Apparatus and process for producing polymer particles and use of polymer particles as polymer particle standard

Abstract

An apparatus for producing polymer particles, in particular micropolymer particles, from a polymer substrate (8), comprising a providing component having at least one conducting unit (1) which is configured for conducting the polymer substrate (8) and which at its end comprises at least one nozzle having at least one discharging opening (2) for the polymer substrate (8), a temperature-control unit with which the temperature of the polymer substrate (8) is controllable at least in regions along the conducting unit (1) and a conveying unit with which the polymer substrate (8) is conveyable through the at least one discharging opening (2) in pulsed or continuous fashion, further comprising a receiving component having a unit for receiving individualized polymer particles of the discharged polymer substrate (8) conveyed through the at least one discharging opening (2) in pulsed fashion and / or a separating unit for separating a polymer substrate (8) conveyed continuously through the at least one discharging opening (2) into individual polymer particles during or after discharging, process relating thereto and use of the produced polymer particles as a polymer particle standard.

Description

[0001] Apparatus and method for producing polymer particles and use of polymer particles as polymer particle standard

[0002] The invention relates to a device for producing polymer particles, in particular micropolymer particles, from a polymer substrate and a method for producing polymer particles as well as a use of polymer particles as a polymer particle standard.

[0003] Micropolymer particles are typically formed in the environment through the weathering and fragmentation of larger plastic particles, also known as macroplastic particles. These particles are caused by abrasion from tires and shoe soles, wear and tear on larger plastic parts such as packaging, washing synthetic textiles, and the use of micropolymer particles in cosmetics, as well as by landfills, from which micropolymer particles enter rivers, oceans, coastal areas, and agricultural land.

[0004] Larger plastic particles that enter the environment, also known as macroplastics, are broken down or transformed into smaller so-called micropolymer particles or even so-called nanoplastic particles by UV radiation and mechanical influences, for example.

[0005] Since micropolymer particles are very difficult or impossible to degrade naturally, it can be assumed that the concentration of micropolymer particles will continue to rise. The question of what effects this will have on humans, other organisms, and ecosystems cannot yet be conclusively answered. Answering this question requires considerable research.

[0006] However, it has already been demonstrated that micropolymer particles induce inflammatory reactions in marine organisms, such as mussels, and cause a reduction in growth rate in planktonic crustaceans. Another major problem is the adsorption and absorption of pollutants, such as pesticides and polycyclic aromatic hydrocarbons, by the micropolymer particles, which are then ingested by marine organisms and thus enter the food chain.

[0007] It remains unclear how different micropolymer particle species distribute in the environment and what their residence time is before eventual degradation. Likewise, possible interactions with environmental substances are only partially known and by no means fully understood.

[0008] In this regard, studies are required, which require the provision of micropolymer particles of standardized sizes or according to established standards. Such micropolymer particles should, if possible, also be made up of different polymers in order to simulate similar properties and densities.

[0009] What is needed are standardized polymer particles, particularly micropolymer particles with an average diameter of 1 mm, whose parameters (particle mass, particle shape, particle diameter, and particle volume) can be specified and which can be produced reproducibly. A defined scattering of the specified parameters, for example with regard to particle size, may also be necessary in order to achieve a targeted distribution of the micropolymer particles to be produced, for example, within a specific range of mass or diameter. This can be done by better simulating the occurrence of micropolymer particles in nature.

[0010] Such standardized micropolymer particles are required for microplastic analysis, in which, for example, the polymer type and polymer mass of potentially contained microplastics in an environmental sample is examined, for the calibration of analytical instruments and as test material or markers (tracers) to elucidate the entry routes of microplastics or their behavior, for example, in the environment and in water treatment processes.

[0011] According to the National Oceanic and Atmospheric Administration's definition, microplastics are characterized by particles smaller than 5 mm in size, with particles between 1 nm and a maximum of 1000 nm being referred to as nanoplastics. Of particular interest are particles with a particle size in the micrometer range.

[0012] Uniform standard micropolymer particles are particularly required for the validation of micropolymer particle analysis, in which standard micropolymer particles can be specifically added to a sample as an internal standard, allowing a correction of the analysis result after sample preparation and analysis. Calibration and validation of the preparation and / or analysis processes can also be carried out using the standard micropolymer particles proposed here. Thus, for example, in a sample preparation procedure and / or analysis procedure, sources of error can be specifically identified and optimized by determining the recovery rate of the previously added standard micropolymer particles.Since the use of different analytical methods produces very different results, for example, with differential scanning calorimetry (DSC) regarding particle mass and polymer type, and with Raman microscopy regarding particle number and polymer type, it is not possible to convert the results from environmental samples or distributed standard materials with sufficient accuracy and at a reasonable cost. This means that uniform standards are required or methods with mathematically describable property gradients that allow the results of different methods to be compared, validated, and harmonized.

[0013] According to the state of the art, polymer dispersions with colloidal polymer particles can be produced by polymerizing a polymer species in a given emulsion or suspension. This process, which produces a dispersion of polymer particles in a mostly aqueous phase with polymer particle diameters between a few tens of nanometers and a few micrometers, is only feasible for certain polymer species and is limited in the achievable particle diameter and particle size distribution.

[0014] A device for producing micropolymer particles is known from KR 102357703 B1. The problem to be solved is to provide a device for producing microplastics for use in testing procedures.

[0015] To solve this problem, a device is provided which has several radiation units and pulverizing units in a container, wherein weather influences and mechanical influences on a plastic are simulated in the container in order to achieve accelerated aging of the plastic and to produce the micropolymer particles.

[0016] It is also known to produce artificial micropolymer particles by abrasion or comminution of larger particles, for example, by cryogenically grinding larger plastic components in a mill and subsequently fractionating them into the desired size fractions by sieving. This process generally results in micropolymer particles with a narrow distribution, which requires additional fractionation, for example, by sieving, for narrowly distributed standards. Cryogenic technology also causes fracture behavior that does not correspond to the typical abrasion and fracture mechanisms under mechanical stress in the environment. This is because the material is subjected to stress below its usual service temperature, usually even below its glass transition temperature, and is thus crushed in a more brittle state than is the case under typical ambient conditions.

[0017] In the field of plastics processing, plastic freeforming is also known as an additive manufacturing process for the production of thermoplastic components, in which three-dimensional components can be produced from qualified standard plastic granules. In plastic freeforming, standard plastic granules are melted and dispensed in droplet form through a nozzle with a closure. These droplets are used to build up the component to be manufactured layer by layer.

[0018] DE 20 2020 101 503 U1 discloses a print head with at least one feed for a meltable filament and a body produced using an additive manufacturing process. The problem to be solved is to create a way to create both fine contours and coarse contours with large layer thicknesses using the same, essentially unchanged nozzle.

[0019] To achieve this, a print head is provided which has a mask arranged behind the nozzle in the flow direction and has at least one passage opening for at least one filament heated above its melting or softening temperature, wherein the mask is arranged exchangeably and / or movably on a holder of the print head and / or at least one passage opening of the mask has an adjustable and / or variable cross-sectional shape and / or cross-sectional area.

[0020] According to the known state of the art, there is no sufficiently precise method for the reproducible production of micropolymer particles with specified parameters such as quantity, size or diameter, shape or mass of the micropolymer particles, whereby the produced micropolymer particles should have a size or diameter in the range between 0.02 mm and 2.0 mm. In addition, the time required for the individual process steps for the production of micropolymer particles, for example through abrasion or comminution, is very high. Furthermore, losses occur during sieving and liquid nitrogen is required for grinding, which leads to high production costs. In addition, the material, which becomes embrittled due to cooling, creates surfaces with different properties than those produced in natural processes.

[0021] Thus, there is a need for a way to produce polymer particles, in particular micropolymer particles, from a polymer substrate.

