Polyolefin is a crystalline high polymer. The key to improve the transparency of film blowing machine is to reduce the crystallinity and make the spherulite fine. The main influencing factor is the resin raw material. The film blowing process can only improve the transparency to a certain extent. The cause analysis and treatment methods of the poor transparency of the film are as follows.
(1) The cooling effect is poor, which affects the brightness, so the cooling air should be increased appropriately
(2) If the outlet temperature is low and the melt plasticization is poor, the melt temperature should be increased appropriately
(3) Resin particles contain a lot of water, and the particles should be fully dried
Fine pores are mainly additives, low molecular weight resins and dust in raw materials. During processing, the film blowing machine condenses on the die, and the film is continuously taken away after accumulating a certain amount, so as to form fish eyes on the film. Because it is caused by precipitates in the resin, it cannot be fundamentally eliminated. The main mediation methods in the process are as follows.
(1) Clean the die regularly.
(2) After a certain time, increase the screw speed, increase the melt extrusion pressure and take away the precipitates.