JPS6213768B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to an insulated wire with excellent mechanical windability and heat resistance. Insulated wires coated with polyimide resin have excellent heat resistance and are often used as enameled wires in the 220°C class, but they have the disadvantage that the mechanical strength of the coating is poor. The present invention aims to improve the mechanical strength of polyimide resin-coated insulated wires and to provide inexpensive insulated wires. The gist of the present invention is to coat and bake a polyimide resin layer as an interpolation directly above the conductor, and on the top layer, as an outer layer, 1.00 equivalent of polycarboxylic acid containing an acid anhydride group and polyisocyanate containing an isocyanurate ring are coated. 100 weight of cresol-soluble polyamideimide resin obtained by reacting in a cresol solvent with 0.01 to 0.30 equivalent, the sum of the equivalents of aromatic diisocyanate and isocyanurate ring-containing polyisocyanate to 0.8 to 1.50 equivalent, and lactam to 0.30 to 0.90 equivalent. an insulated wire, characterized in that it is made by coating and baking a resin composition in which 0.10 to 15 parts by weight of an amino resin and a phenolic resin are added to each part of the inner layer to a thickness of 0.5 to 20 times that of the inner layer. It is in. The isocyanurate ring-containing polyisocyanate, which is the raw material for the polyamide-imide resin used in the present invention, is obtained by trimerizing polyisocyanate compounds, and this reaction is carried out in the presence of a solvent that does not react with isocyanate groups. It is desirable to use a trimerization catalyst of a polyisocyanate compound in order to carry out the reaction without adding a component that reacts with isocyanate groups such as, and to proceed efficiently with the reaction. Examples of solvents include aliphatic and aromatic hydrocarbons, halogenated aromatic hydrocarbons, ester-based, ketone-based, ether-based, and ethylene glycol monoalkyl monoacetate-based solvents as long as they dissolve the polyisocyanate compound as a raw material. , dimethyl sulfoxide, etc. Trimerization catalysts for polyisocyanate compounds include alkali metal acetates, metal salts and organometallic compounds such as iron, magnesium, nickel, zinc, tin, lead, vanadium, and titanium, N-methylmorpholine, 1,8-diazabicyclo(5, 4,
0) Mannitz bases of phenols such as undecane-7,2-(dimethylaminomethyl)-4,6-dimethylphenol, tertiary amines such as 2-dimethylaminoethanol, etc. can be used, and there are no particular limitations. The reaction temperature for trimerizing the polyisocyanate compound is, for example, in the range of 50 to 160°C. The raw material for the isocyanurate ring-containing polyisocyanate may be any aliphatic, alicyclic, or aromatic diisocyanate compound, but aromatic diisocyanates, especially 4,4'-diphenylmethane diisocyanate, tolylene diisocyanate, and xylylene diisocyanate , 4,4'-diphenyl ether diisocyanate and the like are preferred. In terms of heat resistance and flexibility, the isocyanurate ring-containing polyisocyanate preferably has a residual isocyanate group content in the range of 10 to 70% (the isocyanate group content in the raw material isocyanate is 100% to 70%).
). It is preferable to use the isocyanurate ring-containing polyisocyanate in an amount of 0.01 to 0.30 equivalents based on the total isocyanate components in terms of heat resistance and flexibility.
Lactam, which is an important raw material for cresol solvent solubilization, can generally be anything that reacts with isocyanate groups or acid anhydride groups in cresol solvents and is soluble in cresol solvents. , considering solubility, reactivity and price, ε
-Caprolactam is preferred. The amount of lactam to be used is preferably 0.30 to 0.90 equivalents of the total isocyanate equivalents (considering ε-caprolactam to be difunctional) in terms of heat resistance, flexibility and solubility. Preferred aromatic diisocyanates include 4,4'-diphenylmethane diisocyanate, 4,4'-diphenyl ether diisocyanate, tolylene diisocyanate, and xylylene diisocyanate. As a polycarboxylic acid having an acid anhydride group,
Trimellitic anhydride is preferred in terms of heat resistance and cost. From the viewpoint of heat resistance, it is preferable to select the amounts of the isocyanate component and acid component so that the ratio of isocyanate groups to carboxyl groups and acid anhydride groups is 1.5 to 0.8. In order to obtain a resin with a high molecular weight that is preferable in view of the characteristics of an insulated wire, it is particularly preferable that the ratio of isocyanate groups to carboxyl groups and acid anhydride groups is around 1.0. As the cresol solvent, in addition to cresol, phenol, xynol, etc. can be used, and a mixed solvent may also be used. Synthesis is carried out by charging all isocyanate components, lactam and cresol solvent and heating at 160 to 190℃ for 1 to 3 hours.
After reacting for an hour, an acid anhydride group-containing polycarboxylic acid is added, and the reaction is continued at 200 to 220°C for 10 to 20 hours. The thus obtained polyamide-imide resin has particularly good properties as an insulated wire if it has a reduced specific viscosity of 0.15 or more when measured in dimethylformamide. This polyamide-imide resin is then diluted with a cresol solvent to a resin content of 20 to 40% by weight and used as a varnish for insulated wires. The polyamide-imide resin in the present invention forms an enamel film with excellent heat resistance, mechanical properties, and fluorocarbon resistance even when used alone, but the phenol formaldehyde resin has poor hardenability and workability during high-speed baking.
Significant improvement can be achieved by adding one or more secondary resins such as alkoxy-modified amino resins, epoxy resins, polyisocyanate resins, and phenoxy resins. The amount of the secondary resin added is 0.1 to 30 parts by weight per 100 parts by weight of the polyamide-imide resin, and if this range is exceeded, the flexibility of the enameled wire will decrease. In particular, amino resin and phenol resin are added to 100 parts by weight of polyamide-imide resin, respectively.
When a resin composition containing 0.1 to 15 parts by weight is used, an insulating film with excellent appearance and flexibility can be obtained. Polyimide resins used in the present invention include, but are not limited to, Trenice #2000, #3000 (manufactured by Toray Industries, Inc.) and Pyre-ML varnish (manufactured by Du-Pont, USA). In addition, in the present invention, when the outer layer film thickness is 1, the inner layer film thickness is set to 0.5 to 20.When the inner layer film thickness is 0.5 or less, mechanical strength (wear resistance) improves, but heat resistance The decline in sex is greater and 20
This is because in the above cases, although heat resistance is good, sufficient mechanical strength cannot be obtained. In order to maintain a balance between mechanical strength and heat resistance, it is preferable that the inner layer has a thickness of 2 to 6 when the outer layer has a thickness of 1. Hereinafter, a description will be given while comparing specific examples of the present invention and comparative examples. Comparative Example 1 An enamelled wire was obtained by applying and baking TRENICE #2000 varnish onto a 1.0 mmφ conductor. Comparative Example 2 (1) Synthesis components of aromatic diisocyanate trimer Grams Tolylene diisocyanate 600 Xylene 600 2-dimethylaminoethanol (catalyst) 1.8 Place the above ingredients in a four-necked flask equipped with a thermometer and a stirrer, The temperature was raised to 140℃ in a nitrogen stream,
At the same temperature, the content of isocyanate groups (initial concentration
48% by weight) was reduced to 25% by weight. (2) Synthesis of polyamideimide resin

