REINFORCED POLYQUINOXALINE GASKET AND METHOD OF PREPARING THE SAME

• US 3,790,432 A
• Filed: 12/30/1971
• Issued: 02/05/1974
• Est. Priority Date: 12/30/1971
• Status: Expired due to Term

• Current Assignee: Fletcher James C Administrator of The National Aeronautics and Space Administration With Respect To An Invention of, N/a,, Richard Van Auken
• Original Assignee: Fletcher James C Administrator of The National Aeronautics and Space Administration With Respect To An Invention of, N/a,, Richard Van Auken
• Inventors: Van Auken, Richard, Fletcher, James C. Administrator of the National Aeronautics and Space, N/a,
• Primary Examiner(s): Lesmes, George F.
• Assistant Examiner(s): McCamish, M. E.
• Application Number:
  US05/214,006
• Time in Patent Office: 768 Days
• Field of Search: 161/93,42,43,182,192 260/2R 156/331 264/88,135,136,257
• US Class Current: 428/76
• CPC Class Codes: B29C 70/003 characterised by the matrix material, e.g. material composition or physical properties
• CPC Class Codes: B29K 2309/08 Glass
• CPC Class Codes: B32B 2262/101 Glass fibres
• CPC Class Codes: B32B 2581/00 Seals; Sealing equipment; Gaskets
• CPC Class Codes: B32B 27/08 of synthetic resin
• CPC Class Codes: B32B 27/12 next to a fibrous or filamentary layer
• CPC Class Codes: Y10T 428/215 Seal, gasket, or packing
• CPC Class Codes: Y10T 428/239 Complete cover or casing
• CPC Class Codes: Y10T 428/264 Up to 3 mils
• CPC Class Codes: Y10T 428/269 including synthetic resin or polymer layer or component
• CPC Class Codes: Y10T 442/67 Multiple nonwoven fabric layers composed of the same inorganic strand or fiber material

Abstract

A gasket or seal resistant to ionizing radiation and liquid hydrogen temperatures is made up of a laminated polyquinoxaline resin-fiberglass cloth body portion and a molded polyquinoxaline encapsulating film. The laminated body is prepared by stacking thin sheets of the resin alternately with fiberglass cloth and heating the assembly under pressure with the temperature, pressure and resin film thickness being controlled so that only partial impregnation of the fiberglass cloth is produced. The encapsulating resin film is preheated at about 300* F and applied to the laminate body by molding at a temperature of about 625* F, after which the molded gasket is deflashed and postcured by heating at 675* to 700* F.

Claims

2. The gasket of claim 1 wherein said layers of resin in said laminated body are 1.8 to 2.2 mils thick.

3. The method of preparing a gasket which comprises:

a. stacking alternating sheets of uncured polyquinoxaline resin and fiberglass cloth;

b. heating the resulting stacked array at a temperature of 340* to 360* F while compressing said sheets together at a pressure of 25 to 35 psi to form a partially impregnated, laminated body;

c. covering the entire surface of said body with a film of polyquinoxaline resin, said film having been heated to a temperature of 280* to 320* F;

d. molding the film covered body at a temperature of 600* to 650* F and a pressure of 25 to 35 psi;

e. post-curing the molded gasket body by heating at a temperature of 675* to 700* F.

4. The method of claim 3 wherein said polyquinoxaline has the formula

5. The method of claim 4 wherein the thickness of said resin sheet in said array is 1.8 to 2.2 mils.

6. The method of claim 5 wherein a portion of said body is cut away to leave only a gasket blank prior to covering the body surface with said film.

7. The method of claim 6 wherein said film is at least 3.5 mils thick.

8. The method of claim 6 wherein said molded body is deflashed prior to post curing.

9. The method of claim 6 wherein stacked array is heated at a temperature of about 350* F and a pressure of about 30 psi.

10. The method of claim 6 wherein said body is molded at a temperature of about 625* F and a pressure of about 30 psi.