[0022] The object of the invention is therefore to propose a device for producing polymer particles, in particular micropolymer particles, with which polymer particles with defined parameters such as particle mass, particle shape, particle diameter and / or particle volume can be produced continuously and in a predetermined number from different polymers, wherein the size or diameter of the polymer particles is in a range of less than 5.0 mm. The object of the invention is further to propose a method for producing polymer particles, in particular micropolymer particles, in a predetermined number with defined parameters such as particle mass, particle shape, particle diameter and / or particle volume. The production of the polymer particles should be both cost-effective and time-effective.

[0023] According to the invention, polymer particles with a diameter in a range between 0.02 mm and 2.0 mm, in particular between 0.05 mm and 1.0 mm, and more particularly between 0.1 mm and 0.5 mm, are to be produced. This should also make it possible to produce polymer particles with predetermined range limits of their parameters, so that, for example, micropolymer particles of different sizes can be produced with a uniformly distributed number within a predetermined range.

[0024] This object is achieved by a device having the features of claim 1 and a method having the features of claim 23. Further developments are specified in the dependent claims. Uses of the polymer particles as a polymer particle standard are specified in claim 36.

[0025] A device is provided for producing polymer particles, in particular micropolymer particles, from a polymer substrate. The device has two essential components: a supply component and a receiving component. The supply component has at least one conduit unit designed to convey a polymer substrate, which at its end has at least one nozzle with at least one discharge opening for the polymer substrate. A further component of the supply component is a temperature control unit, with which the polymer substrate can be temperature-controlled at least in certain regions along the conduit unit. The temperature control unit is provided to temperature-control the polymer substrate present in the conduit unit along the conduit unit, i.e., to cool and / or heat it.Temperature control of the polymer substrate may be necessary, on the one hand, to ensure the strength of the polymer substrate and, on the other hand, to influence the flowability of the polymer substrate. Furthermore, the supply component comprises a conveying unit with which the polymer substrate can be conveyed in a pulsed or continuous manner through the conduit unit and through the at least one discharge opening. Continuous conveying may be provided to convey a molten form of the polymer substrate, provided as a result of the temperature control, as a polymer substrate jet through the at least one discharge opening of the at least one nozzle.

[0026] The temperature control along the line unit depends in particular on the type of conveyance of the polymer substrate through the line unit. Therefore, it can be provided that the temperature control is controllable depending on the conveying speed of the polymer substrate.

[0027] For the sake of simplicity, the feature of at least one discharge opening is hereinafter referred to simply as discharge opening.

[0028] The receiving component is provided to receive polymer substrate dispensed at the discharge opening and, if necessary, to separate it, i.e., to divide it. The receiving component downstream of the supply component comprises a unit for receiving individualized polymer particles of the dispensed polymer substrate that are conveyed in a pulsed manner through the discharge opening. In the simplest case, the receiving unit is a container in which the individualized polymer particles produced are collected. Alternatively or additionally, the receiving component has a separating unit for separating, in particular shearing off, the polymer substrate that is continuously conveyed through the discharge opening in the form of a polymer substrate jet. The separating unit is provided to separate, i.e., shear off and separate, the polymer substrate emerging from the discharge opening in the form of a polymer substrate jet into individual polymer particles during or after dispensing.A continuously dispensed strand of the polymer substrate can be separated into individual polymer particles, particularly micropolymer particles, using the separation unit. Various means can be used to separate the polymer substrate stream conveyed through the discharge opening, enabling targeted shearing of the polymer substrate stream. Corresponding means and devices of the separation unit are described below. The separation unit is preferably associated with the container for receiving the individualized polymer particles produced, so that the individualized polymer particles can pass directly from the separation unit into the container.

[0029] The container of the receiving component can contain a liquid or be purged with a gas. It has been shown that the particle properties can be influenced by the type of fluid present in the container and the fluid temperature. Cooling the liquid contained in the container is advantageous, as this achieves rapid solidification of the resulting polymer particles upon immersion.

[0030] The supply component may comprise means for storing the polymer substrate in the form of a storage container. Furthermore, means for transporting the polymer substrate, which is usually present in solid form, may be provided to convey the stored polymer substrate to the line unit.

[0031] According to one embodiment of the device according to the invention, the conduit unit can be designed in the form of a tube, wherein the tube end, whose mouth forms the at least one discharge opening, is designed in the form of a nozzle. Accordingly, the conduit unit can be designed as a tapered tube with a nozzle opening side, wherein the at least one discharge opening is located on the nozzle opening side.

[0032] According to one embodiment of the device according to the invention, the conveying unit can comprise an extruder with an extruder screw arranged in the line unit. Rotation of the extruder screw converts a solid, supplied polymer substrate into a molten mass, which can be extruded through the at least one discharge opening. During extrusion, additional heating or cooling may be required. For this purpose, the temperature control unit is provided to temperature-control the polymer substrate present in the line unit along the line unit or along the extrusion path. Further embodiments of the temperature control unit are specified in the further description.

[0033] According to a further embodiment of the conveyor unit, a filament feed can be provided, wherein a solid polymer substrate filament is used as the polymer substrate. This polymer substrate filament, which can be provided as a section or as a continuous filament, is introduced into the conveyor unit and clamped between two counter-rotating, toothed rollers. By driving one or both rollers, the polymer substrate filament can be moved or conveyed along a defined path or feed in a conveying direction or a polymer feed direction or against this conveying direction.

[0034] The filament feed can interact with the solid polymer substrate filament such that the polymer substrate filament forms a pressure piston within the conduit unit, which can exert a compressive force in the direction of the discharge opening. The compressive force is utilized to convey polymer substrate provided in molten form in the conduit unit through the discharge opening. This design of the conveying unit relies in particular on interaction with the temperature control unit. Temperature control zones are provided along the conduit unit in the conveying direction of the polymer substrate filament. A heating zone for heating the polymer substrate filament extends toward the discharge opening to enable the polymer substrate to pass through in a molten form, i.e., in a flowable molten form.The filament feed enables a back-and-forth movement of the polymer substrate filament, enabling pulsed conveying of the polymer substrate and, consequently, pulsed discharge of the polymer substrate from the discharge opening. Individual polymer particles can be produced as soon as they pass through the discharge opening as a result of a pulse. A stepper motor or a piezo element, for example, can be used for pulsed conveying. Accordingly, the conveying unit can have a piezo element. The piezo element can preferably generate vertical mechanical oscillations. The vertical mechanical oscillations cause defined volumes of the molten polymer substrate to be ejected from the discharge opening of the nozzle. As a result of a vibration pulse, a droplet breaks off from the molten polymer substrate, forming a single polymer particle.The piezo element can be used to generate vibrations with a frequency in the range of 10 Hz to 400 kHz and an amplitude of 1 mm. Furthermore, the nozzle at the end of the line unit can be set into vibration to support the production of individual polymer particles.

[0035] The vibrational excitation enables droplets of the molten polymer substrate to produce polymer particles.

[0036] The frequency of the completed oscillations allows for inference about the number of polymer particles produced, so the number of oscillations performed can be used to verify the number of polymer particles produced. Likewise, a predetermined number of polymer particles to be produced can be specified by setting a specific number of oscillations to be performed.

[0037] For pulsed conveying, the conveying unit is alternatively or additionally configured to execute a forward-backward or reciprocating movement of the polymer substrate filament by means of the filament feed within the conveying unit, whereby a backward movement of the polymer substrate filament away from the discharge opening corresponds only to a portion of the path of the forward movement of the polymer substrate filament. The forward-backward or reciprocating movement of the polymer substrate filament can be controlled by a control component.

[0038] Both the pulsed conveying and the continuous conveying of the polymer substrate through the discharge opening of the line unit are realized by the conveying unit. This design requires interaction with the separation unit, which divides a continuously emerging polymer substrate stream into individual polymer particles.

[0039] In the alternative pulsed conveying, which includes not only a movement of the polymer substrate in the direction of the discharge opening (polymer feed direction) but also a movement of the polymer substrate in the opposite direction away from the discharge opening generated by the conveying unit, it is possible to dispense or produce individual polymer particles of the polymer substrate.

