Paper coating pigments, their production and use
USRE38301E1 · kind E1 · reissue
Assignee
Inventors
Key dates
| Filing date | Nov 13, 2000 |
| Grant date | Nov 11, 2003 |
| Priority date | — |
| Expiry date | Nov 13, 2020 |
Classification
- Technology area (CPC —)General
Abstract
There is disclosed 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 of a PCC predominantly in a selected crystal form, (b) at least partially dewatering the PCC-containing suspension; and (c) subjecting the PCC-containing suspension to comminution by high shear attrition grinding with an attrition grinding medium. Steps (b) and (c) may be applied in either order, ie. (b) followed by (c) or alternatively (c) followed by (b). The dewatering step (b) is preferably carried out using a pressure filter device operating at a pressure of at least 5 MPa, preferably at least 10 MPa. A pH reduction step may be applied after steps (b) and (c). Also disclosed are pigments produced by the method and pigment and paper coating compositions including such pigments.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.