JPS625450B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a novel method for producing heat-resistant prepreg. More specifically, the present invention relates to a method for producing a prepreg that is semi-hardened, flexible, and has excellent heat resistance for interlayer insulation of coils for electrical equipment or insulation of slots, leads, etc. The conventional method of insulating coils for electrical equipment using semi-cured prepreg insulation sheets or prepreg insulation tapes does not require operations such as brushing or impregnating with insulation varnish, so it is cost-effective. This is an extremely advantageous method in terms of production time, and for producing these prepregs, a latent curing agent such as boron trifluoride amine complex salt or dicyandiamide is blended with an epoxy resin that has excellent properties for the cured product as a prepreg resin. Epoxy resin compositions are widely used. In addition, as base materials for prepreg, inorganic fiber base materials such as glass cloth, organic fiber base materials such as Tetron cloth, heat-shrinkable films, paper, mica sheets, etc. are used. However, prepregs obtained using conventional epoxy resin compositions are not fully satisfactory in terms of heat resistance, water resistance, etc., and have the disadvantage of poor electrical and mechanical properties, especially in high temperature ranges. In addition, heating is required during prepreg production, making the production process extremely complicated. As a result of intensive research to overcome the above-mentioned drawbacks, the inventors of the present invention have found that a nonwoven fabric made by mixing 1 to 50% (by weight) of polymeric fibrils with polyamide fibers and dispersing it in water to make paper is heated. Quinazolone ring-containing dicarboxylic acid compound 1 is added to the dried base material (A).
A quinazolone-modified epoxy resin (B) is obtained by reacting 1.2 to 10 equivalents of epoxy resin with respect to the equivalent amount, and 1 of (B) is obtained.
When applying or impregnating a resin composition (D) obtained by reacting 0.1 to 0.8 equivalents of unsaturated monobasic acid (C) with respect to the equivalent amount, the base material is B-staged by irradiation with light. We have discovered that a prepreg with excellent heat resistance can be obtained, and have completed the present invention. In other words, according to the present invention, prepregs can be easily produced by simply irradiating light for a short time without going through a complicated heat treatment process, and the properties after molding are excellent in heat resistance, especially in the high temperature range. A very remarkable effect is achieved in that a molded product with excellent electrical and mechanical properties can be obtained. Furthermore, the heat-resistant prepreg according to the present invention has a long shelf life and can sufficiently possess the properties of a prepreg. The heat-resistant resin (i.e., prepreg resin) used in the heat-resistant prepreg in the present invention is prepared by reacting 1.2 to 10 equivalents of an epoxy resin with 1 equivalent of a quinazolone ring-containing dicarboxylic acid compound to obtain a quinazolone-modified epoxy resin (B). It can be easily obtained by reacting 1 equivalent of unsaturated monobasic acid (C) with 0.1 to 0.8 equivalents of unsaturated monobasic acid (C). If the amount of epoxy resin per equivalent of the quinazolone ring-containing dicarboxylic acid compound is less than 1.2 equivalents, the molecular weight of the resin produced will increase, the softening temperature will rise, and the solubility will decrease, resulting in decreased workability. If the amount is too large, the heat resistance will be insufficient, which is not preferable. Furthermore, if the amount of unsaturated monobasic acid (C) is less than 0.1 equivalent per equivalent of quinazolone-modified epoxy resin (B), the adhesiveness of the produced prepreg will increase and workability will decrease; Curing progresses too much in the prepreg stage and the fusion properties of the prepreg material decrease, both of which are undesirable. The quinazolone ring-containing dicarboxylic acid compound used in the present invention has the general formula (): (In the formula, R ¹ represents an aliphatic or aromatic divalent group having 1 to 20 carbon atoms, and R ² represents an aliphatic or aromatic monovalent group having 1 to 20 carbon atoms.) Examples include compounds that The epoxy resin used in the present invention includes:
For example, bisphenol A diglycidyl ether type Epicote 828, Epicote 834 (all manufactured by Schiel Chemical Co., Ltd.), DER331, DER332 (all manufactured by Dow Chemical Company), and Novolac type.
DEN431, DEN438 (both manufactured by Dow Chemical Company), aliphatic type Chitsonox 221, 289
(all manufactured by Chitsuso Co., Ltd.), but are not limited to these. Examples of the unsaturated monobasic acids used in the present invention include acrylic acid, methacrylic acid, sorbic acid, and cinnamic acid. Furthermore, by using a catalyst such as a quaternary ammonium salt or a tertiary amine in the reaction between the quinazolone-modified resin and the unsaturated monobasic acid, the reaction can be carried out more smoothly. In addition, for the purpose of preventing gelation during the synthesis reaction of heat-resistant resin compositions and improving the storage stability after synthesis, hydroquinone, parabenzoquinone, hydroquinone monomethyl ether, phenothiazine, thiosemicarbazate, acetone thiocarbazone copper Salt or the like may be added, usually in a range of 0.001 to 1.0%. Furthermore, a photosensitizer is added to the heat-resistant resin composition at a rate of 0.5 parts (parts by weight, the same applies hereinafter) per 100 parts (parts by weight, the same applies hereinafter) of the heat-resistant resin composition.
