Method for preparing rubber

Abstract

The invention relates to a method for producing rubber from a rubber-containing dispersion (1), said method comprising: (a) feeding the rubber-containing dispersion (1) and a precipitation solution (3) into a precipitation tank (5), producing an aqueous suspension (9) containing rubber particles; (b) optionally sintering the rubber particles contained in the aqueous suspension (9) containing rubber particles to form larger particles; (c) mechanically dewatering the aqueous suspension (9) containing rubber particles to obtain rubber particles (33) containing residual moisture and a liquid phase (35) containing finely divided rubber particles, and returning the liquid phase (35) containing finely divided rubber particles to the precipitation tank (5).

Description

manual

[0001] The present invention relates to a method for processing rubber from a rubber-containing dispersion, wherein the rubber-containing dispersion and a precipitation solution are supplied to a precipitation vessel to produce an aqueous suspension containing rubber particles, the rubber particles present in the aqueous suspension containing rubber particles are optionally sintered to provide larger particles, and the aqueous suspension containing rubber particles is mechanically dewatered to obtain rubber particles containing residual moisture and a liquid phase containing finely divided rubber.

[0002] The granulated rubbers which can be treated with the process according to the invention are generally used as impact modifiers in the production of thermoplastic polymers or other plastics, in particular in the production of styrene copolymers, such as acrylonitrile-butadiene-styrene copolymers (ABS) or acrylonitrile-styrene-acrylate copolymers (ASA). These thermoplastic products can then be used very flexibly for molding compounds and molded parts.

[0003] The granular rubber, in particular the butyl acrylate grafted rubber or the butadiene grafted rubber, is usually produced by emulsion polymerization in an aqueous system followed by precipitation from a precipitation solution. The resulting granules are then usually dehydrated, for example by filtering, sieving, decanting, pressing out the water or centrifuging, optionally washed with water during or subsequently to the dehydration, and then optionally further water is removed by thermal drying.

[0004] Processes for producing granular rubber as a production component for ASA or ABS molding compounds are described, for example, in EP-A 0 734 825, WO-A 2020 / 043690, WO-A 2015 / 000873 or WO-A 2015 / 004112. To maximize the space-time yield, dispersions are usually produced with a solids content of 30% by weight or more.

[0005] A disadvantage of all known processes is that the water separated off during the dewatering process still contains rubber particles which are usually sent to disposal together with the separated water.

[0006] Furthermore, finely divided rubber that is not retained during the dewatering process due to the mesh size of the screen or the pore size of the filter enters the wastewater and must be removed from the wastewater during wastewater treatment and then sent for disposal. Precipitated salts present in the separated water are also completely disposed of via the wastewater. Likewise, precipitation of dispersions with a high solids content can easily lead to clogging of precipitation and / or sintering process components.

[0007] It is therefore an object of the present invention to provide a process for processing rubber from a rubber-containing dispersion which provides better yields and which minimizes the amount of product and precipitated salts removed from the process with the water while minimizing the risk of clogging of precipitation and / or sintering process parts.

[0008] This object is achieved by a method for processing rubber from a dispersion containing rubber, the method comprising: (a) providing a dispersion containing rubber and a precipitation solution to a precipitation vessel to obtain an aqueous suspension containing rubber particles, (b) optionally sintering the rubber particles present in the aqueous suspension containing rubber particles to obtain larger particles, (c) mechanically dewatering the aqueous suspension containing rubber particles to obtain rubber particles containing residual water and a liquid phase containing finely divided rubber, Therein, the liquid phase containing the finely divided rubber is recycled to the precipitation vessel. It has also been found that reducing the solids content of a dispersion having a solids content of more than 30% to less than 25% by weight significantly reduces the tendency to blockage during precipitation and / or sintering.

[0009] Since the liquid phase containing the finely chopped rubber is recycled to the precipitation vessel, the finely chopped rubber recycled together with the liquid phase is usually repeatedly subjected to thermal stress at least twice, because the precipitation in the precipitation vessel and / or the sintering in the sintering vessel are usually carried out at high temperatures.

[0010] Surprisingly, we have found that repeated thermal stressing of the polymer particles in the liquid phase containing the finely divided rubber recycled to the precipitation vessel does not adversely affect the mechanical properties of the product containing the rubber treated by the process of the invention, and that such recycling therefore increases the yield of rubber while maintaining the quality of the product, while minimizing the amount of rubber removed from the process with the wastewater. The amount of wastewater and therefore the amount of precipitation salts required is also minimized, while precipitation and / or sintering can be carried out simultaneously with a reduced solids content, thereby reducing the risk of blockages in this process step.

[0011] The rubber treated according to the method of the invention may be a grafted rubber. Preferably, it is a rubber comprising a graft shell of one or more other (usually non-elastic) polymers. For this purpose, the monomers butadiene, isoprene, chloroprene, styrene, alkylstyrene, acrylic acid or methacrylic acid may be used. 10 The single-stage or multi-stage elastomeric base stage is obtained by polymerizing one or more of alkyl esters and a small amount of other monomers (including cross-linkable monomers), and the hard graft layer is polymerized by one or more of styrene, alkyl styrene, acrylonitrile, and methyl methacrylate monomers. C1 to C2 based on monomers butadiene, isoprene, chloroprene, styrene, alkyl styrene, acrylic acid or methacrylic acid can also be used. 10 The starting stage is produced by using seeds obtained from alkyl esters and small amounts of other monomers (also crosslinkable monomers).

[0012] Preferred are rubbers based on butadiene / styrene / acrylonitrile, n-butyl acrylate / styrene / acrylonitrile, butadiene / n-butyl acrylate / styrene / acrylonitrile, n-butyl acrylate / styrene / methyl methacrylate, butadiene / styrene / acrylonitrile / methyl methacrylate and butadiene / n-butyl acrylate / methyl methacrylate / styrene / acrylonitrile. Up to 10% by weight of polar monomers or crosslinking monomers carrying functional groups can be incorporated into the seed and / or core and / or shell by polymerization.

[0013] Examples of rubbers treated according to the process of the invention include polymers of conjugated dienes (e.g. butadiene with an external graft shell, especially based on vinyl aromatic compounds, such as SAN copolymers). The rubber may also be a C1- to C2-based acrylic acid. 10 - Graft rubbers of crosslinked polymers of alkyl esters, such as n-butyl acrylate or ethylhexyl acrylate, grafted with polymers based on vinyl aromatic compounds, such as SAN copolymers.

