Device and method for dispersing solids, liquids and gases in extruder

Abstract

The invention relates to a device and a method for dispersing solids, liquids and gases in an extruder having at least one shaft (1) on which at least one disc (4) with interruptions is mounted, which rotates together with the shaft, and a cover cylinder (2) which covers the shaft (1). A non-co-rotating disc (3) is arranged directly behind the disc in the flow direction of the product or in the direction opposite the flow direction of the product, said non-co-rotating disc likewise having an interruption, and wherein the co-rotating disc is combined with a rotating shaft and has a gap (14) in the direction of the cover cylinder, and the non-co-rotating disc is combined with the cover cylinder and has a gap (15) in the direction of the rotating mandrel.

Description

[0001] This application is a divisional application of the Chinese patent application with the same title, with application number 201680073342.3 and application date December 14, 2016. Technical Field

[0002] The invention relates to an apparatus comprising an extruder on which at least one co-rotating disk having an interruption is mounted on one or more shafts, and wherein a non-co-rotating disk likewise having an interruption is arranged directly after the co-rotating disk. The apparatus is suitable for dispersing solids, liquids and gases and has an improved dispersing effect. The invention further relates to a method for dispersing solids, liquids and / or gases in a plastic material. Background Art

[0003] Various types of extruders are known. Due to the simple construction, the most commonly used extruders are single-screw extruders (also synonymously single-shaft extruders), in which a single shaft rotates in a barrel. Another type is a multi-screw extruder (also synonymously multi-shaft extruder), in which a plurality of shafts rotate. Here, co-rotating and counter-rotating extruder shafts or combinations thereof are possible.

[0004] The dispersion of solids, liquids or gases in plastic materials by means of extruders is a frequently occurring task in polymer processing.

[0005] As known to those skilled in the art, insufficient dispersion has disadvantages. If solid dispersion is bad, then it may increase costs due to increased material consumption and reduced mechanical properties (e.g., due to formation of plaques). Poorly dispersed liquids are for example insufficiently distributed, or in the case of soluble liquids, still exist in free form after the dispersion step. Insufficiently distributed liquids cause uneven distribution of product properties, and therefore, for example, when a part of polymer has a high additive concentration and another part has a low concentration, may make the performance deteriorate. If a part of liquid still exists in free form at the head of the extruder, then it is possible that, for example, organic liquids, for example, escape from the bearing of a gear pump or spray at a high temperature at the nozzle. This may lead to pollution problems, damage to heated liquids, environmental problems caused by liquid evaporation, or even cause fires when igniting a segmented organic liquid in air.

[0006] Depending on the purpose of the process, poor gas dispersion may lead to inhomogeneous foam or to insufficient degassing, for example in the production of insulating materials.

[0007] Each dispersion process in the extruder is simultaneously associated with an energy input. Increased energy input generally leads to thermal or other product damage, which is undesirable. Therefore, an important technical goal is to improve the dispersion effect at the same energy input, or conversely, to reduce the energy input at the same dispersion effect. Summary of the invention

[0008] Therefore, the object of the prior art is to provide an apparatus comprising an extruder which has an improved dispersing effect and / or a reduced energy input.

[0009] This object is achieved by providing an apparatus according to the invention comprising an extruder, on the shaft(s) of which at least one disk having an interruption is mounted, which rotates co-rotating with the shaft, and a non-co-rotating disk likewise having an interruption is arranged directly behind the disk in the direction of product flow or in the direction opposite to the direction of product flow.

[0010] Surprisingly it has been found that the device according to the invention leads to improved dispersion at the same energy input. As long as improved dispersion is not required or not required to a certain extent, the energy input can be reduced.

[0011] The use of the device according to the invention therefore makes it possible to improve the product quality of the plastics material by improved homogenization and / or reduced energy input.

[0012] In the present invention, at least one disk is mounted on the shaft (or shafts) of the extruder, co-rotating with the shaft and having an interruption, and a non-co-rotating disk is arranged directly behind the disk in the product flow direction or in the direction opposite to the product flow direction, which also has an interruption. Here, the co-rotating disk is coupled to the rotating shaft and has a gap in the direction of the sleeve, and the non-co-rotating disk is coupled to the sleeve and has a gap in the direction of the rotating mandrel.

