A polymer composition includes a first host polymer, which is a copolymer of (meth)acrylamide and at least one cationic first monomer, and a second polymer, which is a copolymer of (meth)acrylamide and at least one cationic second monomer. The second polymer is polymerised in presence of the first host polymer, and the first host polymer has a higher cationicity than the second polymer, the difference in cationicity of the first host polymer and the second polymer being at least 3 mol-%, at least 5 mol-%, more preferably at least 7 mol-%. The polymer composition has a standard viscosity of >2.0 mPas, measured at 0.1 weight-% solids content in an aqueous NaCl solution (1 M), at 25 C., using Brookfield VII T viscometer with UL adapter. The invention relates also to uses of said polymer composition.

A polymer composition includes a first host polymer, which is a copolymer of (meth)acrylamide and at least one cationic first monomer, and a second polymer, which is a copolymer of (meth)acrylamide and at least one cationic second monomer. The second polymer is polymerised in presence of the first host polymer, and the first host polymer has a higher cationicity than the second polymer, the difference in cationicity of the first host polymer and the second polymer being at least 3 mol-%, at least 5 mol-%, more preferably at least 7 mol-%. The polymer composition has a standard viscosity of >2.0 mPas, measured at 0.1 weight-% solids content in an aqueous NaCl solution (1 M), at 25 C., using Brookfield VII T viscometer with UL adapter. The invention relates also to uses of said polymer composition.

The present invention relates to a process for manufacturing a sheet of paper and/or board from a fibrous suspension, according to which, before the formation of said sheet, added to the fibrous suspension, at one or more injection points, are at least two retention aids respectively: (a) at least one water-soluble organic cationic polymer P1 having a cationicity greater than 2 meq.Math.g.sup.1, and (b) at least one water-soluble amphoteric polymer P2 of at least one anionic monomer and of at least one cationic monomer. The polymer P2 is added to the fibrous suspension after dissolving, in aqueous solution, the polymer P2 previously obtained by one of the following polymerization techniques: gel polymerization, suspension polymerization, inverse emulsion polymerization, dispersion polymerization. The polymer P2 has a factor F>2, said factor F being defined by the formula: F=UL.sup.2[(100A)/(100C)] with UL: Brookfield viscosity of the polymer P2 at 0.1% by weight in a 1M aqueous solution of NaCl, at 23 C., with a UL module and at 60 rev.Math.min.sup.1, A and C corresponding respectively to the molar percentages of the anionic and cationic monomers of the polymer P2.

The present invention relates to a process for manufacturing a sheet of paper and/or board from a fibrous suspension, according to which, before the formation of said sheet, added to the fibrous suspension, at one or more injection points, are at least two retention aids respectively: (a) at least one water-soluble organic cationic polymer P1 having a cationicity greater than 2 meq.Math.g.sup.1, and (b) at least one water-soluble amphoteric polymer P2 of at least one anionic monomer and of at least one cationic monomer. The polymer P2 is added to the fibrous suspension after dissolving, in aqueous solution, the polymer P2 previously obtained by one of the following polymerization techniques: gel polymerization, suspension polymerization, inverse emulsion polymerization, dispersion polymerization. The polymer P2 has a factor F>2, said factor F being defined by the formula: F=UL.sup.2[(100A)/(100C)] with UL: Brookfield viscosity of the polymer P2 at 0.1% by weight in a 1M aqueous solution of NaCl, at 23 C., with a UL module and at 60 rev.Math.min.sup.1, A and C corresponding respectively to the molar percentages of the anionic and cationic monomers of the polymer P2.

Methods of reducing paper dusting in a papermaking process, and a low dusting tissue having increased strength are provided. Application of a polymer comprising at least one amine-containing vinylic or allylic monomer to at least one surface of a paper web during the papermaking process reduces the dusting tendency of the paper, and increases both the wet and dry strength of the paper product.

Methods of reducing paper dusting in a papermaking process, and a low dusting tissue having increased strength are provided. Application of a polymer comprising at least one amine-containing vinylic or allylic monomer to at least one surface of a paper web during the papermaking process reduces the dusting tendency of the paper, and increases both the wet and dry strength of the paper product.

A method of producing paper and board by using at least one water-soluble amphoteric polymer is provided. The water-soluble amphoteric polymer is obtained by copolymerizing a monomer mixture containing a) at least one N-vinylcarboxamide, b) at least one monoethylenically unsaturated monomer having at least one free acid group or at least one acid group in salt form, c) optionally at least one monoethylenically unsaturated monomer other than components (a) and (b), and d) optionally at least one compound having two or more ethylenically unsaturated double bonds, and then partly or wholly hydrolyzing the COR.sup.1 groups of the polymer. The cationic monomer units and the anionic monomer units differ in their respective molar fractions, each based on the total number of moles of all monomer units, by not more than 10 mol % in absolute terms.

A method of producing paper and board by using at least one water-soluble amphoteric polymer is provided. The water-soluble amphoteric polymer is obtained by copolymerizing a monomer mixture containing a) at least one N-vinylcarboxamide, b) at least one monoethylenically unsaturated monomer having at least one free acid group or at least one acid group in salt form, c) optionally at least one monoethylenically unsaturated monomer other than components (a) and (b), and d) optionally at least one compound having two or more ethylenically unsaturated double bonds, and then partly or wholly hydrolyzing the COR.sup.1 groups of the polymer. The cationic monomer units and the anionic monomer units differ in their respective molar fractions, each based on the total number of moles of all monomer units, by not more than 10 mol % in absolute terms.

The present invention discloses a method for detackifying organic contaminants in the process of pulping and papermaking and a composition used for the same. Specifically, the invention discloses that the water circulation system of pulping and papermaking process can be provided with non-ionic cellulose ether and cationic coagulant in lower amount, through which, the deposition of organic contaminants can be inhibited under the synergistic action of pre-coagulation and detackification.

The present invention discloses a method for detackifying organic contaminants in the process of pulping and papermaking and a composition used for the same. Specifically, the invention discloses that the water circulation system of pulping and papermaking process can be provided with non-ionic cellulose ether and cationic coagulant in lower amount, through which, the deposition of organic contaminants can be inhibited under the synergistic action of pre-coagulation and detackification.