JPS6351324B2 - - 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 the coil surface and 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. Moreover, 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. The dried base material (A) is reacted with 1.2 to 10 equivalents of an epoxy resin per equivalent of the imide ring-containing dicarboxylic acid compound to obtain an imide-modified epoxy resin (B). After coating or impregnating the resin composition (D) obtained by reacting 0.1 to 0.8 equivalents of a saturated monobasic acid (C), the base material is B-staged by irradiation with light, which has excellent heat resistance. The inventors discovered that it is possible to obtain a prepreg with a similar shape, and 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 for the heat-resistant prepreg in the present invention is epoxy resin per equivalent of the imide ring-containing dicarboxylic acid compound.
1.2 to 10 equivalents were reacted to obtain imide-modified epoxy resin (B), and unsaturated monobasic acid (C) was added to 1 equivalent of (B).
It can be easily obtained by reacting 0.1 to 0.8 equivalents. If the amount of epoxy resin is less than 1.2 equivalents per equivalent of the imide ring-containing dicarboxylic acid compound, the molecular weight will become too large and the workability will decrease due to a decrease in solubility, and if it is more than 10 equivalents, sufficient heat resistance will not be obtained. Neither is preferable. In addition, if the amount of unsaturated monobasic acid (C) is less than 0.1 equivalent per equivalent of imide-modified epoxy resin (B), curing will not be sufficient during prepreg formation by light irradiation, and stickiness will remain; If there is too much, curing will progress too much during prepreg formation by light irradiation,
Both are unfavorable since the fusion properties are reduced. Imide ring-containing dicarboxylic acid compounds that can be used in the present invention include general formulas (), (),
()and(): (In the formula, R ¹ is an aliphatic or aromatic diamino residue having 1 to 24 carbon atoms, R ² is an aliphatic or aromatic aminocarboxylic acid residue having 1 to 20 carbon atoms, and R ³ is an aliphatic or aromatic aminocarboxylic acid residue having 1 to 24 carbon atoms. -10 aliphatic or aromatic tetracarboxylic acid residues, R ⁴ represents an aliphatic dicarboxylic acid residue). 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), Novolac type
Examples include DEN431, DEN438 (both manufactured by Dow Chemical Company), aliphatic type Chitsonox 221 and 289 (both manufactured by Chitso Corporation), 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 imide-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, thiosemicarbazide, 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 to 0.8 of an unsaturated monobasic acid is used per equivalent of imide-modified epoxy resin.
reacting equivalent amounts to form a partially photocurable composition;
Prepreg is created by light irradiation, then wound around a coil, etc., and then completely cured using a heating press, etc. There is no need for heating during prepreg production, and prepreg is produced by only short light irradiation, and the prepreg is cured. Furthermore, it has excellent heat resistance, especially electrical and mechanical properties in a high temperature range. 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 required. 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 a nonwoven fabric made by mixing 1 to 50% of polymeric fibrils with polyamide fiber as a base material and dispersing it in water. If the temperature is higher than 250°C, the rate of water evaporation is too fast, leading to non-uniformity in the texture of the nonwoven fabric, both of which are unfavorable. 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 imide ring-containing dicarboxylic acid compounds represented by the general formulas () to () above, the abbreviations and structural formulas of specific compounds of the general formulas () and () 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 polymeric fibrils consisting of m-phenylenediamine and isophthalic acid and dispersing it in water was heated at 180°C.
A base material was obtained by heating and drying for a period of time. 27.3 of imide ring-containing dicarboxylic acid compound IC-1
g (0.1 equivalent) and 95 g (0.5
0.01 g of benzyltriethylammonium chloride as a catalyst and reacted at 150° C. for 1 hour to obtain an imide-modified epoxy resin with an epoxy equivalent of 300. 600g (2.0 equivalent) of this imide-modified epoxy resin
Add 86g (1.0 equivalent) of methacrylic acid to 120
The reaction was carried out at ℃ for 2 hours. 0.8 g of benzoin ethyl ether as a photosensitizer to 100 g of the resin produced
Then, 2.0 g of boron trifluoride monoethylamine complex as a curing agent for epoxy resin was added to prepare a heat-resistant resin composition. 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 wrap around a coil conductor, and then cured at 110℃ for 3 hours and 180℃ for 10 hours to obtain an insulated coil.
Its electrical characteristics (dielectric loss tangent (tan δ) temperature characteristics, 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. Next, a prepreg was produced in the same manner as in Example 1 except that the base material was used. Table 1 shows the properties of the obtained prepreg. Example 3 21.9 of imide ring-containing dicarboxylic acid compound IC-2
g (0.1 equivalent) and 57.0 g of bisphenol A type epoxy resin Epicote 828 (manufactured by Ciel Chemical Co., Ltd.)
(0.3 equivalent) and reacted at 150° C. for 1 hour using 0.02 g of benzyltriethylammonium bromide as a catalyst to obtain an imide-modified epoxy resin with an epoxy equivalent of 400. 800g (2.0 equivalent) of this imide-modified epoxy resin
To this, add 43g (0.5 equivalent) of methacrylic acid,
