Abstract: A process for preparing inherently light- and heat-stabilized polyamides comprises polymerizing in the presence of at least one triacetonediamine compound of the formula where R is hydrogen or hydrocarbyl having from 1 to 20 carbon atoms, preferably alkyl having from 1 to 18 carbon atoms, or benzyl.

Abstract: Polycaprolactam having a regulated amino end group content is produced in a continuous process in which caprolactam is polymerized at 240.degree.-290.degree. C. in the presence of water as initiator and in the presence of a dicarboxylic acid as chain regulator by polymerizing caprolactam in a single stage in the presence of from 0.3 to 5% by weight of water and from 0.1 to 0.6% by weight of terephthalic acid and/or isophthalic acid, each percentage being based on caprolactam, at a uniform pressure through the entire polymerization time of from 1.0 to 1.9 bar, measured in the vapor phase above the polymerization zone, while maintaining a water content of from 0.1 to 0.5% by weight, until the sum total of the amino and carboxyl end group contents is from 115 to 150 meq/kg, with the proviso that the amino end group content does not drop below 25 meq/kg, measured on extracted polycaprolactam.

Abstract: Nylons are prepared by a continuous process in which, in a precondensation zone, an aqueous solution of a salt of a dicarboxylic acid of 6 to 18 carbon atoms and a diamine of 6 to 18 carbon atoms is heated to 250.degree.-300.degree. C. under superatmospheric pressure, with simultaneous vaporization of water and formation of a prepolymer, the prepolymer and the vapor are separated, and the former is fed into a polycondensation zone and condensed under superatmospheric pressure of from 1 to 10 bar and at from 250.degree. to 300.degree. C., wherein the aqueous salt solution is condensed under superatomspheric pressure of from 1 to 10 bar in the first third of the tubular precondensation zone provided with baffles, until the degree of conversion is not less than 93%, and the prepolymer and the vapor phase are brought into intimate contact with one another in the remaining two thirds of the precondensation zone.

Abstract: A process for the continuous preparation of polycaprolactam, which comprises polymerizing .epsilon.-caprolactam in a vertical tubular reactor through which the .epsilon.-caprolactam flows downward, wherein the .epsilon.-caprolactam is partially polymerized, at a nylon-forming temperature, in a mechanically mixed zone, the reaction mixture is circulated through a heat exchange zone in the lower part of the mechanically mixed reaction zone, and is polymerized further, in additional heat exchange zones, until the desired degree of polymerization is reached, and poly-.epsilon.-caprolactam is then discharged as a melt, and an apparatus for carrying out the process.

Abstract: A process for the manufacture of nylons by heating an aqueous solution of a salt of an alkanedicarboxylic acid of 6 to 12 carbon atoms and a diamine of the formula NH.sub.2 RNH.sub.2, where R is alkylene of 6 to 12 carbon atoms or is a radical ##STR1## to a temperature at which a nylon is formed, under superatmospheric pressure and with removal of water. The solution used is an aqueous solution of from 75 to 90 percent strength by weight of a salt of a dicarboxylic acid and a diamine, which solution has been obtained by neutralizing a less concentrated salt solution, which contains an appropriate dissolved excess of the particular dicarboxylic acid, with the corresponding diamine. The nylons obtained are used for the manufacture of moldings.

Abstract: A process for the manufacture of a highly concentrated aqueous solution of a salt of a dicarboxylic acid and a diamine, as well as of a nylon precondensate, by reacting an alkanedicarboxylic acid of 6 to 12 carbon atoms and a diamine of the formula NH.sub.2 RNH.sub.2, where R is alkylene of 6 to 12 carbon atoms or is ##STR1## An aqueous solution, of lower concentration, of a salt of a dicarboxylic acid and a diamine, containing an appropriate dissolved excess of the particular dicarboxylic acid, is reacted with the particular diamine in the molten state, in an equivalent amount to the dissolved dicarboxylic acid, the reaction being carried out under superatmospheric pressure and the final reaction temperature being kept at from 140.degree. to 210.degree. C. The solution obtained is used for the manufacture of a nylon.

Abstract: An improved process for the continuous polymerization of .epsilon.-caprolactam in the presence of water as initiator in a vertical downward-flow tubular reactor, in which the .epsilon.-caprolactam is partially polymerized at elevated temperature in a first, mechanically agitated reaction zone and is further polymerized in further reaction zones to the desired degree of polymerization. Poly-.epsilon.-caprolactam is discharged in the form of a melt. The polymerization is carried out at a gauge pressure of from 0.2 to 0.9 bar, constant in all reaction zones. The temperature in the first reaction zone is maintained according to the relationship t.ltoreq.265+43 p .degree.C., where p is the numerical value of the gauge pressure in bars which relationship is subject to the condition that the temperature be within the range of 260.degree. to 295.degree. C.