HARZE MIT GERINGER THERMISCHER AUSDEHNUNG.

摘要

Polyamide-imides of low thermal expansivity having a repeating structural unit of the general formula (I) in which Ar is a tetravalent aromatic group, A is -NHCO-, R1 through R3 are alkyl, alkoxy, or halogen, l , m, and n are integers from 0 to 4, x is 0 or 1, and y is an integer indicating the number of repeating units and in which at least one alkoxy group is present, show improved mechanical (for example, flexibility) and adhesive properties and low water absorption and are useful for the manufacture of flexible base materials for printed circuit boards, etc.