Process for obtaining low volatile plastomers

Abstract

A process for reducing the volatile organic compound content of a plastic mass to below 65 ppm (VOC, VDA 277), the plastic mass having a density equal to or below 883 kg / m 3 and a MFR2 (ISO 1133 at 2.16 kg load and 190°C) of 100.0 g / 10 min or lower; the process comprising the steps of: a) providing a raw plastic mass in particulate form, the raw plastic mass having a density equal to or below 883 kg / m 3 and a MFR2 (ISO 1133 at 2.16 kg load and 190°C) of 100.0 g / 10 min or lower; and a volatile organic compound content (VOC, VDA 277) of above 150 ppm, and particles having an average D50 diameter of 2.5 mm to 4.5 mm; b) subjecting the particulate raw plastic mass to at least one intensified hydrodynamic system at a minimum temperature of at least 20°C and a maximum temperature of 4°C lower than the Vicat temperature (10 N, ISO 306) of the particulate raw plastic mass or the lower value of 35°C, wherein the intensified hydrodynamic system is a fluidized bed system, wherein the superficial gas flow rate is above the minimum fluidization velocity and the superficial gas flow rate is at least 40 cm / s, the temperature being measured at the gas inlet of the fast fluidization system, c) recovering the particulate plastic mass.

Description

[0001] This application is a divisional application of patent application no. 201980006143.4 filed on January 15, 2019 with the title “Method for obtaining a low volatile plastic mass”. TECHNICAL FIELD

[0002] The present invention relates to a method for obtaining a plastic mass having a low volatile organic compound (VOC) content and to a method for reducing the volatile organic compound content of a granular plastic mass to below 65 ppm (VOC, VDA 277). BACKGROUND

[0003] The removal of volatile organic compounds from plastic masses is challenging due to the limited temperature window caused by the inherent tackiness of volatile organic compounds and the tendency to agglomerate at temperatures above a relatively low temperature, and is particularly challenging for plastic masses produced in solution polymerization due to the relatively high VOC content. Various attempts have been made to address these issues. Typically, hydrocarbons are purged from the plastic mass obtained by solution polymerization in one or more flash columns. Frequently, a purge column (or de-aeration bin) using an inert gas stream and / or a steam dryer using water vapor are optionally and additionally used for separating hydrocarbons.

[0004] EP 735 053 relates to a method for stripping oligomers from finely dispersed, essentially crystalline alpha-olefin polymer particles in a fluidized bed and at a temperature which avoids agglomeration of the fine particles. EP 735 053 particularly relates to the handling of particles of such polymer (commonly referred to as flakes having an average particle size of 0.25 mm to 2.00 mm). Exemplary temperatures of 100 °C to 140 °C and treatment times of 1 hour to 3 hours are given. In another aspect, EP 735 053 considers reducing the concentration of oligomers to below 250 ppm to have no any effective action.

[0005] WO 93 / 13843 relates to a method for removing hydrocarbons from a polymer slurry obtained by solution polymerization comprising flash separation as a first stage, further treatment of the slurry in a fluidized bed dryer with heated hydrocarbons as stripping gas as a second stage. The resulting polymer is then transferred from the fluidized bed dryer to a bin where additional hydrocarbons are removed by using a heated purge gas stream countercurrent to the polymer as a third stage. Finally, the polymer product is subjected to further processing such as extrusion into granules.

[0006] US 5,326,855 particularly relates to a method for treating rubber compounds in a fluidized bed dryer.

[0007] Reducing the VOC of a plastomer to very low levels, such as below 65 ppm, is still time consuming and has significant limitations in terms of the total time required. In addition to those, processing the polymer particles in the silo under packed bed conditions still creates a non-uniformity in the volatile concentration of the individual particles, meaning that a significant VOC distribution still exists in the individual particles.

[0008] Therefore, there is still a need for an improved method for enabling a higher efficiency, in particular a reduction of the processing time, for removing volatiles from a plastomer at a reasonably low temperature. There is also a need for having a more uniform VOC distribution in the individual particles of a granular plastomer. SUMMARY

[0009] The present invention is based on the finding that the volatile content of a plastomer having a density equal to or below 883 kg / m 3 and having a MFR2 (ISO 1133 at 2.16 kg load and at 190 °C) of 100 g / 10 min or below, starting with a volatile organic compound (VOC, VDA 277) content above 150 ppm, can be effectively reduced by providing the plastomer in the form of particles having an average D50 particle size of 2.5 mm to 4.5 mm and subjecting the granular particles to a fast-fluidization regime at a maximum temperature of a temperature of up to 4 °C below the Vicat temperature (10 N, ISO 306) of the granular raw material plastomer or a lower value of 35 °C, wherein the fast-fluidization regime is a fluidized bed system in which the superficial gas velocity is above the minimum fluidization velocity and the superficial gas velocity is at least 40 cm / s.

