Process for manufacturing paper and board

Abstract

The present invention relates to a fibre product that contains pulp fibre or wood fibre, wherein filler particles are attached between the fibres and to the fibrils, part of the particles consisting of chemically structured kaolin agglomerates or granules, and a part consisting of carbonate that is formed from a corresponding oxide or hydroxide by means of carbon dioxide. The invention also relates to a manufacturing method of such a fibre product.

What is claimed is: 
     
         1 . A fibre product that contains pulp fibre or wood fibre, wherein filler particles are attached between the fibres and to the fibrils, part of them consisting of chemically structured kaolin agglomerates or granules, and part consisting of carbonate. 
     
     
         2 . The product according to  claim 1 , wherein there is provided a binder between the fibres, between the fibres and filler particles, as well as between the fibrils of the fibres and the filler particles, which binder preferably is latex, silicon dioxide, soluble aluminium or aldehyde or a mixture thereof, preferably in an amount of 0.05-20% by weight. 
     
     
         3 . The product according to  claim 1 , with structured kaolin particles up to 25% by weight of the fibre, preferably at least 5% by weight of the fibre. 
     
     
         4 . The product according to  claim 1 , wherein the structured particles have an essentially spherical shape and a size of >5 μm, preferably 10-40 μm, more preferably 20-40 μm. 
     
     
         5 . The product according to  claim 1 , wherein the kaolin of the structured filler is delaminated, water-washed, dry-classified, or it is treated using two or more of the said treating methods, preferably changed by heating into metakaolin or calcined kaolin at least on the outer surfaces of the particles. 
     
     
         6 . The product according to  claim 1 , wherein the salts of carbonic acid at normal pressure are carbonate or bicarbonate salts, preferably bicarbonate and colloidal carbonate, and more preferably have an average particle size of <0.3 nm, most suitably <0.1 nm. 
     
     
         7 . The product according to  claim 1 , wherein the carbonate or bicarbonate salt or a mixture thereof that is formed from a corresponding oxide or hydroxide is a precipitated inorganic or organic salt or a composite or mixture of several salts, the salt preferably being a calcium or magnesium salt or a mixture thereof. 
     
     
         8 . The product according to  claim 1 , further containing retention agents or flocculating or coagulating microparticles or a mixture thereof. 
     
     
         9 . The product according to  claim 1 , which further contains one or more chemicals known as such, which are selected from the group of aluminium compounds, stock sizes, surface sizes, colouring agents, starches, optical brighteners, plastic pigments, natural and synthetic polymers, as well as fillers and coating agents. 
     
     
         10 . A method of manufacturing a fibre product comprising:
 adding an oxide or hydroxide to an aqueous solution to form a hydroxide slurry, and reducing the pH of the solution to a range of 6.0-8.3 by conveying carbon dioxide to the solution so that the content of the salts of carbonic acid formed from the carbon dioxide and the hydroxide slurry is at least 0.01%, calculated from the total weight of the solid matter of the solution, whereby a salt composition is formed;   suspending kaolin sheets or stacks or both in water together with a binder, whereby a kaolin composition is formed;   producing kaolin drops in a spray drier from the kaolin composition, which is formed from the kaolin sheets or stacks or both and contains the binder, whereby excess water also evaporates, whereby structured kaolin particles are formed, or forming these structured kaolin particles by means of a mixing technique from the kaolin sheets or stacks or both, which are in the form of the slurry in the salt composition described above or its dissolved portion, with the binder;   admixing the formed structured kaolin particles together with the salt composition or its dissolved portion to a paper or board pulp, whereby a fibre dispersion is formed; and   precipitating the carbonate from the salt composition into particles in the dispersion while the dispersion is filtered, pressed, and dried into paper or board.   
     
     
         11 . The method according to  claim 10 , wherein the aqueous solution is raw water, chemically or mechanically purified water, wire water, filtered water that is purified to various degrees of purity, or other kind of water used in a paper factory, or a mixture thereof, preferably filtered water or process water, from which the solid matter is separated or has been separated. 
     
     
         12 . The method according to  claim 10 , wherein the used aqueous solution is chemical pulp (sulphate or sulphite pulp), mechanical or chemi-mechanical pulp, pulp manufactured with alkalis, recycled fibre, deinked fibre, nano-cellulose pulp, coated reject, uncoated reject or a mixture thereof. 
     
     
         13 . The method according to  claim 10 , wherein paper pulp is first manufactured from the aqueous solution, the solid matter of the paper pulp being mixed into the solution, whereafter the stages are carried out. 
     
     
         14 . The method according to  claim 10 , wherein the salt composition is manufactured from the carbonates or bicarbonates of magnesium or calcium, or a mixture thereof, by adding the slurry of oxide or hydroxide to the aqueous solution and conveying carbon dioxide to the solution, so that the pH in the aqueous solution remains essentially below 8.3 throughout this stage, whereby bicarbonate and colloidal carbonate are formed, their average particle size being <0.3 nm. 
     
     
         15 . The method according to  claim 10 , wherein the particles of structured kaolin are granules or agglomerates, which, at least on their outer surfaces, are converted into metakaolin or calcined kaolin by heating. 
     
     
         16 . The method according to  claim 10 , wherein binder is added to the kaolin slurry, mixing it at the same time, whereby the binder settles on the surface of the kaolin, particularly, on the surface of the structured particles that are formed from the kaolin. 
     
     
         17 . The method according to  claim 10 , wherein one or more chemicals known as such are added to the fibre dispersion, being selected from the group of aluminium compounds, stock sizes, surface sizes, colouring agents, starches, optical brighteners, plastic pigments, natural and synthetic polymers, as well as fillers and coating agents. 
     
     
         18 . The method according to  claim 10 , wherein retention agents or coagulating or flocculating microparticles or a mixture or copolymer thereof are added to the aqueous solution or fibre dispersion, in an amount of at least 0.01%, particularly about 0.01-3%, calculated from the total weight of the solid matter of the solution or dispersion. 
     
     
         19 . The product according to  claim 2 , with structured kaolin particles up to 25% by weight of the fibre, preferably at least 5% by weight of the fibre. 
     
     
         20 . The product according to  claim 2 , wherein the structured particles have an essentially spherical shape and a size of >5 μm, preferably 10-40 μm, more preferably 20-40 μm.