Canning and Fish Packaging Technology

Unit 9 - Plastics for Packaging

9.2.6.Polypropylene (PP)
It has higher softening point 140-150^oC than HDPE. It is a good water vapour barrier, a fairly good gas barrier and has good grease or oil resistance. However, it does not perform well at low temperature as it becomes brittle and its impact strength gets lowered. Widely used as bi-axially oriented film (BOPP film) in which the film has been stretched in two directions during manufacture. BOPP film has improved tensile strength but reduced tear resistance. It is widely used for packaging snack foods such as potato crisps and biscuits. Its price is about twice as that of LDPE on weight basis. However, as it can be extruded very thin more number of pouches can be obtained.