Abstract: This invention concerns a process for the preparation of large surface area, finely divided precipitated calcium carbonate which comprises introducing carbon dioxide into an aqueous slurry of greater than about five weight percent calcium hydroxide containing an anionic organopolyphosphonate polyelectrolyte, starting the introduction at a temperature above about 7.degree. C. and below about 18.degree. C., continuing the introduction until calcite precipitation is substantially complete and adding a quantity of polybasic acid to the slurry in an amount greater than about 0.3% by weight of the precipitated calcium carbonate. This invention also concerns said large surface area, finely divided precipitated calcium carbonate which has been coated with a fatty acid derivative and polymeric compositions which contain such coated calcium carbonate.

Abstract: This invention concerns a process for the preparation of large surface area, finely divided precipitated calcium carbonate which comprises introducing carbon dioxide into an aqueous slurry of greater than about five weight percent calcium hydroxide containing an anionic organopolyphosphonate polyelectrolyte, starting the introduction at a temperature above about 7.degree. C. and below about 18.degree. C., continuing the introduction until calcite precipitation is substantially complete and adding a quantity of polybasic acid to the slurry in an amount greater than about 0.3% by weight of the precipitated calcium carbonate. This invention also concerns said large surface area, finely divided precipitated calcium carbonate which has been coated with a fatty acid derivative and polymeric compositions which contain such coated calcium carbonate.

Abstract: The binder demand of particulate inorganic filler is reduced without essentially altering the filler's surface area by subjecting the filler alone to intense rotary impact agitation at a peripheral speed of from about 20 to 60 meters per second. Compositions comprising a binder together with a filler prepared by this method include those in which the binder comprises alkyd resin, especially an unsaturated polyester resin, epoxy resin or linseed oil and the filler comprises ground limestone, talc or hydrated alumina.