[0014] The method is also applicable to grafted rubbers that generally comprise copolymers of conjugated dienes and C1 to C12 alkyl acrylates (e.g., butadiene-n-butyl acrylate copolymers) and one or more grafted layers consisting of SAN copolymers, polystyrene or PMMA. Butadiene grafted rubbers and butyl acrylate grafted rubbers are particularly preferred.

[0015] Rubbers are usually produced in aqueous systems, for example by emulsion polymerization, as described, for example, in WO-A 2020 / 043690.

[0016] Emulsion polymerization forms an aqueous dispersion in which water is the continuous phase and the rubber particles produced in the polymerization are the dispersed phase.

[0017] For processing, the dispersion is introduced into a settling vessel. For transfer of dispersions from emulsion polymerization, a peristaltic pump is preferred if the dispersion storage tank does not provide sufficient gradient for pumpless gravity feed addition.

[0018] The solids content of the dispersion supplied to the precipitation vessel is preferably 10% to 50% by weight, more preferably 20% to 45% by weight, particularly preferably 30% to 40% by weight. The solids present in the dispersion are rubber in the form of particles.

[0019] In the precipitation vessel, the dispersion is converted into an aqueous suspension containing the rubber particles by adding a precipitation salt solution (preferably containing at least one salt and / or one acid).

[0020] In the present invention, a dispersion is understood to mean a mixture of particles having a volume-average particle size Dv in the range of 20 to 999 nm, preferably in the range of 50 to 800 nm, in a liquid phase. The volume-average particle size Dv (or average particle size according to De Broucker) is an average parameter based on a unit volume of the particles. The volume-average particle size of the particles in the dispersion can be determined by light scattering (laser diffraction), for example using a Beckman Coulter instrument.

[0021] A suspension is understood to be a mixture of particles in a liquid phase, the particles of which are larger than the particles of a dispersion. To determine the particle size of a suspension, for example, the D10 value, the D50 value or the D90 value can be used, depending on the type of determination of the particle size and particle size distribution, wherein the D10 value refers to the particle size of less than 10% by weight of the particles, correspondingly, the D50 value refers to the particle size of less than 50% by weight of the particles, and the D90 value refers to the particle size of less than 90% by weight of the particles. The particles in the suspension generally have a D10 value in the range of 50 to 400 μm, a D50 value in the range of 200 to 2000 μm, and / or a D90 value in the range of 500 to 4000 μm. The particles in the suspension particularly preferably have a D10 value in the range of 50 to 400 μm, a D50 value in the range of 200 to 2000 μm, and / or a D90 value in the range of 500 to 4000 μm.

[0022] The particle size of the suspension particles is preferably determined by wet sieving using a sieve tower containing sieves of different mesh sizes. After sieving, the weight of the particles on each sieve is measured, so that the D10 value, D50 value and D90 value can be obtained.

[0023] The precipitation solution preferably comprises a divalent or trivalent salt, and in particular the precipitation solution comprises at least one alkaline earth metal salt, preferably a magnesium salt and / or a calcium salt, particularly preferably at least one magnesium salt.

[0024] The at least one alkaline earth metal salt is particularly selected from alkaline earth metal halides (such as chlorides), alkaline earth metal sulfates, alkaline earth metal phosphates (such as orthophosphates or pyrophosphates), alkaline earth metal acetates and alkaline earth metal formates. Preferably, the at least one alkaline earth metal salt is selected from chlorides and sulfates.

[0025] Preferred alkaline earth metal salts are magnesium sulfate (e.g. magnesium sulfate monohydrate (Mg[SO4]·H2O), magnesium sulfate pentahydrate (Mg[SO4]·5H2O), magnesium sulfate hexahydrate (Mg[SO4]·6H2O) and Epsom salt (Mg[SO4]·7H2O)), magnesium chloride, calcium chloride, calcium formate, magnesium formate or mixtures thereof. Particular preference is given to using magnesium sulfate.

[0026] If the precipitation solution contains a trivalent salt, anhydrous aluminum sulfate or aluminum sulfate containing water of crystallization is particularly preferred.

[0027] The amount of salt added depends on the moisture content in the dispersion and is preferably in the range from 0.1 to 3% by weight, preferably in the range from 0.5 to 3% by weight, in particular in the range from 0.5 to 2% by weight, based in each case on the amount of water in the dispersion.

[0028] The pH value of the mixture of the dispersion obtained in step (a) and the precipitation solution is preferably in the range of 5-10, more preferably in the range of 6-9, especially in the range of 8-9.

[0029] The pH value can be adjusted, for example, by adding buffer salts, acids and / or bases, for example using sulfuric acid, phosphoric acid, sodium hydroxide solution, potassium hydroxide solution, sodium and potassium salts of carbonates (e.g. sodium carbonate Na2CO3 and / or sodium bicarbonate NaHCO3 or mixtures thereof), sulfates or phosphates (e.g. tetrasodium pyrophosphate).

[0030] Preferably, at least one buffer salt from the group of sodium salts, in particular a buffer salt selected from the group consisting of sodium carbonate, sodium sulfate and sodium phosphate, preferably a buffer salt selected from the group consisting of sodium carbonate Na2CO3 and sodium bicarbonate NaHCO3 is added.

[0031] The buffer salt, acid and / or base may have been added during the emulsion polymerization of the rubber or may have been mixed in the precipitation vessel in step (a). Preferably, the addition is carried out during the emulsion polymerization of the rubber.

[0032] In order to precipitate the rubber from the dispersion and obtain an aqueous suspension containing rubber particles, the precipitation solution and the dispersion are generally mixed for a period of 5 to 50 minutes, preferably 5 to 40 minutes.

[0033] The precipitation in step (a) can be carried out in a temperature range of 20° C. to 150° C., preferably 40° C. to 100° C., particularly preferably 45° C. to 99° C., likewise preferably 60° C. to 95° C. Preferably, the dispersion is mixed with the at least one precipitation solution at a temperature of 30° C. to 95° C., preferably 40° C. to 95° C., particularly preferably 40° C. to 90° C.

[0034] In order to obtain larger particles, the rubber particles in the aqueous suspension containing rubber particles obtained in step (a) may be aggregated so as to obtain larger particles in the subsequent sintering step (b). For this purpose, the aqueous suspension containing rubber particles obtained in step (a) is preferably transferred to a sintering container, in which the temperature of the aqueous suspension containing rubber particles is maintained in the range of 70° C. to 150° C., preferably in the range of 75° C. to 140° C., particularly preferably in the range of 85° C. to 140° C. The aqueous suspension containing rubber particles is maintained at this temperature for 10 to 90 minutes, preferably 15 to 90 minutes, particularly preferably 15 to 80 minutes.

