Thermosetting resin composition, electrically insulated coil, electric rotating machine and method for producing same

Abstract: A highly thermal-conductive and thermal-resistant electrically insulated coil with less outflow of a thermosetting resin composition can be produced, to provide a small-scale, light-weight rotating machine with high power. The thermosetting resin composition comprising (a) a polyfunctional epoxy resin containing three or more p-(2,3-epoxypropoxy)phenyl groups and a group represented by the Chemical formula 1; or an epoxy resin with a naphthalene backbone, represented by the Chemical formula 3, 4 or 5 or an epoxy resin with an anthracene backbone, such as diglycidyl ether of anthracene diol and triglycidyl ether of anthracene triol; (b) a bifunctional epoxy resin containing two p-(2,3-epoxypropoxy)phenyl groups; (c) an acid anhydride curing agent; and (d) a metal acetonate curing catalyst represented by the Chemical formula 2 at 0.1 to 5 parts by weight per 100 parts by weight of the epoxy resins. In accordance with the present invention, a highly thermal-conductive and thermal-resistant electrically insulated coil with less outflow of the thermosetting resin composition can be produced, to provide a small-scale, light-weight rotating machine armature with high power.

Description: BACK GROUND OF THE INVENTION The present invention relates to an electrically insulated coil , having a high shear strength and high heat resistance and high voltage , wherein a thermosetting resin composition of a repeatedly usable one-component epoxy resin is used; an electric rotating machine using the coil and also relates to a method for producing a total impregnated rotating coil. Demands for making high-voltage rotating machines such as electric vehicles and induction motors for general industries a small scale and a light weight and a low cost, have been increasingly escalated. The methods for manufacturing the stator coil and rotor of such high-voltage rotating machines are broadly grouped as follows;(1) single prepreg process;after prepereg mica tapes are wound around a stack of insulated conductors, prepreg mica tape around a conductor the stack is heated and the resin is hardened. the cured electrical insulating coil is placed into an iron core slot; single inpregnation process ; after insulating mico tapes have bee wound around a stack of insulated conductors, the stack is impregnated with thermosetting resin composition in a tank, and the resulting stack is heated and the resin is , and the resulting stack is heated and the resin is Thecured elctrically insulated coil is placed into an iron core slot; (3) an total impregnation process; after the insulating mica tapes have been wound around a stack of insulated condoctors,the stack is placed into an iron core slot, inserting a wedge into the external circumference groove of the iron core slot to connect the electrical insulating coil to the external end part of the iron core, and impregnting with thermosetting resiu composition in a tank, and curing the electrical insulating coil and the iron core slot at their integrated state with a thermosetting resin composition. In the stator of the total impregnation type, the iron core and the electrically insulated coil are integrated together because the cured matter of the impregnating thermosetting resin composition is filled in the space between the electrically insulated coil and the iron core slot. Therefore, the heat conductivity between the electrically insulated coil and the iron core is so high that good cooling performance can be procured and the process can be simplified, advantageously from the respect of production of small-scale and light-weight equipment at low cost. Thus, such process is now under the way of the first choice as the insulating process from small scale to medium scale of high voltage electric rotating machines of high-pressure revolving. Thermosetting resin compositions for impregnating electrical insulating coils to be used for the single impregnation process or total impregnation process are required to satisfy the conditions as follows; 1. the compositions should have a low viscosity (at 1 Pa·s (10 poise) or less during impregnation) so as to readily impregnate such electrically insulated coils; 2. the compositions should never generate volatile substances so as to avoid the occurrence of void (space) at a course of heating and curing; 3. the pot life, namely usable time is as long as 25 days or more; 4. the heating and curing time is short; 5. the electrical and mechanical performance is great; 6. Compatibility with insulating tape base material is comfortable; and 7. the cured compositions are highly thermally resistant; in other words, the cured compositions should have short-term and long-term thermal deterioration characteristics above 155 °C. A thermosetting resin composition principally comprising an acid anhydride and an epoxy resin has been used from the respect that as a thermosetting resin composition for impregnating electrically insulated coils of rotating mavhine , the composition has a low viscosity with ready workability and handleability during impregnation and exerts a variety of great performance after curing. Manufacture of electrically insulated coils requires more than 1000kg of impregnating thermosetting resin composition in order to immerse the whole coils. However, the amount in consumption at one impregnation is at most at about several %, so the remaining amount should be recovered, followed by fresh addition thereof at the amount corresponding to the consumption, so as to the composition in repetition. Although such thermosetting resin composition of an acid anhydride-hardening epoxy resin has a longer usable time, the resin composition requires a catalyst because of poor curing profile. Generally, however, direct addition of a curing catalyst into a thermosetting resin composition elevates the viscosity of the thermosetting resin composition during the impregnation, storage. Thus, the composition falls into an unusable state in several days. Therefore, so-called coating process to deposit a curing catalyst onto an insulating tape base material, as described in Japanese Patent Laid-open No. Sho 62-1124452, has been selected generally. If an electrically insulated coil is prepared by the coating process of a curing catalyst, the amount of the curing catalyst tends to be so less in the thermosetting resin composition impregnated into the space between an iron core slot and the electrically insulated coil, in the thermosetting resin composition at a part apart from the insulating tape base material layer and with a lower curing catalyst level , and in the thermosetting resin composition on the surface layer of the electrical insulating coil, that the curing therein is insufficient. Therefore, satisfactory performance cannot be attained eventually. Because the variation of the curing catalyst level is large in the insulating tape base material, the variation of the performance of the insulating layer cannot be reduced. Research works about so-called latent curing catalysts, which are stable at ambient temperature but rapidly effect curing on heating, have been conducted actively; therefore, proposals have been made as to what will be described below; metal imidazolate, as described in Japanese Patent Laid-open No. Sho 48-79300; tetra-onium salt, as described in Japanese Patent Laid-open No. Sho 50-110500; an addition product of imidazole and a first transition metal coordination compound, as described in Japanese Patent Laid-open No. Sho 50-11298; arsonium salt, as described in Japanese Patent Laid-open No. Sho 50-117898; chromium (III) chelate, as described in Japanese Patent Laid-open No. Sho 51-8400; metal acetylacetonate, as described in Japanese Patent Laid-open No. Sho 52-130899; organosiloxane compounds and aluminium acetylacetonate, as described in Japanese Patent Laid-open Nos. Sho 53-125500 and 56-4625; a reaction product from the reaction of a metal acetylacetonate and an acid anhydride with polyethylene glycol monoalkyl ether; a reaction product from the reaction of a metal acetylacetonate and an acid anhydride with polyethylene glycol monoalkyl ether , as described in Japanese Patent Laid-open No. Sho 60-108418; a reaction product from the reaction of a metal acetylacetonate and an acid anhydride with an aliphatic alcohol, as described in Japanese Patent Laid-open No. Sho 61-4722; occult hydrazine curing catalysts as described in Japanese Patent Laid-open No. Sho 62-270616; an latent curing catalyst produced by the reaction of an epoxy resin compound with dialkylamine to prepare an addition compound, which is then pulverized in powder, as described in Japanese Patent Laid-open No. Sho 64-40516; and the use of a borotrifluoride complex compound and a microcapsule-type latent curing agent in combination, as described in Japanese Patent Laid-open No. Hei 3-281625. However, these catalysts have not necessarily been satisfactory in practical sense, because not any of these catalysts can have the stability and curing performance together. SURMMARY OF THE INVENTION In such circumstances, the present invention has been attained. The object is to provide a thermosetting resin composition of a one-component type acid anhydride-hardening epoxy resin; and an electrically insulated coil, a stator and a rotating armature with a higher shear strength and high heat resistance and high , using the same. Attention has been focused on the non-solvent type resin composition with higher fluidity, as described in Japanese Patent Laid-open No. Sho 52-130899. More specifically, as an impregnating resin for an electrically insulated coil of the stator from an total impregnation process, examination has been done about a non-solvent type resin composition being highly fluid with an initial viscosity below 0.350 Pa·s (350 cps) at 25 °C and containing (1). 