The present invention relates to a new process for improving runnability and dimensional stability when manufacturing a film comprising high amounts of microfibrillated cellulose (MFC) without negatively impacting the film properties. According to the present invention a high amount of nanoparticles is used as an additive, optionally together with a retention polymer.

A treated article includes fibers, a sizing agent, and a retention aid. The sizing agent includes a wax or a component thereof having an acid value of from 10 mg to 220 mg, KOH/g as measured in accordance with USP 401. The retention aid includes a nitrogen-containing polymer independently selected from the group consisting of (i) a nitrogen-containing polymer of Formula I, (ii) a polyethyleneimine, (iii) a polyaminoamide, (iv) a copolymer formed from the reaction product of epichlorohydrin and dimethylamine, and (v) combinations thereof.

A treated article includes fibers, a sizing agent, and a retention aid. The sizing agent includes a wax or a component thereof having an acid value of from 10 mg to 220 mg, KOH/g as measured in accordance with USP 401. The retention aid includes a nitrogen-containing polymer independently selected from the group consisting of (i) a nitrogen-containing polymer of Formula I, (ii) a polyethyleneimine, (iii) a polyaminoamide, (iv) a copolymer formed from the reaction product of epichlorohydrin and dimethylamine, and (v) combinations thereof.

A method of and an arrangement for adding a chemical to an approach flow system of a fiber web machine by mixing of a retention chemical to a fibrous stock flowing in an approach flow system of a fiber web machine by a mixer (200) between the attenuator (16) and the headbox (18).

A method of and an arrangement for adding a chemical to an approach flow system of a fiber web machine by mixing of a retention chemical to a fibrous stock flowing in an approach flow system of a fiber web machine by a mixer (200) between the attenuator (16) and the headbox (18).

A method for manufacturing paper or board is disclosed and further disclosed is an internal sizing system for providing improved retention of hydrophobic internal sizing agents. The internal sizing system includes a hydrophobic internal sizing agent as a first component selected from a group consisting of alkenyl succinic anhydride (ASA), alkyl ketene dimer (AKD), rosin sizes and any combination thereof, and a water-soluble polymer product including amphoteric polyacrylamide as a second component, which amphoteric polyacrylamide has neutral or cationic net charge at pH 7, a weight-average molecular weight of 700,000-18,000,000 g/mol and a total ionicity of 4-28 mol-%, where the first component and the second component are provided as separate components or as a combination of the first component and the second component.

A method for manufacturing paper or board is disclosed and further disclosed is an internal sizing system for providing improved retention of hydrophobic internal sizing agents. The internal sizing system includes a hydrophobic internal sizing agent as a first component selected from a group consisting of alkenyl succinic anhydride (ASA), alkyl ketene dimer (AKD), rosin sizes and any combination thereof, and a water-soluble polymer product including amphoteric polyacrylamide as a second component, which amphoteric polyacrylamide has neutral or cationic net charge at pH 7, a weight-average molecular weight of 700,000-18,000,000 g/mol and a total ionicity of 4-28 mol-%, where the first component and the second component are provided as separate components or as a combination of the first component and the second component.

The present invention is directed to products, such as paper and paperboard products, comprising a substrate containing cellulose and top ply comprising microfibrillated cellulose and inorganic particulate, to methods of making such paper and paperboard products, and associated uses of such paper and paperboard products. The microfibrillated cellulose and inorganic particulate material are applied at the stage when the wet substrate is in the process of being formed on the wire of a papermaking machine, thereby avoiding the additional cost of more extensive equipment and machinery as well as in separate drying of a coating. The microfibrillated cellulose facilitates the application of inorganic particulate onto the surface of a wet paper or paperboard substrate when applied thusly, by trapping the inorganic particulate on the surface of the substrate and by giving the composite sufficient strength and a suitable pore structure to make it suitable for printing and other end-use demands.

The present invention is directed to products, such as paper and paperboard products, comprising a substrate containing cellulose and top ply comprising microfibrillated cellulose and inorganic particulate, to methods of making such paper and paperboard products, and associated uses of such paper and paperboard products. The microfibrillated cellulose and inorganic particulate material are applied at the stage when the wet substrate is in the process of being formed on the wire of a papermaking machine, thereby avoiding the additional cost of more extensive equipment and machinery as well as in separate drying of a coating. The microfibrillated cellulose facilitates the application of inorganic particulate onto the surface of a wet paper or paperboard substrate when applied thusly, by trapping the inorganic particulate on the surface of the substrate and by giving the composite sufficient strength and a suitable pore structure to make it suitable for printing and other end-use demands.

There is provided an ethyleneimine polymer (solution) capable of expressing excellent properties when used in such usages as, for example, coagulants for wastewater, papermaking chemicals such as freeness improvers and the like, enzyme immobilization agents, and adhesion improvers (for example, adhesion promoters for extrusion laminate (anchor coating agent)). To solve the above object, there is provided an ethyleneimine polymer solution including an ethyleneimine polymer and water, wherein a weight average molecular weight (Mw) of the ethyleneimine polymer is 200,000 or more, the weight average molecular weight (Mw) being measured based on pullulan by gel permeation chromatography (GPC), and a ratio of a component having a weight average molecular weight (Mw) of 30,000 or more is 60 mass % or more with respect to 100 mass % of a total amount of the ethyleneimine polymer.