Abstract: The invention relates to a method for treating a fibre stock for making of paper, board or the like. The method comprises obtaining a fibre thick stock and adding to the fibre thick stock at least one cationic first agent, and adding separately to the fibre stock and after the addition of the cationic first agent, at least one anionic second agent, which is an water-soluble anionic copolymer of acrylamide, methacrylamide or acrylonitrile, in such amount that the ratio of the added absolute cationic charge to the added absolute anionic charge is from 1:0.1 to 1:0.95. The invention relates also to the product prepared by using a fibre stock, which is treated by using the method.

Abstract: The invention relates to a papermaking agent system in liquid form, which comprises (i) cationic starch solution, prepared by cooking a starch mixture comprising a starch component and a water component, and (ii) polymer composition, which has anionic and cationic groups and a cationic net charge of >0.1 meq/g. The polymer composition comprises or originates from at least one of constituents a), b) or c). Constituent a) contains an amphoteric polymer, which is a copolymer comprising structural units derived from acrylamide and/or methacrylamide monomers, and anionic and cationic groups attached to the copolymer. Constituent b) contains a first polymer, which is a copolymer comprising structural units derived from acrylamide and/or methacrylamide monomers, and anionic or cationic groups attached to the copolymer, as well as a second polymer, which comprises groups with opposite charge than the first polymer.

Abstract: The invention relates to a method for making of paper, tissue, board or the like by using recycled fiber material as a raw material. The method comprises following steps: pulping recycled paper, board or the like in a pulper and obtaining a pulp flow comprising (i) an aqueous phase and (ii) at least recycled fibers and starch having low molecular weight, which are dispersed in the aqueous phase; adding a coagulant agent to the pulp flow or to an aqueous process flow comprising starch having low molecular weight; allowing the coagulant agent to interact with the starch having low molecular weight and optionally forming aggregates; and adding at least one flocculating agent, after the addition of the coagulant agent, to any flow, which comprises interacted coagulant agent, and forming a treated flow with starch comprising agglomerate(s); retaining at least part of the said aggregates and/or the said agglomerates to the fibers or to a web, which is formed.

Abstract: The invention relates to a method for producing paper, board or the like. In the method is obtained an aqueous filler dispersion, comprising particles of at least one first filler, the filler dispersion having a floc size distribution with original mean chord length value. The particles of the first mineral filler are brought into a contact with a cationic pre-treatment agent, which is capable of initiating flocculation of the filler particles in the dispersion, whereby a pre-treated filler dispersion comprising flocs, which comprise first mineral particles, is formed. The pre-treated filler dispersion is combined with a stock of fibers. The floc size distribution of the filler dispersion is changed with the pre-treatment agent, which is a natural and/or synthetic polymer, so that the mean chord length value increases at least with 2% from the original mean chord length value.

Abstract: The invention relates to a method for making of paper, tissue, board or the like by using recycled fibre material as a raw material. The method comprises following steps: pulping recycled paper, board or the like in a pulper and obtaining a pulp flow comprising (i) an aqueous phase and (ii) at least recycled fibres and starch having low molecular weight, which are dispersed in the aqueous phase; adding a coagulant agent to the pulp flow or to an aqueous process flow comprising starch having low molecular weight; allowing the coagulant agent to interact with the starch having low molecular weight and optionally forming aggregates; and adding at least one flocculating agent, after the addition of the coagulant agent, to any flow, which comprises interacted coagulant agent, and forming a treated flow with starch comprising agglomerate(s); retaining at least part of the said aggregates and/or the said agglomerates to the fibres or to a web, which is formed.

Abstract: The present invention relates to a fixative composition and process for reducing hydrophobic and/or anionic substances in fiber-containing stock for making of paper, board or the like. The composition comprises a synthetic cationic polymer, which has a charge density of 3.0-24 meq/g, and a cationic non-degraded starch, which has charge density of 0.5-3.0 meq/g. The invention relates also to thick stock composition comprising fibers and a fixative composition according to the invention.

Abstract: The invention relates to a method for producing paper, board or the like. In the method is obtained an aqueous filler dispersion, comprising particles of at least one first filler, the filler dispersion having a floc size distribution with original mean chord length value. The particles of the first mineral filler are brought into a contact with a cationic pre-treatment agent, which is capable of initiating flocculation of the filler particles in the dispersion, whereby a pre-treated filler dispersion comprising flocs, which comprise first mineral particles, is formed. The pre-treated filler dispersion is combined ed with a stock of fibres. The floc size distribution of the filler dispersion is changed with the pre-treatment agent, which is a natural and/or synthetic polymer, so that the mean chord length value increases at least with 2% from the original mean chord length value.

Abstract: The present invention relates to a device, system and method to measure tackiness of a substance, such as pulp, with an on-line or an in-line sensor having a transparent plate with a surface where tacky particles can attach. Attached particles are identified by a camera behind the plate. The camera is focused to detect stationary particles attached to the surface. Measurement is performed directly from a process stream or from a sidesteam and the plate does not need to be removed from the process for the measurement. The plate material may be plastic, such as polycarbonate or acrylic. Additionally, the flow speed may be kept be low, e.g. <0.1 m/s at the measurement position, and/or there may be a stagnation point of flow at or near measurement where the flow speed approaches zero.

Abstract: The present invention relates to a fixative composition and process for reducing hydrophobic and/or anionic substances in fibre-containing stock for making of paper, board or the like. The composition comprises a synthetic cationic polymer, which has a charge density of 3.0-24 meq/g, and a cationic non-degraded starch, which has charge density of 0.5-3.0 meq/g. The invention relates also to thick stock composition comprising fibres and a fixative composition according to the invention.

