JPS625453B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a photocurable prepreg. More specifically, it relates to photo-curable prepreg, which is flexible in a semi-cured state and easily hardens and becomes fixed when exposed to light, for interlayer insulation of coils for electrical equipment, or insulation of slots, leads, etc. be. The method of insulating coils for electrical equipment using semi-cured prepreg insulating sheets or prepreg insulating tape 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 this prepreg, 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 of the cured product. . In addition, the base material of prepreg is inorganic fiber base material such as glass cloth,
Organic fiber base materials such as polyethylene terephthalate cloth, heat shrink films, paper, mica sheets, etc. are used. However, this semi-cured prepreg must be heated when curing, so it cannot be used for adherends that change or decompose when heated, and The adhesion and moldability of the adherend were often extremely uncertain due to tape displacement due to deformation of the adherend and flow of the semi-cured resin. In addition, in the case of adherends with large heat capacity, the temperature required for the curing reaction (usually 100 to 150
It took a considerable amount of time for the temperature to rise to .degree. The present inventors have conducted intensive research to eliminate the above-mentioned drawbacks and provide a photocurable prepreg that is semi-cured, flexible, and easily cures and becomes fixed when cured by light irradiation. , we have completed the present invention. That is, the present invention uses a multilayer structure of laminated mica paper containing polymeric fibrils as a fusion agent and aromatic polyamide paper as a base, which is obtained by reacting an imide ring-containing dicarboxylic acid compound and an epoxy compound. The invention relates to a photocurable prepreg obtained by coating or impregnating an imide-modified epoxy resin with a photocurable resin composition obtained by reacting an unsaturated basic acid, and then heating and drying the base material, the photocurable prepreg being heat-dried. By using a photocurable prepreg made of a specific base material and a photocurable resin composition when insulating coils, etc., heating is not necessarily required as in the case of using conventional prepreg. It cannot be used for adherends that change in quality or decompose when heated, and may cause deformation of the adherend due to heating or slippage of the tape due to the flow of the semi-cured resin. The above-mentioned drawbacks such as extremely uncertain fixation formability have been completely eliminated, and it is semi-cured and flexible, and can be easily cured and fixed by light irradiation without heating during curing. A very noticeable effect is produced. Furthermore, in this photocurable prepreg, there is no need to heat the adherend to a temperature necessary for a thermosetting reaction, and the curing time can be extremely shortened, resulting in an energy saving effect. Additionally, the prepreg of the present invention cures when exposed to a source of ultraviolet light (e.g. sunlight, low to high pressure mercury lamp, xenon lamp, etc.), and permanently crosslinks when not exposed to ultraviolet light. It has the characteristics of excellent storage stability and a long shelf life without causing any damage. Further, by introducing an imide ring into the photocurable resin composition, a prepreg with excellent heat resistance can be obtained. On the other hand, the base material used here, which has a multilayer structure of laminated mica paper containing polymeric fibrids as a fusion agent and aromatic polyamide paper, has a feature of higher heat resistance than conventional polyester mat, etc. The photocurable prepreg of the present invention obtained from this and the photocurable resin composition provides an insulator with high heat resistance. The photocurable resin composition used in the photocurable prepreg of the present invention is an imide ring-containing dicarboxylic acid 1
An imide-modified epoxy resin is obtained by reacting 1.2 to 5 equivalents of an epoxy resin with respect to the equivalent, and the imide-modified epoxy resin and an unsaturated basic acid are reacted as necessary.
It can be easily obtained by carrying out a heating reaction in the presence of an esterification catalyst, a vinyl polymerization inhibitor, a solvent, and a vinyl monomer. The imide ring-containing dicarboxylic acid compound used here includes, for example, the general formula (In the formula, R ₁ represents an aliphatic or aromatic diamino residue, R ₂ represents an aliphatic or aromatic aminocarboxylic acid residue, and R ₃ represents an aliphatic or aromatic tetracarboxylic acid residue) Examples include the expressed compounds. 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, and Epicote 828 (all epoxy resins manufactured by Shinil Chemical Co., Ltd., trade names). , G.Y.
