The application of titanium dioxide and its application index analysis

0 IntroductionTitanium white powder is the most important white pigment, accounting for 80% of all white pigment use, is also the most important product of titanium system, 90% of the world's titanium resources are used to make titanium white powder, is the third largest inorclement chemical after synthetic ammonia and phosphoric acid (in value). Titanium white powder is a kind of white inorder pigment which is widely used and in great demand. Many developed countries have included it in the list of key chemicals, in some countries and regions, their consumption is directly in line with gross national product (GNP), and even titanium dioxide per capita consumption as a measure of a country's economic development and people's living standards as one of the important indicators. Titanium white powder is divided into two categories: one is redstone type titanium white powder, its light resistance, strong weather resistance, more used in outdoor coatings and products; Titanium white powder has a high refrengation index, good chemical stability, weather resistance, whiteness, high color and cover, and non-toxic harmless, non-irritating effect on the human body, widely used in coatings, plastics, paper, ink, pharmaceuticals, fibers, cosmetics and other fields. Non-surfaced titanium dioxide usually does not meet the requirements of most high-grade applications and must be treated with one or more layers of inorganic or organic surfaces. Surface treatment is an important part of the process of titanium dioxide processing, the surface treatment process and conditions determine the surface properties and application properties of titanium dioxide, that is, determine the application of such titanium dioxide.1 titanium dioxide application area 1.1 coatingcoating is the largest user of titanium dioxide. In general, the consumption of titanium dioxide in the field of coatings accounted for 60% of the consumption of titanium dioxide applications, and it is also the largest use of paint pigments (all kinds of coatings in the titanium content of 10% to 35%). Here are a few types of coatings related to titanium dioxide applications.1.1.1 latex paintlatex paint is a water-based coating that is dispersed by adding pigments to the resin emulsion. Latex paint contains no solvent or contains a small amount of solvent, with weather resistance, washable, environmental protection and other advantages, widely used as architectural coatings, is one of the fastest growing paint varieties in recent years. Latex paint is divided into internal and external use, external coatings must use redstone-type titanium white; General latex paint processing processing process is: pigments, dispersants, water, desiccants and other premixed, high-speed stirring (or grinding) to a certain degree of fineness, and then add emulsion, other additives, high-speed stirring (or grinding) is the product.1.1.2 coils and iron coatings colored steel is a new variety developed in recent years, with strong durability, easy to use, beautiful, removable and other advantages by the user welcome, coil coatings and iron coatings also came into being. Coil coatings are coated on steel plates or other metal surfaces by a special paint machine and then baked and molded. Coil coatings can be divided into layer coatings and surface coatings, layer coating requirements are low, you can use domestic redstone-type titanium and epoxy resin, surface coating requirements are high, generally using imported redstone-type titanium dioxide powder and polyester resin.1.1.3 car paint car paint is high-grade and low-grade, the best is car paint, followed by truck paint and passenger car paint. Automotive paint mainly requires the weather resistance, gloss and cover of titanium dioxide. At present, can use in the car paint titanium brand is very few, are special imported chlorinated gold redstone type titanium white, such as R2310, R706 and so on. Domestic redstone type titanium white can only occupy the middle and low-grade car paint market.1.1.4 Powder CoatingsPowder Coatings are direct hot-melt mixtures of resins and pigments, additives, etc., so that the pigments are dispersed in the melted resin and then cooled and crushed. Since powder coatings are solvent-free, they do not cause environmental pollution when used, and powder coatings can be recycled during use, which is also beneficial for energy conservation. Powder coatings are sprayed with static electricity on metal parts such as home appliances and automotive parts, and can also be used in non-metallic products such as plastics and wood. Powder coatings are mostly made of redstone titanium.