By adding ~5 parts, curing can be further facilitated. If the amount of photosensitizer added is outside the above range, an appropriate effect of accelerating curing cannot be obtained, which is not preferable. Examples of such photosensitizers include carbonyl compounds such as benzoin and benzoin derivatives such as benzoin methyl ether, benzoin ethyl ether, and benzoin isopropyl ether, quinone compounds such as anthraquinone and naphthoquinone, and diphenyl sulfide. Examples include organic sulfur compounds such as, peroxides such as benzoin peroxide, nitrogen compounds such as azobisisobutyronitrile, and photoreducible dyes such as methylene blue and p-toluenesulfonate ion. In addition, in the production method of the present invention, 0.1 unsaturated monobasic acid is used per equivalent of quinazolone-modified epoxy resin.
~0.8 equivalents are reacted to form a partially photocurable composition, which is then irradiated with light to create a prepreg, which is then wound into a coil or the like and then completely cured using a heated press, etc., which eliminates the need for heating during prepreg production. After curing, the prepreg has excellent heat resistance, especially electrical properties and mechanical properties at high temperatures. At that time, if necessary, a vinyl monomer may be added to the heat-resistant composition without reducing its effect, but the amount thereof is preferably 20% or less. If the blending amount of the vinyl monomer exceeds 20%, the heat resistance of the prepreg will decrease, which is not preferable. Furthermore, in the present invention, as an epoxy curing catalyst, for example, metal salts such as tricresyl borate, cobalt acetylacetonate, zinc octinate, stannic octinate, triethanolamine titanate, metal chelate compounds,
Complexes of Lewis acids and amines such as BF ₃ , BCl ₃ , PF ₅ , AsF ₅ , metal olefin compounds such as ferrocene, etc. may be mixed and used as necessary. The heat-resistant resin composition (D) prepared as described above may be mixed with dioxane, methyl ethyl ketone,
It is dissolved in an organic solvent such as N,N-dimethylacetamide, N,N-dimethylformamide, or N-methylpyrrolidone, and applied or impregnated onto the substrate (A). As a base material for the heat-resistant prepreg of the present invention, the prepreg has high mechanical strength, good compatibility with the prepreg resin, and excellent properties such as thermal properties, electrical properties, and mechanical properties after curing. It satisfies all of the above requirements, and uses a nonwoven fabric that is mainly made of polyamide fibers, mixed with 1 to 50% of polymer fibrils, dispersed in water, made into paper, heated and dried. As a polymer fibrid as a fusion agent,
Examples include short fibers such as aromatic polyamide and polyacrylonitrile. If the content of polymer fibrils is less than 1%, it will lack mechanical strength as a base material, and if it is more than 50%, the impregnating properties of the heat-resistant resin composition will deteriorate, resulting in a cured product. electrical characteristics,
Mechanical properties deteriorate, both of which are unfavorable. Examples of the polyamide fibers used in the present invention include isophthalic acid-m-phenylenediamine copolymer and terephthalic acid-p-phenylenediamine copolymer. A temperature range of 50 to 250°C is suitable for heating and drying the nonwoven fabric, which is made by mixing 1 to 50% of polymeric fibrils with polyamide fiber as a base material and dispersing it in water to make paper. If the drying temperature is insufficient, there will be a large amount of undried residue, and if the temperature is higher than 250°C, water evaporation will be too rapid and the structure of the nonwoven fabric will not be uniform, both of which are undesirable. Furthermore, the conditions for optical prepreg formation of the base material coated or impregnated with the heat-resistant resin composition include room temperature.
Light irradiation times of 0.1 to 60 minutes are employed. As a result, a heat-resistant prepreg with excellent electrical properties, mechanical properties, and heat resistance can be obtained. The heat-resistant prepreg is wound around a conductor such as a coil and then heated and pressurized to form a cured product. Furthermore, the obtained cured product has excellent heat resistance, particularly excellent electrical and mechanical properties in a high temperature range, and can withstand long-term use at high temperatures. Next, the method for producing the heat-resistant prepreg of the present invention will be explained with reference to Examples. Here, among the quinazolone ring-containing dicarboxylic acid compounds represented by the general formula (), the abbreviations and structural formulas of the compounds used in the examples are shown below. Example 1 For 100 parts of aromatic polyamide polymer fiber consisting of m-phenylenediamine and terephthalic acid,
A nonwoven fabric made by mixing 50 parts (approximately 33% by weight) of a polymeric fibril consisting of m-phenylenediamine and isophthalic acid and dispersing it in water was heated to 180°C.
