JP2012171979A - Resin composition for electric insulation, and enamel wire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a resin composition for electric insulation, having excellent flexibility, and to provide an enamel wire having excellent flexibility made by using the resin composition.SOLUTION: The resin composition for the electric insulation includes a polyamide-imide resin obtained by reacting (A) a polycarboxylic acid component containing a tri- or poly-basic polycarboxylic acid anhydride having an acid anhydride group and a carboxy group, (B) an imide dicarboxylic acid having a (m-phenylenediisopropylidene) structure and represented by general formula (1), and (C) an aromatic polyisocyanate in a basic polar solvent. The enamel wire is obtained by using the resin composition.

Description

  The present invention relates to a resin composition for electrical insulation and an enameled wire using the same.

Polyamideimide resins are excellent in heat resistance, chemical resistance, and solvent resistance, and are therefore used as various paints such as enameled wire varnishes.
In recent years, electrical manufacturers that use enameled wires have introduced automatic high-speed winding machines to streamline the manufacturing process of the equipment, but the enameled wires are subject to friction, impact, etc. during the winding process to insulate the enameled wires. There is a problem in that the mechanical defect is caused in the layer, and a short circuit, a ground failure, and the like occur to increase the defective rate of the product. Therefore, an enameled wire with little mechanical damage is desired.

  Conventional polyamide-imide wire is superior in mechanical strength and heat resistance to other polyesters, polyester-imide wires, etc., so when working under particularly severe conditions, for example, 4,4'-diphenylmethane diisocyanate and trimellitic anhydride The polyamideimide resin obtained by the reaction with is applied in a single layer or multilayer structure (see Patent Documents 1 and 2).

  However, the speed of winding machines and the complexity of winding processes have further increased year by year, and severe stress such as elongation, wear, and bending has been applied to enameled wires, and the high flexibility of the coating has become particularly important. It has come to be required.

  As a means for improving the flexibility of the polyamide-imide varnish film, there is a method of using a long-chain aliphatic acid as a monomer, but there is a problem that the heat resistance of the enameled wire film decreases when this method is used. .

Japanese Patent Publication No. 44-019274 Japanese Examined Patent Publication No. 45-027611

  The present invention provides a polyamide-imide electrical insulating resin composition excellent in flexibility and an enameled wire using the same, while maintaining various properties such as mechanical properties, heat resistance and electrical insulation properties of the enamel wires. It is to provide.

・・・（１）
で表される（ｍ−フェニレンジイソプロピリデン）構造を有するイミドジカルボン酸及び（Ｃ）芳香族ポリイソシアネートを塩基性極性溶媒中で反応させて得られるポリアミドイミド樹脂を含む電気絶縁用樹脂組成物。
２． 反応に用いられる（Ａ）成分と（Ｂ）成分との配合割合｛（Ｂ）／（Ａ）｝が、当量比で０．０１／０．９９〜０．７０／０．３０である項１記載の電気絶縁用樹脂組成物。
３． 反応に用いられるイソシアネート成分とポリカルボン酸成分との配合割合｛（Ｃ）／〔（Ａ）＋（Ｂ）〕｝が当量比で０．８〜１．４である項１又は項２記載の電気絶縁用樹脂組成物。
４． ポリアミドイミド樹脂が、数平均分子量１０，０００〜５０，０００のものである項１〜３いずれかに記載の電気絶縁用樹脂組成物。
５． 項１〜４のいずれかに記載の電気絶縁用樹脂組成物を導体上に塗布し、焼付けてなるエナメル線。 The present invention relates to the following.
1. (A) a polycarboxylic acid component essentially comprising a tricarboxylic or higher polycarboxylic acid anhydride having an acid anhydride group and a carboxyl group, (B) a general formula (1)

