Physical foaming process using foaming press

Patent metadata

Field	Value
Publication number	US-12459171-B2
Application number	US-202017784149-A
Country	US
Kind code	B2
Filing date	Oct 30, 2020
Priority date	Dec 11, 2019
Publication date	Nov 4, 2025
Grant date	Nov 4, 2025

Abstract

The present invention relates to a method preparing a highly functional foam by a physical foaming process (physical blowing agent-based foaming) used to prepare a midsole of a shoe, and relates to a technology that is environmentally friendly because a chemical foaming agent is not used and is capable of preparing a foam with improved physical properties at a low cost by shortening a processing time. To this end, according to the present invention, a physical foaming process of preparing a foam by using a foaming press provided with a cavity includes: an injecting step of injecting a foaming compounding resin into the cavity; a closing step of closing the cavity by using the foaming press; a gas injecting step of injecting gas into the cavity; an atmospheric pressure maintaining step of dissolving the gas in the foaming compounding resin by maintaining the inside of the cavity at a constant pressure; and a foaming step of performing foaming by opening the cavity so that the inside of the cavity is depressurized.

First claim

The invention claimed is:

1 . A physical foaming process of preparing a foam by using a foaming press provided with a cavity, the physical foaming process comprising:
an injecting step of injecting a foaming compounding resin into the cavity; a closing step of closing the cavity by using the foaming press; a gas injecting step of injecting gas into the cavity; an atmospheric pressure maintaining step of dissolving the gas in the foaming compounding resin by maintaining the inside of the cavity at a constant pressure; a rapid-opening and demolding step, simultaneously performed in a single action, of (i) rapidly opening the cavity at a speed sufficient to cause an abrupt pressure drop inside the cavity to perform foaming and (ii) removing the foam molded in the form of a chamber, wherein a temperature inside the cavity is 90 to 180° C.

2 . The physical foaming process of claim 1 , wherein, in the injecting step, the foaming compounding resin is injected to occupy 50 to 100% of the volume of the cavity.

3 . The physical foaming process of claim 1 , wherein, in the closing step, the foaming press closes the cavity with a pressure of 100 to 200 kgf/cm 2 .

4 . The physical foaming process of claim 1 , wherein, in the gas injecting step, the gas is injected into the cavity so that the cavity is pressurized to a set pressure of 5 to 20 MPa.

5 . The physical foaming process of claim 1 , wherein, in the atmospheric pressure maintaining step, the inside of the cavity is maintained at a pressure of 5 to 20 MPa.

6 . The physical foaming process of claim 1 , wherein the atmospheric pressure maintaining step is maintained for 1 to 100 minutes.

7 . The physical foaming process of claim 1 , wherein the gas includes one selected from the group consisting of nitrogen gas, carbon dioxide gas, supercritical carbon dioxide gas, argon gas, and helium gas.

8 . The physical foaming process of claim 1 , wherein the foaming compounding resin is in a solid form.

9 . The physical foaming process of claim 8 , wherein the foaming compounding resin is in a solid form of a sheet or pellet form.

Assignees

• Hanwha Solutions Corp

Inventors

• Bae Seong Soo
• Kang Chul Ee
• Lee Sang Jin
• Lee Jae Hyeok

Classifications

• C08J2331/04

  Homopolymers or copolymers of vinyl acetate · CPC title

• C08J2323/08

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

• C08J2203/08

  Supercritical fluid · CPC title

• C08J2203/06

  CO2, N2 or noble gases · CPC title

• C08J9/0028

  containing nitrogen · CPC title