SAFOAM® can be used in blow-molding. Weight reductions of 5-15% have been achieved. Specific grades depend on the resin(s) used. Blow molding is a two-stage process. A hot tube, or parison, is extruded and then molded by inflation within a mold. The general principles for successful extrusion apply to the parison. A parison can be made in one of two ways:
1. Continuous Extrusion (similar to pipe extrusion) or
2. Intermittent Extrusion
With intermittent extrusion, the melt must be kept under pressure to prevent premature cell formation, resulting in poor or rough surface. As soon as the parison exits the die, expansion and cell formation occur. The die and pin diameter must be adjusted to compensate for expansion. The die diameter must be reduced and the pin diameter increased. Conventional molds are employed (i.e. stationary, reciprocating, or rotary). Since the hot strength of the melt is lower, mold release may be required on the hot knife or wire to obtain a clean cut-off. The blow-pressure may have to be reduced to avoid wall rupture.