100 parts by weight of an epoxy resin containing a first epoxy resin comprising diglycidyl ether of an aliphatic diol; and a second epoxy resin selected from the group consisting of a bisphenol type epoxy resin, bisphenol-F epoxy resin, novolak- epoxy resin, glycidyl ester epoxy resin, hydantoin epoxy resin, an alicyclic epoxy resin and a mixture thereof at a ratio of the number of epoxy groups of the first to the second epoxy resins of 1.0 : 0.0 to 4.0; (2). 25 to 200 parts by weight of an organic carboxylic anhydride; 3. 0.002 to 1.00 parts by weight of a metal acetylacetonate selected from the group consisting of chromium (III) acetylacetonate, titanyl acetylacetonate, aluminium (III) acetylacetonate, manganese (III) acetylacetonate, cobalt (II) acetylacetonate, cobalt (III) acetylacetonate, nickel (II) acetylacetonate, vanadium (III) acetylacetonate, zirconium (IV) acetylacetonate, sodium (I) acetylacetate, potassium (I) acetylacetate and a mixture thereof per 100 parts by weight of the epoxy resin. From any of the combinations used, consequently, poor curing performance, resin flow in the heating and curing course, poor electrical performance or insufficient curing has occurred, with the resultant no compatibility between the pot life and the curing performance. So as to elevate the curing performance, a metal acetylacetonate, a reaction product from the reaction of an acid anhydride with polyethylene glycol monoalkyl ether , and a reaction product from the reaction of a methyl acetylacetonate, an acid anhydride and an aliphatic alcohol, as described in Japanese Patent Laid-open Nos. Sho 60-108418 and 61-4722, have not been used satisfactorily. After a variety of investigations, consequently, it has been found that a specific epoxy resin with high reactivity and high heat resistance, if used as the aforementioned epoxy resin, can realize the compatibility between the pot life and the curing performance. Thus, the present invention has been achieved. The object of the present invention is to provide a highly reliable electrically insulated coil for electric appliances, characterized in that the impregnating varnish thereof has a longer pot life during the production of the electrically insulated coil and is capable of forming a uniform resin layer in the insulated coil with less flow of the impregnating varnish. BRIEF DESCRIPTION OF THE DRAWINGS [Fig.1] A view depicting the structure of the electrically insulated coil in accordance with the present invention. [Fig.2] An explanatory view depicting the temperature characteristics of the dielectric tangent of an electrically insulated coil of one example of the present invention. [Fig.3] An explanatory view depicting the heat-resistant life of an electrically insulated coil of one example of the present invention. [Fig.4] A view depicting the coil (stack of insulated layer) of the present invention. [Fig.5] An explanatory view depicting the cross section of the rotating electric stator of the present invention. [Fig.6] An explanatory view depicting the enlarged cross section of the rotating electric stator of Fig.5. [Fig.7] A view depicting the rotating machine of one example of the present invention. [Explanations of Symbols] 1. Conductor 2. Insulated layer 3. coil (stack of insulated layer) 4. Slot liner 5. Iron core 6. Wedge 7. Rotating electric stator 8. Armature coil of rotating electric machine A. Initial characteristic curve of electrically insulated coil of Example 1 B. Characteristic curve of the electrically insulated coil after 1,000-hr heating at 250 °C of Example 1. BRIEF DESCRIPTION OF THE PREFERRED EMBODIMENT The object of the present invention is attained by using as the impregnating varnish for electrically insulated coils, a thermosetting resin composition being at a viscosity of 0.5 Pa·s (5 poise) or more at 25 °C, preferably 10 poise or more at 25 °C and a viscosity of 0.5 Pa·s (5 poise) or less at 60 °C and comprising (a) a polyfunctional epoxy resin containing three or more p-(2,3-epoxypropoxy)phenyl groups and a group represented by the Chemical formula 1; or an epoxy resin with a naphthalene backbone , represented by the Chemical formula 3, 4 or 5 or an epoxy resin with an anthracene backbone such as diglycidyl ether of anthracene diol and triglycidyl ether of anthracene triol ; (b) a bifunctional epoxy resin containing two p-(2,3-epoxypropoxy)phenyl groups; (c) an acid anhydride curing agent; and (d) a metal acetonate curing catalyst represented by the Chemical formula 2 at 0.1 to 5 parts by weight per 100 parts by weight of the epoxy resins, wherein the ratio of the numbers of the epoxy groups used is 1 to 4, the ratio being represented by the following formula; Ratio of numbers of epoxy groups = {[molar number of (b) used] × [number of epoxy groups in 1 mole of (b)]} ÷ {[molar number of (a) used] × [number of epoxy groups in 1 mole of (a)] }. In the electrically insulated coils produced by the single impregnation process comprising impregnating and curing a electrically insulated coil with an insulating tape base material wound around a stack of insulated conductor formed into a defined coil shape with a thermosetting resin composition, and thereafter placing the coil into an iron core slot and the total impregnation process comprising incorporating a electrically insulated coil with an insulating tape base material wound around a stack of insulated conductor formed in a defined coil shape into an iron core slot, inserting a wedge into the external circumference groove of the iron core slot to connect the electrical insulating coil to the external end part of the iron core, and impregnating and curing the electrically insulated coil and the iron core slot at their integrated state with a thermosetting resin composition, wherein as the thermosetting resin composition, use is made of a thermosetting resin composition being at a viscosity of 0.5 Pa·s (5 poise) or more, preferably 1 Pa·s (10 poise) or more at 25 °C and a viscosity of 0.5 Pa·s (5 poise) or less at 60 °C and comprising (a) a polyfunctional epoxy resin containing three or more p-(2,3-epoxypropoxy)phenyl groups and a group represented by the Chemical formula 1; or an epoxy resin with a naphthalene backbone , represented by the Chemical formula 3, 4 or 5 or an epoxy resin with an anthracene backbone, such as diglycidyl ether of anthracene diol and triglycidyl ether of anthracene triol; (b) a bifunctional epoxy resin containing two p-(2,3-epoxypropoxy)phenyl groups; (c) an acid anhydride curing agent; and (d) a metal acetonate curing catalyst represented by the Chemical formula 2 at 0.1 to 5 parts by weight per 100 parts by weight of the epoxy resins, wherein the ratio of the numbers of the epoxy groups used is 1 to 4, the ratio being represented by the following formula; Ratio of numbers of epoxy groups = {[molar number of (b) used] × [number of epoxy groups in 1 mole of (b)]} ÷ {[molar number of (a) used] × [number of epoxy groups in 1 mole of (a)] }, whereby the electrical insulated coil can obtain high heat resistance and high thermal conductivity with less flow of the thermosetting resin composition. The present invention is summarized as follows. A first aspect of the present invention is an invention relating to a thermosetting resin composition being at a viscosity of 0.5 Pa·s (5 poise) or more, preferably 1 Pa·s (10 poise) or more at 25 °C and a viscosity of 0.5 Pa·s (5 poise) or less at 60 °C and comprising (a) a polyfunctional epoxy resin containing three or more p- (2, 3-epoxypropoxy)phenyl groups and a group represented by chemical formula (1); (b) a bifunctional epoxy resin containing two p-(2,3-epoxypropoxy)phenyl groups; (c) an acid anhydride curing agent; and (d) a metal acetonate curing catalyst represented by the Chemical formula 2 at 0.1 to 5 parts by weight per 100 parts by weight of the epoxy resins, wherein the ratio of the numbers of the epoxy groups used is 1 to 4, the ratio being represented by the following formula; Ratio of numbers of epoxy groups = {[molar number of (b) used] × [number of epoxy groups in 1 mole of (b)]} ÷ {[molar number of (a) used] × [number of epoxy groups in 1 mole of (a)] }. A second aspect of the present invention is an invention relating to a thermosetting resin composition being at a viscosity of 0.5 Pa·s (5 poise) or more at 25 °C, preferably 1 Pa·s (10 poise) or more at 25 °C and a viscosity of 0.5 Pa·s (5 poise) or less at 60°C and comprising (a) an epoxy resin with a naphthalene backbone , represented by the Chemical formula 3, 4 or 5; or an epoxy resin with an anthracene backbone, such as diglycidyl ether of anthracene diol and triglycidyl ether of anthracene triol (c) an acid anhydride curing agent; and (d) a metal acetonate curing catalyst represented by the Chemical formula 2 at 0.1 to 5 parts by weight per 100 parts by weight of the epoxy resins, wherein the ratio of the numbers of the epoxy groups used is 1 to 4, the ratio being represented by the following formula; Ratio of numbers of epoxy groups = {[molar number of (b) used] × [number of epoxy groups in 1 mole of (b)]} ÷ {[molar number of (a) used] × [number of epoxy groups in 1 mole of (a)] }. A third aspect of the present invention is an invention relating to an electrically insulated coil produced by winding an insulating tape base material around a stack of insulated conductor formed into a defined coil shape and thereafter impregnating and curing the electrically insulated coil with a thermosetting resin composition, wherein as the thermosetting resin composition, use is made of a thermosetting resin composition being at a viscosity of 0.5 Pa·s (5 poise) or more at 25 °C, preferably 1 Pa·s (10 poise) or more at 25 °C and a viscosity of 0.5 Pa·s (5 poise) or less at 60 °C and comprising (a) a polyfunctional epoxy resin containing three or more p-(2,3-epoxypropoxy)phenyl groups and a group represented by the Chemical formula 1; or an epoxy resin with a naphthalene backbone , represented by the Chemical formula 3, 4 or 5 or an epoxy resin with an anthracene backbone, such as diglycidyl ether of anthracene diol and triglycidyl ether of anthracene triol; (b) a bifunctional epoxy resin containing two p-(2,3-epoxypropoxy)phenyl groups; (c) an acid anhydride curing agent; and (d) a metal acetonate curing catalyst represented by the Chemical formula 2 at 0.1 to 5 parts by weight per 100 parts by weight