| Cultural paper and printing paper is heading the low basis weight and lighter trend, but one of the core problems is the opacity. Carbon dioxide could react with Ca(OH)2 solution, which modifies fiber with nano-calcium carbonate film on its surface, this modified fiber obtains optical quality that ordinary calcium carbonate has, what is more is that its consistency is close to fiber. Using this new material to make paper with plain fiber instead of calcium carbonate, this dissertation analyzes its effect on paper's opacity.The result of the research reveals that under following reaction draft: reaction temperature is 10℃, concentration of fiber is 2%, concentration of Ca(OH)2 is 2%, stirring speed is 600rpm, flow rate of CO2 is 80l/h and diameter of gas distributor is 2.0mm, the experiment produces nano-calcium carbonate modifying paper which put on weight 60% than unmodified fiber. And this experiment stimulates the shear force of white water by using dynamic draining jar. Set stirring speed is 1500rpm, shearing time is 60s, under such circumstance almost 59% calcium carbonate particles will resist this kind of force, still retain on the surface of the fiber.To make usual cultural paper(basis weight is 60g/m2) with regular pulp, the ratio of modified fiber to whole paper sheet is 1 to 10, the whiteness is 87.16, opacity is 84.92%, tightness is 0.383g/cm3, tearing index is 10.6 mN·m2/g, burst strength is 2.2Kgf/cm2. Compared with traditional adding 20% PCC to the paper, the opacity, whiteness, tightness, burst strength of paper sheet filled with modified fiber are reaching the same level, and tearing index and tensile strength are both increase some degree, separately 54% and 26%.This paper also analyzes the particle characteristic of dissociative calcium carbonate produced by modifying reaction. The Dn reaches 1μm, and 90% calcium carbonate's diameter is within 2.5μm, it belongs to macro-CaCO3 category (15μm), partial particle has reached superfine CaCO3 category (0.11μm).
|
PDF Full Text Request