[0035] It is particularly preferred that the mixing of the dispersion and the precipitation solution in step (a) is carried out at a temperature range of 30°C to 95°C, preferably at a temperature range of 40°C to 90°C, and if step (b) is carried out, the sintering in step (b) is carried out at a temperature range of 70°C to 120°C, preferably at a temperature range of 80°C to 100°C, for at least 5 minutes.

[0036] The precipitation of the rubber particles in step (a) and the sintering in step (b) can be carried out in different containers or in the same container, wherein carrying out the precipitation and sintering in the same container is possible, in particular when the process is a batch operation, because in this case, the initial mixing of the dispersion with the precipitation solution at a relatively low temperature is followed by sintering of the rubber particles at a relatively high temperature. Therefore, it is preferred to use a precipitation container in step (a) and a sintering container in step (b), wherein the sintering container and the precipitation container are two different containers. For conveying the aqueous suspension containing the rubber particles, the sintering container and the precipitation container are connected by a connecting pipe, which can accommodate a pump.

[0037] In order to obtain the most uniform particle size distribution of the resulting agglomerated particles during sintering, it is advantageous if both the precipitation of the rubber particles in the precipitation vessel and the sintering are carried out continuously.

[0038] In order to keep the suspension containing the rubber particles in motion and prevent the rubber particles from settling, in particular when the suspension cannot be supplied to subsequent plant components, for example due to downtime, the connecting pipe between the precipitation container and the sintering container is provided with a circulation loop, in which the aqueous suspension containing the rubber particles circulates.

[0039] For continuous operation, it is more advantageous to make the sintering vessel larger than the precipitation vessel if the desired residence time in the sintering vessel is greater than the residence time in the precipitation vessel.

[0040] After precipitation or, if step (b) is carried out, after sintering, the aqueous suspension containing the rubber particles is dewatered to obtain rubber particles containing residual water and a liquid phase containing finely divided rubber.

[0041] The moisture content of the rubber particles containing residual moisture is preferably not more than 60% by weight, more preferably not more than 50% by weight, and in particular not more than 40% by weight, in each case based on the total mass of the rubber particles containing residual moisture. The moisture content can be determined in particular using suitable analytical instruments, such as drying and weighing devices, in which the sample is dried until a constant weight is reached within a certain time. For example, the moisture content of the rubber particles containing residual moisture can be determined at 180° C. in a halogen moisture analyzer HR73 from Mettler Toledo until a constant weight is reached within 30 seconds.

[0042] The moisture content of the rubber granules containing residual moisture obtained in step (c) is in particular in the range from 10% to 50% by weight, preferably in the range from 20% to 45% by weight and in particular in the range from 20% to 40% by weight, in each case based on the total mass of the rubber granules containing residual moisture.

[0043] Mechanical dehydration is usually carried out by continuous or batch centrifugation and / or filtration. Mechanical dehydration is preferably achieved by continuous centrifugation. For this purpose, the aqueous suspension containing the rubber particles is centrifuged, for example, at a centripetal acceleration of 200·g to 2000·g, wherein the gravitational acceleration g=9.81 m / s 2 , preferably centrifuging at a centripetal acceleration of 500·g to 1300·g for a time of 1 second to 5 minutes, preferably 1 to 120 seconds.

[0044] In order to prevent the rubber particles from settling, in particular in the event of a malfunction of the continuously operating mechanical dewatering, it is also advantageous if the connection between the sintering container and the continuously operating mechanical dewatering, in particular at least one centrifuge or at least one filtering device, is provided with a circulation loop in which the suspension containing the sintered rubber particles can be temporarily stored before being fed to the centrifuge and / or filtering device. If a discontinuously emptied batch centrifuge is used, a buffer container is required to collect the suspension containing the rubber particles.

[0045] The rubber particles containing residual moisture can then be washed with water and / or a mixture of water and a polar, water-soluble solvent and then dried, for example as described in WO 2020 / 043690.

[0046] Since the liquid phase separated from the rubber particles containing residual water still contains finely divided rubber when the aqueous suspension containing rubber particles is mechanically dewatered, according to the invention, the liquid phase containing the finely divided rubber is recycled to a sedimentation vessel.

[0047] In order to buffer the variation in the output in each process step, it is preferred to collect the liquid phase containing the finely divided rubber in a recovery water container before returning it to the precipitation container. This also makes it possible to control the amount of the liquid phase containing the finely divided rubber mixed with the dispersion in the precipitation container, for example, to obtain a desired solid content in the mixture of the emulsion-polymerized dispersion and the liquid phase containing the finely divided rubber supplied to the precipitation container.

[0048] Since the amount of finely divided rubber in the liquid phase containing finely divided rubber is very low, usually not exceeding 2% by weight, especially in the range of 0.01% by weight to 1% by weight (based on the total mass of the liquid phase containing finely divided rubber), it is more preferred that the recovery water container is a sedimentation container forming a high rubber phase and a low rubber phase. The high rubber phase may be an upper phase or a lower phase, depending on the density of the rubber.

[0049] In order to prevent the liquid phase present in the recovery water container from being agitated and mixed by the introduction of a further liquid phase containing finely divided rubber obtained in the subsequent mechanical dewatering step, and also to prevent foaming in the recovery water container, the liquid phase containing finely divided rubber is preferably introduced into the recovery water container through a dip tube. This can prevent the initial high rubber phase and low rubber phase from mixing again, especially if the recovery water container is a sedimentation container.

[0050] The proportion of rubber in the high-rubber phase is high enough that the high-rubber phase from the recovery water container can be returned directly to the sedimentation container. The rubber content in the low-rubber phase is preferably not more than 0.5% by weight, more preferably in the range of 0.001% by weight to 0.1% by weight, in particular in the range of 0.001% by weight to 0.07% by weight, in each case based on the total mass of the low-rubber phase.

[0051] Since the water of the recovered high-rubber phase contains not only finely divided rubber but also dissolved salts and / or acids from the precipitation solution supplied to the precipitation vessel, it is more preferred that the high-rubber phase returned directly to the precipitation vessel is mixed with the precipitation solution also introduced into the precipitation vessel before introduction into the precipitation vessel.

[0052] Mixing the precipitation solution with the returning high-rubber phase before introduction into the precipitation vessel has the further advantage that the formation of undesirably large rubber particles due to locally high concentrations of precipitation solution and very rapid precipitation in the precipitation vessel can be prevented.