[0013] In order to increase the dispersion effect, it is preferred to arrange multiple combinations of such disks in succession; that is, the extruder has an alternating sequence of rotating and non-rotating disks. In addition, the present invention includes the following aspects: 1. A device comprising an extruder having at least one shaft (1) and a shroud (2), characterized in that: At least one disk (4) having an interruption is mounted on the shaft (1) and rotates together with the shaft (1). and a non-co-rotating disk (3) likewise having an interruption is arranged directly after the disk (4) in the product flow direction or in the direction opposite to the product flow direction; The co-rotating disc (4) is coupled to the rotating shaft (1) and has a gap (14) in the direction of the cover cylinder (2), and the non-co-rotating disc (3) is coupled to the cover cylinder (2) and has a gap (15) in the direction of the rotating core shaft (1). 2. The device according to embodiment 1 is characterized in that the extruder has an alternating sequence of rotating disks (4) and non-rotating disks (3). 3. The device according to embodiment 1 or 2 is characterized in that the gap s between the edge of the co-rotating disk (4) and the cover sleeve (2) is smaller than the thread depth g divided by 4; where g is the distance between the core diameter of the shaft (1) and the cover sleeve (2). 4. A device according to any of the preceding embodiments, characterized in that the ratio between the thickness of the rotating disk (4) and the diameter of the hood tube is 0.2 to 0.02, and the ratio between the thickness of the non-rotating disk (3) and the diameter of the hood tube is 0.2 to 0.02. 5. A device according to any of the preceding embodiments, characterized in that the ratio between the axial gap between the (one or more) rotating disks (4) and the (one or more) non-rotating disks (3) and the diameter of the hood is in the range of 0.01 to 0.15. 6. The device according to any one of the preceding embodiments is characterized in that the interruptions in the rotating disk and the non-rotating disk are respectively constructed as grooves, wherein the grooves can be arranged vertically (radially) relative to the rotation axis, or inclined relative to the rotation axis. 7. The device according to embodiment 6 is characterized in that the groove (7) in the non-rotating disk (3) is arranged in a spiral shape. 8. The device according to embodiment 6 or 7 is characterized in that the number of grooves (6) in the rotating disk (4) and the number of grooves (7) in the non-rotating disk (3) are 4 to 60 respectively. 9. The device according to any of the preceding embodiments, characterized in that the extruder is a multi-shaft extruder with intermeshing screw shafts. 10. The device according to embodiment 8 is characterized in that the grooves (6) of the (one or more) rotating disks (4) are arranged radially, and the grooves (7) of the non-co-rotating disks (3) are arranged partially radially and partially inclined. 11. Method for extruding a plastic material using the device according to any one of embodiments 1 to 10. 12. The method according to embodiment 11, characterized in that the extruder is used to disperse gaseous, liquid or powdered additives in the plastic material. 13. The method according to embodiment 11 or 12, characterized in that the plastic material is a thermoplastic or an elastomer. 14. The method according to embodiment 13, characterized in that the thermoplastic used is a homopolycarbonate or a copolycarbonate or a blend comprising at least one homopolycarbonate or copolycarbonate. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 A section through the extruder shaft ( 1 ) is shown by way of example.

[0015] Figure 2 Such grooves (6) are shown by way of example in a disc (4) which is coupled (left) and co-rotates with the shaft (1), and grooves (7) in a disc (3) which is coupled and non-co-rotates with the sleeve (2).

[0016] Figure 3 The case of a twin-shaft extruder is exemplified.

[0017] Figure 4 The case of a twelve-axis extruder is exemplified.

[0018] Figure 5 A preferred embodiment for a multi-shaft extruder is shown.

[0019] Figure 6 Taking the middle groove as an example, the groove (7) can be perpendicular to the rotation axis or at a certain angle thereto.

[0020] Figure 7 The arrangement of co-rotating disks (4) and non-co-rotating disks (3) in a twin-screw extruder is shown by way of example in cross section.

