JPS606978B2 - Manufacturing method of electrical insulation paint - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing a novel electrically insulating paint based on a polyester resin having excellent heat resistance.

Heat-resistant resins such as polyester resins are generally produced by reacting polyhydric alcohols with polyhydric carboxylic acids or alkyl esters of polyhydric carboxylic acids. As a result of investigation from a completely different angle from these conventional methods, the present inventors have found that a polyester having excellent properties can be obtained by using three components as main components: cyanuric acid, alkylene carbonate, and lower alkyl ester of polyhydric carboxylic acid. The present invention was achieved by discovering that a system resin can be obtained. That is, a lower alkyl ester of a polyhydric carboxylic acid alone or a mixed brewing ingredient in which one part thereof is replaced with a polyhydric carboxylic acid anhydride, cyanuric acid, and alkylene carbonate in a molar ratio at least twice that of the cyanuric acid. It is characterized by dissolving in a solvent a polyester resin obtained by heating and reacting a mixture in which 1 part of the mixture is mixed with a polyhydric alcohol or/and a polyhydric amine. be. As described above, the present invention uses the three components of cyanuric acid, alkylene carbonate, and lower alkyl ester of polyhydric carboxylic acid as essential components to obtain a polyester resin with excellent properties. A polyester resin having the desired excellent heat resistance cannot be produced by reacting only a mixture of alkylene carbonate and a lower alkyl ester of a polycarboxylic acid or a mixture of cyanuric acid and alkylene carbonate.

Next, in the reaction for synthesizing a polyester resin in the present invention, the proportion of each component in the reaction system is at least 2 moles, preferably 2 to 4 moles, of alkylene carbonate per mole of cyanuric acid. In addition, when using a polyvalent carboxylic acid anhydride and not using a polyvalent alcohol or a polyvalent amine, in addition to the amount added to cyanuric acid, add 0 alkylene carbonate to 1 mole of the polyvalent carboxylic acid anhydride. It is preferable to add about 8 to 3 moles. Lower alkyl ester of polycarboxylic acid alone or a mixture of cyanuric acid or a mixture in which one part thereof is replaced with polyhydric alcohol or polyhydric amine as a brewing ingredient with one part replaced with polyhydric carboxylic acid anhydride The ratio is preferably in the range of 0.8 to 1.3 in terms of molar ratio. The alkylene carbonate used in the present invention refers to ethylene carbonate, propylene carbonate, and the like.

Also, lower alkyl esters of polyvalent carboxylic acids such as dimethyl terephthalate, dimethyl isophthalate, dimethyl phthalate, trimethyl trimellitate, dimethyl succinate,
It refers to lower alkyl esters of divalent or higher polybasic acids such as dimethyl benzophenonedicarboxylate, diethyl terephthalate, and diethyl isophthalate. In addition, examples of polyhydric carboxylic acid anhydrides include trimellitic anhydride,
It refers to three or more polybasic acid anhydrides such as benzophenone tetracarboxylic dianhydride. Further, the term "polyhydric alcohol" refers to polyhydric alcohols having a valence of two or more, such as ethylene glycol, glycerin, trimethylolpropane, butanediol, triethanolamine, hydroxyethyl ether, and 1.4-cyclohexanedimethanol. Polyvalent amines include, for example, 4,4 diamine diphenylmethane, tolylene diamine, hexamethylene diamine, 3,3 dimethyl 4,4' diaminodiphenyl methane, 3,3 dicarpoxy 4,4 diaminodiphenyl methane, xylylene diamine, etc. This refers to diamines such as amines. The present invention also provides a solvent for the above reaction components, such as N
- By carrying out the reaction using methylpyrrolidone, dimethylacetamide, dimethylformamide, solvent naphtha, etc., the reaction is uniformly promoted.

Further, by using, for example, lead acetate, lead oxide, antimony trioxide, tin oxalate, etc. as a catalyst during the reaction, the reaction efficiency can be improved and the reaction can be carried out quickly. Note that cresol, which is widely used in electrical insulation paints, is suitable as a solvent for dissolving the polyester resin obtained according to the present invention.

