Multi-stage foaming method

Abstract

The invention provides a multi-stage foaming method. The multi-stage foaming method is mainly and technically characterized in that a foaming structure of a polymer raw material is generated through atwo-stage foaming process, wherein in the first-stage foaming process, the polymer raw material and a foaming agent are mixed, under the assistance of feeding devices such as an injection molding machine or an extrusion machine, a mixed material is put into a first mold, foaming is carried out on the mixed material, the mixed material is molded into a foaming blank with a first foaming ratio by the first mold, and then the foaming blank is taken out from the first mold; and in the second-stage foaming process, supercritical fluid is used as a foaming agent, the foaming blank placed in a closed space is foamed for the second time at the preset temperature and under the preset pressure, the foaming blank becomes a foaming object with the second foaming ratio, and the first foaming ratio issmaller than the second foaming ratio.

Description

technical field [0001] The invention relates to polymer processing technology, in particular to a multi-stage foaming method. Background technique [0002] Polymer foam molding technology is to use an appropriate foaming agent in the polymer molding process to make the molded product have a porous structure, so as to achieve changes in physical properties such as reducing density, reducing weight, or improving elasticity. When foaming at medium and low rates, chemical foaming agents are usually used. In contrast, when foaming at medium and high rates, physical foaming agents are usually used. [0003] However, when high-magnification foaming is performed, due to the intense growth of the bubbles, the bubble walls are likely to break, and the small bubbles are combined with each other to form large bubbles, resulting in a decrease in mechanical strength, and even an open foam structure ( opened-cell foam), these technical limitations have led to the expansion of foams with a...

AI Technical Summary

Problems solved by technology

[0003] However, when high-magnification foaming is performed, due to the intense growth of the bubbles, the bubble walls are easily broken, and the small bubbles are combined with each other to form large bubbles, resulting in mechanical The reduction of strength, even the formation of an open foam structure (opened-cell foam), these technical limitations have led to foams that require a closed-cell foam structure (closed-cell foam), such as offshore Floating equipment, tires, shoe soles and other items are not easy to obtain high-quality and stable finished products during high-magnification foam molding processing