Abstract: A method is disclosed for treating aqueous feed by dissolved gas flotation. The aqueous feed originates from industrial processing of fibrous material, where the aqueous feed includes an aqueous phase and solid particulate material suspended in the aqueous phase. The method includes bringing a flocculant in contact with the aqueous feed, flocculating suspended solid particulate material into flocs and contacting formed flocs with gas bubbles and inducing their flotation in a flotation basin. The flocculant includes a polymer composition having a charge density of at the most 1.7 meq/g dry and the polymer composition includes a cationic synthetic first polymer having a charge density at least 1.0 meq/g dry at pH 2.8, and at least one second polymer obtained by polymerization of (meth)acrylamide, the second polymer being polymerized in presence of the cationic first polymer, where the first polymer has a higher charge density than the second polymer.

Abstract: A method for dewatering of biological sludge is disclosed. The method includes addition of a flocculant to a biological sludge, which includes an aqueous phase and a suspended solid organic material, flocculating and dewatering the sludge. The flocculant includes a polymer composition, which includes a cationic crosslinked first polymer, which is selected from crosslinked polyamines, and a cationic second polymer, which is a polymer obtained by polymerization of (meth)acrylamide and cationic monomers, the second cationic polymer being polymerized in presence of the cationic first polymer.

Abstract: A polymeric structure, which is obtained by polymerisation of (meth) acrylamide and at least one charged monomer in a polymerisation medium comprising at least a first host polymer, which first host polymer comprises polyvinyl alcohol. The polymeric structure may be used in making of paper, board, tissue or the like as a strength agent, or in dewatering of sludge.

Abstract: The invention relates to a water-soluble polymer composition obtained by polymerizing in an aqueous polymerisation medium, which comprises degraded starch, at least following monomers: acrylamide and/or methacrylamide, and >2 mol-% of at least one unsaturated mono- or dicarboxylic acid(s) or salts thereof. The polymer composition has an anionic net charge at pH 7 and a dry solids content of >5 weight-%. The invention relates also to the use of the polymer composition for surface sizing of paper, board or the like as well as to a surface size composition comprising it.

Abstract: The invention relates to a water-soluble polymer composition obtained by polymerizing in an aqueous polymerisation medium, which comprises degraded starch, at least following monomers: acrylamide and/or methacrylamide, and >2 mol-% of at least one unsaturated mono- or dicarboxylic acid(s) or salts thereof. The polymer composition has an anionic net charge at pH 7 and a dry solids content of >5 weight-%. The invention relates also to the use of the polymer composition for surface sizing of paper, board or the like as well as to a surface size composition comprising it.

Abstract: A method is disclosed for treating aqueous feed by dissolved gas flotation. The aqueous feed originates from industrial processing of fibrous material, where the aqueous feed includes an aqueous phase and solid particulate material suspended in the aqueous phase. The method includes bringing a flocculant in contact with the aqueous feed, flocculating suspended solid particulate material into flocs and contacting formed flocs with gas bubbles and inducing their flotation in a flotation basin. The flocculant includes a polymer composition having a charge density of at the most 1.7 meq/g dry and the polymer composition includes a cationic synthetic first polymer having a charge density at least 1.0 meq/g dry at pH 2.8, and at least one second polymer obtained by polymerization of (meth)acrylamide, the second polymer being polymerized in presence of the cationic first polymer, where the first polymer has a higher charge density than the second polymer.

Abstract: A method is disclosed for dewatering of sludge from a pulp, paper or board making process, such as deinking sludge, including obtaining of an aqueous sludge including an aqueous phase and a fibre material suspended in the aqueous phase. The sludge is subjected to a pre-thickening step, where a first part of the aqueous phase is removed from the sludge and to a pressing step, where a second part of the aqueous phase is removed from the sludge, thereby obtaining a dry pressed sludge. Before or at the pre-thickening step a polymer composition having a charge density of at the most 1.7 meq/g, preferably at most 1.5 meq/g, more preferably at most 1.1 meq/g, is added to the sludge.

Abstract: A method for dewatering of biological sludge is disclosed. The method includes addition of a flocculant to a biological sludge, which includes an aqueous phase and a suspended solid organic material, flocculating and dewatering the sludge. The flocculant includes a polymer composition, which includes a cationic crosslinked first polymer, which is selected from crosslinked polyamines, and a cationic second polymer, which is a polymer obtained by polymerization of (meth)acrylamide and cationic monomers, the second cationic polymer being polymerized in presence of the cationic first polymer.

Abstract: 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.