[0010] The present invention in particular provides a method for reducing the volatile organic compound content of a plastomer to below 65 ppm (VOC, VDA 277), the plastomer having

[0011] - a density equal to or below 883 kg / m 3 , and

[0012] - a MFR2 (ISO 1133 at 2.16 kg load and 190 °C) of 100.0 g / 10 min or below;

[0013] The method comprises the steps of

[0014] a) providing a raw material plastomer in the form of particles, the raw material plastomer having

[0015] - a density equal to or below 883 kg / m 3 ; and

[0016] - MFR2 (ISO 1133 at 2.16 kg load and 190 °C) of 100.0 g / 10 min or lower;

[0017] - volatile organic compounds content (VOC, VDA 277) higher than 150 ppm; and

[0018] - particles having an average D50 diameter of 2.5 mm to 4.5 mm,

[0019] b) subjecting the particulate raw plastic mass to at least one intensive hydrodynamic regime at a minimum temperature of at least 20 °C and a maximum temperature of 4 °C lower than the Vicat temperature (10 N, ISO 306) of the particulate raw plastic mass or the lower value of 35 °C, the temperature being measured at the gas inlet of the intensive hydrodynamic regime, wherein the intensive hydrodynamic regime is a fluidized bed system, wherein the superficial gas velocity is higher than the minimum fluidization velocity and the superficial gas velocity is at least 40 cm / s,

[0020] c) recovering the particulate plastic mass.

[0021] In another aspect, the present application relates to the use of the process of the present application for homogenizing the concentration of volatiles in the obtained particles. The present application further relates to the use of the process according to the present application for minimizing the processing time when reducing the volatile organic compounds content (VOC, VDA 277) of a raw plastic mass having a volatile organic compounds content (VOC, VDA 277) higher than 150 ppm to less than 65 ppm (VOC, VDA 277) for the resulting plastic mass. DETAILED DESCRIPTION

[0022] DEFINITIONS

[0023] The volatile organic compounds content (VOC, VDA 277) is a measure for emissions from plastic materials, such as low density plastic masses caused by low molecular components in the polymeric material. These low molecular components can be residual monomers, oligomers, additives, plasticizers and / or degradation products.

[0024] The term particulate, such as used herein, means a plastic mass in the form of a pellet and / or a granular material. For example, the pellets can be formed by forcing a plastic mass melt through a die and subsequently granulating it with an underwater pelletizer.

[0025] The plastic mass, such as used herein, is an ethylene alpha-olefin copolymer which combines the properties of an elastomer and a plastic, i.e. it has rubber-like properties and plastic processability.

[0026] The term "enhanced hydrodynamics system" is different from a packed bed. The term "enhanced hydrodynamics system" requires a superficial gas flow rate higher than the minimum fluidization velocity.

[0027] By definition, a "slugging regime" shall meet the criteria set by Stewart and Davidson, incorporated herein by reference (Stewart, P. S. B., & Davidson, J. F. (1967). Slug flow in fluidized beds. Powder Technology, 1, 61.).

[0028] A "double cone regime" denotes the presence of a turbulent bed and of a lower and an upper cone geometry of the processing vessel. Such geometries are described inter alia in WO-A-2014032794, EP-A-2913346, EP-A-2913345, EP-A-3184166 and EP-A-3184167.

[0029] DETAILED DESCRIPTION

[0030] It was surprisingly found that a reduction of VOCs in the plastic mass is effectively achieved by using a granular plastic mass having an average D50 particle size between 2.5 mm and 4.5 mm (measured according to the method described herein) as starting material under an enhanced hydrodynamics system. It was previously thought that the best reduction of volatiles or similar substances should be obtained directly from the polymer using a reactor in the form of flakes having an average particle size below 2 mm, i.e. small polymer particles which do not undergo a compounding step. However, the inventors of the present application surprisingly found that the concentration of volatiles in a granular plastic mass having an average D50 particle size between 2.5 mm and 4.5 mm (i.e. substantially larger dimensions than flakes) is surprisingly good when applying the method of the present application. In another aspect, the method of the present application proves to result in a significant time saving when compared to a conventional aeration method applying granulation as a last step after processing in an enhanced hydrodynamics system or aeration of a packed bed.

