terms of polystyrene was measured using GPC. The solvent is THF
Was used. (Glass transition point temperature) The temperature was measured at a heating rate of 20 ° C./min using a differential scanning calorimeter (DSC). The sample was used by crimping 5 mg of a sample in an aluminum holding lid type container. (Reduced Viscosity) ηSP / C (dl / g) 0.1 g of a polyurethane resin was dissolved in 25 cc of a phenol / tetrachloroethane = (weight ratio: 6/4) mixed solution and measured at 30 ° C.

Synthesis Example of Polyester Diol (Synthesis Example of A-1) In a reaction vessel equipped with a thermometer, a stirrer, and a partial reflux condenser, 466 parts of dimethyl terephthalate, 466 parts of dimethyl isophthalate, 488 parts of ethylene glycol, Charged with 400 parts of pentyl glycol and catalyst, 14
The transesterification was performed at 0 ° C to 210 ° C for 4 hours. Subsequently, the pressure of the reaction system was reduced to 10 mmHg over 90 minutes, and a polycondensation reaction was further performed at 230 ° C. at 1 mmHg or less for 30 minutes. The obtained polyester diol (A-1) had a number average molecular weight of 2,400 and a hydroxyl value of 45 mgKOH / g.
Met. Further, the obtained polyester diol (A-
As a result of analyzing 1) by NMR, the composition was terephthalic acid 5
0 mol%, 50 mol% of isophthalic acid, 50 mol% of ethylene glycol, and 50 mol% of neopentyl glycol.

Synthesis Example of Polyester Diol (Synthesis Example of A-2) In a reaction vessel equipped with a thermometer, a stirrer, and a partial reflux condenser, 469 parts of dimethyl terephthalate, 375 parts of dimethyl isophthalate, 587 parts of ethylene glycol, ,
138 parts of 6-hexanediol and a catalyst were charged, and 1
The transesterification was performed at 40 ° C to 210 ° C for 4 hours.
Cool and charge 98 parts of sebacic acid at 170 ° C, 220 ° C
For 2 hours. Subsequently, the pressure of the reaction system was reduced to 10 mmHg over 90 minutes, and the pressure was further reduced at 230 ° C to 1 mm.
The polycondensation reaction was performed at 50 mmHg or less for 50 minutes. The obtained polyester diol (A-2) had a number average molecular weight of 3,50.
0, hydroxyl value 32 mg KOH / g. Also,
As a result of NMR analysis of the obtained polyester diol (A-2), the composition was as follows: terephthalic acid 50 mol%, isophthalic acid 40 mol%, sebacic acid 10 mol%, ethylene glycol 40 mol%, 1,6-hexanediol 60 mol% Mole%.

The polyester diol (A-
3) to (A-6) were obtained. Similarly, (A
-7) to (A-9) were obtained. Tables 1 and 2 show the composition of these components, the number average molecular weight, and the like.

Preparation Example of the Coating Composition of the Present Invention (B
Preparation Example 1) Toluene 44 was placed in a reaction vessel equipped with a thermometer and a stirrer.
5 parts, 445 parts of methyl ethyl ketone, 500 parts of polyester diol (A-1), neopentyl glycol 30
Then, 121 parts of diphenylmethane diisocyanate and 0.3 part of dibutyltin laurate as a catalyst were charged therein. The reaction was carried out for 10 hours while controlling the temperature at 80 ° C. Then toluene 33
0 parts and 330 parts of methyl ethyl ketone were charged and stirred for 1 hour to obtain a coating composition B-1) of the present invention. In addition, the obtained polyurethane resin was (B) / ((A) +
(C)) = 0.97, reduced viscosity 0.8 dl / g, urethane group concentration 1380 equivalent / 10 ⁶ g, glass transition temperature (T
g) = 80 ° C., the number average molecular weight was 38,000.

The compositions (B-2) to (B-
6) was obtained. (B-7) to (B-7)
-9) was obtained. (B) of the obtained polyurethane resin /
Tables 3 and 4 show ((A) + (C)), reduced viscosity, number average molecular weight, urethane group concentration, Tg, component composition, and the like.

The above-mentioned compositions (B-1) to (B-9), commercially available coating agents include a dry oil-curable urethane resin (HumiSeal 1A27, manufactured by Boxui Brown) and a secondary-curable urethane resin ( Solitan 113 / Curing agent C1
13-300 Morthon Thiokol) and silicone resin
(Pergan Z, manufactured by Dow Corning), the following evaluation items were performed.

