One-part electrical-insulating resin composition comprising an epoxy resin

Claim 1

A ONE-PART LIQUID ELECTRICAL-INSULATING RESINCOMPOSITION WHICH IS STABLE FOR MONTHS AT ROOM TEMPERATURE AND CURES UPON HEATIG TO A STRONG,FLEXIBLE, HEAT-RESISTANT, INFUSIBLE, INSOLUBLE STATE, SAID RESIN COMPOSITION COMPRISING A BLEND OF (1) A BRANCHED-CHAIN, ACID-TERMINATED POLYESTER OF DICARBOXYLIC ACID, DIHYDROXY ALCOHOL AND A POLYFUNCTIONAL COMPOUND SELECTED FROM THE CLASS CONSISTING OF POLYHYDRIC ALCOHOLS HAVING AT LEAST THREE NONTERTIARY HYDROXYL GROUPS AND POLYBASIC ACIDS HAVING AT LEAST THREE CARBOXYL GROUPS, FROM 2 TO 8 PERCENT OF THE TOTAL OF SAID ACIDS AND ALCOHOLS CONTAINING AROMATIC RINGS, WHICH POLYESTER CONTAINS AN AVERAGE OF 2.1 TO 3.0 CARBOXYL GROUPS PER MOLECULE, HAS AN ACID NUMBER OF 20-155, A HYDROXYL NUMBER OF LESS THAN 10, IS FREE FROM ETHYLENIC UNSATURATION IN ITS SKELETAL CHAIN, AND HAS A VISCOSITY OF 23*C. OF LESS THAN 300,000 CENTIPOISES, (2) AN EPOXY RESIN CONTAINING AT LEAST 1.5 OXIRANE GROUPS PER AVERAGE MOLECULAR WEIGHT, THE SKELETAL BACKBONE CHAIN OF WHICH IS FREE FROM OTHER THAN OXYGEN AND CARBON ATOMS, AND (3) A CATALYST SELECTED FROM THE GROUP CONSISTING OF 0.01-0.5% HYDRATED TIN TETRACHLORIDE AND 0.5-4% DICYANDIAMIDE, THE PERCENTAGE OF CATALYST BEING BASED ON THE TOTAL INGREDIENTS (1) PLUS (2), SAID BLEND CONTAINING ABOUT 0.8 TO 2 EPOXY GROUPS PER CARBOXYL GROUP, AND THE EPOXY RESIN BEING SO SELECTED THAT A SIMPLE MIXTURE OF INGREDIENTS (1), (2) AND (3) DOES NOT EXCEED 300,000 CENTIPOISES IN VISCOSITY AT 23*C.