FIELD: manufacture of pellets of foamed thermoplastic polymers, equipment for making such pellets.
SUBSTANCE: method is realized by using extrusion process and it comprises steps of increasing temperature of polymer till point higher than its melting temperature in extruder with one or several augers; adding at least one foaming agent to melt polymer; pelletizing polymer in apparatus for hot pelletizing of thermoplastic polymers. Such apparatus includes draw plate arranged in head of extruder and having cylindrical body with row of small plates on its surface. Said plates have row of openings for extrusion and large number of ducts for supplying melt polymer. Apparatus for pelletizing also includes cutting chamber with set of spraying nozzles for creating flow of drops of thermostatic-control liquid kept at temperature in range 10°C - polymer softening temperature and used for cooling and removing cut pellets due to spraying said liquid and splashing it by draw plate; cutting system with cutting plate rigidly secured to rotating shaft and carrying set of cutters mounted in such a way that cutting profile of cutter is arranged along radius relative to surface of draw plate turned to cutting system. Then produced pellets are annealed by heating them till temperature higher than glass transition temperature and cooled till 20°C. Apparatus for hot pelletizing of thermoplastic foamed polymers includes extruder with one or several augers; draw plate arranged in head of extruder; chamber having set of spraying nozzles and cutting system with cutting plate rigidly secured to rotating shaft and carrying set of cutters. Cutters are arranged in such a way that cutting profile of cutter is radial relative to surface of draw plate turned to said cutting system. Draw plate includes cylindrical body with row of small plates on its surface. Said small plates have row of openings for extrusion and row of ducts for supplying melt polymer arranged inside body. Tubular reactor for annealing pellets has length providing presence of pellets in it equal at least to 30 min. Produced pellets are not- oriented and not-stressed ones.
EFFECT: possibility for producing high-quality uniform cellular structure pellets with narrow distribution of their sizes.
18 cl, 4 dwg, 2 tbl, 6 ex