[0021] Figure 8 Shows Figure 2 Part of. DETAILED DESCRIPTION

[0022] Figure 1 By way of example, a section through an extruder shaft ( 1 ) is shown with a mantle ( 2 ) and a disk ( 3 ) coupled thereto, as well as a shaft ( 1 ) and a disk ( 4 ) coupled thereto and a rotating shaft ( 5 ).

[0023] In a preferred embodiment, the interruption of the co-rotating disk continues to the edge of the disk, ie the edge of the co-rotating disk is interrupted. Preferably, the interruption is configured as a groove, which may extend to the core diameter, but does not necessarily have to. Figure 2 By way of example, such a groove (6) is shown in a disk (4) which is coupled (left) and rotates together with the shaft (1), and a groove (7) in a disk (3) which is coupled and does not rotate together with the sleeve (2). The parts which rotate together with the shaft are respectively shaded diagonally; the stationary parts together with the sleeve (2) are shaded vertically. The grooves (6, 7) can be U-shaped or V-shaped.

[0024] The grooves (6, 7) are separated from one another by screw flights (8, 9).

[0025] In the present invention, the thread depth g is defined as the distance between the core diameter of the shaft and the sleeve (see Figure 8 , which shows Figure 2 of the part).

[0026] The gap s between the edge of the co-rotating disk and the cover sleeve must be less than g / 2. Preferably, s is less than g / 4, particularly preferably less than g / 8. The gap s is greater than g / 256, preferably greater than g / 128, particularly preferably greater than g / 64.

[0027] The ratio between the thickness of the rotating disk(s) and the diameter of the mantle sleeve is preferably from 0.2 to 0.02, particularly preferably from 0.15 to 0.03, very particularly preferably from 0.1 to 0.04.

[0028] The ratio between the thickness of the non-rotating disk(s) and the diameter of the mantle sleeve is preferably from 0.2 to 0.02, particularly preferably from 0.15 to 0.03, very particularly preferably from 0.1 to 0.04.

[0029] The ratio between the axial gap between the two disks and the diameter of the sleeve is preferably 0.01 to 0.15, particularly preferably 0.02 to 0.1, very particularly preferably 0.03 to 0.08.

[0030] In a preferred variant of the intermeshing multi-shaft extruder, the disks with interruptions are mounted on the shafts in co-rotating fashion where the screw shafts intermesh, and the non-co-rotating disks and the co-rotating disks in each case, without taking into account the gaps, cover at least 70%, preferably at least 80%, preferably at least 90% of the free cross section between the core diameter and the outer wall. By way of example, for Figure 3 The twin-shaft extruder and Figure 4 This is shown in the twelve-axis extruder in Figure 1. In these figures: - the spindle carrying the rotating disk (10) is shaded horizontally - the spindle not carrying the rotating disk (11) is shaded vertically - the co-rotating disk (12) is shaded from the lower left to the upper right - the non-co-rotating disk (13) is shaded from the lower right to the upper left.

[0031] Figure 7 The arrangement of co-rotating disks (4) and non-co-rotating disks (3) in a twin-screw extruder is shown in cross-section by way of example. Here, the shroud (2) and the non-rotating disks (3) associated therewith are vertically shaded, and the rotating screw (1) and the disks (4) associated therewith are each shaded differently diagonally.

[0032] When referring to "grooves" hereinafter, the term refers to both the grooves (6) on the co-rotating disk and the grooves (7) on the stationary disk.

[0033] In a preferred embodiment, the interruption of the rotating disk and the interruption of the non-rotating disk are respectively configured as grooves. In a cross section perpendicular to the axis of rotation, the grooves can be arranged radially or obliquely. The base of the groove is preferably equipped with a rounded shape to avoid notch stress and corners that are not washed by the product.

[0034] In a preferred embodiment for a multi-shaft extruder, the grooves (6) on the disk of the rotating axis are arranged radially (perpendicular to the axis of rotation), and the grooves (7) on the non-co-rotating disk are arranged partly radially and partly obliquely relative to the axis of rotation, so as to cover the gap area together, such as Figure 5 shown.

[0035] The edges of the grooves in the projection perpendicular to the direction of rotation are preferably parallel to or open relative to the gap (14) remaining between the rotating disk (4) and the sleeve (2) or between the stationary disk (3) and the mandrel (1). They are particularly preferably open towards the gap, such as for example Figure 2 As shown in .

