Mixed polyimides and process for preparing them

Details Mixed polyimides and process for preparing them Mixed polyimides and process for preparing them

1990-06-29

1991-11-19

Welsh, Maurice J.

Synthetic resins or natural rubbers -- part of the class 520 ser

Synthetic resins

From reactant having at least one -n=c=x group as well as...

528 57, 528 67, 528 73, 528336, 528338, 528339, 528340, 528348, C08G 1800

Patent

active

050667602

ABSTRACT:
To produce mixed polyimides having structural units of the general formulae ##STR1## wherein n is an integer larger than 1 and R represents a divalent aromatic residue, a solution of an intramolecular tetracarboxylic acid dianhydride mixture including 50 to 99% by mol benzophenone-3,3',4,4'-tetracraboxylic acid dianhydride and 50 to 1% by mol pyromellitic acid dianhydride is heated in a polar aprotic solvent and is admixed with an altogether equimolar amount of 2,4- and/or 2,6-toluenediisocyanate and/or methylenebis(phenylisocyanate). The mixed polyimides according to the invention are readily soluble in organic solvents, are flame-retardant and exhibit a good thermostability.

REFERENCES:
patent: 3666709 (1972-05-01), Suzuki et al.
patent: 3708458 (1973-01-01), Alberino et al.
patent: 3985934 (1976-10-01), Farrissey, Jr. et al.
patent: 4629777 (1986-12-01), Pfeifer
patent: 4657832 (1987-04-01), Pfeifer
patent: 4801502 (1989-01-01), Weinrotter et al.
patent: 4871500 (1989-10-01), Harms et al.

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