Curing polyester or polycarbonate and polyepoxide with polyorgano phosphorous catalyst

The method of making a latently thermosettable, thermoplastic resin mass which includes the following steps:

• A. selecting a composition which comprises
• (a) an aromatic polyester essentially free of active hydrogens,
• (b) a compatible polyepoxide essentially free of active hydrogens, and
• (c) a catalytically effective amount of a catalyst for the reaction of ester groups in said polyester with oxiranes in said polyepoxide;:
• the number ratio of said oxiranes to said ester groups being within the range of from about 0.8/1 to about 2.25/1,
• and said catalyst being a polyorgano, pentavalent phosphorous salt which, when
• (1) said polyester is a polycarbonate prepared from bisphenol A and phosgene and has a weight average molecular weight of about 24,000,
• (2) said polyepoxide is the diglycidylether of bisphenol A,
• (3) the polycarbonate to polyepoxide ratio by weight is 42.5/57.5 and the amount of said catalyst is 0.015 mmoles per gram of the total weight of polycarbonate and polyepoxide, and
• (4) the polycarbonate, polyepoxide and catalyst are mixed together and the Secant Onset Temperature of the resultant mixture determined,
• results in said temperature being within the range extending from above 125.degree. C. to the highest temperature at which said composition can be melt-processed without deteriorating or prematurely setting up, and
• B. converting a body of said composition, by melt-processing it at or above a first temperature, to a shaped mass which is partially cured to an extent such that if it is cooled as necessary until it solidifies and then reheated, it can be further melt-processed at a temperature higher than said first temperature.