JPS6139689B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Field of Application] The present invention relates to an insulated wire formed by coating and baking a main coating of cresol-based solvent-soluble polyamide-imide paint which has excellent resistance to applied moisture. [Conventional technology] As electrical equipment becomes smaller and lighter, heat-resistant insulated wires are being used more frequently, and insulated wires made of polyamide-imide resin are attracting attention as they have a variety of properties. has been done. However, since conventional polyamide-imide resins are only soluble in expensive polar solvents, various studies have been made on polyamide-imide resins that are soluble in inexpensive cresol solvents. Among these, isocyanurate ring-containing polyisocyanates, aromatic diisocyanates, lactams,
An insulated wire using a cresol solvent-compatible polyamideimide resin obtained by reacting a polycarboxylic acid containing an acid anhydride group in a cresol solvent has been proposed. Although this insulated wire has characteristics equivalent to or better than conventional insulated wire using polar solvent-soluble polyamide-imide resin in various aspects, the inventors have found that it is slightly inferior in moisture resistance under electric charge. We found this out through experiments. [Problems to be Solved by the Invention] The present invention has been made based on the above points, and its purpose is to solve the above-mentioned drawbacks of the prior art and to provide a cresol with excellent resistance to static electricity and moisture. An object of the present invention is to provide a solvent-soluble polyamide-imide insulated wire. [Means for Solving the Problems] The gist of the present invention is to provide an undercoat polyamideimide layer formed by coating and baking a polar solvent-soluble polyamideimide paint directly on a conductor, and an upper layer of the undercoat polyamideimide layer. In an insulated wire comprising a top-coat polyamide-imide layer formed by coating and baking a cresol-based solvent-soluble polyamide-imide paint, the top-coat polyamide-imide layer contains 1.00% polycarboxylic acid containing an acid anhydride group in a cresol solvent. equivalent, 0.01 to 0.30 equivalent of isocyanurate ring-containing polyisocyanate, 0.80 to 1.50 equivalent of the sum of equivalents of aromatic diisocyanate and isocyanurate ring-containing polyisocyanate, and 0.3 equivalent of lactam.
For 100 parts by weight of cresol-based solvent-soluble polyamide-imide resin reacted at a ratio of ~0.9 equivalents,
amino gun resin and phenolic resin respectively
The insulated wire is made of a polyamide resin composition containing 0.1 to 15 parts by weight, and the undercoat polyamide-imide layer has a thickness of 1 μm or more. The isocyanurate ring-containing polyisocyanate, which is the raw material for the cresol solvent-soluble polyamideimide resin used in the present invention, is obtained by trimerizing a polyisocyanate compound, and this reaction is carried out in the presence of a solvent that does not react with isocyanate groups. In order to carry out the reaction without adding components that react with isocyanate groups such as phenols, lactams, etc., and to proceed with the reaction efficiently, it is desirable to use a trimerization catalyst of polyisocyanate compounds. 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, and the like. Trimerization catalysts for polyisocyanate compounds include alkali metal acetates, metal salts such as iron, magnesium, nickel, zinc, tin, lead, vanadium, titanium, etc., and organic compounds, N-methylmorpholine, 1,8-diazabinchro( 5,4,0)
Undecane-7,2-(dimethylaminomethyl)
Mannitz bases of phenols such as -4,6-dimethylphenol and tertiary amines such as 2-dimethylaminoethanol can be used. 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, are preferred. , 4,4'-diphenyl ether diisocyanate and the like are preferred. Polyisocyanate containing isocyanate rings has a residual isocyanate group content of 10% from the viewpoint of heat resistance and flexibility.
The range is preferably 70% (assuming the amount of isocyanate groups combined in the raw material isocyanate is 100). Also,
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. Lactams, which are important raw materials 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 (considering ε-caprolactam to be difunctional) based on the total isocyanate equivalents in terms of heat resistance, flexibility and solubility. Preferred aromatic diisocyanates include 4,4'-diphenylmethane diisocyanate, 4,4'-diphenyl ether disocyanate, tolylene diisocyanate, and xylylene diisocyanate. As the polycarbonic acid containing an acid anhydride group, trimethic anhydride is preferable 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 oxidized 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-containing polycarboxylic acid is added, and the reaction is further continued at 200-220°C for 10-20 hours. The polyamide cymide resin thus obtained has particularly good properties as an insulated wire if it has a ring specific viscosity of 0.15 or more when measured in dimethylformamide. The 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 amount is exceeded, the flexibility of the enameled wire decreases. 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. The polar solvent-soluble polyamide-imide resin used in the present invention is prepared by reacting tribasic acid anhydride halide and aromatic diamine in a polar solvent such as dimethylacetamide, or aromatic diisocyanate and trimellitic anhydride. There are also those made by reacting in a polar solvent. The coating layer made of a polar solvent-soluble polyamide imide resin is the upper layer, and the polar solvent coating layer must have a thickness of 1 μm or more in order to obtain sufficient electrical resistance to moisture. [Function] The insulated wire of the present invention maintains the cresol solubility, which is a characteristic of cresol-based solvent-soluble polyamideimide, while effectively improving its shortcomings in resistance to electricity and moisture. That is, by blending 0.01 to 0.30 equivalent % of isocyanurate ring-containing polyisocyanate and 0.3 to 0.9 equivalent % of lactam, cresol solubility and resistance to electric charge and humidity are maintained, and furthermore, 0.1 to 15% by weight of amino resin and phenol resin are blended. By adding 100% of the polyamide-imide layer, the thermosetting reaction of the coating film is promoted to prevent water intrusion and moisture permeation under high humidity conditions.Furthermore, by providing a polar solvent-soluble polyamide-imide layer as the lower layer, moisture permeation and intrusion are prevented directly above the conductor. This prevents the generation of metal ions, and these act synergistically to exhibit excellent resistance to electrical charges and moisture. [Examples] Specific examples of the present invention will be described below in comparison with comparative examples. Comparative Example 1 (1) Components for synthesis of aromatic diisocyanate trimer Gram 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°C in a nitrogen stream, and the reaction was allowed to proceed at the same temperature until the content of isocyanate groups (initial concentration: 48% by weight) reached 25% by weight. (2) Synthesis of cresol solvent-soluble polyamideimide resin

