High-solids polyimide precursor solutions
AssigneeThe United States of America as represented by the United States National Aeronautics and Space Administration
InventorChun-Hua Chuang
Life of this patent
Estimating the term…
Abstract
This invention is a highly concentrated stable solution of polyimide precursors (monomers) having a solids content ranging from about 80 to 98 percent by weight in lower aliphatic alcohols i.e. methyl and/or ethyl alcohol. The concentrated polyimide precursor solution comprises effective amounts of at least one aromatic diamine, at least one aromatic dianhydride or a lower molecular weight alkyl ester of said dianhydride, and a monofunctional endcap including monoamines, monoanhydrides and the lower alkyl esters of said monoanhydrides. These concentrated polyimide precursor solutions are particularly useful for the preparation of fibrous prepregs and composites for use in structural materials for military and civil applications.
Claims20
A method of preparing a stable high-solids mixture of polyimide precursors having an improved shelf life, by preventing the premature polymerization and aging of said mixture which comprises preparing a solution of a lower molecular weight alcohol containing effective amounts of at least one aromatic dianhydride, at least one aromatic diamine, and an aromatic monofunctional endcap, and subsequently heating said alcohol solution to obtain a mixture of said solids content ranging from about 85 to 98 percent by weight of said polyimide precursors.
A method of preparing a fibrous prepreg comprising a fibrous material coated or impregnated with an effective amount of a stable high-solids mixture of polyimide precursors;
- said mixture of polyimide precursors derived from a lower molecular weight alcohol solution containing effective amounts of at least one aromatic dianhydride, at least one aromatic diamine, and an aromatic monofunctional endcap;
- said alcohol solution heated to obtain a stable mixture having a solids content ranging from 85 to 98 percent by weight of said polyimide precursors.
Dependencies are inferred from the claim text.