of the epoxy resins, wherein the ratio of the numbers of the epoxy groups used is 1 to 4, the ratio being represented by the following formula; Ratio of numbers of epoxy groups = {[molar number of (b) used] × [number of epoxy groups in 1 mole of (b)]} ÷ {[molar number of (a) used] × [number of epoxy groups in 1 mole of (a)] }. A fourth aspect of the present invention is an invention relating an electrically insulated coil of stator for rotating machine , produced by incorporating into an iron core slot a electrically insulated coil produced by winding an insulating tape base material around a stack of insulated conductor formed into a defined coil shape, inserting a wedge into the external circumference groove of the iron core slot to connect the electrically insulated coil to the external end part of the iron core, and thereafter impregnating at their integrated state of the electrically insulated coil and the iron core slot with a thermosetting resin composition,and herdening wherein as the thermosetting resin composition, use is made of a thermosetting resin composition being at a viscosity of 0.5 Pa·s (5 poise) or more at 25 °C, preferably 1 Pa·s (10 poise) or more at 25 °C and a viscosity of 0.5 Pa·s (5 poise) or less at 60 °C and comprising (a) a polyfunctional epoxy resin containing three or more p-(2,3-epoxypropoxy)phenyl groups and a group represented by the Chemical formula 1; or an epoxy resin with a naphthalene backbone , represented by the Chemical formula 3, 4 or 5 or an epoxy resin with an anthracene backbone, such as diglycidyl ether of anthracene diol and triglycidyl ether of anthracene triol; (b) a bifunctional epoxy resin containing two p-(2,3-epoxypropoxy)phenyl groups; (c) an acid anhydride curing agent; and (d) a metal acetonate curing catalyst represented by the Chemical formula 2 at 0.1 to 5 parts by weight per 100 parts by weight of the epoxy resins, wherein the ratio of the numbers of the epoxy groups used is 1 to 4, the ratio being represented by the following formula; Ratio of numbers of epoxy groups = {[molar number of (b) used] × [number of epoxy groups in 1 mole of (b)]} ÷ {[molar number of (a) used] × [number of epoxy groups in 1 mole of (a)] }. A fifth aspect of the present invention is an invention relating to an electrically insulated coil of stator for rotating machine, produced by incorporating into an iron core slot an electrically insulated coil produced by winding an insulating tape base material around a stack of insulated conductor formed into a defined coil shape, inserting a wedge into the external circumference groove of the iron core slot to connect the electrical insulating coil to the external end part of the iron core, and thereafter impregnating and curing the electrically insulated coil and the iron core slot at their integrated state with a thermosetting resin composition, wherein as the insulating tape base material, use is made of an insulating tape base material with a heat conductivity as high as 0.3 to 0.8 W/mK and wherein as the thermosetting resin composition, use is made of a thermosetting resin composition being at a viscosity of 0.5 Pa·s (5 poise) or more, preferably 1.0 Pa·s (10 poise) or more at 25 °C and a viscosity of 0.5 Pa·s (5 poise) or less at 60 °C and comprising (a) a polyfunctional epoxy resin containing three or more p-(2,3-epoxypropoxy)phenyl groups and a group represented by the Chemical formula 1; or an epoxy resin with a naphthalene backbone represented by the Chemical formula 3, 4 or 5 or an epoxy resin with an anthracene backbone, such as diglycidyl ether of anthracene diol and triglycidyl ether of anthracene triol; (b) a bifunctional epoxy resin containing two p-(2,3-epoxypropoxy)phenyl groups; (c) an acid anhydride curing agent; and (d) a metal acetonate curing catalyst represented by the Chemical formula 2 at 0.1 to 5 parts by weight per 100 parts by weight of the epoxy resins, wherein the ratio of the numbers of the epoxy groups used is 1 to 4, the ratio being represented by the following formula; Ratio of numbers of epoxy groups = {[molar number of (b) used] × [number of epoxy groups in 1 mole of (b)]} ÷ {[molar number of (a) used] × [number of epoxy groups in 1 mole of (a)] }. A sixth aspect of the present invention is an invention relating to an electrically insulated coil for stator of rotating machine , produced by incorporating into an iron core slot an electrically insulated coil produced by winding an insulating tape base material around a back of insulated conductor forweel into a defined coil shape together with a semiconductive slot liner, inserting a wedge into the external circumference groove of the iron core slot to connect the electrical insulating coil to the external end part of the iron core, and thereafter impregnating and curing the electrical insulating coil and the iron core slot at their integrated state with a thermosetting resin composition, wherein as the semiconductive slot liner, use is made of a highly heat-conductive, semiconductive slot liner with a heat conductivity as high as 0.3 to 1.0 W/mK and surface resistance of 0.2 to 100 k Ω; and wherein as the thermosetting resin composition, use is made of a thermosetting resin composition being at a viscosity of 0.5 Pa·s (5 poise) or more preferably 1.0 Pa·s (10 poise) or more at 25 °C and a viscosity of 0.5 Pa·s (5 poise) or less at 60 °C and comprising (a) a polyfunctional epoxy resin containing three or more p-(2,3-epoxypropoxy)phenyl groups and a group represented by the Chemical formula 1; or an epoxy resin with a naphthalene backbone , represented by the Chemical formula 3, 4 or 5 or an epoxy resin with an anthracene backbone, such as diglycidyl ether of anthracene diol and triglycidyl ether of anthracene triol; (b) a bifunctional epoxy resin containing two p-(2,3-epoxypropoxy)phenyl groups; (c) an acid anhydride curing agent; and (d) a metal acetonate curing catalyst represented by the Chemical formula 2 at 0.1 to 5 parts by weight per 100 parts by weight of the epoxy resins, wherein the ratio of the numbers of the epoxy groups used is 1 to 4, the ratio being represented by the following formula; Ratio of numbers of epoxy groups = {[molar number of (b) used] × [number of epoxy groups in 1 mole of (b)]} ÷ {[molar number of (a) used] × [number of epoxy groups in 1 mole of (a)] }. A seventh aspect of the present invention is an invention relating to a rotating machine comprising a stator and a rotor, produced by incorporating into an iron core slot an electrical insulating coil produced by winding an insulating tape base material around a stack of insulated conductor forwed into a defined coil shape, inserting a wedge into the external circumference groove of the iron core slot to connect the electrical insulating coil to the external end part of the iron core, and thereafter impregnating and curing the electrical insulating coil and the iron core slot at their integrated state with a thermosetting resin composition, wherein as the thermosetting resin composition, use is made of a thermosetting resin composition being at a viscosity of 0.5 Pa·s (5 poise) or more, preferably 1.0 Pa·s (10 poise) or more at 25 °C and a viscosity of 0.5 Pa·s (5 poise) or less at 60 °C and comprising (a) a polyfunctional epoxy resin containing three or more p-(2,3-epoxypropoxy)phenyl groups and a group represented by the Chemical formula 1; or an epoxy resin with a naphthalene backbone , represented by the Chemical formula 3, 4 or 5 or an epoxy resin with an anthracene backbone, such as diglycidyl ether of anthracene diol and triglycidyl ether of anthracene triol; (b) a bifunctional epoxy resin containing two p-(2,3-epoxypropoxy)phenyl groups; (c) an acid anhydride curing agent; and (d) a metal acetonate curing catalyst represented by the Chemical formula 2 at 0.1 to 5 parts by weight per 100 parts by weight of the epoxy resins, wherein the ratio of the numbers of the epoxy groups used is 1 to 4, the ratio being represented by the following formula; Ratio of numbers of epoxy groups = {[molar number of (b) used] × [number of epoxy groups in 1 mole of (b)]} ÷ {[molar number of (a) used] × [number of epoxy groups in 1 mole of (a)] }. Any polyfunctional compound containing three or more p-(2,3-epoxypropoxy)phenyl groups and a group represented by the Chemical formula 1; may be used, with no specific limitation, as the polyfunctional epoxy resin containing three or more p-(2,3-epoxypropoxy)phenyl groups and a group represented by the Chemical formula 1; in accordance with the present invention. Such compound includes for example polyfunctional epoxy resins such as tris[p-(2,3-epoxypropoxy)phenyl]methane, 1,1,2-tris[p-(2,3-epoxypropoxy)phenyl]ethane, 1,1,2-tris[p-(2,3-epoxypropoxy)phenyl]propane, 1,1,3-tris[p-(2,3-epoxypropoxy)phenyl]propane, 1,1,3-tris[p-(2,3-epoxypropoxy)phenyl]butane, 1,1,2,2-tetrakis[p-(2,3-epoxypropoxy)phenyl]ethane, 1,1,3,3-tetrakis[p-(2,3-epoxypropoxy)phenyl]propane and the like. From the respect of heat resistance and viscosity, preference is given to tris[p-(2,3-epoxypropoxy)phenyl]methane, 1,1,3-tris[p-(2,3-epoxypropoxy)phenyl]butane, 1,1,2,2-tetrakis[p-(2,3-epoxypropoxy)phenyl]ethane, 1,1,3,3-tetrakis[p-(2,3-epoxypropoxy)phenyl]propane, 1,1,3-tris[p-(2,3-epoxypropoxy)phenyl]propane, among them. [Chemical formula 3] (wherein "n" and "m" are 1, 2 or 3.) [Chemical formula 4] (wherein "m" is 0,1 or 2; "n", "n' " and " n" " are 1, 2, 3 or 4; and the groups with "n", " n' " and " n" " may satisfactorily be attached independently to either one ring or both two rings of each of the naphthalene rings.) [Chemical formula 5] (wherein R is an alkyl group with 1 to 10 carbon atoms; "m" is 0,1 or 2; "n" is 1, 2 or 3; " 1 " and " 1' " are 1, 2, 3 or 4; and the groups with "n", " 1 " and " 1' " may satisfactorily be attached independently to either one ring or both two rings of each of the naphthalene rings.) The epoxy resin with the naphthalene backbone being represented by the Chemical formulas 3, 4 or 5 and the epoxy resin with the anthracene backbone, such as diglycidyl ether of anthracene diol and triglycidyl ether of anthracene triol, and to be used in accordance with the