JP2002506752A - Mixing method and mixing device - Google Patents

Abstract

(57) Abstract: (a) making a pre-blend of a polymeric material and an additive, the pre-blend may be heterogeneous and containing agglomerates; (C) feeding the intermediate blend into a second mixing device to form a final blend; and (d) feeding the intermediate blend into a second mixing device to form a final blend. Delivering the blend, wherein at least steps (b), (c) and (d) are performed as a continuous process, the method comprising mixing the flowable polymeric material with the particulate additive. .

Description

DETAILED DESCRIPTION OF THE INVENTION

TECHNICAL FIELD The present invention relates to the technology of mixing a flowable polymer material, such as an elastomer such as rubber, with a particulate additive, but is applicable to other polymer materials and indeed a wide range of other materials. .

BACKGROUND ART In the rubber industry in particular, it is necessary to mix an elastomeric material such as rubber with a filler or other additives such as carbon black. The elastomer is conventionally supplied in the form of a bale weighing about 20-25 kg. This results in a batch mixing operation in a standard manner. Various attempts have been made to introduce flexible automated processes with granular rubber, but have not been successful to date in terms of cost and material behavior issues.

[0003] Certain plastic compounding equipment can be used to mix certain particulate rubber compounds, but the results are far from optimal, as elastomers generally have different properties than most thermoplastics. It can never be used to process all rubber elastomers.

DISCLOSURE OF THE INVENTION The present invention provides a method and apparatus for mixing particulate additives with both particulate natural and synthetic rubbers and flowable polymeric materials suitable for thermoplastic and thermoset polymers. I do.

The present invention comprises (a) making a pre-blend of a polymeric material and an additive,
The preblend may be heterogeneous and contain agglomerates; (b) feeding the preblend into a first mixing device to consolidate and form an intermediate blend; Feeding the intermediate blend into a second mixing device to form a final blend; and (d) delivering the final blend, at least steps (b), (c).
And (d) are performed as a continuous process, wherein the method comprises mixing the flowable polymeric material with the particulate additive.

[0006] The first mixing device is a distributive mixin that reduces heterogeneity.
g arrangement). The second mixing device can consist of a dispersive mixing arrangement that breaks up agglomerates. However, the first mixing device may be constituted by a dispersion mixing device, and the second mixing device may be constituted by a distribution mixing device.

[0007] The polymer material itself can be formed in particulate or liquid form.

[0008] The preblend is made by adding the desired proportions of the particulate additive and the polymeric material to a hopper, from which the preblend is fed to a dispensing and mixing device,
It goes without saying that the pre-blend prepared in advance can be directly added to the hopper.

[0009] However, the preblend can be supplied from a hopper by a screw feeder and a compactor device. The screws have a constant pitch and consolidation is achieved by restricting the exit from the feeder and compactor device. The throttle may be comprised of a screw advance closure. However, the screws can also be configured to have a reduced pitch or flight depth towards the outlet to achieve or supplement the compaction of the preblend.

[0010] The particulate extender can be added to the thermoplastic polymer material in a melt screw feeder that feeds the pre-blend to the dispensing and mixing device. Fused screw feeders can concomitantly reduce volume by promoting melting of the thermoplastic polymer material and reducing pitch and / or thread height in the feed direction. The melt screw feeder device can be provided with an expansion zone in which the melt is depressurized and an inlet for the extender into the depressurized melt is provided.

[0011] The dispensing and mixing device has a cylindrical chamber in which a coaxial rotor is arranged, and the preblend can be introduced radially at the inlet end of the chamber.

[0012] The rotor of the dispensing and mixing device has a conveying and mixing screw, which has a large gap between the thread and the chamber wall, and which reverses and feeds the intermediate blend from the distributing and mixing device. Facilitates separation of screw rotation.

[0013] The preblend is heated or cooled by circulating a fluid in a dispensing and mixing device.

The dispersion mixing chamber is disposed at the outlet of the distribution mixing chamber coaxially with the distribution mixing chamber, and the inlet end of the dispersion mixing chamber can be smoothly connected to the outlet end of the distribution mixing chamber.