[0040] To ensure economical operation of the device, it is necessary that the largest possible number of polymer particles can be produced per unit of time. To this end, the units of the supply component and the receiving component are coordinated with each other, with the control component configured to control the units of the receiving component depending on the units of the supply component.

[0041] The components of the device for producing polymer particles from a polymer substrate are specifically adapted to the properties of the polymer substrates to be processed, as well as the parameters specified for the polymer particles (particle mass, particle shape, particle length, particle width, particle height, particle diameter, and particle volume), so that polymer particles can be produced from different polymers for standard tests. For the production of micropolymer particles, thermoplastic polymers such as PE (polyethylene), PP (polypropylene), PVC (polyvinyl chloride), PS (polystyrene), PCL (polycaprolactone), PLA (polylactide), ABS (acrylonitrile-butadiene-styrene copolymer), ASA (acrylonitrile-styrene-acrylate copolymer), TPU (thermoplastic polyurethane), and PET (polyethylene terephthalate) can be used as polymer substrates.The polymer substrate can also be present and fed in as bulk material, unless a polymer substrate filament with polymer feed is used according to an embodiment of the device according to the invention.

[0042] From now on, this description will refer only to the conducting unit of the delivery component. It will be clear to a person skilled in the art that the conducting unit is integrated into the delivery component and cannot operate independently of other means of the delivery component. This description generally refers to a liquefied, molten polymer substrate, which is also intended to encompass polymer states such as viscous, leather-like, or liquid.

[0043] According to the invention, the polymer substrate conveyed through the conduit unit is ultimately in the form of microvolume polymer particles, the micropolymer particles to be produced. The polymer substrate conveyed through the conduit unit and discharged through the discharge opening of the conduit unit can be divided or separated by handling of the conduit unit itself during pulsed conveying or by means of the receiving component, such as a separation unit.

[0044] It is provided that the device has a control component with which the receiving component can be controlled depending on the provision component.

[0045] The line unit of the supply component can be arranged to be movable. According to one embodiment, it can be provided that the line unit is movable horizontally and vertically along its longitudinal axis by means of a drive unit. The provided control component enables a coordinated movement of the line unit and the receiving component relative to one another. Thus, it is possible, for example, to displace or move the line unit horizontally over a receiving component designed as a build bed in an X-direction and in a Y-direction, while the receiving component is not moved, in order to deposit the pulsed-conveyed polymer particles, for example one after the other, in different areas of the surface of the receiving component. Alternatively, for such a deposition, the receiving component is displaced or moved horizontally in an X-direction and in a Y-direction, while the line unit is not moved.

[0046] Furthermore, the control component also influences a distance between the discharge opening arranged on a nozzle opening side of the line unit and the surface of the receiving component, for example to ensure that the pulsed conveyed polymer particles can be safely deposited on the surface of the receiving component at a short distance from the surface.

[0047] The control component can further be configured to control the receiving component and / or the separation unit depending on a quantity per unit of time of the polymer substrate conveyed through the discharge opening.

[0048] Depending on the amount of polymer substrate conveyed in a pulsed manner per unit of time, the speed of the line unit is adjusted as it moves over the surface of the stationary receiving component. The line unit moves faster over the surface of the receiving component when a larger amount of polymer substrate is conveyed in a pulsed manner via the discharge opening, and vice versa. This ensures that the pulsed polymer particles are reliably deposited or collected on the surface of the receiving component or in a corresponding receiving container, while ensuring a distance between the deposited polymer particles. Alternatively, with a stationary line unit, the speed of the receiving component moving beneath the line unit can be adjusted depending on the amount of polymer substrate conveyed in a pulsed manner per unit of time.

[0049] Depending on the amount of polymer substrate jet continuously conveyed per unit of time, the speed at which the separation unit produces individual polymer particles through a separation process for separating the continuously conveyed polymer substrate is adjusted. Thus, with a larger amount of polymer substrate jet conveyed through the discharge opening per unit of time, the number of separation processes of the separation unit per unit of time is increased in order to keep the parameters specified for the production of the polymer particles, such as particle mass, particle shape, particle diameter, and particle volume, constant.

[0050] The discharge opening has a diameter in the range of 0.02 mm to 0.2 mm. The size and shape of the discharge opening can be created using a laser or an EDM process, for example.

[0051] The temperature control unit can have a cooling means and a heating means, wherein the cooling means is assigned to a cooling zone and the heating means is assigned to a heating zone. The cooling zone and the heating zone are arranged along the line unit. Electrical means, such as Peltier elements, can be used for cooling and / or heating. An electric heating rod or an electric heating coil can also be provided as the electric heating means. The use of microwave radiation for heating is also conceivable. A heat-conducting temperature control fluid is preferably used as the heating and / or cooling means.

[0052] The cooling means or the heating means can be arranged outside or inside the line unit.

[0053] By means of such coolants or heating means, the polymer substrate conveyed through the line unit is cooled or heated independently in different regions of the line unit. Thus, the polymer substrate can be heated by the heating means in the region of a heating zone such that it transforms into a flowable form, while at the same time the polymer substrate in the line unit in the region of a cooling zone is cooled by the coolant and is in a solid form. In solid form, the polymer substrate can be moved in the line unit in the longitudinal direction of the line unit towards the discharge opening in a controlled manner by means of the conveying unit. The solid polymer substrate acts like a piston on the liquefied polymer substrate in the region of the discharge opening, whereby the flowable polymer substrate is pressed through the discharge opening of the line unit.

[0054] According to an advantageous embodiment, the temperature control unit has fluid-carrying channels, wherein circumferential first channels for a first temperature control fluid are arranged in a wall of the line unit, wherein the first channels are assigned to the heating zone. Furthermore, circumferential second channels for a second temperature control fluid are formed in the wall of the line unit, wherein the second channels are assigned to the cooling zone. A temperature control fluid can flow through the first channels, so that the polymer substrate located in the line unit can be heated in the region of these first channels and thereby liquefied. The second channels arranged in the wall of the line unit, which are spaced from the discharge opening of the line unit, can be flowed through by a second temperature control fluid, so that the polymer substrate in the line unit can be cooled. Melting of the polymer substrate in the region of the second channels can thus be prevented.The heating zone is preferably located at the discharge opening or in a region of the discharge opening of the line unit, with the cooling zone being located at a distance from the discharge opening of the line unit. The heating zone is advantageously formed in the region of the discharge opening to achieve sufficiently good flowability of the polymer substrate, allowing it to pass through the discharge opening with minimal force.

[0055] By means of such zone-divided temperature control, in combination with a targeted, time-limited feed of the polymer substrate in the form of a filament, it is possible to discharge a specific portion of the polymer liquefied in the area of ​​the discharge opening of the line unit in a pulsed manner through the discharge opening of the line unit.

[0056] Alternatively, it is possible to continuously discharge the polymer substrate present in molten form in the region of the first channels in the line unit from the discharge opening of the line unit in the form of a polymer substrate jet.

[0057] According to an advantageous embodiment of the device according to the invention, the line unit has a plurality of discharge openings on the nozzle opening side of the at least one nozzle, wherein the plurality of discharge openings can be arranged in a row or in the form of a matrix with a plurality of rows and a plurality of columns.

[0058] The presence of multiple discharge openings enables the simultaneous production of a larger number of polymer particles in a single operation or process step. When using a nozzle with multiple discharge openings, pulsed discharge or droplet formation of the molten polymer substrate is preferred, since shearing can impair the formation of individual polymer particles. The simultaneous discharge of multiple polymer particles can be combined with the direct deposition of the produced polymer particles onto a deposition surface of the receiving component, whereby the produced polymer particles can cool separately from one another on the deposition surface.

[0059] The receiving component can comprise a unit for receiving individualized polymer particles conveyed in a pulsed manner through the at least one discharge opening, a plate arranged opposite the at least one discharge opening for depositing the generated polymer particles. The plate can be made of a glass material. By using a nozzle with multiple discharge openings, several polymer particles can be deposited simultaneously in a row or matrix onto the surface of the plate.

