JPS6366011B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a novel method for manufacturing heat resistant prepreg insulation. More specifically, it is used for interlayer insulation of coils for electrical equipment or insulation of slots, leads, etc. It is flexible in a semi-cured state, exhibits self-bonding properties when heated, and has excellent heat resistance, especially in high temperature ranges. This invention relates to a method for producing a heat-resistant prepreg insulator that provides a cured product with excellent electrical and mechanical properties. The method of insulating coils for electrical equipment using semi-cured prepreg insulating sheets or prepreg insulating tapes does not require operations such as brushing or impregnating with insulating varnish, so it is effective in terms of cost and manufacturing time. This is an extremely advantageous method,
In the production of these prepreg insulators, epoxy resin compositions are widely used as prepreg resins, which are made by blending latent curing agents such as boron trifluoride amine complex salts and dicyandiamide with epoxy resins that have excellent properties when cured. ing. In addition, as base materials for prepreg insulators, inorganic fiber base materials such as glass cloth, organic fiber base materials such as Tetron cloth, heat shrink films, paper, mica sheets, etc. are used. However, the prepreg insulator obtained using the conventional epoxy resin composition described above has a shelf life of about 3 to 4 months at room temperature at most, and does not have sufficient performance as a prepreg insulator. It's hard to say that there are. Moreover, the resulting cured product is not fully satisfactory in terms of heat resistance, water resistance, etc., and has the drawback of poor electrical and mechanical properties, particularly in a high temperature range. The present inventors have developed a heat-resistant prepreg insulator that eliminates the above-mentioned drawbacks and provides a cured product that has good storage stability, excellent heat resistance, and particularly excellent electrical and mechanical properties at high temperatures. As a result of extensive research in order to provide a manufacturing method, we have completed the present invention. That is, the present invention uses as a base material a two-layer structure made by thermally fusing laminated mica paper and aromatic polyamide paper containing 1 to 5% (by weight, the same applies hereinafter) of polymeric fibrils as a fusing agent, and A method for producing a heat-resistant prepreg insulator, which is coated or impregnated with a heat-resistant resin composition comprising an imide-modified epoxy resin, a diamino compound, and a polyfunctional bismaleimide compound, and then heat-dried to a semi-cured state, Heat-resistant prepreg insulation, which is flexible in a semi-cured state and exhibits self-bonding properties when heated, by the production method of the present invention using the above-mentioned specific base material and heat-resistant resin composition when insulating coils for electrical equipment, etc. Due to the use of prepreg insulation, the cured product produced by conventional manufacturing methods lacks thermal stability, has poor electrical and mechanical properties in high temperature ranges, and can be used at high temperatures for long periods of time. It has the extremely remarkable effect of completely eliminating the disadvantages mentioned above, such as not being able to withstand use, and producing a cured product with excellent heat resistance and particularly excellent electrical and mechanical properties in a high temperature range. be done. Furthermore, the heat-resistant prepreg insulator produced by the manufacturing method of the present invention has a long shelf life and can sufficiently exhibit the performance of a prepreg insulator. The heat-resistant resin composition (i.e., prepreg resin) used in the production method of the present invention is composed of an imide-modified epoxy resin, a diamino compound, and a polyfunctional bismaleimide compound, and is composed of an imide-modified epoxy resin, a diamino compound, and a polyfunctional bismaleimide compound. A functional epoxy compound is reacted at a ratio of 1.6 to 50 equivalents of epoxy groups to obtain an epoxy resin containing an imide ring (i.e., an imide-modified epoxy resin), and diamino 5 to 100 parts of the compound and 5 to 500 parts of the polyfunctional bismaleimide compound are blended. In this heat-resistant resin composition, the epoxy resin containing a highly heat-resistant imide ring and the maleimide group of the polyfunctional bismaleimide compound are cross-linked with the diamino compound to form a highly heat-resistant cross-linked structure. Provides a cured product with excellent heat resistance, electrical properties, and mechanical properties. If the reaction ratio of the polyfunctional epoxy compound is less than 1.6 equivalents of epoxy to 1 equivalent of the carboxyl group of the dicarboxylic acid compound containing an imide ring, the molecular weight of the imide-modified epoxy resin produced will increase too much, resulting in poor solubility in the solvent. The epoxy equivalent becomes 50.
