Injection stretch blow molding is a process for manufacturing predominantly hollow bodies with rotational symmetry using polymers.
Phenomenon of Effect pigments and the interesting frost effect
Due to the soft heating during the blow molding process, its elasticity is not very high. Effect pigments are now elastic anyway due to their inorganic composition. The stretches form voids between the stretched polymer and the unstretchable effect pigments. The larger the pigments and the higher the stretching ratio, the more obviously the vacuoles are. Effect pigments can be used at stretching ratios of up to 3:1. In addition, 1-level or 1.5-level processes are more suitable, because the plastic is still in a semi-viscous state.
In general this void effect is broadly used for the so-called frost effect in PET bottles. This frost effect gives the surface an appearance like it comes directly out of the fridge.