Preparation and Application of Nano-TiO2 in Coating
Nano titanium dioxide is an nanoparticle with unique small size effect, surface and interface effect, quantum size effect and macroscopic quantum tunneling effect.
Currently, the preparation methods of nano-TiO2 powder can be summarized into two categories as gas and liquid methods. Although the gas phases nano-TiO2 powder prepared by high purity, small particle size, and monodispersity is good, but the preparation of complex equipment, energy consumption and high cost. In contrast, low temperature liquid phase synthesis method with simple equipment, easy operation, etc., is widely used in laboratory and industrial preparation method. Preparation of nano-TiO2 in the liquid phase method, the sol - gel method and alkoxide solution to the expensive titanium alkoxide as raw materials, and must be calcined at high temperatures (typically> 800 ) to get the rutile-type product.Hydrothermal been able to directly generate the crystalline TiO2 product, but its equipment requirements, operation complexity, energy consumption. Resulting in a serious subject to the application of nano-powder powder quality and cost. Therefore, to explore performance, low cost and ease of industrial-scale production of nano-TiO2 powder in liquid phase synthesis of new technology, the excellent performance of nano-TiO2 play and promote their application in the fields of coatings is very important.
With TiCl4 (chemical pure,), hydrochloric acid (AR, concentration 36%), deionized water (resistivity 105╝S, homemade), ethanol (AR, concentration 98%), butanol (analysis pure), dispersant A (self) as raw materials. Cooled in an ice water bath, will slowly trickle TiCl4 in deionized water, stirring constantly, dubbed a certain concentration of aqueous solution placed on aging for 24 hours; take a certain amount of the solution and hydrochloric acid, deionized water, mixed and heated to 60 , constant stirring, the temperature in the heat 3 to 4 hours; will be the hydrolysis product filtered, washed until the filtrate was neutral, and no Cl-(check with a 0.1M solution of AgNO3 no white precipitate appeared), add the self-dispersing agent , the mixing state by adding acetic acid and n-butanol, continue stirring until the system became homogeneous and stable dispersion, spray-dried at 180 under the conditions of stability can be obtained rutile nano-TiO2 powder.
After the appropriate treatment of inorganic layering in the nanoTiOX, use the organic halogen silane as surface treatment. Then use a latex wall paint for the study styrene, styrene-acrylic latex paint in the original recipe to add a certain amount of the designed nano-TiO2 powder and nano-composite materials SiOX, first with the paint system (add a certain amount of anionic surface active agent) dispersed through the pre-grinding, and then dispersed in the system through the multi-function machines to fully dispersed, nano-modified styrene-configured latex wall paint.
By artificial aging experiments can be concluded that, in the styrene-acrylic latex paint by adding rutile nano-titanium dioxide and nano silica, titanium dioxide or single-or silicon oxide is added, the added amount of 0.4 to 0.5 percent, the aging of the coating was decreased, indicating that nano-titanium dioxide and nano-silica played a shielding effect of ultraviolet light, the effective protection of the coating. According to color difference (│ E values) display, indicating that nano-titanium dioxide and nano-silica with the use of UV-shielding better.
Anti-aging is an important property performance of coatings. In fact, aging of the material is multifaceted which includes UV aging, thermal aging, ozone, aging and chemical aging. Typically, Nickel oxide what causing the aging of material are UV ultraviolet andá long-wave ultraviolet rays. Because the short-wave ultraviolet light under normal circumstances can not reach the earth's surface, but with the continued destruction of the ozone layer, UV radiation, the earth began to surface, the UV index is increasing. The UV radiation to the earth's surface the shorter the wavelength, the stronger the energy, and polymer materials on the human body, the greater the danger and destructive. Nano-TiO2 for UV absorption and scattering of the shield is mainly detected by UV spectrophotometer, it more than 200nm UV light shielding rate of 99.99%, when the content in aqueous solution per 100,000 four seasons, the UV shielding rate remained at 99.9%. Nano-silica is based on the reflection-based, random testing of nano-SiOX repeatedly found that the optical reflection spectra and good reproducibility, long-wave band in the UV (320nm-400nm) reflectance of 88%.Rreflectance rate in the ultraviolet band (280nm-320nm ) is of 85%.Reflectance rate on short wave UV(200nm-280nm) still reaches 70-80%.Source:http://www. mhcocm.com
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MHC INDUSTRIAL (CHINA) CO, LTD,specializing in integrating development research and production of the optics coating material, the metal material, the rare earth material and so on, is a comprehensive enterprise.