[0015] The dispersion mixing device has a blade device that rotates within the dispersion mixing chamber, the blade device having a small gap between the chamber walls so that the material undergoes elongational and shear flow. The dispersion mixing chamber has a conical shape that tapers in the direction of its exit. The cone angle of the blade device can be smaller than the cone angle of the dispersion mixing chamber, so that the gap between the blade and the wall decreases toward the outlet of the chamber.

The cone angle of the blade device can be constant or variable from end to end.

The blade arrangement has at least one blade (actually several blades) inclined with respect to the axis of the blade arrangement in order to be able to apply a conveying or pumping action to the intermediate blades processed in the dispersion mixing apparatus. Blade). However, the blade angle is such that the conveying or pumping action is not so strong as to have a significant effect on the residence time of the intermediate blend in the dispersion mixing device.

[0018] The material is heated by mechanical work applied to the material when feeding the material to the dispensing and mixing device and / or when processing the material in the distributing and mixing device, the heating being effected by the dispersion and mixing device. Complemented or controlled by additional heating or cooling by heating or cooling means (eg, passing a heat exchange fluid).

The heat exchange passages are advantageously provided in the rotor bodies in both chamber wall thicknesses and in both mixing zones.

The final blend is delivered to an extruder or roller die or calender means for producing sheet material. Or, in practice, the dispersion mixing device is delivered directly through an extrusion die.

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of a method and an apparatus for mixing a fluid polymer material and a particulate additive according to the present invention will be described below with reference to the accompanying drawings.

The drawings show: granular synthetic elastomers and natural rubbers and thermosetting plastics,
1 shows a method and apparatus for mixing flowable polymeric materials such as thermoplastics and thermoplastic elastomers with particulate additives such as carbon black and other materials including fibrous extenders.

The pre-blend of the polymeric material and the additives (the pre-blend, which may be heterogeneous or containing agglomerates), may be added to the hopper 11 either as an already mixed blend or separately in the desired ratio. Made by adding. The pre-blend is
It is fed into the dispensing and mixing device 12 where the heterogeneity is reduced and an intermediate blend is formed. The intermediate blend is fed into a dispersion mixing device 13,
Aggregates are broken within 3 to form the final blend. This final blend is then delivered, but the process is performed in a continuous manner.

The polymeric material itself may be in particulate form, reflecting recent attempts to introduce particulate rubber into the rubber industry instead of conventional veils based on standard procedures for batch processing. However, the device of the present invention can also handle liquid polymers.

FIGS. 1 and 2 show an apparatus for supplying a pre-blend from a hopper 11 to a distributing and mixing apparatus 12.

FIG. 3 shows a horizontal screw feeder and a material dispenser 12 from a hopper 11.
And a compactor device 18 for supplying the same. The screw 19 has a constant pitch P and a thread height D, and the consolidation is achieved by the outlet 21 from the compactor device 18.
(The consolidated preblend at this stage is referred to in the rubber industry term as a "rubber compound"). The throttle is provided by an adjustable screw advance closure 22. However, if desired, it can also be achieved by gradually reducing the pitch and / or thread height of the screw 19.

FIG. 5 shows the screw feeder and compactor device 18 in which the height D of the thread is reduced in the direction of the outlet over the first region E. In this region (preferably heating), the polymer (in this case, a thermoplastic) melts due to the consolidation of the polymer. At the end of the region E, the thread height D sharply increases to reduce the pressure, and at this end an inlet 23 is provided.
After the introduction, the material is repressurized and fed to the dispenser 12. By introducing the extender in this way, the wear problems associated with supplying the abrasive extender with the plastic granules or powder can be avoided or at least reduced.

The distribution mixer 12 has a cylindrical chamber 24 in which a coaxial rotor 25 is arranged. The preblend is introduced radially at the inlet end 24a of the chamber 24. The rotor 25 has a conveying / mixing screw 26. Screw 2
There is a large gap C between the No. 6 thread 26F and the chamber wall 24W to facilitate the pumping of the rotary screw 26 resulting from the backflow and the intermediate blend feed rate from the dispensing and mixing device 12. The preblend is significantly heated by mechanical work acting on the preblend in the dispensing and mixing chamber 24, but by cooling or providing additional heating by circulating the fluid at the appropriate temperature and flow rate in the channel 24b. Can be.