(Long-Term Insulation) A substrate having the shape shown in FIG. 1 was used as a substrate for a long-term insulation resistance test. FIG. 1 is a schematic explanatory view of a substrate for a long-term insulation resistance test. In FIG. 1, reference numerals 1 and 2 denote terminal portions for connection to external electrodes. FIG. 2 is an enlarged view of a portion surrounded by a broken line in the schematic explanatory view of the substrate for long-term insulation resistance test of FIG. 1. In FIG. 2, W indicates a line width and d indicates a gap. The substrate shown in FIG. 1 is a glass epoxy resin laminate (FR-4) having a thickness of 1.6 mm and a line width W of 0.165 mm and a gap d of 0.
40 comb-shaped pattern electrodes of 165 mm were formed of copper. First, the coating composition or coating agent was mixed with a mixture of toluene and methyl ethyl ketone at a mixing ratio of 1: 1 so that the film thickness after drying was 30 ± 5 μm over the entire comb-shaped pattern electrode of the substrate for long-term insulation resistance test. The viscosity was adjusted to a predetermined value using a solvent. The coating composition or the coating agent was dip-coated with a predetermined viscosity on the substrate for insulation resistance test, and dried in a hot-air drying oven set at 60 ° C. for 20 minutes to prepare a sample. Next, the sample was put in a thermo-hygrostat at 85 ° C. and 85% RH, and a voltage of 50 V DC was applied between the comb electrodes 1 and 2 in FIG. 1 to change the electric resistance between the comb patterns with time. A long-term electrical insulation resistance test was performed by measuring. As a criterion, a double circle when the insulation resistance is 10 ⁹ Ω or more after 2000 hours of voltage application, a circle when the insulation resistance is 10 ⁸ Ω or more and less than 10 ⁹ Ω, and a double circle when the insulation resistance is 10 ⁷ Ω or more and less than 10 ⁸ Ω Δ: Less than 10 ⁷ Ω was defined as x.

(Heat Shock Property) A silver-plated copper plate having a thickness of 2 to 3 μm was used as a substrate for a heat shock test. The dimensions of the copper plate are 35mm wide, 50mm long,
The one having a thickness of 2 mm was used. The substrate for the heat shock test was coated with a rust preventive agent (Calonex AG-51, manufactured by Calonex) immediately after silver plating for the purpose of corrosion prevention, and carbon tetrachloride was used before applying the coating agent. The rust preventive was removed. The various coating agents were applied so that the film thickness after drying was 30 ± 5 μm, and then dried in a hot-air drying oven set at 60 ° C. for 20 minutes. One day after drying, using a thermal shock tester,
A test was performed for 1000 cycles, with one cycle of standing at 25 ° C. for 30 minutes and leaving at 85 ° C. for 30 minutes. As a criterion, after 1000 cycles, there is no change such as generation of wrinkles or cracks on the coating applied surface and no peeling at the interface with the substrate, and generation of wrinkles is recognized. When there was no cracking of the coating film and no peeling at the interface with the substrate, it was defined as Δ, and when there was cracking of the coating film or there was peeling at the interface with the substrate, ×.

(Corrosive Gas Shielding Property) As a substrate for evaluating corrosive gas shielding properties, a silver-plated copper plate having a thickness of 2 to 3 μm was used. The dimensions of the copper plate are 35mm wide and 50m long
m and a thickness of 2 mm were used. For the purpose of corrosion prevention, the corrosive gas shielding evaluation substrate was coated with a rust inhibitor (Calonex AG-51, manufactured by Calonex) immediately after silver plating, and carbon tetrachloride was applied before the coating agent was applied. The rust preventive was removed using. The various coating agents were applied so that the film thickness after drying was 30 ± 5 μm, and then dried in a hot-air drying oven set at 60 ° C. for 20 minutes. After drying, the substrate for evaluation of corrosive gas shielding properties to which the coating agent was applied was left for about one day. Using a gas corrosion tester (manufactured by Suga Test Instruments Co., Ltd.), 168 in an atmosphere of 40 ppm of hydrogen sulfide gas, 40 ° C. and 80% RH.
After leaving for a period of time, the substrate for evaluating the corrosive gas shielding property to which the coating agent was applied was taken out, and the peak intensity of the silver element and the peak intensity of the sulfur element were determined by X-ray analysis. Calculated.

Gas shielding ratio I = (Io−Is) / Io × 100 (%)

Here, Is represents the ratio of the peak intensity of the sulfur element to the peak intensity of the silver element when the coating agent is applied, and Io is the sulfur element to the peak intensity of the silver element when the coating agent is not applied. Is the peak intensity ratio. As criteria for determining the corrosive gas shielding properties,
99.9% or more was defined as a double circle, 99% or more to less than 99.9%, 90% or more to less than 99% as Δ, and 90% or less as ×.

(Thermal Stability) As a substrate for evaluating thermal stability,
A silver-plated copper plate having a thickness of 2 to 3 μm was used. The dimensions of the copper plate were 35 mm in width, 50 mm in length, and 2 mm in thickness. The substrate for evaluation of thermal stability was used immediately after silver plating to prevent corrosion.
Before the application of the coating material, the rust preventive was removed using carbon tetrachloride. The various coating agents were applied so that the film thickness after drying was 30 ± 5 μm, and then dried in a hot-air drying oven set at 60 ° C. for 20 minutes. Then 120
It was placed in a hot-air drying oven set at ℃, left for 1000 hours, and then taken out. As an evaluation method, when there is no discoloration and no peeling or cracking of the coating film, there is a double circle, and there is slight discoloration.When there is no peeling or cracking, there is considerable discoloration such as blackening, but no peeling or cracking. In this case, it was defined as “△”, and when peeling or cracking occurred, it was defined as “×”.