[0053] The salt content can be determined, for example, by conductivity measurement or titration, the acid content can be determined by pH determination, and the flow rate can be determined in each case by providing a suitable flow meter known to the person skilled in the art in the pipeline upstream of the mixing point. To adjust the desired concentration of salt and / or acid for precipitation, the mass flows of the supplied precipitation solution and the returned high-rubber phase are determined separately and the desired amount of precipitation solution is added using a ratio control device.

[0054] In order to recover the rubber from the low-rubber phase and not send it to disposal together with the wastewater, the low-rubber phase is preferably concentrated and then fed to a precipitation vessel. The wastewater formed during the concentration is sent to disposal, wherein the amount of wastewater preferably corresponds to the amount of water supplied with the dispersion and the precipitation solution minus the amount of water removed at other points in the process, in particular the water still present in the rubber particles containing residual moisture. This makes it possible to achieve a continuous process without constantly increasing the amount of water in the process due to the recovered water.

[0055] Any process known to the person skilled in the art for separating solids from solid-containing liquids can be used to concentrate the rubber particles present in the low-rubber phase. Very particularly preferably, the rubber particles are concentrated from the low-rubber phase by filtration. Filtration of the low-rubber phase produces a high rubber retentate and a filtrate that is substantially free of rubber, and the high rubber retentate is recovered in a precipitation vessel.

[0056] The filtration of the low rubber phase can be operated continuously. In this case, the liquid is pressed through the filter by the filtering device, thereby concentrating the low rubber phase. This forms a high rubber retentate, which is recycled in the sedimentation vessel, and the filtrate substantially free of rubber can be sent to be disposed of as waste water. The rubber content in the retentate can be adjusted by, for example, adjusting the volume flow through the filter, the pressure difference of the filter and / or the filter surface area. Only one filter or two or more filters can be used, wherein the filters can be connected in parallel and / or in series.

[0057] However, alternatively and preferably, the filtering operation is such that the rubber present in the low rubber phase is deposited as a filter cake on the filter of the filtering device and the liquid is withdrawn from the filter as a filtrate substantially free of rubber. In this case, the resulting filter cake is discontinuously rinsed into a sedimentation vessel with filtered recycled water.

[0058] Filters that can be used to concentrate rubber from a low-rubber phase include, for example, edge-split filters. Suitable filter materials include, for example, edge-split filters, wherein the filter separation size is preferably in the range of 10 to 500 μm, more preferably in the range of 50 to 250 μm, and particularly preferably in the range of 75 to 200 μm.

[0059] Filtration generally results in the solids being deposited on the filter, forming a filter cake. Depending on the volume flow of the low rubber phase through the filtration device, at least a portion of the filter cake can be flushed from the filter with the low rubber phase, where the rubber accumulates during the filtration process, and recovered with the retentate into the sedimentation vessel.

[0060] If a filter cake is formed which cannot be washed away with the retentate, the filter is preferably cleaned regularly. The time for cleaning the filter can be determined, for example, by the increase in the necessary pressure difference required to force the filtrate through the filter. Even if the filtration is carried out so that the rubber separates from the low-rubber phase to form a filter cake, the filter cake thus produced is cleaned regularly from the filter as described above, and the cleaning liquid in which the rubber is present is returned to the sedimentation vessel.

[0061] If the filters used do not require a positive pressure on the retentate side and / or a negative pressure on the filtrate side, the time required for cleaning the filter can also be determined by the filtrate volume flow or the solids content in the retentate.

[0062] The cleaning of the filter can be achieved by passing a cleaning liquid through the filter from the filtrate side to the retentate side, thereby cleaning the filter cake from the filter. Alternatively, the cleaning liquid can also be supplied to the filter instead of the low rubber phase. Since the filter cake mainly contains rubber, it is preferred to introduce the cleaning liquid containing the rubber from the filter cake into the sedimentation vessel. In order to enable the cleaning liquid containing the rubber present therein to be introduced into the sedimentation vessel, it is preferred to use such a cleaning liquid: it only contains components that are also present in the liquid in the sedimentation vessel. Therefore, it is particularly preferred to use water as the cleaning liquid.

[0063] The substantially rubber-free filtrate is removed from the process and preferably provided to wastewater treatment prior to discharge of the wastewater into the environment.

[0064] If the amount of liquid phase comprising finely divided rubber supplied to the recovery water container from the mechanical dewatering is greater than the amounts of high rubber phase and low rubber phase withdrawn from the recovery water container, resulting in the filling level in the recovery water container possibly exceeding the maximum filling level, the recovery water container preferably comprises an overflow opening from which the waste water flow can leave the recovery water container.

[0065] If the density of the rubber is lower than that of the liquid, it will float in the recovery water container, so that the high rubber phase is located in the upper region of the recovery water container. In this case, the overflow is preferably arranged in the lower region of the recovery water container, so that in the event that the filling level in the recovery water container exceeds the maximum filling level, ideally only the low rubber phase can be withdrawn. In order to allow the liquid to be discharged without providing an additional valve, it is therefore preferred that the pipe forming the overflow initially extends upwards to the height of the maximum filling level and comprises a bend of at least 90° there, so that the low rubber phase can be discharged from the overflow due to the hydrostatic pressure as soon as the maximum filling level has been reached.

[0066] If the density of the rubber is higher than the density of the liquid, the rubber will sink accordingly. In this case, the high rubber phase is located at the bottom of the recovery water container and the low rubber phase is located at the top, so that when the overflow is arranged in the upper region of the recovery water container, preferably at the location of the highest filling level, the low rubber phase will flow into the overflow when the filling level in the recovery water container becomes too high.

[0067] In particular, when a recovery water container is used in a dual-use device for producing both rubber having a lower density than the liquid and rubber having a higher density than the liquid, it is preferred to arrange an overflow at the top of the recovery water container (preferably at the position of the maximum filling level) and an overflow at the bottom of the recovery water container, wherein the overflow at the top of the recovery water container is closed when the density of the rubber is lower than the density of the liquid, and the overflow at the bottom of the recovery water container is closed when the density of the rubber is higher than the density of the liquid. It is more preferred if the overflow at the bottom is connected to the overflow at the top of the recovery water container by a conduit, wherein the conduit opens to the overflow downstream of the closing device, and the height of the opening of the conduit to the overflow is preferably the same as the connection of the overflow to the recovery water container.

