Page 368 - Handbook of Plastics Technologies

PLASTICS ADDITIVES

5.48 CHAPTER 5

FIGURE 5.11 Organic colorants.

carbon black 13 percent, organic pigments 5 percent, and dyes 2 percent. But recent trends
have probably favored the replacement of inorganic by organic colorants.
Prices for inorganic colorants are mostly $1 to $3 per pound, and $3 to $30 for organic
colorants.

5.8.6 Compounding Techniques
5.8.6.1 Powdered Color Pigments. The primary particles are individual crystals. These
are firmly bonded into tight clumps called aggregates. These are further bonded into loose
clumps called agglomerates. It takes skill and energy to disperse these into molten plas-
tics, and this is best done by experts. The average compounder/processor may waste much
time looking for the optimum technique.
5.8.6.2 Colored Compound. Processors can buy the plastic compound already precol-
ored. This is commonly done with specialty plastics. It is expensive and leaves the proces-
sor with inventory problems.

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