The application and difference of PP material and PET material
Polypropylene (PP) applications: microwave tableware, basins, plastic barrels, thermos shells, woven bags, etc. Features: High chemical stability, good hygiene performance, high heat resistance. Microwave tableware can be made of plastic products marked with PP. Toxicity: non-toxic and harmless to humans. The polymer can have three three-dimensional structures: isotactic, syndiotactic, and atactic polypropylene. The former two can be crystallized while the latter cannot. Commercially available polypropylene products basically have an isotactic structure, with a melting point of 164 to 170 degrees Celsius, a density of 0.935 g/cm3 in the crystalline part, and 0.851 g/cm3 in the non-clean part. The biggest disadvantage of PP is that it is easy to oxidize and age. Now it is overcome by adding antioxidants and ultraviolet light absorbers.
Polyester (PET) applications: plastic beverage bottles, medicine bottles, cosmetic bottles, oil bottles and various bottle caps and thermal insulation caps. Features: Good transparency, not easy to break, good chemical stability, suitable for a variety of liquid or solid medicine packaging. It has good shielding properties to ultraviolet rays. Toxicity: non-toxic.
PET plastic bottles are the mainstream of beverage packaging. The dominant position in China’s beverage packaging industry should be PET plastic bottles. So far, no better or better packaging material has been found to replace PET plastic bottles. PP bottles are mainly molded by one-step injection stretch-blow molding and two-step heating stretch-blow molding machines. The PP bottles have the advantages of transparency, robustness, heat resistance, and low cost.
PP plastic bottles have better high temperature resistance, sensitive bottle shape description, inferior safety, hygiene and taste persistence of the contents. The price is cheaper than PET, PS, PE and other materials. The scale of use of PP plastic bottles in the beverage packaging market has gradually approached PET bottles. The continuous development of modified resins, anti-reflection agents, and mechanical equipment skills have enabled PP containers to replace glass, PET and PVC containers.