Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01F—MIXING, e.g. DISSOLVING, EMULSIFYING OR DISPERSING
  • B01F27/00—Mixers with rotary stirring devices in fixed receptacles; Kneaders
  • B01F27/05—Stirrers
  • B01F27/07—Stirrers characterised by their mounting on the shaft
  • B01F27/074—Stirrers characterised by their mounting on the shaft having two or more mixing elements being concentrically mounted on the same shaft
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01F—MIXING, e.g. DISSOLVING, EMULSIFYING OR DISPERSING
  • B01F27/00—Mixers with rotary stirring devices in fixed receptacles; Kneaders
  • B01F27/21—Mixers with rotary stirring devices in fixed receptacles; Kneaders characterised by their rotating shafts
  • B01F27/2123—Shafts with both stirring means and feeding or discharging means
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01F—MIXING, e.g. DISSOLVING, EMULSIFYING OR DISPERSING
  • B01F27/00—Mixers with rotary stirring devices in fixed receptacles; Kneaders
  • B01F27/27—Mixers with stator-rotor systems, e.g. with intermeshing teeth or cylinders or having orifices
  • B01F27/272—Mixers with stator-rotor systems, e.g. with intermeshing teeth or cylinders or having orifices with means for moving the materials to be mixed axially between the surfaces of the rotor and the stator, e.g. the stator rotor system formed by conical or cylindrical surfaces
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01F—MIXING, e.g. DISSOLVING, EMULSIFYING OR DISPERSING
  • B01F25/00—Flow mixers; Mixers for falling materials, e.g. solid particles
  • B01F2025/91—Direction of flow or arrangement of feed and discharge openings
  • B01F2025/912—Radial flow

Definitions

• the present invention relates to a melt mixing device.
• the most common use is in the area of polymers where mixing of dissimilar materials and additives such as fillers, pigments, and plasticizers is a frequent procedure. Other applications may be in the ceramics and food processing industries.
• Specific mixing requirements are as varied as the materials to be mixed in terms of specific dispersion and distribution needs. While many effective mixing devices are known in the trade, none provide effective heat exchange capabilities so important in most processes of polymers.
• the combined application of mixing action and cooling synergistically enhances the efficiency of both. Good, efficient mixing was shown analytically by R.S. Spender and R.M. Wiley, and more recently by L. Erwin to be dependent on frequent interruption and reorientation of melt flow between points of high shear.
• Intrinsic to the present invention is a 180 degree reversal in flow direction at the end of each cylindrical blade, and the application of shear perpendicular to the main flow direction not available in any of the devices known in the art. Shear and mixing in general is accompanied by the generation of heat which leads to difficulties with heat sensitive materials and processes. This problem is readily controllable in subject invention apparatus while none of the prior art devices provide this feature. Summary of the Invention
• the present invention maximizes mixing capabilities by virtue of the fact that melt flow is reversed 180 degrees at the end of each cylindrical blade while simultaneously subjecting the melt of shearing forces transverse to the direction of the main stream. This in itself meets the condition for efficient mixing as defined by earlier cited theoreticians on the subject of mixing. Mixing capabilities of the present invention may be further enhanced by varying the clearance in the annular space between cylindrical blades, by interrupted flow channels or ridges, intermeshing pins, blades and similar obstructions variously employed in the art for the explicit purpose of mixing. A most effective mixer configuration is described in U.S. 4,447,156 which combined with the present invention results in a highly effective and efficient mixing and cooling apparatus.
• the most significant feature of the present invention is in the synergistic enhancement of mixing and thermal control which arises from the fact that virtually every particle within the melt is exposed to the temperature controlled surfaces of the stationary cylinders of subject mixer. This is particularly important with heat sensitive materials and processes.
• the mixing apparatus of this invention may be connected to the exit end of the plasticating extruder with the rotating element attached to the extruder tip and the stationary component to the barrel or die or both. Alternatively, the mixer may be operated as a separate unit having its own motor drive. Description of the Preferred Embodiment
• Fig. 1 illustrates an embodiment of subject invention apparatus 1 constructed in accordance to subject disclosure. It is connected to the end of an extruder 2 in which the screw performs the essential function of melting, plasticating and pumping the melt to the mixer.
• the revolving component of the mixer comprised of a multitude of concentrically positioned cylindrical, i.e., bell shaped, blades, is connected to the tip 5 of screw 3.
• This rotor revolves within a tapered cylinder 6 cored to allow circulating a cooling fluid -through it for precise temperature control of the mixing process 7.
• the stationary body of concentric cylinders 8 intermeshes with the cylindrical blades 4 of the rotor to form a nestled assembly of cylindrical blades with alternating stationary and revolving elements.
• the melt is thus forced to flow from the outer cylinder toward the center of the stationary body through the annular space formed by the intermeshing blades being, thereby, subjected to radial shear and axial flow shear simultaneously.
• Interrupted ridges 10, pins 11, blocks, grooves etc. provide enhanced mixing action as required.
• Points of high shear may also be incorporated by reducing the clearance in short segments of the annular space formed by the cylindrical blades.
• Cutting blades 13 revolving within radial channels with small clearance further enhance the mixing action.
• Melt conveying, i.e., pumping, flights may alternate with mixing elements to provide the desired balance of mixing and pumping.
• the stationary mixing element 8 is cored 12 to provide close temperature control at the points of high shear, i.e., at points of heat generation. What is claimed is:

Landscapes

• Chemical & Material Sciences (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Processing And Handling Of Plastics And Other Materials For Molding In General (AREA)
• Extrusion Moulding Of Plastics Or The Like (AREA)

Applications Claiming Priority (2)

Publications (1)

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Family Applications (1)

Country Status (2)

Families Citing this family (3)

Family Cites Families (8)

• 1987
  • 1987-04-16 WO PCT/US1987/000882 patent/WO1987006496A1/en unknown
  • 1987-04-16 EP EP87903132A patent/EP0267932A1/de not_active Withdrawn

Non-Patent Citations (1)

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