... (1)
The resin composition for electrical insulation containing the polyamidoimide resin obtained by making the imide dicarboxylic acid which has (m-phenylene diisopropylidene) structure represented by these, and (C) aromatic polyisocyanate react in a basic polar solvent.
2. Item 1 wherein the blending ratio {(B) / (A)} of the component (A) and the component (B) used in the reaction is 0.01 / 0.99 to 0.70 / 0.30 in terms of equivalent ratio. The resin composition for electrical insulation as described.
3. Item 1 or Item 2 wherein the blending ratio {(C) / [(A) + (B)]} of the isocyanate component and polycarboxylic acid component used in the reaction is 0.8 to 1.4 in terms of equivalent ratio. Resin composition for electrical insulation.
4). Item 4. The resin composition for electrical insulation according to any one of Items 1 to 3, wherein the polyamideimide resin has a number average molecular weight of 10,000 to 50,000.
5. Item 5. An enameled wire obtained by applying and baking a resin composition for electrical insulation according to any one of items 1 to 4 on a conductor.

If the oil composition for electrical insulation according to the present invention is used, it is possible to form a coating film with good flexibility, and it is useful for insulating films and protective coatings on various substrates, especially for enameled wires and the like. It can be suitably used for severe winding, processing, and assembly work in recent years.
Moreover, the enameled wire of the present invention is excellent in flexibility.

The polycarboxylic acid component (A) used in the production of the polyamide-imide resin in the present invention contains, in one molecule, [an acid anhydride group that reacts with an isocyanate group to form an imide bond] and [isocyanate group]. Or a mixture thereof having a total of two or more carboxyl groups that form an amide bond by reacting with.
Examples of the trivalent or higher polycarboxylic acid anhydride having an acid anhydride group and a carboxyl group include aromatic tricarboxylic acid anhydrides represented by the general formulas (2) and (3). In view of heat resistance, cost, etc., trimellitic anhydride is particularly preferable.

(However, in both formulas, R ′ represents hydrogen, an alkyl group having 1 to 10 carbon atoms, or a phenyl group, and Y represents —CH ₂ —, —CO—, —SO ₂ —, or —O—.)

In addition to these, as the polycarboxylic acid component of component (A), if necessary, tetracarboxylic dianhydride {pyromellitic dianhydride, 3,3′-4,4′-benzophenone tetracarboxylic Acid dianhydride, 3; 3′-4,4′-biphenyltetracarboxylic dianhydride, 2,2′-3,3′-biphenyltetracarboxylic dianhydride, 2,3,3 ′, 4 ′ -Biphenyltetracarboxylic dianhydride 3,3 ', 4,4'-diphenylsulfonetetracarboxylic dianhydride, ethylene glycol bisandhydrotrimellitate, 2,2-bis (2,5-dicarboxyl Phenyl) propane dianhydride, 1,1-bis (2,3-dicarboxyphenyl) ethanoic dianhydride, 1,1-bis (3,4-dicarboxyphenyl) sulfone dianhydride, 1,2,5, 6-naphthale Tetracarboxylic dianhydride, 2,3,5,6-pyridinetetracarboxylic dianhydride, 1,4,5,8-naphthalenetetracarboxylic dianhydride, 3,4,9,10-perylenetetracarboxylic Acid dianhydride, 4,4′-sulfonyldiphthalic dianhydride, m-terphenyl-3,3 ′, 4,4′-tetracarboxylic dianhydride, 4,4′-oxydiphthalic dianhydride 1,1,1,3,3,3-hexafluoro-2,2-bis (2,3- or 3,4-dicarboxyphenyl) propane dianhydride, 1,3-bis (3,4- Dicarboxylphenyl) -1,1,3,3-tetramethyldisiloxane dianhydride, butanetetracarboxylic dianhydride, bicyclo- [2,2,2] -oct-7-ene-2: 3: 5 : 6-tetracaribonic acid dianhydride, etc.}, aliphatic dicarboxylic acid (Succinic acid, glutaric acid, adipic acid, azelaic acid, suberic acid, sebacic acid, decanedioic acid, dodecanedioic acid, dimer acid, etc.), aromatic dicarboxylic acid (isophthalic acid, terephthalic acid, phthalic acid, naphthalenedicarboxylic acid, Oxydibenzoic acid etc.) can be used in combination. In addition, derivatives of these polycarboxylic acid components can also be used.
The amount of these acids and acid anhydrides used is preferably 50 equivalent% or less of the total acid component.

