PET is a hygroscopic material, if the moisture content is too high, will produce at a high temperature hydrolysis process, the PET molecular chains and thermal decomposition of acetaldehyde, reduce physical and mechanical properties, the crystallization rate of speed, when the Preform Injection, will Preform partially crystalline bleaching, affecting the quality of the product.
PET is a polymer, the most important feature is its molecular weight, molecular weight is the number of uniform molecular PET molecular chains, the number of molecules of longer chain link, the better the physical properties of PET. PET is a crystalline resin, a specific gravity of about 1.4, a melting point of 245 ℃, the molding temperature between about 290 ~ 315 ℃. Usually used in the manufacture of PET plastic container grain, must pay attention to the following features: (1) molecular weight (2) acetaldehyde content (3) the content of diethylene glycol (4) a carboxyl group (5) the percentage of total polymer ( 6) Melting point (7) a glass transition point (8) the degree of crystallinity. Polyethylene terephthalate (of PET) , having the features: (1) excellent in gas barrier properties (2) pressure resistance, creep resistance (3) Impact resistance (4) transparency, surface gloss (5) itself is odorless and Paul fragrance security (6) on food hygiene, and beautiful, easy molding, has been widely used in food containers. Here are some notes for the PET preform injection molding process, for all my friend, much know-how experience, much near to the perfect production. The final result is that the bad quality &bad production of PET preform in the customer factory, which will waste the money &energy &time of all. And in order to reduce the sell cost, many manufacturers also present the general purpose injection molding machine with C type of screw &big shot weight, while they obviously ignored to bring the important notes to the customer before they make a decision focus on the PET PREFORM PRODUCTION. Many friends would like to adopt the general purpose injection molding machie to produce the PET preform.
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