Microcellular foaming injection molding technology capable of realizing high foaming ratio and preventing surface from having foam marks

Abstract

The invention discloses a microcellular foaming injection molding technology capable of realizing the high foaming ratio and preventing a surface from having foam marks. The technology comprises steps as follows: polymer melt and a foaming agent are mixed, a preformed blank is molded and transferred, heating and foaming are performed, and a final product is obtained after cooling. The preformed blank and the final product are molded in two mold cavities with different volumes. High cavity pressure, high injection pressure and high holding pressure are adopted, so that the preformed blank is prevented from foaming in the molding process. After the cooled preformed blank is fixed in a final product molding cavity, molds are closed and heated, and the inside of the preformed blank foams. Through the high-pressure injection technology of the preformed blank, the surface of the product can be free of defects such as crazing, spiral stripes, foam pits and the like, and the volume difference between the preformed blank and the final product provides space for growth of a bubble-shaped nucleus. The technology can be used for producing microcellular foaming injection molded products with good surface quality and dense inside cells.

Description

technical field [0001] The invention relates to a microcellular foaming injection molding process, which is used for producing injection molded parts with high internal foaming ratio and no bubble marks on the surface. Background technique [0002] Microcellular foamed plastics are defined as cells with a cell size of 1 to 10 μm and a cell density of 10 9 ~10 10 piece / cm 3 , A polymer material with a closed cell structure. The main design idea of ​​the material is: when the size of the cells in the plastic is smaller than the cracks inside the material, the existence of the cells will passivate the original crack tips of the material, which is beneficial to prevent the cracks from expanding under stress, so that the material The mechanical properties are improved. Since the advent of microcellular foam injection molding technology for more than 30 years, although it has received widespread attention in the fields of automobiles, home appliances, aerospace, and biomedicin...

AI Technical Summary

Problems solved by technology

This method will also divide the forming process of the product into two parts, and accelerate the foaming agent into the polymer system through screw agitation, but this technology is only applicable to blow-molded hollow container plastic parts

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