present invention, are described more specifically below. The epoxy resin with the naphthalene backbone, represented by the Chemical formula 3, includes diglycidyl ether of dihydroxynaphthalenes such as 1,6-dihydroxynaphthalene, 1, 2-dihydroxynaphthalene, 1,3-dihydroxynaphthalene, 1,4-dihydroxynaphthalene, 1,5-dihydroxynaphthalene, 1,7-dihydroxynaphthalene, 1, 8-dihydroxynaphthalene, 2,3-dihydroxynaphthalene, 2,6-dihydroxynaphthalene, and 2, 7-dihydroxynaphthalene; triglycidyl ether of trihydroxynaphthalenes such as 1,2,3-trihydroxynaphthalene, 1,2,4-trihydroxynaphthalene, 1,2,5-trihydroxynaphthalene, 1,2,6-trihydroxynaphthalene, 1,2,7-trihydroxynaphthalene, 1,2,8-trihydroxynaphthalene, 1,3,5-trihydroxynaphthalene, 1,3,6-trihydroxynaphthalene, 1,3,7-trihydroxynaphthalene, 1,3,8-trihydroxynaphthalene, 1,4,5-trihydroxynaphthalene, 1,4,6-trihydroxynaphthalene, 1,4,7-trihydroxynaphthalene, 1,6,7-trihydroxynaphthalene, and 2,3,6-trihydroxynaphthalene; tetradiglycidyl ether of tetrahydroxynaphthalenes such as 1,3,6,7-tetrahydroxynaphthalene and 1,2,6,7-tetrahydroxynaphthalene. The epoxy resin with the naphthalene backbone, represented by the Chemical formula 4, includes dihydroxynaphthalene, trihydroxynaphthalene and tetrahydroxynaphthalene singly or polyglycidyl ether of a novolak type resin of a mixture thereof with formaldehyde. Additionally, the dihydroxynaphthalene, trihydoxynaphthalene and tetrahydroxynaphthalene alone or polyglycidyl ether of a novolak-type epoxy resin of a mixture thereof with acetoaldehyde or the like, is also useful. As the epoxy resin with the naphthalene backbone, represented by the Chemical formula 5, polyglycidyl ether of a novolak type resin comprising a mixture of the dihydroxynaphthalene, trihydroxynaphthalene and tetrahydroxynaphthalene with phenol, aminophenol, cresol and the like and formaldehyde, is useful. Still further, polyglycidyl ether of a novolak type resin comprising a mixture of the dihydroxynaphthalene, trihydroxynaphthalene, and tetrahydroxynaphthalene with phenol, aminophenol, cresol and the like and acetoaldehyde and the like, is also useful. A mixture of those represented by the Chemical formulas 3, 4 and 5 is also effective. Among them, preference is given to the epoxy resins represented by the Chemical formula 4 and 5 and a mixture of the resins with 1,6-dihydroxynaphthalene diglycidyl ether, from the respect of heat resistance and viscosity. If necessary, additionally, addition of amines and phenols or modification thereof may satisfactorily be carried out. Bifunctional epoxy resins containing two p-(2,3-epoxypropoxy)phenyl groups, such as diglycidyl ether of bisphenol A, diglycidyl ether of bisphenol F and diglycidyl ether of bisphenol AD, are useful from the respect of heat resistance and viscosity. The metal acetonate curing catalysts represented by the Chemical formula 2 to be used in accordance with the present invention include curing catalysts selected from the group consisting of manganese (III) acetylacetonate, manganese (III) benzoylacetonate, cobalt (II) acetylacetonate, cobalt (III) acetylacetonate, cobalt (II) benzoylacetonate, zinc (II) acetylacetonate, chromium (III) acetylacetonate, titanyl acetylacetonate, aluminium (III) acetylacetonate, nickel (II) acetylacetonate, vanadium (III) acetylacetonate, zirconium (IV) acetylacetonate, sodium (I) acetylacetonate, potassium (I) acetylacetonate and a mixture thereof. The metal acetonate curing catalysts may be blended at any ratio, with no specific limitation, but preferably at 0.1 to 5 parts by weight per 100 parts by weight of the epoxy resins. If the amount is much, however, the pot life tends to be shorter, while the resin may tend to flow if the amount is too less. Any general acid anhydride may be used, with no specific limitation, in accordance with the present invention. Such compound includes for example methylhexahydrophthalic anhydride, hexahydrophthalic anhydride, methyltetrahydrophthalic anhydride, tetrahydrophthalic anhydride, nadic anhydride, methylnadic anhydride, dodecylsuccinic anhydride, succinic anhydride, octadecylsuccinic anhydride, maleic anhydride, benzophenone tetracarboxylic anhydride singly, or a mixture thereof. Among them, preferably, the compound includes nadic anhydride and methylnadic anhydride from the respect of heat resistance. From the respect of heat resistance, the ratio of blending an acid anhydride to the epoxy resin is preferably at 0.8 to 1.2 in equivalent ratio. The ratio of a polyfunctional epoxy resin with three or more functional groups blended with a bifunctional epoxy resin is not with specific limitation, but preferably, 0.1 to 19 parts by weight of a bifunctional epoxy resin is blended with one part by weight of a polyfunctional epoxy resin. If the polyfunctional epoxy resin is much, the viscosity prior to curing tends to increase, involving such tendency that the resulting composition may turn hard and fragile; adversely when the bifunctional epoxy-resin is much, the viscosity decreases while the heat resistance tends to be reduced. From the respect of the compatibility between viscosity and heat resistance, effectively, 1 to 9 parts by weight of a bifunctional epoxy resin should be blended with one part by weight of a polyfunctional epoxy resin, in particular. The ratio of blending (a) a polyfunctional epoxy resin containing three or more p-(2,3-epoxypropoxy)phenyl groups and a group represented by the Chemical formula 1;, or an epoxy resin with a naphthalene backbone or an epoxy resin with an anthracene backbone, such as diglycidyl ether of anthracene diol and triglycidyl ether of anthracene triol, represented by the Chemical formula 3, 4 or 5 to (b) a bifunctional epoxy resin containing two p-(2,3-epoxypropoxy)phenyl groups, is represented by the following formula; Ratio of numbers of epoxy groups = {[molar number of (b) used] × [number of epoxy groups in 1 mole of (b)]} ÷ {[molar number of (a) used] × [number of epoxy groups in 1 mole of (a)] }. From the respect of heat resistance, viscosity and pot life, preferably, the ratio of the numbers of the epoxy groups to be used is 1 to 4. So as to produce an electrically insulated coil with high heat resistance with less flow of a thermosetting resin composition, the viscosity of the thermosetting resin composition is 0.5 Pa·s (5 poise) or more ,preferably 1.0 Pa·s (10 poise) or more at 25 °C and 0.5 Pa·s (5 poise) or less at 60 °C. The insulating base material to be used in accordance with the present invention includes mica sheet, polyimide sheet, polyamide sheet, polyparabenic acid sheet, polyimide ether sheet, polyether ether ketone sheet, polysulfide sheet and the like. Mica includes for example non-calcined soft composite mica, non-calcined hard composite mica, calcined hard composite mica, calcined soft composite mica, synthetic mica or aramide-mixed mica. Furthermore, highly heat-conductive mica with inorganic fillers such as silica, alumina, and boron nitride, dispersed therein, is also illustrated, as described in Japanese Patent Publication No. Sho 56-38006.Inorganic fillers can be also added to binder. Mica of itself has good insulating performance, but with lower strength, and therefore, mica can be wound around a conductor with much difficulty. To impart mice with strength, therefore, mica should be attached to a reinforcing material by means of a binder. The reinforcing material for mica includes for example glass fiber, aramide, aramide-mixed paper, films of polyamide imide, polyester, polyimide ether, polyether ether ketone, polyether sulfone, polyparabenic acid, polysulfide or polyimide; and films with a higher heat conductivity, produced by filling silica or alumina into the aforementioned films. Among them, glass fiber and polyimide film are preferable as the reinforcing material for mica from the respect of heat resistance. Particularly, silica-or alumina-filled glass fiber and polyimide film with an increased thermal conductivity, are preferable. As such binder, any binder may be satisfactory as long as the binder can bond mica to the reinforcing material. The binder includes epoxy resin, silicone resin, alkyd resin, polyester resin, epoxy ester resin and the like. From the respect of heat resistance, among them, a binder reactive with thermosetting resin of the present invention is particularly preferable. If the insulating base material is hard, additionally, the insulating base material may satisfactorily be softened for use. The binder should be contained at any content in the insulating base material with no specific limitation, but preferably at 3 to 40 % by weight, particularly at 5 to 20 % by weight. If the binder content is high, the amount of the thermosetting resin composition in impregnation is so less that the heat resistance tends to decrease. If the binder content is less, alternatively, the adhesive strength is so deteriorated that the insulating base material is peeled off, which causes that the base material is likely to be wound back on a conductor with much difficulty. So as to elevate the adhesive strength of the insulating base material, treatment of the material mica or the reinforcing agent with a surfactant may be effected satisfactorily or a surfactant may be added to the binder to procure better performance. Such surfactant includes for example silane surfactants such as γ-chloropropyltrimethoxysilane. vinyltrichlorosilane, vinyltriethoxysilane, vinyltrimethoxysilane, vinyl tris (β-methoxyethoxy)silane, γ - methacryloxypropyltrimethoxysilane, β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-mercaptopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, N-β-(aminoethyl)-γ-aminopropyltrimethoxysilane, and γ-ureidopropyltriethoxysilane; titanate surfactants such as isopropylisostearoyltitanate, isopropyltrioctanoyltitanate, isopropylmethacryloylisostearoyltitanate, isopropyltridodecyltitanate, isopropylisostearoyldiacryltitanate, isopropyl tris(dioctylphosphate)titanate, isopropyltricumylphenyltitanate, isopropyl tris(dioctylpyrophosphate)titanate, isopropyl tris(n-aminoethyl-aminoethyl)titanate, tetraisopropyl bis (dioctylphosphite)titanate, tetraoctyl