[0068] As soon as the filling level in the recovery water container exceeds the maximum filling level, the high-rubber phase flows into the overflow. In order to prevent the high-rubber phase that subsequently flows into the overflow from entering the wastewater disposal and thus causing a loss of rubber in the high-rubber phase, in this case, it is preferred to provide a recovery pipe that branches off from the overflow and opens into the pipe through which the low-rubber phase flows for concentration, in particular filtration. This prevents the liquid that is still containing rubber from being sent for disposal and thus prevents the rubber present therein from being removed from the process as waste.

[0069] The pump for conveying the liquid phase containing the sintered rubber particles or (if no separate sintering step is carried out) the suspension containing the rubber particles obtained in step (a) to the mechanical dewatering preferably takes the form of a centrifugal pump configured as a vortex pump. The pump for conveying the low rubber phase to the filtration is preferably an eccentric screw pump.

[0070] The use of a centrifugal pump or an eccentric screw pump configured as a vortex pump allows conveying a liquid phase containing rubber particles without the pump being clogged by the rubber particles present in the liquid phase, since such a pump comprises a sufficiently large flow channel through which the liquid can pass without contacting the impeller of the pump.

[0071] In order to prevent the eccentric screw pump from wearing or clogging due to plastic expansion caused by any residual monomers, and thereby to be able to uniformly convey the liquid phase containing rubber particles, it is further preferred that the stator and / or rotor of the eccentric screw pump is made of chlorosulfonated polyethylene rubber (CMS), such as available from DuPont Performance Elastomers.

[0072] Since the rubber particles undergo further agglomeration and thus increase in size with increasing residence time, it is further preferred to be able to control the particle size of the rubber particles precipitated in step (a) and / or the particle size of the rubber particles sintered in step (b). For this purpose, for example, a pump including a cutting device for particle comminution can be used and / or a particle comminution device can be connected upstream of the pump.

[0073] Suitable particle comminution devices include, for example, wet mills through which a liquid phase containing rubber particles passes and which typically include a cutting device, wherein the cutting device may be fixedly included in the particle comminution device or may be configured as a rotor and a stator. Suitable particle comminution devices include, for example, Siefer machine.

[0074] For example, pumps comprising rotor-stator toothed mixing elements for comminuting particles are commercially available from BWS Technologie GmbH. Online homogenizer.

[0075] Exemplary embodiments of the invention are shown in the drawings and are explained in more detail in the following description and in the claims.

[0076] In the figure:

[0077] Figure 1 A flow chart of the method according to the present invention is shown;

[0078] Figure 2 is a schematic diagram of a recovery water container for rubber particles having a density higher than that of the liquid.

[0079] Figure 3 is a schematic diagram of a recovery water container for rubber particles having a density lower than that of the liquid,

[0080] Figure 4 is a schematic diagram of a recovery water container for a dual-use plant, in which rubber particles having a density lower than that of a liquid and rubber particles having a density higher than that of the liquid are produced alternately.

[0081] Figure 1 A flow chart of the method according to the present invention is shown;

[0082] For processing rubber from a rubber-containing dispersion, a rubber-containing dispersion 1, for example from an emulsion polymerization, is introduced into a precipitation vessel 5 together with a precipitation solution 3. The dispersion 1 is preferably conveyed to the precipitation vessel 5 only by gravity. If conveying by gravity is not possible, in particular if the dispersion tank in which the dispersion is temporarily stored is too low, the dispersion 1 is preferably conveyed into the precipitation vessel 5 using a peristaltic pump. In order to adjust the concentration in the precipitation vessel 5, water can also be additionally supplied via a line 6, either directly into the precipitation vessel 5 or into a line introducing the precipitation solution 3.

[0083] In the precipitation vessel, the rubber-containing dispersion 1 and the precipitation solution 3 are mixed with a mixing device 7 (e.g., a stirrer) to form an aqueous suspension containing rubber particles. The aqueous suspension 9 containing rubber particles is removed from the precipitation vessel and supplied to an optional sintering vessel 11, where the rubber particles aggregate to provide larger particles. In order to prevent the rubber particles from settling, the suspension containing rubber particles in the sintering vessel 11 is also mixed using a mixing device 13 (e.g., a stirrer).

[0084] In order to convey the aqueous suspension 9 containing rubber particles from the sedimentation vessel 5 into the sintering vessel 11, a first pump 15 is installed in the pipeline connecting the sedimentation vessel 5 and the sedimentation vessel 11. Preferably, the first pump 15 is part of a circulation loop 17, wherein, in particular in the event of a failure to pump out of the sintering vessel 11, for example in the event of a malfunction of a plant component downstream of the sintering vessel, the suspension 9 containing rubber particles is kept in motion, thereby preventing the particles from settling. The first pump 15 is preferably a centrifugal pump configured as a vortex pump.

[0085] The suspension 18 containing larger rubber particles is now supplied from the sintering container 11 to a mechanical dewatering 19. The mechanical dewatering 19 can be achieved, for example, by centrifugation or filtration, with centrifugation being preferred. In order to discharge the sintering container 11, a discharge pipe 20 is preferably provided at the bottom of the sintering container. In normal operation, the discharge pipe 20 is closed, and the aqueous suspension 18 containing larger rubber particles produced in the sintering container is extracted through the extraction pipe at the top of the sintering container 11.

[0086] In particular in the case of batch mechanical dewatering 19, the aqueous suspension containing rubber particles supplied to the mechanical dewatering 19 must be temporarily stored. For this purpose, a buffer container 21, for example, can be provided in which the aqueous suspension containing rubber particles 18 is temporarily stored. In order to prevent the rubber particles from settling out of the suspension, it is preferred that the buffer container 21 comprises a mixing device, for example a stirrer, with which the suspension can be stirred.

[0087] Alternatively, or in addition, it is further preferred to provide a second circulation loop 23 as shown in the figure, in which the aqueous suspension containing rubber particles can be circulated. The aqueous suspension containing rubber particles is mixed in the second circulation loop 23 to prevent the rubber particles from settling. The second circulation loop 23 is particularly advantageous when mechanical dehydration is continuously performed.

[0088] If the mechanical dewatering device 19 is operated continuously, it is sufficient to provide the second circulation loop 23 , although a buffer container 21 can also be connected upstream of the mechanical dewatering device 19 as an alternative or in addition.

[0089] If the mechanical dewatering device 19 is operated in batches, the buffer container 21 needs to temporarily store the suspension before it is supplied to the mechanical dewatering device 19. However, Figure 1 As shown, here too, a buffer container 21 can be connected upstream of the second circulation loop 23 .

