Production Process Quality Control of cast film die
In the premise of quality assurance of raw materials, cast film die production process is the key to control product quality, including temperature, production line speed, thickness control, stratified shunt control, surface treatment.
(1) temperature control. Melt extrusion must choose the appropriate temperature, the plastic pellets completely extruded, or the film will appear on the crystal point stripes and other defects, due to the plasticizing temperature of various materials are different, so a variety of materials should choose different Extrusion temperature. However, it should be noted that when processing temperature is too high, PA, EVOH or PVDC will degrade, making the product turn yellow.
Because the melt temperature and the viscosity of the melt is closely related to the multi-layer coextrusion die, the melt temperature can be properly adjusted so that the viscosity of various materials close to, easy to stratify, the stratification of the layers more evenly.
Casting slab temperature of the physical and mechanical properties of the film, optical properties, sealing properties have an impact. The higher the temperature, the better the physical and mechanical properties, the worse the optical and heat sealing properties; the lower the temperature, the worse the physical and mechanical properties, the better the optical and heat sealing properties. These should attract attention.
(2) hierarchical shunt control. Multi-layer co-extruded cast film die stratified by the splitter to achieve a variety of melt through the splitter will be arranged into the desired structure, so that balanced outflow, by adjusting the flow of each layer of the splitter opening and degree of the layers Flow rate is basically the same, to ensure that the production of co-extruded film with good delamination, casting film machine, if the adjustment is not appropriate, when the flow velocity is relatively large, may produce eddy currents, seriously affecting the delamination.
(3) production line speed, thickness control. According to weighing the extrusion speed and production speed of each layer, by controlling the extrusion speed and production speed to reach the thickness of each layer; cross-section thickness control by the on-line thickness monitoring system directly fed back to the die, cpp cast film die, Adjust the lip opening degree, pvc cast film, the film thickness formation.
(4) Surface treatment. According to the needs of use, multi-layer co-extruded cast film die,but also with pure aluminum, polyester film composite, cast film, the surface layer required for corona treatment, the surface tension of 38nN / m or more to ensure the firmness of the composite product .