-252, GY-260 (all epoxy resins manufactured by Ciba Geigy, trade names), DER330, DER331,
DER332 (all epoxy resins manufactured by Dow Chemical Company, trade name), novolac type DEN431,
Examples include DEN438 (all epoxy resins manufactured by Dow Chemical Company, trade name) and aliphatic type CY-179 (epoxy resin manufactured by Ciba Geigy Company, trade name). Note that when the amount of the epoxy resin blended is less than 1.2 equivalents, the molecular weight of the resin obtained becomes large, the solubility decreases, and the softening point increases, resulting in poor workability. On the other hand, if it exceeds 6 equivalents, the resulting resin will not have satisfactory heat resistance, so it is desirable to keep it within the above range. Furthermore, examples of unsaturated basic acids that can be used in the present invention include acrylic acid, methacrylic acid, sorbic acid, and cinnamic acid. In addition, in the reaction of polyfunctional epoxy compounds and unsaturated basic acids, quaternary ammonium salts, tertiary
By using a catalyst such as a grade amine, the reaction can be carried out more smoothly. Hydroquinone, parabenzoquinone, hydroquinone monomethyl ether, phenothiazine,
Thiosemicarbazide, acetone thiocarbazone copper salt, etc. can be added usually in a range of 0.001 to 1.0% by weight. Furthermore, curing can be further facilitated by adding 0.1 to 5 parts by weight of the following photosensitizers to 100 parts by weight of the photocurable resin composition. . Examples of the photosensitizer include benzoin and its derivatives (for example, benzoin methyl ether,
ethyl ether, isopropyl ether, etc.), quinone compounds such as anthraquinone and naphthoquinone, organic sulfur compounds such as diphenyl sulfide, peroxides such as benzoin peroxide, and azobisisobutyronitrile. These include nitrogen compounds and photocyclic dyes (for example, methylene blue, p-toluenesulfonate ion, etc.). Furthermore, if necessary, a vinyl monomer may be added to the photocurable resin composition. Examples of the vinyl monomer include styrene, vinyltoluene, diallyl phthalate, diallyl isophthalate, triallyl isocyanurate, triallyl cyanurate, triallyl trimellitate, vinyl acetate, (meth)acrylic acid esters, and (meth)acrylic acid esters. There are acid esters, etc., and the amount of these vinyl monomers is 20% of the total.
(wt%, the same applies hereinafter) or less is desirable. That is, if it exceeds 20%, the adhesiveness of the prepreg becomes high, resulting in poor workability and storage stability. In the photocurable prepreg of the present invention, a new base material having a multilayer structure in which laminated mica paper containing polymeric fibrils and aromatic polyamide paper are bonded together by heat fusion as a fusion agent is used. The composition ratio of laminated mica paper and aromatic polyamide paper in the base material is 100 parts of laminated mica paper to 20 parts of aromatic polyamide paper, from the viewpoint of the mechanical strength of the resulting photocurable prepreg and various properties of the cured product.
~120 parts is preferred. If the composition ratio of aromatic polyamide paper in the base material is less than 20 parts per 100 parts of aggregate mica, the mechanical strength as a prepreg will be poor,
If it is wound around a coil etc., cracks will occur and it cannot be used for practical purposes, and if it is larger than 120 parts, it tends to not adhere firmly between the base materials when it is heated and hardened after being wound around a coil etc. Both are unfavorable because they can be seen. As mentioned above, the laminated mica paper used in the photocurable prepreg of the present invention includes laminated mica paper containing polymer fibrils as a fusion agent, and representative examples thereof include:
For example, mica foil of 30 to 5000 μm and polymeric fibrids are dispersed in water, and paper is made using a circular wire or Fourdrinier paper machine to obtain laminated mica paper. Examples of the polymer fibrils contained in the laminated mica paper as a fusing agent include short fibers (ie, fibrids) of aromatic polyamide, polyacrylontrile, and the like. The content of polymer fibrids in the laminated mica paper is usually 1 to 10%, more preferably 1 to 5%.