1.2 plasticThe plastics industry is the second largest user of titanium dioxide, which typically accounts for 20% of the consumption in the field of plastics. Of the more than 500 titanium dioxide brands worldwide, more than 50 are plastic-specific. The application of titanium dioxide in plastic products, in addition to the use of its high cover, high coloration and other pigment properties, it can also improve the heat resistance of plastic products, light resistance, weather resistance, so that plastic products from ultraviolet light, improve the mechanical and electrical properties of plastic products. Almost all thermosoplastics use titanium dioxide, the general dosage of 1% to 5%, it can be mixed with resin dry powder, but also with the liquid containing plasticizer, as well as titanium white powder first processed into color master grains and then used. Most plastics use titanium dioxide powder particle size is relatively fine (0.15 to 0.3 m), so that you can obtain a blue background color, most of the resin with yellow phase or yellow resin has a masking effect. Plastic titanium dioxide powder is generally treated with organic (polyol, silane or silica) surface treatment, treated titanium dioxide, in the appropriate mechanical shear force, can be better dispersed.
plastic products on the quality requirements of titanium white is:(1) Weather resistance: outdoor use of plastic products and plastic doors and windows, etc. must ensure the weather resistance of titanium white; (2) Whiteness: determines the appearance of light or white plastic products;
(3) Dispersion: Affects the production cost of plastic products, the dispersion of bad titanium in plastic products will affect the smoothness and brightness of the products;(4) cover force: good titanium cover, the production of plastic products lighter and thinner.1.3 color master grain plastic master grain is a highly concentrated, high-efficiency color matching products, that is, pigments at abnormal concentrations evenly distributed in the carrier resin, and the formation of a certain particle size particles. It is mainly composed of core layer (pigment), conclication layer (coupled agent or surfactant), dispersion layer (lubricant or dispersant), mixed layer (carrier resin) and so on, widely used in blow film, injection molding, thermal pressure and other plastic products production. According to incomplete statistics, China's titanium dioxide used for master-color production of 2 to 30,000 t per year.the performance of -color master grain is usually shown in subsequent product applications, such as blow film or injection molding, therefore, the performance of titanium white in masterchrome is mainly reflected in the application process of masterchrome: (1) titanium coloring force: determine the amount of titanium used in plastic products of the same color; (2) Whiteness and chroma of titanium white: determines the appearance of light (white) plastic products with the same titanium content; (3) dispersion of titanium white: indicators that affect the production cost of master color particles and the appearance and gloss of plastic products; and (4) the processing performance of titanium white: affects the production cost of master grains. 1.4 Paper is the third largest user of titanium dioxide. Decorative paper, Bible paper and paper money are generally used titanium white powder, the use of titanium white powder paper, good whiteness, high strength, glossy, thin and smooth, printing without penetration, under the same conditions opacity than calcium carbonate, talcum powder 10 times higher, the quality can also be reduced by 15% to 30%. Decorative paper is also known as titanium white paper, mainly used in the production of furniture, flooring, wallpaper and other raw materials. For paper with anti-aging requirements, it is necessary to use gold-redstone titanium white, and more gold-redstone-type titanium white is used in high-ash paper, because the cover force of sharp titanium-type titanium can not meet the requirements. Sharp titanium-type titanium is used in low-ash paper, such as Bible paper and paper money. It is not fully estimated that the titanium white used to decorate paper in China exceeds 30,000 t per year. The amount of titanium white in decorative paper is 20% to 40%, and the amount of titanium white in other paper is 1% to 5%. The main reason for deciding which titanium white to choose in a paper mill is the cost of papermaking, that is, the cost-effectiveness of titanium white. Can use sharp titanium type titanium white never use redstone type titanium white. The paper industry's requirements for titanium-white quality are: masking force (opacity), whiteness, dispersion, weather resistance, retention rate. 2 Select the elements of titanium dioxide 2.1 color factor color is an important technical indicator of pigments. The color index of titanium white powder is whiteness. Even titanium dioxide of the same chemical composition, due to the different routes, raw materials, equipment, technical levels will also produce color differences, color light is certainly dependent on chemical composition, but the more important, often decisive factors are its particle shape, size, particle size distribution, crystal, impurity content. 