1. Crystal Structure Selection
Rutile type: Features dense crystal arrangement, high stability, excellent hiding power and weather resistance. It can effectively block UV erosion and is preferred for outdoor rubber products such as automobile tire sidewalls, to delay aging, discoloration and surface失光 (loss of gloss).
Anatase type: Has a relatively loose crystal structure, low density and strong photochemical activity. It is mostly used in ordinary indoor rubber products with general weather resistance requirements.
2. Mechanical Property Adaptability
Tensile strength: Moderate addition of titanium dioxide can form a complete filler-rubber network structure. When the filling amount is 10php, the tensile strength of natural rubber composites can be increased by about 127% compared with the unfilled system.
Hardness and modulus: Titanium dioxide can significantly improve the hardness and compressive modulus of rubber. Nano-sized (such as 29nm) titanium dioxide particles have more significant enhancement effect.
3. Weather Resistance Performance
Rutile titanium dioxide has excellent UV absorption and scattering capabilities, which can inhibit the photo-oxidation reaction of rubber molecular chains, greatly extend the service life of products in harsh environments, and is suitable for outdoor scenarios such as building sealants and outdoor cable sheaths.
4. Dispersion and Interface Compatibility
Untreated titanium dioxide is hydrophilic, which has poor compatibility with hydrophobic rubber matrices and is prone to uneven dispersion.
Industrial surface modification treatments such as silane and stearic acid are required to make it lipophilic, improve the interfacial bonding force with rubber, and ensure the uniformity of processing performance and finished products.
5. Coloring and Appearance Performance
As a high-efficiency white pigment, it requires high whiteness and strong hiding power, which can avoid color difference and speckle defects in white/light-colored rubber products such as medical rubber gloves and light-colored shoe soles.
Its stable coloring strength ensures no discoloration or cracking of the product under sunlight exposure, and has good acid and alkali resistance.
6. Key Quality Index Requirements
Purity: The content of TiO₂ is usually required to be ≥92%~98%, and the impurity content is low, which will not interfere with the rubber vulcanization process.
Particle size distribution: Narrow particle size distribution is conducive to uniform dispersion and stable mechanical properties.
Chemical stability: It is insoluble in water and weak inorganic acids, and does not undergo chemical reactions with rubber matrix components.