Ceskoslovenska Akademie Ved

Rudolf Puffr

Jan Sebenda

The invention relates to a method for the preparation of polyamides with enhanced electric conductivity (specific resistance below 10.sup.9 .OMEGA..cm) by the anionic polymerization of lactams with 7 to 13 atoms in the ring using the usual basic polymerization initiators and accelerating activators. The polymerization is carried out in the presence of 2-20 wt. parts of plasticizers, e.g. N,N-dialkoxy or N,N-dialkylacrylamides or methacrylamides or their polymers, polyethyleneoxide, polyamides or lactams of higher concentration of amide groups than has the principal lactam, and 1-50 wt. parts of a very finely ground graphite and/or conductive black per 100 wt. parts of anhydrous principal lactam or mixture of lactams.The polymerization is performed in a mold to give directly the required article or in continuous reactors to various profiles or to form granulates. The semiconductive polyamide, which is the product of this invention, is suitable, for instance, for use as machine parts operating under conditions where the formation of electrostatic charges should be eliminated (e.g. in mines, chemical plants, etc.) or for articles where the conductivity is usefully employed (e.g. low temperature heating elements).

Method for the preparation of polymers of lactams having an enhanced

The invention relates to a method for the cationic polymerization of lactams either substituted or unsubstituted on the lactam ring, which contain 6-16 carbon atoms, in the presence of 0.05 - 10 mol. % based on the lactam of an anhydrous salt of Cu, Zn, B, Al, Ti, Si, V, Sb, Bi, Cr, Mo, W, Mn, Fe, Co, Ni and an inorganic or organic anion such as phosphate, pyrophosphate, phosphite, sulfate, halide, carboxylate and sulfonate in the presence of 0.05 - 5 mol. % of a protic organic or inorganic acid such as pyrophosphoric, phosphorous, hydrohalic carboxylic and sulfonic. These additives can be added to lactam below 180.degree. C and the polymerization is carried out at 150.degree. - 320.degree. C for 0.1 - 200 hr. The above-specified salts, also their mixtures, can be used. The polymerization can be carried out with mixtures containing two or more lactams. The process can be carried out in a solvent and in the presence of various anhydrous inorganic fillers, such as glass fibers, ground minerals, powdered metals, metal oxides, phosphates, sulfates or sulfides or graphite. The process can also be effectively conducted in the presence of organic dyes, plasticizers and emulsifiers. If the polymerization is performed with the salts of cations which are spontaneously reduced by the lactam during polymerization, finely dispersed metals are formed and remain suspended in the polymer.

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Rudolf Puffr