Abstract: The present invention concerns a process for coating a web by applying a coating layer comprising pigment particles to the surface of the web. According to the invention, the coating layer is contacted at a preselected stage with a smooth surface, the coating layer is at least partially dried while being contacted with said surface to provide a smooth outer surface of the layer with densely packed particles, and the coating layer is separated from the smooth surface. The smooth surface of the web provided by the invention is ideal for printing or for secondary coating with polymers. Paper and board products according to the invention are easily reclaimed and can be treated in a normal pulper, because they do not contain any metal foils or polymer films.

Abstract: Apparatus and method for grinding levelling of paper, cardboard or a similar continuous web manufactured from vegetative based fibrous raw-material, said apparatus comprising a plurality of grinding means such as rolls or belts preferably arranged on both sides of the web, said means being deviated from the moving direction of the web or the web being deviated from these by means of squeeze rolls and which rolls are characterised by being trioelectrically charged with a similar electrical charge as the ground surface. The web tension can be regulated by moving the grinding means or the web from its direction of movement and the dust generated at the grinding is removed by a vacuum system.

Abstract: The present invention concerns a method for treating the surface of a fibrous web by mechanical grinding. According to the invention, the grinding is performed at substantially dry state by removing only the higher parts of the paper surface without substantially increasing the density of the web. By reducing the roughness of the surface by a maximum of 90%, the strength properties of the web remain essentially unchanged or they are even improved. Thus, when the roughness of the surface is reduced by about 40 to 60%, the tear strength increases with more that 5% in comparison to an untreated web. Papers and boards treated by the present method can be used for printing, packaging and wrapping.

Abstract: A method for coating paper, wherein a coating composition containing coating particles is applied to the surface of a paper web containing lignocellulosic fibers to produce a coated paper web having coating particles bound to the paper web, and the coated web is dried. According to the method the surface area of the interface between the paper web and the coating particles is increased in order to enhance hydrogen bonding between the coating particles and the fibers of the web. The surface area can be increased by using a coating composition comprising fine fibrous material or by abrading the surface of the paper or paperboard web or both. The invention will improve the smoothness of the surface without addition of foreign polymer binding agents to the web.

Abstract: A paper product has a base body with an upper surface and a bottom surface. A primer coating is applied in the form of a primer coating mixture to at least one of the upper and the bottom surfaces of the base body. A cover coating is applied to the primer coating. The primer coating mixture is selected from the group consisting of a first composition comprised of water, amorphous silicon dioxide, aluminum dioxide, polyvinyl alcohol, and a copolymer of butadiene/styrene and acrylonitrile, and a second composition comprised of water, a silicon compound selected from the group consisting of silicic acid and silica gel, polyvinyl alcohol, and a copolymer of butadiene-styrene and acrylonitrile.