Brief analysis of PVC color masterbatch formula

(1) Carrier

The carrier resin is a substance that carries a pigment and uniformly disperses the pigment under the action of a dispersant and a processing modifier. Some imported PVC masterbatches use special polyesters as carriers. Generally, a liquid suspension polyvinyl chloride SG-6 or SG-7 can be used as a carrier.

(2) Plasticizer

Polar polyvinyl chloride has high attraction between molecules, high viscosity, and is difficult to melt and flow. Therefore, it is necessary to add a plasticizer to reduce the inter-molecular force of the resin, thereby lowering the melt flow temperature and melt viscosity of the polyvinyl chloride resin. Considering the softness and hardness required for the masterbatch, one or several different plasticizers may be added as needed. Plasticizers generally use dioctyl phthalate (DOP) as the main plasticizer, and epoxy compounds with low volatility and stabilizer function are used as auxiliary plasticizers.

(3) Heat stabilizer

Polyvinyl chloride is easily decomposed when heated, and HCl gas is evolved, so a heat stabilizer must be added. Since the masterbatch is prepared by a twin-screw extruder, the thermal stability of the resin system is more demanding.

(4) Processing modifier

As a masterbatch, the ideal fluidity should be that its fluidity is better than that of the original pigment, that is, the viscosity of the masterbatch should be lower than that of the original pigment, so that the coloration can be uniform. The addition of a high concentration of pigment greatly increases the viscosity of the polyvinyl chloride, especially when a carbon black which is difficult to disperse and absorbs a large amount of oil is added, and even if a very high proportion of the plasticizer is added, the viscosity of the system is still high. By selecting a suitable processing modifier, the melt viscosity of the system is effectively reduced, which is more conducive to the dispersion of the pigment, in order to ensure continuous processing stability.

(5) Lubricant

In the polyvinyl chloride resin, the inner and outer lubricants must be added, and the inner and outer balances should be balanced to reduce the maximum torque when the resin is melted, and to ensure the brightness of the appearance of the product.

(6) Pigments

PVC coloring generally uses inorganic and organic pigments. Since the HCl gas generated by the decomposition of PVC during processing tends to disintegrate some acid-resistant colorants at high temperatures, the pigment used in PVC should satisfy:

a, temperature resistance, the processing of the pigment at 160 ~ 220 ° C, the temperature does not decompose;

b, not affected by HCl;

c, good migration resistance;

d, good weather resistance;

e, cheap.