Research on Anatase Titanium Dioxide for Camouflage Coating

Abstract: Camouflis synonymous with the army, is also the most popular outdoor decoration. Although camouflage is synonymous with the army, but now popular outdoor sports will adopt this decoration way, such as physical strength training, field survival training, long-distance cross-country competition, CS competition, etc. Will take camouflage decoration, daub to the most obvious parts, such as face, arm, the scope of application determines the camouflage color bright, easy to apply, easy to clean, for its special titanium dioxide in particle size, dispersion requirements; although the demand for camouflage paint is small, but its high added value, high technical content, camouflage coating has become the new favorite of the major paint manufacturers. The main components of coating are filler, base material, auxiliary agent, solvent, titanium dioxide is the most important white pigment, is the most important filler of coating.

Key words: Camouflage paint; Production process; Titanium dioxide

1. The basic concept of anatase dioxide

Titanium dioxide, titanium dioxide is titanium dioxide, molecular weight of 79.88, white powder, density of 3.84 melting point up to 1500℃, effective water absorption is 0.02%. In the high-temperature state, the heating was converted to a rutile-type crystal with a melting point of 1800℃ and a refractive index of 2.55. In the chemical stable state, light, heat, acid and alkaline [1]. Comprehensive color force, strong dispersion force. Suzi and the temperature rise, showing a yellow state, insoluble in water. In the organic acid, inorganic acid, can be dissolved in concentrated sulfuric acid, alkali, hydrofluoric acid.

1.1 Physical characteristics

Daily white pigments, if the density of titanium dioxide powder is small. Anatase dioxide becomes rutile type at high temperature. With the melting point and boiling point change of titanium dioxide, the action of material fiber changes. Titanium dioxide has high whiteness and strong coloring force. Weather resistance of titanium dioxide action, after cracking, crushing and stripping, the formation of titanium dioxide test plate, stable after ten years of action. With the enhancement of titanium dioxide color force and durability, the plastic effect is stable and effective.

1.2 Chemical characteristics

Titanium dioxide titanium dioxide chemical properties are stable, is an acidic oxide. At normal temperature, it will not react with other element compounds, and it does not play a strong role in oxygen, nitrogen, phosphoric acid, hydrogen sulfide, and carbon dioxide. Not used in water and dissolved in hydrofluoric acid. Under the action of light, titanium dioxide will continuously redox reaction, the comprehensive photochemical activity is obvious. Photochemical activity is a kind of anatase titanium dioxide formed under ultraviolet irradiation. Its comprehensive properties are obvious. Under the action of photosensitive oxidation catalyst of organic compounds, the goal of reduction catalysis is achieved through photosensitization.

1.3 Use analysis

Anatase type titanium dioxide is mainly used in the manufacturing process. In the use of basic raw materials such as coatings, papermaking and rubber processing, anatase titanium dioxide can expand the level of ceramic processing industry. In the ceramic processing process, quality, machinery, material technology varieties, can be widely used in the anatase titanium dioxide processing process.

1.4 Chemical fiber grade anatase type titanium dioxide

Chemical fiber type anatase titanium dioxide process is the use of polyester fiber, viscose fiber function fusion, after the chemical action of fibrosis extinction agent, to achieve the improvement of the product. The production process needs to be evaluated in strict accordance with the operation specification requirements of quality control, needs refined and rigorous management, and the comprehensive quality level is stable and effective.

In the process of product processing, attention needs to be paid to the distribution assessment of product granularity. From the dispersion stability, water-based dispersion performance, soft color ratio and other contents, attention should be paid to adjust the dispersion particles of ethylene glycol, and pay attention to the identification of covering performance. Under the action of acid and base, attention should be paid to the occurrence and development of harmful property impurities. In the chemical fiber production and processing process, the secondary condensation is used to evaluate the white degree and color measurement level, and pay attention to the packaging and transportation management of products. In the process of transportation and loading and unloading, light packing and special packaging methods are adopted to avoid rupture problems. In the storage of products, it is necessary to ensure dry ventilation, use sleeper cushion, do a good job of moisture management, avoid filling and stacking.

