Methods of preparing polyimides and artifacts composed thereof
AssigneeInternational Harvester Company
InventorsJohn Gagliani, Raymond Lee, Anthony L. Wilcoxson
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Abstract
Methods of converting essentially unpolymerized precursors into polyimides in which the precursors are exposed to microwave radiation. Preheating, thermal post-curing, and other techniques may be employed to promote the development of optimum properties; and reinforcements can be employed to impart strength and rigidity to the final product. Also disclosed are processes for making various composite artifacts in which non-polymeric precursors are converted to polyimides by using the techniques described above.
Claims37
A method of preparing a polyimide from a non-polymeric precursor comprising an ester of a tetracarboxylic acid and one or more primary diamines which includes the step of exposing said precursor to microwave radiation having a frequency of at least 915 mHz for periods of sufficient duration to develop a cellular physical structure and to at least partially develop a polyimide chemical structure.
A method of preparing a polyimide as defined in claim 5 wherein the microwave radiation to which the precursor is exposed has a frequency of about 2450 mHz.
A method of preparing a polyimide with a cellular structure which comprises the steps of:
- forming a primary diamine, 3,3',4,4'-benzophenonetetracarboxylic acid ester solution by dissolving one or more diamines and the aforesaid acid or an anhydride thereof in a lower alkyl alcohol;
- atomizing said solution;
- drying the droplets obtained by atomizing the diamine, ester solution with a heated gas to form a dry, particulate, non-polymeric precursor;
- and exposing said precursor to microwave radiation having a frequency of at least 915 mHz for periods of sufficient duration to develop a cellular physical structure and to at least partially develop a polyimide chemical structure.
A method of preparing a polyimide from a precursor containing substantially equimolar amounts of a half ester of 3,3',4,4'-benzophenonetetracarboxylic acid and one or more primary diamines, said process including the step of exposing said precursor to microwave energy having a frequency of at least 915 mHz for a period of sufficient duration to develop a cellular physical structure and to at least partially develop a polymeric chemical structure.
Dependencies are inferred from the claim text.