If the amount is larger than the equivalent, the resulting cured product will have insufficient heat resistance, which is not preferable. When the blending ratio of the polyfunctional bismaleimide compound is less than 5 parts per 100 parts of the imide-modified epoxy resin, there is no blending effect of the polyfunctional bismaleimide compound, and
When the amount is more than 500 parts, the heat resistance of the resulting cured product improves, but the crosslinking density increases too much and the mechanical strength decreases, both of which are unfavorable. Also, if the proportion of the diamino compound is less than 5 parts per 100 parts of the imide-modified epoxy resin, the imide-modified epoxy resin will not be cured sufficiently, and if it is more than 100 parts, the crosslinking density of the imide-modified epoxy resin will become too high. , both are unfavorable. In the production method of the present invention, the imide ring-containing dicarboxylic acid compound used in the production of the imide-modified epoxy resin, which is a component of the heat-resistant resin composition, has the general formula: (wherein R ₁ is an aliphatic or aromatic aminocarboxylic acid residue) or the general formula: Examples include imidocarboxylic acid compounds represented by the formula (wherein R ₂ is an aliphatic or aromatic diamino residue). In addition, examples of polyfunctional epoxy compounds used in the production of imide-modified epoxy resins include bisphenol A diglycidyl ether type Epicote 826, Epicote 827, Epicote
828 (all epoxy resins manufactured by Ciel Chemical, trade names), GY-252, GY-260 (all epoxy resins manufactured by Ciba Geigy, trade names), DER330,
DER331, DER332 (both epoxy resins manufactured by Dow Chemical Company, trade names), novolac type
DEN431, DEN438 (all epoxy resins manufactured by Dow Chemical, trade name), ECN1273 (epoxy resin manufactured by Ciba Geigy, trade name), aliphatic type OY-179 (epoxy resin manufactured by Ciba Geigy, trade name), etc. Examples include epoxy resins. In the production method of the present invention, examples of diamino compounds used in the heat-resistant resin composition include 4,
4'-diaminodiphenylmethane, 4,4'-diaminodiphenyl ether, 4,4'-diaminodiphenyl sulfone, 3,3'-diaminophenyl sulfone, 2,4-tolylenediamine, 2,6- Examples include tolylene diamine and hexamethylene diamine. Examples of polyfunctional bismaleimide compounds include N,N'-(methylenedi-p-phenylene) dimaleimide, N,N'-(oxydi-
p-phenylene) dimaleimide, N, N'-2,
4-Tolylene dimaleimide, N,N'-2,6-
Examples include tolylene dimaleimide, N,N'-m-xylylene dimaleimide, N,N'-p-xylylene dimaleimide, and N,N'-hexamethylene dimaleimide. However, the prepared heat-resistant resin composition is dissolved in an organic solvent such as dioxane, methyl ethyl ketone, N,N-dimethylacetamide, N,N-dimethylformamide, N-methylpyrrolidone, etc., and applied or impregnated onto a substrate. . The base material used in the manufacturing method of the present invention requires that the prepreg insulator has high mechanical strength (can be wound into a coil, etc.), is compatible with the prepreg resin, and has thermal and electrical properties after curing. It is preferable to heat-fuse laminated mica paper and aromatic polyamide paper containing 1 to 5% of polymer fibrils as a fusing agent. A base material having a two-layer structure bonded together by bonding is used. Regarding the composition ratio of laminated mica paper and aromatic polyamide paper in the base material, from the viewpoint of the mechanical strength of the resulting heat-resistant prepreg insulator and the various properties of the cured product of the heat-resistant prepreg insulator, laminated mica paper and aromatic polyamide paper are preferred.