[0031] In the method according to the present application, the granular starting plastic mass has an average D50 particle size between 2.5 mm and 4.5 mm measured according to the method described herein.

[0032] The granular starting plastic mass is provided in a processing vessel. In its simplest form, it can be any vessel or tube allowing to provide an enhanced hydrodynamics system. Typically, the processing vessel will be a conventional gas phase reactor. When the enhanced hydrodynamics system is a double cone regime, such processing vessel is additionally characterized by a double cone geometry, i.e. having a bottom cone and a top cone.

[0033] The granular raw plastic mass according to the present application has an MFR2 of 100 g / 10 min or less, preferably 20 g / 10 min or less and even more preferably 6 g / 10 min or less.

[0034] The granular plastic mass has a density of 883 kg / m3 or less, more preferably 870 kg / m3 or less. 3 3

[0035] The temperature measured at the gas inlet of the intensified hydrodynamic system according to the present application has a minimum temperature of at least 20 °C. In addition, the maximum temperature is a temperature of 4 °C less than the Vicat temperature (10 N, ISO 306) of the granular plastic mass or the lower value of 35 °C. Thus, if the Vicat temperature (10 N, ISO 306) of the granular plastic mass is 38 °C, the temperature must not exceed 34 °C. However, if the Vicat temperature (10 N, ISO 306) of the granular plastic mass is 40 °C or even 45 °C, the maximum temperature is 35 °C. Preferably, the maximum temperature is 32 °C, more preferably 31 °C. The minimum temperature is preferably 27 °C and more preferably 28 °C, most preferably 30 °C.

[0036] Preferably, the gas is injected via a gas distribution plate for the fluidization system and the surge system. When a double cone system is desired, it is preferred that no gas distribution plate is used and the gas is injected via nozzles from the bottom cone.

[0037] Preferably, the raw plastic mass according to the present application is produced in a solution polymerization process. It is per se conceivable that also raw plastic masses with other processing histories can be processed. However, usually such raw plastic masses do not contain undesired high amounts of VOCs.

[0038] In another aspect, the plastic mass according to the present application is preferably a copolymer of ethylene and 1-octene. It is known that a part of copolymers of ethylene and 1-octene are very viscous and have a high tendency to agglomerate, making the post-reactor processing steps difficult.

[0039] ​​The intensified hydrodynamic system is a fluidized bed system. When the gas flow rate through a fixed bed is increased, the superficial gas flow velocity will reach a critical value representing the minimum fluidization velocity, which is well known in the art. The intensified hydrodynamic system is especially a fluidized bed system. At minimum fluidization, the bed can be considered as a pseudo-liquid. Further increase of the gas flow can result in bubble formation. Bubbles are gas voids with little or even no inclusion of solids. This results in solids moving in upward direction to a certain height. Increase of the fluidization velocity for a given bed results in an increase of the bubble size. If the cross section of the bed is relatively small, the bubble size can almost reach the diameter of the bed. If this is the case, relatively large bubbles will pass through the bed as slugs. The criteria for slug formation are well known in the art. Reference is made to Stewart, P.S.B., & Davidson, J.F. (1967). Slug flow in fluidized beds. Powder Technology, 1, 61. The intensified hydrodynamic system is especially a slug system.

[0040] When the flow rate of the gas is further increased and at the same time a double cone geometry is used for the process vessel, a specific turbulent bed will be created, representing a "double cone system". The cone geometry at the bottom of the process vessel and especially the cone geometry at the top of the process vessel will guarantee a significant particle migration and a high gas flow rate near the inner surface of the process vessel between the cones.

[0041] In the process according to the present application, the superficial gas flow velocity is at least 40 cm / s. In a slug system, the superficial gas flow velocity will be at least 60 cm / s and in a double cone system the superficial gas flow velocity is at least 90 cm / s.

[0042] The process according to the present application can be run intermittently or continuously. Continuous mode means that the process vessel is not completely emptied and the process is stopped. Continuous mode means production as opposed to intermittent production. In continuous mode, the process is only stopped at infrequent maintenance shutdowns. Usually, the process will be run intermittently.

[0043] In the process according to the present application, the gas used in the fast fluidization system is selected from the group of nitrogen, air and mixtures thereof. For commercial reasons, the use of air is preferred.

