Method for producing extrusion molding polystyrene polyfoam for heat insulation by supercritical carbon dioxide foaming

Abstract

The invention relates to a method for producing extrusion molding polystyrene polyfoam for heat insulation by supercritical carbon dioxide foaming as well as a gradually-changed mixing-type screw rod and a backpressure mixing-type screw rod thereof. The method comprises the following steps: uniformly mixing a nucleating agent, a hole opening agent, an additive and polystyrene; controlling the pressure between 16 Mpa and 18 Mpa and the temperature between 180 DEG C-200 DEG C of a first extruder; controlling the pressure between 16 Mpa and 10 Mpa and the temperature between 70 DEG C-100 DEG C of a second extruder; controlling the pressure between 7 Mpa and 8 Mpa and the temperature between 50 DEG C-45 DEG C of a die head; and adding supercritical state carbon dioxide with the pressure between 16 Mpa and 18 Mpa and the temperature between 50 DEG C-60 DEG C. The invention realizes environmental-friendly foaming, eliminates the damage to an atmosphere ozone layer by Freon, reduces environmental pollution and also greatly reduces the production cost, and the cost of products per ton is reduced by 4,000 RMB or so; the quality of the extrusion molding polystyrene polyfoam is greatly improved, the flexibitity and the compressive strength of a plate are respectively improved by 20 percent, and the fire resistance is stable.

Description

1. Technical field [0001] The invention relates to the technical field of extruded polystyrene foam for heat insulation, and relates to a production method of extruded polystyrene foam for supercritical carbon dioxide foaming and heat insulation, as well as a gradual mixing screw and a back pressure mixing screw. 2. Background technology [0002] The usual extruded polystyrene foam production process for heat insulation uses freon as a blowing agent. Because freon damages the atmospheric ozone layer, according to the International Montreal Convention, our country also prohibits its use. At present, the extruded polystyrene foam board industry for heat insulation temporarily uses fluorine-containing substitutes R22 and 142B (R22 and 142B are both fluorine-containing compounds, and are currently used to replace Freon for heat insulation extrusion due to their small damage to the ozone layer. Styrofoam foam blowing agent) transition, will be completely banned by 2030. Therefor...

AI Technical Summary

Problems solved by technology

[0007] The present invention also provides a gradual mixing screw, which overcomes the deficiencies of the above-mentioned prior art, and can effectively solve the problem that the existing pusher screw cannot make the product reach acceptable quality when it is used for carbon dioxide foaming...

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