The present invention relates to a method for producing a cationic polyvinyl amine based copolymer. The present invention further relates to a cationic polyvinyl amine based copolymer and use of the copolymer in paper industry as a strength agent, a retention agent and a drainage agent.

A method of improving dry strength and/or drainage of a paper or paperboard by adding to a paper or paperboard furnish, a graft copolymer composition of a vinyl monomer and a functionalized vinylamine-containing base polymer graft copolymer.

A method of improving dry strength and/or drainage of a paper or paperboard by adding to a paper or paperboard furnish, a graft copolymer composition of a vinyl monomer and a functionalized vinylamine-containing base polymer graft copolymer.

The invention relates to powdery, water-soluble, cationic polymer composition comprising at least two different cationic polymers, namely a first cationic polymer and a second cationic polymer, which differ in chemical nature and molecular weight, as well to a method for producing such powdery, water-soluble, cationic polymer composition, and to its use for promoting flocculation in solid-liquid separation, for example as a retention aid in paper manufacture, and in sludge dewatering/wastewater purification.

The invention relates to powdery, water-soluble, cationic polymer composition comprising at least two different cationic polymers, namely a first cationic polymer and a second cationic polymer, which differ in chemical nature and molecular weight, as well to a method for producing such powdery, water-soluble, cationic polymer composition, and to its use for promoting flocculation in solid-liquid separation, for example as a retention aid in paper manufacture, and in sludge dewatering/wastewater purification.

The present invention relates to a process for the preparation of an aqueous polymer solution containing at least one cationic or amphoteric (co)polymer, comprising the following steps: Hofmann degradation reaction on a (co)polymer based on at least one non-ionic monomer chosen from the group including acrylamide, methacrylamide, N,N-dimethylacrylamide, and acrylonitrile; post-processing of the resulting aqueous polymer solution of viscosity V1; characterized in that the post processing comprises the following successive steps: obtaining of an aqueous polymer solution containing at least one cationic or amphoteric (co)polymer derived from the Hofmann degradation reaction; post-processing of this aqueous polymer solution; characterized in that the post processing comprises the following successive steps: (a) adjustment of the pH of the aqueous polymer solution to a value greater than or equal to 5.5; (b) decrease of the pH of the aqueous polymer solution to a value between 2 and 5. The invention also concerns the use of this polymer solution as a flocculant, retention and/or drainage agent, and dry strength resistance in a paper manufacturing process.

The present invention relates to a process for the preparation of an aqueous polymer solution containing at least one cationic or amphoteric (co)polymer, comprising the following steps: Hofmann degradation reaction on a (co)polymer based on at least one non-ionic monomer chosen from the group including acrylamide, methacrylamide, N,N-dimethylacrylamide, and acrylonitrile; post-processing of the resulting aqueous polymer solution of viscosity V1; characterized in that the post processing comprises the following successive steps: obtaining of an aqueous polymer solution containing at least one cationic or amphoteric (co)polymer derived from the Hofmann degradation reaction; post-processing of this aqueous polymer solution; characterized in that the post processing comprises the following successive steps: (a) adjustment of the pH of the aqueous polymer solution to a value greater than or equal to 5.5; (b) decrease of the pH of the aqueous polymer solution to a value between 2 and 5. The invention also concerns the use of this polymer solution as a flocculant, retention and/or drainage agent, and dry strength resistance in a paper manufacturing process.

Provided is a carboxymethylated microfibrillated cellulose fiber having a Canada standard freeness of less than 200 mL and an average fiber diameter of not less than 500 nm. Said fiber provides a composition having excellent water retention ability.

The present invention relates to a silica sol having a pH above about 10, molar ratio of SiO2:M2O, in which M is alkali metal, of from about 6:1 to about 16:1, concentration of soluble silica above about 3000 mg SiO2/l, and S-value of from about 18 to about 40%. The invention further relates to a process for producing a silica sol which comprises acidifying an aqueous alkali metal silicate solution to a pH of from 1 to 4 to form an acid sol, alkalizing the acid sol by addition of aqueous alkali metal silicate solution to obtain an intermediate sol and interrupt the addition of aqueous alkali metal silicate solution when the intermediate sol has reached a pH of from about 5 to about 8, stirring the intermediate sol for a time period of from about 10 to about 6000 seconds without addition of aqueous alkali metal silicate solution, alkalizing the intermediate sol by addition of aqueous alkali metal silicate solution to obtain a silica sol having a pH above about 10 and molar ratio of SiO2:M2O, in which M is alkali metal, of from about 6:1 to about 16:1, and optionally adding an aluminum compound to the acid sol, intermediate sol or silica sol. The invention further relates to a silica sol obtainable by the process of the invention. The invention further relates to the use of the silica sol as a flocculating agent, in water purification and in producing paper and board. The invention further relates to a process for producing paper and board which comprises: (i) providing an aqueous suspension comprising cellulosic fibers; (ii) adding to the suspension one or more drainage and retention aids comprising the silica sol; and (iii) dewatering the obtained suspension to provide a sheet or web of paper or board.

The present invention relates to a silica sol having a pH above about 10, molar ratio of SiO2:M2O, in which M is alkali metal, of from about 6:1 to about 16:1, concentration of soluble silica above about 3000 mg SiO2/l, and S-value of from about 18 to about 40%. The invention further relates to a process for producing a silica sol which comprises acidifying an aqueous alkali metal silicate solution to a pH of from 1 to 4 to form an acid sol, alkalizing the acid sol by addition of aqueous alkali metal silicate solution to obtain an intermediate sol and interrupt the addition of aqueous alkali metal silicate solution when the intermediate sol has reached a pH of from about 5 to about 8, stirring the intermediate sol for a time period of from about 10 to about 6000 seconds without addition of aqueous alkali metal silicate solution, alkalizing the intermediate sol by addition of aqueous alkali metal silicate solution to obtain a silica sol having a pH above about 10 and molar ratio of SiO2:M2O, in which M is alkali metal, of from about 6:1 to about 16:1, and optionally adding an aluminum compound to the acid sol, intermediate sol or silica sol. The invention further relates to a silica sol obtainable by the process of the invention. The invention further relates to the use of the silica sol as a flocculating agent, in water purification and in producing paper and board. The invention further relates to a process for producing paper and board which comprises: (i) providing an aqueous suspension comprising cellulosic fibers; (ii) adding to the suspension one or more drainage and retention aids comprising the silica sol; and (iii) dewatering the obtained suspension to provide a sheet or web of paper or board.