Manufacturing Process of Insolite Expanded Polystyrene

Styropor is converted into blocks and moulded parts in three stages: Pre-expansion, Intermediate Ageing and Moulding.

Pre-expansion

The raw material is heated to about 80° C - 110°C in special foaming units using steam. During this process, the apparent density of the material drops from about 630 Kg/M3 (39 pcf) to about 10 Kg/M3 (0.625 pcf) depending of the temperature and residence time. To make packages and other kinds of mouldings, Styropor is normally re-expanded to 18 - 30 Kg/M3 (1.12 -1.87 pcf).

Prefoaming converts the compact Styropor beads into foam based with small closed cells.

Intermediate Ageing

As the freshly foamed particles cool down, blowing agent and steam tend to condense inside the cells producing a vacuum which has to be equalized by air diffusing into the cells. This imparts greater mechanical stability to the beads, as well as extra foaming power. This process takes place during intermediate ageing in ventilated silos. At the same time, it gives the beads an opportunity to dry.

Moulding

The cavity of the foaming mould, which is usually in two parts, is now filled pneumatically wit the prefoamed material. The mould walls are equipped with the steam chamber. Foam moulding is accomplished by the use of steam to supply the necessary energy.

A surge of steam causes the beads to soften again and expand. The expansion pressure compresses the beads and at the same time forces them against the mould wall so that they fuse together.

The resultant part is the cooled by spraying water on to the mould and by applying a vacuum. When it has cooled down sufficiently, the mould part can be taken from the mould.

This technique can be used to make large blocks, boards and mouldings of almost any shape or size.