JPS6213767B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to an insulated wire that is highly compatible with varnish. Insulated wire coated with polyamide-imide resin has excellent heat resistance, refrigerant resistance, moisture resistance, and mechanical properties.
~ It is a heat-resistant enameled wire of the all-purpose H class, which is applied to various fields such as various H class equipment, coolers, air conditioners and other refrigerant-using equipment, and water-resistant motors, but its disadvantage is that it is expensive. ing. In recent years, in place of expensive polar solvent-soluble polyamide-imide resins, cresol-based solvent-soluble polyamide-imide resins as described below have been proposed.
However, when insulated wires coated with polyamide-imide resin that is soluble in cresol-based solvents are combined with epoxy-based varnish, the heat-resistant life of the insulated wires coated with conventional polyamide-imide resins that are soluble in polar solvents is reduced, and In some cases, it is barely class F. An object of the present invention is to provide an insulated wire coated with a cresol-based solvent-soluble polyamide-imide resin that has improved compatibility with epoxy-based treated varnish. The gist of the present invention is to use 1.00 equivalent of a polycarboxylic acid containing an acid anhydride group, 0.01 to 0.30 equivalent of an isocyanurate ring-containing polyisocyanate, and the sum of the equivalents of an aromatic diisocyanate and an isocyanurate ring-containing polyisocyanate. 0.80～
A resin composition and an inner layer obtained by adding 0.1 to 15 parts by weight of an amino resin and a phenolic resin to 100 parts by weight of a polyamideimide resin obtained by reacting 1.50 equivalents and 0.3 to 0.9 equivalents of lactam in a cresol solvent, and an inner layer. An insulated wire is characterized in that the outer layer is coated with polyimide resin on the circumference of the conductor and baked, and when the outer layer has a coating thickness of 1, the inner layer has a coating thickness of 0.5 to 20. . That is, the present invention solves the problem of decreased varnish resistance, decreased heat resistance, deterioration of appearance, etc. that occur when polyamide-imide resin is solubilized with cresol, by combining a specific polyamide-imide resin with a secondary additive resin, and by improving the composition of the polyimide layer. The overcoat significantly improves these drawbacks. 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, Pyre-ML varnish (manufactured by Du Pont, USA), Trenice #2000, #3000 (manufactured by Toray Industries, Inc.), and the like. In addition, in the present invention, when the outer layer film thickness is 1, when the inner layer film thickness is 0.5 or less, varnish resistance improves but the price increases, and when the inner layer film thickness is 20 or more, sufficient varnish resistance is obtained. is not obtained. In order to strike a balance between varnish resistance and price, it is preferable that when the outer layer has a thickness of 1, the inner layer has a thickness of 2 to 8. Hereinafter, specific examples of the present invention will be described while comparing them with comparative examples. For evaluation of varnish resistance, the insulated wires obtained in Comparative Examples 1 to 4 and Examples 1 to 4 were twisted in accordance with JIS.C3003 and treated with epoxy varnish.
The lifespan was evaluated by measuring the breakdown voltage at room temperature after thermal deterioration at high temperatures. Comparative example 1 Trenice #2000 (manufactured by Toray Industries, Inc.) varnish
An enamelled wire was obtained by coating and baking on a 1.0 mmφ conductor. Comparative Example 2 (1) Synthesis component equivalent of aromatic diisocyanate trimer 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. , heated 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 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 Example 4 and Examples 1 to 4 The polyamide-imide resin composition in Comparative Example 3 was used as an inner layer, the polyimide resin in Comparative Example 1 was used as an outer layer, and a conductor of 1.0 mmφ was made so that the film thickness of the inner layer and the outer layer were as shown in the table below. A double-coated enameled wire was obtained by coating and baking on top. The characteristics of the various enamelled wires in the above comparative examples and examples are shown in the table below.

[Table] As explained above, the present invention provides a double-coated insulated wire with an inner layer made of cresol-based solvent-soluble polyamide-imide resin and an outer layer made of polyimide resin, which has excellent compatibility with epoxy-based treated varnish, and It becomes possible to obtain inexpensive insulated wires.

Claims (1)

[Claims] 1 Polycarboxylic acid containing an acid anhydride group at 1.00
equivalent, the isocyanurate ring-containing polyisocyanate is 0.01 to 0.30 equivalent, the sum of the equivalents of the aromatic diisocyanate and the isocyanurate ring-containing polyisocyanate is 0.80 to 1.50 equivalent, and the lactam is 0.3 to 0.9 equivalent, and is obtained by reacting in a cresol solvent. The inner layer is a resin composition made by adding 0.1 to 15 parts by weight of an amino resin and a phenol resin to 100 parts by weight of a polyamide-imide resin, and the outer layer is made of a polyimide resin, which is coated on the circumference of the conductor and baked. An insulated wire characterized in that the inner layer has a coating thickness of 0.5 to 20 when the coating thickness of the inner layer is 1.