[0090] In order to convey the aqueous suspension containing rubber particles from the sintering container 11 to the mechanical dewatering device 19 and to circulate in the second circulation loop 23, a second pump 25 is installed in the second circulation loop 23. Further preferably, a bypass 27 is provided so that the second pump 25 can be bypassed, wherein a third pump 29 is installed in the bypass 27.

[0091] As an alternative to the embodiment shown here, the second pump 25 and the third pump 29 can also be connected in series. This is particularly advantageous when the third pump 29 cannot build up a sufficiently high pressure relative to the second pump 25, because in this case a circulation flow from the pressure side to the suction side will be established.

[0092] Preferably, the second pump 25 and the third pump 29 are each a centrifugal pump configured as a vortex pump, similar to the first pump 15 .

[0093] Since the particles may further aggregate in the second circulation loop 23, it is more preferred if the second pump 25 and / or the third pump 29 are provided with a cutting device for crushing the particles. Using the cutting device, the particle size of the rubber particles can be adjusted to the desired size, and particles that reach an undesirable size due to aggregation will be crushed. In particular, when the suspension 18 containing rubber particles is conveyed directly to the mechanical dewatering 19, it is preferred that the second pump 25 and the third pump 29 are connected in series, wherein in this case, the second pump 25 preferably does not contain a cutting device and builds up the necessary pressure, and the third pump 29 with a cutting device is connected downstream of the second pump. If a buffer container 21 is present, no significant pressurization is required, and the second pump 25 and the third pump 20 can be operated in parallel.

[0094] As an alternative or in addition to the pump with cutting device, the second circulation loop 23 can also contain a particle crusher to prevent the formation of oversized rubber particles. The particle crusher is preferably a wet grinding device.

[0095] The sintering of the rubber particles in the sintering vessel 11 is usually carried out at a temperature higher than that of the mechanical dehydration 19. Therefore, it is preferred that a heat exchanger 31 is provided in the connecting pipe from the sintering vessel 11 to the mechanical dehydration 19 to cool the aqueous suspension containing the rubber particles.

[0096] If a second circulation loop 23 is provided between the sintering vessel 11 and the mechanical dewatering 19, the heat exchanger 31 is preferably located at a position in the second circulation loop 23 through which the aqueous suspension containing the rubber particles flows, even if the suspension is introduced directly from the sintering vessel 11 into the mechanical dewatering 19 and does not circulate in the second circulation loop 23. When a buffer vessel 21 is used, control of the temperature of the buffer vessel 21 can also be achieved by cooling, for example by a double jacket or cooling pipes running inside the buffer vessel.

[0097] In the mechanical dewatering, the rubber particles are separated from the aqueous suspension containing the rubber particles, and rubber particles containing residual moisture 33 and a liquid phase containing finely divided rubber 35 are obtained therein. The rubber particles containing residual moisture 33 are withdrawn from the process as raw material and supplied to an extruder to produce, for example, ABS or ASA.

[0098] The liquid phase 35 containing finely chopped rubber is introduced into a recovery water container 37. The recovery water container 37 is preferably a sedimentation container in which the finely chopped rubber in the liquid phase containing finely chopped rubber is accumulated, thereby forming a high rubber phase and a low rubber phase.

[0099] Preferably, the rubber portion in the high rubber phase 39 is large enough so that the high rubber phase can be directly withdrawn from the recovery water container 37 and recovered into the sedimentation container 5 .

[0100] In order to transfer the high rubber phase 39 from the recovery water container 37 to the sedimentation container 5, a pump 41 may be installed in the connecting pipe from the recovery water container 39 to the sedimentation container 5. However, it is preferred that the recovery water container 37 is located higher than the sedimentation container 5 so that the high rubber phase 39 can flow into the sedimentation container 5 purely under the action of gravity, thereby eliminating the need for the pump 41.

[0101] It is further preferred if the recovered high-rubber phase 39 is mixed with the precipitation solution 3 before introduction into the precipitation vessel 5 .

[0102] In order to obtain the rubber present in the low rubber phase 43 as a product and not send it to disposal with the wastewater, the low rubber phase 43 from the recovery water container 37 is supplied to the filtration 45. The filtration 45 concentrates the rubber in the low rubber phase to form a high rubber retentate 47, which is introduced into the sedimentation container 5.

[0103] If the filtration 45 is carried out so that a filter cake is formed on the filter in the filtration device, the filter cake is preferably rinsed off regularly and the washing liquid in which the rubber is present is introduced as a high rubber retention 47 into the precipitation container 5. In order not to introduce any unwanted components into the precipitation container 5, backwashing is preferably carried out with water, in particular completely deionized water 49. Alternatively, backwashing can also be carried out with the filtrate 51.

[0104] The pore size of the filter used for filtering 45 is preferably selected so that substantially all of the finely divided rubber present in the low rubber phase is separated to form a substantially rubber-free filtrate 51 which can be discharged as wastewater and supplied to wastewater treatment and then sent for disposal.

[0105] The low rubber phase 43 is preferably conveyed to the filtration 45 using a fourth pump 53. Any pump capable of conveying only a liquid phase containing a low solid content may be used here.

[0106] Suitable pumps include, for example, centrifugal pumps or eccentric screw pumps. When an eccentric screw pump is used, it is particularly preferred that the stator and / or the rotor of the eccentric screw pump is made of chlorosulfonated polyethylene rubber (CMS).

[0107] Figure 2 There is shown a recovered water container 37 which is configured as a sedimentation container in the first embodiment.

[0108] The liquid phase 35 containing finely chopped rubber is supplied to the recovery water container 37 through the dip tube 55. The supply of the liquid phase 35 containing finely chopped rubber through the dip tube 55 prevents the upper region of the recovery water container 37, which contains a rubber-depleted phase, from being enriched with rubber due to the liquid phase 35 containing finely chopped rubber. At the same time, the flow of the liquid phase 35 containing finely chopped rubber into the bottom region ensures that the precipitated rubber does not form a sediment in the bottom region of the recovery water container 37. In this way, even if the liquid phase containing finely chopped rubber is introduced into the recovery water container 37 continuously or at corresponding regular intervals in the case of batch mechanical dehydration, the recovery water container 37 can be used as a sedimentation container.

[0109] The rubber present in the liquid phase containing the finely chopped rubber is collected in the recovery water container 37 configured as a sedimentation container, thereby forming a high rubber phase and a low rubber phase. If the density of the rubber is higher than the liquid of the liquid phase containing the finely chopped rubber, the rubber sinks, with the result that the high rubber phase is located at the bottom and the low rubber phase is located at the top. Therefore, when the density of the rubber is lower than the density of the liquid of the liquid phase containing the finely chopped rubber, the rubber floats, with the result that in this case the high rubber phase is located at the top and the low rubber phase is located at the bottom.

