Abstract: Slightly crosslinked, water-soluble polymaleic acid which is obtainable by polymerization of maleic anyhdride with from 0.1 to 10% by weight of a crosslinking agent in an aromatic hydrocarbon at from 60 to 200.degree. C. in the presence of from 1 to 20% by weight, based on maleic anhydride, of a peroxyester, and hydrolysis of the polymer to give slightly crosslinked polymaleic acid having a Fikentscher K value of from 8 to 20 (measured at 20.degree. C. in 5% strength aqueous solution at pH 7 as the Na salt), a process for the preparation of slightly cross-linked polymaleic acid, and its use as a water treatment agent for reducing boiler scale and hard water deposits in water-conveying systems.

Abstract: A process for the preparation of polymaleic acid by polymerizing maleic anhydride in an aromatic hydrocarbon at from 60.degree. to 200.degree. C., using from 1 to 20% by weight, based on maleic anhydride, of peroxyesters derived from saturated or ethylenically unsaturated carboxylic acids, as the polymerization initiators and hydrolyzing the polymer, the polymaleic acid thus obtained and the use of the polymaleic acid as an agent for reducing scale formation and hard water deposits in systems through which water flows.

Abstract: Detergents which contain from 0.01 to 20% by weight of oxyalkylated, carbonyl-containing polymers can be prepared by reacting.(A) a polymer which contains, as copolymerized units, one or more monoethylenically unsaturated C.sub.3 -C.sub.6 -carboxylic acids with(B) ethylene oxide, propylene oxide, n-butylene oxide, isobutylene oxide or a mixture of these, in an aqueous medium at up to 150.degree. C.

Abstract: A horizontal solid-bed polymerization reactor which is divided into a plurality of zones, for example a reaction zone, an after-reaction zone, a heating zone and a product discharge zone and possesses inlet and outlet openings for feeding substances into the zones and/or removing substances from the zones, the zones being separated from one another over a part of the reactor cross-section by means of weirs, wherein two drive shafts which are independent of one another and possess mixing elements are introduced into the solid-bed polymerization reactor in the middle.

Abstract: Copolymers which contain, as copolymerized monomer units, monoethylenically unsaturated mono- and dicarboxylic acids are prepared by a process in which(a) from 10 to 60% by weight of a monoethylenically unsaturated dicarboxylic acid of 4 to 6 carbon atoms, its salt and/or, if appropriate, its anhydride,(b) from 90 to 40% by weight of a monothylenically unsaturated monocarboxylic acid of 3 to 10 carbon atoms and/or its salt and(c) from 0 to 20% by weight of another, carboxyl-free monoethylenically unsaturated monomer which is copolymerizable with (a) and (b),the percentages being based on the sum of the monomers, are polymerized in the presence of from 0.5 to 5% by weight of a water-soluble free-radical-forming initiator in an aqueous medium at from 60.degree. to 150.degree. C.

Abstract: Pulverulent and/or granular additives for pulverulent detergents and cleaning agents, consisting of(a) from 80 to 20% by weight of one or more copolymers comprising from 40 to 90% by weight of (meth)acrylic acid and from 60 to 10% by weight of maleic acid and/or one or more copolymers comprising from 10 to 45% by weight of (meth)acrylic acid, from 10 to 45% by weight of maleic acid and from 10 to 60% by weight of one or more hydroxyalkyl (meth)acrylates where hydroxyalkyl is of 2 to 6 carbon atoms, if appropriate in the form of a partially or completely neutralized water-soluble salt,(b) from 20 to 80% by weight of nitrilotriacetic acid or its mono-, di- or trisodium or mono-, di- or tripotassium salt and(c) from 0 to 20% by weight of one or more additives conventionally used for detergent and cleaning agent formulations, the use of these pulverulent and/or granular mixtures as additives for pulverulent and/or granular detergents and cleaning agents, and processes for the preparation of the said additives.

Abstract: Water-soluble polymer powders are prepared by polymerizing water-soluble ethylenically unsaturated monomers in a powder bed in the presence of polymerization initiators and water while maintaining the powder state, removing the heat of polymerization by distilling off water and circulating the reaction mixture, by a process in which water-insoluble organic peroxides which are liquid at 20.degree. C. are used alone or as a mixture with up to 50% by weight, based on the initiator mixture, of water-soluble, organic azo initiators and/or water-insoluble solid peroxy-containing compounds, as polymerization initiators.

Abstract: Carboxyl-containing polymers which are water-soluble at least in the neutralized form are prepared by a method in which a monoethylenically unsaturated C.sub.3 -C.sub.5 -carboxylic acid is polymerized in the presence or absence of a carboxyl-free copolymerizable ethylenically unsaturated monomer in aqueous solution in the presence of polymerization initiator and of from 0.01 to 5% by weight, based on the monomers, of an inorganic acid of phosphorus in which the phosphorus has an oxidation state of from 1 to 4, its water-soluble salts, a water-soluble --PO(OH).sub.2 -containing compound and/or its water-soluble salts and, if required, a polymerization regulator. Virtually colorless or only slightly colored polymer solutions are obtained.

Abstract: Maleic anhydride copolymer powders are prepared by a process wherein a solution or dispersion of maleic anhydride in an alkyl vinyl ether and/or an alkene, containing from 3 to 25 moles of the alkyl vinyl ether and/or alkene per mole of maleic anhydride, is brought into contact with a powder bed under polymerization conditions, and is polymerized in the bed while the reaction mass is circulated and the powder state is maintained, and the heat generated during polymerization is removed by evaporating excess monomer which boils lower than maleic anhydride.