Abstract: Bleaching a particulate calcium carbonate aqueous slurry with a reductive bleaching agent such as formamidine sulfinic acid increases the viscosity of the slurry. Combining the slurry with a metal material such as strontium hydroxide reduces any increase in viscosity of the bleached calcium carbonate slurry. Addition of the reductive bleaching agent and/or the metal material takes place prior to, during or after the manufacture of the slurry or the bleaching step. Metal materials in one embodiment include those that form substantially water insoluble precipitates of the reductive bleaching reaction products.

Abstract: A method for the treatment of kaolin particulate material comprising: providing a dispersed aqueous suspension comprising kaolin particulate material and having a pH of at least about 7.5; selecting at least one selective flocculation polymer, wherein said at least one selective flocculation polymer has a measured anionicity ranging from about 1% to about 12%, such as from about 4.5% to about 8%; selectively flocculating said suspension into a first layer and a second layer by adding to said suspension said at least one selective flocculation polymer, and separating said first layer from said second layer.

Abstract: The present invention relates to a kaolin composition having improved physical properties, for example, for use in the production of paper products. The composition can comprise kaolin having a shape factor of at least about 20. The kaolin can have a particle size distribution such that at least about 94% by weight of the kaolin can have an esd of less than about 2 ?m and/or at least about 80% by weight of the kaolin can have an esd of less than 1 ?m. The amount of the kaolin having an esd of less than about 0.25 ?m can range from about 25% to about 60% by weight. The Hercules viscosity of the kaolin product is less than 4000 rpm at 18 dynes at 63% solids and less than 1500 rpm at 18 dynes at 69% solids when measured using the “A” bob. The present invention also relates to an improved method for making the kaolin product from sedimentary kaolin.

Abstract: The present invention is a method of producing a breathable film including producing an inorganic filler by treating particles of an inorganic particulate material comprising an alkaline earth metal carbonate compound by reaction with a hydrophobizing surface treatment agent comprising one or more aliphatic carboxylic acids having at least 10 chain carbon atoms to produce a hydrophobic coating on the particles including a classification step to result in an inorganic filler having a reduced level of interfering particles. The invention is also breathable polymeric films made using the novel filler.

Abstract: Abstract of the Disclosure The present invention relates to a hydrous kaolin product having improved optical properties, for example, when used in the production of paper products. The present invention comprises an improved barrier coating for paper and a method of making the coated paper. The present invention also comprises an improved method from making filled and coated paper products. The present invention uses a composition comprising kaolin having a shape factor of at least about 70:1, such as at least about 80:1 or at least about 100:1.

Abstract: Abstract of the Disclosure A method of treating solid containing material derived from effluent or sludge from a plant for de-inking paper, the material containing calcium in the form of one or more insoluble calcium compounds, the method including the steps of treating the material with an acid to cause dissolution of the calcium thereby forming a calcium ion-containing solution in which insoluble solids are suspended, separating the solution from the insoluble solids and incinerating the separated solids. The solution containing calcium ions may be treated by adding one or more reagents to form a calcium compound precipitate, eg calcium carbonate. The particulate solids produced following the incineration step and following the precipitate formation may be employed as pigments or fillers in paper making or paper coating.

Abstract: Abstract of the Disclosure A method of treating solid containing material derived from effluent or sludge from a plant for de-inking paper, the material containing calcium in the form of one or more insoluble calcium compounds, the method including the steps of treating the material with an acid to cause dissolution of the calcium thereby forming a calcium ion-containing solution in which insoluble solids are suspended, separating the solution from the insoluble solids and incinerating the separated solids. The solution containing calcium ions may be treated by adding one or more reagents to form a calcium compound precipitate, eg calcium carbonate. The particulate solids produced following the incineration step and following the precipitate formation may be employed as pigments or fillers in paper making or paper coating.

Abstract: The present invention relates to a high surface area product and its production from solid-containing material, such as waste effluent from a paper-treating plant. The high surface area product comprises calcium carbonate, and is useful as a coefficient of friction control filler for newsprint.

Abstract: A pigment product suitable for use in a coating composition to provide a gloss coating on paper, the pigment product comprising a processed particulate kaolin whose particles have a particle size distribution such that at least 80% by weight of the particles have an equivalent spherical diameter less than 2 &mgr;m and not less than 8%, preferably not less than 12%, by weight of the particles have an equivalent spherical diameter less than 0.25 &mgr;m and whose particles have a shape factor of at least 45, preferably at least 50.

Abstract: The present invention provides kaolin clay pigments having at least the following characteristics: Brightness (GE): at least about 89.0; Shape Factor: at least about 30; Brookfield viscosity, measured at 20 rpm and at less than or equal to about 65% solids: about 100 to about 700 centipoise; and Hercules viscosity, measured at 18 dynes and at less than or equal to about 65% solids: about 200 rpm to about 1000 rpm. Preferred kaolin sources include Brazilian kaolins, especially Rio Capim kaolins. The kaolin pigments of the present invention possess a combination of optical and physical properties, such as brightness, printability, and transfer efficiency, not previously seen in existing commercial products. They are useful, e.g., in paper filler and coating compositions, ink compositions, and printing applications, especially rotogravure printing.