2. Research on titanium dioxide used for camouflage coating

2.1 Reduce the heavy metal content

Camouflage paint is mainly used at face, body daub plays certain decorative effect, because of direct contact human body, heavy metal content requirement is higher.

For the control of heavy metals first from the source control, that is, the control of titanium ore heavy metals, according to the heavy metal content of each ore powder, effectively control the heavy metal content of titanium dioxide.

Secondly, two vacuum water washing; under normal conditions, the chemical composition of the slurry after hydrolysis is generally: TiO2,160~180g / L; H2SO4,22%~30%; FeSO4 · 7H2O, 200~250g / L. The content of each component will vary slightly according to the different hydrolysis process. This suspension system is easy to separation of solid liquid, but due to the surface of hydrated titanium dioxide adsorption a lot of mother liquor, and the mother liquid contains a lot of ferrous sulfate, and magnesium, aluminum, chromium, vanadium, manganese, copper, lead and other metal sulfate, the existence of these impurities will seriously affect the purity of the product and the application performance of outdoor camouflage paint. Therefore, after hydrolysis, metanic acid must be washed before calcination. Using the insolubility of hydrated titanium dioxide and the solubility of impurity ions, the impurity ions are removed by means of water, including the removal of a large amount of dilute sulfuric acid adsorbed by mettitanium acid, so as to achieve the purpose of purifying hydrated titanium dioxide. After one wash, it is difficult to wash the impurity ions contained in metatanic acid to a very low concentration. Moreover, in the process of washing, some metal ions in partial titanic acid, especially Fe2 +, may be oxidized to form Fe3 + due to the decrease of acidity in the later stage of washing, and the formed part of Fe (OH) 3 precipitation mixed in the filter cake cannot be removed, which affects the iron content in the filter cake. Therefore, after a water are configured a bleaching process, is to wash after partial titanium acid slurry add concentrated sulfuric acid and reducing agent, the process of washing metal precipitation dissolved for ions, high oxide (mainly iron) reduction to low oxide, the second wash (also known as rinse) to remove and achieve the purpose of further purification partial titanium acid.

2.2 Ensure the anatase crystal type content

According to the nature of camouflage coating, only exists in human body for a short time, the weather resistance is not high, but the gloss, brightness and other performance requirements; therefore, titanium dioxide for outdoor camouflage coating can use titanium dioxide, because titanium dioxide hardness is low, easy to be ground, titanium dioxide fineness is small, used for high gloss, good brightness, effectively improve the beauty of camouflage coating.

After filtration, bleaching and salt treatment, the extrusion pump is squeezed into the internal combustion rotary kiln. Calcination is a strong heat absorption process, mainly using flue gas and material contact, with high energy to slurry moisture, titanium dioxide particles of moisture, titanium dioxide dioxide. Calcination process is mainly divided into three stages, is divided into drying area can be 250~800℃, different changes, can be divided into drying area 800~860℃ and particle growth area 860~950℃ three areas. In the crystal type conversion zone, the growing anatase type crystal to the rutile type conversion. The antitanium acid obtained by general sulfuric acid contains anatase microcrystal, which is obtained after calcination. This anatase crystal is usually stable below 900℃, and when the temperature exceeds 950℃, it begins to convert to rutile crystal. Therefore, it is very important to control the temperature. However, we need the titanium type crude in calcination temperature control is not very stable, easy to rutile titanium dioxide, titanium type and the titanium and rutile calcination temperature interval is small, easy to convert each other, so need to handle before calcination, add a certain amount of particle growth inhibitors, stable titanium dioxide type, inhibit the titanium dioxide particles are too large, ensure smooth particle surface, particle size. In addition, when calcined, because the temperature in the kiln is not completely easy to control, it is easy to lead to the sintering of titanium dioxide, that is, before adding a certain amount of kang sintering agent before entering the kiln to prevent titanium dioxide from being burned and yellow, and produce anatase crude with excellent catalytic activity.