[0060] The surface of the plate or the plate itself can preferably be temperature-controlled in a range between 50°C and 60°C. The pulsed polymer particles are deposited separately onto the plate. To enable this, the at least one nozzle with the at least one discharge opening and the plate are movable relative to one another. The temperature control of the plate advantageously prevents the produced polymer particles from cooling too quickly. Furthermore, by switching off the temperature control, the polymer particles produced and deposited on the plate can cool simultaneously. Due to the different thermal expansion coefficients of the plate material and the produced and deposited polymer particles, simplified detachment of the polymer particles from the plate surface is promoted when the temperature control is switched off.

[0061] The separate deposition of produced polymer particles advantageously enables control of the number of polymer particles to be produced.

[0062] According to one embodiment, the plate can be elastic and / or have a non-stick coating or be made of a non-stick material. The non-stick coating can be a coating made of polytetrafluoroethylene (PTFE), or the plate can be made of PTFE. An elastically designed plate has the advantage that the deposited polymer particles produced can be more easily removed due to elastic deformation.

[0063] According to a further embodiment of the receiving component, the receiving component can have a rotatable roller arranged opposite the at least one discharge opening as a unit for receiving individualized polymer particles conveyed in a pulsed manner through the at least one discharge opening for depositing generated polymer particles, wherein the rotatable roller is assigned a scraper with which polymer particles deposited on the rotatable roller can be scraped off. Produced polymer particles can be deposited separately on the rotatable roller, wherein the rotatable roller rotates by a predetermined angular step. To release generated, deposited polymer particles, the scraper is provided, which scrapes over the roller surface as a result of the roller rotation. A collecting container is assigned to the scraper, in which the detached polymer particles are collected or received.By using a nozzle with multiple discharge openings, several polymer particles can be deposited in a row on the roller surface at the same time.

[0064] The rotatable roller can preferably be temperature-controlled in a range between 50 °C and 60 °C. Furthermore, the surface of the rotatable roller can have a non-stick coating with PTFE or another non-stick coating to facilitate the removal of the polymer particles deposited on the surface of the rotatable roller.

[0065] The discharge openings have the same diameter, which can range from 0.02 mm to 0.2 mm. This allows a series of identical or monodisperse micropolymer particles to be produced in a single operation using a single line unit, so that the polymer particles produced have the same parameters, particularly with regard to their size and mass. The diameter of polymer particles produced in this way is usually larger than the diameter of the discharge opening due to the possible or expected so-called strand expansion, which leads to an increase in the diameter of the polymer substrate leaving the narrow discharge opening due to elasticity and entropy.With a diameter of the discharge opening in the range between 0.02 mm and 0.2 mm, polymer particles with a diameter in a range between 0.02 mm and 2.0 mm, in particular in a range between 0.05 mm and 1.0 mm, further in particular in a range between 0.1 mm and 0.5 mm can be produced, for example, depending on the polymer substrate used and the exit speed of the polymer substrate at the discharge opening.

[0066] Alternatively, the multiple discharge openings of the conduit unit can have different diameters. Thus, a series of different polymer particles can be produced using a conduit unit in a single operation, with the resulting polymer particles having different parameters, particularly with regard to their size and mass.

[0067] The discharge openings of the conduit unit can have a round, elliptical, rectangular, triangular, or star-shaped cross-section. Corners of these cross-sections can be rounded with a radius. By varying the geometry of the discharge opening of the conduit unit, the shape of the micropolymer particles to be produced can be influenced in particular.

[0068] The line unit can have a nozzle needle by means of which the discharge opening can be closed. Such a nozzle needle is moved away from the area of ​​the discharge opening of the line unit in order to free the discharge opening and to allow, for example, liquefied polymer substrate in the area of ​​the discharge opening of the line unit to escape from the discharge opening. Once a predetermined amount of the liquefied polymer substrate has escaped from the discharge opening, the nozzle needle seals the discharge opening again. This prevents further dripping of the liquefied polymer substrate. By controlling the movement of the nozzle needle, a portioned, pulsed release of individual portions of the liquefied polymer substrate can be achieved. By using the nozzle needle, it is possible to determine the number of polymer particles produced based on the movements performed with the nozzle needle.In this way, the number of polymer particles to be produced can be specified or checked.

[0069] According to one embodiment of the device according to the invention, the separation unit can comprise a single doctor blade, which can be moved back and forth across the at least one discharge opening at a predetermined speed to shear off the polymer substrate emerging from the at least one discharge opening. The frequency of the back-and-forth movement of the single doctor blade is controllable depending on the conveying speed of the polymer substrate stream continuously emerging from the discharge opening.

[0070] In a further advantageous embodiment, the separation unit comprises a doctor blade shaft having a plurality of doctor blades, wherein the doctor blade shaft is rotatably arranged such that the doctor blades sweep over the at least one discharge opening when the doctor blade shaft rotates. Such a multiple doctor blade is arranged in front of the nozzle opening side of a line unit of the supply component such that the doctor blades are guided one after the other past the discharge opening of the line unit located on the nozzle opening side by a rotary movement of the doctor blade shaft. A multiple doctor blade can, for example, comprise two, four or more doctor blades rotating with the shaft. The polymer particles scraped off and collected by the doctor blades from the discharge opening of the line unit cool down, harden, and can be scraped off by the rotating doctor blades, for example by means of a scraper, in an area spaced from the line unit and collected in a collecting container.The receiving container or collection container is assigned to the doctor blade shaft in such a way that the doctored polymer particles are collected.

[0071] The rotation of the doctor blade shaft is controllable depending on the conveying speed of the polymer substrate jet continuously emerging from the discharge opening. Alternatively, the rotating doctor blade can be moved axially. Alternatively, the nozzle can be moved horizontally in the axial direction of the rotating doctor blade. The doctor blade can be cooled to facilitate curing and detachment of the generated polymer particles.

[0072] Both when using individual doctor blades and when using multiple doctor blades on a doctor blade shaft, the distance of the corresponding doctor blade to the discharge opening can be regulated, which allows any thermal length changes that occur to be compensated.

[0073] Alternatively or additionally, the separation unit can have at least one gas nozzle assigned to the at least one discharge opening, wherein the gas nozzle can be used to deliver a directed gas jet onto the polymer substrate exiting the at least one discharge opening in order to shear off individual polymer particles from an exiting polymer substrate jet. Preferably, the gas jet is directed transversely to the exiting polymer substrate jet. The frequency of the gas jets is controllable as a function of the conveying speed of the polymer substrate jet. Controlling the conveying speed of the polymer substrate jet and the gas discharge frequency enables the production of essentially identical polymer particles, which can be used to produce polymer particle standards.Furthermore, the frequency of the gas pulses allows conclusions to be drawn about the number of polymer particles produced, so that the number of gas pulses carried out can be used to check the number of polymer particles produced.

[0074] The control component can be configured to control a reciprocating movement of the individual doctor blade, a rotation of the doctor blade shaft, and a gas discharge frequency of the gas nozzle as a function of the conveying speed of the polymer substrate through the at least one discharge opening. By influencing the pulse frequency and / or the mass flow of the polymer substrate jet, at least the size and mass parameters of the polymer particles to be produced can be influenced. The micropolymer particles produced in this way are collected, for example, in a collecting container. Other possibilities for collecting the polymer particles produced in this way include an electrostatically chargeable surface, a liquid, an adhesive surface, or a vacuum filter system such as a vacuum cleaner.

[0075] According to a further embodiment of the device according to the invention, the receiving component can have a surface with recesses into which pulsed polymer substrate is delivered. Such recesses are provided to influence at least part of the shape of the polymer particles, since the volumes of polymer substrate delivered in pulses by the conduit unit are molded into the recesses. The polymer particles cured in the recesses are transferred to a collection container. The surface of the recesses can have a non-stick coating, for example, a polytetrafluoroethylene (PTFE) coating, to facilitate detachment.