bis(didodecylphosphite)titanate, tetra(2,2-diallyloxymethyl-1-butyl) bis (ditridecyl)phosphitetitanate, di-isostearoylethylene titanate, and bis(dioctylpyrophosphate)ethylene titanate; aluminium surfactants such as ethyl acetoacetate aluminium diisopropylate and aluminium tris(ethyl acetoacetate); or zirconium surfactants or the like. Among them, preference is given to γ-glycidoxypropyltrimethoxysilane, β-(3,4-epoxycylohexyl)ethyltrimethoxysilane, γ-mercaptopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, N-β-(aminoethyl)- γ-aminopropyltrimethoxysilane, isopropylisostearoyltitanate, isopropyltrioctanoyltitanate, ethyl acetoacetate aluminium diisopropylate and aluminium tris(ethyl acetoacetate). Two or more of the surfactants may satisfactorily be mixed together. If necessary, furthermore, monoepoxy resins such as cyclohexene vinyl monooxide, octylene oxide, butyl glycidyl ether, styrene oxide, phenylglycidyl ether, glycidyl methacrylate, and allyl glycidyl ether may be added as a diluent. However, generally, diluents have an effect of lowering viscosity, which is accompanied by the decrease of heat resistance. Therefore, the amount of the diluents should be suppressed at a lower level. As such filler, hydrated alumina, hydrated magnesium, calcium carbonate, zirconium silicate, calcium silicate, talc, clay, mica, glass fiber powder and the like may be added as the filler, other than silica powder, quartz glass powder and alumina powder. The present invention will now be described in more detail in examples, but the invention is not limited to these examples. The abbreviations of the epoxy resins, curing agents and curing catalysts used in the examples are as shown below. 1,2-DGON; 1,2-diglycidyloxynaphthalene; epoxy equivalent of 141 1,3-DGON; 1,3-diglycidyloxynaphthalene; epoxy equivalent of 141 1,4-DGON; 1,4-diglycidyloxynaphthalene; epoxy equivalent of 141 1,5-DGON; 1,5-diglycidyloxynaphthalene; epoxy equivalent of 141 1,6-DGON; 1,6-diglycidyloxynaphthalene; epoxy equivalent of 141 1,7-DGON; 1,7-diglycidyloxynaphthalene; epoxy equivalent of 141 1,8-DGON; 1,8-diglycidyloxynaphthalene; epoxy equivalent of 141 2,3-DGON; 2,3-diglycidyloxynaphthalene; epoxy equivalent of 141 2,6-DGON; 2,6-diglycidyloxynaphthalene; epoxy equivalent of 141 2,7-DGON; 2,7-diglycidyloxynaphthalene; epoxy equivalent of 141 PDGON; polymerized 1,6-diglycidyloxynaphthalene; epoxy equivalent of 250 and softening point of 67 °C GONDGONM; 1-(2-glycidyloxy-1-naphthyl)-1-(2',7'-diglycidyloxy-1-naphthyl)methane; epoxy equivalent of 187 and softening point of 75 °C BDGON; 1,1-bis(2,7-diglycidyloxy-1-naphthyl)methane; epoxy equivalent of 161 and softening point of 91 °C BDGOE; 1,1-bis(2,7-diglycidyloxy-1-naphthyl)ethane; epoxy equivalent of 165 and softening point of 91 °C PGENCN; polyglicidyl ether of novolak of a mixture of cresol and 2-hydroxynaphthalene; epoxy equivalent of 225 and softening point of 84 °C TKEPPE; 1,1,2,2-tetrakis[p-(2,3-epoxypropoxy)phenyl]ethane; epoxy equivalent of 192 TEPPM; 1,1,3-tris[p-(2,3-epoxypropoxy)phenyl]propane; epoxy equivalent of 161 TEPPB; 1,1,3-tris[p-(2,3-epoxypropoxy)phenyl]butane; epoxy equivalent of 196 BPAN; Novolak-type epoxy of bisphenol A; epoxy equivalent of 198 DGEBA; diglycidyl ether of bisphenol A; epoxy equivalent of 175 ECHMECC; 3,4-epoxycylohexylmethyl-(3,4-epoxy)cyclohexane carboxylate; epoxy equivalent of 138 DGEBF; diglycidyl ether of bisphenol F; epoxy equivalent of 170 POGEPN; polyglycidyl ether of phenol Novolak; epoxy equivalent of 170 MHAC-P; methylnadic anhydride; acid anhydride equivalent of 178 HN-5500; methylhexahydrophthalic anhydride; acid anhydride equivalent of 168 HN-2200; methyltetrahydrophthalic anhydride; acid anhydride equivalent of 166 Mn(III)AA; manganese (III) acetylacetonate Mn(III) BA; manganese (III) benzoyl acetonate Co(II) AA; cobalt (II) acetylacetonate Co(III) AA; cobalt (III) acetylacetonate Co (II) BA; cobalt (II) benzoylacetonate TiAA; titanyl acetylacetonate ZrAA; zirconium (IV) acetylacetonate VAA; vanadium (III) acetylacetonate Examples 1 to 56 and Comparative Examples 1 to 8 1. Preparation of thermosetting resin compositions and assessment of the performance Table 1 Examples Epoxy resins Curing agents Curing catalysts Viscosity (x 0.1 Pa·s) at 25 °C Viscosity (x 0.1 Pa·s) at 60 °C Pot life Heat-resistant temperature Table 2 Table 3 Table 4 Table 5 Table 6 Table 7 Table 8 In Tables 1 to 8, the ratio (a)/(b) is the ratio of number of epoxy groups. Epoxy resins, curing agents and curing catalysts were mixed together at the mixing ratios shown in Tables 1 to 8, prior to sufficient dissolution under agitation and heating. Then, the viscosity increased, until the viscosity exceeded 0.5 Pa·s (5 P) at 60 °C. Therefore, the amounts of curing catalysts as described in the Tables were added to parts of the curing agents, prior to heating to 100 to 120 °C for agitation and dissolution, and the resulting mixtures were left to stand at room temperature. During dissolution under heating, parts of the curing agents were vaporized with stimulating odor. Then, the remaining curing agents and epoxy resins were added to the mixtures for sufficient agitation. In any of the Examples, the viscosity was 0.5 Pa·s (5 P) or less at 60 °C. Mixing the curing catalysts at amounts shown in the Tables with parts of the epoxy resins and heating the catalysts to 100 to 120 °C under agitation for dissolution, alternatively, the resulting mixtures were left at ambient temperature. Then, the remaining epoxy resins and the remaining curing agents were added to the mixtures for sufficient agitation. In any of the Examples, the viscosity was 0.5 Pa·s (5 P) or less at 60 °C. As the method for mixing the curing catalysts, preference is given to a method comprising dissolving the catalysts in the curing agents or the epoxy resins under heating and subsequently adding the remaining parts as shown in the Tables to the resulting mixtures. For environmental hygiene and for mixing the calculated amounts to be mixed, most preferably, the curing catalysts are dissolved in the epoxy resins under heating. The viscosity at 25 °C and 60 °C, pot life and heat-resistant temperature coefficient of a thermosetting resin composition are shown in the Tables, when a curing catalyst was dissolved in the epoxy resins. Herein, the viscosity was measured by a B-type viscometer; the pot life was defined as a period in day until the initial viscosity of thermosetting resin composition increased by 2 fold. The heat-resistant temperature was determined according to IEC Pub.216. More specifically, cured matters each of a size of 2 x 50 x 50 mm were left to stand in air-circulation type thermostats individually maintained at 270 °C, 250 °C and 230 °C, and thereafter, the samples were drawn out at a predetermined interval, to measure the weight to calculate the decrement due to heating. The time required for the decrement due to heating to reach 10 % by weight was determined, which was defined as life. Plotting then the life vs. the inverse number of absolute temperature, a linear relation was established in any case. Extrapolating the line, the temperature for the life to reach 20,000 hours was determined and defined as the heat-resistant: temperature. The heat resistance of the thermosetting resin compositions for impregnating electric appliances is determined on the basis of the heat-resistant temperature. Tables 1 to 3 indicate that the thermosetting resin compositions comprising (a) an epoxy resin with a naphthalene backbone , represented by the Chemical formula 3, 4 or 5 or an epoxy resin with an anthracene backbone, such as diglycidyl ether of anthracene diol and triglycidyl ether of anthracene triol; (b) a bifunctional epoxy resin containing two p-(2,3-epoxypropoxy)phenyl groups; (c) an acid anhydride curing agent; and (d) a metal acetonate curing catalyst represented by the Chemical formula 2 at 0.1 to 5 parts by weight per 100 parts by weight of the epoxy resins, wherein the ratio of the numbers of the epoxy groups used is 1 to 4, the ratio being represented by the following formula; Ratio of numbers of epoxy groups = {[molar number of (b) used] × [number of epoxy groups in 1 mole of (b)]} ÷ {[molar number of (a) used] × [number of epoxy groups in 1 mole of (a)] }, are at a viscosity of 0.5 Pa·s (5 poise) or more at 25 °C and a viscosity of 0.5 Pa·s (5 poise) or less at 60 °C and have a heat-resistant temperature of 200 °C or more. Table 3 indicates that when the ratio (b)/(a) as the ratio of the numbers of the epoxy groups used is 1 to 4 as represented by the following formula, provided that (b) is a bifunctional epoxy resin containing two p-(2,3-epoxypropoxy)phenyl groups and (a) is an epoxy resin with a naphthalene backbone or an epoxy resin with an anthracene backbone, such as diglycidyl ether of anthracene diol and triglycidyl ether of anthracene triol, represented by the Chemical formula 3, 4 or 5; Ratio of numbers of epoxy groups = {[molar number of (b) used] × [number of epoxy groups in 1 mole of (b)]} ÷ {[molar number of (a) used] × [number of epoxy groups in 1 mole of (a)] }, the heat-resistant temperature is above 200 °C and the viscosity then is 0.5 Pa·s (5 poise) or more at 25 °C and 0.5 Pa·s (5 poise) or less at 60 °C; and when the ratio is 2 to 3, the heat-resistant temperature is larger, preferably. If the (b)/(a) ratio is 0.7, the heat-resistant temperature is small while the viscosity is too small, which causes the tendency such that the resin flows out during impregnation and curing of coil. If the (b)/(a) ratio is 5.0, alternatively, the viscosity then is too high, which causes the tendency such that the impregnation with the resin hardly occurs. It can be said that the ratio outside the range of 1 to 4 is not preferable. Tables 4 to 7 indicate that manganese (III) acetylacetonate, manganese (III) benzoylacetonate, cobalt (II) acetylacetonate, cobalt (III) acetylacetonate, cobalt (II) benzoylacetonate, titanyl acetylacetonate, vanadium (III) acetylacetnaate, zirconium (IV) acetylacetnaate and the like are preferable as the curing catalyst. Table 5 indicates that when a thermosetting resin composition comprises (b) a