The partial ic acid obtained after hydrolysis and washing also needs to go through bleaching and other processes to break its aggregation form and reduce the particle size.but, Due to the particularity of TiO 2 particles in the formation process, Its surface also adsorbed a large amount of free water and acid, Also contains part of the crystalline water and the bound acid, By using the calcination, Can remove this water and acid, But the direct calcination requires a higher temperature, Moreover, in the process of crystal type growth and stabilization after the dehydration and desulfurization, Not easy to control, The resulting TiO 2 particles are very hard, The color is either partial yellow, gray or dark yellow, Even a gray color, like a cement; If the calcination temperature is not increased, Then the sulfur in the partial titanium acid can not be removed, The resulting material pH is too low, High oil absorption capacity, Poor achromatic force, Failure to meet the performance requirements used for the catalyst, Therefore, anic acid must be treated before calcination, Add a certain amount of salt treatment agent (i. e. particle growth inhibitor and anti-sintering auxiliary agent, Collecknown as salt treatment agents), The dehydration and desulfurization process can be completed at a lower temperature, And in the high temperature section of the crystal type growth and transformation is relatively stable and complete, The resulting products have uniform particles, moderate size (nanoscale), appropriate hardness, Than the surface size is fully suitable for doing the catalyst carrier, All the indicators are in a better range.

Anatase type titanium dioxide commonly used salt treatment agent has potassium salt, sodium salt, and with phosphoracid or phosphate, in addition to antimonate, tungstate, hydrofluoric acid or fluoride, among which the most used is potassium carbonate or potassium sulfate and phosphoric acid. Potassium salt is a rutile type negative catalyst, is the anatase type stabilizer, can inhibit the product crystal type to rutile type conversion, but also can reduce the calcination temperature, improve the product color force, whiteness and loose type, and can adjust the acidity, increase the amount can increase the product pH, water soluble salt increase, reduce the oil absorption volume.

2.3 Organic envelope

Camouflcoating directly applied to the human body, the nature of organic coating, can not have harm to human body, outdoor camouflage coating special titanium dioxide choose propylene glycol as organic coating agent; propylene glycol is a colorless, odorless, sweet, smooth appearance, is an organic matter, can absorb moisture from the air, titanium dioxide using propylene glycol as organic coating agent no harm to human body, and can increase the titanium dioxide in camouflage paint miscibility, and because of the propylene glycol water absorption, in camouflage coating applied to the body can absorb the moisture in the air, increase the moisture of the skin, reduce the damage to the skin [2].

3.The process of special anatase titanium dioxide for camouflage coating

In the production and processing process of composite titanium dioxide, it is necessary to pay attention to the evaluation of the process steps, refine the calcination of kaolin particles, and do a good job in refining, pulping, hydrolysis, washing, crystallization and other processes. In the process of pulping, the kaolin superfine powder filtration after calcined slurry coal is needed, and the suspension of 10%~30% is used. In the process of hydrolysis coating, pay attention is paid to the assessment of suspended liquid amount, stirring to the same temperature, the control temperature is between 80 and 90℃, 15% inorganic titanium salt modified film is added, and the PH value of the control system is between 1.0 and 2.0. In the process analysis of titanium dioxide, combined with the sulfuric acid acidification process, extract the immersion reduction value, through sedimentation, filtration, crystallization, separation, hydrolysis, washing, drying, calcination and other ways, to meet the preparation requirements of process booster agent [3].

Chemical fiber anatase dioxide is mainly polyester fiber extinction agent, production and processing process, and anatase titanium dioxide production process is similar. According to the requirements of the key particles, adjust the position of the particles to avoid uneven distribution of particles, less fine particles and more coarse particles. In the water and thermal decomposition process, the dispersion and stability method is adopted to optimize the purity level of the product.

