Gas-assistant extrusion molding method

Abstract

A gas-assistant extrusion molding method relates to polymer extrusion molding processing, and adopts a gas-assistant extrusion molding control system and a gas-assistant extrusion molding die to allow polymer melt to form a stable gas cushion film between the inner wall of the extrusion die and the extruded melt during the extrusion molding process of polymer melt, and thus the frictional resistance between the die wall surface and the extruded melt is reduced, and the gas-assistant extrusion molding is realized; therefore, the extrusion swelling phenomenon during the extrusion molding process is basically eliminated; the die pressure drop is reduced; and the surface quality problems of 'sharkskin', extrusion rupture phenomenon, and the like are prevented in the extrusion molding process.

Description

technical field [0001] The invention belongs to the field of polymer extrusion molding. A gas-assisted extrusion molding method is used to make a polymer melt form a stable air cushion film layer between the inner wall of an extrusion die and the extrusion melt during the extrusion molding process. The method of reducing viscosity and drag. Background technique [0002] Extrusion molding has become one of the basic molding methods in the polymer processing industry due to its advantages such as many changes, wide uses, high production efficiency, low investment, and continuous production. About 40% of polymer products are formed by extrusion processing. Molding plays a pivotal role in polymer processing. However, the traditional extrusion molding has the following problems: 1) Extrusion swell, extrusion swell refers to the phenomenon that the cross-sectional size of the extruded product is larger than the size of the extrusion die, and the extrusion swell increases the diff...

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Problems solved by technology

However, the traditional extrusion molding has the following problems: 1) Extrusion swell, extrusion swell refers to the phenomenon that the cross-sectional size of the extruded product is larger than the size of the extrusion die, and the extrusion swell increases the difficulty of the design of the extrusion die and affects Product precision

2) The pressure drop of the extrusion die is large. Due to the high viscosity of the polymer material, a large die pressure is required to overcome the resistance of the inner wall of the die to the extrudate during extrusion, resulting in a large pressure drop of the die, so that the extruded product Increased stress, resulting in increased deformation and also increased energy consumption

3) Defects in the surface quality of the extruded product. When the extrusion speed exceeds a certain limit, "shark skin" and extrusion cracks appear on the surface of the extruded product. The appearance of surface quality defects in the extruded product limits the increase in the extrusion speed , affecting production efficiency

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