[0110] When the density of the rubber is higher than the density of the liquid, it is particularly preferred to use Figure 2 The recovery water container in the embodiment shown. In this case, the dip tube 55 preferably ends near the bottom 57 of the recovery water container 37, so that the newly supplied liquid phase containing finely divided rubber is supplied to the lower region of the high rubber phase. This achieves mixing of the high rubber phase with the newly supplied liquid phase containing finely divided rubber near the bottom 57 of the recovery water container 37, thereby minimizing the amount of rubber that settles and can form a covering on the bottom 57 of the recovery water container 37.

[0111] The high-rubber phase formed in the lower region of the recovery water container 37 is preferably drawn off via an overflow 59 at the bottom 57 of the recovery water container and fed to the sedimentation container 5 .

[0112] The low-rubber phase forms the upper phase in the sedimentation container and is preferably drawn off via an overflow 61 in the upper region of the recovery water container 37 and fed to the filter 45, optionally via a pump 53. It is particularly preferred when the overflow 61 of the low-rubber phase is arranged at a height corresponding to the desired maximum filling height 63.

[0113] The overflow 65 is provided to prevent the recovery water container 37 from being overfilled, especially when the amount of liquid phase containing finely chopped rubber supplied to the recovery water container 37 is greater than the amount of high rubber phase and low rubber phase extracted from the recovery water container through the overflows 59 and 61. Since the low rubber phase is located in the upper region of the recovery water container 37, only a very small amount of rubber is extracted from the recovery water container 37 by the extraction through the overflow 65, thereby ensuring very low product losses. The low rubber liquid discharged through the overflow 65 is then usually supplied to wastewater treatment so that the wastewater can be discharged to the environment after treatment.

[0114] Figure 3 A recovery water container 37 is shown in a second embodiment, which is preferably used when the density of the rubber is lower than the density of the liquid containing the liquid phase of the finely divided rubber, resulting in the rubber floating in the recovery water container and forming a high rubber phase on the top and a low rubber phase on the bottom.

[0115] and Figure 2 Unlike the recovery water container shown, in the case of a recovery water container using a process in which a high rubber phase is formed at the top of the recovery water container 37, the dip tube 55 has terminated in the middle area of ​​the recovery water container, so that the rubber supplied from the liquid phase containing finely chopped rubber introduced through the dip tube 55 rises, and as a result, enters the recovery water container 37 above the opening of the dip tube 55 to form a high rubber phase, while a low rubber phase is formed below the opening of the dip tube 55.

[0116] The high-rubber phase is thus drawn off through the overflow 67 in the upper region of the recovery water container 37, wherein here too the overflow 67 is preferably arranged at the location of the desired maximum filling height 63. The high-rubber phase is thus discharged from the recovery water container 37 in the region of the phase interface, in which region the maximum rubber content is found with the rubber rising. The rubber proportion in the low-rubber phase is therefore lowest at the bottom 57 of the recovery water container 37, and the low-rubber phase is therefore drawn off through the overflow 69 at the bottom 57 of the recovery water container 37.

[0117] In addition, Figure 3In the embodiment shown, the recovery water container 37 comprises an overflow 65 to prevent the recovery water container 37 from being overfilled. Since, in the case of lightweight rubber, the low rubber phase is located in the lower region of the recovery water container 37, the overflow 65 branches off from the overflow 69 at the bottom 57 of the recovery water container 37 and preferably extends upwards outside the recovery water container 37 to the height of the maximum filling level in the recovery water container. At the height of the maximum filling level, the overflow 65 has a curvature of at least 90° so that the liquid can flow horizontally or downwards again after the curvature. The curvature represents the highest point of the overflow. This allows the low rubber phase to leave the recovery water container 37 after reaching the maximum filling level without any additional closing device.

[0118] Figure 4 A recovery water container 37 is shown which can be used in a dual-purpose plant which alternately produces rubber having a density lower than the liquid density of the liquid phase containing finely divided rubber and rubber having a density higher than the liquid density of the liquid phase containing finely divided rubber.

[0119] In order to avoid the need to use two different recovery water containers in a dual-use plant, depending on the density of the rubber produced, Figure 2 and 3 Unlike the embodiment shown in , the recovery water container 37 that can be used in the dual-use device includes: an overflow 65 that branches at the position of the maximum filling level and can be closed by a first closing device 71A; and a pipeline 73 that branches from the outflow 69 at the bottom 57 of the recovery water container and can be closed by a second closing device 71B, and the pipeline opens to the overflow 65 downstream of the first closing device 71A, and the overflow 65 also branches from the recovery water container 37 and is at the same height. The closing devices 71A, 71B can be, for example, valves, cocks or slides independently of each other.

[0120] When the density of the produced rubber is higher than the liquid density of the liquid phase containing the finely divided rubber, the first shut-off device 71A is opened and the second shut-off device 71B is closed. Thus, when the maximum liquid level is exceeded, the low rubber phase can leave the recovery water container 37 through the overflow port 65. Since the high rubber phase is collected in the lower region of the recovery water container 37, the high rubber phase is drawn out of the recovery water container 37 through the outflow port 69. The low rubber phase can be drawn out of the recovery water container 37 through the outflow port 67.

[0121] Accordingly, when a rubber having a density lower than that of the liquid phase containing the finely divided rubber is used, the first shut-off device 71A is closed and the second shut-off device 71B is opened. In this case, exceeding the maximum filling level causes the low rubber phase to flow into the overflow 65 through the pipe 73. The high rubber phase is withdrawn through the overflow 67 in the upper region of the recovery water container 37, while the low rubber phase is withdrawn through the overflow 69.

[0122] Since, depending on the density of the rubber produced, the high rubber phase is drawn off through the overflow 67 in the upper region of the recovery water container 37 or the overflow 69 at the bottom 57 of the recovery water container 37, and the low rubber phase is drawn off through the other overflow 69, 67, respectively, the overflow 67, 69 for drawing off the high rubber phase is connected to the device in each case so that the high rubber phase enters the sedimentation container 5, while the overflow 67, 69 for drawing off the low rubber phase is connected to the filter 45. This can be achieved, for example, using a 3 / 2-way valve, in which the inlet is connected to the overflow 67, 69, one of the outlets is connected to the pipe leading to the sedimentation container 5, and the other outlet is connected to the pipe leading to the filter 45. Alternatively, the respective pipe leading to the sedimentation container 5 or the filter 45 can also be connected to the respective overflow 67, 69. This can be achieved, for example, by a hose connected to the respective overflow 67, 69 via a joint.