[0076] The shaping recesses can be arranged on a roller. The roller can be arranged with the recesses of a discharge opening in such a way that produced polymer particles can be deposited into the recesses in molten form. After the recesses along a row have been filled, the roller rotates further through a specified angle before further dispensing of molten polymer substrate into the recesses of the roller occurs. The polymer particles formed in the recesses of the roller are demolded and fall, for example, into a collection container arranged beneath the roller or are scraped off the surface of the roller with a doctor blade, for example, and thus reach the collection container.

[0077] An electrostatically charged surface can also be used to collect the polymer particles after they have been stripped off by the individual doctor blade. The use of such an electrostatically charged surface is also conceivable in other embodiments of the invention for collecting the polymer particles, which can then be stripped off and portioned, for example, when a predetermined number of polymer particles is reached.

[0078] According to a further embodiment, the receiving component can have a device for the thermal treatment of produced polymer particles. Such a device can have a radiant heater arranged along a drop path for produced polymer particles in order to apply heat radiation to the produced polymer particles. Such a thermal treatment can be provided in order to influence the shaping and curing of the produced polymer particles before they reach a collection container. According to one embodiment, the device for thermal treatment can have a microwave radiation source with which microwave radiation can be directed onto produced polymer particles. The thermal treatment can further comprise temperature control in the form of cooling, wherein such a device provides means for cooling, such as a cooling gas stream.

[0079] The advantages of the device for producing polymer particles lie in particular in the possibility of:

[0080] - high-frequency production of polymer particles with defined parameters (volume, mass), i.e. particles of a size class,

[0081] - cost-effective production of a large number of polymer particles,

[0082] - Determination of the number of polymer particles to be produced and

[0083] - easy adaptation of the shape of the polymer particles to be produced.

[0084] The device according to the invention for producing polymer particles can process all currently common thermoplastics. Furthermore, the device is also suitable for use with biodegradable materials, such as polymer substrates made of PLA (polylactide) and PCL (polycaprolactone).

[0085] The device or machine tool for producing polymer particles from a polymer substrate exhibits high static, dynamic, and thermal rigidity to ensure compliance with relevant parameters such as particle mass, particle shape, particle diameter, and particle volume during the production of the polymer particles. The device is designed such that the thermal plane of symmetry lies at the nozzle end, i.e., at the discharge opening.

[0086] The device according to the invention is designed for the production of monodisperse polymer particles in which the size and shape of the particles are adjustable and controllable. Furthermore, a thermal post-treatment of the particles that influences the particle shape can be provided.

[0087] The invention further comprises a method for producing polymer particles. The method can be carried out using the device according to the invention. Accordingly, the device can be used for producing polymer particles for a polymer particle standard.

[0088] A method is proposed for producing polymer particles, in particular micropolymer particles, with a predetermined particle shape and a predetermined particle size, wherein the polymer particles are provided by dropletizing a polymer substrate by means of a nozzle or by shearing a polymer jet of the polymer substrate conveyed through a discharge opening of the nozzle. The method comprises the following steps: In a first step, a polymer substrate is provided in a molten form. In this process, an initially solid polymer substrate is converted into a flowable, molten form by temperature control and / or the influence of a compressive force. In a second step of the method, the molten polymer substrate is dropletized to produce individual polymer particles, wherein the particle shape and particle size are controlled by controlling the drop volume and the drop discharge speed.The droplet formation process can be supported, for example, by pulsed conveying of the molten polymer substrate, whereby pulsed conveying through the discharge opening causes the separation of individual droplets. The droplet volume and droplet discharge velocity can be influenced by adjusting the conveying speed, the pulse frequency, and the size of the discharge opening's opening cross-section.

[0089] Alternatively, as a second step, a continuously conveyed polymer jet of the molten polymer substrate can be sheared to produce individual polymer particles. The particle shape and size are controlled by controlling the shear width and shear rate of the polymer jet as a function of the conveying speed of the polymer jet of the molten polymer substrate. Individual polymer particles are produced as a result of the repeated shearing of the continuously conveyed polymer jet. The shear width corresponds to the length of a polymer particle sheared off by the continuously conveyed polymer jet.

[0090] The third step involves collecting the separated polymer particles into a container. This step can be combined with further process steps for post-treating the produced polymer particles. During or after the production of the polymer particles, the number of polymer particles provided is checked. Checking the number of polymer particles is intended to obtain a polymer particle standard with a specific number of polymer particles.

[0091] The number of polymer particles provided can be checked optically or with an optical counting device. This may require additional equipment, which can be designed as a component of the device according to the invention. Laser diffraction particle size analysis can also be used to check the number and size. A simpler way to check the number of polymer particles obtained is to record the frequencies of component movements of the device according to the invention, which is used to separate the molten polymer substrate. Thus, the number of polymer particles can be checked alternatively or additionally based on the number of separations of the provided molten polymer substrate carried out by dripping or shearing.Specifically, the number of polymer particles produced can be derived from the pulses executed during pulsed conveying of the polymer substrate.

[0092] The dropletization of the flowable polymer substrate into individual polymer particles can be achieved by subjecting the flowable polymer substrate to vertical mechanical vibrations in a range from 10 Hz to 400 Hz. The vibrations can be generated using a conveyor device with a filament feed for a polymer substrate filament. A polymer substrate filament is used, which is solid in the region of the filament feed and is present in molten form at a discharge opening of the nozzle. To generate the vibrations, the polymer substrate filament is moved back and forth using a roller feed. Alternatively, the vibrations can be generated using a piezo element. The vertical mechanical vibrations cause defined volumes of the molten polymer substrate to be ejected from the discharge opening of the nozzle. As a result of a vibration pulse, a droplet breaks off, forming a polymer particle.Thus, the number of polymer particles produced can be verified based on the number of completed oscillations according to a specified specification. Based on the number of oscillations to be performed, the number of polymer particles to be produced for the polymer particle standard can be specified. It can be assumed that one completed oscillation corresponds to one produced polymer particle.

[0093] The number of droplets ejected per oscillation can be influenced by using nozzles with more than one discharge opening. Thus, multiple droplets, and thus multiple polymer particles, can be produced per oscillation. Advantageously, a specific number of polymer particles are produced simultaneously under identical process conditions so that the resulting polymer particles have essentially the same shape and size. The particle size and shape are controlled by controlling the droplet volume and droplet discharge speed. The droplet volume can be adjusted by the opening cross-section of the discharge opening and the oscillation stroke of the vertical mechanical oscillations of the nozzle. The droplet discharge speed, which influences the particle shape, can be influenced by the oscillation speed.

[0094] It is important that consistent process conditions apply to provide essentially identical polymer particles of a polymer particle standard.

[0095] To separate the polymer substrate, alternatively, shearing of a polymer jet of the molten polymer substrate can be provided. The polymer jet is generated as a result of the continuous conveyance of the molten polymer substrate through the discharge opening of the nozzle. To shear off individual particles, a doctor blade can be guided over the discharge opening of the nozzle. The doctor blade is preferably moved over the discharge opening at a speed dependent on the conveying speed of the polymer jet, whereby the particle shape and particle size can be influenced depending on the movement speed of the doctor blade and the conveying speed of the polymer jet. The number of polymer particles can be specified and checked based on the number of doctor blade movements performed in order to obtain a specific particle number of polymer particles for the polymer particle standard.

[0096] Alternatively, the polymer jet of the molten polymer substrate can be sheared off with a pulsed gas jet from a gas nozzle. Such a gas nozzle can be arranged at the nozzle's discharge opening to direct a gas jet as perpendicularly as possible onto the polymer jet. The targeted gas jet interrupts the polymer jet, forming individual polymer particles. The number of polymer particles can be checked or adjusted based on the number of gas jets to obtain a specific number of polymer particles for the polymer particle standard.

[0097] The molten and thus flowable polymer substrate can be provided by heating the polymer substrate alone or in conjunction with the application of a compressive force. Therefore, it can be provided that the polymer substrate from which the polymer particles of the polymer particle standard are provided is heated and additionally subjected to a compressive force, whereby the increased pressure promotes melt-liquefaction of the polymer substrate. Furthermore, it can be provided that, to provide the molten state of the polymer substrate, the polymer substrate is subjected exclusively to a compressive force, without the need for temperature control. For example, it can be provided that the polymer substrate is extruded in order to convert the polymer substrate into the molten form.