The dispersion mixing device 13 has a blade device 27 that rotates within the dispersion mixing chamber 28 with a narrow gap from the chamber wall 28a. The chamber 28 has a conical shape that is arranged coaxially with the chamber 24 at the outlet 24 c of the dispersion mixing chamber 24 and tapers in the direction of the outlet 29.

The blade device 27 is supported by the same rotor 25 as the transport / mixing screw 26.
The portion of the rotor 25 that supports the blade arrangement 27 is tapered similarly to the chamber 28, but has a smaller cone angle than the chamber 28 to increase material compaction toward the outlet 29 (blade). The cone angle of the device may be greater than or the same as the cone angle of chamber 28 in some situations). The blade arrangement 27 has a cone angle smaller than the cone angle of the chamber 28, and the gap between the blade and the wall decreases in the direction of the outlet 29. The cone angle of the blade device 27 is
Can be equal to or greater than the cone angle of As shown, the cone angle of the blade is constant from end to end, but is varied to provide a long length very close to the walls of the chamber 28 to more effectively disperse small agglomerates. Can also.

The blade device 27 has blades which are inclined with respect to the axis of the blade device in order to add a conveying or pumping action to the intermediate blend processed in the dispersion mixing device 13. However, the blade angle is so large that the transport or pumping action does not have a strong effect on the residence time of the intermediate blend in the dispersion mixing device 13.

The material is further heated by mechanical work applied to the material in the dispersion mixing device 13. The temperature of the material can be controlled to maintain the material at a temperature suitable for processing by additional heating or cooling using the fluid channels 25d, 28d.

FIG. 5 shows an apparatus for introducing a fiber extender into a formulation. An outlet 29 from the dispersion mixing device 13 leads into a screw feeder device 31 provided with an inlet port 32 for the fiber extender. The screw 33 supplies and consolidates the crude mixture of the polymer and the fibers, and supplies the crude mixture to a pin barrel mixing device 34 for dispersing and mixing the fibers. The exact details of the distributing mixer 12 and the dispersing mixer 13 are not important if only fibers are used for material expansion.

In all the illustrated embodiments, the rotor 25 is adapted to change the gap between the rotor blades of the dispersion mixing device 13 and the chamber walls to accommodate a wide variety of formulations.
The direction can be adjusted toward and away from the outlet 29. However, with a constant gap, a simple and inexpensive structure can be achieved.

FIG. 6 shows that the rotor 25 is (a) not adjustable (or not always adjustable) in the direction toward and away from the outlet 29 and (b) is cylindrical rather than tapered (conical) A mixer of the "budget" specification (excluding the end 25a) is shown.

FIGS. 3 and 6 show that the outlet 9 has an extruder 35 (vertical as shown,
4 may be horizontal, as shown in FIG. 4, while FIG. 4 shows an extrusion die 36 fixed directly to the outlet 29. Of course, the sheet material can also be manufactured by connecting roller dies or calendar means.

In the case of rubber production, a common raw material is a granular preblend of some or all of the components of the rubber compound, possibly using separately measured pelletized polymer and extender. The temperature at the various mixing stages, the back pressure set by various mechanical adjustments, the residence time or the extrusion when appropriately influenced by the speed of the rollers and screws or rotors, in order to obtain optimum extrusion speeds and rubber properties. Variables such as speed are set.

Some formulations, such as silica bulking formulations, have features that require more than one stage of mixing, such as by continuous passes through the same device or by connecting continuously connected devices. It can be done in a single pass through.

If the preblend is of a nearly uniform formulation, the dispensing and mixing equipment can be omitted altogether, and even at one or both ends of a single disperser some redistribution and improved uniformity Is achieved.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of a first embodiment.

FIG. 2 is a sectional view taken along the line II-II in FIG.

FIG. 3 is a longitudinal sectional view of a second embodiment.

FIG. 4 is a longitudinal sectional view of a third embodiment.

FIG. 5 is a longitudinal sectional view of a fourth embodiment.

FIG. 6 is a longitudinal sectional view of a fifth embodiment.