Tables 3 to 5 show the results obtained in the various tests described above.

[0039]

[Table 1]

[0040]

[Table 2]

[0041]

[Table 3]

[0042]

[Table 4]

[0043]

[Table 5]

[0044]

The coating composition according to the first aspect of the present invention comprises 80 to 10 aromatic dicarboxylic acids among all the acid components.
0 mol%, other dicarboxylic acid is 20 to 0 mol%, glycol component is aliphatic and / or alicyclic diol, polyester diol having a number average molecular weight of 500 to 6000 (A), organic diisocyanate compound (B) And, if necessary, a chain extender (C) having a molecular weight of less than 500 is reacted at a ratio shown in the above formula (1), the urethane group concentration is 500 to 5000 equivalent / 10 ⁶ g, the glass transition temperature is 35 ° C. or more, and Reduced viscosity 0.3-2.0dl
/ G of polyurethane resin, and a coating composition for electric insulation and corrosive gas shielding comprising a solvent, so that it has excellent gas shielding resistance, long-term insulation, and thermal stability.
In addition, it can form a tough coating film, and is particularly useful for electronic and electric equipment.

The coating composition according to claim 2 of the present invention is characterized in that the aromatic dicarboxylic acid is at least one selected from the group consisting of terephthalic acid, isophthalic acid and orthophthalic acid, so that the gas-shielding resistance and the long-term Insulation,
Thermal stability is further improved, and a tough coating film can be obtained more favorably.

In the coating composition according to the third aspect of the present invention, the glycol component is ethylene glycol, diethylene glycol, 1,5-pentanediol, 1,6-
Hexanediol, neopentyl glycol and 1,
Since it is at least one member selected from the group consisting of 4-cyclohexanedimethanol, gas-shielding properties, long-term insulation properties, and thermal stability are further improved, and a tough coating film can be obtained more favorably.

The coating composition according to claim 4 of the present invention has a ratio (B) / ((A) + (C)) of 0.95 to 0.9.
Since it is set to 9, the gas shielding resistance, the long-term insulation properties, and the thermal stability are further improved, and a tough coating film can be obtained even more favorably.

[Brief description of the drawings]

FIG. 1 is a schematic explanatory view of a substrate for a long-term insulation resistance test.

FIG. 2 is an enlarged view of a portion surrounded by a broken line in the schematic explanatory view of the long-term insulation resistance test substrate of FIG.

[Explanation of symbols]

1, 2 Terminal part for connecting to external electrode, W line width, d gap.

Continuing from the front page (72) Inventor Masami Oka 2-1-1 Katata, Otsu-shi, Shiga Toyo Spinning Co., Ltd. (72) Inventor Hiroshi Tajika 2-1-1 Katata, Otsu-shi, Shiga Toyo Spinning Stock (56) References JP-A-56-32558 (JP, A) JP-A-5-17682 (JP, A) JP-A-8-12936 (JP, A) (58) Fields studied (Int .Cl. ⁷ , DB name) C09D 5/25 C09D 175/04-175/16 H01B 3/30

Claims (4)

(57) [Claims] 1. An aromatic dicarboxylic acid 80 among all acid components.
Polyester diol (A) having a number average molecular weight of 500 to 6000, in which the amount of other dicarboxylic acids is 20 to 0 mol%, and the glycol component is an aliphatic and / or alicyclic diol, and an organic diisocyanate compound (B ) And, if necessary, a chain extender (C) having a molecular weight of less than 500 was reacted at a ratio shown in the following formula (1), the urethane group concentration was 500 to 5000 equivalent / 10 ⁶ g, the glass transition temperature was 35 ° C or more, And reduced viscosity of 0.3 to 2.0 dl
/ G of a polyurethane resin and a solvent, and a coating composition for electric insulation and shielding of corrosive gas. 0.8 <(B) / ((A) + (C)) ≦ 1 (equivalent ratio) (1) 2. The method according to claim 1, wherein the aromatic dicarboxylic acid is terephthalic acid,
The composition according to claim 1, wherein the composition is at least one selected from the group consisting of isophthalic acid and orthophthalic acid. 3. The glycol component is at least one selected from the group consisting of ethylene glycol, diethylene glycol, 1,5-pentanediol, 1,6-hexanediol, neopentyl glycol, and 1,4-cyclohexanedimethanol. The composition according to claim 1. 4. The ratio (B) / ((A) + (C)) is 0.95.
The composition according to any one of claims 1 to 3, wherein the composition is 0.99 to 0.99.