bifunctional epoxy resin containing two p-(2,3-epoxypropoxy)phenyl groups and (a) a polyfunctional epoxy resin containing three or more p-(2,3-epoxypropoxy)phenyl groups and a group represented by the Chemical formula 1, provided that the (b)/(a) ratio as the ratio of the numbers of the epoxy groups used is 1 to 4, the ratio being represented by the following formula; Ratio of numbers of epoxy groups = {[molar number of (b) used] × [number of epoxy groups in 1 mole of (b)]} ÷ {[molar number of (a) used] × [number of epoxy groups in 1 mole of (a)] }, the thermosetting resin composition has a heat-resistant temperature of 200 °C or more and is at a viscosity of 0.5 Pa·s (5 poise) or more at 25 °C and 0.5 Pa·s (5 poise) or less at 60 °C and that the heat-resistant temperature thereof is high within a range of 2 to 3 as the (b)/(a) ratio. If the (b)/(a) ratio is 0.6, the heat-resistant temperature is small while the viscosity is too small, which causes the tendency such that the resin flows out during impregnation and curing of coil. If the (b)/(a) ratio is 5.0, alternatively, the viscosity then is too high, which causes the tendency such that the impregnation with the resin is hardly effected. It can be said that the ratio outside the range of 1 to 4 is not preferable. Table 6 indicates that the metal acetonate curing catalyst represented by the Chemical formula 2 to be used in accordance with the present invention is contained at 0.1 to 5 parts by weight per 100 parts by weight of the epoxy resin. If the amount is too much, the pot life tends to be shortened; if the amount is too less, the curing performance is deteriorated, involving the tendency of resin flow. Table 8 indicates that preference is given as the curing agent to methylhexahydrophthalic anhydride, methyltetrahydrophthalic anhydride, tetrahydrophthalic anhydride, and methylnadic anhydride; and that the acid anhydride should preferably be mixed with the epoxy resin at a ratio as an equivalent ratio of 0.8 to 1.2, from the respect of heat resistance. 2. Preparation of insulating tape base material 1 A binder solution was prepared by adjusting the concentration of TEPPM by means of methyl ethyl ketone so that the non-volatile part of the solution might be at 50 %. By using the binder solution then, a calcined soft composite mica filled with an aromatic polyamide fibrid was attached to glass cloth, while the solvent was vaporized simultaneously. The binder contents in the resulting glass-reinforced mica tape (insulating tape base material) corresponded to the non-volatile parts, and therefore, three types of the insulating base material were thus prepared at the binder contents of about 5, 20 and 30 % by weight (based on the total weight of the insulating tape base material). Cutting these types of the insulating tape base material, tapes of a 25-mm width were produced. 3. Preparation of insulating tape base material 2 A binder solution was prepared by adjusting the concentrations of POEPN and alumina by means of methyl ethyl ketone so that the non-volatile parts thereof might be at 50 %. By using the binder solution then, a calcined soft composite mica filled with an aromatic polyamide fibrid was attached to glass cloth, while the solvent was vaporized simultaneously. The binder contents in the resulting glass-reinforced mica tape (insulating tape base material) corresponded to the non-volatile parts, and therefore, three types of the insulating base material were thus prepared at the binder contents of about 5, 20 and 30 % by weight (based on the total weight of the insulating tape base material). Cutting these types of the insulating tape base material, tapes of a 25-mm width and with heat conductivity of 0.3 to 0.8 W/mK were produced. 4. Preparation of insulating tape base material 3 A binder solution was prepared by adjusting the concentrations of POGEPN and alumina by means of methyl ethyl ketone. By using the binder solution then, a calcined soft composite mica filled with an aromatic polyamide fibrid and alumina was attached to glass cloth, while the solvent was vaporized simultaneously. The binder contents in the resulting glass-reinforced mica tape (insulating tape base material) corresponded to the non-volatile parts, and therefore, three types of the insulating base material were thus prepared at the binder contents of about 5, 20 and 30 % by weight (based on the total weight of the insulating tape base material). Cutting these types of the insulating tape base material, tapes of a 25-mm width and with heat conductivity of 0.3 to 0.8 W/mK were produced. 5. Preparation of insulating tape base material 4 A binder solution was prepared by adjusting the concentrations of TEPPM and alumina by means of methyl ethyl ketone so that the non-volatile part of the solution might be at 50 %. By using the binder solution then, a calcined soft composite mica filled with an aromatic polyamide fibrid was attached to glass cloth, while the solvent was vaporized simultaneously. The binder contents in the resulting glass-reinforced mica tape (insulating tape base material) corresponded to the non-volatile parts, and therefore, three types of the insulating base material were thus prepared at the binder contents of about 5, 20 and 30 % by weight (based on the total weight of the insulating tape base material). Cutting these types of the insulating tape base material, tapes of a 25-mm width and with heat conductivity of 0.3 to 0.8 W/mK were produced. 6. Preparation of insulating tape base material 5 A binder solution was prepared by adjusting the concentrations of TEPPM and alumina by means of methyl ethyl ketone so that the non-volatile part of the solution might be at 50 %. By using the binder solution then, a calcined soft composite mica filled with an aromatic polyamide fibrid and alumina was attached to polyimide film, while the solvent was vaporized simultaneously. The binder contents in the resulting glass-reinforced mica tape (insulating tape base material) corresponded to the non-volatile parts, and therefore, three types of the insulating base material were thus prepared at the binder contents of about 5, 20 and 30 % by weight (based on the total weight of the insulating tape base material). Cutting these types of the insulating tape base material, tapes of a 25-mm width and with heat conductivity of 0.3 to 0.8 W/mK were produced. 7. Production of electrically insulated coils Winding the insulating tape base materials described above in the items 2 to 6 around stacks of insulated conductors, followed by in vacuo impregnation with thermosettinq resin compositions as described above in the item 1 under pressure and subsequent heating at 100 °C for 10 hours, 150 °C for 3 hours and 230 °C for 10 hours, the compositions were cured. No peeling was observed on the insulating layers of the electrically insulated coils thus produced. Then, the water resistance and heat resistance were tested by the following methods. Fig.1 is a perspective, partially cutout view of an electrically insulated coil measured. Insulating layer 2 wound around and arranged on stack of insulated conductor 1 is impregnated and cured with a thermosetting resin composition, and thus, these are integrated together. a. heat resistance test One cycle of heating and moisture absorption test at 270 °C for 24 hours and 40 °C for 24 hours in 95 % RH was carried out 10 cycles. At each cycle, Dissipation factor "tan δ" and insulation resistance were measured. In any of the Examples, the tan δ was 10 % or less after the 10 cycles. Additionally, the insulation resistance was 10 12 Ω or more. In any of Comparative Examples, alternatively, the tan δ after the 10 cycles was 20 % or more. Additionally, the insulation resistance was 10 10 Ω or less. b. Water resistance test Along the tape winding direction on the insulating layer of an electrical insulating coil, a test piece of the insulating layer alone was cut out in a size of 10-mm width and 60-mm length. The bending strength thereof was measured at 25 °C under a load on the central part between two supported points at an interval of 40 mm. Similarly, the bending strength after 24-hr immersion of the test piece in water at 40°C was measured to determine the being strength retention rate. In any of the examples, the rate was 80 % or more. In any of the Comparative examples, thorato was 60 % or less. c. Electric performance test The temperature characteristics of the Dissipation factor "tan δ" of the electrical insulating coil produced in Example 1 are shown as the relation in graphs between the temperature (°C; on the axis of abscissa) and the tan δ (%; on the axis of ordinate) in Fig.2. In Fig.2, "A" represents the characteristic curve at an initial insulation stage; "B" represents the characteristic curve after 1000-hr heating at 250 °C in the Example 1. Furthermore, Fig.3 is a thermal endurance graph depicting the relation between the heat-resistant life (h; on the axis of ordinate) of an electrical insulating coil of the present invention and temperature (°C; on the axis of abscissa). As shown in Fig.3, the coil of the present invention is highly heat resistant in the heat-resistant life at a motorette test according to US Standard IEEE. NO.275, and it is indicated that the coil is usable at 200 °C or more. In Examples 2 to 56, the coils of the present invention are highly heat resistant in the heat-resistant life at a motorette test according to US Standard IEEE. NO.275, and it is indicated that the coils are usable at 200 °C or more. A tape with a higher heat conductivity, if used as the insulating tape base material, can have better thermal dispersion, which enables the production of a small-scale and light-weight rotating machine at a low cost. Particularly, a heat conductivity of 0.3 to 0.8 W/mK is effective. On contrast, electrically insulated coils produced by using thermosetting resin compositions of the Comparative Examples showed poor voltage profile as dissipation factor with larger corona discharge, so that the heat-resistant life was at 190 °C or less by the motorett test. 8. Production of stators of rotating machine Incorporating each of the electrically