Patent GB-839562-A (GB)
Title: Process and apparatus for recovery of plastic material from solution
Filed: 1956-10-04
Abstract: <PICT:0839562/III/1> <PICT:0839562/III/2> <PICT:0839562/III/3> <PICT:0839562/III/4> Plastic materials of molecular weight above 1,000, e.g. polymers or copolymers of 1-olefines or di-olefines, are recovered from viscous solutions in a solid disintegrated form in hydrocarbon solvents by passing the solution along a confined path under pressure sufficient to maintain the liquid phase, reducing the pressure to remove a substantial proportion of the solvent and solidify at least a portion of the plastic, and passing a cutter blade through the solidified material.  In a suitable apparatus, Figs. 1 and 2, the viscous effluent from a polymerization zone, after the removal of monomer, catalyst and up to 50% of solvent, e.g. a 10% solution of polyethylene in cyclohexane, is fed at 80 p.s.i.g. and 400 DEG  F. through a spray nozzle 53 to a flash chamber 24, fitted with a motor driven cutter with a plurality of bevelled, radial, cutting blades 48.  The flash chamber may be under vacuum, pressure, or atmospheric conditions and at least a portion of the polymer is solidified before reaching the cutter blades.  The chopper may be rotated at up to 5000 revs. per minute.  In a modification, Fig. 6, the discharge pressure reduction valve 60 is at a substantial distance, e.g. 24 inches, upstream and the discharge orifice 62 is closer, e.g. 1/16 to 1/2 inch, to the chopper blades.  An alternative chopper, Fig. 7, has an enlarged hub 70 holding pieces of wire 72. Material entering the flash chamber is effectively disintegrated without the formation of strings or ropes.ALSO:<PICT:0839562/IV (a)/1> <PICT:0839562/IV (a)/2> <PICT:0839562/IV (a)/3> <PICT:0839562/IV (a)/4> Plastic materials of molecular weight above 1000, e.g. polymers or copolymers of 1 - olefines, ethylene, propylene or 1-octene, and diolefines, are recovered in a solid disintegrated form from viscous solutions in hydrocarbons by passing the solution along a confined path under pressure sufficient to maintain the liquid phase, reducing the pressure to remove a substantial proportion of the solvent and solidify at least a portion of the plastic, and passing a cutter blade through the solidified material.  The viscous effluent, e.g. containing polyethylene in cyclohexane, from a polymerization zone, Figs. 1, 10, after removal of monomer 15, catalyst 19, and up to 50% of solvent 21, is fed at 80 p.s.i.g. and 400 DEG  F. through a spray nozzle 53 to a flash chamber 24, fitted with a motor-driven cutter with a plurality of bevelled, radial, blades 48 to form solid discrete polymer particles which may be extruded 25, cooled 28 and chopped 31.  The chopper may be rotated at up to 5000 revs. per minute.  In a modification, Fig. 6, the pressure reduction valve 60 is a substantial distance, e.g. 24 inches upstream and the discharge orifice 62, is closer, e.g. 1/16 to 1/2 inches to the chopper blades.  An alternative chopper Fig. 7, has an enlarged hub 70, holding pieces of wire 72.  Material entering the flash chamber is effectively disintegrated without the formation of strings or ropes.