Enzymatic Modified Starch as Binder Component of Coating Color for Coated Paper

Coated paper is a type of printing paper; coated one or both sides, with or without supercalendar finishing. The uniformity of coating color distribution on the paper surface is one of important factor affecting the quality of coated paper produced. Viscosity of coating color is significantly influenced the uniformity of its distribution on the paper surface. The lower the viscosity, the higher the uniformity of coating color distribution. The use of native starch as viscosity control additive in coating color has limitations. It causes high viscosity in coating color. The use of enzymatic modified starch as additive of coating color have been investigated.These study were conducted in several steps. Step I was base papermaking using 80% LBKP and 20 % NBKP after refining separately up to 315 ml CSF. Then, 15% CaCO3, 0,6% AKD, 0,5% poliacrylamide, and 1,5% cationic starch base on dry-weight of fibers was added to the fiber mixture. Step II was modification of starch enzymaticaly at 70-75°C, pH 6,5 - 7,0, 0,05% amylase, for 15 minutes. Step III was base-paper coating process using native starch (variation I), enzymatic modified starch (variation II), and commercial starch (variation III) of 8% each. The handsheets were tested for brightness, roughtness, picking strength, Cobb size, and pH. The results showed that the viscosity of native starch, enzymatic modified starch and commercial starch were 8000 cPs, 26 cPs and 114 cPs respectively. The use of enzymatic modified starch gave the best paper properties. The similar results were showed for the experiments conducted in the paper industry’s laboratory using the mixture of clay and CaCO3 at 40:60 ratio, and the same enzymatic modified starch, commercial starch, and native starch. Keywords : starch, coated printing paper, amylase, viscosity. DOI: 10.7176/CMR/11-9-04 Publication date: November 30th 201