Production Process of Pearlescent Pigments
Pearlescent pigments are known for their pearl-like luster. They are widely used in various industries such as cosmetics, automotive coatings, plastics, inks, and more. The production of these pigments involves a series of meticulous steps, ensuring the final product meets the desired quality standards.
- Raw Material Preparation
The production starts with the selection of high-quality raw materials. Key ingredients include mica, synthetic mica, metal oxides, and solvents.
- Raw Material Processing
The raw material such as mica undergoes primary crushing. Then it undergoes secondary crushing. The process is followed by screening to classify particle sizes and remove impurities. This ensures the uniformity and purity of the raw materials.
3. Synthesis of Pearlescent Pigments
In a typical process, a titanium salt (such as TiCl4) is added to a mica suspension. Under acidic conditions and heat, the titanium salt hydrolyzes and deposits as TiO2 onto the mica flakes. The reaction can be represented as:
TiCl4 + 4H2O → H4TiO4 + HCl
H4TiO4 → TiO2 + 2H2O
The resulting TiO2 film, after washing, filtering, drying, and calcining, forms the basis of the pearlescent effect.
4. Dehydration and Drying
The precipitate undergoes dehydration, often through centrifuging or vacuum dehydration, followed by drying using hot air or freeze-drying methods.
5. Packaging and Storage
The final pigment is packaged using suitable materials and methods, ensuring it remains stable during storage. Proper storage conditions and time limits are specified to maintain product quality.
6. Quality Control and Testing
Throughout the production process, rigorous quality control measures are implemented. These measures include testing for particle size distribution and glossiness. They also check chemical composition and heavy metal content. This ensures the pigments meet the necessary specifications.