JPH0827244A - Resin composition for electrical insulation and enamel wire - Google Patents

Abstract

PURPOSE:To obtain a resin composition useful for enamel wire, etc., excellent in appearance of coating film even when increasing thickness, solderability, heat resistance and impact resistance, comprising a specific polyester-based resin, a stabilized isocyanate and a prescribed polybasic acid ester. CONSTITUTION:This resin composition comprises (A) a polyester-based resin containing an imide bond in the molecule, (B) a stabilized isocyanate (e.g. a compound obtained from 4,4'-diphenylmethane diisocyanate, an aliphatic polyol and a phenol) and (C) a dibasic acid diester of formula I (R) is a trifunctional 1-4C organic group; R2 and R3 are each a 1-24C alkyl) or a tribasic acid triester of formula II (R4 is R2; R5 is a tetrafunctional 1-4C organic group) as a polybasic acid ester. The content of the component C is preferably 0.05-5.0wt.% based on the components A+B.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a resin composition for electrical insulation, and more specifically, a coating film which has a good appearance even if the coating film is thick and has excellent solderability, heat resistance and thermal shock resistance. The present invention relates to a resin composition for electrical insulation and an enamel wire using the same.

[0002]

2. Description of the Related Art Conventionally, polyurethane wire is known as an enameled wire having solderability, but its heat resistance is classified into Class A to Class E, and is used for applications requiring heat resistance of Class B or higher. It had the drawback that it could not be used. Recently, in order to improve this drawback, a resin composition containing a polyester resin having an imide group in the molecule and a stabilized isocyanate has been proposed and used for B-type insulation. However, this resin composition Although the heat resistance is improved to B type, when the coating is thickly baked, the
There is a defect that foaming, rough skin, etc. occur and the appearance is inferior.
A method of adding a polymer resin such as a nylon resin, a phenoxy resin, an epoxy resin, or a polyester resin to a resin composition in order to improve the appearance of the enamel wire is known,
The addition of these resins to the above resin composition has no effect when the coating is thickly baked, and there is a problem that solderability is poor.

[0003]

DISCLOSURE OF THE INVENTION The present invention solves the above-mentioned problems of the prior art, has an excellent appearance even when a coating is thickened and baked, and can be baked into a fine wire, and has solderability and heat resistance. The present invention provides a resin composition for electrical insulation, which can obtain an enamel wire excellent in heat resistance and thermal shock resistance, and an enamel wire using the same.

[0004]

The present invention provides (a) a polyester resin having an imide bond in the molecule, (b) a stabilized isocyanate, and (c) a general formula (I).

Embedded image A dibasic acid diester represented by the general formula (II)

[Chemical 4] A tribasic acid triester represented by the formula (wherein R ₁ is a trivalent organic group having 1 to 4 carbon atoms, R ₂ and R _{3 in the} above formulas).
And R ₄ is an alkyl group having 1 to 24 carbon atoms, and R ₅ is a tetravalent organic group having 1 to 4 carbon atoms). c) A resin composition for electrical insulation in which the content of at least one dibasic acid diester and tribasic acid triester is 0.05 to 5.0% by weight based on the total amount of the above (a) and (b). The present invention relates to an enamel wire obtained by applying and baking an object and the resin composition for electrical insulation directly or through another insulating material on a conductor.

The polyester resin (a) containing an imide bond in the molecule used in the present invention is obtained by the reaction of an acid component and an alcohol component. Since the imide bond is introduced into the resin, the acid component As a part of the general formula (III)

Embedded image (However, R in the formula means a divalent organic group).

The imidodicarboxylic acid represented by the general formula (III) can be obtained, for example, by reacting 2 mol of trimellitic anhydride with 1 mol of diamine, as shown in JP-B-51-40113. To be Examples of the diamine include 4,4′-diaminodiphenylmethane, m-phenylenediamine, p-phenylenediamine, 1,4-diaminonaphthalene, 4,4′-diaminodiphenyl ether, hexamethylenediamine, diaminodiphenylsulfone and the like. . In the present invention, diisocyanates corresponding to the above diamines may be used in place of these diamines, and the production method thereof is not particularly limited.

From the viewpoint of solderability, heat resistance and thermal shock resistance of the final composition, the amount of the imidodicarboxylic acid represented by the general formula (III) is in the range of 10 to 30 equivalent% of the total acid component. preferable. As the acid component other than the above imidodicarboxylic acid, terephthalic acid or a lower alkyl ester thereof, for example, dimethyl terephthalate, monomethyl terephthalate, terephthalic acid diester and the like are used. Further, compounds commonly used for polyester varnish for enameled wire, for example, isophthalic acid, adipic acid, phthalic acid, sebacic acid and the like can also be used.