For each 100 parts, 20 to 120 parts of aromatic polyamide paper are used. If the composition ratio of aromatic polyamide paper in the base material is less than 20 parts per 100 parts of laminated mica paper, the mechanical strength as a prepreg insulator will be poor, and cracks will occur when wound around a coil etc., making it unsuitable for practical use. Moreover, if it is larger than 120 parts, the base materials will not be firmly bonded when heated and cured after being wound around a coil, etc., which are both undesirable. In the production method of the present invention, the laminated mica paper used includes the laminated mica paper containing 1 to 5% of polymer fibrils as a fusion agent as described above, and representative examples thereof include, for example, Examples include laminated mica paper made by dispersing 30 to 5000 μm mica foil and polymer fibrids in water and making paper using a circular wire or fourdrinier paper machine. Examples of the polymer fibrils contained in the laminated mica paper as a fusing agent include short fibers (ie, fibrids) of aromatic polyamide, polyacrylonitrile, and the like. The content of polymer fibrids in the laminated mica paper is 1 to 5%, which improves the impregnation properties of the heat-resistant resin composition and the fusion properties with the aromatic polyamide paper, and improves the electrical properties. A laminated mica paper is obtained which gives a cured product with good mechanical properties. When the content of polymer fibrids in the laminated mica paper is less than 1%, it becomes difficult to thermally fuse it with aromatic polyamide paper;
When the amount is larger than this, the impregnating properties of the heat-resistant resin composition deteriorate, and as a result, the electrical properties and mechanical properties of the resulting cured product deteriorate, both of which are unfavorable. In the production method of the present invention, the aromatic polyamide paper to be heat-sealed to the laminated mica paper is, for example, isophthalic acid-m-phenylenediamine copolymer, terephthalic acid-p-phenylenediamine copolymer, etc. For example, aramid paper (manufactured by Mitsubishi Paper Mills, trade name) and Nomex paper (manufactured by DuPont, trade name) are examples. However, in the production method of the present invention, the heat-resistant resin is attached to a base material formed into a two-layer structure by heat-sealing laminated mica paper containing 1 to 5% of polymeric fibrils as a fusing agent and aromatic polyamide paper. A heat-resistant prepreg insulator is produced by applying or impregnating a solution of the composition in an organic solvent and then heating and drying the composition to form a semi-cured state. The resulting heat-resistant prepreg insulator has a long shelf life, high mechanical strength, and will not crack or wrinkle when wound into a coil or the like. In the manufacturing method of the present invention, the amount of the heat-resistant resin composition applied or impregnated onto the base material is 2 to 120 g per 100 g of the base material, thereby improving the fusion properties. A heat-resistant prepreg insulator is obtained which provides a cured product with good electrical and mechanical properties. The amount of the heat-resistant resin composition applied is 2g per 100g of the base material.
If the amount is less than 120 g, the heat-resistant prepreg insulation obtained will have insufficient fusion properties, and if it is more than 120 g, the tightness will be poor, both of which are undesirable. In addition, the heating and drying conditions for the substrate coated or impregnated with the organic solvent solution of the heat-resistant resin composition include a drying temperature of 60 to 350°C and a drying time of 0.1 to 60 minutes. A heat-resistant prepreg insulator is obtained that provides a cured product with excellent properties and heat resistance. When the drying temperature is higher than 350℃ and the drying time is longer than 60 minutes, the heat-resistant prepreg insulation will harden too much, resulting in cracks and wrinkles after being wound into a coil.
If the fusion is insufficient, and the drying temperature is lower than 60°C and the drying time is shorter than 0.1 minute, the solvent will not evaporate sufficiently, resulting in high stickiness and poor workability as a prepreg, both of which are undesirable. . However, the heat-resistant prepreg insulator that can be obtained is
After being wound around a conductor such as a coil, it is heated and pressurized to form a cured product. The resulting cured product has excellent heat resistance, particularly excellent electrical and mechanical properties at high temperatures, and can withstand long-term use at high temperatures. Next, the manufacturing method of the present invention will be specifically explained with reference to Examples and Comparative Examples. Example 1 DER332 (mentioned above,
Epoxy equivalent: 170) Chemical formula as a dicarboxylic acid compound having 170g (1 equivalent) and an imide ring: Using 68.3g (equivalent: 0.25) of the imidocarboxylic acid compound shown by and 0.20g of benzyltrimethylammonium chloride as a curing catalyst,
The reaction was carried out at 180°C for 1 hour to obtain an imide-modified epoxy resin. Next, N,N′- was added to the obtained imide-modified epoxy resin as a polyfunctional bismaleimide compound.
(methylene di-p-phenylene) dimaleimide 250
g and 100 g of 4,4'-diaminodiphenylsulfone as a diamino compound were added to prepare a heat-resistant resin composition. This heat-resistant resin composition was dissolved in a mixed solvent consisting of dioxane and N,N-dimethylacetamide (weight ratio, 1:1) to obtain an organic solvent solution of the heat-resistant resin composition. Next, aromatic polyamide paper [manufactured by Mitsubishi Paper Mills Co., Ltd., thickness: 0.1 mm] and laminated mica paper [polymer fibrid content: 3%, polymer fibrid component: isophthalic acid-diaminodiphenylmethane copolymer] Combined (polyamide), thickness: 0.1 mm] (weight ratio per 1 ^m2 : aromatic polyamide paper/laminated mica paper = 20/100) is heat fused to create a two-layer structure heat-resistant mica paper (i.e. base material) Then, an organic solvent solution of the heat-resistant resin composition was applied to this base material at a ratio of 80 g of the heat-resistant resin composition per 100 g of the base material, and the temperature was 120°C.
