Preform is one of the important factors affecting the P […]
Preform is one of the important factors affecting the PET bottle blow molding process.
When preparing blow-molded bottles, PET chips are first injection-molded into preforms. It requires that the proportion of secondary recycled materials cannot be too high (less than 5%), the number of times of recycling cannot be more than two, and the molecular weight and viscosity cannot be too low (molecular weight 31,000- 50000, intrinsic viscosity 0.78-0.85 cm3 / g). Preforms for injection molding need to be stored for more than 48 hours before they can be used. The preforms that have not been used up after heating must be stored for more than 48 hours before being reheated. Preforms cannot be stored for more than six months.
The quality of preforms depends largely on the quality of PET materials. Materials that are easy to inflate and shape should be selected, and a reasonable preform molding process should be formulated. Experiments have shown that preforms made from PET materials of the same viscosity are easier to blow-mold than domestic materials; while the preforms of the same batch have different production dates, the blow molding process may also be quite different. The quality of the preform determines the difficulty of the blow molding process. The requirements for the preform are purity, transparency, no impurities, no abnormal color, suitable injection point length and surrounding halo.