Various embodiments may include a solid insulation material, e.g. in tape form, the use thereof in a vacuum impregnation process, and/or an insulation system produced therewith and also an electrical machine having the insulation system, for the medium- and high-voltage sector. Some examples include rotating electrical machines in the medium- and high-voltage sector and also semifinished products for electrical switchgear. The solid insulation material and the insulation system produced therewith are characterized in that it can be produced in an anhydride-free manner, wherein the curing catalyst is, for example, an adduct of a 1H-imidazole and/or 1H-imidazole derivative with a compound containing oxirane groups.

Disclosed is an anhydride-free insulation system for current-carrying construction parts of an electric engine which comprises:

(A) a mica paper or mica tape for wrapping parts of said electric engine that are potentially current-carrying during operation of the engine, which mica paper or mica tape is impregnable via vacuum pressure impregnation with a thermally curable epoxy resin formulation and comprises a thermally activatable curing initiator for the epoxy resin formulation consisting of one or more quarternary ammonium salts of an aromatic-heterocyclic compound, which contains 1 or 2 nitrogen atoms, and a complex anion selected from the group consisting of BF.sub.4.sup., PF.sub.6.sup., SbF.sub.6.sup., SbF.sub.5(OH).sup., AsF.sub.6.sup. and Al[OC(CF.sub.3).sub.3].sub.4.sup. in an amount sufficient to cure the epoxy resin taken up by the mica paper or mica tape and the construction part of the engine during the vacuum pressure impregnation step;

(B) a thermally curable bath formulation for the vacuum pressure impregnation comprising one or more epoxy resins, which formulation is substantially or, preferably, entirely free of a thermally activatable curing initiator for the epoxy resin formulation, in particular of quarternary ammonium salts of aromatic-heterocyclic compounds containing 1 or 2 nitrogen atoms, and of a complex anion selected from the group consisting of BF.sub.4.sup., PF.sub.6.sup., SbF.sub.6.sup., SbF.sub.5(OH).sup., AsF.sub.6.sup. and [Al(OC(CF.sub.3).sub.3).sub.4] and

(C) one or more co-initiator for the thermally activatable curing initiator selected from a diarylethane derivative of formula:

##STR00001##

wherein Ar is phenyl, naphthyl, or C.sub.1-C.sub.4alkyl- or chloro-substituted phenyl, R1 is hydroxy, C.sub.1-C.sub.4alkoxy, OCOR3 or OSiR4R5R6, wherein R3 is C.sub.1-C.sub.8alkyl or phenyl, and R5, R5 and R6 are each independently of one another C.sub.1-C.sub.4alkyl or phenyl, and R2 is C.sub.1-C.sub.4alkyl or cyclohexyl or has the same meaning as Ar, wherein one or more of said co-initiators may be contained in the mica paper or mica tape (A) of the system and/or one or more of said co-initiators may be contained in the a thermally curable epoxy resin bath formulation (B) of the system and is present in said mica paper or mica tape (A) thermally curable epoxy resin bath formulation (B) in an overall amount sufficient to cure the epoxy resin taken up by the mica paper or mica tape and the construction part of the engine during the vacuum pressure impregnation step after said step.

Disclosed is an anhydride-free insulation system for current-carrying construction parts of an electric engine which comprises:

(A) a mica paper or mica tape for wrapping parts of said electric engine that are potentially current-carrying during operation of the engine, which mica paper or mica tape is impregnable via vacuum pressure impregnation with a thermally curable epoxy resin formulation and comprises a thermally activatable curing initiator for the epoxy resin formulation consisting of one or more quarternary ammonium salts of an aromatic-heterocyclic compound, which contains 1 or 2 nitrogen atoms, and a complex anion selected from the group consisting of BF.sub.4.sup., PF.sub.6.sup., SbF.sub.6.sup., SbF.sub.5(OH).sup., AsF.sub.6.sup. and Al[OC(CF.sub.3).sub.3].sub.4.sup. in an amount sufficient to cure the epoxy resin taken up by the mica paper or mica tape and the construction part of the engine during the vacuum pressure impregnation step;

(B) a thermally curable bath formulation for the vacuum pressure impregnation comprising one or more epoxy resins, which formulation is substantially or, preferably, entirely free of a thermally activatable curing initiator for the epoxy resin formulation, in particular of quarternary ammonium salts of aromatic-heterocyclic compounds containing 1 or 2 nitrogen atoms, and of a complex anion selected from the group consisting of BF.sub.4.sup., PF.sub.6.sup., SbF.sub.6.sup., SbF.sub.5(OH).sup., AsF.sub.6.sup. and [Al(OC(CF.sub.3).sub.3).sub.4] and

(C) one or more co-initiator for the thermally activatable curing initiator selected from a diarylethane derivative of formula:

##STR00001##

wherein Ar is phenyl, naphthyl, or C.sub.1-C.sub.4alkyl- or chloro-substituted phenyl, R1 is hydroxy, C.sub.1-C.sub.4alkoxy, OCOR3 or OSiR4R5R6, wherein R3 is C.sub.1-C.sub.8alkyl or phenyl, and R5, R5 and R6 are each independently of one another C.sub.1-C.sub.4alkyl or phenyl, and R2 is C.sub.1-C.sub.4alkyl or cyclohexyl or has the same meaning as Ar, wherein one or more of said co-initiators may be contained in the mica paper or mica tape (A) of the system and/or one or more of said co-initiators may be contained in the a thermally curable epoxy resin bath formulation (B) of the system and is present in said mica paper or mica tape (A) thermally curable epoxy resin bath formulation (B) in an overall amount sufficient to cure the epoxy resin taken up by the mica paper or mica tape and the construction part of the engine during the vacuum pressure impregnation step after said step.

