Methods for altering the impact strength of noncellular thermoplastic materials

Patent metadata

Field	Value
Publication number	US-9481774-B2
Application number	US-4727008-A
Country	US
Kind code	B2
Filing date	Mar 12, 2008
Priority date	Mar 12, 2007
Publication date	Nov 1, 2016
Grant date	Nov 1, 2016

Abstract

Methods for reducing the density of thermoplastic materials and the articles made therefrom having similar or improved mechanical properties to the solid or noncellular material. Also disclosed are improvements to foaming methods and the cellular structures of the foams made therefrom, and methods for altering the impact strength of solid or noncellular thermoplastic materials and the shaping of the materials into useful articles.

First claim

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. A method for increasing the impact strength of a thermoplastic material, comprising:
(a) selecting to increase impact strength of a thermoplastic material and setting a pressure of at least 1 MPa of an environment based on the thermoplastic material in which to perform absorption of an inert gas into the thermoplastic material to cause an increase in the impact strength;
(b) thereafter, absorbing the inert gas within the thermoplastic material at the set pressure; and
(c) treating the thermoplastic material from step (b) at a lower pressure for a sufficient period of time to allow full desorption of the gas from the thermoplastic material to produce a non-cellular thermoplastic material having an increased impact strength.

2. The method of claim 1 , wherein the thermoplastic material is an amorphous or semi-crystalline polymer.

3. The method of claim 1 , wherein the thermoplastic material is polyetherimide and the polyetherimide absorbs the inert gas at a pressure of about 5 MPa.

4. The method of claim 1 , wherein the lower pressure is ambient atmospheric pressure.

5. The method of claim 1 , further comprising shaping the thermoplastic material during treating the material at a lower pressure.

6. The method of claim 5 , wherein the thermoplastic material comprises absorbed gas during shaping.

7. The method of claim 1 , further comprising shaping the thermoplastic material after treating the material at a lower pressure.

8. The method of claim 7 , wherein the thermoplastic material is desorbed of gas during shaping.

9. The method of claim 1 , further comprising placing more than one thermoplastic material in a pressure vessel and interleaving a porous material between thermoplastic materials.

10. The method of claim 1 , further comprising assembling the non-cellular thermoplastic material with increased impact strength into an article.

11. The method of claim 1 , wherein the thermoplastic material is a thermoplastic urethane, thermoplastic elastomer, polyethylene naphthalate, polyetherimide, polyetheretherketone, polyphenylene, sulfone, polyamide-imide, polysulfone, polyphenylsulfone, polyethersulfone, polyphthalamide, polyarylamide, polyphenylene sulfide, cyclic olefin copolymer, polyphthalate carbonate, polycarbonate, polyvinylidene chloride, polyurethane, polyphenylene oxide, poly (acrylonitrile-butadiene-styrene), polymethylmethacrylate, crosslinked polyethylene, polystyrene, styrene acrylonitrile, polyvinyl chloride, polybutylene terephthalate, polyethylene terephthalate, polyoxymethylene, polyacetal, polyamide, polyolefin, polyethylene, or polypropylene.

12. The method of claim 1 , wherein the thermoplastic material is polycarbonate and the polycarbonate absorbs the inert gas at a pressure of 1 MPa to 7 MPa.

13. The method of claim 1 , wherein the non-cellular thermoplastic material is a shaped thermoplastic material.

14. The method of claim 1 , wherein the non-cellular thermoplastic material produced in step (c) has a density substantially the same as an initial density of the non-cellular thermoplastic material in step (a).

15. The method of claim 1 , wherein the inert gas is carbon dioxide.

Assignees

• Miller Dustin
• Kumar Vipin
• Univ Washington

Inventors

• Miller Dustin
• Kumar Vipin

Classifications

• B29C44/10 Primary

  Applying counter-pressure during expanding · CPC title

• C08J9/00 Primary

  Working-up of macromolecular substances to porous or cellular articles or materials; After-treatment thereof (mechanical aspects of shaping of plastics or substances in a plastic state for the production of porous or cellular articles B29C) · CPC title

• B29K2995/0039

  Amorphous · CPC title

• B29K2995/004

  Semi-crystalline · CPC title

• B29C44/5609

  Purging of residual gas, e.g. noxious or explosive blowing agents · CPC title