Single-phase solution molding

Patent metadata

Field	Value
Publication number	US-11911936-B2
Application number	US-202017107404-A
Country	US
Kind code	B2
Filing date	Nov 30, 2020
Priority date	May 31, 2017
Publication date	Feb 27, 2024
Grant date	Feb 27, 2024

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 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 footwear component using a single-phase solution, the method comprising:
pressurizing a mold cavity of a footwear component mold above atmospheric pressure to a mold pressure, wherein the mold pressure is at least a pressure to maintain a single-phase solution as a single phase, wherein the single-phase solution is comprised of a polymer composition and a gas;
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 polymer composition below a glass transition temperature of the polymer composition to form the footwear component,
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,
wherein the gas is selected from one of carbon dioxide (CO 2 ) and nitrogen (N 2 ).

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

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

4. The method of claim 3 , wherein forming the single-phase solution comprises dissolving the gas with the polymer composition while the gas is in a supercritical fluid state.

5. The method of claim 3 , 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 single-phase solution does not comprise a chemical-reaction foaming agent.

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

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

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

10. The method of claim 9 , wherein the single-phase solution is a homogenous mixture.

11. The method of claim 1 , further comprising depressurizing the mold cavity.

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

13. A method of molding a footwear component using 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 a 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;
depressurizing the first mold cavity below the molding pressure; and
cooling the polymer composition below the glass transition temperature to form an article in the first mold cavity,
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.

14. The method of claim 13 , wherein the polymer composition is comprised of a polymer selected from one of polyurethane and ethylene-vinyl acetate.

15. The method of claim 14 , wherein the gas is selected from one of carbon dioxide (CO 2 ) and nitrogen (N 2 ).

16. The method of claim 15 , wherein the glass transition temperature is at least 175 degrees Celsius.

17. A method of molding a footwear component using a single-phase solution, the method comprising:
pressurizing a mold cavity of a footwear component mold above atmospheric pressure to a mold pressure, wherein the mold pressure is at least a pressure to maintain a single-phase solution as a single phase, wherein the single-phase solution is comprised of a polymer composition and a gas;
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 polymer composition below a glass transition temperature of the polymer composition to form the footwear component,
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,
wherein the polymer composition is comprised of a polymer selected from one of polyurethane and ethylene-vinyl acetate.

Assignees

• Nike Inc

Inventors

• Darland Jeffrey E
• Mace Ryan Alvin

Classifications

• B29C44/0415 Primary

  by regulating the pressure of the material during or after filling of the mould, e.g. by local venting · CPC title

• B29C44/105 Primary

  the counterpressure being exerted by a fluid · CPC title

• B29C44/3453

  Feeding the blowing agent to solid plastic material · CPC title

• B29C44/348

  by regulating the temperature and/or the pressure, e.g. suppression of foaming until the pressure is rapidly decreased · CPC title

• B29C44/08

  using several expanding {or moulding} steps · CPC title