Note that it is effective to modify the polyester electrical insulating paint provided by the present invention by adding a modifier such as a tetraalkyl titanate, polyisocyanate, phenol resin, melamine resin, or epoxy resin. Next, examples of the present invention will be described.

Example 1 129 g of cyanuric acid, 264 g of ethylene carbonate, 194 g of dimethyl terephthalate, 150 g of dimethylformamide as a reaction solvent, and 1 g of lead acetate as a catalyst were placed in a flask equipped with a dehydrator and a condenser. The temperature was gradually heated to 200°C, taking about 1 hour to raise the temperature. During this time, methanol and dimethylformamide were distilled out, and the reaction was carried out. Cresol was then added to the reaction product. Dissolved, concentration 30%, viscosity 3
6 ratio. A clear solution of P (30°C) was obtained.

Apply this resin solution to the copper wire on the 1.0 side and bake it at 400 qo seven times to obtain a film thickness of 4.
A 0r insulated wire (referred to as a product of the present invention) was obtained. The breakdown voltage and other characteristics of this insulated wire were measured and the results are shown in Table 1.

Comparative Example 1 A paint in which a polyester resin synthesized from 1.0 mol of dimethyl terephthalate, 0.7 mol of ethylene glycol, and 0.4 mol of glycerin was dissolved in cresol,
Characteristics were also measured for an insulated wire (referred to as conventional product) with a film thickness of 41 mm obtained by coating and baking on a conductor in the same manner as in Example 1, and the results are also listed in Table 1.

Table 1 Example 2 The same procedure was used as in Example 1 except that 300% of propylene carbonate was used instead of ethylene carbonate in Example 1, so that the concentration was 30% and the viscosity was 29%. A clear solution of P(3000) was obtained.

This resin solution was prepared in the same manner as in Example 1. An insulated wire with a coating thickness of 45 mm was obtained by coating it on a copper wire. When the breakdown voltage of the insulated wire thus obtained was measured, it showed 1 V under normal conditions, and 10 kV after heating at 250 qo for 5 days. Moreover, the heat-resistant softening temperature (load lk9) was 349°C. Example 3 Cyanuric acid 64.5 times, ethylene carbonate 165 times, ethylene glycol 32 times, dimethyl terephthalate 196 times,
1 liter of lead acetate and 150 liters of solvent naphtha were placed in a container similar to Example 1, and the mixture was gradually heated.
The temperature was raised to 220°C over about 1 hour, during which the reaction was carried out while methanol and solvent naphtha were distilled out, and then cresol was added to dissolve the reaction product to give a concentration of 30% and a viscosity of 29. ratio. P(3000
) was obtained.

Add this resin solution to 1. Apply 40,000 coats and bake them on the copper wire of Qiu ◇ 7 times to obtain a film thickness of 3.
Obtained an insulated wire.

When the breakdown voltage of the insulated wire thus obtained was measured, it showed 11 kV under normal conditions, and 8 kV after 240 qo×1 week. Also heat resistant softening temperature (load lk9)
was 34,500. Example 4 Cyanuric acid 65 days, ethylene carbonate 150 days, dimethyl terephthalate 100 days, trimellitic anhydride 38 days, 4 days
・20 tons of 4-diaminodiphenylmethane, 0.5 tons of lead acetate, and 100 tons of dimethylformamide were placed in the same container as in Example 1, and the mixture was gradually heated under reduced pressure over about 2 hours. Then, the temperature was raised to 210°C, and the remaining dimethylformamide was distilled out and condensed to form a viscous resin solution. Cresol was then added and melted to give a concentration of 30% and a viscosity of 30%. 40 ratio. A solution of P (30°C) was obtained.

Claims (1)

[Claims] 1 A lower alkyl ester of a polyhydric carboxylic acid alone or a mixed acid component in which one part thereof is replaced with a polyhydric carboxylic acid anhydride, cyanuric acid, and a molar ratio of at least 2 to cyanuric acid.
It is characterized by dissolving in a solvent a polyester resin obtained by heating and reacting a mixture to which more than double the amount of alkylene carbonate has been added, or a mixture in which one part of the mixture has been replaced with a polyhydric alcohol or/and a polyhydric amine. A method for producing an electrically insulating paint.