Paper coating pigments and their production and use

  • US 5,833,747 A
  • Filed: 10/09/1996
  • Issued: 11/10/1998
  • Est. Priority Date: 10/10/1995
  • Status: Expired due to Term
First Claim
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1. A method for the preparation of a precipitated calcium carbonate (PCC) for use as a pigment in paper coating compositions, the method comprising the steps of (a) carbonating an aqueous lime-containing medium to produce an aqueous suspension containing a PCC in predominantly scalenohedral, rhombohedral, or aragonite crystal form, (b) at least partially dewatering the PCC-containing suspension;

  • and (c) subjecting the PCC-containing suspension in wet form to comminution by high shear attrition grinding with an attrition grinding mediums wherein the comminution step is carried out such as to dissipate in the aqueous suspension containing the PCC at least 100 kilowatt hours of energy per dry tonne of PCC and wherein the PCC product produced following steps (b) and (c) comprises particles having a particle size distribution such that at least 70% be weight of the particles have an equivalent spherical diameter as measured by sedimentation of less than 1 μ

    m and at least 50% by weight of the particles have an equivalent spherical diameter of less than 0.5 μ

    m.

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