PRODUCTION OF HIGH CONCENTRATION SLURRY OF SYNTHETIC CALCIUM CARBONATE HAVING GOOD FLUIDITY

摘要

PURPOSE:To prepare a high concn. slurry having good fluidity with ease, by adding a specific acrylic polymer, etc. as a dispersant to synthetic calcium carbonate, and subjecting the mixture to two stages of dispersing treatments at different shearing speeds. CONSTITUTION:Synthetic calcium carbonate of =1wt% moisture content and of a cubic shape having 0.1-1.0mum grain sizes is used. Alkali metal salt or ammonium salt of an acrylic polymer or copolymer contg. at least 90mol% acrylic acid unit of 8,000-150,000 weight average mol.wt. is used for the dispersant. Such dispersant is added as an aq. soln. prepd. by dissolving the same at 0.5- 5.0wt% ratio based on the total weight of the synthetic calcium carbonate in water of the volume of =35wt% based on the entire weight of the final mixture to the synthetic calcium carbonate. The mixture is first subjected to primary dispersing treatment at 102-103sec-1 shearing rate then to secondary sipensing treatment at 105-107sec-1, whereby the high concn. slurry of the synthetic calcium carbonate contg. =65wt% solids and having good fluidity is obtd.