In the preparation process of anatase dioxide fibrosis, the operation process is needed to optimize the preparation process, and the crystallization is precipitated through sulfuric acid solution, infiltration reduction and sedimentation titanium dioxide liquefaction filtration. After the filtrate was filtered, the booster was added, and the crystal hydrolysis process was performed. A large amount of titanoid precipitate was precipitated, and the filtered titanoid solid was isolated. Tic acid, as the original material, is adjusted by the concentration of oxygen and titanium sulfate, and then precipitated by salt treatment, and dried after washing with water. Control the ratio F value of concentrated titanium liquid. In the hydrolysis process, appropriate filtration cooling and precipitation out of crystallization is needed to control the filtration liquefaction process. According to the appropriate amount of the hydrolysis process, the total amount of titanium dioxide, after the calcination of the rotary kiln, the control temperature of the kiln is about 960℃. After salt treatment, alkali neutralization can be adopted, adding sodium carbonate and sodium hydroxide colleagues. According to the control evaluation method of hydrochloric acid treatment, the total ratio level of salt treatment should be adjusted appropriately, the calcination temperature is adjusted, the dosage is improved, the crushing amount, etc., and the F value is obtained after adjustment to meet the reasonable requirements of the ratio operation ratio.

Anatase fibrosis titanium dioxide is a more practical way, in the process needs strict control management operation specification requirements, optimize the preparation control process, combined with the relevant concentration of titanium liquid F value analysis, after hydrolysis to obtain the right amount of crystals. In the process of salt treatment and control, it is necessary to appropriately increase the sum of salt treatment and dosage, adjust the calcination temperature and feed quantity level appropriately, and adjust the organic speed of [4] after crushing. In the preparation of anatase titanium dioxide, it is necessary to control the particle distribution of titanium dioxide, moderate adjustment, optimize the particle performance, to meet the actual production and processing requirements of sharpened titanium dioxide.

4. Conclusion

To sum up, through the ore, water washing titanium dioxide control of heavy metal content, through calcination temperature control crystal conversion, through the use of propylene glycol organic coating production titanium dioxide, the product low heavy metal content, soft particles, high gloss, non-toxic titanium dioxide, can be used in camouflage paint. Through the physical and chemical processing and production process evaluation, quickly optimize the design of the structure, pay attention to the analysis of the relevant test operation process and parameter level, and strictly standardize the control standards and technical processes. According to a series of various parameters and the requirements of combined planning and management, in the hydrolysis process, the F value level of concentrated titanium liquid is strengthened, the pH value is controlled at about 2, and the crystal quantity is appropriately adjusted and gradually increased. Under the condition of constant effective hydrolysis conditions, the advantageous value characteristics of strengthening the performance of the pigment are maintained. After the necessary hydrolysis generation, the particle distribution of biased acid aggregates is gradually uniform, which can be reasonably controlled within the reasonable range of micron. Make full use of salt treatment process, adjust the level of titanium dioxide to particles, can better adjust the content of titanium dioxide, to achieve the operation goal of camouflage processing.

References:

[1] Li Jinze, Li Xuemin, Wang Ying. Overview and research progress of titanium dioxide [J]. Dye and Stain, 2022,59 (05): 12-19 + 40.

[2] Jin Bin. Systematic study on improving the quality of anatase titanium dioxide produced by sulfuric acid method [J]. Chinese Coatings, 2010 (12): 6.

[3] Zou Jianxin, Wang Jun. Study on optimization of preparation process parameters for anatase titanium dioxide [J]. Chemical Industry Progress, 2004 (02): 185-187.

[4] Luo Zhiqiang. Effect of calcination temperature on the performance and particle size of anatase titanium dioxide pigment [C] / / National Titanium dioxide Industry Annual Conference, 2