Titanium dioxide is a very stable white inorganic pigment with non-toxic, high whiteness and high brightness properties. It is considered to be the best white pigment in the world, accounting for about 80% of all white pigments used. . Titanium dioxide is widely used in coatings, plastics, papermaking, printing ink, rubber and other industries. Because titanium dioxide has many uses closely related to the national economy, it is known as the "barometer of economic development."
The coating industry is the largest application area of titanium dioxide, and the usage of titanium dioxide accounts for about 60% of the total demand for titanium dioxide. Its excellent tinting power and hiding power make the paint colorful and long-lasting, and play a certain protective role in the stability of the medium.
As the second largest application field of titanium dioxide, the plastics industry accounts for about 20% of the total demand for titanium dioxide. Adding titanium dioxide to plastics can significantly improve their heat resistance, light resistance and weather resistance, enhance mechanical strength and extend service life. We will not go into details about the proportion of other industries. It is worth mentioning that except for high-end brands that need to be imported, China is completely self-sufficient in titanium dioxide, and its production capacity leads the world.
Titanium dioxide production capacity in China
According to data from the United States Geological Survey on June 5, 2024, China will maintain its global market leadership with an astonishing 5.5 million tons of titanium dioxide production capacity in 2023, accounting for 56% of the market share, far exceeding other countries.
According to the latest statistics, in May 2024, China's titanium dioxide production reached 413,900 tons, a month-on-month increase of 1.51% compared with the previous month, and a substantial increase of 23.12% compared with the same period last year. From January to May this year, the cumulative production of titanium dioxide has reached about 1.9938 million tons, an increase of 20.91% year-on-year, and an increase of about 344,800 tons.
China has become a major producer and consumer of titanium dioxide, and domestic titanium dioxide has partially replaced it. According to Chinese customs statistics, China only imports a small amount of titanium dioxide, and in 2023, China's titanium dioxide imports will be less than 100,000 tons; with the continuous expansion of domestic production capacity, China's titanium dioxide exports have maintained a relatively fast growth rate, and in 2023, titanium dioxide exports will increase to 1.6418 million tons, accounting for about 40% of production.Let’s analyze in detail the application of titanium dioxide in plastic modification.
Application of titanium dioxide in plastic modification
As mentioned above, the plastic industry is the second largest application industry of titanium dioxide. Usually, the consumption of titanium dioxide in the plastic field accounts for 20% of the consumption of titanium dioxide in the application field. Among the more than 500 titanium dioxide brands in the world, more than 50 brands are dedicated to plastics.
In addition to its high hiding power, high tinting power and other pigment properties, the application of titanium dioxide in plastic products can also improve the heat resistance, light resistance and weather resistance of plastic products, protect plastic products from ultraviolet light, and improve the mechanical and electrical properties of plastic products.
Titanium dioxide is used in almost all thermosetting and thermoplastic plastics, generally in an amount of 1% to 5%. It can be mixed with resin dry powder or with liquid containing plasticizer. Titanium dioxide can also be processed into masterbatch before use.
Most titanium dioxide used in plastics has a fine particle size (0.15~0.3μm), which can obtain a blue base color and has a shielding effect on most yellow-phase resins or resins that are prone to yellowing.
Titanium dioxide used in plastics generally undergoes organic (polyol, silane or siloxane) surface treatment. The treated titanium dioxide can be dispersed relatively well under appropriate mechanical shear force.
The quality requirements of titanium dioxide for plastic products are:
Weather resistance: Plastic products used outdoors and plastic doors and windows must ensure the weather resistance of titanium dioxide.
Whiteness: determines the appearance of light-colored or white plastic products.
Dispersibility: affects the production cost of plastic products. Poorly dispersed titanium dioxide in plastic products will affect the smoothness and brightness of the products.
Hiding power: Titanium dioxide with good hiding power produces lighter and thinner plastic products.
