Tape adhesive for an insulating tape in an insulation system and an insulation system

Abstract

Tape adhesives suitable for impregnating processes for insulation systems are described. Embodiments of the tape adhesives include solid insulation material such as mica, anhydride-free impregnating resins and accelerators for the anhydride-free impregnating resins. The tape adhesives may be adjusted with respect to the reactivity of the accelerators for the anhydride-free impregnating resins in relation for the storage stability of the overall insulation systems.

Claims

1. An insulation system comprising a solid insulation material, an anhydride-free impregnating resin, an accelerator, and an oxirane group free tape adhesive having a viscosity of about 5 to about 20 Pa*s at about 70 C., wherein the tape adhesive comprises an addition product formed from an A(OH).sub.n segment comprising bisphenols, diols, triols, and/or higher alcohols, with a Cy segment comprising at least one compound selected from the group consisting of a cyclohexene oxide and a cyclohexene oxide derivative.

2. The system of claim 1, wherein the accelerator comprises a tri-N-methylpiperazine derivative of trimethylolpropane trimethacrylate.

3. The system of claim 1, wherein the tape adhesive is present together with the accelerator in a blend, wherein the blend comprises from about 50% to about 99.5% tape adhesive by weight.

4. The system of claim 1, wherein the tape adhesive is present together with the accelerator in a blend, wherein the blend comprises from about 60% to about 95% tape adhesive by weight.

5. The system of claim 1, wherein the tape adhesive is present together with the accelerator in a blend, wherein the blend comprises from about 70% to about 90% tape adhesive by weight.

6. The system of claim 1, wherein the solid insulation material comprises mica.

7. An insulation system comprising a solid insulation material comprising mica, an anhydride-free impregnating resin, an accelerator comprising a tri-N-methylpiperazine derivative of trimethylolpropane trimethacrylate, and an oxirane group free tape adhesive having a viscosity of about 5 to about 20 Pa*s at about 70 C., wherein the tape adhesive comprises an addition product formed from an A(OH).sub.n segment comprising bisphenols, diols, triols, and/or higher alcohols, with a Cy segment comprising at least one compound selected from the group consisting of a cyclohexene oxide and a cyclohexene oxide derivative.

8. The system of claim 7, wherein the tape adhesive is present together with the accelerator in a blend, wherein the blend comprises from about 50% to about 99.5% tape adhesive by weight.

9. The system of claim 7, wherein the tape adhesive is present together with the accelerator in a blend, wherein the blend comprises from about 60% to about 95% tape adhesive by weight.

10. The system of claim 7, wherein the tape adhesive is present together with the accelerator in a blend, wherein the blend comprises from about 70% to about 90% tape adhesive by weight.

Description

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS OF THE INVENTION

(1) In an advantageous embodiment, suitable tape adhesives are compounds which react by a chemical oxirane-hydroxyl reaction with creation of new hydroxyl groups in vicinal positions from cyclohexene oxide and/or monoepoxidic cyclohexene oxide derivatives and diols, triols and/or higher alcohols, alcohol derivatives, esters of aliphatic, cycloaliphatic and/or aromatic nature, and aromatic and cycloaliphatic bisphenols A(OH).sub.n (where A corresponds to the empirical formula radical depleted in a formal sense of n OH groups according to the Lewis empirical formula nomenclature) with n=2 to 20, and after vacuum- and temperature-mediated distillative removal of unreacted cyclohexene oxide or cyclohexene oxide derivative have a viscosity of 1-100 Pa.Math.s at impregnating temperature.

