Foam extrusion deep interpretation

Date:2022-4-01 Author:

The technology of foaming plastic has a long history. The earliest is the early 20’s of bakelite foam, with similar manufacturing foam rubber method; In the 1930s, rigid polyurethane foam and polystyrene foam appeared; In the 1940s there were polyethylene, polyvinyl chloride, epoxy resin, phenolic foam; In the 1950s, there were expandable polystyrene foam and soft polyurethane foam. Almost all plastics, both thermoplastic and thermosetting, can be foamed. The industrial preparation methods are: foam extrusion, injection foaming, molding foaming, calendering foaming, powder foaming and spraying foaming WPC foam board making machine and so on.

Foam extrusion is the process of producing foamed material by extrusion. The foaming agent and resin are mixed into the extruder, the material is fused and plasticized, and the foaming agent decomposition temperature is reached at the same time. However, due to the screw back pressure and the closed state of the head, the foaming agent can not be formed in the barrel, and the material reaches the formalizer to form the material of the crust surface layer and the foaming core layer.

foam extrusion

Processing of the foam extrusion

Foam extrusion forming technology is one of the main methods for processing foam plastic products, which can carry out continuous production, suitable for a wide range of varieties, can prepare plate, pipe, bar, special-shaped material, diaphragm, cable insulation layer and other foam products.

The main equipment of extrusion foam molding is extrusion machine, auxiliary equipment is generally composed of five parts, such as head, cooling and shaping, traction, cutting, winding or stacking. There are three main processes: mixing, extrusion, foaming and cooling.

The basic principle of extrusion foam molding is similar to ordinary extrusion molding, in the extrusion process plastic and foaming agent and other additives in the extrusion plastic tube to complete plasticizing, mixing, foaming agent decomposition, or foaming agent vaporization, or inert gas pressure injection (mechanical foaming method), And the pressure of the extrusion machine head should be large enough to prevent foaming material from foaming in advance near the extrusion mouth die, foaming material into the mouth die is released to foam molding, the formed foaming products continue to cool and finalize the molding to complete the cooling and final deformation of the products.

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