Abstract: A process for removing caprolactam and its oligomers from cooling water containing these compounds, wherein gases are introduced into the cooling water and the foam which forms is separated off.

Abstract: A melt of synthetic material is forced through orifices of a die plate, and the resulting strands of melt are led into a trough, where they travel in counter-current to a stream of cooling water. At the end of the trough, the strands are discharged, for further processing. The bottom of the trough merges into a vertical pipe and the melt strands are led into this pipe and out again, in a variable loop, in order to obtain the desired length of cooling path.

Abstract: An improved process for the preparation of fiber-forming polycaprolactam by polymerizing .epsilon.-caprolactam, and an aqueous extract containing .epsilon.-caprolactam and caprolactam oligomers, which extract has been obtained by extracting polycaprolactam with water, wherein the aqueous extract contains from 0.1 to 5.0% by weight of oligomers of caprolactam, based on the monomeric caprolactam in the aqueous extract.

Abstract: An improved process for the continuous preparation of polycaprolactam, in which .epsilon.-caprolactam is partially polymerized, with the addition of a water-containing agent and acetic acid or propionic acid as a chain regulator, at a nylon-forming temperature, in a mechanically mixed zone in a vertical tubular reactor through which the reaction mixture flows downwards, and is then polymerized further, in additional heat exchange zones, until the desired degree of polymerization is reached, and polycaprolactam is then discharged as a melt, wherein a gaseous mixture of caprolactam, water and acetic acid or propionic acid is removed at the top of the tubular reactor and is fed to the middle of a column, water is removed at the top of the column, the bottom of the column is maintained at from 125.degree. to 145.degree. C., and the mixture obtained at the bottom of the column, and comprising caprolactam, acetic acid or propionic acid and a small amount of water, is recycled to the top of the tubular reactor.

Abstract: Concentrates of from 20 to 50% by weight of titanium dioxide in polycaprolactam are produced by a process in which a 5-15% strength by weight aqueous suspension of titanium dioxide is metered into a solution of caprolactam in water at from 100.degree. to 150.degree. C. at the same rate at which water is distilled off, and after the water has been distilled off the resulting mixture is polymerized at from 240.degree. to 280.degree. C.

Abstract: Salts of alkanedicarboxylic acids of 4 to 12 carbon atoms and diamines of the formula H.sub.2 N--R--NH.sub.2, where R is alkylene of 2 to 12 carbon atoms or is a radical of the formula ##STR1## which contain hydrazine hydrate, the manufacture of the salts in solution, and their use for the manufacture of nylons.

Abstract: A process for the continuous manufacture of linear, high molecular weight, polybutylene terephthalates, in which dimethyl terephthalate is trans-esterified with 1,4-butanediol, if desired in the presence of up to 40 mole% of other starting materials which form linear polyesters, in the molar ratio of from 1:1.2 to 1:1.5, in a plurality of successive stages at temperatures rising from 160.degree. to 230.degree. C, the mixture thus obtained is passed, at from 230.degree. to 270.degree. C and from 2 mm Hg to 20 mm Hg, upward through a bundle of stationary heated tubes, and immediately thereafter through a hold tank, with the proviso that the volume of the hold tank is at least 1/4 and at most 2.5 times the volume of the tube bundle and the mean residence time in the tube bundle and hold tank together is from 10 to 60 minutes, and the precondensate thus obtained is polycondensed at from 240.degree. to 260.degree. C and from 0.1 to 2 mm Hg. with continuous formation of thin films.