Basf Aktiengesellschaft

Joachim Stedefeder

Hans-Uwe Schenck

Axel Sanner

Walter Denzinger

Sigberg Pfohl

Hermann Fischer

Juergen Hartmann

Wolfgang Schenk

Richard Thoma

Walter Kastenhuber

Ingo H Dorn

Heinz Leitner

Wolfgang Linke

Horst Kuhn

Bernd Kast

A process for the manufacture of paper having a high dry strength and a low wet strength, by treating the surface of the paper with an aqueous solution of an alkali metal and/or alkaline earth metal salt of a polymer of (a) from 91 to 100% by weight of acrylic acid and/or methacrylic acid and (b) from 0 to 9% by weight of acrylonitrile, methacrylonitrile, acrylamide, methacrylamide, vinyl acetate, maleic anhydride, diisobutylene, an ester of acrylic acid and/or an ester of methacrylic acid, which has a viscosity of from 5 to 100 mPas in 2% strength aqueous solution at 20.degree. C., and drying the impregnated paper. The polymer is generally employed in an amount of from 1 to 4% by weight, based on dry paper, and increases the dry strength of the paper without substantially increasing the wet strength.

Manufacture of paper having a high dry strength and a low wet strength

A process for sizing staple fiber yarns by applying an aqueous sizing liquor which contains an alkaline earth metal salt of a copolymer containing from 90 to 30% by weight of acrylic acid and/or methacrylic acid and from 10 to 70% by weight of acrylonitrile and/or methacrylonitrile, which copolymer has a viscosity of from 50 to 1,000 cp in 15% strength aqueous solution at 85.degree. C., and drying the treated yarns. The sized films obtained are moisture-insensitive and have good heat stability.

Water-soluble alkaline earth metal salts of polymers of acrylic acid,

Polymers in powder form are manufactured by polymerizing water-soluble ethylenically unsaturated monomers, which form hydrophilic polymers, in a powder bed of polymers of water-soluble ethylenically unsaturated compounds in the presence of polymerization initiators and water as an auxiliary liquid, the water being entirely or partially removed from the polymerization zone by evaporation during the polymerization.

Process for preparing polymers in powder form

Copolymers of crotonic acid are purified, to remove monomeric crotonic acid, by extracting the copolymers with water at from 50.degree. to 120.degree. C and stirring the system, the flow energy of the water and the energy of stirring being chosen so that the polymer particles just remain suspended.

Purification of copolymers containing crotonic acid

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Lampertheim, Germany

Joachim Stedefeder