  In the present invention, the imide dicarboxylic acid represented by (1) used as the component (B) is 4,4 ′-(m-phenylenediisopropylidene) dianiline represented by the following (4), trimellitic anhydride and none. It can be obtained by reacting in a solvent or an organic solvent.

・・・・・（４）

(4)

The mixing ratio of trimellitic anhydride and 4,4 ′-(m-phenylenediisopropylidene) dianiline component is preferably such that the acid group / amine group is 1.01 or more in terms of equivalent ratio. It is more preferable to set it to -2.5, and it is still more preferable to set it to 1.9-2.1.
The reaction can be easily performed without solvent or in the presence of an organic solvent.
Examples of organic solvents that can be used include ketone solvents (methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, etc.) ester solvents (ethyl acetate, butyl acetate, γ-butyrolactone, etc.), ether solvents (diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, etc.) ), Cellosolve solvents (butyl cellosolve acetate, ethyl cellosolve acetate, methyl cellosolve acetate, etc.), aromatic hydrocarbon solvents (toluene, xylene, p-cymene, etc.), tetrahydrofuran, dioxane, N-methyl-2-pyrrolidone, N, N-dimethylformamide, N, N-dimethylacetamide, dimethyl sulfoxide and the like can be mentioned.

  There is no restriction | limiting in particular as an aromatic polyisocyanate compound of (C) component in this invention, For example, there exists a diisocyanate compound represented by following General formula (5).

［ただし、式中、Ｘは、炭素数１〜１８のアルキレン基又はフェニレン基、トリレン基等のアリーレン基（これはメチル基等の炭素数１〜４の低級アルキル基を置換基として有していてもよく、炭素数１〜１８のアルキレン基を有していてもよい）を示す］。

[Wherein X is an alkylene group having 1 to 18 carbon atoms or an arylene group such as a phenylene group or a tolylene group (this has a lower alkyl group having 1 to 4 carbon atoms such as a methyl group as a substituent). And may have an alkylene group having 1 to 18 carbon atoms)].

  Examples of the diisocyanate compound represented by the general formula (5) include diphenylmethane-2,4′-diisocyanate, 3,2′- or 3,3′- or 4,2′- or 4,3′-. Or 5,2'- or 5,3'- or 6,2'- or 6,3'-dimethyldiphenylmethane-2,4'-diisocyanate, 3,2'- or 3,3'- or 4,2 ' -Or 4,3'- or 5,2'- or 5,3'- or 6,2'- or 6,3'-diethyldiphenylmethane-2,4'-diisocyanate, 3,2'- or 3,3 '-Or 4,2'- or 4,3'- or 5,2'- or 5,3'- or 6,2'- or 6,3'-dimethoxydiphenylmethane-2,4' diisocyanate, diphenylmethane-4 , 4'-diisocyanate, benzophenone-4 4′-diisocyanate, diphenylsulfone-4,4′-diisocyanate, diphenylsulfone-4,4′-diisocyanate, tolylene-2,4-diisocyanate, tolylene-2,6-diisocyanate, m-xylylene diisocyanate, p-xylylene Various conventionally known diisocyanate compounds such as diisocyanate, naphthalene-2,6-diisocyanate, 4,4 ′-{2,2bis (4-phenoxyphenyl) propane} diisocyanate may be mentioned. These may be used alone or in admixture of two or more. Among the above polyisocyanate compounds, diphenylmethane-4,4'-diisocyanate is most preferably used in the present invention from the viewpoint of heat resistance and mechanical properties of the film.