The alcohol component used for producing the polyester resin having an imide bond in the molecule is
For example, ethylene glycol, propylene glycol,
Diethylene glycol, neopentyl glycol, 1,
Diols such as 3-butanediol and 1,4-butanediol, triols such as glycerin, trimethylolpropane, hexanetriol, and tris- (2-hydroxyethyl) isocyanurate are used. These acid components and alcohol components may be used alone or in combination of two or more. It is preferable to react all alcohol components in excess with respect to all acid components in an equivalent amount. This is because the hydroxyl group remains in the molecular chain of the polyester resin having an imide bond in the molecule, and this reacts with the stabilized isocyanate during baking to form a urethane bond. Further, the equivalent ratio of the total alcohol component and the total acid component (total alcohol component / total acid component) is preferably 1.3 to 2.5 from the viewpoint of solderability and heat resistance,
1.6-2.4 are more preferable.

The polyester resin (a) having an imide bond in the molecule is synthesized by reacting the acid component and the alcohol component in the presence of an esterification catalyst with heating at a temperature of 170 to 250 ° C. Be seen. Examples of the esterification catalyst used at this time include tetrabutyl titanate, lead acetate, dibutyltin laurate, zinc naphthenate, and the like. The imidodicarboxylic acid may be preliminarily synthesized, and a component that becomes an imidic acid such as diamine or trimellitic anhydride is mixed with other acid components and an alcohol component at the same time and heated to imidize and esterify. May be performed at the same time. In addition, the synthesis of polyester resin having an imide bond in the molecule,
Since the viscosity at the time of synthesis is high, it is preferable to perform it in the coexistence of a phenolic solvent such as phenol, cresol, or xylenol.

The stabilized isocyanate (b) used in the present invention is a compound obtained from 4,4'-diphenylmethane diisocyanate and xylenol (Millionate MS-50 manufactured by Nippon Polyurethane Industry Co., Ltd.), 4,
Compound obtained from 4'-diphenylmethane diisocyanate, aliphatic polyol and phenols (Coronate 2503 manufactured by Nippon Polyurethane Industry Co., Ltd.), compound obtained from tolylene diisocyanate, aliphatic polyol and phenols (Dismodur A manufactured by Bayer)
P stable) and the like. The blending ratio of the polyester resin (a) having an imide bond in the molecule and the stabilizing isocyanate (b) is 100 parts by weight of the polyester resin (a) from the viewpoint of solderability and heat resistance of the enamel wire. On the other hand, stabilized isocyanate (b) 100-100
The range of 0 parts by weight is preferable, and the range of 150 to 500 parts by weight is more preferable.

The dibasic acid diester (c) represented by the general formula (I) used in the present invention can be produced, for example, by heating and mixing a monohydric alcohol with malic acid to effect esterification. it can. As the dibasic acid diester represented by the general formula (I), diethyl malate,
Examples thereof include dibutyl malate, diisopentyl malate, dihexyl malate and the like. The tribasic acid triester (c) represented by the general formula (II) is, for example, citric acid and one or more alcohols selected from aliphatic alcohols, alicyclic alcohols and aromatic alcohols. Is obtained by esterification under ordinary esterification conditions. Examples of the tribasic acid triester represented by the general formula (II) include triethyl citrate. The dibasic acid diester represented by the general formula (I) and the tribasic acid triester represented by the general formula (II) may be used in combination.

The resin composition for electrical insulation of the present invention comprises a dibasic acid diester represented by the general formula (I) and a general formula (II).
The tribasic acid triester represented by the formula (c) is used in an amount of 0.01 to 2. with respect to the total amount of the polyester resin (a) having an imide bond in the molecule and the stabilized isocyanate (b). 0% by weight, preferably 0.05-
It is obtained by blending at a ratio of 1.5% by weight. If the addition amount is less than 0.01% by weight, the appearance of the baking line is not improved, and if it exceeds 2.0% by weight, the heat resistance tends to be lowered. A resin composition for electrical insulation of the present invention comprises a polyester resin (a), a stabilized isocyanate (b), and at least one dibasic acid diester and tribasic acid triester (c) as a solvent. It is manufactured by dissolving and adjusting to an appropriate viscosity. Examples of the solvent used at this time include phenol, cresol, xylenol,
Cellosolves, xylene and the like are used.

The resin composition for electric insulation according to the present invention comprises
You may add an organometallic compound as needed. Examples of the organometallic compound include metal salts such as zinc naphthenate and manganese naphthenate. The resin composition for electrical insulation of the present invention is applied on a conductor directly or via another insulator,
By baking, the appearance is good, and the solderability is
Enamel wire with excellent heat resistance and thermal shock resistance can be obtained.