[0044] In another aspect, the process vessel used in the present invention is an adiabatic process vessel. Preheating of the raw granular plastic mass can be used if required due to the environment, such as low ambient temperature. Generally, preheating of the raw granular plastic mass will reduce the aeration time. Preheating is especially preferred. Preheating means subjecting the granular raw plastic mass to an intensified hydrodynamic system using a method for heating instead of at a minimum temperature of at least 20 °C and a temperature of 4 °C lower than the Vicat temperature (10 N, ISO 306) of the granular raw plastic mass or a maximum temperature of 35 °C or lower, the temperature being measured at the gas inlet of the fast fluidization system.

[0045] In the process according to the present invention, the entrainment from the intensified hydrodynamic system is preferably minimized by using at least one gas-solid separator, preferably a cyclone. However, the inventors of the present invention have also found that due to the large particle size, the solids entrainment rate is a weak function of the superficial velocity.

[0046] In a first preferred embodiment of the present invention, the volatile organic compound content of the granular plastic mass is reduced in the process to 20 ppm or less, preferably to 15 ppm or less, and most preferably to 10 ppm or less. The aim of this embodiment is to have a plastic mass with as low an amount of volatile organic compounds as possible. The process time of the first preferred embodiment depends on the starting material and the target VOC content as well as the process conditions.

[0047] In the process of the first preferred embodiment of the present invention, when starting from a raw plastic mass having a VOC content of 1000 ppm, the process time is less than about 12 hours when using a double cone system and about less than 48 hours when using a fluidized bed system.

[0048] In a second preferred embodiment of the present invention, the volatile organic compound content of the granular plastic mass is reduced in the process to 65 ppm or less, preferably to 60 ppm or less, and most preferably to 55 ppm or less. Generally, the volatile organic compound content of the granular plastic mass of this embodiment will be higher than 20 ppm. This embodiment aims at achieving a plastic mass with a reasonable amount of volatile organic compounds in an advantageous short process time. This embodiment especially aims at a balance of reducing volatile organic compounds and total process costs. In the process of the second preferred embodiment of the present invention, when starting from a raw plastic mass having a VOC content of 1000 ppm, the process time is less than about 3 hours for a double cone system and about less than 24 hours for a fluidized bed system.

[0049] The preparation of the plastic mass for use in the present invention is especially described in EP 3 023 450, which is incorporated herein by reference.

[0050] The present invention further relates to an integrated process. In this integrated process, the raw plastomer is produced in a solution polymerization process, the integrated process further comprising the following steps:

[0051] (i) subjecting the polymer slurry directly obtained from the solution polymerization reactor to a first separation stage using at least one flash separation, resulting in a first intermediate polymer;

[0052] (ii) subjecting the first intermediate polymer to an extruder to form a particulate raw plastomer, the particles having an average D50 diameter of 2.5 mm to 4.5 mm.

[0053] It is particularly important and most preferred in the above integrated process that the step of extruding the particulate raw plastomer resulting in particles having an average D50 diameter of 2.5 mm to 4.5 mm precedes the step of subjecting the raw plastomer to at least one intensified hydrodynamic system. In other words, the intermediate polymer in non-solidified form (e.g. in flake form) does not need to be subjected to an intensified hydrodynamic system.

[0054] Flash separation is well known in the art and involves a significant pressure reduction for the removal of by-products and reactants such as hydrocarbons.

[0055] In the integrated process according to the present invention, the particles of the raw plastomer and / or the particles of the plastomer recovered from the at least one intensified system can be subjected to a purge column and / or a steam drier. A purge column denotes a bin in which the treated substrate is subjected to a stream of an inert gas such as nitrogen for the further removal of by-products and reactants such as hydrocarbons. Steam driers are also well known in the art and use water vapor for the same further removal of by-products and reactants such as hydrocarbons.

[0056] The present invention further relates to a particulate plastomer obtainable by the above process. In conventionally produced particulate plastomers, there is a large gradient in the amount of volatiles shown by the individual particles. As expected, in conventionally produced particulate plastomers, the amount of volatiles is essentially zero close to the surface and quite high at a large distance from the surface. The present invention allows for a better distribution.

[0057] The present invention especially further relates to the use of the process of the present invention for homogenizing the concentration of volatiles in the obtained particles.

[0058] In yet another aspect, it is an object of the present invention the use of the process of the present invention for minimizing the processing time when reducing the volatile organic compound content (VOC, VDA 277) of a raw plastomer having a volatile organic compound content higher than 150 ppm to less than 65 ppm (VOC, VDA 277) for the produced plastomer.

