Extruder mixing

An extruder for producing a thermoplastic material having a first and second portion, namely:

• (a) an axially extending barrel;
• (b) first and second screw conveyers co-axially disposed within said barrel, said second conveyer co-axially disposed within said first screw conveyer with relative rotatable movement between said first and second screw conveyers so as to define a first passage for conveying thermoplastic material from an input to a melt zone and then an output and define second passage from said melt zone to said output wherein said first screw conveyer is mounted for rotational axial movement within said barrel and said second screw conveyer is fixed relative to said first screw conveyer;
• (c) a connecting passage for communication between said first and second passage whereby a first portion of said thermoplastic melt is conveyed through said first passage to said output and another portion of said thermoplastic melt is conveyed through said connecting passage to said second passage;
• (d) means for changing the characteristic of said first portion of thermoplastic melt comprising an inlet through said barrel for adding a pigment for producing thermoplastic material having a first coloured portion and a second coloured portion;
• (e) a plate disposed at said output for merging said first and second coloured portions together
• wherein said second screw conveyer includes an aperture through said second screw conveyor in the vicinity of said output and communicates with said plate.

An extruder for producing a thermoplastic material having a first and second portion comprising:

• (a) an axially extending barrel;
• (b) a first screw conveyer rotatably extending along said axis of said barrel, comprising a core and an external flight defining a first passage for conveying thermoplastic solid material from an input end to a thermoplastic melt zone and an output end;
• (c) said first screw conveyer having:
• (i) a bore adjacent said output end;
• (ii) axially extending passage through said core in said melt zone to said bore
• (d) a second screw conveyer fixedly axially disposed within said bore comprising a core and an external flight defining a second passage for communicating with said axially extending passage whereby a first portion of said thermoplastic melt is conveyed through said first passage to said output end and a second portion of said thermoplastic melt is conveyed from said axially extending passage through said second passage to said output end;
• (e) an aperture disposed through said barrel downstream of said axially extending passage for adding thermoplastic modifying resin to said first portion of said thermoplastic melt;
• (f) a plate for merging said first and second portions together.

An extruder for producing a thermoplastic material having a first and second portion comprising:

• (a) an axially extending barrel;
• (b) a first screw conveyor rotatably extending along said axis of said barrel, comprising a core and an external frlight defining a first passage for conveying thermoplastic solid material from an input end to a thermoplastic melt zone and an output end;
• (c) said first screw conveyor having:
• (i) a bore adjacent said output end;
• (ii) axially extending passage through said core in said melt zone to said bore;
• (d) a second screw conveyor fixedly axially disposed within said bore comprising a bore and an external flight defining a second passage for communicating with said axially extending passage whereby a first portion of said thermoplastic melt is conveyed through said first passage to said output end and a second portion of said thermoplastic melt is conveyed from said axially extending passage through said second passage to said output end;
• (e) aperture disposed through said barrel for adding thermoplastic modifying resin to said first portion of said thermoplastic melt;
• (f) a plate for merging said first and second portions together;
• wherein said plate includes a first plate opening for communication with said first passage and a second plate opening for communication with said second passage;
• and
• wherein said second screw conveyor includes an aperture there through for communication with said second plate opening.