[0098] The polymer particles of the polymer particle standard can be made from a polymer substrate selected from a group consisting of polyethylene (PE), polypropylene (PP), polyvinyl chloride (PVC), polystyrene (PS), polycaprolactone (PCL), polylactide (PLA), acrylonitrile-butadiene-styrene copolymer (ABS), acrylonitrile-styrene-acrylate copolymer (ASA), and thermoplastic polyurethane (TPU). The polymer substrate used as the basis for the production of the polymer particles of the polymer particle standard can also consist of a mixture of the listed polymers. Polymer substrates with different compositions of specific polymer proportions can be provided for the production of the polymer particle standard.

[0099] The polymer particle standards are produced with polymer particles that have essentially the same diameter. The diameter of the produced polymer particles can be adjusted between 0.02 mm and 2.0 mm. For the purposes of the invention, micropolymer particles are understood to be polymer particles with a diameter of less than 1 mm.

[0100] During the production of the polymer particle standards, it can be provided that the polymer particles produced are immediately tempered, for example, cooled, after dropletization or shearing. Preferably, the polymer particles produced are tempered below the glass transition temperature of the polymer substrate used, or of the polymer species or polymer species composition used as the polymer substrate. It can be provided that the resulting polymer particles are tempered at a temperature below -18 °C, preferably at a temperature below -50 °C, in order to fix the resulting shape as a result of the solidification of the polymer particles produced.

[0101] Furthermore, it can be provided that the polymer particles produced are subjected to a heat treatment immediately after dropletization or shearing. This can be provided to influence the shape of the formed polymer particles.

[0102] Furthermore, it can be provided that the resulting polymer particles fall into the container along a predetermined drop distance after dripping or shearing. The duration of the fall along the drop distance can serve to cool and influence the shape of the produced polymer particles. The aforementioned temperature control can be provided along the drop distance. For example, a portion of the drop distance can be provided for heating the produced polymer particles or for maintaining a predetermined temperature of the produced polymer particles. For example, this temperature can be in the range of a melting temperature of the polymer substrate used. Another portion of the drop distance can be provided for cooling the produced polymer particles below the glass transition temperature of the polymer substrate used. Therefore, temperature control zones can be provided along the drop distance, along which the falling, produced polymer particles are exposed to a temperature gradient.The upper limit temperature of a temperature gradient can be set to the melting temperature of the polymer substrate used, with the lower limit temperature of the temperature gradient corresponding to the glass transition temperature of the polymer substrate used. Thermal treatment of the produced polymer particles along the drop path can be used to influence the shape or shaping of the produced polymer particles.

[0103] The resulting polymer particles can be absorbed into a liquid contained in the container. The liquid can be temperature-controlled.

[0104] The shape of the produced polymer particles can be spherical, drop-shaped, cubic, or cylindrical. Irregular shapes of the polymer particles can also be part of the polymer particle standard if they are manufactured in this way. In addition to the already mentioned influencing factors such as droplet formation frequency and the conveying velocity of the polymer jet during shearing, as well as the shearing velocity or gas jet velocity during shearing, the shape of the polymer particles can be influenced by the shape of the cross-sectional area of ​​the nozzle outlet opening.

[0105] Use of a predetermined number of polymer particles produced from a polymer substrate according to the above process as a polymer particle standard for polymer particle analysis methods. In particular, the use of such polymer particle standards is intended for the polymer particle analysis of environmental samples. The use of polymer particle standards prepared from a predetermined number of polymer particles can also be intended for flow cytometry, Raman spectroscopy, Raman microscopy, laser diffraction particle size analysis, FT-IR, DSC, pyrolysis GC / MS, or thermal extraction desorption GC / MS (TED GC / MS).

[0106] Further details, features, and advantages of embodiments of the invention will become apparent from the following description of exemplary embodiments with reference to the accompanying drawings. They show:

[0107] Fig. 1: a schematic sectional view of an embodiment of a line unit of the device according to the invention,

[0108] Fig. 2: a schematic sectional view of a further embodiment of a line unit of the device according to the invention,

[0109] Fig. 3: the line unit shown in Figure 1 with a single doctor blade of a receiving component,

[0110] Fig. 4: the line unit shown in Figure 1 with a multiple doctor blade of a receiving component,

[0111] Fig. 5: the line unit shown in Figure 1 with a multiple doctor blade of a receiving component in an alternative embodiment,

[0112] Fig. 6: the line unit shown in Figure 1 with a gas nozzle of a receiving component and

[0113] Fig. 7: the line unit shown in Figure 1 with a rotatable roller of a receiving component.

[0114] Figure 1 shows a schematic sectional view of an embodiment of a line unit 1 of the device according to the invention. The line unit 1 is part of a supply component not shown in Figure 1, which, in addition to the line unit 1, also has means for storing and transporting a polymer substrate. In the exemplary embodiment shown, the line unit 1 has a tubular section and a nozzle-shaped section tapering towards a discharge opening 2. The discharge opening 2, which is formed on a nozzle opening side 3, has a diameter in the range between 0.02 mm and 0.2 mm. The nozzle opening side 3 has a flat surface in which the discharge opening is formed.

[0115] The line unit 1 has a plurality of first channels 5, which are formed circumferentially in the wall material of the line unit 1. The first channels 5 are part of a fluid-conducting temperature control unit (not shown). A heated liquid provided by the temperature control unit can flow through the first channels 5 and form a heating zone 4 at the nozzle-shaped section of the line unit 1. The heating zone 4 is provided to heat a polymer substrate 8 located in this region of the line unit 1 such that it is melted and can be discharged in this molten form via the discharge opening 2.

[0116] Furthermore, the line unit 1 has a plurality of second channels 7 formed circumferentially in the wall material, which are assigned to a cooling zone 6. The cooling zone 6 extends along the tubular section of the line unit 1. The second channels 7 are also part of the fluid-conducting temperature control unit. A coolant, which is provided by the temperature control unit at the desired temperature, can flow through the second channels 7 in order to cool the line unit 1 in the region of the cooling zone 6. This can be necessary in order to cool a polymer substrate 8 located in this region in the line unit 1. The cooling prevents liquefaction of the polymer substrate 8, so that it remains in a solid state, even if the pressure is increased in the direction of the discharge opening 2. The channels 5 and 7 can be designed such that a temperature gradient is generated along the line unit 1 in the direction of the discharge opening 2.

[0117] The inner diameter of the line unit 1 in the region of the cooling zone 6 corresponds to the outer diameter of a polymer substrate 8 fed in the feed direction 9, or the inner diameter of the line unit 1 is minimally larger than the outer diameter of the polymer substrate 8, in particular taking into account the expected thermal expansion of the not yet melted polymer substrate 8. In the example shown, the polymer substrate 8 is used in the form of a solid polymer substrate filament. This filament, which serves as raw material for the production of polymer particles, can be fed into the line unit 1 using a filament feed of a conveyor unit (not shown). The polymer substrate filament 8 has a self-sealing effect with respect to the inner wall of the line unit 1. In the solid state, the polymer substrate filament 8 serves as a piston, which can be moved in the direction of the discharge opening 2 using a conveyor unit (not shown).The feed direction is indicated by arrow 9. The pressure exerted thereby acts on the melt-liquefied polymer substrate 8 in the heating zone 4, so that the melt-liquefied polymer substrate 8 can exit through the discharge opening 2. By continuously advancing the polymer substrate filament 8, a continuous polymer substrate jet can be generated, which can be discharged via the discharge opening 2.

[0118] Figure 2 shows a schematic sectional view of a further embodiment of a line unit 1 of the device according to the invention.