[0059] Experimental part

[0060] Test method

[0061] a) MFR

[0062] The melt flow rate (MFR) is determined according to ISO 1133 at 190 °C. As subscript the load under which the measurement is made is given. Thus, MFR under a load of 2.16 kg is denoted MFR2. Correspondingly, the melt flow rate MFR is determined at 190 °C under a load of 21.6 kg. 21 .

[0063] b) Density

[0064] The density in kg / m 3 is measured according to ISO 1183-1 :2004 Method A on compression moulded specimens prepared according to EN ISO 1872-2 (February 2007).

[0065] c) Volatiles VOC (VDA 277)

[0066] The total emission of a plastomer is determined according to VDA 277:1995 (using gas chromatography and headspace method) by using headspace extraction. The instrument is an Agilent gas chromatograph with a WCOT-capillary column (wax type) of 30 m length and 0.25 mm x 1.0 micron inner diameter (1 pm film thickness). Hydrogen is used as fuel gas and a flame ionization detector is used. The GC is set as follows: 3 min isotherm at 50 °C, heating to 200 °C with 12 K / min, 4 min isotherm at 200 °C, injection temperature: 200 °C, detection temperature: 250 °C, carrier helium, flow - mode split 1 :20 and carrier gas flow rate of 1 ml / min. The emission potential is measured based on the sum of all values provided by the substances emitted after gas chromatography analysis and flame ionization detection (with acetone as calibration standard). The sample (particles, ca. 2 g) is introduced by headspace analysis (20 ml headspace vial) after a treatment of 5 hours at 120 °C prior to the measurement. The unit is micrograms of carbon per gram of sample or ppm.

[0067] d) Average D50 particle size (plastomer particles)

[0068] The particle size distribution and shape evaluation is carried out based on an image analysis method. The particles are transferred onto a vibration table. A high-speed linear camera acquires two-dimensional images of each particle in free-fall mode. The system measures the size of these particles as the diameter of an equivalent circle. The particles are classified into nine classes: 1000 pm, 2000 pm, 2500 pm, 3000 pm, 3500 pm, 4000 pm, 5000 pm, 6000 pm, > 6000 pm.

[0069] The following parameters were determined for each particle: shape factor, elongation, roundness, mesh diameter, convexity and roughness. Depending on the values of these 6 parameters, the particles were classified as: particle, cluster, tailed, multiple, long, dust, angel hair or miscut.

[0070] The measurement of the contaminants on the particles, as well as the particle shape and size, was done using a PA66 consisting of PS25C and PSSD and / or an equivalent instrument setup from OCS GmbH. The PS25C and PSSD can be used independently and can be considered as separate systems.

[0071] e) Flexural modulus

[0072] The flexural modulus was determined on test bars according to ISO 178 in 3-point bending. The test bars were injection moulded according to EN ISO 1873-2 at 23 °C in 80 x 10 x 4 mm 3 The flexural modulus was determined on test bars according to ISO 178 in 3-point bending. The test bars were injection moulded according to EN ISO 1873-2 at 23 °C in 80 x 10 x 4 mm

[0073] e) Vicat temperature

[0074] The Vicat temperature was measured according to ISO 306, method A50. A flat ended needle loaded with 10 N of mass was brought into direct contact with an injection moulded test specimen having dimensions of 80 x 10 x 4 mm 3 as described in EN ISO 1873-2. The specimen and the needle were heated at 50 °C / h. The temperature at which the needle penetrated to a depth of 1 mm was recorded as the Vicat softening temperature.

[0075] f) Temperature

[0076] The temperature was measured with thermocouples on both sides of the gas inlet of the intensified fluid dynamics system.

[0077] Experiment

[0078] Example 1

[0079] A plastomer (C2C8 polyolefin, density 868 kg / m3, MFR (ISO 1133, 190 °C, 2.16 kg) = 0.5 g / 10 min) having an initial VOC content of 1043 ppm in the form of particles (average D50 diameter of 3.5 mm with the method described herein) was used for this first example.

[0080] Reduction of VOC content was evaluated for packed bed column (reference; gas flow rate 10 cm / s), fluidized bed system (superficial gas flow rate 40 cm / s), sparged bed system (superficial gas flow rate 75 cm / s) and dual cone system (superficial gas flow rate 95 cm / s). The table below summarizes the simulation results for the four columns operated with different air flow rates.

[0081] The simulations were based on a dynamic model built in Fortran 90 with MSIMSL numerical library for solving differential equations.