[0036] If Figure 6 The groove (7) can be perpendicular to the axis of rotation or at an angle to it, as shown by the example of the middle groove. If the edges of the groove are not arranged perpendicular to the axis of rotation, they preferably follow a spiral. The preferred conveying direction can be set by the pitch of the spiral.

[0037] The number of grooves (6, 7) distributed over the circumference of the rotating disk (4) and the non-rotating disk (3) is preferably 4 to 60, particularly preferably 8 to 40, very particularly preferably 12 to 30.

[0038] The screw flights (8, 9) may have a rectangular cross section, or the corners may be rounded, or they may have a circular (circular, oval, etc.) cross section.

[0039] The invention further provides a method for extruding plastic material using the device according to the invention.

[0040] "Plastic material" is understood to mean a deformable material. Examples of plastic materials are polymer melts, in particular polymer melts of thermoplastics and elastomers, mixtures of polymer melts or dispersions of polymer melts with solids, liquids or gases.

[0041] The method of the invention is used to disperse gaseous, liquid or solid additives in plastic materials.

[0042] An important class of plastic materials are polymers.

[0043] Different properties are imparted to polymers by various types of solids. This can be, for example, mechanical strength, elastic modulus, electrical conductivity, toughness or color. Mechanical fillers can also help, in the case of polymers whose preparation is complex and / or energy-intensive, to partially replace the polymer by less complex solids.

[0044] The solids are usually present in agglomerated form and must be dispersed so that they can exert their effect.

[0045] The solid can be present in particulate form, for example calcium carbonate, talc or carbon black. This can also be fibers, for example glass fiber bundles (which should be separated from each other), bundles made of carbon fibers, or reinforcing fibers made of polymers such as aramid (Kevlar).

[0046] Plastic material can also be made of solid and liquid, for example paste or dough. Here, the mixing of liquid or the dispersion of solid are for example used to make paste or change its composition.

[0047] The dispersion of liquids in polymers can also be used for various purposes. The liquids can be, for example, additives that impart specific properties to the polymers, such as heat stabilizers, plasticizers, extender oils, UV stabilizers, oxygen scavengers, initiators for chemical reactions such as crosslinking or polymer degradation, catalysts, catalyst inhibitors, vulcanization accelerators, flame retardants, compatibilizers between different polymer phases or between polymers and solids, or processing aids, such as water for degassing the polymers.

[0048] The dispersion of gases in polymers can also be used for various purposes. In the production of polymer foams such as for insulation, this is an important step. In addition, the dispersed gases can also be used for polymer degassing.

[0049] The polymer can be a thermoplastic, for example polycarbonate, polyamide, polyester, in particular polybutylene terephthalate and polyethylene terephthalate, polyether, thermoplastic polyurethane, polyacetal, fluoropolymer, in particular polyvinylidene fluoride, polyether sulfone, polyolefin, in particular polyethylene and polypropylene, polyimide, polyacrylate, in particular polymethacrylate (methyl), polyphenylene oxide, polyphenylene sulfide, polyether ketone, polyaryletherketone, styrene polymer, in particular polystyrene, styrene copolymer, in particular styrene-acrylonitrile copolymer, acrylonitrile-butadiene-styrene block copolymer and polyvinyl chloride. Blends made of the listed thermoplastics can also be used, which are understood by those skilled in the art to refer to combinations of two or more of the thermoplastics. The method of the present invention is particularly preferably used in the manufacture and compounding of polycarbonates.

[0050] Other preferred materials are rubber. The rubber used is preferably at least one selected from the group consisting of styrene-butadiene rubber, natural rubber, butadiene rubber, isoprene rubber, ethylene-propylene-diene rubber, ethylene-propylene rubber, butadiene-acrylonitrile rubber, hydrogenated nitrile rubber, butyl rubber, halogenated butyl rubber, chloroprene rubber, ethylene-vinyl acetate rubber, polyurethane rubber, thermoplastic polyurethane, eucommia gum, acrylate rubber, fluororubber, silicone rubber, sulfur rubber, chlorosulfonyl-polyethylene rubber. Of course, a combination of two or more of the listed rubbers, or a combination of one or more rubbers and one or more plastics, can also be used.

