Common Problems And Solutions During Casting Film Production (Part Two)

7.Melt Pressure Fluctuation

Melt pressure fluctuations directly affects the film thickness uniformity, the following conditions are easy to cause the melt pressure fluctuation larger:

(1) The raw materials molecular weight distribution is not suitable;

(2) Recycling material too excessive or uneven join;

(3) High main machine speed ,high melt pressure, melt flow in the slip causing the melt pressure decreased, then increased, and then decreased the fluctuation;

(4) Feeding mouth blockage or feeding at high temperature can cause the melt pressure drop.

8.Running Volume At The Time Of Winding

The volume will run while winding , it is a great waste and losses, should be avoided. The following are easy to cause running volume:

(1) The ambient temperature is too high, it will make CPE be more flexible, rigid, easy to slip out, resulting in running volume;

(2) The winding tension is too small and roll too loose;

(3) The winding tension, contact tension is not stable or not match, can check its control measurement of electronic components;

(4) The film electrostatic repulsion is too large,exclusion is large.

9.Uneven Film Roll Surface

The uneven film roll surface will easily to damage film during packaging and transportation, but also has bad impact on film application.

To solve such problems through the following aspects:

(1) The winding tension is too small and roll too loose;

(2) The winding tension, contact tension is not stable or not match, there are fluctuations;

(3) The paper core is not tight enough;

(4) Banana flattening roller improper adjustment;

(5) The corona current strength is too small, because the film surface has a certain viscosity after shocked.

10.Plastic Film Lateral Strength Is Small

Although the film stretching ratio is small, high degree molecular orientation is small, there are still some draft to make vertical orientation, especially to produce thin stretch film (≧0.030mm).

The transverse intensity is small, mainly by the following factors:

(1) Extrusion speed, traction too fast to make big orientation;

(2) The die lip gap is large, thin film pulled by extruded thick film extrusion to cause big orientation, the gap should be less than 20 times film thickness;

(3) The cooling temperature is too low.

11.Stretch Film With Stripes

If the stretch film has herringbone stripes, reasons as followed:

(1) Air knife pressure is too high;

(2) The quench cooling roll cooling is not uniform, need to clean the dirt inside cooling roller;

If the stretch film has straight stripe, the reasons are:

(1) The die lip injury, need to repair;

(2) Die head has impurities , need to clean.

12.Stretch Film Crease

Stretch Film Crease is mainly caused by the following reasons:

(1) Film tension is too small, the film is too loose, wrinkled by the traction ;

(2) The tension is too big to make stretch film be crease;

(3) The balance roller is too large, causing the film oblique, easily crushed;

(4) The stretch film lateral thickness uniformity is poor.

13.Big Film Shrinkage

Due to the film crystallization, cooling, internal stress and other factors, the deposited film has certain shrinkage. Such as shrinkage, reasons can analysis from the following aspects:

(1) Raw material melt index is too large;

(2) High density of raw material and high crystallinity;

(3) The processing temperature is high, the winding tension is too large;

(4) Cooling temperature is high,quenching effect is poor;