Abstract: A coating color comprising 28-51% by weight of water, 43-64% by weight of carbonate-containing pigment with a specific particle distribution and a particle diameter of 0.18-0.28 .mu.m and a specific surface area of 19-26 M.sup.2 /g and 6-8% by weight of conventional binding agents and additives may be employed with advantage for coated papers. The coating color is produced by wet milling of the carbonate-containing pigment without the addition of dispersing or wetting agents at a solids concentration of 30-20% by weight in an agitating ball mill, subsequent concentration, re-dispersal and the addition of binding agents, water and additives.

Abstract: A new pigment mixture consisting of 40-80% by weight calcium carbonate and/or dolomite and 20-60% by weight talc or 20-60% of a talc-kaolin mixture or 20-60% by weight of a talc-mica mixture gives substantial improvements in the use in the paper industry, in particular in the production of lightweight coated rotogravure papers.

Abstract: An aqueous suspension of minerals and/or fillers and/or pigments having a solid content .gtoreq.60% by weight, the mineral or the filler or the pigment being dispersed with one or more dispersing agents, is characterized in that the dispersing agent contains one or more amphoteric polyelectrolytes and/or cationic polyelectrolytes and/or amphoteric cationoic polyelectrolytes and/or amphoteric anionic polyelectrolytes and/or partially neutralized anionic polyelectrolytes and/or partially neutralized amphoteric anionic polyelectrolytes, the filler and/or pigment and/or mineral particles carrying a charge neutral or positive to the outside.Furthermore is disclosed a process characterized in that a part of the polyelectrolytes according to the invention is added before the grinding, a part thereof may be added during the grinding and a part thereof may be added after the grinding. According to the invention grinding and dispersing is achieved in only one process step.

Abstract: In a method for processing granulate and/or pulverulent polymer with pulverulent additives in an injection moulding machine having a screw with a feed zone of constant screw core diameter, and intermediate zone with a compression and metering section and a mixing element array, with regard to particularly economic processing to high quality injection mouldings the polymer and the pulverulent additives are introduced without previous preparation directly into the feed zone of the screw and in the feed zone the polymer is thoroughly mixed with the pulverulent additives at least twice by means of mixing element arrays, the working length of the screw for the processing having at least 19 times the screw diameter.

Abstract: Carbonate-containing mineral fillers, pigments and similar materials are disclosed which are characterized by a combination of four features. These carbonate-containing materials can be used in particular in dyes, paints, paper pulps, paper coatings and plastics to great advantage. In addition, a method of preparing these carbonate-containing materials is disclosed.

Abstract: A material especially adapted for incorporation in a coating composition, for example, as a secondary pigment, and characterized in having corrosion inhibiting properties. The material consists of finely particulate material on which is coated a film of fatty amine or fatty amine salt. The material coated on the particles is characterized in having a high area to volume ratio and the properties thereof in respect of inhibiting corrosion are thereby enhanced. The particulate material is advantageously natural crystalline calcium carbonate.

Abstract: Mineral filler surface treated with a mixture of saturated and unsaturated aliphatic acids, and use thereof.

Abstract: A method and apparatus for determining the reflective characteristic of surfaces, especially coated surfaces, in which a beam of parallel light rays are directed against the surface at a predetermined angle of incidence. The light rays reflecting from the surface at an angle numerically equal to the angle of incidence are caused to converge and are supplied to a receiver which may be in the form of a light sensitive resistor. The light which scatters from the surface by reflecting therefrom at angles numerically different from the angle of incidence are, at least in part, collected and caused to converge and are supplied to a second receiver which may also be in the form of a light sensitive resistor. The changes in values of the resistors when illuminated in the aforesaid manner are compared and thereby a comparison is arrived at of how much light is reflected directly from the surface and how much light is scattered during reflecting.

Abstract: A varnish or paint containing ultrafine natural calcium carbonate as a filler, the carbonate having an average statistical particle diameter of from 0.5 to 0.7 .mu. and a maximum diameter of from 3 to 4 .mu..

Abstract: Filled polymer containing natural calcium carbonate having a statistical particle diameter of from 0.5 to 0.7 micron and average maximum diameter of from 3 to 4 microns.

Abstract: A coated paper comprising an ultrafine natural calcium carbonate as a pigment, which has an average statistical particle diameter of from 0.5 to 0.7 .mu.m, a maximum diameter of from 3.0 to 4.0 .mu.m, and a specific surface area of at least 12sq.m./g.

Abstract: A process is disclosed for the wet grinding of a material such as chalk comprising the steps of preparing a suspension containing material particles no coarser than 43 microns and grinding the material in suspension using grinding bodies having a density of at least 3.7 g/cc, wherein the weight ratio of the grinding bodies to the material is at least 6:1. Specific types of grinding bodies are also disclosed.