This invention relates to a method for manufacturing a sheet of paper or cardboard, according to which, before forming said sheet, at least one N-vinylformamide polymer that is partially hydrolyzed in the form of an inverse emulsion is added, at one or more injection points, to a fibrous suspension in the presence of an anti-gelling agent, and having a cationic regain between 30 and 150%, the inverse emulsion having a weight ratio of partially hydrolyzed N-vinylformamide polymer to anti-gelling agent in the range between 1,000,000/5000 and 1,000,000/50,000.

Disclosed is method for on-site glyoxylation of polyacrylamide in a paper or board mill, where a discontinuous batch glyoxylation reaction of aqueous reaction mixture is performed in reactor vessel having driven agitator to form aqueous polymer composition comprising glyoxylated polyacrylamide. The method comprises forming or obtaining the aqueous reaction mixture comprising polyacrylamide base polymer and glyoxal, determining alkali consumption of the mixture, and adding to the mixture, based on determined alkali consumption, pre-determined amount of alkali for adjusting pH to 8-10. The temperature is optionally adjusted to 15-40° C. and the on-site glyoxylation reaction of polyacrylamide base polymer is allowed to proceed. Viscosity of the mixture and/or a variable related to the viscosity is measured, acid is added to the mixture for lowering pH to <8, when a predetermined end viscosity value is attained, and the aqueous polymer composition comprising glyoxylated polyacrylamide is removed from the reaction vessel.

A method of reducing contaminants in a pulp or papermaking process includes the steps of: providing a lignocellulosic pulp comprising lignocellulosic fibers and at least one hydrophobic contaminant; providing a cationic polymer; providing a cleaning blend comprising a vegetable oil alkyl ester and at least one surfactant; and applying the cationic polymer and the cleaning blend to the lignocellulosic pulp to reduce a content of the at least one hydrophobic contaminant in the pulp or papermaking process.

A method of reducing contaminants in a pulp or papermaking process includes the steps of: providing a lignocellulosic pulp comprising lignocellulosic fibers and at least one hydrophobic contaminant; providing a cationic polymer; providing a cleaning blend comprising a vegetable oil alkyl ester and at least one surfactant; and applying the cationic polymer and the cleaning blend to the lignocellulosic pulp to reduce a content of the at least one hydrophobic contaminant in the pulp or papermaking process.

The invention relates to a composition and method for manufacture of paper, board, tissue or the like. The composition comprises an amphoteric polymer component, which has a weight average molecular weight of at least 600 000 g/mol, preferably at least 1 000 000 g/mol, more preferably at least 2 000 000 g/mol, and at least one synthetic cationic polymer component, which is a copolymer of a polyamidoamine and has a weight average molecular weight ≤550 000 g/mol, preferably ≤500 000 g/mol, more preferably ≤400 000 g/mol and dispersity index more than 15, preferably more than 20, more preferably more than 25.

The invention relates to a composition and method for manufacture of paper, board, tissue or the like. The composition comprises an amphoteric polymer component, which has a weight average molecular weight of at least 600 000 g/mol, preferably at least 1 000 000 g/mol, more preferably at least 2 000 000 g/mol, and at least one synthetic cationic polymer component, which is a copolymer of a polyamidoamine and has a weight average molecular weight ≤550 000 g/mol, preferably ≤500 000 g/mol, more preferably ≤400 000 g/mol and dispersity index more than 15, preferably more than 20, more preferably more than 25.

The present disclosure generally relates to glyoxalated polyacrylamide (GPAM) compositions, methods of preparation and methods of use thereof, particularly in the paper industry. Moreover, the present disclosure generally pertains to cationic GPAM compositions, methods of preparation and methods of use thereof in papermaking applications and in products such as paper-based products, wherein the cationic GPAM compositions may provide increased wet and/or dry strength to the paper-based products, and wherein such cationic GPAM compositions optionally require a reduced volume of an aqueous carrier for storage or transport compared to a volume of an aqueous carrier needed for conventional GPAMs used in papermaking.

A papermaking agent exhibiting an excellent freeness and paper strength effect with little increase in viscosity after long-term storage. A papermaking agent including a (meth)acrylamide polymer containing two or more starches (a1) selected from the group consisting of unmodified starch, oxidized starch, esterified starch, etherified starch, amidated starch, cationic starch, amphoteric starch and crosslinked starch, a (meth)acrylamide (a2), a polymerizable monomer having an amino group (a3), a polymerizable monomer having a carboxy group (a4) and a polymerizable monomer having a sulfonate group (a5) as essential constituent components.

A process for producing paper or board, which process comprises ad-mixing (I) an aqueous composition of pH ≦6 and (II) at least one water-soluble polymeric anionic compound to a paper stock having a pH in the range from 6 to 8 and then dewatering the paper stock by sheet formation and drying, wherein the aqueous composition comprises (a) polymers having primary amino groups and/or amidine groups to a combined content for these groups of ≧1.5 meq/g of polymer, and (b) 0.01 to 50 mol % of 1,4-cyclohexanedione (b) based on the combined amount of primary amino groups and/or amidine groups of the polymers, and also to the paper or board thus obtained.

A method for obtaining a fibrous preparation for manufacturing a paper having significant water repellency and opacity in the dry or wet state. Fibres are suspended in water; calcium salts are added to the fibres; a source of carbonate salts in the form of an aqueous solution are added and the resulting mixture is stirred for a time sufficient to allow calcium carbonate particles to be precipitated. A solution of fatty acid salts heated to a temperature which corresponds to the micellisation temperature of said fatty acid salts is added and takes into account the critical micellar concentration of the fatty acid salts. The mixture is stirred thus obtained for a time sufficient to allow the fatty acids to be absorbed at the surface of the calcium carbonate particles and to obtain the desired fibrous preparation.