According to the invention, in producing coloured cardboard, carbon dioxide is injected and dissolved in a mixture of pulp and at least a sulphur dye, while the mixture is pumped with a delivery pressure higher than 200 kPa out of a first pulp reservoir (11) towards a second pulp reservoir (12), and in such manner that the mixture is acidified by the carbon dioxide to become an acidified coloured pulp mixture (14) with a pH-value between 6.5 and 7.0. The acidified coloured pulp is injected under high pressure out of a pulp duct structure (7) into the second pulp reservoir (12) at a distance of at least 2 meter below a level (15) of the acidified coloured pulp mixture (14) in the second pulp reservoir (12). Accordingly, the invention provides a high-quality colouring of cardboard, wherein environmental problems are prevented.

According to the invention, in producing coloured cardboard, carbon dioxide is injected and dissolved in a mixture of pulp and at least a sulphur dye, while the mixture is pumped with a delivery pressure higher than 200 kPa out of a first pulp reservoir (11) towards a second pulp reservoir (12), and in such manner that the mixture is acidified by the carbon dioxide to become an acidified coloured pulp mixture (14) with a pH-value between 6.5 and 7.0. The acidified coloured pulp is injected under high pressure out of a pulp duct structure (7) into the second pulp reservoir (12) at a distance of at least 2 meter below a level (15) of the acidified coloured pulp mixture (14) in the second pulp reservoir (12). Accordingly, the invention provides a high-quality colouring of cardboard, wherein environmental problems are prevented.

A method for the production of paper products, such as paper and cardboard, by recycling cellulose-based raw materials containing starch. The method includes the steps of pulping in water cellulose-based raw materials containing starch, particularly recycled paper products, obtaining a pulped mass; adding to the pulped mass of the previous step under agitation a mineral acid in a quantity that is suitable to obtain a pH of the pulped mass not lower than 4, and obtaining a pulped mass treated with acid. The method further includes the step of subjecting the pulped mass treated with acid obtained in the second step, optionally treated with other chemical additives, in succession, to filtration, pressing and drying, and obtaining a paper product. Paper products obtainable by this method are also related.

A method for the production of paper products, such as paper and cardboard, by recycling cellulose-based raw materials containing starch. The method includes the steps of pulping in water cellulose-based raw materials containing starch, particularly recycled paper products, obtaining a pulped mass; adding to the pulped mass of the previous step under agitation a mineral acid in a quantity that is suitable to obtain a pH of the pulped mass not lower than 4, and obtaining a pulped mass treated with acid. The method further includes the step of subjecting the pulped mass treated with acid obtained in the second step, optionally treated with other chemical additives, in succession, to filtration, pressing and drying, and obtaining a paper product. Paper products obtainable by this method are also related.

A method for manufacturing paper is disclosed. A pulp slurry is produced, a paper sheet is formed from the slurry, an aldehyde functionalized polymer or polymers in combination with at least one additional strength additive is added to the slurry before and/or after sheet formation, and a water soluble acid is added on the paper sheet.

The invention relates to pretreating of native cellulose pulp in the manufacture of nanofibrillated cellulose, and to a nanofibrillated cellulose product obtainable by the method.

The invention relates to pretreating of native cellulose pulp in the manufacture of nanofibrillated cellulose, and to a nanofibrillated cellulose product obtainable by the method.

The present invention relates to thermal insulation materials, particularly to environmentally friendly thermal insulation materials, manufacturing of which involves recycled raw materials and hemp fibres. The thermal insulation material described in the invention further comprises bi-component binder and conservation additive.

The present invention relates to thermal insulation materials, particularly to environmentally friendly thermal insulation materials, manufacturing of which involves recycled raw materials and hemp fibres. The thermal insulation material described in the invention further comprises bi-component binder and conservation additive.

The invention relates to fibrous structures having desirable physical properties, such as good tensile strength, low stiffness and high bulk, manufactured using a fiber furnish comprising cellulosic fibers having a pH of 5.0 or less and at least one strength resin. Not only do structures prepared with acidic fibers have desirable physical properties, they may also be manufactured in an energy efficient manner. To achieve the greatest energy savings it is generally desirable that acidic fibers not be subjected to mechanical treatment, such as by refining, prior to forming the fiber into a fibrous structure. Further, it may be desirable to subject the remainder of the fiber furnish to a minimal degree of mechanical treatment, such as by refining, so as to produce a furnish having a freeness greater than about 550 mL.