[Table] Place the above ingredients except trimellitic anhydride into four flasks equipped with a thermometer, a stirrer, and a fractionating tube, raise the temperature to 180°C in a nitrogen stream, and react for 90 minutes. Next, trimellitic anhydride was added, the temperature was raised to 210°C, and the reaction was continued at this temperature for 15 hours. Next, the resin concentration was adjusted to 30% by weight with cresol to obtain a wa varnish. The viscosity of this varnish was 250 boads, 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 2 PR-1501 for 100 parts by weight of the cresol solvent-soluble polyamide-imide resin in Comparative Example 1
(phenol formaldehyde resin manufactured by Hitachi Chemical Co., Ltd.) and Melan-20 (alkoxy-modified amino resin manufactured by Hitachi Chemical Co., Ltd.) were added in an amount of 5 parts by weight each, and the resin concentration was adjusted to 30% with cresol to form a polyamide-imide resin. A composition was prepared, and this was coated and baked on a 1.0 mmφ conductor to obtain an enameled wire. Comparative Example 3 Synthetic components of polar solvent-soluble polyamide resin Gram trimellitic anhydride 192 (1 mol) 4,4'-diisocyanate 250 (1 mol) Diphenylmethane dimethylacetamide 400 The above components were mixed in a four-necked flask at 120 ml. The reaction was allowed to proceed at ~150°C, and the reaction was stopped when the reduced specific viscosity of the resin in dimethylacetamide reached 0.4.Then, the resin concentration was adjusted to 30% with dimethylacetamide to obtain a varnish. This varnish was used as an outer layer, and the cresol-based solvent-soluble polyamide-imide resin varnish in Comparative Example 1 was used as an inner layer, and the film was coated and baked on a 1.0 mmφ conductor so that the film thicknesses of the outer layer and inner layer were as shown in the attached table. I got it. Comparative Example 4 The polar solvent-soluble polyamideimide resin varnish in Comparative Example 3 and Example 1 was used as the outer layer, Comparative Example 2
A double-coated enameled wire was obtained by applying and baking the cresol-based solvent-soluble polyamide-imide resin composition varnish as an inner layer onto a 1.0 mmφ conductor so that the film thicknesses of the outer layer and inner layer were as shown in the attached table. Comparative Example 5 The polar solvent-soluble polyamide-imide resin varnish of Comparative Example 3 was used as the inner layer, and the cresol-based solvent-soluble polyamide-imide resin composition varnish of Comparative Example 2 was used as the outer layer, so that the film thicknesses of the inner and outer layers were as shown in the attached table. A double-coated enamelled wire was obtained by coating and baking on a 1.0 mmφ conductor. Example 1 The polar solvent-soluble polyamide-imide resin varnish in Comparative Example 3 was used as the inner layer, and the cresol-based solvent-soluble polyamide-imide resin composition varnish in Comparative Example 2 was used as the outer layer, so that the film thicknesses of the inner layer and the outer layer were as shown in the attached table. A double-coated enamel wire was obtained by coating and baking it on a 1.0 mmφ conductor. Example 2 Similarly, the polar solvent-soluble polyamide-imide resin varnish in Comparative Example 3 was used as the inner layer, and the cresol-based solvent-soluble polyamide-imide resin composition varnish in Comparative Example 2 was used as the outer layer, and the film thicknesses of the inner and outer layers were as shown in the attached table. A double-coated enamel wire was obtained by coating and baking on a 1.0 mmφ conductor. Example 3 Similarly, the polar solvent-soluble polyamide-imide resin varnish in Comparative Example 3 was used as the inner layer, and the cresol-based solvent-soluble polyamide-imide resin composition varnish in Comparative Example 2 was used as the outer layer, and the film thicknesses of the inner and outer layers were as shown in the attached table. A double-coated enamel wire was obtained by coating and baking on a 1.0 mmφ conductor. The characteristics of the enamelled wires thus obtained in the comparative examples and examples are shown in Table 1.