As a result, a laminated mica paper can be obtained that provides a cured product with good impregnation properties with the photocurable resin composition and good fusion properties with the aromatic polyamide paper. If the content of polymer fibrids in the laminated mica paper is less than 1%, it will be difficult to heat-fuse it with aromatic polyamide paper, and if it is more than 10%, the photocurable resin composition will Impregnating properties deteriorate, and as a result, the electrical properties and mechanical properties of the resulting cured product deteriorate, both of which are unfavorable. In the photocurable prepreg 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-γ-phenylenediamine copolymer, etc. Examples of such paper include aramid paper (Mitsubishi Paper Mills Co., Ltd.) and Nomex paper (DuPont Co., Ltd., trade name). Therefore, the photocurable prepreg of the present invention is made by applying an organic solvent solution of the photocurable resin composition to a base material having a multilayer structure of laminated mica paper and aromatic polyamide paper containing polymeric fibrils as a fusion agent. After coating or impregnating, it is heated and dried to obtain a semi-cured product. The resulting photocurable prepreg has a long shelf life, high mechanical strength, and does not crack or wrinkle even when wound into a coil or the like. Furthermore, the conditions for heating and drying the base material coated or impregnated with the organic solvent solution of the photocurable resin composition are as follows:
A drying temperature of 50 to 200° C. and a drying time of 1 to 60 minutes is used, thereby obtaining a photocurable prepreg that provides a cured product with excellent electrical and mechanical properties. Drying temperature is higher than 200℃ and drying time is 60℃
If it is longer than 1 minute, the curing of the resulting photocurable prepreg progresses too much, resulting in wrinkles and cracks after being wound into a coil, and insufficient fusion properties. Furthermore, when the drying temperature is lower than 50° C. and the drying time is shorter than 1 minute, the volatilization of the solvent is insufficient and the adhesiveness becomes large, resulting in poor workability as a prepreg, and both are unfavorable. The resulting photocurable prepreg can be easily cured and fixed by irradiation with light without being heated after being wound around a conductor such as a coil, and has good heat resistance, mechanical properties, and electrical properties. Gives a cured product. Next, the present invention will be explained in more detail with reference to Examples. The imide ring-containing dicarboxylic acid compounds used in the examples of the present invention described below are shown below. Example 1 27.3 g (0.1 equivalent) of an imide ring-containing dicarboxylic acid compound represented by the structural formula IC-1 and 95 g (0.5
equivalent) and reacted at 150° C. for 1 hour using 0.01 g of benzyltriethylammonium chloride as a catalyst to obtain an imide-modified epoxy resin with an epoxy equivalent of 300. To 600 g of this imide-modified epoxy resin, 150 g of methacrylic acid was added and reacted at 130° C. for 2 hours to obtain an unsaturated polyester (A) with an acid value of 5. 0.8 g of benzoin ethyl ether was added to 100 g of the unsaturated polyester (A) obtained here to synthesize a photocurable resin composition. Next, aromatic polyamide paper (Mitsubishi Paper Mills Co., Ltd.: thickness
0.1 mm] and laminated mica paper [polymer fibrid content: 3%, composition of polymer fibrils: isophthalic acid-diaminodiphenylmethane copolymer (polyamide): thickness 0.1 mm] (weight ratio per 1 ^m2) : Aromatic polyamide paper/laminated mica paper = 20/
100) to obtain a two-layer structure heat-resistant mica paper (i.e. base material), apply the photocurable resin composition to this base material, and process at a temperature of 100°C for 30 minutes to produce a prepreg sheet. did. In order to understand the mechanical properties of this prepreg sheet, four photocurable prepreg sheets cut out to 25 mm x 25 mm were heated to about 80°C and exposed to a 2.5 KW mercury lamp for about 10 minutes. The adhesive strength of the cured sheet obtained using this sample was measured at a temperature of 20°C using an Instron tensile tester. In addition, the obtained photocurable prepreg sheet was
10 formal rectangular copper wires of mm x 5 mm x 500 mm
After winding the bundled coil conductor four times in a lapper winding (or sushi winding), the insulated coil was exposed to a 2.5 KW mercury lamp for 10 minutes while being heated to 80°C. tanδ) temperature characteristics,
dielectric breakdown voltage) was measured. The measurement results are shown in Table 1. In addition, the dielectric loss tangent temperature characteristics are obtained by measuring the voltage of the obtained insulated coil at temperatures of 20°C and 200°C.
Measurement was performed using the high-voltage Schering bridge method at 0.5 KV (using a Schering bridge manufactured by Yokogawa Electric Corporation). An insulated coil with a dielectric breakdown voltage (initial stage) and an insulated coil (after deterioration) subjected to heat aging treatment at 220°C for 20 days at a temperature of 25°C.