The reaction was carried out at 120°C for 2 hours. 0.5 benzoin ethyl ether as a photosensitizer to 100g of the resin produced
g, 3.0 g of tricresyl borate and 3.0 g of triethanolamine titanate were added as curing agents for the epoxy resin 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] Comparative example 1 Epicote 1001 (manufactured by Ciel Chemical Co., Ltd.) 800g,
A mixture of 100 g of ECN1273 (manufactured by Ciba Geigy), 30 g of dicyandiamide, and 2.0 g of 2-ethyl-4-methylimidazole, and 400 g of methyl cellosolve as a solvent was impregnated into Tetron cloth as a base material at room temperature. at 120℃
A prepreg sheet was obtained by drying for 10 minutes. The same test as in Example 1 was conducted using the obtained prepreg sheet. The results are shown in Table 2. Comparative Example 2 A prepreg sheet was obtained using the same resin composition as that used in Comparative Example 1, using a glass tape as a base material. The same test as in Example 1 was conducted using the obtained prepreg sheet. The results are shown in Table 2. Comparative Example 3 The same procedure as in Example 1 was used except that a nonwoven fabric obtained by using the same polymeric fibrils used in Example 1 at 150 parts (60% by weight) per 100 parts of aromatic polyamide polymer fibers was used. A prepreg was produced. The same test as in Example 1 was conducted using the obtained prepreg sheet. The results are shown in Table 2. Comparative Example 4 Same as Example 1 except that a nonwoven fabric obtained by using the same polymeric fibrils used in Example 1 at 0.5 parts (approximately 0.5% by weight) per 100 parts of aromatic polyamide polymer fibers was used. However, due to the low strength of the nonwoven fabric, it was not possible to obtain a sheet with sufficient performance. Comparative Example 5 27.3 of imide ring-containing dicarboxylic acid compound IC-1
(0.1 equivalent) and 228 g (1.2 equivalent) of Epicote 828 were mixed and reacted at 150° C. for 1 hour using 0.02 g of benzyltriethylammonium chloride as a catalyst to obtain an imide-modified epoxy resin with an epoxy equivalent of 240. 480g (2.0 equivalent) of this imide-modified epoxy resin
To this, add 86 g (1.0 equivalent) of methacrylic acid,
The reaction was carried out at 120°C for 2 hours. Add 0.8g of benzoin ethyl ether as a photosensitizer to 100g of the resin produced.
Then, 2.0 g of boron trifluoride monoethylamine complex was added as a curing agent for the epoxy resin to obtain a heat-resistant resin composition. The heat-resistant resin composition was applied to the same nonwoven fabric as used in Example 1, and a prepreg sheet was manufactured under the same conditions as in Example 1. The same test as in Example 1 was conducted using the obtained prepreg sheet. The results are shown in Table 2. Comparative Example 6 273 of imide ring-containing dicarboxylic acid compound IC-1
g (1 equivalent) and 209 g (1.1 equivalent) of Epicote 828
Using 0.02 g of benzyltriethylammonium chloride as a catalyst, the mixture was reacted at 150°C for 1 hour to obtain an imide-modified epoxy resin with an epoxy equivalent of 4500. The obtained imide-modified epoxy resin had a high viscosity due to its large molecular weight, and even when reacted with methacrylic acid, the viscosity did not become sufficient to impregnate the base material. Comparative Example 7 Imide-modified epoxy resin obtained in Example 1
8.6g methacrylic acid per 600g (2.0 equivalents)
(0.1 equivalent) was added and reacted at 120°C for 1 hour.
0.8 g of benzoin ethyl ether as a photosensitizer and boron trifluoride monoethylamine complex as a curing agent for epoxy resin to 100 g of the resin produced.
2.0g was added to obtain a heat-resistant resin composition. The obtained heat-resistant resin composition was applied to the same nonwoven fabric as used in Example 1 and exposed to a 2.5KW mercury lamp for about 5 minutes, but the resin remained sticky and had poor workability as a prepreg. I couldn't go back. Comparative Example 8 Imide-modified epoxy resin obtained in Example 1
154.8g of methacrylic acid per 600g (2.0 equivalent)
(1.8 equivalents) was added and reacted at 120°C for 1 hour.
0.8 g of benzoin ethyl ether as a photosensitizer and boron trifluoride monoethylamine complex as a curing agent for epoxy resin to 100 g of the resin produced.
2.0g was added to obtain a heat-resistant resin composition. The obtained heat-resistant resin composition was applied to the same nonwoven fabric as used in Example 1, and four sheets of prepreg produced by exposing it to a 2.5 KW mercury lamp for about 5 minutes were stacked and cured at 150 ° C. for 15 hours. However, it did not fuse sufficiently,
Peeling occurred between the layers. Although the exposure time to the mercury lamp was shortened, it was difficult to control the reaction, and only prepregs with poor workability could be obtained.

[Table] From the results in Table 2, in the case of Comparative Example 3, a decrease in properties was observed, which is believed to be due to a decrease in the impregnation of the resin into the base material. Furthermore, it can be seen that Comparative Example 5 has poor heat resistance.

Claims (1)

[Claims] 1 Polymer fibrid to polyamide fiber 1~
1.2 to 10% of epoxy resin per equivalent of imide ring-containing dicarboxylic acid compound is added to the base material (A), which is made by heating and drying a nonwoven fabric made by mixing 50% by weight and sprinkling it in water to make paper.
React equivalent amounts to obtain imide-modified epoxy resin (B), and add 0.1 unsaturated monobasic acid (C) to 1 equivalent of (B).
A method for producing a heat-resistant prepreg, which comprises applying or impregnating a resin composition (D) obtained by reacting an amount of ~0.8 equivalent, and then B-staged by irradiating the base material with light.