The commonly used raw material of film blowing machine is olyolefin,which is a kind of high crystalline polymer.Therefore,the important factor affecting transparency is resin raw materials.Of course,improving the quality of the film blowing machine is also a consideration,but the technology of the film blowing machine itself has little influence on the transparency of the film blowing.Transparency refers to the percentage of the transmitted light intensity whose scattering angle is less than 0.1°in the incident light intensity when the incident light passes through the sample.The higher the transparency of the film,the clearer the remote image through the film.Transparency is related to the crystallinity and surface flatness of the film.The lower the crystallinity,the more amorphous areas,and the smoother the surface,the higher the transparency.
It can be seen that the best way to improve the transparency of the film is to use lower crystallinity and small spherulites.This can reduce the surface tension of the film,thereby reducing the thickness of the film.In addition,adding a certain amount of plasticizer in the film can also improve the transparency of the film.No matter how advanced the film blowing technology is,it can only improve the transparency to a certain extent.
In view of the above,in the case of relatively good raw materials,how to solve the problem of transparency of blown film?First of all,the extrusion temperature of the film blowing machine is too low,and the melt plasticization is not good.This problem can usually be solved by raising the melt temperature.On the other hand,poor cooling after film blowing will also affect transparency.The corresponding mechanism is to increase the cooling air volume.
In terms of returning to raw materials,more water in the resin ball will also affect the transparency of the blown film.This problem is relatively simple.It is only necessary to fully dry the resin ball.However,if the fiber is stripped,special treatment is required,such as coating a transparent protective film on the surface of the resin ball,which can prevent the transparency of the resin ball from decreasing due to excessive moisture.