Challenges faced by China's titanium dioxide industry
Although China's titanium dioxide production capacity leads the world, there is still a certain gap in product quality compared with foreign high-end titanium dioxide. This is mainly reflected in key indicators such as whiteness, tinting power, hiding power and weather resistance. Therefore, China's development in the titanium dioxide industry is not just a simple expansion of production capacity, but also needs to focus on improving product quality and technological innovation.
The improvement of titanium dioxide product quality is closely related to its production process. At present, there are two main methods for preparing titanium dioxide in the world-chloride process and sulphate process.
1) Chloride process
The production process of titanium dioxide by chloride process is to mix rutile or high-titanium slag powder with coke and then perform high-temperature chlorination to produce titanium tetrachloride, which is then oxidized at high temperature, filtered, washed, dried and crushed to obtain titanium dioxide products.
Its production process flow chart is shown in the figure:
Characteristics of the chloride process: The chloride process has high yield, low energy consumption, and high resource utilization; the titanium dioxide products produced are of excellent quality, with excellent whiteness and hiding power. The quality of this type of titanium dioxide product is highly stable, with fewer impurities and greater color-reducing power. When its particle size is uniform, it also has strong dispersibility. The chloride process produces less waste and has less impact on the environment.
2) Sulphate process
The sulphate process is a traditional titanium dioxide preparation process, and its production process is mainly divided into acidolysis, leaching, hydrolysis and calcination stages. Ilmenite reacts with sulfuric acid to generate titanyl sulfate; then, through hydrolysis, titanyl sulfate is converted into metatitanic acid; then, through dehydration, roasting and other processes, metatitanic acid is converted into titanium dioxide.
Its production process flow chart is shown in the figure:
Characteristics of sulphate process: Sulphate process has the advantages of mature technology, simple equipment and low investment. However, sulphate process will produce a large amount of wastewater, waste gas and waste residue, which will cause certain pressure on the environment; secondly, the yield of this method is low, the energy consumption is high, and the utilization rate of resources needs to be improved; the quality of titanium dioxide products produced by sulphate process is relatively poor, and the whiteness and hiding power are slightly inferior.
At present, the chloride process has become the mainstream in the world. About half of the world's total titanium dioxide production is chlorination products. Major titanium dioxide manufacturers in the world basically adopt the chloride process. However, due to the complex process, complex equipment and materials, and expensive equipment and materials of the chloride process, the sulphate process still dominates in China. According to statistics from the Titanium Dioxide Sub-Center, in 2023, the output of titanium dioxide by the chloride process in China accounted for about 16.6% of the annual output, while the output of titanium dioxide by the sulphate process accounted for about 83.4% of the annual output.
Since China mainly produces titanium dioxide by sulfuric acid, the product quality of titanium dioxide is often at a low level when competing with international chemical companies, which directly leads to the difficulty of selling titanium dioxide at a high price when exported. From January to November 2023, the average import price of titanium dioxide was US$3,476.93/ton, a year-on-year decrease of 5.13% compared with US$3,665.09/ton in the same period last year; from January to November, the average monthly export price of titanium dioxide was US$2,189.87/ton, a year-on-year decrease of 20.73% compared with US$2,762.71/ton in the same period last year.
In recent years, with the development of China's economy and the upgrading of its industrial structure, the market has increasingly stringent requirements on the performance of various materials. This trend has also indirectly promoted the continuous improvement of the quality and performance of titanium dioxide, an important chemical raw material, to meet the growing demand for high-end applications. At the same time, with the advancement of process technology and the leadership of leading enterprises, the production capacity of domestic chloride-based titanium dioxide is also constantly improving, which provides strong support for the high-end transformation of China's titanium dioxide industry. In the future, as China's chloride-based titanium dioxide production capacity is gradually put into production, domestic companies will compete with overseas companies in the high-end titanium dioxide market, and are expected to open up incremental space in emerging fields.