A semi-cured heat-resistant prepreg sheet was produced by drying for 30 minutes. In order to understand the mechanical properties of the heat-resistant prepreg sheet obtained, four heat-resistant prepreg sheets cut out to 25 mm x 25 mm were stacked between 25 mm x 25 mm iron blocks, and the temperature was 200°C and the pressure was 10 kg/kg. ^cm2 ,
A sample was prepared by hot pressing under conditions of a pressing time of 30 minutes, and the adhesive strength of the obtained heat-resistant prepreg sheet was measured using this sample. The measurement results are shown in Table 1. The adhesive strength was measured using an Instron tensile tester at a temperature of 25° C. for a selected sample (initial stage) and a sample (after aging) obtained by heat aging the sample at 220° x 20 days. The obtained heat-resistant prepreg sheet is 2mm x
A bundle of 10 formal rectangular copper wires of 5 mm x 500 mm was wound 4 times in wrapper winding (that is, sushi winding) on a coil conductor, and then the temperature was 200°C, the pressure was 10 Kg/cm ² , and the pressure was applied for 30 hours. An insulated coil with an insulating layer thickness of 0.2 mm was manufactured by hot pressing under the conditions of 10 minutes, and the electrical properties [dissipation tangent (tan δ) temperature characteristics, breakdown voltage] and appearance quality of this insulated coil were evaluated. It was measured. The measurement results are shown in Table 1. The dielectric loss tangent temperature characteristics were measured using the high-voltage shearing bridge method at a measurement voltage of 0.5 kV at temperatures of 20°C and 200°C (using a shearing bridge manufactured by Yokogawa Electric Corporation). . An insulated coil with a dielectric breakdown voltage (initial stage) and an insulated coil (after deterioration) subjected to thermal deterioration treatment at 220°C for 20 days are heated to a temperature of 25°C.
Measurements were made in oil at a constant pressure increase rate of 1 kV/sec (using a withstand voltage test device manufactured by Aikoku Denki Co., Ltd.).
In addition, the appearance of the insulated coil was evaluated by visual observation. Example 2 Aromatic polyamide paper [manufactured by Mitsubishi Paper Mills, thickness:
0.1 mm] and laminated mica paper [Polymer fibrids content: 5%, Polymer fibrs constituents:
Isophthalic acid-diaminodiphenylmethane copolymer (polyamide), thickness: 0.3 mm] (weight ratio per 1 ^m2 : aromatic polyamide paper/laminated mica paper =
20/100) was thermally fused to obtain a base material with a two-layer structure. A semi-cured heat-resistant prepreg sheet was then produced in the same manner as in Example 1, except that the obtained two-layer structure base material was used, and the adhesive strength of the thus-obtained heat-resistant prepreg sheet was measured. The measurement results are shown in Table 1. The thickness of the insulating layer was 0.2 mm in the same manner as in Example 1 except that the obtained heat-resistant prepreg sheet was used.
An insulated coil was manufactured, and the electrical characteristics and appearance of the obtained insulated coil were measured. The measurement results are shown in Table 1. Example 3 Aromatic polyamide paper [manufactured by Mitsubishi Paper Mills, thickness:
0.1 mm] and laminated mica paper [Polymer fibrids content: 1%, Polymer fibrs constituents:
Acrylonitrile-methyl methacrylate copolymer, thickness: 0.1 mm] (weight ratio per 1 m ² : aromatic polyamide paper/laminated mica paper = 60/60) was heat-fused to obtain a base material with a two-layer structure. A semi-cured heat-resistant prepreg sheet was then produced in the same manner as in Example 1, except that the obtained two-layer structure base material was used, and the adhesive strength of the thus-obtained heat-resistant prepreg sheet was measured. The measurement results are shown in Table 1. The thickness of the insulating layer was 0.2 mm in the same manner as in Example 1 except that the obtained heat-resistant prepreg sheet was used.
An insulated coil was manufactured, and the electrical characteristics and appearance of the obtained insulated coil were measured. The measurement results are shown in Table 1. Example 4 190 g (1 equivalent) of Epicote 828 (mentioned above, epoxy equivalent: 190) as a polyfunctional epoxy compound and the chemical formula as a dicarboxylic acid compound having an imide ring: Using 51.9 g (equivalent weight: 156) of the imidocarboxylic acid compound shown by and 0.20 g of benzyltriethylammonium chloride as a curing catalyst,
The reaction was carried out at 160°C for 1.5 hours to obtain an imide-modified epoxy resin. Next, 200 g of polyphenylmethylene polymaleimide as a polyfunctional bismaleimide compound and 4,4'-diaminodiphenylmethane as a diamino compound were added to the obtained imide-modified epoxy resin.
