METHOD OF PLASTICS EXTRUSION Russian patent published in 2013 - IPC B29C47/40 

FIELD: process engineering.

SUBSTANCE: invention relates to extrusion of plastics, particularly, to production of polycarbonate. Extrusion is performed in two-screw or multiple-shaft extruder using screw elements with paired unilateral rotation and paired scraping screw shafts. Note here that screw profiles, both active and passive, feature the pattern "compaction section - transition section - channel section - transition section". Note that compaction section feature the pattern "ledge are - side area -ledge area" while channel section feature the pattern "clearance section - side section - clearance section". Transition section represents as sequence of screw profile areas starting with side area and ending also in side area. Note that screw element compaction section is described by side area location relative to screw profile rotational axis at angle δ_fb1 larger than half the opening angle between housing angles (δ_fb1 ≥arccos(0.5*a/ra)) or equal thereto. Ledge area is located relative to screw profile rotational axis at angle δ_kb1 smaller than or equal to angle difference of screw one-way Erdmenger profile on subtracting opening angle between housing angles (δ_kb1≤π-4*arccos(0.5*a/ra)). Another ledge area is located relative to screw profile rotational axis at angle δ_kb2 smaller than or equal to angle difference of screw one-way Erdmenger profile on subtracting opening angle between housing angles (δ_kb2≤π-4*arccos(0.5*a/ra)). Note that screw element compaction section is described by side area location relative to screw profile rotational axis at angle δ_fb1 larger than half the opening angle between housing angles (δ_fb1 ≥arccos(0.5*a/ra)) or equal thereto. Clearance area is located relative to screw profile rotational axis at angle δ_nb1 smaller than or equal to angle difference of screw one-way Erdmenger profile on subtracting opening angle between housing angles (δ_nb1≤π-4*arccos(0.5*a/ra)). Another clearance area is located relative to screw profile rotational axis at angle δ_nb2 smaller than or equal to angle difference of screw one-way Erdmenger profile on subtracting opening angle between housing angles (δ_nb2≤π-4*arccos(0.5*a/ra)).

EFFECT: higher extrusion pressure, reduced power consumption.

16 cl, 76 dwg, 17 tbl, 19 ex