JPH0414152B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a polyester insulating paint for coating electric wires, and more specifically, it relates to a polyester insulating paint that has excellent solvent resistance and moist heat resistance, which were conventionally inferior in this type of insulated wire, and can be made at high wire speeds. It provides: Conventional polyester-based insulated wires have relatively well-balanced properties such as electrical properties, mechanical properties, and heat resistance properties, and can be produced at relatively low cost, so the amount of polyester-based insulated wires used has increased rapidly over the past 20 years. It is the most widely used general-purpose electric wire. However, due to recent rationalization and labor saving in manufacturing processes for motors, transformers, etc., polyester insulated wires are increasingly being used in fields where polyester insulated wires have not been used in the past. For example, they are increasingly being used in the presence of moisture or in a sealed state. Recently, there has been an increase in the number of impregnated varnishes using styrene as a reactive diluent, but conventional polyester insulated wires are easily hydrolyzed when used in the presence of moisture or in a sealed state. It is known that insulation performance deteriorates within an extremely short period of time. Furthermore, it has been revealed that the insulation performance after being impregnated with a solvent-free impregnating varnish using styrene or the like as a reactive diluent is considerably inferior to that of other insulated wires. In addition, due to the recent rise in raw material prices, the production price of polyester insulated wires continues to rise, and in order to expand its use as general-purpose wires, there is a demand for polyester insulating paints that can be produced at as low a price as possible. has been done. In view of the current situation, the inventors have developed an insulated wire that overcomes the shortcomings of conventional polyester insulating paints, that is, has excellent heat and humidity resistance and resistance to solvents such as styrene, greatly improves baking workability, and manufactures insulated wires at low cost. The present invention was achieved as a result of intensive studies to obtain a possible polyester-based insulating paint. That is, the present invention provides (a) general formula (However, in the formula, R: C ₁ to C ₄ alkyl group,
(b) General formula H _{2 N} -R- _{NH 2} (wherein, R is aromatic, aliphatic, or aliphatic) ring group residue)
Adding 2 to 20 parts by weight of polyamide-imide oligomer (C) obtained by reacting 1 to 1.5 moles of the diamine represented by 1 to 100 parts by weight of a polyester resin having two or more crosslinkable hydroxyl groups in one molecule. This insulating paint is made by dissolving this in an organic solvent. In the present invention, first, the hexaalkyl ester compound of formula (1) and diamine are reacted to obtain a polyamideimide oligomer, but the reaction ratio of the hexaalkyl ester compound and diamine is 1:1 to
The reason for limiting it to 1.5 mol is that if the molar ratio of hexaalkyl ester compound/diamine is 1/1 or more, the formation of imide rings will be small and the molecular weight will be small.
It becomes inferior in heat resistance and flexibility, and
This is because if it is less than 1.5, all the alkyl esters will react, producing a large amount of amide bonds, and the remaining alkyl esters that will serve as crosslinking components will disappear. The diamines used here include 4,4'-diaminodiphenylmethane, 4,4'-diaminodiphenyl ether, toluylene diamine, m-phenylene diamine, p-phenylene diamine, xylylene diamine, isophorone diamine, Hexamethylene diamine and the like are used. Next, the polyester resin used in the present invention is not particularly limited, but is generally synthesized from aromatic and aliphatic dicarboxylic acids or their dialkyl esters and divalent, trivalent or higher polyhydric alcohols. Examples of aromatic dicarboxylic acid dialkyl esters include dimethyl terephthalate, dimethyl isophthalate, and dimethyl phthalate. As the aliphatic dicarboxylic acid dialkyl ester, dimethyl succinate, dimethyl adipate, etc. are generally used. As the dihydric polyhydric alcohol, ethylene glycol, propylene glycol, butanediol, cyclohexanedimethanol, etc. are used. Examples of trivalent or higher polyhydric alcohols include glycerin, trimethylolpropane, pentaerythritol, neopentyl