Heat resistant electrical insulating varnish

Claim 1

A HIGH TEMPERATURE ELECTRICAL INSULATING VARNISH COMPOSITION COMPRISING IN ADMIXTURE (A) FROM 25% TO 75% BY WEIGHT OF AN ALKYD RESIN DERIVED BY ADMIXING AND HEATING TO A TEMPERATURE IN THE RANGE OF 200*C. TO 240* C. (1) AT LEAST ONE DIBASIC ACID SELECTED FROM THE GROUP CONSISTING OF ISOPHTHALIC ACID, WITH (2) AN ALIPHATIC METHYL ESTERS OF TEREPHTHALIC ACID, WITH (2) AN ALIPHATIC POLYHYDRIC ALCOHOL AND (3) A DRYING OIL, SAID REACTANTS BEING EMPLOYED IN SUCH PROPORTIONS THAT THE DRYING OIL CONSTITUTES 40% TO 55% BY WEIGHT OF THE TOTAL WEIGHT OF ALKYD RESIN, AND SAID ALKYD RESIN BEING REACTED TO AN ACID NUMBER IN THE RANGE OF 4 TO 15 (B) FROM 75% TO 25% BY WEIGHT OF A PHENOL RESIN DERIVED BY ADMIXING AND HEATING TO A TEMPERATURE WITHIN THE RANGE OF 70*C. TO REFLUX (1) FROM 90 TO 80 MOL PERCENT OF PARATERTIARY BUTYL PHENOL, (2) FROM 10 TO 20 MOL PERCENT OF DIPHENYLOL PROPANE, AND (3) FROM 1.5 TO 2 MOLS OF AN ALDEHYDE SELECTED FROM THE GROUP CONSISTING OF FORMALDEHYDE AND POLYMERS OF FORMALDEHYDE IN THE PRESENCE OF FROM 0.2% TO 5% BASED ON THE WEIGHT OF THE PHENOLS, OF AN ALKALI METAL HYDROXIDE, THE AQUEOUS REACTION PRODUCT THEN BEING NEUTRALIZED AND RENDERED ACIDIC WITH AN ACID TO A PH IN THE RANGE OF 4 TO 7, REMOVING THE WATER FROM THE ACIDIFIED REACTION PRODUCT BY EVACUATION, HEATING AND MAINTAINING THE PRODUCT AT A TEMPERATURE OF 135*C. TO 140*C. UNTIL A BALL AND RING SOFTENING TEMPERATURE OF 100*C. IS OBTAINED, AND THEN ADMIXING MALEINIZED LINSEED OIL THEREWITH IN SUCH PROPORTION THAT THERE IS 25 GALLONS TO 40 GALLONS OF MALEINIZED LINSEED OIL PER 100 POUNDS OF REACTION PRODUCT, SAID MALEINIZED LINSEED OIL BEING THE REACTION PRODUCT OF 100 PARTS OF LINSEED OIL AND FROM 3 TO 8 PARTS OF MALEIC ANHYDRIDE AT A TEMPERATURE OF FROM 240*C. TO 270*C. FOR NOT MORE THAN 4 HOURS UNTIL AN ADDUCT IS PRODUCED, AFTER WHICH AN ALIPHATIC POLYHYDRIC ALCOHOL IS ADMIXED IN AN AMOUNT TO FURNISH FROM 1 TO 1.1 HYDROXYL GROUPS FOR EACH MALEIC ANHYDRIDE MOLECULE PRESENT IN THE ADDUCT, THE POLYHYDRIC ALCOHOL HAVING NO OTHER REACTIVE GROUPS THAN THE HYDROXYL GROUPS, AND AN ESTERIFYING REACTION BETWEEN THE POLYHYDRIC ALCOHOL AND THE MALEIC ANHYDRIDE RADICALS IN THE ADDUCT IS EFFECTED BY HEATING THE MIXTURE AT A TEMPERATURE UP TO 270*C. FOR AT LEAST ONE HOUR.