Method for producing foamed extrudate

Abstract

The invention relates to a method for producing a foamed extrudate. A method for producing a foamed extrudate comprises an apparatus (10) comprising a main melting apparatus (1) and an auxiliary melting apparatus (2). A first melt (11) is produced in a main melting plant (1) and a second melt (12) is produced from a fusible starting material (3) in an auxiliary melting plant (2). Adding at least one reactive additive (4) to the fusible starting material (3), the at least one reactive additive (4) selected from the group consisting of chemical blowing agents and active nucleating agents being mixed with the second melt (12) in an auxiliary melting device (2) such that an additive-containing second melt (14) is obtained in the auxiliary melting device (2), the additive-containing second melt (14) is added to the first melt (11).

Description

technical field [0001] The present invention relates to a method for producing microcellular foamed plastic or plastic extrudates or functionally equivalent substances or extrudates comprising biopolymers or natural substances such as wood, plants, wood components or vegetable components . Background technique [0002] For simplicity, the starting materials for such extrudates are hereinafter referred to as fusible starting materials. Foamed plastic extrudates are obtained according to known methods by chemical foaming or physical foaming by means of an extrusion process. Melt the plastic and add a blowing agent. In the case of chemical foaming, chemicals are added which decompose under the influence of heat and release gases which then cause a foaming reaction in the plastic melt. In physical foaming, a gas or low-boiling liquid, such as CO, is added to the plastic melt 2 , nitrogen or butane. In addition, chemical substances (so-called active nucleating agents) are ad...

AI Technical Summary

Problems solved by technology

This method has the main disadvantage that the residence time of the chemicals in the extruder is shortened, since the chemicals are not added in the inlet section of the extruder, but only exit the plastic melt near the discharge end of the extruder. body added shortly before

However, after this modification, the second extruder may no longer fulfill the function of the cooling extruder, with the help of which the temperature of the plastic melt is reduced to the ideal temperature for the foaming process

In addition, the use of two extruders is expensive and complex in terms of process technology if a full reaction of the chemicals is required

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