An insulating tape having a mica layer, a reinforcing layer having a filler and a fiber reinforcing material laminated on the mica layer, and a cellulose derivative layer laminated on the reinforcing layer is provided. One or more hydroxyl groups in the glucose units of the cellulose derivative are substituted with a functional group such as CH.sub.2CH.sub.2OH or (CH.sub.2CH.sub.2O).sub.pH (where p is any repeating number up to 50). The weight per unit area of the mica ranges from 100 g/m.sup.2 to 200 g/m.sup.2. The filler has a maximum particle size of 100 m or smaller and a weight per unit area ranging from 10 g/m.sup.2 to 50 g/m.sup.2. The insulating tape is useful to form a stator coil insulating layer with high thermal conductivity, with no outflow of a filler to the exterior during production of the stator coil, and with enhanced bonding strength.

An insulating tape having a mica layer, a reinforcing layer having a filler and a fiber reinforcing material laminated on the mica layer, and a cellulose derivative layer laminated on the reinforcing layer is provided. One or more hydroxyl groups in the glucose units of the cellulose derivative are substituted with a functional group such as CH.sub.2CH.sub.2OH or (CH.sub.2CH.sub.2O).sub.pH (where p is any repeating number up to 50). The weight per unit area of the mica ranges from 100 g/m.sup.2 to 200 g/m.sup.2. The filler has a maximum particle size of 100 m or smaller and a weight per unit area ranging from 10 g/m.sup.2 to 50 g/m.sup.2. The insulating tape is useful to form a stator coil insulating layer with high thermal conductivity, with no outflow of a filler to the exterior during production of the stator coil, and with enhanced bonding strength.

An impregnable electrical insulating paper for an electrical insulating body having first platelet-shaped particles which have layer silicates, and second platelet-shaped particles which have a heat conductivity at 20 C. of at least 1 W/mK. A method for producing an impregnable electrical insulating paper, an electrical insulating tape, an electrical insulating body, and the use of the electrical insulating body having first platelet-shaped particles which have layer silicates, and second platelet-shaped particles.

A fire-resistive cable system comprises an electrical cable housed in a fiberglass-reinforced thermosetting resin conduit. The electrical cable comprises a conductor and has only one couple of mica tapes surrounding the conductor. The couple of mica tapes are formed of a first mica tape and a second mica tape wound around the first mica tape. The mica layer of the first mica tape faces and contacts the mica layer of the second mica tape. The fiberglass-reinforced thermosetting resin conduit is made of a material comprising fibers of a glass selected from E-glass and E-CR-glass, and a resin.

A fire-resistive cable system comprises an electrical cable housed in a fiberglass-reinforced thermosetting resin conduit. The electrical cable comprises a conductor and has only one couple of mica tapes surrounding the conductor. The couple of mica tapes are formed of a first mica tape and a second mica tape wound around the first mica tape. The mica layer of the first mica tape faces and contacts the mica layer of the second mica tape. The fiberglass-reinforced thermosetting resin conduit is made of a material comprising fibers of a glass selected from E-glass and E-CR-glass, and a resin.

Laminate structure suitable for use as electrical insulation comprising: a) a corona-resistant layer comprising 90 to 99 weight percent uniformly distributed calcined mica and 1 to 10 weight percent aramid material, the aramid material being in the form of floc, fibrid, or mixtures thereof; b) a support layer comprising unidirectional or woven filament yarns, the support layer having a first and second face; and c) a resin-compatible layer comprising 60 to 80 weight percent uniformly distributed uncalcined mica and 20 to 40 weight percent aramid material, the aramid material being in the form of floc, fibrid, or mixtures thereof; wherein the first face of the support layer is directly bound to the corona-resistant layer and the second face of the support layer is directly bound to the resin-compatible layer; the laminate structure having a total mica content of 60 weight percent or greater.

Laminate structure suitable for use as electrical insulation comprising: a) a corona-resistant layer comprising 90 to 99 weight percent uniformly distributed calcined mica and 1 to 10 weight percent aramid material, the aramid material being in the form of floc, fibrid, or mixtures thereof; b) a support layer comprising unidirectional or woven filament yarns, the support layer having a first and second face; and c) a resin-compatible layer comprising 60 to 80 weight percent uniformly distributed uncalcined mica and 20 to 40 weight percent aramid material, the aramid material being in the form of floc, fibrid, or mixtures thereof; wherein the first face of the support layer is directly bound to the corona-resistant layer and the second face of the support layer is directly bound to the resin-compatible layer; the laminate structure having a total mica content of 60 weight percent or greater.