Polyimide with reduced anhydride content
AssigneeThe Dexter Corporation
InventorDavid S. Darrow
Life of this patent
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Abstract
Polyimide resins, which have reduced anhydride content when molded, are prepared by a novel reaction process that includes reacting an esterified aromatic tetracarboxylic acid or anhydride monomer with a primary aromatic diamine until substantially no free monomer remains to form a polyamide-acid (the molar ratio of esterified monomer to diamine ranging from 1:1 to 1:2); reacting the polyamide-acid with a low molecular weight end-capping agent to form an end-capped polyamide-acid; and heating the end-capped polyamide-acid to form the polyimide.
Claims19
A method of preparing a polyimide comprising the steps of
- esterifying an aromatic tetracarboxylic acid or anhydride monomer with one or more alkyl alcohols to convert one or two of the carboxylate groups of said acid or anhydride to ester groups;
- reacting the esterified monomer with a primary aromatic diamine until substantially no free monomer remains to form a polyamide-acid,
- the molar ratio of said esterified monomer to said diamine ranging from 1:1 to 1:2;
- reacting said polyamide-acid with a low molecular weight monomeric end-capping agent to form an end-capped polyamide-acid;
- and
- heating said end-capped polyamide-acid to form said polyimide.
A method of preparing a polyimide comprising the steps of
- esterifying 3,3'-4,4'-benzophenone tetracarboxylic acid or anhydride monomer with methyl alcohol to convert one or more of the carboxylate groups of said acid or anhydride to methyl ester groups;
- reacting the esterified monomer with methylene dianiline until substantially no free monomer remains to form a polyamide-acid,
- the molar ratio of said esterified monomer to said methylene dianiline ranging from 1:1 to 1:2;
- reacting said polyamide-acid with a monomeric norbornene ester to form an end-capped polyamide-acid;
- and
- heating said end-capped polyamide-acid to form said polyimide.
Dependencies are inferred from the claim text.