[0119] In contrast to the line unit 1 shown in Figure 1, the line unit 1 shown in Figure 2 has a plurality of discharge openings 2 formed in the plane of the nozzle opening side 3. The discharge openings 2 can be arranged in a row or in a matrix. It should be noted that the figures are purely schematic and not to scale. The number of discharge openings 2 can vary depending on the dimensions of the line unit 1. For the purposes of the invention, a large number of discharge openings 2 is preferred in order to obtain a high number of polymer particles.

[0120] The line unit 1 has a plurality of first channels 5, which are formed circumferentially in the wall material of the line unit 1. The first channels 5 are assigned to the heating zone 4, which is located in the nozzle-shaped section of the line unit 1. A fluid provided by the temperature control unit can flow through the first channels 5 in order to heat this area in the line unit 1 and to melt or liquefy the polymer substrate 8 located there by applying heat.

[0121] Furthermore, the line unit 1 has a plurality of second channels 7 formed circumferentially in the wall material, which are assigned to a cooling zone 6. The cooling zone 6 extends along the tubular section of the line unit 1. The second channels 7 are also part of a fluid-conducting temperature control unit. A coolant can flow through the second channels 7, which is provided by the temperature control unit at the desired temperature in order to cool the line unit 1 in the region of the cooling zone 6.

[0122] In the embodiment of Figure 2, the polymer substrate 8 also seals off the inner wall of the line unit 1 in the region of the cooling zone 6 and can be used by the conveying unit as a piston within the line unit 1. The piston presses on the polymer substrate 8 liquefied in the heating zone 4, whereby the melt-liquefied polymer substrate 8 is pushed out of the line unit 1 through the discharge openings 2 of the line unit 1 in a feed direction 9. In this way, several parallel polymer streams can be generated at the discharge openings 2 of the line unit 1. With this multiple nozzle having several discharge openings 2, a doctor blade or a blade can be used to divide the polymer streams exiting through the discharge openings 2 into individual polymer particles. Further alternatively, it can be provided that an air stream divides the polymer streams exiting through the discharge openings 2 into individual polymer particles.

[0123] Figure 3 shows the line unit 1 shown in Figure 1 with a single doctor blade 10 of a receiving component.

[0124] The line unit 1 shown in Figure 3 corresponds to the line unit 1 shown in Figure 1, which is why a repeated description of the individual components is omitted and reference is made to the description of Figure 1.

[0125] On the nozzle opening side 3 of the line unit 1, a single doctor blade 10 associated with a receiving component is shown. This single doctor blade 10 is movable across the plane of the nozzle opening side 3 of the line unit 1 in the directions of movement 11 indicated by the double arrow. As a result of the back-and-forth movement of the single doctor blade 10, a polymer substrate jet discharged via the discharge opening 2 of the line unit 1 can be separated into individual polymer particles. The single doctor blade 10 causes the polymer particles to be sheared off at the discharge opening 2.

[0126] The polymer particles produced in this way can be collected in a container (not shown). This container is part of the receiving component.

[0127] Not shown is a control component with which the movement speed of the individual doctor blade 10 can be controlled as a function of the conveying volume of the polymer substrate 8 as a polymer substrate jet through the discharge opening 2.

[0128] The single doctor blade 10 can also be used in combination with the configuration of the line unit 1 shown in Figure 2. Figure 4 shows the line unit 1 shown in Figure 1 with a multiple doctor blade 12 of a receiving component.

[0129] The line unit 1 shown in Figure 4 also corresponds to the line unit 1 shown in Figure 1, which is why a repeated description of the individual components is omitted and reference is made to the description of Figure 1.

[0130] A multiple doctor blade 12 associated with a receiving component is shown on the nozzle opening side 3 of the line unit 1. This multiple doctor blade 12 comprises four doctor blades 12.1 rotating in the direction of movement 11, which are arranged uniformly on a rotating doctor blade shaft.

[0131] As a result of the rotation of the multiple doctor blade 12, the individual doctor blades 12.1 sweep over the nozzle opening side 3 of the line unit 1, thereby dividing a polymer substrate jet discharged through the discharge opening 2 into individual polymer particles. If necessary, the multiple doctor blade 12 can be moved axially or radially, for example, to maintain a defined distance from the nozzle opening side 3 of the line unit 1 or from the discharge opening 2.

[0132] The produced polymer particles can be collected in the receiving component in a collection container (not shown). The polymer particles, the receiving component, and the collection container are not shown in Figure 4.

[0133] The line unit i shown in Figure 4 can be aligned with its longitudinal axis horizontally. In this way, the polymer particles are separated, for example, by the doctor blade 12.1 moving from top to bottom across the nozzle opening side 3 and collected in a collecting container of the receiving component located below. In an alternative embodiment, the receiving component has a liquid bath (not shown) into which the formed micropolymer particles can fall.

[0134] Optionally, a scraper 13 can be arranged, which scrapes off the micropolymer particles separated by the doctor blades 12.1, which are still adhering to the doctor blades 12.1, and transfers them into a collecting container.

[0135] Not shown is a control component with which the rotation speed of the multiple doctor blade 12 can be controlled as a function of the conveying volume of the polymer substrate 8 through the discharge opening 2.

[0136] The multiple doctor blade 12 can also be used in combination with the design of the line unit 1 shown in Figure 2.

[0137] Figure 5 shows the line unit 1 shown in Figure 1 with a multiple doctor blade 12 of a receiving component in an alternative embodiment.

[0138] The line unit 1 shown in Figure 5 corresponds to the line unit 1 shown in Figure 1, which is why a repeated description of the individual components is omitted and reference is made to the description of Figure 1.

[0139] A multiple doctor blade 12 associated with a receiving component is assigned to the nozzle opening side 3 of the line unit 1. This multiple doctor blade 12 comprises, for example, two doctor blades 12.2 rotating horizontally in the direction of movement 11. The rotor axis of the multiple doctor blade 12 is aligned parallel to the longitudinal axis of the line unit 1.

[0140] The produced polymer particles are collected in the receiving component in a collection container (not shown). The polymer particles, the receiving component, and the collection container are not shown or are not fully shown in Figure 5.

[0141] Figure 6 shows the line unit 1 shown in Figure 1 with a gas nozzle 14 as a component of an embodiment of a device according to the invention.

[0142] The line unit 1 shown in Figure 6 corresponds to the line unit 1 shown in Figure 1, which is why a repeated description of the individual components is omitted and reference is made to the description of Figure 1.

[0143] In contrast to the separation units shown in Figures 3 to 5, which use doctor blades to separate a continuous polymer stream, in this embodiment a gas nozzle 14 is arranged next to the discharge opening 2 such that a gas stream or gas pulse is directed onto a polymer jet emerging from the discharge opening 2. The gas nozzle 14 can be arranged at an angle 15 to the continuous polymer stream discharged from the discharge opening 2. This angle 15 is formed between a longitudinal axis of the line unit 1 and a direction of the gas stream emerging from the gas nozzle 14. The angle 15, which can be in a range between 45° and 90°, is approximately 70° in the example in Figure 6.

[0144] The gas nozzle 14 can be used as a component of the separation unit with pulsed or continuous polymer substrate conveyance.

[0145] Figure 7 shows the line unit 1 shown in Figure 1 with a rotatable roller 16 of a receiving component. The rotatable roller 16 is assigned to the discharge opening 2 such that pulsed, isolated polymer particles can be deposited from the discharge opening 2 onto the surface of the rotatable roller 16. A scraper 17 is assigned to the rotatable roller 16, with which polymer particles deposited on the rotatable roller 16 can be scraped off. Produced polymer particles can be deposited separately onto the rotatable roller 16, with the rotatable roller 16 rotating by a predetermined angular step in the direction of the arrow. The scraper 17 is provided to release the produced, deposited polymer particles and scrapes across the roller surface as a result of the roller rotation. In this case, a collecting container (not shown) is assigned to the scraper 17, in which the detached polymer particles are collected or received.

[0146] The rotatable roller 16 can preferably be tempered in a range between 50 °C and 60 °C.

[0147] This design of the receiving component can be combined with a design of a nozzle with several discharge openings 2 as shown in Figure 2.