50g of each was added to prepare a heat-resistant resin composition. This heat-resistant resin composition was dissolved in N,N-dimethylacetamide to obtain an organic solvent solution of the heat-resistant resin composition. Then, a semi-cured heat-resistant prepreg sheet was produced in the same manner as in Example 1, except that the organic solvent solution of the obtained heat-resistant resin composition and the same two-layer base material as used in Example 3 were used. did. The adhesive strength of the obtained heat-resistant prepreg sheet was measured in the same manner as in Example 1. The measurement results are shown in Table 1. The thickness of the insulating layer was 0.2 mm in the same manner as in Example 1 except that the obtained heat-resistant prepreg sheet was used.
An insulated coil was manufactured, and the electrical characteristics and appearance of the obtained insulated coil were measured. The measurement results are shown in Table 1. Comparative example 1 DEN438 (mentioned above, epoxy equivalent: 180) 60g,
40 g of ECN1273 (mentioned above, epoxy equivalent: 225) and 3 g of boron trifluoride monoethylamine complex salt were dissolved in a mixed solvent consisting of 45 g of acetone and 55 g of toluene to obtain an organic solvent solution of an epoxy resin composition. Next, an organic solvent solution of the epoxy resin composition was applied to the same two-layer structure substrate used in Example 1 at a ratio of 80 g of the epoxy resin composition per 100 g of the substrate, and the mixture was heated at a temperature of 100° C. for 5 minutes and then heated at a temperature of 110° C. 8 degrees Celsius
A prepreg sheet was produced by drying for a minute. Then, the adhesive strength of the prepreg sheet obtained was measured in the same manner as in Example 1. The measurement results are shown in Table 1. An insulated coil having an insulating layer thickness of 0.2 mm was manufactured in the same manner as in Example 1 except that the obtained prepreg sheet was used, and the electrical characteristics and appearance quality of the obtained insulated coil were measured. . The measurement results are shown in Table 1. Comparative Example 2 The organic solvent solution of the epoxy resin composition obtained in Comparative Example 1 was applied at a ratio of 80 g of the epoxy resin composition per 100 g of aromatic polyamide paper (manufactured by Dupoupon, trade name "Nomex Paper", thickness: 0.1 mm). The prepreg sheet was then dried at a temperature of 105°C for 10 minutes to produce a prepreg sheet. The adhesive strength of the prepreg sheet thus obtained was then measured in the same manner as in Example 1. The measurement results are shown in Table 1. An insulated coil having an insulating layer thickness of 0.2 mm was manufactured in the same manner as in Example 1 except that the obtained prepreg sheet was used, and the electrical characteristics and appearance quality of the obtained insulated coil were measured. . The measurement results are shown in Table 1.

[Table] (Note) Content of heat-resistant resin composition or epoxy resin composition in prepreg sheet.
Examples 5 to 7 The heat resistant prepreg sheets produced in Examples 1 to 3 were cut to a width of 25 mm to obtain heat resistant prepreg tapes. Next, 2mm x 2mm of selected heat-resistant prepreg tape
A bundle of 10 formal rectangular copper wires of 5 mm x 500 mm was wound 5 times in half laps on a coil conductor, and then heated at 170°C for 4 hours and then at 200°C for 12 hours to determine the thickness of the insulating layer. Insulated coils with 0.2 mm were each produced. The electrical characteristics of the obtained insulated coils were measured in the same manner as in Example 1. The measurement results are shown in Table 2. The appearance of the obtained insulated coils was good, and no flaking or peeling was observed.

[Table] Tables 1 and 2 show that the heat-resistant prepreg insulator of the present invention has an insulating structure with superior heat resistance, electrical properties, and mechanical properties compared to the prepreg sheet obtained in the comparative example. Giving is clear. Furthermore, the insulated coil obtained using the heat-resistant prepreg insulator according to the present invention had an extremely good appearance, and no flaking or peeling was observed. The heat-resistant prepreg insulator of the present invention is heated and press-formed or heat-treated after being wound around a conductor such as a coil, so an insulating structure with excellent properties as described above is obtained, making it extremely advantageous industrially. It is.

Claims (1)

[Scope of Claims] 1. The base material is a two-layer structure made by thermally fusing laminated mica paper containing 1 to 5% by weight of polymeric fibrils as a fusing agent and aromatic polyamide paper,
A method for producing a heat-resistant prepreg insulator, which is coated with or impregnated with a heat-resistant resin composition comprising an imide-modified epoxy resin, a diamino compound, and a polyfunctional bismaleimide compound, and then heat-dried to a semi-cured state. 2. The production method according to claim 1, wherein the composition ratio of the laminated mica paper and the aromatic polyamide paper is 20 to 120 parts by weight of the aromatic polyamide paper per 100 parts by weight of the laminated mica paper.