A microcellular foaming injection molding process and mold with high surface gloss and high bubble density

Abstract

The invention discloses a microcellular foaming injection molding technology capable of realizing high surface glossiness and high bubble density as well as a mold. The technology comprises steps as follows: a physical foaming agent or a chemical foaming agent is evenly mixed with polymer melt in a high-pressure environment by the aid of a microcellular foaming injection molding machine; the temperature of a mold is increased, high-pressure gas is introduced into a cavity of the mold, the polymer melt smaller than the total volume of the cavity of the mold is injected into the cavity of the mold, and foaming space is reserved; the high-temperature state of the wall surface of the cavity of the mold is kept, gas channels located on a moving mold side wall surface of the cavity of the mold and a parting surface of the mold are opened in a matched manner, a gas is controlled to enter and leave the cavity of the mold, and the polymer melt is controlled to flow, so that the reserved foaming space is transferred to the moving mold side of the cavity of the mold; the mold is cooled, when the temperature of the melt is decreased to the foaming temperature, all gas channels of the mold are opened, gas inside the reserved space is exhausted, and a polymer foams and fills rest space of the cavity of the moving mold. The technology can prevent dynamic foaming and promote static foaming and can be used for producing plastic products with the high surface glossiness and the high inside bubble density.

Description

technical field [0001] The invention relates to a process method and a mold structure for controlling the foaming process of polymers in the cavity of an injection mold, in particular to a control method for avoiding dynamic foaming and promoting static foaming, which is used to produce high-gloss surfaces and internal bubbles. Dense plastic product. Background technique [0002] In the early 1980s, Professor Suh in the United States proposed and developed a microcellular foamed plastic, that is, a polymer microcellular foamed material prepared with a thermoplastic as a matrix and a supercritical fluid as a foaming agent. Compared with ordinary polymer materials, its density can be reduced by 5% to 95%, its impact strength can be increased by 5 times, its toughness can be increased by 5 times, its stiffness can be increased by 3 to 5 times, and its fatigue life can be extended by 5 times. The rate has also dropped significantly, and the application fields of microcellular f...

AI Technical Summary

Problems solved by technology

However, this method does not mention how to ensure the surface quality of foamed products, and this method is not suitable for products with structures such as thin-walled or ribbed columns.

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