(2) Suitable examples of A(OH).sub.n are: monoethylene glycol (C.sub.2H.sub.4) (OH).sub.2, butanediols (C.sub.4H.sub.8) (OH).sub.2, butenediols (C.sub.4H.sub.6) (OH).sub.2, butynediol (C.sub.4H.sub.4) (OH).sub.2, polyethylene glycols H(OC.sub.2H.sub.4).sub.x (OH).sub.2 with x=1 to 5000, propylene glycol (C.sub.3H.sub.6) (OH).sub.2, polypropylene glycols H(OC.sub.3H.sub.6).sub.x (OH).sub.2 with x=1 to 5000, diethylene glycol (C.sub.2H.sub.8O) (OH).sub.2, propanediols (C.sub.3H.sub.6) (OH).sub.2, neopentyl glycol (C.sub.5H.sub.10) (OH).sub.2, cyclopentanediols (C.sub.5H.sub.8) (OH).sub.2, cyclopentenediols (C.sub.5H.sub.6) (OH).sub.2, glycerol (C.sub.3H.sub.5) (OH).sub.3, pentanediols (C.sub.5H.sub.10) (OH).sub.2, pentaerythritol (C.sub.5H.sub.8) (OH).sub.4, hexanediols (C.sub.6H.sub.12) (OH).sub.2, hexylene glycols (C.sub.6H.sub.12) (OH).sub.2, heptanediols (C.sub.7H.sub.14) (OH).sub.2, octanediols (C.sub.8H.sub.16) (OH).sub.2, polycaprolactonediols, polycaprolactonetriols, hydroquinone (C.sub.6H.sub.4) (OH).sub.2, resorcinol (C.sub.6H.sub.4) (OH).sub.2, (pyro)catechol (C.sub.6H.sub.4) (OH).sub.2, rucinol (C.sub.10H.sub.12) (OH).sub.2, triethylene glycol (C.sub.6H.sub.12) (OH).sub.2, fully aromatic, partly hydrogenated and/or fully hydrogenated bisphenol A (C.sub.15H.sub.14) (OH).sub.2, (C.sub.15H.sub.28) (OH).sub.2, bisphenol F (C.sub.13H.sub.10) (OH).sub.2, bisphenol S (C.sub.12H.sub.8O.sub.2S) (OH).sub.2, tricyclodecanedimethanol (C.sub.12H.sub.18) (OH).sub.2, glycerol carbonate (C.sub.4H.sub.5) (OH).sub.1.

(3) In a preferred embodiment, the tape adhesive has a viscosity of 5-20 Pa*s at about 70 C.

(4) According to some embodiments, compounds suitable as tape adhesives are react with anionically and/or cationically curing accelerator substances for conventional 1,2-diepoxides, especially of bisphenol A diglycidyl ether and/or bisphenol F diglycidyl ether having repeat units n0. According to preferred embodiments, the tape adhesive of the present invention is free of oxirane groups. According to further embodiments, accelerators with relatively high vacuum stability that initiate anionic polymerization, for example tri-N-methylpiperazine derivative of TMPT, give the required storage stability of the mica insulation tape with tape adhesives that are free of oxirane groups.

(5) According to some embodiments of the invention, cyclohexene oxide and/or a cyclohexene oxide derivatized on the aliphatic cycle only have one oxirane group each, the reaction of these epoxy groups with the hydroxyl groups of the A(OH).sub.n segment does not give any cycloaliphatic oxirane groups capable of reaction at a later stage, which can react with anionic and/or cationically mediating accelerator substances in the insulation tape.

(6) According to some embodiments, he synthesis of the tape adhesive substances of the invention is possible, for example, by reaction of the particular A(OH).sub.n reactant with cyclohexene oxide and/or a cyclohexene oxide derivative.

(7) According to some embodiments of the invention, since the reaction of oxiranes and hydroxyls, in terms of chemical mechanism, generates new hydroxyl groups in the target molecule during the oxirane/hydroxyl group reaction, these novel tape adhesive derivatives are additionally also capable of being polymerized into ionically curing, especially phthalic anhydride-free formulations.

