We all know that there are many kinds of plastic bottles, and different materials have different characteristics. Let's compare PET plastic bottles and PP plastic bottles.
Polypropylene (PP) application areas: microwave tableware, basins, plastic barrels, thermos shells, woven bags, etc.
Features: High chemical stability, good hygiene performance, and 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 leading position in China's beverage packaging industry should be PET plastic bottles. So far, no better packaging material has been found to replace PET plastic bottles. PP bottles are mainly made of one-step injection stretch-blow molding and two-step heating stretch-blow molding machines. The PP bottles are transparent, robust and heat-resistant, and the price is lower than that of radical materials. Generally, the PP plastic bottle is mixed with 0.1%-0.4% sorbitol xylene nucleating agent. After blowing, blowing, injection, kneading and other methods, high transparent PP plastic bottles can be produced. PP plastic bottle has good temperature resistance function, sensitive bottle shape description, inferior safety, hygiene and taste persistence of the content, and the price is cheaper than PET, PS, PE and other materials. The use of PP plastic bottles in beverage packaging markets has gradually approached PET bottles. The continuous development of modified resins, anti-reflection agents, and mechanical equipment technology has enabled PP containers to replace glass, PET and PVC containers, and has a broad market prospect.
