December 4, 2025
To achieve a bright, pure white in plastic products, the selection of titanium dioxide is critical. Blue-tone titanium dioxide produced via the chloride process is preferred due to its fine particle size and uniform molecular weight distribution, which imparts a fresh, clean appearance. Titanium dioxide with larger particles and yellowish undertones will fail to produce the desired brightness regardless of adjustment methods.
When titanium dioxide alone does not provide sufficient whiteness, additives are employed. Minimal additions of blue or violet pigments, or fluorescent whitening agents, can enhance whiteness. The most common and straightforward method involves using phthalocyanine blue to create an optical brightening effect known as "magnetic white." While fluorescent whitening offers the best results, it also carries the highest cost.
For producing deep black plastic products, attention must be paid to carbon black’s optical properties. Under incident light, finer particle carbon black appears bluer, while in transmitted light (for transparent coloring) it may appear brownish or gray. To obtain a rich, glossy black product, low-structure carbon black with small particle size is recommended, as finer particles increase light absorption, reduce reflection, and enhance blackness. Achieving optimal tinting strength requires excellent carbon black dispersion.
Oxidized carbon black, which contains polar groups such as -OH and -COOH, exhibits improved dispersion. The volatile content index in carbon black specifications indicates its oxidation level—higher values correspond to better oxidation and dispersion performance.
