The invention relates to a use of a water-soluble polymer product comprising amphoteric polyacrylamide, which has neutral or cationic net charge at pH 7, a weight-average molecular weight of 2,500,000-18,000,000 g/mol and a total ionicity of 4-28 mol-%. The polymer product is used for controlling deposit formation caused by hydrophobic substances in manufacture of paper or board, where a fibre web is formed from an aqueous suspension of fibres. The invention relates also to a method for controlling deposit formation caused by hydrophobic substances in manufacture of paper or board, where a fibre web is formed from an aqueous suspension of fibres, as well as to produced paper or board.

The invention relates to a use of a water-soluble polymer product comprising amphoteric polyacrylamide, which has neutral or cationic net charge at pH 7, a weight-average molecular weight of 2,500,000-18,000,000 g/mol and a total ionicity of 4-28 mol-%. The polymer product is used for controlling deposit formation caused by hydrophobic substances in manufacture of paper or board, where a fibre web is formed from an aqueous suspension of fibres. The invention relates also to a method for controlling deposit formation caused by hydrophobic substances in manufacture of paper or board, where a fibre web is formed from an aqueous suspension of fibres, as well as to produced paper or board.

Removal of stickies from waste paper and paperboard is obtained with the use of a modified kaolin-based stickies removal composition. The modified kaolin-based stickies removal composition is produced by modifying the kaolin clay, separating the modified kaolin clay from the non-reactive kaolin clay, and then adding a nonionic surfactant to the modified kaolin-based particles. Removal of stickies is improved by the use of this modified kaolin-based stickies removal composition during the recycling of the waste paper and paperboard.

Removal of stickies from waste paper and paperboard is obtained with the use of a modified kaolin-based stickies removal composition. The modified kaolin-based stickies removal composition is produced by modifying the kaolin clay, separating the modified kaolin clay from the non-reactive kaolin clay, and then adding a nonionic surfactant to the modified kaolin-based particles. Removal of stickies is improved by the use of this modified kaolin-based stickies removal composition during the recycling of the waste paper and paperboard.

The present invention relates to a copolymer comprising at least one hydrophilic monomer; at least one hydrophobic monomer and at least 10% by weight of methyl styrene, particularly suitable to be used as detackifying agent for reducing negative effects caused by natural pitch and/or adhesive contaminants in both pulping and papermaking operations.

The present invention relates to a copolymer comprising at least one hydrophilic monomer; at least one hydrophobic monomer and at least 10% by weight of methyl styrene, particularly suitable to be used as detackifying agent for reducing negative effects caused by natural pitch and/or adhesive contaminants in both pulping and papermaking operations.

The present invention provides a process for producing paper or board, comprising slushing a stock of dried fibres in a slushing system comprising a pulper, and/or feeding a stock of never-dried fibres in a fiber line of an integrated paper mill; deflaking and/or refining the stock in a deflaker and/or a refiner, optionally diluting the deflaked and/or refined stock, directing the deflaked and/or refined stock to a headbox, forming a web, and drying the web, wherein a polymeric paper making additive is added to one or more of the stocks of dried fibres and never-dried fibres before deflaking and/or refining of the stock. The present invention further provides paper and board with improved properties.

[Problem] To provide a contamination preventing agent composition capable of effectively preventing pitch contamination in a dry part. [Solution] The present invention relates to a contamination preventing agent composition for preventing pitch contamination in a dry part D of a papermaking process, the composition containing: a linear polysiloxane compound represented by formula (1); and a cyclic siloxane compound. [In formula (1), a substituent R.sup.1 represents, in the same molecule, a hydrogen atom, an alkyl group, a methylphenyl group, a polyether group, a higher fatty acid ester group, an amino-modified group, an epoxy-modified group, a carboxylic group, a phenol group, a mercapto group, a carbinol group, or a methacrylic group, and a repeating number n of a siloxane unit represents an integer of 20-1430.] ##STR00001##

The invention relates to a use of a water-soluble polymer product comprising amphoteric polyacrylamide, which has neutral or cationic net charge at pH 7, a weight-average molecular weight of 2 500 000-18 000 000 g/mol and a total ionicity of 4-28 mol-%. The polymer product is used for controlling deposit formation caused by hydrophobic substances in manufacture of paper or board, where a fibre web is formed from an aqueous suspension of fibres. The invention relates also to a method for controlling deposit formation caused by hydrophobic substances in manufacture of paper or board, where a fibre web is formed from an aqueous suspension of fibres, as well as to produced paper or board.

The invention relates to a use of a water-soluble polymer product comprising amphoteric polyacrylamide, which has neutral or cationic net charge at pH 7, a weight-average molecular weight of 2 500 000-18 000 000 g/mol and a total ionicity of 4-28 mol-%. The polymer product is used for controlling deposit formation caused by hydrophobic substances in manufacture of paper or board, where a fibre web is formed from an aqueous suspension of fibres. The invention relates also to a method for controlling deposit formation caused by hydrophobic substances in manufacture of paper or board, where a fibre web is formed from an aqueous suspension of fibres, as well as to produced paper or board.