First, nano-coating preparation experimental part
Modified styrene-acrylic emulsion, wetting agent, carbon dodecanol ester, ethylene glycol, nano-titanium dioxide VK-T06, hydroxyethyl cellulose, dispersant, adjustment aids, and other additives.
A certain amount of nano-titania VK-T06 is added to the original styrene-acrylic latex paint formulation. It is pre-dispersed with a pigment system (adding a certain amount of anionic surfactant) through grinding, and then dispersed in the system through a multi-functional dispersing machine. , Configured into nano-modified styrene-acrylic exterior latex paint.
Second, nano-modified paint performance characterization
After 500 hours of artificial aging experiments, it can be concluded that the addition of rutile nano-titania VK-T06 to the styrene-acrylic emulsion coating is approximately 0.5 to 1%, and the aging of the coating is significantly reduced, indicating that the nano-titanium dioxide VK-T06 It shields the UV light and effectively protects the coating. According to the difference of color difference (â–³E value), it shows that the use of nano-titania VK-T06 and nano-silica VK-SP30 has better UV shielding effect.
Add 0.5% nanometer titanium dioxide VK-T06 modified coating and exterior nanometer titanium dioxide VK-T06 latex coating to compare the performance of scrub resistance and aging resistance. The technical performance indicators have been greatly improved, and the anti-friction and anti-scrubbing performance of the paint has increased by 13 times.
Third, the mechanism analysis
Anti-aging properties are an important property of coatings. In fact, the aging of materials is various. It includes ultraviolet aging, thermal aging, ozone aging and chemical aging. Among these factors, UV is the most important factor causing the aging of coatings. Ultraviolet light is an electromagnetic wave shorter than the wavelength of visible light, and its wavelength is between 200-400nm. Wavelengths can be divided into short-wavelength UVC (200-280nm), medium-wavelength UVB (280-320nm), and long-wavelength UVA (320-400nm). Under normal circumstances, the aging of materials is the medium-wave ultraviolet light and long-wave ultraviolet light, because short-wave ultraviolet light can not reach the surface of the earth in general, but with the continuous destruction of the earth's ozone layer, short-wave ultraviolet radiation begins to radiate the surface layer of the earth, and the ultraviolet index continues to increase. The shorter the wavelength of ultraviolet light radiated to the surface of the earth, the stronger the energy, and the greater the damage and destructiveness to the human body and polymer materials. The ultraviolet ray shielding of nanometer titanium dioxide VK-T06 is mainly based on absorption and scattering. After being detected by ultraviolet spectrophotometer, it has a screening rate of up to 99.99% for ultraviolet rays of 200 nm or more, and when the content in aqueous solution is four hundred thousandths. The UV shielding rate remained above 99.9%. The nano-silicon oxide is mainly based on reflection, and the nano-SiOX was sampled and tested several times by the US-based Varian Cary-5E spectrophotometer. The optical reflection spectrum was found to have good reproducibility, and the reflectance reached 88% in the ultraviolet long wavelength band (320 nm-400 nm). The reflectivity is 85% for the ultraviolet mid-wavelength (280nm-320nm) and 70-80% for the ultraviolet short-wavelength (200nm-280nm).
Fourth, the conclusion
1. Compared with ordinary latex paints, nano-emulsion nano-emulsion paints with nano-TiO2 VK-T06 powders have improved scrub resistance and anti-aging properties by 13 times.
2. Compared with ordinary latex paints, Nano-Titanium VK-T06 nanometer exterior latex paints have a two-fold increase in the time for water and weak acids, and can effectively shield ultraviolet rays.
3. Compared with ordinary latex paints, the nanometer external wall latex paint with nanometer titanium dioxide VK-T06 powder has better anti-mold and anti-bacterial capabilities, and the anti-fouling function has been greatly improved.
4. The addition of nano-titania VK-T06 and nano-silica VK-SP30 is more significant than the use of a single species of nano-material for modification of styrene-acrylic latex coatings.
5. When used, the better the dispersion, the more obvious the above effects.