Three main functions of titanium dioxide in plastics

Titanium dioxide is widely used in plastics for its three main functions: high hiding power, high color reducing power and pigment performance. In fact, in addition to these three functions, it can also improve the heat resistance, light resistance and weather resistance of plastic products, to protect plastic products from sunlight and improve the mechanical and electrical properties of plastic products.

Because the coating film of plastic products is much thicker than paint and ink, it does not require too high pigment volume concentration, plus it has high hiding power and strong coloring power, and the general dosage is only 3% to 5%. It is used in almost all thermosetting and thermoplastic plastics, such as polyolefins (mainly low-density polyethylene), polypropylene, ABS, polyvinyl chloride, etc. It can be mixed with dry resin powder or with the liquid phase of the plasticizer, and some of the titanium dioxide is processed into masterbatch before use.

Most of the titanium dioxide used for plastics has a relatively fine particle size. Usually the particle size of the titanium dioxide used for coatings is 0.2～0.4μm, while the particle size of the titanium dioxide used for plastics is 0.15～0.3μm, so that a blue background can be obtained. Phase, it has a masking effect on most resins with yellow phase or resins that are prone to yellowing. Ordinary titanium dioxide used for plastic made from conventional hydrated aluminum oxide, generally without surface treatment. This kind of inorganic-coated titanium dioxide has an adsorption equilibrium water of about 1% when the relative humidity is 60%. When the plastic is extruded at high temperature During processing, the evaporation of water will cause pores to appear on the smooth plastic surface.

Titanium dioxide that is not coated with inorganic substances generally has to undergo organic surface treatment. At the same time, it is because the titanium dioxide used for plastics is different from the titanium dioxide used for coatings. The titanium dioxide used for plastics is processed by shearing force in a low-polarity resin. After mixing, the organic surface treated titanium dioxide can be better dispersed under proper mechanical shearing force.

Through the use of rutile titanium dioxide, the performance of these plastic products can be improved, especially in 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 have high requirements for weather resistance can be improved very well.