A base material was obtained by heating and drying for a period of time. Quinazolone ring-containing dicarboxylic acid compound QC-1
28.6g (0.1 equivalent) of epoxy resin Epicoat
828 (manufactured by Ciel Chemical Co., Ltd.) and reacted with 0.02 g of benzyltriethylammonium chloride as a catalyst at 150° C. for 1 hour to obtain a quinazolone-modified epoxy resin with an epoxy equivalent of 310. 86 g (1.0 equivalent) of methacrylic acid was added to 620 g (0.2 equivalent) of this quinazolone-modified epoxy resin, and the mixture was reacted at 120° C. for 2 hours. Resin produced
Add 0.8 g of benzoin ethyl ether as a photosensitizer and 2.0 g of boron trifluoride monoethylamine complex as a curing agent for epoxy resin to 100 g,
A heat-resistant resin composition was prepared. The obtained heat-resistant resin composition was applied to the base material and exposed to a 2.5 KW mercury lamp for about 5 minutes to obtain a prepreg. In order to understand the mechanical properties of the obtained prepreg, Table 1 shows the properties of four prepreg sheets cut out to 25 mm x 25 mm and cured at 150°C for 15 hours. The adhesive strength was measured using an Instron tensile tester at a temperature of 20°C, using an initial value and a value after deterioration after heat treatment at 220°C for 20 days. Furthermore, prepare a prepreg sheet of 2mm x 5mm x 500mm.
A bundle of 10 formal rectangular copper wires was wrapped four times in a wrapper around a coil conductor, and then cured at 110℃ for 3 hours and 180℃ for 10 hours to obtain an insulated coil. The temperature characteristics (tanδ) and dielectric breakdown voltage) were measured. The dielectric loss tangent temperature characteristics are measured at a voltage of 0.5KV at temperatures of 20℃ and 200℃ for the obtained insulated coil.
It was measured by the high-pressure Schering bridge method (using a Schering bridge manufactured by Yokogawa Electric Corporation). The breakdown voltage of the insulated coil is 220℃.
An insulated coil (after deterioration) that has been heat treated for 20 days is heated to a temperature of 25
It was measured in oil at a constant pressure increase rate of 1 KV/sec at ℃ using a withstand voltage tester (manufactured by Aikoku Denki Co., Ltd.). Example 2 For 100 parts of aromatic polyamide polymer fiber consisting of m-phenylenediamine and terephthalic acid,
A nonwoven fabric made by mixing 10 parts (approximately 9% by weight) of a polymeric fibril consisting of m-phenylenediamine and isophthalic acid and dispersing it in water was heated at 150℃ for 30 minutes.
The substrate was dried by heating for a minute. A heat-resistant resin composition obtained in the same manner as in Example 1 was applied to the base material and exposed to sunlight for 20 minutes to produce a prepreg. Table 1 shows the properties of the obtained prepreg. Example 3 Quinazolone ring-containing dicarboxylic acid compound QC-2
28.6g (0.1 equivalent) of epoxy resin Epicoat
828 (manufactured by Ciel Chemical Co., Ltd.) and 57.0 g (0.3 equivalents) of the mixture were mixed, and reacted at 150°C for 1 hour using 0.05 g of benzyltriethylammonium bromide as a catalyst.
A quinazolone-modified epoxy resin with an epoxy equivalent of 430 was obtained. 43 g (0.5 equivalent) of methacrylic acid was added to 860 g (2.0 equivalent) of this quinazolone-modified epoxy resin, and the mixture was reacted at 120° C. for 2 hours. Resin produced
0.5 g of benzoin ethyl ether as a photosensitizer, 3.0 g of tricresyl borate and 3.0 g of triethanolamine titanate as curing agents for epoxy resin were added to 100 g to prepare a heat-resistant resin composition.
The heat-resistant resin composition was applied to a base material obtained in the same manner as in Example 2, and exposed to a 2.5 KW mercury lamp for 10 minutes to obtain a prepreg. Table 1 shows the properties of the obtained prepreg.

【table】

【table】

Claims (1)

[Claims] 1 Polymer fibrid to polyamide fiber 1~
The base material (A) is made by heating and drying a nonwoven fabric made by mixing 50% by weight of the mixture and dispersing it in water, and then adding 1.2% of the epoxy resin to 1 equivalent of the quinazolone ring-containing dicarboxylic acid compound.
~10 equivalents were reacted to obtain quinazolone-modified epoxy resin (B), and unsaturated monobasic acid (C) was added to 1 equivalent of (B).
A method for producing a heat-resistant prepreg, which comprises coating or impregnating a resin composition (D) obtained by reacting 0.1 to 0.8 equivalents, and then B-staged by irradiating the base material with light.