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PVDC multilayer co-extrusion film production technology

by:LINYANG     2020-03-21
Due to the different methods of film, can be divided into multi-layer co-extrusion blown film and multilayer co-extrusion stretch film, both, compared to stretch film than blown film has more excellent transparency and dimensional stability, degree of thickness control more accurate. Such as sapphire company, it can produce three, five layers symmetric and asymmetric membrane structure, its product structure are as follows: symmetry class, PE/EVA/PVDC/EVA/PE; Not say class, PP/EVA/PVDC/EVA/PE. Practice shows that the success of a total of extrusion products production, depends on three key factors: the choice of polymer, screw, feed block and mold design and the best process conditions. Select material of each layer in the process of co-extrusion must have similar thermal performance ( Melting temperature and melt sticky degree, etc. ) , have bonding effect between layer and layer. With PVDC resin with affinity effect is very little, the most commonly used only EVA. Although PVDC that can tolerate 121 t cooking, and heat resistance of multi-layer co-extrusion, depends on the surface, and the co-extrusion layer and the lowest temperature tolerance in the sort of resin bonding resin. We know that EVA can only be used under 80 ℃, to have it as a bonding layer by the multi-layer co-extrusion film cannot be used for more than 80 ℃ long time use, with PVDC co-extrusion film packing meat can only use pasteurized, cannot be used for 121 ℃ cooking. In PVDC co-extrusion film production, PVDC barrier property decides the co-extrusion the barrier property of the product, 8 - table 8 is asymmetric PP/EVA/PVDC/EVA/PE five layers co-extrusion composite film detection index, membrane oxygen through the quantity of 4. 26 cmvm2, 24 h, ATM, water vapor through the quantity of 1. 79g/m2 . 值班。 PVDC co-extrusion application performance in: (1) for oxygen, water vapor blocking rate is high, used to wrap meat products, frozen products; Drugs, chemicals; Electronics, machinery, military industry products, precision parts, etc. (2) mechanical performance is good, suitable for automatic packaging machine should be used, for aseptic packaging of fresh milk, dairy products. (3) can be microwave heating.
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