JPH0554722A - Resin composition for electric insulation and insulated wire - Google Patents

Abstract

PURPOSE:To enhance its softening resistance, breakdown voltage retention after degradation due to heating, and solderability, and make it heat resistive equal or superior to B-class. CONSTITUTION:A polyester resin of 100 weight parts obtained by reacting an alcohol component, such that 50 to 90 equivalent % of all alcohols being a tris(2-hydroxyethyl) isocyanate, with a polybasic acid is contained. Next, a block isocyanate resin of 100 to 1,000 weight parts, a reactant of either a tolylenediisocyanate or diphenylmethanediisocyanate and tris(2-hydroxyethyl) isocyanate, a free isocyanate of which being blocked by phenolic species, is contained. Excellent solderability, softening resistance, and dielectric breakdown voltage retention ratio after degradation due to heating with heat resistivity equal or superior to B-class are obtained.

Description

Detailed Description of the Invention

[0001]

The present invention relates to a resin composition for electrical insulation,
More specifically, the present invention relates to a resin composition for electrical insulation, which is capable of obtaining an insulated wire having excellent solderability and heat resistance of B type or more, and an insulated wire using the same.

[0002]

2. Description of the Related Art Conventionally, a polyurethane-based insulated wire has been widely used as an insulated wire having solderability, but the heat resistance of the insulated wire is A to E (heat resistant classification according to the Electrical Appliance and Material Control Law). However, it has a drawback that it cannot be used for applications requiring heat resistance higher than this.

Recently, in order to improve this drawback, after reacting a polyester resin having an imide bond in the molecule and an alcohol component such as trimethylolpropane or glycerin with tolylene diisocyanate or diphenylmethane diisocyanate, the free isocyanate is converted to phenol. It has been proposed to use a resin composition containing a blocked isocyanate resin blocked with a class for an electric wire for class B insulation. However, this insulated wire has drawbacks that it is inferior in softening resistance and dielectric breakdown voltage retention rate after heat deterioration, as compared with the case of using a polyester coating which has been conventionally used for class B insulation.

[0004]

The object of the present invention is to solve the above-mentioned drawbacks of the prior art, to have excellent softening resistance, excellent dielectric breakdown voltage retention rate after heat deterioration, and solderability.
It is an object of the present invention to provide a resin composition for electrical insulation capable of obtaining an insulated electric wire having heat resistance of at least one kind, and an insulated electric wire using the same.

[0005]

The present invention provides a polyester resin 100 obtained by reacting (A) an alcohol component in which 50 to 90 equivalent% of all alcohols is tris (2-hydroxyethyl) isocyanate with a polybasic acid. Parts by weight and (B) tolylene diisocyanate or diphenylmethane diisocyanate and tris (2-hydroxyethyl)
A resin composition for electrical insulation containing 100 to 1000 parts by weight of a blocked isocyanate resin in which the free isocyanate is blocked with a phenol by a reaction product with isocyanurate, and a resin composition for electrical insulation applied on a conductor and baked. Regarding insulated wires.

Polyester resin (A) used in the present invention
Is obtained by reacting an alcohol with a polybasic acid. It is preferable that the alcohol is reacted in an excess amount with respect to the polybasic acid to cause the hydroxyl group to remain in the polyester resin (A). The residual hydroxyl group reacts with the blocked isocyanate resin during baking to form a urethane bond. From the viewpoint of solderability and heat resistance, the use ratio of alcohol and polybasic acid is from 1.6 to 1.6 in terms of equivalent ratio (alcohol / polybasic acid).
The range of 2.5 is preferable, and the range of 1.6 to 2.0 is more preferable.

Tris (2-hydroxyethyl) isocyanurate is used in an amount of 50 to 90 equivalent%, preferably 55 to 75 equivalent% based on the total alcohol. If the amount of tris (2-hydroxyethyl) isocyanurate used is outside the above range, heat resistance and solderability will be reduced. Examples of alcohol components other than this alcohol include diols such as ethylene glycol and propylene glycol, and triols such as glycerin and trimethylolpropane.

Examples of polybasic acids include terephthalic acid and dimethyl terephthalate, monomethyl terephthalate,
Examples thereof include lower alkyl terephthalates such as diethyl terephthalate. In addition, polybasic acids commonly used for polyester varnish for insulated wires, such as isophthalic acid, adipic acid, phthalic acid, sebacic acid, etc., can be used. The alcohol component and the polybasic acid may be used alone or in combination of two or more.

