Coloring of plastic resins with pearlescent pigments

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

1. Direct coloring of resin powder

When coloring powder, just add the pigment directly into the kneader and mix it evenly. This type of kneader has two types: rotary drum type and high-speed type. When using a high-speed kneader, ordinary pigments and other various additives should be added to the resin powder and mixed evenly. AddPearlescent powder, this is becausePearlescent PigmentsThe platelet structure is easily destroyed under high shear force, affecting the pearlescent effect.

2. Direct coloring of resin pellets

Pearlescent pigments cannot be added directly to the resin pellets, but must be fixed to the surface of the resin particles with a liquid coupling agent to produce a physical or chemical bond. Such coupling agents include various softeners and refined mineral oils. In addition, the wetting properties of the interface are improved by adding emulsifiers or high-boiling point solvents. Usually, the amount of coupling agent added is 0.2-0.5% of the resin amount. If the pearlescent pigment needs to be dispersed more evenly in the resin, 1% low molecular weight polyethylene powder can be added to the mixture of pigment and resin.

The maximum amount of coloring added using this method is 2%. If the amount exceeds this, there will be no space on the resin surface for further adsorption, and the excess pigment will just scatter out.

3. Liquid-curing mixing

Pearlescent pigments can also be mixed with solvents, additives, and organic pigments in advance to form liquid pigments, i.e., pearlescent slurry. If slurry is made with organic pigments, the organic pigments should be ground to a specified fineness before mixing with the pearlescent pigments. Pearlescent slurry 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 slurry.Fluorescent Pigments

4. Pearlescent masterbatch coloring

The masterbatch method has an excellent coloring effect. Ordinary coarse and fine resin powders can be used to prepare masterbatches. Since the addition of pearlescent powder will reduce the melt index, similar polymers with higher melt index and stronger fluidity and lower molecular weight than the colored resin are generally used as pigment carriers. There are two methods for preparing masterbatches: continuous and intermittent. Generally, industrial production uses a double screw extruder for continuous production.