Abstract: The present invention relates to powder coating compositions wherein the binder contains copolymers which are solid below 30.degree. C., prepared from olefinically unsaturated compounds and have a weight-average molecular weight (M.sub.w) of 1500 to 75,000, a content of free hydroxyl groups of 0.2 to 6.0% by weight and a content of intramolecular carboxylic acid anhydride groups (calculated as C.sub.4 H.sub.2 O.sub.3) of 1 to 30% by weight.

Abstract: This invention relates to a process for carrying out reactions which primarily occur during the transport of compounds in the liquid phase or at the liquid-gas interface. Starting components are reacted with one another and/or with gases of the inner space in a multi-phase flow tube having a liquid ring flow which may contain dissolved and/or dispersed constituents. Any necessary heat exchange takes place between the liquid and the wall of the tube or the gases.

Abstract: This invention relates to a continuous process for the production of polyisocyanate polyaddition products using a multi-phase reaction flow tube as reactor.

Abstract: This invention relates to an improved process for the production of high molecular weight polyurethanes which are free from isocyanate groups and are soluble in organic solvent in reduced reaction times. The reactants, polyol and isocyanate, for example, are mixed together with solvent and the temperature is permitted to rise under the effect of the heat of reaction. The reaction mixture is then cooled with solvent addition in such a way that the viscosity of the reaction mixture remains constant until the optimum temperature for the polyurethane formation reaction ("specific reaction temperature") is reached. The mixture is then gradually cooled until there is no residual isocyanate present and the polymer is recovered from the reaction mixture.