Coloring of plastic resin by pearlescent pigment

There are many ways to color thermoplastic resins. Among them, the pearlescent masterbatch is excellent. Although direct coloring is simple, the quality is difficult to guarantee.

 1. Directly color the resin powder

When the powder is colored, it is only necessary to directly add the pigment to the kneader and mix evenly. This type of kneader has two types: drum type and high-speed type. When using a high-speed kneader, add ordinary pigments and other additives to the resin powder and mix evenly. Add pearlescent powder before the end of the mixing. This is because the lamellae structure of pearlescent pigments is easily damaged under the action of high shearing force. , Affect the pearlescent effect. Pearlescent Pigment

2. Directly color the resin pellets

Pearlescent pigments cannot be directly added to the resin pellets, but a liquid coupling agent must be used to fix them on the surface of the resin particles to produce a physical or chemical combination. Such coupling agents include various softeners and refined mineral oils. In addition, the wettability of the interface can be improved by adding emulsifiers or high-boiling solvents. Under normal circumstances, the amount of coupling agent added is 0.2-0.5% of the amount of resin. If the pearlescent pigment is more uniformly dispersed in the resin, 1% of low molecular weight polyethylene powder can be added to the pigment and resin mixture.

With this method, the larger additive amount is 2%. If this amount is exceeded, the excess pigment can only be scattered because there is no space on the resin surface to continue to adsorb.

3. Liquid curing and mixing

Pearlescent pigments can also be pre-mixed with solvents, additives, and organic pigments to make liquid pigments, that is, pearlescent paste. For pulping with organic pigments, the organic pigments should be ground to the specified fineness before mixing with pearlescent pigments. Pearlescent paste should pay attention to the precipitation of pearlescent pigments, use appropriate anti-settling additives, and stir evenly before application to ensure the uniformity of the concentration of pearlescent pigments in the paste. Fluorescent Pigment

4. Coloring with pearlescent masterbatch

The masterbatch method has excellent coloring effect. Ordinary coarse and fine resin powders can be used to prepare color masterbatches. Because pearlescent powder will reduce the melt index after adding, generally use higher melt index, stronger fluidity, and similar polymers with lower molecular weight than the colored resin as pigments. Carrier. There are two methods for the preparation of masterbatch: continuous and intermittent. The general industrial production is continuous production with double screw extruder.