Abstract: The invention relates to a method for improving papermaking or board making process. The method comprises forming a fibre stock, and leading the fibre stock to a headbox and feeding it to a wire to form a wet fibrous web. A at least one polysaccharide having 1,4-?-anomeric configuration in linkages between saccharide units of the polysaccharide backbone or the main polysaccharide backbone is applied to the fibre stock after machine chest or on the wet fibrous web. The invention relates also to paper made by the method and to the use of polysaccharide.

Abstract: A method and arrangement for controlling short circulation in a paper machine, in which the control of at least one property of the diluted fiber-containing pulp conducted to the headbox is based on consistency measurement or determination in high-consistency fiber-containing pulp, diluted pulp and/or white water. The amount of fiber-based fines in high-consistency fiber-based pulp, diluted fiber-based pulp and/or white water is determined, and the result obtained is used for controlling at least one property of the fiber-containing pulp to be conveyed to the headbox.

Abstract: An apparatus in the treatment of stock passed to a headbox of a paper machine or equivalent includes at least two stock chests (10a1, 10a2). Stock (M1) from a first stock chest (10a1) is passed along a line (a1, a2) to a hydrococyclone plant (20) in the short circulation of the paper machine or equivalent. An accept line (a3) of the hydrocyclone plant is connected with a stock line (b1) of the stock (M2) fed from a second stock chest (10a2), and a combined stock flow is passed along a line (b2) to the headbox (100) of the paper machine or equivalent. A method in the treatment of the stock passed to a headbox of a paper machine or equivalent is disclosed.

Abstract: A method for manufacturing a layered paper or board web, in which method thick stock (M) delivered to the paper machine is diluted with tail water and the diluted stock (M1) is fractioned in order to produce two different stock fractions (A,B). The first stock fraction (A), with finer material, is conducted into the surface layer or layers of the web, and the second stock fraction (B), containing coarser material, is conducted into the middle layer or layers of the web. Before feeding into a headbox (15), the coarse stock fraction (B) is diluted with water whose consistency is substantially lower than the consistency of the water added into the thick stock (M) before fractionating. When water containing less solids than the normal tail water dilutes the coarse stock fraction, the stock fractions used for different web layers can better maintain their different properties, which improves the result of layering.

Abstract: An apparatus in the treatment of stock passed to a headbox of a paper machine or equivalent includes at least two stock chests (10a1, 10a2). Stock (M1) from a first stock chest (10a1) is passed along a line (a1, a2) to a hydrococyclone plant (20) in the short circulation of the paper machine or equivalent. An accept line (a3) of the hydrocyclone plant is connected with a stock line (b1) of the stock (M2) fed from a second stock chest (10a2), and a combined stock flow is passed along a line (b2) to the headbox (100) of the paper machine or equivalent. A method in the treatment of the stock passed to a headbox of a paper machine or equivalent is disclosed.

Abstract: The invention relates to a method and a mixer for mixing flows of a papermaking process. In the invention, a first flow is conveyed through a tube, and turbulence is generated in it by means of form parts located on the inner periphery of the tube. The mixing zone of the mixer comprises feed openings on the inner periphery of the tube for feeding a second flow from a feed channel outside the tube into the first flow, whereby the flows are mixed as a result of the turbulence generated by the form parts. According to a preferred embodiment of the invention, at least one form part comprises a feed opening.

Abstract: A method and arrangement for controlling short circulation in a paper machine, in which the control of at least one property of the diluted fiber-containing pulp conducted to the headbox is based on consistency measurement or determination in high-consistency fiber-containing pulp, diluted pulp and/or white water. The amount of fiber-based fines in high-consistency fiber-based pulp, diluted fiber-based pulp and/or white water is determined, and the result obtained is used for controlling at least one property of the fiber-containing pulp to be conveyed to the headbox.

Abstract: A method and arrangement for controlling short circulation in a paper machine, in which the control of at least one property of the diluted fiber-containing pulp conducted to the headbox is based on consistency measurement or determination in high-consistency fiber-containing pulp, diluted pulp and/or white water. The amount of fiber-based fines in high-consistency fiber-based pulp, diluted fiber-based pulp and/or white water is determined, and the result obtained is used for controlling at least one property of the fiber-containing pulp to be conveyed to the headbox.

Abstract: A process arrangement in the short circulation of a paper machine comprises a feed pump (10), a headbox (11), means (12) for passing a pulp suspension jet (J) in a closed space from the headbox (11) into a forming gap defined by two wires (13, 14), dewatering elements (15, 16) placed against the wires (13, 14) a dilution duct (17) for passing wire water from the dewatering elements (15, 16) to stock dilution, and an outlet duct (18) for passing excess wire water out of the short circulation. The dilution duct (17) and the outlet duct (18) are in flow communication, and the outlet duct (18) has means (19, 22) for keeping the pressure in the dilution duct (17) even. For controlling the pressure in the short circulation of a closed former, excess wire water is passed out through a tank (19) provided with an overflow or other control.

Abstract: A vacuum pump (P0) provides vacuum to a paper machine deaeration tank (11) which has an inlet duct (10) through which the tank is supplied with wire water. A discharge duct (12) extends from the deaeration tank (11). There is an overflow (14) for the wire water in the discharge duct at the discharge end of the discharge duct (12). The overflow (14) of the discharge duct (12) is located below the deaeration tank (11) and opens to a free air space. The discharge duct (12) includes a branch duct (15a1) for a flow which is passed to the headbox (100).

Abstract: The invention relates to a headbox of a paper machine or equivalent. The headbox comprises in its connection cleaning tubes (11a1, 11a2 . . . ), by means of which stock is separated into accept and reject, the accept being passed forward in the headbox and further onto a forming wire (H1).