While processing with plastic polymer with masterbatch (or pigment powder) injection parts, some companies may meet with problems of color aberration or pigment figure on final products. In most cases, we will try to increase back pressure to lengthen melting time, so that to improve for color dispersion or to change screw with mixing section to improve mixing. But another better way is to use directly static mixer nozzle, which is more benefit in dropping back pressure and shorten cycle time, and with much better improvement in homogenize melting polymer and avoid pigment patch. 

-      Cause of pigment patch

Standard injection molding machine are not designed and not suitable for pigment added polymers, so usually modified plastics with mixed colors are been used, which can avoid the problem. However due to plastic injection cost increase, some companies try to lower down cost by adding pigment to polymers, which material cost is much lower. But additional added pigment and masterbatch are hard to disperse and cause pigment patch.

-      Benefit of static mixer nozzle

By using static mixer nozzle, the exponential mixing can evenly scatter the polymer and masterbatch, which to enhance color mixing, and avoid pigment patch, meanwhile screw will need less back pressure, charging time will become shorter.

-      Pressure loss of static mixer

Though static mixer can benefit in color mixing and injection efficiency, but some certain injection pressure loss may unavoidable, and pressure loss varier per different polymers, for high viscosity polymers, the pressure drop is comparingly less, which may range from 10-50bar, however for low viscosity polymers, pressure drops is comparingly higher, which may range from 20-100bars.