Application of the hottest titanium dioxide in pap

Application of titanium dioxide in papermaking industry

papermaking is the third largest user of titanium dioxide. Considering the production cost, titanium dioxide is generally not used in low-grade paper, mainly porcelain clay, talc powder, calcium carbonate, etc., but they will reduce the strength of the paper and increase the weight of the paper. Titanium dioxide must be used in decorative paper, biblical paper and banknotes (such as dictionaries, pictorials, magazine covers, computers, banknotes, copier paper and decorative paper). The paper using titanium dioxide has good whiteness, high strength, luster, thin and smooth, and does not penetrate during printing. Under the same conditions, the opacity is 10 times higher than calcium carbonate and talc powder, and the weight can also be reduced by 15%~30%

decorative paper, also known as titanium white paper, is mainly used as raw materials for making furniture, floors, wallpapers, etc. For paper with anti-aging requirements, rutile must be used; More rutile is used in high ash paper, which must use rutile, because the hiding power of anatase titanium dioxide cannot meet the requirements. Anatase titanium white is used in low ash paper, such as biblical paper and banknotes. Biblical paper requires paper to have a good opacity, which is generally satisfied by using anatase titanium white; Coinage paper also requires good opacity, and anatase type is mainly used. In China, the amount of titanium dioxide used in decorative paper is much higher than that of the other two varieties, which is determined by China's consumption level. Due to the large demand for house decoration and high-end furniture, the consumption of decorative paper is gradually increasing; Due to the use of titanium dioxide as raw material, the cost of Bible paper is much higher than that of ordinary paper. In view of the domestic consumption level, the market of Bible paper is very limited; The manufacture and use of coinage paper is controlled by the state, and the consumption is relatively stable, which will not affect the titanium dioxide market. According to incomplete estimates, the domestic titanium dioxide used for decorative paper is more than 30000 tons per year. The amount of titanium dioxide in decorative paper is 20 ~ 40%, and that in other papers is 1 ~ 5%. Due to the transformation of traditional cultural paper manufacturers to produce decorative paper, the output of decorative paper has increased rapidly, and the price of decorative paper has shown a downward trend in recent years

no matter what kind of paper (base paper), its production process is the same:

rutile can be used twice for paper with weather resistance and high ash content, and anatase type is used for paper with low weather resistance and low ash content. The main reason for deciding which titanium dioxide to choose is the cost of papermaking, that is, the cost performance ratio of titanium dioxide. As the cost ratio of titanium dioxide in papermaking is as high as 30 ~ 50%, the paper mill can be said to be haggling over the choice of titanium dioxide when meeting the requirements of users. If it can use anatase, it will never use rutile. The requirements of the paper industry for the quality of titanium dioxide are in the order of importance:

1) hiding power (opacity): the ability of paper containing the same titanium dioxide to cover the background color, which determines the cost performance of titanium dioxide. In short, titanium dioxide with high hiding power is generally expensive, but its use is small, so the cost of titanium dioxide per ton of paper may be low; Although the price of titanium dioxide with low hiding power is low, its consumption is large, resulting in an increase in the cost of titanium dioxide per ton of paper

2) Whiteness: the whiteness of titanium white determines the appearance of paper after molding

differences between rutile titanium dioxide and anatase titanium dioxide

I. physical properties

1) relative density

among commonly used white pigments, titanium dioxide has the smallest relative density, and among white pigments of the same quality, titanium dioxide has the largest surface area and the highest pigment volume

2) melting point and boiling point

because anatase will change into rutile at high temperature, the melting point and boiling point of anatase titanium dioxide actually do not exist. Only rutile titanium dioxide has melting point and boiling point. The melting point of rutile titanium dioxide is 1850 ℃, the melting point in air is (183015) ℃, and the melting point in oxygen enrichment is 1879 ℃. The melting point is related to the purity of titanium dioxide. The boiling point of rutile titanium dioxide is (3200300) ℃. At this high temperature, titanium dioxide is slightly beautiful and volatile

3) dielectric constant

titanium dioxide has excellent electrical properties due to its high dielectric constant. When determining some physical properties of titanium dioxide, the crystallization direction of titanium dioxide crystal should be considered. The dielectric constant of anatase titanium dioxide is relatively low, only 48

4) conductivity

the greater the deviation between the semi conductive conditional stress of titanium dioxide and the real stress borne on the sample; The conductivity of the "necked" afterbody increases rapidly with the increase of temperature, and it is also very sensitive to hypoxia. The dielectric constant and semiconductor properties of rutile titanium dioxide are very important to the electronic industry, which can be used to produce electronic components such as ceramic capacitors

5) hardness

according to the Mohs hardness scale, rutile titanium dioxide is 6 ~ 6.5, and anatase titanium dioxide is 5.5 ~ 6.0. Therefore, anatase is used in chemical fiber extinction to avoid wear of spinneret holes

6) hygroscopicity

although titanium dioxide has hydrophilicity, its hygroscopicity is not very strong, and rutile type is smaller than anatase type. The hygroscopicity of titanium dioxide is related to its surface area. Its large surface area and high hygroscopicity are also related to surface treatment and properties

7) thermal stability

titanium dioxide is a material with good thermal stability

II. Chemical properties

the chemical properties of titanium dioxide are extremely stable. It is a kind of acidic amphoteric oxide. It hardly reacts with other elements and compounds at room temperature, and has no effect on oxygen, ammonia, nitrogen, hydrogen sulfide, carbon dioxide and sulfur dioxide. It is insoluble in water, fat, dilute acids, inorganic acids and bases, and only soluble in hydrofluoric acid. However, under the action of light, titanium dioxide can undergo continuous oxidation-reduction reaction and has photochemical activity. This photochemical activity is particularly evident in anatase titanium dioxide under UV irradiation. This property makes titanium dioxide a photosensitive oxidation catalyst for some inorganic compounds and a photosensitive reduction catalyst for some organic compounds

3) dispersibility: dispersants are generally used in current papermaking processes, so there is little difference in the water dispersibility of titanium dioxide

4) weatherability: domestic rutile can meet the weatherability requirements of most papers, and only a few papers need rutile to provide high weatherability

5) retention rate: the paper industry reuses the filtered water or uses retention aids. Generally, the recovery rate of titanium dioxide is more than 99%. The reason why this indicator is retained is that international titanium dioxide companies provide retention agent formulas and application methods when promoting titanium dioxide for paper making, so as to improve service quality and increase product competitiveness