〔Effect of the invention〕

Although the insulated wire of the present invention is coated with a polyamide-imide paint soluble in a cresol solvent as the main coating and baked, it has excellent resistance to electricity and moisture, and can be used in high humidity environments or It is useful as a magnet wire for motors used underwater.

Claims (1)

[Claims] 1 An undercoat polyamide-imide layer formed by applying a polar solvent-soluble polyamide-imide paint directly on the conductor and baking it, and an overcoat polyamide layer formed by applying a cresol-based solvent-soluble polyamide-imide paint on the upper layer of the undercoat polyamide-imide layer and baking it. In the insulated wire comprising an imide layer, the top coated polyamide-imide layer contains 1.00 equivalents of a polycarboxylic acid containing an acid anhydride group, 0.01 to 0.30 equivalents of an isocyanurate ring-containing polyisocyanate, and an aromatic diisocyanate and an isocyanate in a cresol solvent. The sum of equivalent weights of nurate ring-containing polyisocyanate is 0.80~
A polyamide-imide resin composition in which 0.1 to 15 parts by weight of an amino resin and a phenolic resin are added to 100 parts by weight of a cresol-based solvent-soluble polyamide-imide resin obtained by reacting 1.50 equivalents and a lactam in a ratio of 0.3 to 0.9 equivalents. 1. An insulated wire, characterized in that the undercoat polyamide-imide layer has a thickness of 1μ or more.