Study On The Polyacrylic Acid Size Modified By Nano-TiO₂

Nano-TiO₂ is innocuous and scentless, It presents prominent photocatalytic activity, the power of absorbing ultraviolet radiation and reflecting infrared ray are strong. In addition, it can resist bacterial and sterilize. It has been used widely in the fields of coating, paper making, ceramic, cosmetic, industry activator, anti-microbial materials, environment protect, aviation and so on. Using nano-TiO₂ to modify traditional acrylic acid size, it can make acrylic acid size having an excellent performance.At present, the studies focus on the denaturalization of starch and development of new acrylic acid size .The main study of this paper is on the acrylic acid size modified by nano-TiO₂. Earlier acrylic size has the merits of adhesion and flexibility and demerits of hygroscope, tackiness and too soft film which limit the size using in large quantity .Although different kinds of polymerizing methods with several mixing proportion of monomer can improve its performance, but this improvement is very limited. So, this paper tries to use nano-TiO₂ modified the acrylic acid size, and expects to get an excellent performance.Because the particle size of nano-TiO₂ has large ratio of surface to volume, high surface activity, and the coordination number is badly lacking, so its surface presents surface activity very strongly. It can result in congregate each other, lastly forms large conglomeration. This influences the product quality eventually. So we must modify the surface of nanometer titanium dioxide, reduce its surface energy in order to improve compatibility with organic media. This paper uses oleic acid to coat the nano-TiO₂ powder. Oleic acid can use its double bond to take part in composition, oleic acid joins the nano-TiO₂ powder and acrylic acid monomer. And using IR, TEM, TGA to rate the effect of coating.In this paper, the study first analysis and designs the molecular structure and choose the monomer like acrylic acid,ethyl acrylate,butyl acrylate and methyl methyacrylate, confirms the optimized parameters, including the method of placing monomers,the whisking velocity,the temperature and lasting time of the chemical reaction,the choice and volume of the emulsion and the solicitation agent. Then, put the nano-TiO₂ powder coated by oleic acid with SDS and OP-10 together, dispersed by ultrasonic for half an hour, let them have a full mix, after that, take part in the composition of acrylic acid size. SDS and OP-10 as compound emulsifying agent , the proportion is SDS:OP-10 = 3.4:1, which account for 4% of the total monomers, choose (NH4)₂SO₄ to be solicitation agent which account for 0.8% of the total monomers.Through the experiments such as sizing and TEM,SEM testing to the different ratio of acrylic acid size modified by nano-TiO₂, a conclusion can be found that the performance improved when the ratio of nano-TiO₂ increased, but when it arrive a value, its performance become poor.