[Table] The above ingredients except trimellitic anhydride were placed in a four-necked flask equipped with a thermometer, stirrer, and fractionating tube, and the temperature was raised to 180°C in a nitrogen stream.
Perform the reaction for minutes. Next, trimellitic anhydride was added, the temperature was raised to 210℃, and the temperature was maintained at this temperature.
The reaction proceeded for 15 hours. Next, the resin concentration was adjusted to 30% by weight with cresol to obtain a varnish. The viscosity of this varnish is 250
There were poises, and the reduced specific viscosity of the resin measured in dimethylformamide was 0.23. The polyamide-imide resin varnish obtained as described above was applied and baked on a 1.0 mm diameter conductor to obtain an enameled wire. Comparative Example 3 5 weight parts each of PR-1501 (phenol formaldehyde resin manufactured by Hitachi Chemical Co., Ltd.) and Melan-20 (alkoxy-modified amino resin manufactured by Hitachi Chemical Co., Ltd.) were added to 100 parts by weight of the polyamide-imide resin in Comparative Example 2. Add parts at a time and adjust the resin concentration with cresol.
The polyamide-imide resin composition was adjusted to 30%, and this was coated and baked on a 1.0 mmφ conductor to obtain an enameled wire. Comparative Examples 4 and 5 and Examples 1 to 5 The polyamide-imide resin composition in Comparative Example 3 was used as an outer layer, and the polyimide resin in Comparative Example 1 was used as an inner layer, and the film thickness of the inner layer and outer layer was as shown in the table below. A double-coated enameled wire was obtained by coating and baking on a conductor. The characteristics of the various enamelled wires in the above comparative examples and examples are shown in the table below. The mechanical strength was evaluated using a reciprocating abrasion test in accordance with JIS-C3003, and the heat resistance was evaluated in accordance with the same standard by measuring the residual dielectric breakdown voltage after thermal deterioration of twisted pairs of samples at high temperatures.

【table】

[Table] As explained above, the present invention provides an insulated wire using a cresol solvent-soluble polyamide-imide resin as an outer layer and a polyimide resin as an inner layer.
An insulated wire with excellent mechanical strength and heat resistance and low cost can be obtained.

Claims (1)

[Claims] 1. Apply and bake a polyimide resin layer as an interpolation directly above the conductor, and on top of that, apply 1.00 equivalent of polycarboxylic acid containing an acid anhydride group and 0.01 to 0.30 equivalent of polyisocyanate containing isocyanurate ring as an outer layer.
Equivalent, the sum of the equivalents of aromatic diisocyanate and isocyanurate ring-containing polyisocyanate is 0.8~
A resin composition obtained by adding 0.10 to 15 parts by weight of an amino resin and a phenol resin to 100 parts by weight of a cresol-soluble polyamideimide resin obtained by reacting 1.50 equivalents and 0.30 to 0.90 equivalents of lactam in a cresol solvent. 0.5~20 of the inner layer
An insulated wire characterized by being coated and baked to double the thickness.