In addition, aliphatic such as hexamethylene diisocyanate, 2,2,4-trimethylhexamethylene diisocyanate, isophorone diisocyanate, 4,4′-dicyclohexylmethane diisocyanate, transcyclohexane-1,4-diisocyanate, hydrogenated m-xylylene diisocyanate, or the like Alicyclic polyisocyanates may be used. Furthermore, you may use a polyisocyanate compound more than trifunctional.
Further, these polyisocyanate compounds may be stabilized with a blocking agent necessary for avoiding changes over time.

In the present invention, the mixing ratio of the imide dicarboxylic acid represented by the general formula (1) of the component (B) and the polycarboxylic acid component of the component (A) is an equivalent ratio of {(B) component / (A) component}. 0.01 / 0.99 to 0.70 / 0.30 is preferable, 0.1 / 0.9 to 0.5 / 0.5 is more preferable, and 0.2 / 0.8 It is especially preferable to set it to -0.4 / 0.6.
If the equivalent ratio is less than 0.01 / 0.99, there is no effect of improving the flexibility, and if it exceeds 0.70 / 0.30, the heat resistance of the film may be significantly reduced.

Further, the blending ratio of the isocyanate component and the acid component is preferably such that {(C) component / (B) component + (A) component} is 0.8 to 1.4 in terms of equivalent ratio, 0.9 -1.3 is more preferable, and 0.9-1.2 is particularly preferable.
If this ratio is less than 0.8, it is difficult to increase the molecular weight of the polyamideimide resin, and if it exceeds 1.4, the flexibility may be significantly reduced.

  The synthesis of the polyamideimide resin using each component is performed in an organic solvent, and a polar solvent is preferably used as the organic solvent from the viewpoint of solubility. Specifically, N-methyl-2-pyrrolidone, N, N-dimethylacetamide, N, N-diethylacetamide, N, N-dimethylformamide, N, N-diethylformamide, dimethylsulfoxide, hexamethylphosphoramide, Although tetramethylene sulfone is mentioned, it can be used alone or in combination. From the viewpoint of economy and ease of polymerization, it is preferable to use N-methyl-2-pyrrolidone or N, N-dimethylacetamide. Moreover, although there is no restriction | limiting in particular in the usage-amount, it is 100 to 100 weight part with respect to 100 weight part of total amounts of the said polycarboxylic acid, 4,4'- (m- phenylene diisopropylidene) imide dicarboxylic acid, and aromatic polyisocyanate. The amount is preferably 900 parts by weight, more preferably 125 to 600, and particularly preferably 150 to 400.

The number average molecular weight of the polyamideimide resin thus obtained is preferably 10,000 to 50,000, more preferably 15,000 to 40,000, and 20,000 to 35,000. It is particularly preferred that
If the number average molecular weight is less than 10,000, various properties such as heat resistance and mechanical properties of the film tend to be lowered. If the number average molecular weight is more than 50,000, it is dissolved in a solvent so as to have an appropriate concentration as a paint. The viscosity tends to increase and the workability during painting tends to be inferior.

  The number average molecular weight of the polyamideimide resin is measured by sampling the reaction solution at the time of synthesis, using a standard polystyrene calibration curve by gel permeation chromatography (GPC), and performing synthesis until the target number average molecular weight is reached. By continuing, it can be adjusted to a desired range.