glycol, and tris-2-hydroxyethyl isocyanurate. In the present invention, the amount of polyamide-imide oligomer obtained from a hexaalkyl ester compound and diamine is limited to 2 to 20 parts by weight per 100 parts by weight of the polyester resin. In this case, the crosslinking effect of the polyamide-imide oligomer is poor, and there is hardly any improvement in solvent resistance, moist heat resistance, baking workability, etc. In addition, if the amount is 20 parts by weight or more, no further improvement in the properties is observed, and on the contrary, flexibility and wire-making workability are hindered. Next, the present invention will be explained by giving Examples and Comparative Examples. Reference example 1 Cresol 1000 in a four-necked flask equipped with a stirrer, nitrogen inlet tube, thermometer, and Liebig condenser.
g, 198 g of 4,4'-diaminodiphenylmethane
(1 mol), 546 g (1 mol) of a hexamethyl ester compound (1,4-Bis(5-carboxymethylpentane)-1,2,3,4-tetracarboxymethylbutane) represented by the following formula (2). Preparation 100℃
Raise the temperature at a rate of 20℃/hr,
The reaction was completed at 180℃ while distilling methanol, and diluted with cresol and naphtha to a concentration of 40℃.
% polyamideimide oligomer solution was obtained. Reference Example 2 Into the same four-necked flask as used in Reference Example 1, 1000 g of cresol, 260.0 g (1.3 mol) of 4,4'-diaminodiphenyl ether, and hexamethyl shown by formula (2) in Reference Example 1 were added. 546 g of an ester compound was charged and reacted in the same manner as in Reference Example 1 to obtain a polyamideimide oligomer having a concentration of 40%. Reference Example 3 194 g of dimethyl terephthalate, 99.2 g of ethylene glycol, 36.8 g of glycerin, and 1 g of lead acetate were placed in a four-necked flask equipped with a stirrer, nitrogen inlet tube, thermometer, and Liebig condenser, and reacted at 140 to 220°C. , after distilling off methanol,
A reduced compression reaction was carried out at 160 to 220°C to distill off excess ethylene glycol, yielding 273 g of polyester resin. Next, this was dissolved in a mixed solvent of cresol/naphtha to a concentration of 40%, and tetrabutyl titanate was added thereto in an amount of 6% based on the resin content to modify the solution to obtain a polyester insulation paint. Reference Example 4 In the same four-necked flask as used in Reference Example 3, 194 g of dimethyl terephthalate, 37.3 g of ethylene glycol, 27.6 g of glycerin, and Tris-2-
After charging 78.3g of hydroxyethyl isocyanurate and 1g of lead acetate and raising the temperature to 150℃,
190 while distilling methanol at a heating rate of hr.
℃, and when the content becomes viscous, add cresol/naphtha, then dissolve it in a mixed solvent of cresol/naphtha to a concentration of 4.0% at around room temperature, and add to it the resin content. ,
6% tetrabutyl titanate was added and modified to obtain a polyester insulation paint. Examples 1 to 8, Comparative Examples 1 to 4 The polyamide-imide oligomer 40% solution obtained in Reference Examples 1 and 2 and the polyester insulation paint obtained in Reference Examples 3 and 4 were mixed in terms of resin content as shown in Table 1. A polyester-based insulating paint was obtained by mixing and stirring at 60° C. for 2 hours.

[Table] The insulating paint of the present invention and the comparative insulating paint thus obtained were each applied to a copper wire of 1.0 mmφ, and
The process of baking at .degree. C. was repeated six times to produce an insulated wire with a coating thickness of 35 microns, and the electrical properties and other performances of the obtained insulated wire were measured. The results are shown in Table 2.

【table】

【table】

【table】

[Table] As is clear from the examples above, the polyester insulating paint of the present invention can provide polyester resin insulated wires with particularly excellent heat and humidity resistance and solvent resistance, and its practicality is extremely high. It's big.

Claims (1)

[Claims] 1 (a) General formula (However, in the formula, R: C ₁ to C ₄ alkyl group,
(b) General formula H _{2 N} -R- _{NH 2} (wherein, R is aromatic, aliphatic, alicyclic residue)
Adding 2 to 20 parts by weight of polyamide-imide oligomer (C) obtained by reacting 1 to 1.5 moles of the diamine represented by 1 to 100 parts by weight of a polyester resin having two or more crosslinkable hydroxyl groups in one molecule. An insulating paint made by dissolving this in an organic solvent.