The plastics industry is the second largest user of titanium dioxide and the fastest growing field in recent years. Titanium dioxide plastic can not only make use of its high covering power, high achromatic power and other pigment properties, but also improve the heat resistance, light resistance and weather resistance of plastic products, so as to protect plastic products from UV light, so as to improve the mechanical and electrical properties of plastic products.
Most of the titanium dioxide particles used in plastics are fine. The particle size of titanium dioxide used in coatings is usually 0.2 ~ 0.4 μm, while the particle size of titanium dioxide plastic is 0.15 ~ 0.3μM. In this way, a blue background phase can be obtained, which can shield most resins with yellow phase or those prone to yellowing. Titanium dioxide for ordinary plastics generally does not undergo surface treatment. The reason is that it usually uses conventional hydrated alumina inorganic coated titanium dioxide. When the relative humidity is 60%, the adsorption equilibrium water is about 1%. When the plastic is extruded at high temperature, the evaporation of water will cause pores on the smooth plastic surface. This kind of titanium dioxide that is not coated with inorganic substances generally has to undergo organic surface treatment (polyol, silane or siloxane). Because titanium dioxide plastic is different from titanium dioxide for coatings, the former is processed and mixed in a low-polar resin through shearing force. The organic surface-treated titanium dioxide can be better dispersed under proper mechanical shearing force.
With the continuous expansion of the application range of plastic products, many external plastic products, such as plastic doors and windows, building materials and other outdoor plastic products, also have high requirements for weather resistance. In addition to the rutile titanium dioxide must be used, surface treatment is also required. This surface treatment generally does not add zinc, but only adds silicon, aluminum, zirconium and so on.
According to the above introduction, the quality requirements for titanium dioxide used in plastic are summarized as follows:
1. Hiding power: Titanium dioxide with good hiding power makes the plastic products lighter and thinner;
2. Whiteness: It determines the appearance of light-colored or white plastic products;
3. Dispersibility: It affects the production cost of plastic products. The poorly dispersed titanium dioxide in plastic products will affect the smoothness and brightness of the products;
4. Weather resistance: Plastic products used outdoors and plastic doors as well as windows must ensure the weather resistance of titanium dioxide.