Market Dynamics

Comparison of application of the two processes in plastics products

Time: 2020-12-10 Source from: Titanos

(1) Requirements of plastics for the properties of titanium dioxide

The plastic industry is the second largest user of titanium dioxide, accounting for about 20% of the total demand for titanium dioxide in the world. It is the fastest growing field of titanium dioxide application in recent years, with an average annual growth rate of 6%. Among the more than 500 titanium dioxide brands in the world, more than 50 brands belong to plastic special-purpose type. The plastic industry is an important application field of titanium dioxide. In recent ten years, it has developed at an amazing speed in China. In 2019, the total output of the plastic products industry in China has reached 81.8417 million tons, with a year-on-year growth of 3.91%.

Adding titanium dioxide in plastics can improve the heat resistance, light resistance and weather resistance of plastic products, improve the physical and chemical properties of plastic products, enhance the mechanical strength of plastic products, and prolong their service life. Moreover, in recent years, with the strengthening of people's awareness of environmental protection and energy conservation, the pace of replacing steel with plastic in the future will be faster and faster, and the proportion of plastic products in our lives will be larger and larger. It is expected that in the near future, the demand for plastics will surpass that of steel, and the demand for titanium dioxide, the basic pigment for plastic fillings, will increase year by year. UPVC profiles are also playing an increasingly important role in the plastics industry, and are becoming an important application field that cannot be ignored in the TiO2 industry.

Titanium dioxide has two main functions in the plastic industry. One is the basic use of white pigment to provide cover (white coloring). The 2nd action is to block ULTRAVIOLET ray, use as agent of ultraviolet ray screen drawback, provide good weather resistance for the plastic product that uses outdoors. The titanium dioxide used in the production of ordinary plastics does not require weather resistance, but focuses more on the performance of pigments.

For titanium dioxide used in plastics, fine particles and good dispersibility are required. Good heat resistance and light resistance, the plastic molding process of heating and the finished products in the sun exposure and use process do not change color. Most plastics with titanium white particle size is relatively fine, usually paint with titanium white particle size of 0.2 ~ 0.4μm, and plastics with titanium white particle size of 0.15 ~ 0.3μm, so you can get a blue bottom phase, most of the yellow phase of the resin or easy to yellowing resin has a shielding effect. And using titanium dioxide instead of lithopone, the consumption of white pigment can be reduced by 50%~70%.


Ordinary plastic with titanium dioxide, generally without surface treatment, because the conventional hydrated alumina this kind of inorganic coating of titanium dioxide, when the relative humidity is 60%, the adsorption equilibrium of water at about 1%, when the plastic in the high temperature extrusion processing, water evaporation can lead to smooth plastic surface blowhole, this without inorganic coating of titanium dioxide, typically through organic surface treatment (polyol, silane and siloxane), because plastic in titanium pigment and coating in titanium pigment is different, the former is in the resin of low polarity, by mixing shear processing, organic titanium dioxide after surface treatment, under the appropriate mechanical shear force, You can spread it out better. In color masterbatch, due to the high PHR of TiO2, its dispersability becomes more important, so higher requirements are put forward for the surface treatment of titanium dioxide.

With the expansion of the plastic products application range, many external use plastic products, such as plastic doors and Windows, construction materials such as plastic products, outdoor weather resistance and have high requirements, besides must use the rutile titanium dioxide, surface treatment is needed, the surface treatment is generally not add zinc, only add silicon, aluminum, zirconium, etc. Silicon has the function of hydrophilic dehumidification, which can prevent pores caused by water evaporation in the extrusion of plastic at high temperature, but the amount of these surface treatment agents is generally not too much.

Titanium dioxide in polyolefin (such as polypropylene), sometimes cause plastic yellowing, this is because titanium dioxide and polyolefin containing phenolic antioxidants (BHT) caused by the reaction, titanium dioxide appropriate organic surface treatment can reduce the yellowing effect.


In hard polyvinyl chloride containing lead stabilizers, titanium dioxide will cause the resin to turn gray under Ultraviolet irradiation, because the titanium dioxide will be reduced to Ti2O3 after Ultraviolet irradiation, so that the lead in the lead stabilizer precipitation, this reaction is reversible. But the soft polyvinyl chloride (PVC) and the use of hard polyvinyl chloride (PVC) with tin stabilizer is not going to happen, also used in the melamine formaldehyde resin, but also because of the reducibility of resin itself, and the role of ultraviolet radiation, can also make the melamine decorative board (grey) color, if you want to use in the above-mentioned material, be sure to choose small high weatherability of rutile type titanium pigment chemical activity.

(2) Comparison between the two processes of titanium dioxide in the application of plastics

Learned, domestic plastic products, especially in high-end products, titanium dioxide is still used to use to import the chlorination production process process titanium white is given priority to, not only in whiteness appearance properties such as chlorination production process process titanium pigment is better than that of titanium dioxide sulfuric acid method, and on the hiding power, dispersibility, workability, especially for the outdoor UPVC plastic mechanical products for chlorination production process process rutile has incomparable advantages.

However, due to the characteristics of the plastic product, should be considered for its use titanium dioxide and other coatings, printing ink, paint, etc. When choosing different, mainly should be taken into account in accordance with the technical requirements of plastic products, such as plastic special products, must according to the product demand, carefully choosing products suitable to the special purpose of titanium dioxide, lest cause certain influence to the plastic product performance.


To be continued