Linear polyurethanes from 2, 2, 4, 4-tetraalkyl-1, 3-cyclobutanediols

Claim 1

A LINEAR POLYURETHANE CONSISTING ESSENTIALLY OF THE FOLLOWING CONSTITUENTS (1) A GLYCOL CONTAINING FROM 2 TO 20 CARBON ATOMS OF WHICH AT LEAST 50 MOLE PERCENT IS AT LEAST ONE OF CIS AND TRANS SIOMERS OF 2,2,4,4-TETRAALKYL1,3-CYCLOBUTANEDIOLS WHEREIN THE ALKYL RADICALS CONTAIN FROM 1 TO 4 CARBON ATOMS AND (2) A BIFUNCTIONAL HYDROCARBON DIISOCYANATE WHEREIN THE HYDROCARBON MOIETY IS SELECTED FROM THE GROUP CONSISTING OF DIVALENT NONFUNCTIONAL AROMATIC AND ALIPHATIC ORGANIC RADICALS CONTAINING FROM 2 TO 25 CARBON ATOMS, SAID POLYURETHANE BEING CHARACTERIZED BY MELTING AT FROM ABOUT 150*-350*C., HAVING AN INHERENT VISCOSITY MEASURED IN DIMETHYLFORMAMIDE OF AT LEAST ABOUT 0.3, BEING CAPABLE OF FORMING FIBER AND HAVING IMPROVED STABILITY TO LOSS OF INHERENT VISCOSITY (A) IN A MOLTEN CONDITION NORMALLY CAUSING THERMAL DEGRADATION AND (B) WHEN FIBERS ARE EXPOSED TO AQUEOUS ALKALINE SOLUTIONS NORMALLY PRODUCING HYDROLYTIC DEGRADATION.