FIELD: metallurgy.
SUBSTANCE: here is disclosed pipe out of polymer micro-foamy material of impact strength over 100 %, coming to 400 % of impact strength per European standards for pipe of same dimension out of basic material in un-foamy state. Notably, impact strength of this pipe is measured at 0°C. By the procedure the pipe is fabricated out of polymer micro-foam, produced from foamy polymer composition. Not-foamed polymer composition including thermo-plastic polymer material, filler and, not necessarily, a modified additive, increasing impact strength, or viscosity modifier, is extruded through the extrusion head with utilisation of foaming gas under condition of 0.01-0.1 of weight share, preferably, 0.01-0.04 of weight share per 100 weight shares of thermoplastic polymer material. At that moment pressure in the extruder head drops below desorption pressure of foaming agent. Not-foamed composition is subjected to shear force to facilitate density of polymer composition below 80 % of density of not-foamed polymer composition. Foamed polymer composition would thus have cells of foam of average diametre below 50 mcm, while impact strength of pipe H50 out of polymer micro-foam at 0°C would exceed 100 % and would reach up to 400 % of impact strength by European standards for a pipe of the same dimensions out of not-foamed polymer composition. Additionally, here is disclosed head (1) for the extruder. Before its slit (2) the head has channel (3) converging from the slit at angle alpha corresponding from 10 to 180°, preferably from 10 to 90°. There is also described the extruder including the head for the extruder according to the invention.
EFFECT: upgraded impact strength of pipe.
25 cl, 1 dwg, 1 tbl, 3 ex