The polyester resin (A) is synthesized by reacting the alcohol component and the polybasic acid in an organic solvent, preferably in the presence of an esterification catalyst, at a temperature of 170 to 250 ° C. As the esterification catalyst, for example, tetraalkyl titanate such as tetrabutyl titanate,
Lead acetate, dibutyl tin laurate, zinc octenoate, zinc naphthenate and the like are used. As the organic solvent, for example, phenolic solvents such as phenol, cresol, xylenol are used.

The blocked isocyanate resin (B) used in the present invention is obtained by blocking the free isocyanate group of the reaction product of tolylene diisocyanate or diphenylmethane diisocyanate with tris (2-hydroxyethyl) isocyanurate with phenols. can get. Examples of phenols include phenol, cresol, xylenol, and the like.

The mixing ratio of the diisocyanate and tris (2-hydroxyethyl) isocyanurate is such that the hydroxyl group of tris (2-hydroxyethyl) isocyanurate is equivalent to 1 equivalent of isocyanate group of diisocyanate from the viewpoint of heat resistance and solderability. The amount is preferably 0.3 to 0.8 equivalent, and more preferably 0.4 to 0.7 equivalent. Along with the blocked isocyanate resin (B), trimethylolpropane, glycerin, hexanetriol, etc. are added to tolylene diisocyanate or diphenylmethane diisocyanate, and the blocked isocyanate resin is blocked with phenols, for example, Bayer's Dismodu AP Table, Coronate 250 made by Nippon Polyurethane Industry Co., Ltd.
1 and Coronate 2503 may be used in combination.

The resin composition for electrical insulation of the present invention contains 100 parts by weight of the polyester resin (A) and 100 to 1000 parts by weight of the blocked isocyanate resin (B).
When the amount of the blocked isocyanate resin (B) is less than 100 parts by weight, the solderability is deteriorated, and when it exceeds 1000 parts by weight, the heat resistance is deteriorated. In the resin composition of the present invention, an aromatic carboxylic acid or an aliphatic carboxylic acid zinc, lead, a metal salt of lead, manganese, etc., an organometallic compound such as dibutyltin diacetate, dibutyltantin dilaurate, etc. may be added. it can. These organometallic compounds are
It has the effect of improving the wire speed during the production of insulated wires, shortening the curing time, lowering the curing temperature and improving the solderability.

The resin composition of the present invention is usually adjusted in viscosity with an organic solvent, and then applied directly or together with another insulating film on a conductor by a conventional method and baked to form an insulated wire. As the organic solvent, for example, phenol, cresol, xylenol, cellosolves, carbitols and the like are used. A general-purpose solvent such as xylene, toluene or methyl ethyl ketone may be used as a co-solvent.

[0014]

EXAMPLES The present invention will be described in detail below with reference to examples. In addition,% in the following examples means weight%. Example 1 In a four-necked flask equipped with a thermometer, a stirrer and a condenser,
Tris (2-hydroxyethyl) isocyanurate 10
4.4 g (1.2 g equivalent), ethylene glycol 15.
5 g (0.5 g equivalent), dimethyl terephthalate 97.0
g (1.0 g equivalent), 54.2 g of cresol and 0.21 g of tetrabutyl titanate were added, and 2 were added in a nitrogen stream.
The temperature was raised to 00 ° C. and the reaction was carried out for 5 hours. Then, 130.7 g of cresol was added to obtain a polyester resin solution A having a nonvolatile content of 50%. Next, in a four-necked flask equipped with a thermometer, a stirrer, and a condenser, 366 g of xylenol (3.0 g
g equivalent) and diphenylmethane diisocyanate 25
After adding 0 g (2.0 g equivalent) and reacting at 140 ° C. for 1 hour, 104 g (1.2 g equivalent) tris (2-hydroxyethyl) isocyanurate and 0.01 g triethylamine were added and reacted at 125 ° C. for 3 hours. ,afterwards,
183 g of cresol was added to obtain a blocked isocyanate resin solution B having a nonvolatile content of 50%. Polyester resin solution A 100 g, blocked isocyanate resin solution B2
50 g, 87.5 g of cresol and 1.5 g of zinc naphthenate (metal content 6%) were added to obtain an electrically insulating resin composition of the present invention.

