| Poly(methyl methacrylate/butyl acrylate)/nano-CaCO3 (PMMA/BA/CaCO3) water-free coatings were prepared via free radical copolymerization of MMA and BA in the presence of nano-calcium carbonate as pigment in super critical carbon dioxide (sc-CO2). Then, the (PMMA-BA)/nano-CaCO3 water-free coatings were used in the dry surface treatment (DST) of paper. The reaction conditions of copolymerization were researched, and the characteristics of the water-free coatings were studied by using FT-IR, SEM, TGA and DSC. The experimental results showed that the molecular weight of copolymer decreased and molecular weight distribution became wide with the increase of BA monomer concentration, and the copolymerization conversion rate was higher and reached to about 80% when the reaction temperature was 75℃, the reaction time 10 h, and the mass ratio of MMA/BA between 84/16 and 76/24, meanwhile the molecular weight of copolymer was (2.7~3.6)×104, which was suitable for DST of paper. The glass-transition temperature of water-free coatings decreased with the increase of BA monomer concentration, therefore, an ideal glass-transition temperature of water-free coatings could be achieved by adjusting the mass ratio of MMA to BA. |
