Abstract: Method for the production of mechanical or chemi-mechanical pulp as raw material for paper or cardboard. According to this method, the pulp is fibrillated and the fibrillated pulp is bleached in alkaline conditions. According to the present invention, the pulp is screened to separate the reject from the accept, at maximum approximately 60% of the total amount of pulp is separated as the reject, the reject is bleached separate from the accept, and, after that, the bleached reject is remixed with the accept. When operating according to the present invention, the strength of the pulp increases and the energy used for refining is reduced, which is seen both in the refining of the reject and in the post-refining of the final mechanical pulp.

Abstract: Method for the production of mechanical or chemi-mechanical pulp as raw material for paper or cardboard. According to this method, the pulp is fibrillated and the fibrillated pulp is bleached in alkaline conditions. According to the present invention, the pulp is screened to separate the reject from the accept, at maximum approximately 60% of the total amount of pulp is separated as the reject, the reject is bleached separate from the accept, and, after that, the bleached reject is remixed with the accept. When operating according to the present invention, the strength of the pulp increases and the energy used for refining is reduced, which is seen both in the refining of the reject and in the post-refining of the final mechanical pulp.

Abstract: A filler comprising cellulose or lignocellulose fibrils on which light-scattering material particles have been deposited, and a process for the manufacture thereof. In the filler according to the invention, an alkyl derivative of cellulose, such as CMC, has been sorbed to the fibrils. Such a filler can be prepared from a source material containing cellulose or lignocellulose fibrils by first forming a fibril suspension, into which there are fed source materials forming an inorganic or organic salt that, when precipitating, forms a light-scattering pigment. The filler according to the invention has very good strength properties; in particular, good bond strength is achieved by means of it. The concentration of mineral pigment in paper can be increased and, furthermore, the grammage of paper can be lowered without the other important properties of the paper deteriorating.

Abstract: The present invention relates to a method for coating of a fibrous web. According to the method a coating color with pigments is applied to the surface of the web and dried in order to form a coated web. The invention comprises using a coating color which contains pigments having a steep particle size distribution, a maximum of 35% of the pigment particles being smaller than 0.5 &mgr;m. The coating color is spread on the surface of the web with a coating speed of at least 1450 m/min, preferably over 1600 m/min. The coating pigment having a steep particle size distribution gives rise to a coating color which solidifies at much lower dry substance than conventional coating colors. In this way coating can be controlled at high speed without runnability and quality problems.

Abstract: A filler comprising cellulose or lignocellulose fibrils on which light-scattering material particles have been deposited, and a process for the manufacture thereof. In the filler according to the invention, an alkyl derivative of cellulose, such as CMC, has been sorbed to the fibrils. Such a filler can be prepared from a source material containing cellulose or lignocellulose fibrils by first forming a fibril suspension, into which there are fed source materials forming an inorganic or organic salt that, when precipitating, forms a light-scattering pigment. The filler according to the invention has very good strength properties; in particular, good bond strength is achieved by means of it. The concentration of mineral pigment in paper can be increased and, furthermore, the grammage of paper can be lowered without the other important properties of the paper deteriorating.

Abstract: The present invention relates to a method for coating of a fibrous web. According to the method a coating color with pigments is applied to the surface of the web and dried in order to form a coated web. The invention comprises using a coating color which contains pigments having a steep particle size distribution, a maximum of 35% of the pigment particles being smaller than 0.5 &mgr;m. The coating color is spread on the surface of the web with a coating speed of at least 1450 m/min, preferably over 1600 m/min. The coating pigment having a steep particle size distribution gives rise to a coating color which solidifies at much lower dry substance than conventional coating colors. In this way coating can be controlled at high speed without runnability and quality problems.

Abstract: The present invention concerns a process for preparing a paper web. According to the process a pulp is formed from a fibrous raw material, a web is formed from the pulp and it is dried on a paper machine. According to the invention the pulp is formed from a mechanical pulp produced from a peroxide bleached mechanical wood raw material of the genus Populus, the pH of proportioning of the mechanical pulp being set at 6.8 to 7.2 and the machine pH at 7.1 to 7.5 and the conductivity of the pulp being set at 1000 to 1500 &mgr;S/cm. By using a relatively low pH value and a narrow pH range it is possible to diminish the sensitivity to disturbances of the paper making process. According to the present invention a mechanical aspen pulp can be combined with chemical pulp for preparing base paper of fine paper, whereby the mechanical pulp gives a high conductivity on the machine which improves the stability of the wet end and enhances water removal.

Abstract: The present invention concerns a method for producing a base paper for fine papers, the base paper being produced from a mixture of a mechanical pulp and a chemical pulp. The chemical pulp used comprises a chemical softwood pulp having a elastic modulus close to that of the mechanical pulp and a great bonding strength. It is preferred to use a chemical softwood pulp which produces a sheet having a elastic modulus of less than 6000 N/mm2 when the bonding strength is 400 J/m2. A pulp of this kind has a good ScottBond strength at the same light scattering. The base paper produced by the method can therefore be used in double-coated fine papers which require a large bonding strength of the base paper.

Abstract: The invention concerns a method for producing a paper web. According to the method a stock is produced from the fibrous raw material and the stock is formed to a web which is dried on a paper machine. According to the invention the stock is formed from a mechanical pulp prepared from wood material of the Populus family and from bleached chemical spruce pulp, whereby the amount of the mechanical pulp is 20 to 70 weight-% and the amount of the bleached chemical softwood pulp is 80 to 30 weight-% of the dry matter of the stock. It is preferred to use an aspen pulp, over 70% of the fiber fractions of which comprise fiber fractions +100, +200 and −200, and the proportion of the −200 fraction is 45% or less. A coated fine paper can be produced from the paper web whose properties are better than those of a traditional fine paper having the corresponding bulk and grammage, on the same capacity level the paper produced by the invention will give a yield gain of up to more than 20%.

Abstract: The present invention concerns a method for producing a base paper for fine papers, the base paper being produced from a mixture of a mechanical pulp and a chemical pulp. The chemical pulp used comprises a chemical softwood pulp having a elastic modulus close to that of the mechanical pulp and a great bonding strength. It is preferred to use a chemical softwood pulp which produces a sheet having a elastic modulus of less than 6000 N/mm2 when the bonding strength is 400 J/m2. A pulp of this kind has a good ScottBond strength at the same light scattering. The base paper produced by the method can therefore be used in double-coated fine papers which require a large bonding strength of the base paper.