The present disclosure relates to a dry strength agent composition, use of an amine-containing cationic polymer for enhancing the dry strength of paper, and a method for enhancing the dry strength of paper. The dry strength agent composition includes at least two components. The first component is an amine-containing cationic polymer and the second component may be one or more anionic or amphoteric polymers.

A process for flocculating filler particles in water is provided. The process comprises adding a flocculant to a mixture comprising filler particles and water, wherein the flocculant has a reduced specific viscosity (RSV) of from about 5 dL/g to about 16 dL/g, a viscosity average molecular weight of from about 1,200,000 to about 7,500,000, and a cationic charge of from about 5 mol % to about 50 mol %. Flocs formed by flocculation of the filler particles and the flocculant have a median particle size of from about 10 m to about 150 m. The filler is not precipitated calcium carbonate alone. The flocs provided by the process are useful in increasing ash content of a paper product.

A process for flocculating filler particles in water is provided. The process comprises adding a flocculant to a mixture comprising filler particles and water, wherein the flocculant has a reduced specific viscosity (RSV) of from about 5 dL/g to about 16 dL/g, a viscosity average molecular weight of from about 1,200,000 to about 7,500,000, and a cationic charge of from about 5 mol % to about 50 mol %. Flocs formed by flocculation of the filler particles and the flocculant have a median particle size of from about 10 m to about 150 m. The filler is not precipitated calcium carbonate alone. The flocs provided by the process are useful in increasing ash content of a paper product.

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.

The invention relates to a method for producing paper, board or the like. The method comprises obtaining a fibre stock comprising lignocellulosic fibres and adding a retention agent system comprising a cationic synthetic polymer to the fibre stock and forming a fibrous web from the fibre stock and drying the web. Microfibrillated non-wood cellulose is added to the fibre stock as a component of the retention agent system and sequentially with the cationic synthetic polymer.

An absorbent towel paper web is disclosed. The absorbent towel paper web has from 20% to 90% of a soft wood pulp fiber mixture having from 18.5% to 88.5% of soft wood pulp fiber, wherein the soft wood pulp fiber is optionally refined; from 0.25% to 5.0% of cationic strengthening polymer, from 10% to 60% of a hard wood pulp fiber mixture; and not more than 10% moisture. The absorbent towel paper web has a Mean Square Dry Tensile Strength index ranging from 6 N.Math.m/g to 12 N.Math.m/g and a Wet Tensile Strength to Dry Tensile Strength Ratio value ranging from 0.295 to 0.35.

An absorbent towel paper web is disclosed. The absorbent towel paper web has from 20% to 90% of a soft wood pulp fiber mixture having from 18.5% to 88.5% of soft wood pulp fiber, wherein the soft wood pulp fiber is optionally refined; from 0.25% to 5.0% of cationic strengthening polymer, from 10% to 60% of a hard wood pulp fiber mixture; and not more than 10% moisture. The absorbent towel paper web has a Mean Square Dry Tensile Strength index ranging from 6 N.Math.m/g to 12 N.Math.m/g and a Wet Tensile Strength to Dry Tensile Strength Ratio value ranging from 0.295 to 0.35.

An absorbent towel paper product is disclosed. The absorbent towel paper product has two web plies. Each web has from 20% to 90% of a soft wood pulp fiber mixture having from 18.5% to 88.5% of optionally refined soft wood pulp fiber; from 0.25% to 5.0% of cationic strengthening polymer, from 10% to 55% of a hard wood pulp fiber mixture; and not more than 10% moisture. The two-ply paper product has a Mean Square Dry Tensile Index ranging from 10 N.Math.m/g to 18 N.Math.m/g and a Cross-directional Wet Tensile Strength to Cross-directional Dry Tensile Strength Ratio value ranging from 0.295 to 0.33.

An absorbent towel paper product is disclosed. The absorbent towel paper product has two web plies. Each web has from 20% to 90% of a soft wood pulp fiber mixture having from 18.5% to 88.5% of optionally refined soft wood pulp fiber; from 0.25% to 5.0% of cationic strengthening polymer, from 10% to 55% of a hard wood pulp fiber mixture; and not more than 10% moisture. The two-ply paper product has a Mean Square Dry Tensile Index ranging from 10 N.Math.m/g to 18 N.Math.m/g and a Cross-directional Wet Tensile Strength to Cross-directional Dry Tensile Strength Ratio value ranging from 0.295 to 0.33.