The resin composition for electrical insulation of the present invention is used as a coating material in which 10 to 50% by weight, preferably 20 to 40% by weight, of this polyamideimide resin is dissolved in a solvent. Examples of organic solvents that can be used at this time include ketone solvents (methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, etc.) ester solvents (ethyl acetate, butyl acetate, γ-butyrolactone, etc.), ether solvents (diethylene glycol dimethyl ether, triethylene glycol). Dimethyl ether, etc.), cellosolve solvents (butyl cellosolve acetate, ethyl cellosolve acetate, methyl cellosolve acetate, etc.), aromatic hydrocarbon solvents (toluene, xylene, p-cymene, etc.), tetrahydrofuran, dioxane, N-methyl-2-pyrrolidone, N, N-dimethylformamide, N, N-diethylformamide, N, N-dimethylacetamide, N, N-diethylacetamide, dimethyl sulfoxide, hexamethylphos Ruamido, and organic solvents such as tetramethylene sulfone.
In the resin composition for electrical insulation of the present invention, the above-mentioned polyamideimide resin synthesis solution can be used as it is, the solid content is appropriately prepared, and the solid content can also be prepared with the organic solvent. Furthermore, after synthesis, the polyamideimide resin can be separated and then dissolved in the organic solvent.

  The resin composition for electrical insulation of the present invention can be made into an enameled wire with excellent flexibility by applying and baking on a conductor such as a copper wire. There is no restriction | limiting in particular in the manufacturing method of an enamel wire except using the resin composition for electrical insulation of this invention, It can follow a conventional method. For example, the process of applying the resin composition for electrical insulation of the present invention on a conductor and heating and baking at 350 to 550 ° C., preferably 400 to 500 ° C. for 1 to 5 minutes, preferably 2 to 4 minutes, is performed a plurality of times. A method of repeatedly forming a film having a desired thickness on a conductor is mentioned. Although the thickness of the film finally formed is not particularly limited, it is usually preferably 0.01 to 0.08 mm, and more preferably 0.02 to 0.06 mm. In addition, the conductor is not limited to a copper wire, and an aluminum wire or the like may be used, and the cross-sectional shape may be circular or flat. The structure of the enameled wire film may be a single layer of the resin composition for electrical insulation of the present invention, or a two-layer structure in which the resin composition for electrical insulation of the present invention is applied to an upper layer coated with polyesterimide or the like, or three or more layers The film configuration may be as follows. The enameled wire of the present invention thus obtained does not deteriorate various properties such as flexibility and heat resistance.

  EXAMPLES Next, although an Example demonstrates this invention further in detail, this invention is not limited to these. In the examples, “%” means “% by weight” unless otherwise specified.

4,4 '-(m-phenylenediisopropylidene) dianiline 34.5 g (0.1 mol), trimellitic anhydride 38.4 g (0.2 mol) and N-methyl-2-pyrrolidone 109.4 g were heated. A flask equipped with a meter, a stirrer, and a cooling tube was charged, and the mixture was gradually heated up to 100 ° C. over about 1 hour in a dried nitrogen stream, and kept at 100 ° C. for 1 hour. , (B) component imidodicarboxylic acid (0.1 mol) was obtained.
Further, in this reaction solution, 172.9 g (0.90 mol) of trimellitic anhydride as component (A) and 254.0 g (1.015 mol) of diphenylmethane-4,4′-diisocyanate as component (C) and N— Methyl-2-pyrrolidone (640.3 g) was charged, and the temperature was raised gradually to 140 ° C. over about 4 hours, paying attention to the sudden bubbling of carbon dioxide gas generated by the reaction. A solution of polyamideimide resin having a molecular weight of 27100 was obtained.

The blending ratios of component (A), component (B), and component (C) used in this reaction are as follows in terms of equivalent ratio.
{(B) / (A)} = 0.10 / 0.90
{(C) / [(A) + (B)]} = 1.015
The obtained solution was diluted with N-methyl-2-pyrrolidone to obtain a polyamideimide resin solution (resin composition for electrical insulation) having a resin concentration of 30% by weight.

