How PET bottles are formed

PET bottles are plastic containers made from PET plastic material through one-step or two-step processing. PET plastic of PET bottles is characterized by its light weight, high transparency, and resistance to impact and shattering.

PET of lotion bottle, or polyethylene terephthalate, is commonly referred to as polyester. Its English name is Polyethylene Terephthalate, which is produced by the polymerization reaction (condensation) of two chemical raw materials: terephthalic acid (PTA) and ethylene glycol (EG).

Preforms of PET bottles are injection-molded items. As intermediate semi-finished products for subsequent biaxial stretch blow molding, the neck of the preform is already formed during the injection molding stage, and its size will not change during heating and stretching/blowing. The size, weight, and wall thickness of the preform are factors that we need to pay close attention to when blowing PET bottles.

The diameters of lotion bottle mouth that can pass through include Ф18, Ф20, Ф22, Ф24, Ф28, Ф33, etc. (corresponding to the T dimension of the bottle mouth), and the screw thread specifications are usually divided into: 400, 410, 415 (corresponding to the number of screw thread turns). Generally, we say that 400 is 1 turn of screw thread, 410 is 1.5 turns of screw thread, and 415 is a high position with 2 turns of screw thread.

How PET bottles are formed:

The process that completes the injection, stretching and blowing procedures in one machine is called one-step method. In the one-step method, after the preform is injection molded and cooled, the stretching and blowing lotion bottle action is performed. Its main advantages are energy saving, high productivity, no manual intervention, and reduced pollution.

The two-step method separates injection and stretching and blowing lotion bottle, and performs them in two machines at different times, also known as the injection-stretch-blowing lotion bottle process. In the first step, the preform is injection molded using an injection molding machine. In the second step, the preform at room temperature is reheated and stretched and blown into PET bottles. The advantages of the two-step method are that it can purchase preforms for blow molding. It can reduce investment (in personnel and equipment). The volume of the preform is much smaller than that of the bottle, making it convenient for transportation and storage. Preforms produced in the off-season can be blown into PET bottles in the peak season.

PET bottles are widely used in the cosmetics industry, mainly in the hair care and body care sectors. Bottles for shampoo, body wash, toner, and makeup remover oil are all manufactured through blow molding.