| 摘要 |
Preparation of an aqueous suspension of natural calcium carbonate comprises: dry or wet pre-grinding the calcium carbonate to an average diameter of 0.5-500 mu m (d 5 0) in the presence or absence of dispersants; forming an aqueous suspension of the product by adding the necessary quantity of water; simultaneously grinding the suspension in the presence of a homopolymer and/or a copolymer of methacrylic acid; and optionally concentrating, adding a dispersant and drying. Preparation of an aqueous suspension of natural calcium carbonate comprises: (a) dry or wet pre-grinding the calcium carbonate to an average diameter of 0.5-500 mu m (d 5 0) in the presence or absence of dispersants; (b) forming an aqueous suspension of the product obtained from step (a) by adding the necessary quantity of water to obtain a content of dry calcium carbonate of 10-80%, preferably 35-45%; (c) simultaneously grinding the suspension resulting from step (b) in the presence of a homopolymer and/or a copolymer of methacrylic acid having a molecular weight of 8000-15000 g/mol, preferably 12000 g/mol and a molar content of polymer chains having molecular weight of less than 3000 g/mol, of less than 20%, preferably 10%; (d) optionally concentrating the aqueous suspension obtained in step (c) to obtain a content of calcium carbonate equal to 5% above the concentration of step (b) or (c), preferably 65-75 wt.%; (e) optionally adding a dispersant to the aqueous suspension during or after step (d); and (f) optionally drying the product obtained in step (c), (d) or (e). An independent claim is included for aqueous suspension of calcium carbonate containing a homopolymer and/or a copolymer of methacrylic acid obtained by the above process. |
