Single-phase solution molding

Patent metadata

Field	Value
Publication number	US-10850434-B2
Application number	US-201815993022-A
Country	US
Kind code	B2
Filing date	May 30, 2018
Priority date	May 31, 2017
Publication date	Dec 1, 2020
Grant date	Dec 1, 2020

Abstract

Aspects hereof provide methods for molding a single-phase solution comprised of a polymer composition and a gas. The polymer composition and the gas are maintained under pressure during the molding operation to prevent a cellular structure from being formed by the dissolved gas in the polymer composition coming out of solution. The mold cavity in which the single-phase solution is introduced for molding purposes is pressurized to a mold pressure that is sufficient to maintain the single-phase solution as a single-phase solution as the mold cavity is filled. Subsequent to filling the mold cavity with the single-phase solution under pressure, the resulting article may solidify entrapping the compressed gas, or the article may be exposed to a reduction in pressure causing the entrapped gas to form a cellular structure.

First claim

The invention claimed is:

1. A method of molding a single-phase solution, the method comprising:
forming the single-phase solution, wherein the single-phase solution is comprised of a polymer composition and a gas;
pressurizing a mold cavity of a mold above atmospheric pressure to a mold pressure, wherein the mold pressure is at least a pressure to maintain the single-phase solution as a single phase;
injecting the single-phase solution into the mold cavity;
maintaining at least the mold pressure in the mold cavity during the injecting of the single-phase solution; and
cooling the single-phase solution below a glass transition temperature of the polymer and gas solution to form a single-phase solid article.

2. The method of claim 1 , wherein forming the single-phase solution comprises dissolving the gas with the polymer composition while the polymer composition is at least at a glass transition temperature.

3. The method claim 1 , wherein forming the single-phase solution comprises dissolving the gas with the polymer composition while the polymer composition is below a glass transition temperature.

4. The method of claim 1 , wherein forming the single-phase solution comprises dissolving the gas with the polymer composition while the gas is in a super-critical fluid state.

5. The method of claim 1 , wherein forming the single-phase solution comprises dissolving the gas with the polymer composition while the gas is above atmospheric pressure.

6. The method of claim 1 , wherein the polymer composition is comprised of a polymer selected from one of polyurethane and ethylene-vinyl acetate.

7. The method of claim 1 , wherein the gas is selected from one of carbon dioxide (CO2) and nitrogen (N2).

8. The method of claim 1 , wherein the single-phase solution does not comprise a chemical-reaction foaming agent.

9. The method of claim 1 , wherein the single-phase solution comprises a cross-linking agent.

10. The method of claim 1 , further comprising heating the mold above an ambient temperature prior to injecting the single-phase solution.

11. The method of claim 1 , wherein the mold comprises a pressure regulator that maintains at least the mold pressure as the single-phase solution is injected into the mold cavity and wherein the mold cavity remains a constant volume.

12. The method of claim 1 , further comprising filling the mold cavity at least 80% by mold-cavity volume with the single-phase solution.

13. The method of claim 12 , wherein the single-phase solution is a homogenous mixture.

14. The method of claim 1 , further comprising heating the single-phase solid article to form a two-phase mixture.

15. The method of claim 14 , wherein heating the single-phase solid article to form a two-phase mixture is performed in a second mold.

16. The method of claim 15 , wherein the second mold is pressurized above atmospheric pressure to a second mold pressure prior to the single-phase solid article being formed into the two-phase mixture.

17. The method of claim 1 , where cross-linking of the polymer composition occurs prior to a foaming of the polymer composition.

18. A method of molding a single-phase solution, the method comprising:
pressurizing a mold cavity of a mold above atmospheric pressure to a mold pressure, wherein the mold pressure is at least a pressure to maintain the single-phase solution as a homogeneous mixture;
while maintaining the mold cavity at least at the mold pressure, filling the mold cavity with the single-phase solution; and
cooling the single-phase solution below the glass transition temperature to form a single-phase solid article in the mold cavity.

19. A method of molding a single-phase polymer and gas solution, the method comprising:
mixing a polymer composition above a glass transition temperature of the polymer composition with a gas above atmospheric pressure to form the single-phase solution;
pressurizing a first mold cavity of a mold above atmospheric pressure to a mold pressure, wherein the mold pressure is at least a pressure to maintain the single-phase solution as a homogeneous solution;
while maintaining the first mold cavity at least at the mold pressure, injecting the single-phase solution into the first mold cavity;
cooling the single-phase solution below the glass transition temperature to form a single-phase solid article in the first mold cavity; and
depressurizing the first mold cavity below the molding pressure.

20. The method of claim 19 further comprising:
transferring the single-phase solid article to a second mold having a second mold cavity; and
heating the single-phase solid article within the second mold cavity to convert the single-phase solid article to a foamed article.

21. The method of claim 20 , wherein the second mold cavity has a larger volume than the first mold cavity.

Assignees

• Nike Inc

Inventors

• Darland Jeffrey E
• Mace Ryan Alvin

Classifications

• C08J2375/04

  Polyurethanes · CPC title

• C08J2323/08

  Copolymers of ethene (C08J2323/16 takes precedence) · CPC title

• C08J2203/06

  CO2, N2 or noble gases · CPC title

• C08J9/122

  Hydrogen, oxygen, CO2, nitrogen or noble gases · CPC title

• B29L2031/50

  Footwear, e.g. shoes or parts thereof · CPC title