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Operation instructions of pearlescent pigments in plastics

Pearlescent pigments can be used for transparent and translucent plastic resins. When adding pearlescent pigments will bring a charming color visual effect. It can be widely used in cosmetic containers, various packaging, toys, decorative materials, various films and other plastic products.

Finished sample Finished sample

Operation instructions of pearlescent pigments in plastics:

1.The plastic resin transparency need to be better  

2. Pearlescent pigments mix up with pigments with good transparency

3. Minimize the damage to the pearlescent pigment flakes during processing;

4. The pearlescent powder is fully dispersed and the pigment flakes are oriented parallel to the plastic surface.

In addition to the above conditions, the characteristics and processing methods of the plastic resin will also affect the gloss performance of the final product.

The amount of pearlescent powder in plastics is generally 0.5%-2%, and the amount of film or thin-walled products should be correspondingly larger, generally 4%-5%. There are many methods for coloring plastic resins with pearlescent pigments . Among them, pearl masterbatch is the best. Although direct coloring is simple, the quality is difficult to guarantee.

YT5355 YT5303

YT3426 YT3427

 Fusion steps of pearl powder and plastic:

1.Directly colouring the resin powder

When colouring the powder, just add the pigment directly to the kneader to mix evenly.This type of kneader can be rotary type or high-speed type.When using high-speed kneading machine, ordinary pigments and other additives should be added to the resin powder to mix well, and pearlescent powder should be added at the end of mixing.This is because the high shear force will destroy the pearlite pigment flake crystal structure, affecting the pearlite effect.

2.Directly colouring of resin particles

Pearlescent pigment cannot be directly added to the resin particles. Liquid coupling agent must be used to fix it on the surface of the resin particles to generate physical or chemical binding.In addition, emulsifier or high boiling solvent can be added to improve the wetting performance of the interface.In general, the amount of coupling agent is 0.2-0.5% of the resin dosage.A low molecular weight polyethylene powder of 1% can be added to the mixture of pigment and resin for better dispersion of pearlescent pigment in the resin.The maximum additive amount for coloring by this method 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 mixing

Pearlescent pigments can also be pre-mixed with solvents, additives, and organic pigments to make liquid pigments, that is, pearlescent paste.If pulping is made with organic pigment, grind the organic pigment to the specified fineness before mixing with the pearlescent pigment.Pearlescent paste should pay attention to the precipitation of pearlescent pigments. It is best to use suitable anti-settling additives.The application of pearlite paste should be mixed evenly to prevent the precipitation of pearlite pigment, so as to ensure the consistency of the concentration of pearlite pigment in the pearlite paste.

4.Pearlescent masterbatch coloring

Preparation of pearlescent masterbatch and the use of pearlescent pigment for the thermoplastic resin coloring, masterbatch method is the best effect.Common coarse and fine resin powder can be used to prepare color masterbatch, but it is better to first use high melting index, good fluidity, molecular weight double coated with low resin polymer as the carrier of pigment, color masterbatch preparation has two methods: continuous and gap: the general industrial production using twin-screw extruder for continuous production.

Precautions for the preparation of pearlescent masterbatch:

1.In the mixing process, the pearlescent pigment should avoid the effect of high shear for a long time, so as to avoid damaging the flake crystal structure of pearlescent pigment and affecting the pearlescent effect of the product.

2. Increase the back pressure to improve the mixing effect of the screw and fully disperse the pearlescent pigment;

3. Increase the temperature within the possible range, reduce the viscosity of the melt, and reduce the structural damage to the pearlescent pigment;

4. The smoothness of the mold, the design of the mold gate and the adjustment of the construction are also very important, which will cause the arrangement of the pearlescent pigments to be disordered and affect the pearlescent color of the product.


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