Abstract: The present invention relates to an interpenetrating polymer network (IPN) material comprising microcrystalline cellulose (MCC), microfib-rillated cellulose (MFC) or a mixture thereof, and at least one polymer forming an IPN together with the MCC, MFC or mixture thereof. The present invention further relates to a process for producing the IPN material, and to use of the IPN material in paper industry.

Abstract: The present invention relates to an interpenetrating polymer network (IPN) material comprising a copolymer of vinylamine-vinylformamide, and a homo-polymer or a copolymer of at least one monomer selected from acrylamide or derivatives thereof, acrylic acid or derivatives thereof, or a mixture thereof forming the IPN material together with the copolymer of vinylamine-vinyl-formamide. The present invention further relates to a process for producing the IPN material, and to use of the IPN material in paper industry.

Abstract: A method is disclosed for dewatering of sludge from a pulp, paper or board making process, such as deinking sludge, including obtaining of an aqueous sludge including an aqueous phase and a fibre material suspended in the aqueous phase. The sludge is subjected to a pre-thickening step, where a first part of the aqueous phase is removed from the sludge and to a pressing step, where a second part of the aqueous phase is removed from the sludge, thereby obtaining a dry pressed sludge. Before or at the pre-thickening step a polymer composition having a charge density of at the most 1.7 meq/g, preferably at most 1.5 meq/g, more preferably at most 1.1 meq/g, is added to the sludge.

Abstract: 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.

Abstract: The present invention relates to an interpenetrating polymer network (IPN) material comprising a copolymer of vinylamine-vinylformamide, and a homo-polymer or a copolymer of at least one monomer selected from acrylamide or derivatives thereof, acrylic acid or derivatives thereof, or a mixture thereof forming the IPN material together with the copolymer of vinylamine-vinyl-formamide. The present invention further relates to a process for producing the IPN material, and to use of the IPN material in paper industry.

Abstract: New polyvinylamide and/or acryl acid-based copolymers. The new structured block copolymers are based on the block copolymerization of N-vinyl formamide (NVF) with other monomers by using a bifunctional initiator. Further, a method of preparing the structured block copolymer is provided, and especially a method wherein the NVF-based block is at least partially hydrolyzed to obtain PVAm. Also the use of the new structured block copolymers in sludge dewatering and in papermaking processes is disclosed.

Abstract: The present invention relates to an interpenetrating polymer network (IPN) material comprising microcrystalline cellulose (MCC), microfib-rillated cellulose (MFC) or a mixture thereof, and at least one polymer forming an IPN together with the MCC, MFC or mixture thereof. The present invention further relates to a process for producing the IPN material, and to use of the IPN material in paper industry.

Abstract: New polyvinylamide and/or acryl acid-based copolymers. The new structured block copolymers are based on the block copolymerization of N-vinyl formamide (NVF) with other monomers by using a bifunctional initiator. Further, a method of preparing the structured block copolymer is provided, and especially a method wherein the NVF-based block is at least partially hydrolyzed to obtain PVAm. Also the use of the new structured block copolymers in sludge dewatering and in papermaking processes is disclosed.

Abstract: The invention relates to a polymer product obtained by polymerization of i) at least one monomer selected from N-vinylformamide and vinyl acetate, and ii) maleic anhydride to give a copolymer comprising N-vinylformamide and/or vinyl acetate and maleic anhydride followed by hydrolyzing formamide groups originating from N-vinylformamide to amino groups and/or acetate groups originating from vinyl acetate to hydroxyl groups and acid anhydride to dicarboxylic acid groups to give a water-soluble copolymer comprising amine and/or hydroxyl and carboxyl groups, wherein the molar ratio of the N-vinylformamide and/or vinyl acetate monomer to the maleic anhydride monomer is from 70:30 to 30:70. The polymer product can be used as a dispersing agent or as a scale inhibiting agent.

Abstract: The invention provides an anionic dispersion polymerization process, wherein the polymerization is improved by an organic isothiocyanate, such as methyl isothiocyanate.

Abstract: The invention relates to a polymer product obtained by polymerization of i) at least one monomer selected from N-vinylformamide and vinyl acetate, and ii) maleic anhydride to give a copolymer comprising N-vinylformamide and/or vinyl acetate and maleic anhydride followed by hydrolyzing formamide groups originating from N-vinylformamide to amino groups and/or acetate groups originating from vinyl acetate to hydroxyl groups and acid anhydride to dicarboxylic acid groups to give a water-soluble copolymer comprising amine and/or hydroxyl and carboxyl groups, wherein the molar ratio of the N-vinylformamide and/or vinyl acetate monomer to the maleic anhydride monomer is from 70:30 to 30:70. The polymer product can be used as a dispersing agent or as a scale inhibiting agent.