What is the reason for the yellowing of pet plastic bottles?

When purchasing PET plastic packaging bottles, some people will find that the product quality of some suppliers is very substandard, and the plastic bottles produced have problems such as "yellow" and "white fog", and they don't know the reason.

Why does it change color? Because PET has a certain degree of hydrophilicity, when the moisture content exceeds the limit, the molecular weight of PET will decrease during processing, causing problems such as discoloration and brittleness. So if recycled materials are used, the proportion of recycled materials should not be too high, and it should be kept dry.

The opaque "white fog" phenomenon occurs because the mold temperature is not well controlled, or the material temperature is not well controlled. The mold should be kept at a low temperature, and the cooling must be fast, so that the cost of the plastic bottle will be transparent. good.

When purchasing PET plastic packaging bottles, in addition to paying attention to the above two problems, Jiaxing Packaging reminds you to also pay attention to whether the thickness of the bottle is uniform, whether the capacity of the bottle is too small, whether there is oil stains, whether the height is uneven, whether the neck is concave, accumulated Materials and other issues.