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Claims (60)

[Claims] 1. A method comprising: (a) making a pre-blend of a polymeric material and an additive, the pre-blend may be heterogeneous and containing agglomerates; (C) feeding the intermediate blend into a second mixing device to form a final blend; and (d) feeding the intermediate blend into a second mixing device to form a final blend. Delivering the final blend, at least steps (b) and (c).
And d) being carried out as a continuous process, wherein the flowable polymer material and the particulate additive are mixed. 2. The method of claim 1, wherein said first mixing device is a distributive mixing device that reduces heterogeneity. 3. The method of claim 1, wherein said second mixing device is a distributive mixing device that reduces heterogeneity. 4. The method according to claim 2, wherein the other mixing device is a dispersion mixing device for breaking up aggregates. 5. The method according to claim 2, wherein the polymer material is granular in itself. 6. The method according to claim 5, wherein the polymer material is mixed in a liquid state. 7. The preblend is made by adding desired proportions of particulate additives and polymeric material to a hopper, from which the preblend is fed to a dispensing and mixing device. 7. The method according to any one of 6. 8. The method of claim 7, wherein the preblend is supplied from a hopper by a screw feeder and a compactor device. 9. The screw having a constant pitch and a thread height,
9. The method according to claim 8, wherein consolidation is achieved by squeezing the outlet from the feeder and compactor device. 10. The thermoplastic polymer material in a melt screw feeder for supplying a pre-blend to the distributing / mixing device, wherein a particulate extender is added to the thermoplastic polymer material. the method of. 11. The molten screw feeder device according to claim 1, wherein the volume is concomitantly reduced by promoting the melting of the thermoplastic polymer material and reducing the pitch and / or thread height in the feed direction. Item 10. The method according to Item 10. 12. The method according to claim 10, wherein the molten screw feeder device has an expansion zone for depressurizing the melt and an inlet for an extender into the depressurized melt. . 13. The apparatus according to claim 2, wherein the dispensing and mixing device has a cylindrical chamber in which a coaxial rotor is arranged, and wherein the preblend is introduced radially at an inlet end of the chamber. Or the method of claim 1. 14. The method according to claim 13, wherein an adjustable throttle is provided at the inlet to the dispensing and mixing device. 15. The rotor according to claim 1, wherein said rotor has a conveying and mixing screw, said screw having a large gap between the thread and the chamber wall, and a counterflow of the intermediate blend from the distributing and mixing device and a screw from the feed rate. The method according to claim 13, wherein the separation of the rotation is facilitated. 16. The method according to claim 2, wherein the preblend is heated in a distributing mixer. 17. The dispersion mixing device has a blade device that rotates in a dispersion mixing chamber, the blade device having a small gap between the chamber wall so that the material undergoes elongational and shear flow. The method according to any one of claims 2 to 16, characterized in that: 18. The method according to claim 17, wherein the dispersion mixing chamber is disposed coaxially with the distribution mixing chamber at an outlet of the distribution mixing chamber. 19. The method according to claim 17, wherein the dispersion mixing chamber has a conical shape tapering in the direction of its outlet. 20. The method according to claim 19, wherein the cone angle of the blade device is smaller than the cone angle of the dispersion mixing chamber, and the gap between the blade and the wall decreases toward the outlet of the chamber. . 21. The method of claim 20, wherein the cone angle of the blade device is constant from end to end. 22. The method according to claim 20, wherein the cone angle of the blade device varies from end to end. 23. The blade arrangement having at least one blade inclined with respect to the axis of the blade arrangement so as to be able to convey or pump the intermediate blades processed in the dispersion mixing apparatus. 23. A method according to any one of claims 17 to 22, characterized in that: 24. The method according to claim 23, wherein the blade angle is such that the conveying or pumping action is not so strong as to significantly affect the residence time of the intermediate blend in the dispersion mixing device. The described method. 25. The material is heated by mechanical work applied to the material when feeding the material to the dispensing and mixing device and / or when processing the material in the dispensing and mixing device. A method according to any one of claims 2 to 24. 26. The method of claim 25, wherein the heating by mechanical work is supplemented or controlled by additional heating or cooling. 27. The method according to claim 26, wherein the additional heating or cooling is performed by heat exchange with a heating fluid circulating in a passage around the distribution mixing device. 