Example 2 100 g of the polyester resin solution A obtained in Example 1 was added to the blocked isocyanate resin solution B150 obtained in Example 1.
g, coronate 2503, 50 g, cresol 137.
5 g and 1.5 g of zinc naphthenate (metal content 6%) were added to obtain an electrically insulating resin composition of the present invention.

Comparative Example 1 100 g of the polyester resin solution A obtained in Example 1 was added with 125 g of coronate and 137.5 g of cresol.
And 1.5 g of zinc naphthenate (metal content 6%) was added to obtain a resin composition for electrical insulation. Comparative Example 2 In a four-necked flask equipped with a thermometer, a stirrer and a condenser,
Glycerin 42.9 g (1.4 g equivalent), ethylene glycol 12.8 g (0.4 g equivalent), dimethyl terephthalate 97.0 g (1.0 g equivalent), cresol 57.8.
g and tetrabutyl titanate (0.23 g) were added, and the mixture was heated to 200 ° C. in a nitrogen stream and reacted for 5 hours. Thereafter, 141.6 g of cresol was added to obtain a polyester resin solution a having a nonvolatile content of 50%. To 100 g of this polyester resin solution a, 250 g of the blocked isocyanate resin solution B obtained in Example 1, 87.5 g of cresol and 1.5 g of zinc naphthenate (metal content 6%) were added to obtain a resin composition for electrical insulation. Comparative Example 3 Commercially available heat-resistant urethane varnish for copper copper wire WD-4305
(Manufactured by Hitachi Chemical Co., Ltd.) was used for comparison.

<Test Example> Examples 1 and 2 and Comparative Examples 1 to 1
Using the resin composition for electrical insulation obtained in 3 above, a copper wire having a diameter of 0.4 mm was applied and baked under the baking conditions shown below to produce an insulated electric wire. Baking conditions Baking furnace: Horizontal electric heating furnace (furnace length 3 m) Furnace temperature: Inlet / outlet = 330 ° C./380° C. Linear velocity: 25 m / min Coating method: Die 7 times Draw the insulated wire according to JIS 3003 The results are shown in Table 1. The dielectric breakdown voltage retention rate after heat deterioration was determined by measuring the dielectric breakdown voltage after leaving two twisted wires prepared according to JIS C 3003 in a dryer at 220 ° C. for 168 hours.

[0018]

[Table 1]

From Table 1, the insulated wires obtained by using the resin compositions for electrical insulation of Examples 1 and 2 are more resistant to softening and the dielectric breakdown voltage retention rate after heat deterioration, etc. than those of Comparative Examples. It is shown that it has excellent heat resistance and excellent solderability.

[0020]

EFFECTS OF THE INVENTION According to the resin composition for electrical insulation of the present invention, an insulated wire having a heat resistance of B or more, which is excellent in solderability, softening resistance and dielectric breakdown voltage retention rate after heat deterioration, can be obtained. Obtainable.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Internal reference number FI Technical display location C09D 175/06 PHV 8620-4J H01B 7/34 A 7244-5G

Claims (4)

[Claims] 1. (A) 100 parts by weight of a polyester resin obtained by reacting a polybasic acid with an alcohol in which 50 to 90 equivalent% of all alcohols is tris (2-hydroxyethyl) isocyanurate, and (B) tolylene diene A resin composition for electrical insulation comprising 100 to 1000 parts by weight of a blocked isocyanate resin in which the free isocyanate is blocked with a phenol by a reaction product of isocyanate or diphenylmethane diisocyanate and tris (2-hydroxyethyl) isocyanurate. 2. The resin composition for electrical insulation according to claim 1, wherein the use ratio of total alcohol and polybasic acid is in the range of 1.6 to 2.5 in terms of equivalent ratio (total alcohol / polybasic acid). 3. Tolylene diisocyanate or diphenylmethane so that the hydroxyl group of tris (2-hydroxyethyl) isocyanurate is 0.3 to 0.8 equivalent to 1 equivalent of isocyanate group of tolylene diisocyanate or diphenylmethane diisocyanate. The resin composition for electrical insulation according to claim 1, which is obtained by reacting diisocyanate and tris (2-hydroxyethyl) isocyanurate. 4. An insulated electric wire obtained by coating and baking the resin composition for electrical insulation according to claim 1 on a conductor.