Abstract: The continuous preparation of melamine/formaldehyde precondensate solutions is carried out by a process in which melamine, formaldehyde and, if required, modifiers and/or additives are metered into a continuous mixer, and the homogeneous mixture is passed into a single-screw or twin-screw extruder, condensed at elevated temperatures, cooled and extruded.

Abstract: Solutions of low viscosity solvents and high viscosity, pasty products, for example water and sodium dithionite formulations, are prepared in a continuous manner in a matter of seconds in static and dynamic mixers connected in series while at the same time the ingress of air is avoided.

Abstract: A sheet-like packing material consisting ofA. from 2 to 90% by weight of melamine resin or phenol resin fibers and/or fibrids,B. from 5 to 90% by weight of finely divided inorganic fillers, preferably cement, andC. from 2 to 40% by weight of organic binders, preferably rubber, with or withoutD. from 0.1 to 50% by weight of thermoplastic fibrids, the percentages summing to 100,possesses low gas permeability, high compressive creep strength and advantageous compressibility, resilience and swelling behavior.

Abstract: A mixing head for multicomponent plastics, especially polyurethane, in whose mixing chamber (2) a hollow piston (7) can be moved to and fro to control the component streams. The hollow piston contains an expulsion piston (8), which is movable independently of the hollow piston, and which can be passed through an outlet tube (3) which adjoins the outlet orifice (4). The end face (12) of the hollow piston forms, together with the mixing chamber wall (11) nearest the sprue, a shearing gap in which the components are mixed. As a result of the design and arrangement of the pistons (7) and (8), good mixing is achievable even under critical conditions, and the mixing chamber is also easily cleaned.

Abstract: Process for the manufacture of .alpha.-naphthol by hydrolyzing .alpha.-naphthyl esters of aliphatic carboxylic acids in a distillation column by means of steam in counter-current at a particular temperature, and in a certain ratio, in the presence of organic sulfonic acids. The .alpha.-naphthol obtainable by the process of the invention is a valuable starting material for the manufacture of dyes, drugs and insecticides, e.g. .alpha.-naphthyl N-methylcarbamate.