The color unevenness is that the color of the product surface is different, and it can appear near and far from the material, and occasionally in the sharp-edged material flow area.

Reason:
1. Color unevenness is caused by uneven pigment distribution, especially when color is added by color masterbatch, toner, or liquid colorant. At temperatures below the recommended processing temperature, the masterbatch or pigment cannot be completely homogenized. In general, when using a color masterbatch, the compatibility of the pigment and its dissolving liquid with the resin in terms of chemical and physical properties should be ensured.
2. When the molding temperature is too high, or the residual time of the barrel is too long, it is also easy to cause thermal degradation of pigments or plastics, resulting in uneven color.

3. When the material is plasticized or homogenized at the correct temperature, if the injection is too fast when passing through the cross section of the material head, frictional heat may be generated to cause pigment degradation and color change.

Solutions:
1. The materials are not uniformly mixed, reduce the screw speed; 
2. Increase the barrel temperature and increase the screw back pressure
3.  The screw back pressure is too low, increase the screw back pressure
4.  The screw speed is too high, reduce the screw speed