Measurement was carried out in oil at a constant pressure increase rate of 1 KV/sec (using a withstand voltage test device manufactured by Aikoku Denki Co., Ltd.). Example 2 Aromatic polyamide paper [manufactured by Mitsubishi Paper Mills, thickness 0.1
mm] and laminated mica paper, [Polymer fibrid content: 5%, Polymer fibrid constituents: Isophthalic acid-diaminodiphenylmethane copolymer (polyamide): Thickness 0.3 mm] (Weight per ¹ m2) Aromatic polyamide paper/laminated mica paper = 20/100)
were thermally fused to obtain a base material with a two-layer structure. In addition to using the obtained two-layer structure base material,
A semi-cured photocurable prepreg sheet was produced in the same manner as in Example 1, and the adhesive strength of the obtained photocurable prepreg sheet was measured. Further, an insulated coil was manufactured in the same manner as in Example 1 except that the obtained photocurable prepreg sheet was used, and the electrical properties of the obtained insulated coil were measured. The measurement results are shown in Table 1. Example 3 Aromatic polyamide paper [Mitsubishi Paper Mills, Ltd.: thickness 0.1
mm] and laminated mica paper [Content of polymer fibrils: 1%, Constituent components of polymer fibrils: Acrylonitrile-methyl methacrylate copolymer:
0.1 mm thick] (weight ratio per 1 m ² : aromatic polyamide paper/laminated mica paper = 60/60) was heat-sealed to obtain a base material with a two-layer structure. Next, a semi-cured photocurable prepreg sheet was 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 obtained photocurable prepreg sheet was determined. It was measured. Further, an insulated coil was manufactured in the same manner as in Example 1 except that the obtained photocurable prepreg sheet was used, and the electrical properties of the obtained insulated coil were measured. These results are shown in Table 1. Example 4 21.9 g (0.1 equivalent) of imide ring-containing dicarboxylic acid represented by IC-2 and Epicote 828, which is a bisphenol A type epoxy resin with an epoxy equivalent of 190.
(Ciel Chemical brand name) and 57.0 g (0.3 equivalents) of the mixture, and reacted at 150°C for 30 minutes using 0.02 g of benzyltriethylammonium bromide as a catalyst.
An imide-modified epoxy resin with an epoxy equivalent of 400 was obtained. 140 g of methacrylic acid was added to 800 g of this imide-modified epoxy resin and reacted at 120° C. for 2 hours to obtain an unsaturated polyester (B) with an acid value of 7. 0.5 g of benzoin ethyl ether was added to 100 g of the unsaturated polyester (B) obtained here to synthesize a photocurable resin composition. Next, a semi-cured photocurable prepreg sheet was produced in the same manner as in Example 1, except that the obtained photocurable resin composition and the same two-layer base material as used in Example 3 were used. did. The adhesive strength of the obtained photocurable prepreg sheet was measured in the same manner as in Example 1. The measurement results are shown in Table 1. Comparative example 1 DEN438 (Dow Chemical Co., Ltd.: Epoxy equivalent
160) 60g and 40g of ECN1273 (Ciba Gaiki Co., Ltd. epoxy equivalent weight 225) and 3g of boron monoethylamine complex salt and acetone/toluene (45/55)
An organic solvent solution of the epoxy resin composition was obtained. Next, the epoxy resin composition was applied to the same two-layer structure base material used in Example 1, and the temperature was increased.
A prepreg sheet was produced by drying at 100°C for 5 minutes and then at 110°C for 8 minutes. Then, the adhesive strength of the obtained prepreg sheet was measured in the same manner as in Example 1. The measurement results are shown in Table 1. An insulated coil was manufactured in the same manner as in Example 1 except that the obtained prepreg sheet was used, and the electrical properties and appearance of the obtained insulated coil were measured. The measurement results are shown in Table 1. Comparative Example 2 An organic solvent solution of the epoxy resin composition obtained in Comparative Example 1 was applied to aromatic polyamide paper (manufactured by DuPont, trade name "Nomex Paper": thickness 0.1 mm),
A prepreg sheet was produced by drying at a temperature of 105°C for 10 minutes. Then, the adhesive strength of the obtained prepreg sheet was measured in the same manner as in Example 1. Further, an insulated coil was manufactured in the same manner as in Example 1 except that the obtained prepreg sheet was used, and the electrical properties and appearance quality of the obtained insulated coil were measured. The measurement results are shown in Table 1.

[Table] In the photocurable prepreg of the present invention, by winding it around a conductor such as a coil and then irradiating it with light, an insulating structure excellent in the above properties can be easily obtained, which is extremely advantageous industrially. It is.

Claims (1)

[Claims] 1. A base material made by heat-sealing a laminated mica paper containing polymeric fibrils as a fusion agent and an aromatic polyamide paper, by reacting an imide ring-containing dicarboxylic acid compound and an epoxy compound. A photocurable prepreg made into a semi-cured state by coating or impregnating a photocurable resin composition obtained by reacting the resulting imide-modified epoxy resin with an unsaturated basic acid. 2. The photocurable prepreg 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 based on 100 parts by weight of the laminated mica.