2.2 cover force factor the optical nature of the covering force is caused by the difference in the refractive index between the pigment and the surrounding medium. The refractive index of gold-redstone titanium dioxide is 2.71, and the refractive index of sharp titanium-type titanium dioxide is 2.55, which is the white pigment with the highest cover. The masking effect is mainly caused by titanium dioxide scattering, or absorption caused by the presence of colored substances, or the above two reasons cause the intensity of the incoming light to decrease and the cover phenomenon appears. Therefore, the main reason for determining the cover force of titanium dioxide is related to the particle shape, particle size and particle size distribution of titanium dioxide in addition to chemical composition and crystal form. 2.3 Coloring Force Factor Coloring force is an important characteristic of titanium dioxide, i.e. the ability of the mixture to display its own color when mixed with another pigment. That is to say, for white pigments, when mixed with a dark pigment, the lighter the color of the mixture, the stronger its coloring force (coloring force). 2.4 Oil absorption factor The oil absorption is also one of the important pigment properties of titanium dioxide, which relates to the filling state of titanium white powder in the colorizer and can indicate its dispersion in the medium. It estimates the consistency of the coating before mixing the coating, guides the formulation of the coating, and can initially calculate its pigment volume concentration (PVC). 2.5 Chemical composition The chemical composition of titanium dioxide determines its chemical properties, in addition to reflecting a series of pigment properties of pigments, such as whiteness, coloration, oil absorption, etc., its application performance, such as weather resistance, dispersion, etc. also has a great impact. 2.6 Light resistance, weather resistance factors Titanium dioxide resistance and weather resistance is an important indicator to measure the performance of titanium dioxide applications, only after the application of titanium dioxide to related applications (such as automotive paint, profiles, etc.), this indicator is meaningful. In addition, to measure the light resistance and weather resistance of titanium dioxide to ensure that its application carrier weather resistance is better than titanium white powder. The main factors affecting the weather resistance index of titanium dioxide are its chemical composition, the chemical form of envelope substances, crystal structure, application formulation and so on.
2.7 gloss factor is The gloss of titanium dioxide is an important index to measure the application performance of titanium dioxide, usually titanium white powder has no luster, only after the application of titanium dioxide to related applications (such as automotive paint, ink, profiles, master grains, etc.), this indicator is meaningful. 2.8 volatile cents the volatiles of titanium dioxide are actually water content. Because its surface has a high energy and hydroxyl, so its surface always has to absorb a certain amount of water to reduce its surface energy, adsorption of water and titanium dioxide surface organic treatment, and its storage environment humidity and temperature. The volatility of titanium dioxide can not determine the quality of its products, depending on its application system. In general, the high and low volatility of water-based systems has little effect on applications, but for solvent-based systems and polyolefins and other systems, the lower the volatility, the better, because the high volatile score will affect its dispersion in the system and product quality. 2.9 Dispersion Factors is an important application index of titanium dioxide. Dispersion is also known as grinding dispersion or grinding wetting. Dispersion not only affects the antichromaction, cover force, oil absorption and other indicators of titanium dioxide, but also affects the gloss and weather resistance of coating film or profile molding. In the coating grinding dispersion, the dispersion of good or bad directly affect the length of grinding dispersion time, is one of the important economic indicators of paint production, and grinding time will also increase equipment pollution, so that the product whiteness is worse. In the production of plastic master grains or profiles, the dispersion directly affects the cycle of changing the head screen and the performance of the final product. 3 Precautions in the application of titanium dioxide 3.1 quality stability If some of its indicators are unstable, even if a certain indicator of titanium dioxide has been greatly improved, this is not the downstream user expected products, according to the changes in titanium dioxide quality indicators of the formula must be adjusted accordingly, otherwise product quality will be a problem. This is a matter of great concern to downstream users. 3.2 It is important to choose the right titanium dioxide and the right titanium dioxide product for this application. Now at home and abroad in the titanium dioxide market titanium white powder models have thousands of species, divided into general-purpose and special type two categories. Generic products are, as the name suggests, applicable in many areas, but there is a gap in a particular application area compared to specialized products in a particular area. If the plastics industry is very well used special titanium products for water-based coatings, there will be major quality problems. Therefore, for titanium dioxide manufacturers, to know which area their products are suitable for, not suitable for which field, to avoid the product is not suitable for the company's products in the field of application, so as to avoid many quality objections. The downstream users of titanium dioxide powder should also have some understanding of the products recommended by titanium dioxide manufacturers, can understand whether the same industry has enterprises in use, how to use, and the new product must be tested before entering the factory to determine whether this product is suitable, in order to avoid their own improper selection of products and cause unnecessary economic losses.