28. The method according to claim 26, wherein additional heating or cooling is performed in the dispersion mixing device. 29. The method of claim 26, wherein the additional heating or cooling is controlled to maintain the material at a temperature optimal for processing. 30. The method according to claim 1, wherein the final blend is delivered to an extruder. 31. The method according to claim 1, wherein the final blend is delivered to a roller die or calendar means for producing a sheet material. 32. The method according to claim 1, wherein the final blend is delivered through a die directly from a dispersion mixing device. 33. A hopper for receiving the polymeric material and additives as a preblend; (b) a hopper delivery means to a first mixing device for forming an intermediate blend; and (c) a first mixing device. Mixing the flowable polymeric material with the particulate additive, characterized by having a second mixing device for forming a final blend, coupled to receive an intermediate blend from Equipment to do. 34. The apparatus according to claim 33, wherein said first mixing device is a distributive mixing device that reduces heterogeneity. 35. The apparatus of claim 33, wherein said second mixing device is a distributive mixing device that reduces heterogeneity. 36. Apparatus according to claim 34 or 35, wherein the other mixing apparatus is a dispersion mixing apparatus for reducing aggregates. 37. Apparatus according to claim 33, wherein said hopper delivery means comprises a screw feeder and compactor means. 38. Apparatus according to claim 37, comprising an adjustable throttle between said hopper delivery means. 39. The apparatus according to claim 38, wherein said adjustable throttle comprises a screw advance closure. 40. The screw having a constant pitch and thread height,
40. Compaction is achieved by means of an adjustable throttle.
An apparatus according to claim 1. 41. The screw according to claim 37, wherein the screw has a decreasing pitch or thread height towards the outlet end to achieve or supplement the compaction of the preblend. An apparatus according to claim 1. 42. Apparatus according to any one of claims 34 to 41, wherein the distribution compactor device has a cylindrical mixing chamber with a coaxial rotor. 43. Apparatus according to claim 42, wherein said hopper delivery means opens radially into the cylindrical mixing chamber at the inlet end of the cylindrical mixing chamber. 44. The rotor having a conveying and mixing screw, wherein the screw has a large gap between the threads and the chamber wall, and a screw from the backflow and feed rate of the intermediate blend from the distributive mixing zone. 44. Apparatus according to claim 42 or 43, which facilitates the breaking of the rotation. 45. Apparatus according to any one of claims 33 to 44, wherein said distributive mixing zone comprises heating means. 46. The apparatus according to claim 45, wherein said heating means has a passage for a heating fluid. 47. The dispersion mixing device has a blade device that rotates in a dispersion mixing chamber, the blade device having a small gap between the chamber wall so that the material undergoes elongational and shear flow. 47. A method according to claim 33, wherein
An apparatus according to any one of the preceding claims. 48. The apparatus according to claim 47, wherein the dispersion mixing chamber has a conical shape that tapers in the direction of its exit. 49. Apparatus according to claim 47 or 48, wherein the dispersion mixing chamber is arranged coaxially with the chamber at the outlet of the chamber. 50. The apparatus of claim 49, wherein the dispersion mixing chamber has an inlet end that is smoothly connected to an outlet of the distribution mixing chamber. 51. The blade device according to claim 48, wherein the cone angle of the blade device is smaller than the cone angle of the dispersion mixing chamber, and the gap between the blade and the wall decreases toward the outlet of the chamber. The apparatus according to claim 1. 52. The apparatus according to claim 51, wherein the cone angle of the blade device is constant from end to end. 53. The apparatus according to claim 51, wherein the cone angle of the blade device varies from end to end. 54. The blade arrangement having at least one blade inclined with respect to the axis of the blade arrangement so as to be able to convey or pump the intermediate blades processed in the dispersion mixing apparatus. 54. Apparatus according to any one of claims 47 to 53. 55. The method according to claim 54, wherein the blade angle is such that the conveying or pumping action is not so strong as to significantly affect the residence time of the intermediate blend in the dispersion mixing device. The described device. 56. The apparatus according to claim 47, wherein said dispersion mixing apparatus has a heating or cooling means. 57. The apparatus according to claim 53, wherein said heating or cooling means has a passage for a heat exchange fluid. 58. The apparatus according to claim 33, wherein an extruder is attached to an outlet of the dispersion mixing apparatus. 59. Apparatus according to any one of claims 33 to 58, comprising a roller die or calendar means mounted at the outlet of the dispersion mixing device. The apparatus according to any one of claims 33 to 53, wherein an extrusion die is provided at an outlet of the dispersion mixing apparatus.