Abstract: The present invention is a method of producing a breathable film including producing an inorganic filler by treating particles of an inorganic particulate material comprising an alkaline earth metal carbonate compound by reaction with a hydrophobizing surface treatment agent comprising one or more aliphatic carboxylic acids having at least 10 chain carbon atoms to produce a hydrophobic coating on the particles including a classification step to result in an inorganic filler having a reduced level of interfering particles. The invention is also breathable polymeric films made using the novel filler.

Abstract: A particulate hydrous mineral suitable for use as an opacifying pigment, filler or extender has a shape factor which is greater than S, where S is defined by Equation 1 as follows: S=(d50/0.036)+20  Equation 1; where d50 is the mean particle size of the particles of the mineral measured in microns. The particulate mineral is preferably a kaolin, which is particularly suitable for use in aqueous matt paint compositions.

Abstract: The present invention is a method of producing a breathable film including producing an inorganic filler by treating particles of an inorganic particulate material comprising an alkaline earth metal carbonate compound by reaction with a hydrophobizing surface treatment agent comprising one or more aliphatic carboxylic acids having at least 10 chain carbon atoms to produce a hydrophobic coating on the particles including a classification step to result in an inorganic filler having a reduced level of interfering particles. The invention is also breathable polymeric films made using the novel filler.

Abstract: A method of treating solid containing material derived from effluent or sludge from a plant for de-inking paper, the material containing calcium in the form of one or more insoluble calcium compounds, the method including the steps of treating the material with an acid to cause dissolution of the calcium thereby forming a calcium ion-containing solution in which insoluble solids are suspended, separating the solution from the insoluble solids and incinerating the separated solids. The solution containing calcium ions may be treated by adding one or more reagents to form a calcium compound precipitate, eg calcium carbonate. The particulate solids produced following the incineration step and following the precipitate formation may be employed as pigments or fillers in paper making or paper coating.

Abstract: The present invention relates to calcined kaolin products, their production, and use. More specifically, the invention relates to calcined kaolin-containing products having a median diameter particle size of from about 0.5 &mgr;m to about 10 &mgr;m, and a multimodal particle size distribution defined herein. The calcined kaolin products of the invention possess a combination of physical properties and applied properties not previously seen together in calcined kaolin pigments. The products according to the invention find use as flattening (or matting) agents, and as fillers or extenders in paint and coating compositions. More generally, the inventive products may be used wherever calcined kaolins are used.

Abstract: A method of producing a rheologically stable concentrated aqueous suspension of a particulate alkaline earth metal carbonate which method comprises the following steps: (a) preparing a dilute aqueous suspension of the carbonate having a solids content of not more than 40% by weight; (b) dewatering the dilute aqueous suspension to form a carbonate suspension having a solids content in the range of from 45% to 65% by weight; (c) optionally mixing with the dewatered suspension formed in step (b) a dispersing agent for the carbonate to form a fluid suspension; (d) further dewatering the fluid suspension formed in step (b) by thermal evaporation under reduced pressure to raise the solids content of the suspension by a further differential amount of at least 5% by weight; and (e) after at least some of the dewatering in step (c) treating the suspension by a mechanical working process in which at least 1 kW.hr per tonne of carbonate on a dry weight basis is dissipated to refluidise the suspension.

Abstract: A pigment product suitable for use in a coating composition to provide a gloss coating on paper, the pigment product comprising a processed particulate kaolin whose particles have a particle size distribution such that at least 80% by weight of the particles have an equivalent spherical diameter less than 2 &mgr;m and not less than 8%, preferably not less than 12%, by weight of the particles have an equivalent spherical diameter less than 0.25 &mgr;m and whose particles have a shape factor of at least 45, preferably at least 50.

Abstract: A method of treating a kaolin particulate material to improve its properties by removal of impurities which includes the steps of: (a) producing a dispersed aqueous suspension of a kaolin particulate material containing at least 0.1% by weight, based on the dry weight of the kaolin particulate material, of separable impurity by adding a dispersing agent to the kaolin particulate material to deflocculate solid particles of the material in the suspension; (b) conditioning the suspension prior to adding selective flocculation polymer thereto by allowing the suspension to age for a period of at least 30 minutes and optionally by adding one or more conditioning chemicals thereto; (c) adjusting the pH of the suspension to be at least about 9.5; (d) adding to the suspension at a pH of at least about 9.

Abstract: A pigment product suitable for use in a coating composition to provide a gloss coating on paper, the pigment product comprising a processed particulate kaolin produced from a naturally platy kaolin clay having a particle size distribution such that about 50% to 60% by weight of the particles have an esd less than 2 &mgr;m and less than 25% by weight of the particles have an esd less than 0.25 &mgr;m and a shape factor of at least 15. In processing, the crude kaolin is ground to a shape factor greater than 50 to produce even greater “platy” clay. The pigment product has a particle size distribution such that at least 80% by weight of the particles have an esd less than 2 &mgr;m and greater than 12% and less than 35% by weight of the particles have an esd less than 0.25 &mgr;m and whose surface area is greater than 12 m2/g when measured by the BET method.

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.