Composite tooling for composites manufacture
AssigneeE. I. Du Pont de Nemours and Company
InventorDipak Gupta
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Abstract
Composite tooling of carbon fiber reinforced polyimide of high Tg is prepared by first curing in an autoclave followed by post-curing in an air circulating oven.
Claims4
A method for preparing a composite tool suitable for fabricating composite articles of high Tg comprising forming a lay-up of prepregs containing carbon fiber reinforcement and substantially stoichiometric quantities of a mixture of diamines consisting essentially of about 95% p-phenylene diamine with the remainder m-phenylene diamine and 2,3-bis-(3',4'-dicarboxyphenyl)hexafluoropropanol in an amount sufficient to produce 35 to 45 volume % of polyimide in the prepreg upon curing, enclosing the lay-up in a vacuum bag, heating the lay-up to a temperature in the range of about 650.degree. to 730.degree. F. while pulling a vacuum on the contents of the bag and while applying a pressure on the bag at least 180 pounds per square inch to cure the assembly until the Tg of the composite tool is between 650.degree. and 700.degree. F., releasing the pressure and vacuum and post curing the assembly to increase Tg by heating in a recirculating air oven to a temperature of at least 700.degree.-725.degree. F. until the Tg of the composite tool reaches at least 730.degree. F.
A composite tool for manufacture of fiber reinforced high temperature composite parts comprising from 35 to 45 volume % of a polyimide consisting essentially of the following recurring structural units:
- ##STR2## wherein A is present in an amount of about 95% an d B the remainder, and from 55 to 65 volume % of carbon fiber reinforcement, said tool having a porosity of less than 6% and a Tg of at least 730.degree. F.
Dependencies are inferred from the claim text.