A temperature of 103.4 g (0.3 mol) of 4,4 ′-(m-phenylenediisopropylidene) dianiline, 115.3 g (0.6 mol) of trimellitic anhydride and 328.1 g of N-methyl-2-pyrrolidone A flask equipped with a meter, a stirrer, and a cooling tube was charged, and the mixture was gradually heated up to 100 ° C. over about 1 hour in a dried nitrogen stream, and kept at 100 ° C. for 1 hour. , (B) component imidodicarboxylic acid (0.3 mol) was obtained.
Furthermore, 134.5 g (0.7 mol) of trimellitic anhydride as component (A) and 256.5 g (1.025 mol) of diphenylmethane-4,4′-diisocyanate as component (C) and N— Methyl-2-pyrrolidone (804.2 g) was charged, and the temperature was raised gradually to 140 ° C. over about 4 hours, paying attention to the sudden bubbling of carbon dioxide gas generated by the reaction. A solution of polyamideimide resin having a molecular weight of 31700 was obtained.

The blending ratios of component (A), component (B), and component (C) used in this reaction are as follows in terms of equivalent ratio.
{(B) / (A)} = 0.30 / 0.70
{(C) / [(A) + (B)]} = 1.025
The obtained solution was diluted with N-methyl-2-pyrrolidone to obtain a polyamideimide resin solution (resin composition for electrical insulation) having a resin concentration of 30% by weight.

A temperature of 68.9 g (0.2 mol) of 4,4 '-(m-phenylenediisopropylidene) dianiline and 76.9 g (0.4 mol) of trimellitic anhydride and 218.7 g of N-methyl-2-pyrrolidone A flask equipped with a meter, a stirrer, and a cooling tube was charged, and the mixture was gradually heated up to 100 ° C. over about 1 hour in a dried nitrogen stream, and kept at 100 ° C. for 1 hour. , (B) component imidodicarboxylic acid (0.2 mol) was obtained.
Furthermore, 153.7 g (0.8 mol) of trimellitic anhydride as component (A) and 202.2 g (0.808 mol) of diphenylmethane-4,4′-diisocyanate as component (C) were added to this reaction solution. , 3'-dimethylbiphenyl-4,4'-diisocyanate 53.4g (0.4mol) and N-methyl-2-pyrrolidone 812.2g, pay attention to the sudden foaming of carbon dioxide generated by the reaction However, the temperature was raised gradually over about 4 hours, and the temperature was raised to 145 ° C., followed by reaction for 10 hours to obtain a polyamideimide resin solution having a number average molecular weight of 32,000.

The blending ratios of component (A), component (B), and component (C) used in this reaction are as follows in terms of equivalent ratio.
{(B) / (A)} = 0.20 / 0.80
{(C) / [(A) + (B)]} = 1.01
The obtained solution was diluted with N-methyl-2-pyrrolidone to obtain a polyamideimide resin solution (resin composition for electrical insulation) having a resin concentration of 30% by weight.

(Comparative Example 1)
Add 192.1 g (1.0 mol) of trimellitic anhydride, 262.8 g (1.05 mol) of 4,4'-diphenylmethane diisocyanate, and 682.4 g of N-methyl-2-pyrrolidone to a thermometer, stirrer, and condenser. The mixture was placed in a equipped flask, and the mixture was gradually heated to 140 ° C. over about 5 hours in a dry nitrogen stream while paying attention to the sudden foaming of carbon dioxide gas generated by the reaction. For 7 hours. As a result, a solution of polyamideimide resin having a number average molecular weight of 26000 was obtained.
This solution was diluted with N-methyl-2-pyrrolidone to obtain a polyamideimide resin solution having a resin concentration of 30%.

(Comparative Example 2)
60.1 g (0.3 mol) of 4,4′-diaminodiphenyl ether, 115.3 g (0.6 mol) of trimellitic anhydride and 263.1 g of N-methyl-2-pyrrolidone were thermometer, stirrer and condenser. The mixture was charged into a flask equipped with this mixture, and the mixture was gradually heated in a nitrogen stream for about 1 hour, heated to 100 ° C., kept at 100 ° C. for 1 hour, and imidodicarboxylic acid (0. 3 mol) was obtained.
Furthermore, 134.5 g (0.70 mol) of trimellitic anhydride, 255.3 g (1.02 mol) of diphenylmethane-4,4′-diisocyanate and 584.7 g of N-methyl-2-pyrrolidone were charged into this reaction solution. The polyamide imide having a number average molecular weight of 27000 is obtained by gradually raising the temperature to about 140 ° C. over about 6 hours while paying attention to the sudden foaming of carbon dioxide gas generated by the reaction, and then reacting at this temperature for 7 hours. A resin solution was obtained.
The obtained solution was diluted with N-methyl-2-pyrrolidone to obtain a polyamideimide resin solution having a resin concentration of 30% by weight.

