The plastics industry is the second-largest consumer of titanium dioxide, accounting for approximately 18% of global demand; it has been the fastest-growing sector for titanium dioxide applications in recent years, with an average annual growth rate of 6%. Among the more than 500 titanium dioxide grades available worldwide, over 50 are specifically designed for plastics.
UPVC profiles—a major branch of the plastics industry and a key application area for titanium dioxide—have seen explosive growth in China over the past decade, expanding at an average annual rate of 10%.
In 2008, national profile production totaled 3.8 million tonnes, consuming approximately 135,000 tonnes of rutile-grade titanium dioxide. Based on the 10% annual growth rate, the industry's titanium dioxide requirement rose to approximately 150,000 tonnes in 2009 and reached 165,000 tonnes in 2010.
Incorporating titanium dioxide into plastics enhances the heat, light, and weather resistance of plastic products, improves their physicochemical properties, boosts mechanical strength, and extends their service life.
Furthermore, as public awareness regarding environmental protection and energy conservation continues to grow, the trend of replacing steel with plastic is accelerating, and plastic products are playing an increasingly significant role in our daily lives.
Titanium dioxide serves two primary functions in the plastics industry: first, it acts as a white pigment to provide opacity (white coloration); second, it serves as a UV-blocking agent, shielding against ultraviolet radiation and ensuring excellent weather resistance for plastic products intended for outdoor use.
Titanium dioxide used in the production of general-purpose plastics does not require weather resistance; instead, the emphasis is placed on pigment performance characteristics.
For plastic-grade titanium dioxide, requirements include fine particle size and good dispersibility, as well as excellent heat and light stability—ensuring no discoloration occurs during the heating involved in plastic molding or during the product's subsequent exposure to sunlight and use.
Most titanium dioxide grades for plastics feature finer particle sizes; while titanium dioxide for coatings typically has a particle size of 0.2–0.4 μm, the grade for plastics ranges from 0.15 to 0.3 μm. This finer size produces a blue undertone, which helps mask the yellowness of resins that are naturally yellowish or prone to yellowing. Furthermore, replacing lithopone with titanium dioxide can reduce the consumption of white pigment by 50% to 70%.
Comparison of Titanium Dioxide Produced via Two Processes for Plastic Applications
It is understood that the titanium dioxide currently used in domestic plastic products—particularly high-end ones—is predominantly imported material produced via the chloride process. Chloride-process titanium dioxide is superior to sulfate-process titanium dioxide not only in superficial properties such as whiteness but also in terms of hiding power, dispersibility, and processability; it offers unparalleled advantages, especially for outdoor UPVC plastic profiles requiring rutile-grade products made via the chloride process.
However, due to the specific characteristics of plastic products, the selection of titanium dioxide involves considerations that differ from those for coatings, inks, or paints. Decisions must be guided primarily by the technical requirements of the plastic products themselves; for instance, when dealing with specialized plastic-grade products, one must carefully select a titanium dioxide variant suited to the specific application to avoid compromising the product's performance.