insulated coils described in the item 7, together with a slot liner, into the slot of an iron core and inserting a wedge on the external circumference groove of the iron core, a stator of rotating machine was produced. In any of the Examples, the impregnation of the insulating layers of the electrically insulated coils with the cured matters of the thermosetting resin compositions was sufficiently effected, with no peeling observed. In any of the Comparative Examples, alternatively, cured products of the thermosetting resin compositions were almost not filled in between the electrically insulated coils and the iron core slots, with the resultant poor voltage profile as dissipation factor and with larger corona discharge. Example 57 Production of stators of rotating machine Winding each of the insulating tape base materials described in the item 2 around a stack of insulated conductor formed into a defined coil shape, coil 3 as shown in Fig.4 was prepared. As shown in Fig.5, the coil 3 was incorporated together with slot liner 4 into the slot of iron core 5, followed by insertion of wedge 6 on the external circumference groove of the iron core slot. Subsequently onnecting the electrical insulating coil at the external end part of the iron core and impregnating in vacuo the electrically insulated coils and the iron core slots together at their integrated state with a thermosetting resin composition in Tables 1 to 8, prior to heating at 175 °C for 4 hours, a stator of rotating machine was produced. In any of the Examples, the impregnation of the insulating layers of the electrically insulated coils with the cured products of the thermosetting resin compositions was sufficiently effected, with no peeling observed. The cured products of the thermosetting resin compositions were also completely filled in between the electrical insulating coils and the iron core slots. In any of the Comparative Examples, alternatively, almost cured products of the thermosetting resin compositions were not filled in between the electrically insulated coils and the iron core slots, with the resultant poor voltage profile as dielectric tangent and with larger corona discharge. Example 58 Production of stators of rotating machines. Winding each of the insulating tape base materials described in the item 3, 4, 5 or 6 around a stack of insulated conductor formed into a defined coil shape, coil 3 as shown in Fig.4 was prepared. As shown in Fig.5, the coil 3 was incorporated together with highly heat-conductive, semiconductive slot liner 4 with a heat conductivity of 0.3 to 1.0 W/mK and surface resistance of 0.2 to 100 k Ω into the slot of iron core 5, followed by insertion of wedge 6 on the external circumference groove of the iron core slot. Subsequently connecting the electrical insulating coil at the external end part of the iron core and impregnating in vacuo the electrically insulated coils and the iron core slots together at their integrated state with a thermosetting resin composition in Tables 1 to 8, prior to heating at 175 °C for 4 hours, a stator of rotating machine was produced. In any of the Examples, the impregnation of the insulating layers of the electrically insulated coils with the cured matters of the thermosetting resin compositions was sufficiently effected, with no peeling observed. The cured matters of the thermosetting resin compositions were completely filled in between the electrically insulated coils and the iron core slots. In any of the Comparative Examples, alternatively, almost cured matters of the thermosetting resin compositions were not filled in between the electrical insulating coils and the iron core slots, with the resultant poor voltage profile as dielectric tangent and with larger corona discharge. It is indicated that stators of rotating machine wound with an insulating tape base material with a heat conductivity as high as 0.3 to 0.8 W/mK has greater thermal dispersion performance than stators of rotating machine wound with an insulating tape base material with a heat conductivity of 0.2 W/mK or less; if these stators are of the same size, the stator wound with the material with a heat conductivity of 0.3 to 0.8 W/mK can pass a larger power and higher electric current; at the same power level, the equipment therefor can be made small and light in weight, resulting in cost reduction. Example 59 Production of stators of rotating machine- Winding each of the insulating tape base materials described in the items 2 to 6 around a stack of insulated conductor formed into a defined coil shape, coil 3 as shown in Fig.4 was prepared. As shown in Fig.5, the coil 3 was incorporated together with highly heat-conductive, semiconductive slot liner 4 with a heat conductivity of 0.3 to 1.0 W/mK and surface resistance of 0.2 to 100 k Ω into the slot of iron core 5, followed by insertion of wedge 6 on the external circumference groove of the iron core slot. Subsequently connecting the electrically insulated coil at the external end part of the iron core and impregnating in vacuo the electrically insulated coils and the iron core slots together at their integrated state with a thermosetting resin composition in Tables 1 to 8, prior to heating at 175 °C for 4 hours, a stator of roating machine was produced. In any of the Examples, the impregnation of the insulating layers of the electrically insulated coils with the cured matters of the thermosetting resin compositions was sufficiently effected, with no peeling observed. The cured matters of the thermosetting resin compositions were completely filled in between the electrical insulating coils and the iron core slots. In any of the Comparative Examples, alternatively, almost cured matters of the thermosetting resin compositions were not filled in between the electrical insulating coils and the iron core slots, with the resultant poor voltage profile as dielectric tangent and with larger corona discharge. It is indicated that a stator of rotating machine using a highly heat-conductive, semi electrical conductive slot liner with a heat conductivity as high as 0.3 to 0.8 W/mK and with surface resistance of 0.2 to 100 k Ω has higher thermal dispersion performance than a stator of rotating machine wound with an insulating tape base material with a heat conductivity of 0.2 W/mK or less; if these stators are of the same size, the stator using a highly heat-conductive, semi electrical conductive slot liner with a heat conductivity as high as 0.3 to 0.8 W/mK and with surface resistance of 0.2 to 100 kΩ can pass a larger power and higher electric current; at the same power level, the equipment therefor can be made small and light in weight with cost reduction. It is indicated also that a stator of rotating machine using a highly heat-conductive, semiconductive slot liner with a heat conductivity as high as 0.3 to 1.0 W/mK and surface resistance of 0.1 to 100 k Ω and using an insulating tape base material with a high heat conductivity of 0.3 to 0.8W/mK has the highest thermal dispersion performance; at the same size, the stator can pass a larger power and higher electric current; at the same power level, the equipment therefor can be made small and light in weight, with cost reduction. Production of revolving armatures Example 60 production of rotating machine As shown in Fig.7, an electric motor was prepared from a combination of stator 7 as produced in Example 57 to 59 with armature coil 8 . The stator using a highly heat- conductive, semi electric conductive slot liner with a heat conductivity of 0.3 to 1.0 W/mK and with surface resistance of 0.2 to 100 k Ω and using a highly heat-conductive insulating tape base material with a heat conductivity of 0.3 to 0.8 W/mK has improved thermal dispersion performance by 20 % or more, compared with other rotating machine , with the resultant small machine size by 25 % or more reduction and weight reduction by 23 % or more. Thus, less materials are required, whereby the cost can be reduced distinctively, and additionally, only a smaller equipment space is needed. As apparently shown in the above description, in accordance with the present invention, the following advantages are realized; a high heat-resistant electrically insulated coil with less flow of a thermosetting resin composition can be produced, when as the thermosetting resin composition for impregnating the electrical insulating coil to be used at single impregnation process or total impregnation process, use is made of a thermosetting resin composition of a viscosity of 0.5 Pa·s (5 poise) or more ,prefably to poise or more at 25 °C and a viscosity of 0.5 Pa·s (5 poise) or less at 60 °C, comprising (a) a polyfunctional epoxy resin containing three or more p-(2,3-epoxypropoxy)phenyl groups and a group represented by the Chemical formula 1; or an epoxy resin with a naphthalene backbone represented by the Chemical formula 3, 4 or 5 or an epoxy resin with an anthracene backbone, such as diglycidyl ether of anthracene diol and triglycidyl ether of anthracene triol; (b) a bifunctional epoxy resin containing two p-(2,3-epoxypropoxy)phenyl groups; (c) an acid anhydride curing agent; and (d) a metal acetonate curing catalyst represented by the Chemical formula 2 at 0.1 to 5 parts by weight per 100 parts by weight of the epoxy resins, wherein the ratio of the numbers of the epoxy groups used is 1 to 4, the ratio being represented by the following formula; Ratio of numbers of epoxy groups = {[molar number of (b) used] × [number of epoxy groups in 1 mole of (b)]} ÷ {[molar number of (a) used] × [number of epoxy groups in 1 mole of (a)] }. By selecting an total impregnation process by using a highly heat-conductive insulating tape base material with a heat conductivity of 0.3 to 0.8 W/mK and using a highly heat-conductive, semi electrical conductive slot liner with a heat conductivity of 0.3 to 1.0 W/mK and with surface resistance of 0.2 to 100 kΩ, higher thermal dispersion performance can be attained; at the same size, such revolving armature can pass a larger power and higher electric current; at the same power, such a rotating machine with a smaller machine size and light weight can be produced at low cost.