(8) Accordingly, the novel tape adhesives of the present invention are likewise also suitable as carriers or encapsulations for ionically active accelerator types, for instance hexafluoroantimonates, tetrafluoroborates and hexafluorophosphates and/or sulfonium derivatives as representatives of what are called superacids or superacid salts, but also for more vacuum-stable alkylmethyl-imidazoles, especially 1-decyl-2-methylimidazole.

(9) According to some embodiments, these show only marginal catalysis, if any, of the bimolecular hydroxyl etherification reaction with compounds containing hydroxyl groups even at elevated temperature around 70 C.

(10) For illustration of the target structures, a few working examples of the tape adhesive compounds usable individually or as a mixture are shown hereinafter in the form of structural formulae:

(11) ##STR00001## ##STR00002## ##STR00003##

(12) According to some embodiments of the invention, the tape adhesive is a substance which is viscous to highly viscous or has solidified in amorphous form at room temperature, which takes the form, for example, of a blend with one or more accelerators that are solid or liquid at room temperature in a content of 50%-99.5% by weight, preferably of 60%-95% by weight, especially preferably of 70%-90% by weight.

(13) The accelerator used may, for example, be an ionically active curing catalyst, for example an organic and/or inorganic superacid or a superacid salt, an alkylimidazole and/or an alkylimidazole derivative, alkylpyrazole and/or an alkylpyrazole derivative etc.

(14) The impregnating agent used in preferred embodiments, is an anhydride-free impregnating resin; for example, the impregnating resin may comprise one or more compounds selected from the group of the following compounds: undistilled and/or distilled, optionally reactively diluted bisphenol A diglycidyl ether, undistilled and/or distilled, optionally reactively diluted bisphenol F diglycidyl ether, hydrogenated bisphenol A diglycidyl ether and/or hydrogenated bisphenol F diglycidyl ether, pure and/or solvent-thinned epoxy novolak and/or epoxy-phenol novolak, cycloaliphatic epoxy resins such as 3,4-epoxycyclohexylmethyl 3,4-epoxycyclohexylcarboxylate, e.g. CY179, ERL-4221; Celloxide 2021P, bis(3,4-epoxycyclohexylmethyl) adipate, e.g. ERL-4299; Celloxide 2081, vinylcyclohexene diepoxide, e.g. ERL-4206; Celloxide 2000, 2-(3,4-epoxycyclohexyl-5,5-spiro-3,4-epoxy)-cyclohexane-meta-dioxane, e.g. ERL-4234; diglycidyl hexahydro-phthalate, e.g. CY184, EPalloy 5200; tetrahydrophthalic acid diglycidyl ether, e.g. CY192; glycidized amino resins N,N-diglycidyl-para-glycidyloxyaniline, e.g. MY0500, MY0510, N,N-diglycidyl-meta-glycidyloxyaniline, e.g. MY0600, MY0610, N,N,N,N-tetraglycidyl-4,4-methylenedianiline, e.g. MY720, MY721, MY725, and any desired mixtures of the aforementioned compounds.

(15) For production of the tape adhesive according to some embodiments, a cyclohexene oxide, a 4-vinylcyclohexene oxide and/or any other cyclohexene derivative having R1R1 radical on the cycloaliphatic ring is reacted with a monoalcohol and/or one divalent and/or two or more higher aliphatic, cycloaliphatic, aromatic and/or heterocyclic alcohols, alkyl/arylalcohol derivatives and/or esters and/or bisphenols A(OH).sub.n where A=(C.sub.xH.sub.y) with preferably x=1-30 and y=1-100, optionally through use of a catalyst K, i.e. n in the range from about 1 to about 5000, preferably about 2-10.

(16) According to preferred embodiments, the present invention for the first time provides a tape adhesive suitable for conventional impregnating processes for an insulation system, comprising solid insulation material such as mica, an anhydride-free impregnating resin and an accelerator for the anhydride-free impregnating resin, wherein the tape adhesive is adjusted with respect to the reactivity of an accelerator or curing catalyst of an anhydride-free impregnating resin in relation to the storage stability of the overall system.