An aramid-based paper comprising at least 90 wt. % of aramid material, the aramid material including at least one of aramid shortcut and aramid fibrid, the paper including at most 40 wt. % aramid pulp, calculated on the total amount of aramid material, wherein the paper includes 0.1-10 wt. % of polyamido-amine epichlorohydrin (PAE). It has been found that the incorporation of 0.1-10 wt. % of polyamido-amine epichlorohydrin (PAE) into an aramid-based paper including at least 90 wt. % of aramid material calculated on the weight of the paper not including the PAE, the aramid material including at least one of aramid shortcut and aramid fibrid, the paper including at most 40 wt. % aramid pulp, leads to a surprising improvement of the z-strength and the tear strength of the paper.

The present invention concerns a composition being an inverse emulsion comprising cross-linked anionic, organic polymeric microparticles, said microparticles having an unswollen z-average particle size diameter of less than 0.75 μm, wherein the organic polymeric microparticles are formed from a monomer mixture comprising (a) an ethylenically unsaturated carboxylic acid, or a salt thereof; (b) an ethylenically unsaturated non-ionic monomer; and (c) from 1 to 10 mole % of 2-acrylamido-2-methylpropanesulphonic acid, or a salt thereof. The invention also provides a process for preparing the composition, the use of the composition in a paper or paperboard making process and methods of making paper or paperboard employing said composition.

The present invention concerns a composition being an inverse emulsion comprising cross-linked anionic, organic polymeric microparticles, said microparticles having an unswollen z-average particle size diameter of less than 0.75 μm, wherein the organic polymeric microparticles are formed from a monomer mixture comprising (a) an ethylenically unsaturated carboxylic acid, or a salt thereof; (b) an ethylenically unsaturated non-ionic monomer; and (c) from 1 to 10 mole % of 2-acrylamido-2-methylpropanesulphonic acid, or a salt thereof. The invention also provides a process for preparing the composition, the use of the composition in a paper or paperboard making process and methods of making paper or paperboard employing said composition.

An aramid-based paper comprising at least 90 wt. % of aramid material, the aramid material including at least one of aramid shortcut and aramid fibrid, the paper including at most 40 wt. % aramid pulp, calculated on the total amount of aramid material, wherein the paper includes 0.1-10 wt. % of polyamido-amine epichlorohydrin (PAE). It has been found that the incorporation of 0.1-10 wt. % of polyamido-amine epichlorohydrin (PAE) into an aramid-based paper including at least 90 wt. % of aramid material calculated on the weight of the paper not including the PAE, the aramid material including at least one of aramid shortcut and aramid fibrid, the paper including at most 40 wt. % aramid pulp, leads to a surprising improvement of the z-strength and the tear strength of the paper.

Disclosed is an interpenetrating polymer network (IPN) that includes two polymers which are at least partially interlaced on a molecular scale, wherein the first polymer is obtainable by hydrolyzing a cross-linked poly(N-vinylformamide), and the second polymer is a copolymer of monomers A and B. The monomer A is preferably cationic, such as dimethylaminoethylacrylate methyl chloride, and the monomer B may be for example acrylamide. The IPN material may be used in paper making processes as drainage agent, retention agent, sizing agent or flocculant agent.

Disclosed is an interpenetrating polymer network (IPN) that includes two polymers which are at least partially interlaced on a molecular scale, wherein the first polymer is obtainable by hydrolyzing a cross-linked poly(N-vinylformamide), and the second polymer is a copolymer of monomers A and B. The monomer A is preferably cationic, such as dimethylaminoethylacrylate methyl chloride, and the monomer B may be for example acrylamide. The IPN material may be used in paper making processes as drainage agent, retention agent, sizing agent or flocculant agent.

The present invention concerns a composition being an inverse emulsion comprising cross-linked anionic, organic polymeric microparticles, said microparticles having an unswollen z-average particle size diameter of less than 0.75 m, wherein the organic polymeric microparticles are formed from a monomer mixture comprising (a) an ethylenically unsaturated carboxylic acid, or a salt thereof; (b) an ethylenically unsaturated non-ionic monomer; and (c) from 1 to 10 mole % of 2-acrylamido-2-methylpropanesulphonic acid, or a salt thereof.

The invention also provides a process for preparing the composition, the use of the composition in a paper or paperboard making process and methods of making paper or paperboard employing said composition.

The present invention concerns a composition being an inverse emulsion comprising cross-linked anionic, organic polymeric microparticles, said microparticles having an unswollen z-average particle size diameter of less than 0.75 m, wherein the organic polymeric microparticles are formed from a monomer mixture comprising (a) an ethylenically unsaturated carboxylic acid, or a salt thereof; (b) an ethylenically unsaturated non-ionic monomer; and (c) from 1 to 10 mole % of 2-acrylamido-2-methylpropanesulphonic acid, or a salt thereof.

The invention also provides a process for preparing the composition, the use of the composition in a paper or paperboard making process and methods of making paper or paperboard employing said composition.

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.