[0123] Examples

[0124] All examples and comparative examples used aqueous dispersions containing butyl acrylate grafted rubber (hereinafter referred to as dispersions). The average particle size of the butyl acrylate grafted rubber in the dispersion was 95 nm, and the proportion of the grafted rubber in the dispersion was 35% by weight.

[0125] All examples and comparative examples are Figure 1 The post-processing device shown in FIG. 1 is carried out without the buffer container 21 and has Figure 2 A recovery water container 37 is shown.

[0126] The temperature in the precipitation vessel 5 was maintained at 60° C., where the temperature was regulated by direct supply of steam. The resulting suspension was transferred from the precipitation vessel via a circulation loop 17 to the sintering vessel 11, where the temperature was maintained at 92° C. The pump 15 in the circulation loop 17 was operated at 11 m / s. 3 The second circulation loop 23 supplies the suspension obtained in the sintering vessel 11 to the continuously operated push rod centrifuge 19 for mechanical dehydration. The flow rate in the circulation loop 23 is 85 m / s. 3 The continuously operated push rod centrifuge 19 and the filter in the filter 45 both have a separation size of 100 μm.

[0127] Comparative Example 1

[0128] 1.4m 3 / h dispersion, 160kg / h 14% magnesium sulfate solution and 1.9m 3 / h of deionized water is introduced into the precipitation vessel. Neither the retentate obtained in the filter 45 nor the high rubber phase 39 obtained in the recovery water vessel is recovered into the precipitation vessel.

[0129] 2.8m 3 / h of rubber-containing phase leaves the recovery water container and is directly discharged as wastewater. The amount of rubber lost through wastewater discharge is 2.8 kg / h. In addition, the amount of magnesium sulfate discharged through wastewater is 22 kg / h.

[0130] Comparative Example 2

[0131] To reduce the loss via wastewater, the concentration in the precipitation vessel was increased by reducing the amount of deionized water added. In Comparative Example 2, neither the retentate obtained in the filter 45 nor the high rubber phase obtained in the recovery water vessel was recovered to the precipitation vessel.

[0132] 1.4m 3 / h dispersion, 160kg / h 14% magnesium sulfate solution and 0.9m 3 / h of deionized water is introduced into the precipitation container.

[0133] Now only 1.5m 3 / h of liquid leaves the recovery water container as waste water. 1.5 kg / h of rubber is lost through the waste water, and 12 kg / h of magnesium sulfate is discharged through the waste water.

[0134] Example 1

[0135] Unlike the comparative example, both the high rubber phase 39 and the retentate 47 obtained in the filter 45 are recovered to the sedimentation vessel.

[0136] For this example, also 1.4m 3 / h of dispersion was introduced into the precipitation vessel. The amount of 14% magnesium sulfate solution supplied was 51.4 kg / h.

[0137] 1.9m 3 / h of high rubber phase 39 is recovered from the recovery water container to the sedimentation container, and the amount of the recovered retentate 47 is 50 kg / h, wherein it is introduced discontinuously into the sedimentation container.

[0138] The amount of the filtrate 51 extracted as waste water from the filter 45 is 0.7 m 3 No rubber losses were detected and the amount of magnesium sulfate discharged from the process via the filtrate was 5.5 kg / h.

[0139] It has thus been found that the process according to the invention can maximise the yield of rubber, as no rubber is withdrawn from the process with the wastewater, and can also minimise the amount of magnesium sulphate removed from the process with the wastewater.

[0140] Therefore, the provided method is also improved from an environmental point of view.

Claims

1. A method for processing rubber from a dispersion (1) containing rubber, the method comprising: (a) providing a dispersion (1) containing rubber and a precipitation solution (3) to a precipitation vessel (5) to obtain an aqueous suspension (9) containing rubber particles, (b) optionally sintering the rubber particles present in the aqueous suspension containing the rubber particles (9) to obtain larger particles, (c) mechanically dehydrating the aqueous suspension (9) containing rubber particles to obtain rubber particles (33) containing residual water and a liquid phase (35) containing finely divided rubber, The method is characterized in that the liquid phase (35) containing the finely divided rubber is recycled to the precipitation vessel (5).

2. The method according to claim 1, characterized in that The liquid phase (35) containing the finely divided rubber is collected in a water recovery container (37).

3. The method according to claim 2, characterized in that The liquid phase (35) containing the finely chopped rubber is introduced into the recovery water container (37) through the dip tube (55).

4. The method according to claim 2 or 3, characterized in that: The recovery water vessel (37) is a sedimentation vessel in which a high rubber phase (39) and a low rubber phase (43) are formed.

5. The method according to claim 4, characterized in that The high rubber phase (39) is recovered directly to the precipitation vessel (5).

6. The method according to claim 4, characterized in that The high rubber phase (39) is mixed with the precipitation solution (3) and then introduced into the precipitation vessel (5).

7. The method according to any one of claims 4 to 6, characterized in that The low rubber phase (43) is concentrated and then recycled to the precipitation vessel (5).

8. The method according to claim 7, characterized in that The low rubber phase (43) is concentrated by filtration to obtain a high rubber retentate (47) and a substantially rubber-free filtrate (51), and the high rubber retentate (47) is recovered to a precipitation vessel (5).

9. The method according to claim 8, characterized in that The high rubber retentate (47) is collected as a filter cake in the filter and passes into the sedimentation vessel (5) together with the cleaning liquid (49).

10. The method according to any one of claims 2 to 9, characterized in that The waste water stream can flow out of the recovery water container (37) through the overflow.

11. The method according to any one of claims 1 to 10, characterized in that A centrifugal pump configured as a vortex pump is used to convey the aqueous suspension (9) containing rubber particles from step (a) or the suspension containing larger rubber particles from step (b).

12. The method according to any one of claims 4 to 11, characterized in that An eccentric screw pump is used to convey the low rubber phase (43).

13. The method according to claim 12, characterized in that The stator and / or rotor of the eccentric screw pump is made of chlorosulfonated polyethylene rubber.

14. The method according to any one of claims 11 to 13, characterized in that The centrifugal pump configured as a vortex pump comprises a cutting device for particle comminution and / or the eccentric screw pump or the centrifugal pump configured as a vortex pump has a particle comminution device arranged upstream thereof.

15. The method according to any one of claims 1 to 13, characterized in that The rubber is butyl acrylate grafted rubber or butadiene grafted rubber.

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