Will titanium dioxide fade over time?
Among the many white pigments, titanium dioxide is definitely the most outstanding one. Compared with traditional white pigments such as lead white, zinc white, and zinc barium white, it has many excellent properties such as high refractive index, strong achromatic power, high covering power, good dispersibility, good whiteness and non-toxicity. So will titanium dioxide fade over time？
Known as the king of white paint. However, the overall success does not represent the individual. If the indicators are not qualified, they will also be rejected. So what indicators should titanium dioxide have in order to be considered successful?
1.1. The role of titanium dioxide fade in coatings
The coating is mainly composed of four parts: film-forming substances, pigments, solvents and additives. The pigments in the coating have a certain covering power, which can not only cover the original color of the object to be coated, but also give the coating a bright color. Realize the decorative effect of brightening and beautifying.
At the same time, the pigment is closely combined with the curing agent and the base material, which can enhance the mechanical strength and adhesion of the coating film, prevent cracking or peeling, and can enhance the thickness of the coating film, prevent the penetration of ultraviolet rays or moisture, and improve the coating film. Anti-aging and durability properties of the film, extending the service life of the coating film and the protected object
Among the pigments, white pigments are used in a large amount, and the performance requirements of coatings for white pigments:
① good whiteness;
② good grinding and wetting;
③ good weather resistance(decide on titanium dioxide fade)
④ good chemical stability;
⑤ small particle size, hiding power and dissipation High color strength, good opacity and gloss.
It is a kind of white pigment that is widely used in coatings. Its output accounts for more than 70% of inorganic pigments, and its consumption accounts for 95.5% of the total consumption of white pigments. At present, about 60% of the world’s titanium dioxide is used to manufacture various coatings, especially rutile titanium dioxide, most of which are consumed by the coatings industry.
Coatings made of it have bright colors, high hiding power, strong tinting power, low dosage, and many varieties, which can protect the stability of the medium, and can enhance the mechanical strength and adhesion of the paint film, prevent cracks, and prevent ultraviolet rays It can penetrate with water and prolong the life of the paint film. Almost every pattern in the colorful pattern paint is inseparable from titanium dioxide.
Different types of coatings for different purposes have different requirements for it. For example, powder coatings require rutile titanium dioxide with good dispersibility. Anatase titanium dioxide has low achromatic power and strong photochemical activity.
When used in powder coatings, the coating film is prone to yellowing. The rutile titanium dioxide produced by the sulfuric acid method has the advantages of moderate price, good dispersibility, good hiding power and achromatic power, and it is very suitable for indoor powder coatings.
In addition to good dispersibility, hiding power and achromatic power, titanium dioxide for outdoor powder coatings also requires good weatherability. Therefore, titanium powder for outdoor powder coatings is generally produced by the rutile type of titanium dioxide by the chlorination method.
2. Analysis of the influence of main quality fluctuations of titanium dioxide on coatings
As the white pigment of the coating, the whiteness of rutile titanium dioxide is very important, and it is one of the key quality indicators required by the coating. The poor whiteness of titanium dioxide will directly affect the appearance of the coating film. The main factor affecting the whiteness of it is the content of harmful impurities, because titanium dioxide is very sensitive to impurities, especially rutile titanium dioxide.
Therefore, even a small amount of impurities will have a significant impact on the whiteness of titanium dioxide. The whiteness of it produced by the chlorination process is often better than that produced by the sulfuric acid process.
This is because the titanium tetrachloride, the raw material used in the production of it by the chlorination process, has been distilled and purified, and its own impurity content is low. The raw material has a high content of impurities, and can only be removed by washing and bleaching and other process technologies.
2 Covering power
The covering power is the surface area of the object to be coated per square centimeter. When it is completely covered, the same area is applied. The greater the covering power of the titanium dioxide used, the thinner the coating film can be.
The amount of them required is also less. If the hiding power of them is reduced, in order to achieve the same covering effect, the amount of titanium dioxide required increases, the production cost will increase, and the amount of them will increase, which will lead to it in the coating. It is difficult to disperse uniformly in the paint, and aggregation occurs, which will also affect the covering effect of the paint.
3 Weather resistance
Coatings have high requirements on the weather resistance of it, especially for outdoor surface coatings, which require titanium dioxide with high weather resistance or ultra-high weather resistance. When using titanium dioxide with low weather resistance, the coating film will have problems such as fading, discoloration, chalking, cracking and peeling.
The crystal structure of rutile titanium dioxide is more compact than that of anatase titanium dioxide, and the photochemical activity is low, so the weather resistance is much higher than that of anatase titanium dioxide, so the titanium dioxide for coatings is basically all rutile titanium dioxide.
The main method to improve the weather resistance of titanium dioxide is to carry out inorganic surface treatment, that is, to coat one or more layers of inorganic oxides or hydrated oxides on the surface of titanium dioxide particles.
Rutile titanium dioxide is ultra-fine particles with large specific surface area and high surface energy. It is easy to aggregate between particles, and it is difficult to stably disperse in coatings. Poor dispersion of titanium dioxide will directly affect its optical properties such as achromatic power, hiding power and surface gloss in coatings, and will also affect the storage stability, fluidity, leveling, coating durability, and corrosion resistance of coatings.
In addition, rutile titanium dioxide also affects the production cost of coatings, because the energy consumption of grinding and dispersing operations is high, accounting for most of the total energy consumption of the coating manufacturing process, and the loss of equipment is large.
Jinan Hongquan Titanium Industry Co., Ltd.( Greatspring) is located in Jinan, a beautiful spring city. The company’s scientific research personnel sincerely cooperate with well-known domestic universities and various titanium dioxide production enterprises to study and produce active titanium dioxide pigments with great concentration. Some of its products have been widely used in chemical, textile, paper, plastic, paint and other production fields.
Titanium dioxide delivery
The company’s products (likeDongfang、Lomon Brand Lomon titanium dioxide) have been demonstrated by well-known national experts, and the conclusion is: “technological innovation is strong, improves the performance and utilization of pigments, reduces dosage, saves resources, economic benefits, no environmental pollution, in line with national industrial promotion and development strategies”