[0014]

EXAMPLES Next, the present invention will be described in more detail by way of 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, 99 g of 4,4'-diaminodiphenylmethane (1.
0 equivalent), 192 g of trimellitic anhydride (2.0 equivalent), 291 g of dimethyl terephthalate (3.0 equivalent),
Add 93 g (3.0 equivalents) of ethylene glycol, 92 g (3.0 equivalents) of glycerin, 217 g of cresol and 3.8 g of tetrabutyl titanate and add 17 in a nitrogen stream.
The temperature was raised to 0 ° C. and the reaction was performed for 60 minutes. Then, the obtained solution was heated to 210 ° C. and reacted for 3 hours. further,
To this solution, 436 g of cresol was added, and the nonvolatile content was 50%.
A polyester resin solution having an imide bond in the molecule was obtained. Coronate 2503 (stabilized isocyanate compound manufactured by Nippon Polyurethane Industry Co., Ltd.) was added to 100 g of a polyester resin solution having an imide bond in the obtained molecule.
125 g, dihexyl malate 0.175 g, cresol 265 g and zinc naphthenate 1.5 g were added and mixed at room temperature for 30 minutes to obtain a resin composition of the present invention.

Example 2 100 g of the polyester resin solution having an imide bond in the molecule obtained in Example 1 was added to Coronate 25031.
25 g, triethyl citrate 0.875 g, cresol 265 g and zinc naphthenate 1.5 g were added and mixed at room temperature for 30 minutes to obtain a resin composition of the present invention.

Example 3 100 g of the polyester resin solution having an imide bond in the molecule obtained in Example 1 was added to Coronate 25031.
25 g, dihexyl malate 1.75 g, cresol 2
65 g and 1.5 g of zinc naphthenate were added and mixed at room temperature for 30 minutes to obtain a resin composition of the present invention.

Comparative Example 1 100 g of the polyester resin solution having an imide bond in the molecule obtained in Example 1 was added to Coronate 25031.
25 g, 260 g cresol and zinc naphthenate 1.
5 g was added and mixed at room temperature for 30 minutes to obtain a resin composition. Comparative Example 2 A general-purpose polyurethane insulated wire varnish WD-437 (manufactured by Hitachi Chemical Co., Ltd., a polyurethane resin composition using a polyester-based resin having no imide bond in the molecule) is set as Comparative Example 2.

<Test Example> Examples 1 to 3 and Comparative Examples 1 to 1
An enamel wire is produced using the resin composition obtained in 2,
The appearance and characteristics of the enamel wire were examined. (1) Appearance evaluation of enameled wire A copper wire having a diameter of 0.07 mm was baked under the following conditions while changing the coating thickness, and the appearance was visually observed. Table 1 shows the results. The baking conditions are as follows. Baking furnace: Horizontal furnace Furnace temperature: Inlet / outlet = 330 ° C / 380 ° C Linear velocity: 240m / min Coating method: Felt 7 times drawing

[0019]

[Table 1] From the results of Table 1, the resin composition of the present invention is
It is shown that the appearance is better than that of

(2) Evaluation of characteristics of enameled wire Under the same conditions as in (1), a copper wire having a diameter of 0.4 mm was baked and various characteristics were evaluated. The results are shown in Table 2. The test items in Table 2 were evaluated according to JIS C 3003 5-19. Regarding the breakdown voltage after heat deterioration, see JIS C.
Twisted wire manufactured according to 3003
After leaving it in the constant temperature bath of No. 168 for 168 hours, the dielectric breakdown voltage was measured.

[0021]

[Table 2] From the results in Table 2, when the resin composition of the present invention is used, thermal shock resistance, retention of the dielectric breakdown voltage after thermal deterioration, and retention in comparison with the case of the conventional general-purpose polyurethane insulated wire (Comparative Example 2) It is shown that the softening resistance is excellent and no deterioration in properties is observed as compared with the conventional heat-resistant urethane wire of Comparative Example 1.

[0022]

EFFECTS OF THE INVENTION According to the resin composition for electrical insulation of the present invention, the appearance is good even if the coating is thickened, the heat resistance and softening resistance are excellent, the solderability is excellent, and the thermal shock resistance is also excellent. Excellent enamel wire can be manufactured.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical display location C08L 79/08 LRB C09D 5/25 PQY H01B 3/30 M

Claims (3)

[Claims] 1. A polyester resin having (a) an imide bond in the molecule, (b) a stabilized isocyanate, and (c) a general formula (I): A dibasic acid diester represented by the general formula (II) A tribasic acid triester represented by the formula (wherein R ₁ is a trivalent organic group having 1 to 4 carbon atoms, R ₂ and R _{3 in the} above formulas).
And R ₄ is an alkyl group having 1 to 24 carbon atoms, and R ₅ is a tetravalent organic group having 1 to 4 carbon atoms). 2. The content of at least one of the dibasic acid diester and the tribasic acid triester (c) is 0.05 to 5.0 with respect to the total amount of the above (a) and (b).
The resin composition for electrical insulation according to claim 1, wherein the resin composition is used as a weight percentage. 3. An enameled wire obtained by applying and baking the resin composition for electrical insulation according to claim 1 or 2 on a conductor directly or via another insulator.