Physical foaming process using foaming press

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.

Dependencies are inferred from the claim text.