Light and smooth coating for paper or board, or a paint coating, formed using a composite structure

Abstract

The present invention relates to a coating composition that comprises a composite structure with a body of polysaccharide, into which carbonate has been precipitated. The invention also relates to a coated paper or board product, onto which the said composition has been spread on one or both sides into one or more layers; as well as to paint that is formed of the coating composition according to the invention, or that contains the said composition.

What is claimed is: 
     
         1 . A coating composition for the coating, pigmenting, or surface sizing of a paper or board product, comprising containing a composite structure with a polysaccharide body, into which carbonate has been precipitated. 
     
     
         2 . The coating composition according to  claim 1 , wherein the polysaccharide is starch, cold-soluble starch, carboxy-methyl cellulose, guar gum or nanocellulose or a mixture of any of the above, preferably starch or nanocellulose, most preferably cold-soluble starch, whereby the shape of the polysaccharide body is preferably swollen or partly or fully broken. 
     
     
         3 . The coating composition according to  claim 1 , wherein the precipitated carbonate is calcium or magnesium carbonate or a combination thereof, and at least part of the carbonate is preferably precipitated from the solution directly into the polysaccharide body. 
     
     
         4 . The coating composition according to  claim 3 , wherein part of the carbonate is added carbonate, which is preferably calcium carbonate, such as precipitated calcium carbonate (PCC) or ground calcium carbonate (GCC) or a mixture thereof. 
     
     
         5 . The coating composition according to  claim 1 , further comprising other pigments, binders, and additives, such as latex, polyvinyl alcohol, CMC, starch, kaolin, calcined kaolin, talc, titanium dioxide, composite pigments, granule pigments, protein, casein, dispersing agents, anti-foam agents, foam removers, pH regulators, hardening agents, lubricants, regulators of water retention and rheology, synthetic thickeners, lubricants, optical clarification agents, colouring agents, and/or microbicides. 
     
     
         6 . The coating composition according to  claim 1 , wherein a coating slip is having a dry matter content of at least 55%. 
     
     
         7 . The coating composition according to  claim 1 , wherein a pigmenting paste is having a dry matter content of at least 20%. 
     
     
         8 . The coating composition according to  claim 1 , wherein a surface sizing paste is having a dry matter content of at least 2%. 
     
     
         9 . Use of the coating composition according to  claim 1  as paint. 
     
     
         10 . A coated paper or board product, wherein, on one or both surfaces thereof, the composition according to  claim 1  is spread into one or more layers. 
     
     
         11 . The coated paper or board product according to  claim 10 , wherein also one or more layers of other coating, pigmenting or surface sizing pastes are spread on one or both surfaces thereof. 
     
     
         12 . The coated paper or board product according to  claim 10 , wherein the coating composition, which has been spread on its surface, has formed after the drying one or more layers of coating, pigmenting, or surface sizing, the basis weight of which is at least 0.05 g/m 2 . 
     
     
         13 . The coated paper or board product according to  claim 10 , wherein it is a surface-sized or pigmented printing paper or packing material, or a special paper grade, such as a wallpaper base or kraft paper. 
     
     
         14 . A method of manufacturing the coated paper or board product according to  claim 10 , wherein a coating composition containing a composite structure with a polysaccharide body, into which carbonate has been precipitated, is spread on one or both sides of the uncoated paper or board product into one or more layers. 
     
     
         15 . The method according to  claim 14 , wherein a contacting or non-contacting coating method is used for the spreading of the coating composition, whereby the non-contacting methods are selected from the group of curtain and spray coating, electric field-assisted coating, and dry powder coating; and the contacting methods are selected from a group of blade, rod, and air brush coating, and film transfer coating. 
     
     
         16 . The method according to  claim 14 , wherein the coating composition is prepared in an aqueous solution, and after spreading onto the paper or board product, excess water is removed by drying, preferably with hot air or infrared lamps. 
     
     
         17 . The method according to  claim 14 , wherein the coating is made without a separate intermediary rolling. 
     
     
         18 . The method according to  claim 14 , wherein the coating is made at a separate coating station after intermediary rollings. 
     
     
         19 . A method of spreading paint on a surface to be painted, wherein the coating composition according  claim 1  is mixed with optional additives and binders, whereafter the composition is spread onto the surface in wet form with a roller or by spraying or in dry form by powder painting, whereafter the coat of paint is dried.