[0051] These thermoplastics and elastomers can be used in pure form or in mixtures with fillers and reinforcing materials, such as, in particular, glass fibers, or in mixtures with one another or with other polymers or in mixtures with customary polymer additives.

[0052] In a preferred embodiment of the process according to the invention, additives are mixed into the plastic material, in particular into the polymer melt and the polymer melt mixture. The additives can be added to the extruder together with the polymer in the form of a solid, liquid or solution, or at least a part of the additives or all of the additives can be introduced into the extruder via a side stream.

[0053] Additives can impart various properties to polymers. They can be, for example, colorants, pigments, processing aids, fillers, antioxidants, reinforcing materials, UV absorbers and light stabilizers, metal deactivators, peroxide scavengers, alkaline stabilizers, nucleators, benzofurans and indolones that are effective as stabilizers or antioxidants, mold release agents, flame retardant additives, antistatic agents, colorants and melt stabilizers. For example, these are carbon black, glass fiber, clay, mica, graphite fiber, titanium dioxide, carbon fiber, carbon nanotubes, ionic liquids and natural fibers.

[0054] In another preferred embodiment of the process according to the invention, the plastic material introduced into the extruder contains monomers, oligomers and / or solvents, which are at least partially removed by the process according to the invention. In this embodiment, a gaseous entrainer is dispersed in the plastic material. The entrainer is preferably removed again in a subsequent step by applying a vacuum.

Claims

1. A device for extruding thermoplastics or elastomers, wherein the device comprises a multi-shaft extruder with intermeshing screw shafts and having at least one shaft (1) and a shroud (2), characterized in that: At least one disk (4) having an interruption is mounted on the shaft (1) and rotates together with the shaft (1). and a non-co-rotating disk (3) likewise having an interruption is arranged directly after the disk (4) in the product flow direction or in the direction opposite to the product flow direction; wherein the co-rotating disc (4) is coupled to the rotating shaft (1) and has a gap (14) in the direction of the cover cylinder (2), and the non-co-rotating disc (3) is coupled to the cover cylinder (2) and has a gap (15) in the direction of the rotating core shaft (1), and wherein the clearance s between the edge of the co-rotating disk (4) and the sleeve (2) is less than the thread depth g divided by 4; wherein g is the distance between the core diameter of the shaft (1) and the sleeve (2), and The interruptions in the rotating disk and the non-rotating disk are each designed as grooves, wherein the grooves can be arranged perpendicularly, ie radially, to the rotation axis or obliquely to the rotation axis.

2. The device according to claim 1, characterized in that: The extruder has an alternating sequence of rotating discs (4) and non-rotating discs (3).

3. The device according to claim 1 or 2, characterized in that: The ratio between the thickness of the rotating disk (4) and the diameter of the sleeve is a value of 0.2 to 0.02, and the ratio between the thickness of the non-rotating disk (3) and the diameter of the sleeve is a value of 0.2 to 0.

02.

4. The device according to claim 1 or 2, characterized in that: The ratio between the axial gap between the rotating disk (4) and the non-rotating disk (3) and the diameter of the sleeve is 0.01 to 0.

15.

5. The device according to claim 1, characterized in that: The grooves (7) in the non-rotating disk (3) are arranged in a spiral shape.

6. The device according to claim 1 or 5, characterized in that: The number of grooves (6) in the rotating disk (4) and the number of grooves (7) in the non-rotating disk (3) are 4 to 60 respectively.

7. The device according to claim 6, characterized in that: The grooves (6) of the rotating disk (4) are arranged radially, and the grooves (7) of the non-co-rotating disk (3) are arranged partly radially and partly obliquely.

8. Process for extruding thermoplastics or elastomers using the device according to any one of claims 1 to 7.

9. The method according to claim 8, characterized in that: The extruder is used to disperse gaseous, liquid or powdered additives in the thermoplastic or elastomer.

10. The method according to claim 9, characterized in that: The thermoplastics used are homopolycarbonates or copolycarbonates or blends comprising at least one homopolycarbonate or copolycarbonate.

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