Fremgangsmåde til kontinuerlig indvendig coatning af et stift ekstruderet hulprofilemne af termoplastisk plast

For continuously coating the inside of an extruded thermoplastic polymer tube, a rigid thermoplastic having a glass transition temperature above 50 DEG C is continuously extruded to form a polymer tube extrudate and after cooling below the glass transition temperature, led with elastic curvature along a downwardly curved arcuate path, where the inner wall of the hollow extrudate comes into contact with a reserve of a low viscosity coating agent which can wet the thermoplastic, the reserve remaining stationary there. After it has passed through this path section, the hollow chamber extrudate is guided upwards until the entrained excess of liquid coating agent has run back into the reserve. Subsequently the film of coating agent remaining on the polymer surface is cured to form a hard coating.