[0082] Table 1. Change in 1-octene concentration (normalized to initial 1-octene concentration) when aerated in beds operated with different air flow rates

[0083]

[0084]

[0085] Example 2

[0086] Example 2 shows the change in normalized concentration of 1-octene inside the polymer particles as a result of aeration with different air superficial velocities (i.e., fluidized system). The simulations demonstrate that the change in hydrocarbon concentration inside the particles is most drastic when aeration occurs under dual cone conditions. In this case, the mass transfer from the particles to the air is maximum, which reduces the surface concentration of octane, with the result that almost no octane is present at the surface of the particles. As a result, this enhances the diffusion of octane from the surface of the particles to the center of the particles, see table below. By reducing the air flow rate, i.e., moving from dual cone to packed bed system, the rate of removal of hydrocarbons from the particles to the air is reduced; however, a significant removal is still detectable when utilizing sparged bed conditions or fluidized bed conditions as compared to packed bed conditions. This results in less removal of hydrocarbons from the particles and thus higher concentrations inside the particles.

[0087] Table 2. Change in normalized 1-octene concentration inside the polymer particles as a result of aeration with different air flow rates

[0088]

Claims

1. A method for reducing the volatile organic compound (VOC) content of a plastic body, as determined according to VDA277, to below 65 ppm, wherein the plastic body has -Equal to or less than 883kg / m 3 The density was determined according to ISO 1183-1:2004 Method A on compression molded specimens prepared according to EN ISO 1872-2; February 2007, and -100.0 g / 10 min or lower MFR2 as determined by ISO 1133 at a load of 2.16 kg and 190 °C; The method includes the following steps: a) Provide a raw material plastic body in granular form, said raw material plastic body having -Equal to or less than 883kg / m 3 density; and MFR2, measured according to ISO 1133 at a load of 2.16 kg and 190 °C, at a rate of -100.0 g / 10 min or lower; and - Volatile organic compound (VOC) content exceeding 150 ppm as determined by VDA277; and - Particles with an average D50 diameter of 2.5 mm to 4.5 mm, as measured by image analysis. b) subjecting the granular raw material plastic body to at least one enhanced hydrodynamic system, wherein the enhanced hydrodynamic system is a fluidized bed system. The apparent gas velocity is higher than the minimum fluidization velocity, and the apparent gas velocity is at least 40 cm / s. The gas is injected via a gas distribution plate, and The temperature is at a minimum of at least 20°C and a maximum of 4°C lower than the Vicat temperature of the granular raw material plastic body measured at 10N according to ISO 306, or 35°C, whichever is lower. The temperature was measured at the gas inlet of the rapid fluidization system. c) Recycle the granular plastic body.

2. The method according to claim 1, wherein the raw material plastide is produced by solution polymerization.

3. The method according to claim 1 or 2, wherein the plastic body is a copolymer of ethylene and 1-octene.

4. The method according to claim 1 or 2, wherein the gas used in the rapid fluidization system is selected from the group consisting of nitrogen, air, and mixtures thereof.

5. The method according to claim 1 or 2, wherein the processing container is an insulated processing container.

6. The method according to claim 1 or 2, wherein the raw material plastic body is preheated in granular form.

7. The method according to claim 1 or 2, wherein entrainment from the enhanced hydrodynamic system is minimized by using at least one gas-solid separator.

8. The method according to claim 1 or 2, wherein the plastic body has a density equal to or less than 870 kg / m³. 3 The density was determined according to ISO 1183-1:2004 Method A on a compression-molded specimen prepared according to EN ISO 1872-2; February 2007.

9. The method according to claim 1 or 2, wherein the raw material plastide is produced by solution polymerization, the method further comprising: (i) subjecting the polymer slurry obtained directly from the solution polymerization reactor to a first separation stage using at least one flash separation to produce a first intermediate polymer; (ii) The first intermediate polymer is passed through an extruder to form a raw material plastic body in the form of granules, the granules of which have an average D50 diameter of 2.5 mm to 4.5 mm as measured by image analysis.

10. The method according to claim 1 or 2, wherein the particles of the raw material plastic body and / or the particles of the plastic body recovered from the at least one enhanced hydrodynamic system are subjected to a purge tower and / or a steam dryer.

11. The method according to any one of claims 1 to 9 is used to homogenize the concentration of volatiles in the obtained particles.

12. The method according to any one of claims 1 to 9 is used to minimize processing time when reducing the volatile organic compound (VOC) content of a raw material plastic body having a VOC content of more than 150 ppm as determined by VDA277 to less than 65 ppm for the resulting plastic body.

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