(Comparative Example 3)
Trimellitic anhydride 153.7 g (0.8 mol), dodecanedioic acid 46.1 g (0.2 mol), 4,4'-diphenylmethane diisocyanate 262.8 g (1.05 mol), N-methyl-2- 682.4 g of pyrrolidone was put into a flask equipped with a thermometer, a stirrer and a condenser, and this mixture was gradually dried over a period of about 6 hours in a dry nitrogen stream while paying attention to the sudden foaming of carbon dioxide generated by the reaction. The temperature was raised to 140 ° C., and the mixture was kept at 140 ° C. for 7 hours to obtain a polyamideimide resin solution having a number average molecular weight of 26000.
This solution was diluted with N-methyl-2-pyrrolidone to obtain a polyamideimide resin solution having a resin concentration of 30%.

(Test example)
The polyamideimide resin solutions obtained in Examples 1 to 3 and Comparative Examples 1 to 3 were applied to a copper wire having a diameter of 1.0 mm in accordance with the following baking conditions, and baked at a wire speed of 16 m / min to produce an enameled wire. .
[Coating / baking conditions]
Baking furnace: Hot air type furnace (furnace length 5.5m)
Furnace temperature: Inlet / Outlet = 320 ° C / 430 ° C
Coating method: The procedure of passing the enamel wire through which the resin composition has passed through a die and passing through a baking furnace is performed 8 times. The diameters of the dies from the first to the eighth time were changed to 1.05 mm, 1.06 mm, 1.07 mm, 1.08 mm, 1.09 mm, 1.10 mm, 1.11 mm, and 1.12 mm.
Further, the properties (flexibility, unidirectional wear, dielectric breakdown voltage, softening resistance, thermal shock resistance) of the enameled wire obtained were measured according to JIS C 3003. The results are shown in Table 1.

  From the results shown in Table 1, the enameled wire coatings produced using the polyamideimide resin solutions obtained in Examples 1 to 3 were produced using the polyamideimide resin solutions obtained in Comparative Examples 1 to 3. It can be seen that the film is excellent in flexibility as compared with the coated film of enameled wire, and the softening resistance and unidirectional wear are almost equally good.

Claims (5)

(A) a polycarboxylic acid component essentially comprising a tricarboxylic or higher polycarboxylic acid anhydride having an acid anhydride group and a carboxyl group, (B) a general formula (1)

... (1)
The resin composition for electrical insulation containing the polyamidoimide resin obtained by making the imide dicarboxylic acid which has (m-phenylene diisopropylidene) structure represented by these, and (C) aromatic polyisocyanate react in a basic polar solvent.   The blending ratio {(B) / (A)} of the component (A) and the component (B) used in the reaction is 0.01 / 0.99 to 0.70 / 0.30 in an equivalent ratio. The resin composition for electrical insulation according to 1.   The blending ratio {(C) / [(A) + (B)]} of the isocyanate component and the polycarboxylic acid component used for the reaction is 0.8 to 1.4 in terms of an equivalent ratio. Resin composition for electrical insulation.   The resin composition for electrical insulation according to any one of claims 1 to 3, wherein the polyamideimide resin has a number average molecular weight of 10,000 to 50,000.   An enameled wire obtained by applying and baking the resin composition for electrical insulation according to any one of claims 1 to 4 on a conductor.