Claims: A thermosetting resin composition having a viscosity of 0.5 Pa·s (5 Poise) or more at 25 °C and a viscosity of 0.5 Pa·s (5 Poise) or less at 60 °C and comprising (a) a polyfunctional epoxy resin containing three or more p-(2,3-epoxypropoxy)phenyl groups and a group represented by chemical formula (1): (b) a bifunctional epoxy resin containing two p-(2,3-epoxypropoxy)phenyl groups; (c) an acid anhydride curing agent; and (d) a metal acetonate curing catalyst represented by chemical formula (2): (wherein X and Y represent methyl group or phenyl group; Me represents Mn, Co, Zn or Zr; and "n" represents the coordination number) at 0.1 to 5 parts by weight per 100 parts by weight of the epoxy resins, wherein the ratio of the number of the epoxy groups used is 1 to 4, the ratio being represented by the following formula: ratio of number of epoxy groups = {[molar number of (b) used] x [number of epoxy groups in 1 mole of (b)]} ÷ {[molar number of (a) used] x [number of epoxy groups in 1 mole of (a)]}. A thermosetting resin composition having a viscosity of 0.5 Pa·s (5 Poise) or more at 25 °C and a viscosity of 0.5 Pa·s (5 Poise) or less at 60 °C and comprising (a) an epoxy resin with a naphthalene backbone, represented by chemical formula (3), (4) or (5) or an epoxy resin with an anthracene backbone, such as diglycidyl ether of anthracene diol and triglycidyl ether of anthracene triol; (wherein "n" and "m" are 1, 2 or 3); (wherein "m" is 0,1 or 2; "n", "n"' and "n"" are 1, 2, 3 or 4; and the groups with "n", "n'" and "n"" may satisfactorily be attached independently to either one ring or both two rings of each of the naphthalene rings); (wherein R is an alkyl group with 1 to 10 carbon atoms; "m" is 0,1 or 2; "n" is 1, 2 or 3; "1" and "1"' are 1, 2, 3 or 4; and the groups with "n", "1" and "1'" may satisfactorily be attached independently to either one ring or both two rings of each of the naphthalene rings); (b) a bifunctional epoxy resin containing two p-(2,3-epoxypropoxy)phenyl groups; (c) an acid anhydride curing agent; and (d) a metal acetonate curing catalyst represented by the chemical formula (2) at 0.1 to 5 parts by weight per 100 parts by weight of the epoxy resins, wherein the ratio of the number of the epoxy groups used is 1 to 4, the ratio being represented by the following formula: ratio of number of epoxy groups = {[molar number of (b) used] x [number of epoxy groups in 1 mole of (b)]} ÷ {[molar number of (a) used] x [number of epoxy groups in 1 mole of (a)]}. The resin composition of claim 1 or 2, produced by a method comprising preliminarily dissolving the curing catalyst (d) in a part of the polyfunctional epoxy resin (a) under heating and dissolving then the remaining components therein. An electrically insulated coil produced by winding an insulating tape base material around a conductor formed into a defined coil shape and impregnating and curing the material with the thermosetting resin composition of any of claims 1 to 3. A stator of rotating machine, produced by a method comprising incorporating into an iron core slot an electrically insulated coil produced by winding an insulating tape base material around a conductor formed into a defined coil shape, inserting a wedge into the external circumference groove of the iron core slot to connect the electrically insulated coil to the external end part of the iron core, and thereafter impregnating and curing the electrically insulated coil and the iron core slot at their integrated state with the thermosetting resin composition of any of claims 1 to 3. A stator of rotating machine according to claim 5, wherein as the insulating tape base material, use is made of an insulating tape base material with a heat conductivity as high as 0.3 to 0.8 W/mK. A stator of rotating machine, produced by a method comprising incorporating, into an iron core slot, an electrically insulated coil produced by winding an insulating tape base material around a stack of insulated conductor formed into a defined coil shape together with a semi electrical conductive slot liner, inserting a wedge into the external circumference groove of the iron core slot to connect the electrically insulated coil to the external end part of the iron core, and thereafter impregnating and curing the electrically insulated coil and the iron core slot at their integrated state with the thermosetting resin composition of any of claims 1 to 3, wherein as the semi electrical conductive slot liner, use is made of a highly heat-conductive, semiconductive slot liner with a heat conductivity as high as 0.3 to 1.0 W/mK and surface resistance of 0.2 to 100 kΩ. A stator of rotating machine according to claim 7, wherein as the insulating tape base material, use is made of an insulating tape base material with a heat conductivity as high as 0.3 to 0.8 W/mK. A rotating machine comprising a stator and a rotor, produced by a method comprising incorporating into an iron core slot an electrically insulated coil produced by winding an insulating tape base material around a stack of insulated conductor formed into a defined coil shape, inserting a wedge into the external circumference groove of the iron core slot to connect the electrical insulating coil to the external end part of the iron core, and thereafter impregnating and curing the electrically insulated coil and the iron core slot at their integrated state with the thermosetting resin composition of any of claims 1 to 3. A stator of rotating machine according to claim 7, wherein as the insulating tape base material, use is made of an insulating tape base material of corona-resistant polyimide film. A rotor of rotating machine, produced by a method comprising impregnating and curing an electrically insulated coil produced by winding an insulating tape base material around a stack of insulated conductor formed into a defined coil shape with the thermosetting resin composition of any of claims 1 to 3, wherein as the insulating tape base material, use is made of an insulating tape base material of corona-resistant polyimide film. A method for producing a stator of rotating machine, comprising incorporating into an iron core slot an electrically insulated coil produced by winding an insulating tape base material around a stack of insulated conductor formed into a defined coil shape together with a semi electrical conductive slot liner, inserting a wedge into the external circumference groove of the iron core slot to connect the electrical insulating coil to the external end part of the iron core, and thereafter impregnating and curing the electrically insulated coil and the iron core slot at their integrated state with the thermosetting resin composition of any of claims 1 to 3, wherein as the insulating tape base material, use is made of an insulating tape base material with a heat conductivity as high as 0.3 to 0.8 W/mK; and wherein as the semi electrical conductive slot liner, use is made of a highly heat-conductive, semi electrical conductive slot liner with a heat conductivity as high as 0.3 to 1.0 W/mK and surface resistance of 0.2 to 100 kΩ.

Inventors: KANO IKUSHI, KASHIWAMURA YOSHIKIYO, KOYAMA TOHRU, MARUYAMA SHOICHI, SUGAWARA KATSUO, KANO, IKUSHI, KASHIWAMURA, YOSHIKIYO, KOYAMA, TOHRU, MARUYAMA, SHOICHI, SUGAWARA, KATSUO
Applicants: HITACHI LTD, HITACHI, LTD.
Application year: 1997
Main classification: C08G59
IPC codes: C08L63, C08G59, H01B3, H02K3, H02K15