[0148] List of reference symbols

[0149] 1 line unit

[0150] 2 discharge opening

[0151] 3 Nozzle opening side

[0152] 4 heating zones

[0153] 5 first channels

[0154] 6 cooling zones

[0155] 7 second channels

[0156] 8 Polymer substrate

[0157] 9 Polymer feed direction

[0158] 10 single squeegees

[0159] 11 Direction of movement

[0160] 12 multiple doctor blades / doctor blade shaft

[0161] 12.1 Squeegee

[0162] 12.2 Squeegee

[0163] 13 scrapers

[0164] 14 Gas nozzle

[0165] 15 angles

[0166] 16 rotating rollers

[0167] 17 scrapers

Claims

Patent claims 1. Device for producing polymer particles, in particular micropolymer particles, from a polymer substrate (8), comprising a Provision component with at least one line unit (1) designed to convey the polymer substrate (8) through, which line unit has at least one nozzle with at least one discharge opening (2) for the polymer substrate (8) at its end, a temperature control unit with which the polymer substrate (8) can be temperature controlled at least in some areas along the line unit (1), and a conveying unit with which the polymer substrate (8) can be conveyed in a pulsed or continuous manner through the at least one discharge opening (2), further comprising a receiving component with a unit for receiving individualized polymer particles of the dispensed polymer substrate (8) conveyed in a pulsed manner through the at least one discharge opening (2) and / or a separation unit for separating the polymer substrate (8) conveyed continuously through the at least one discharge opening (2) into individual polymer particles.

2. Device according to claim 1, characterized in that the device has a control component with which the receiving component can be controlled as a function of the supply component.

3. Device according to claim 1, characterized in that the line unit (1) is designed as a narrowing pipe with a nozzle opening side (3), wherein the at least one discharge opening (2) is located on the nozzle opening side (3).

4. Device according to one of the preceding claims, characterized in that the conveying unit comprises an extruder, which is arranged in the line unit. Device according to one of claims 1 to 3, characterized in that the conveying unit has a filament feed with which a polymer substrate filament can be conveyed into the line unit (1). Device according to one of the preceding claims, characterized in that the tempering unit has a means for cooling and a means for heating, wherein the means for cooling is assigned to a cooling zone (6) and the means for heating is assigned to a heating zone (4), wherein the cooling zone (6) and the heating zone (4) are arranged along the line unit (1). Device according to one of the preceding claims, characterized in that the means for cooling and / or the means for heating is an electrical means or a means operating with a thermally conductive tempering fluid.Device according to one of the preceding claims, characterized in that the temperature control unit has fluid-carrying channels, wherein circumferential first channels (5) for a first temperature control fluid are arranged in a wall of the line unit (1), wherein the first channels (5) are assigned to the heating zone (4), and that circumferential second channels (7) for a second temperature control fluid are arranged in the wall of the line unit (1), wherein the second channels (7) are assigned to the cooling zone (6). Device according to one of the preceding claims, characterized in that the heating zone (4) is arranged in a region of the discharge opening (2) of the line unit (1), wherein the cooling zone (6) is arranged at a distance from the region of the discharge opening (2) of the line unit (1). Device according to one of claims 1 to 9, characterized in that the line unit (1) has a plurality of discharge openings (2), wherein the discharge openings (2) are arranged in a row or in the form of a matrix with a plurality of rows and a plurality of columns. Device according to one of claims 1 to 10, characterized in that the receiving component, as a unit for receiving individualized polymer particles conveyed in a pulsed manner through the at least one discharge opening (2), comprises a plate arranged opposite the at least one discharge opening (2) for depositing generated polymer particles. Device according to the preceding claim, characterized in that the surface of the plate or the plate as such can preferably be temperature-controlled in a range between 50°C and 60°C.Device according to one of claims 11 or 12, characterized in that the plate is elastic and / or has a non-stick coating or is formed from a non-stick material. Device according to one of claims 1 to 10, characterized in that the receiving component, as a unit for receiving individualized polymer particles conveyed in a pulsed manner through the at least one discharge opening (2), comprises a rotatable roller (16) arranged opposite the at least one discharge opening (2) for depositing generated polymer particles, wherein the rotatable roller (16) is assigned a stripper (17) with which polymer particles deposited on the rotatable roller (16) can be stripped off. Device according to the preceding claim, characterized in that the rotatable roller (16) can preferably be tempered in a range between 50 °C and 60 °C. Device according to one of claims 1 to 15, characterized in that the discharge opening (2) has a diameter in the range of 0.02 mm to 0.2 mm. Device according to one of claims 1 to 16, characterized in that the at least one discharge opening (2) has a round, elliptical, rectangular, triangular or star-shaped cross-section. Device according to one of claims 1 to 17, characterized in that the separating unit comprises a single doctor blade (10) which is used to shear off the at least one discharge opening (2) emerging polymer substrate (8) at a predetermined speed over the at least one Discharge opening (2) is movable back and forth. Device according to one of claims 1 to 17, characterized in that the separation unit comprises a doctor blade shaft (12) having a plurality of doctor blades (12.1), wherein the doctor blade shaft (12) is rotatably arranged such that the doctor blades (12.1) brush over the at least one discharge opening (2) when the doctor blade shaft (12) rotates. Device according to one of claims 1 to 17, characterized in that the separation unit comprises at least one gas nozzle (14) which is assigned to the at least one discharge opening (2), wherein a directed gas jet can be discharged with the gas nozzle (14) onto the polymer substrate emerging at the at least one discharge opening (2). Device according to one of claims 1 to 20, characterized in that characterized in that the control component is configured to control a reciprocating movement of the individual doctor blade (10), a rotation of the doctor blade shaft (12), and / or a gas ejection frequency of the gas nozzle (14) as a function of the conveying speed of the polymer substrate (8) through the at least one discharge opening (2). Device according to one of claims 1 to 21, further comprising a device for thermally treating produced polymer particles. A method for producing polymer particles, in particular micropolymer particles, with a predetermined particle shape and a predetermined particle size, wherein the polymer particles are provided by dripping a polymer substrate by means of a nozzle or shearing off a polymer jet of the polymer substrate conveyed through a nozzle, the method comprising the following steps: Providing the polymer substrate in a molten form, dropletizing the molten polymer substrate to produce individual polymer particles, wherein the particle shape and particle size are controlled by controlling the drop volume and the drop discharge speed, or alternatively shearing a continuously conveyed polymer jet of the molten polymer substrate to produce individual polymer particles, wherein the particle shape and particle size are controlled by controlling the shear width and shear speed of the polymer jet as a function of a conveying speed of the polymer jet of the molten polymer substrate, Collecting the separated polymer particles in a container, and checking the number of polymer particles provided. Method according to claim 23, characterized in that the dropwise separation of the flowable polymer substrate into individual polymer particles by applying vertical mechanical vibrations to the flowable polymer substrate in a range from 10 Hz to 400 kHz. Method according to the preceding claim, characterized in that the vibrations are generated using a piezo element. Method according to one of claims 24 or 25, characterized in that the number of polymer particles generated is checked based on the number of fully completed vibrations. Method according to claim 23, characterized in that the shearing is carried out using a doctor blade guided over a discharge opening of the nozzle or using a pulsed gas jet from a gas nozzle. Method according to the preceding claim, characterized in that the number of polymer particles is checked based on the number of doctor blade movements carried out or based on the number of gas jets carried out.Method according to one of the preceding claims, characterized in that the polymer particles are produced from a polymer substrate selected from a group consisting of polyethylene (PE), polypropylene (PP), polyvinyl chloride (PVC), polystyrene (PS), polycaprolactone (PCL), polylactide (PLA), acrylonitrile-butadiene-styrene copolymer (ABS), acrylonitrile-styrene-acrylate copolymer (ASA), and thermoplastic polyurethane (TPU). Method according to one of the preceding claims, characterized in that the polymer substrate is heated and / or subjected to a compressive force during preparation, preferably extruded, to obtain the molten polymer substrate. Method according to one of the preceding claims, characterized in that a diameter of the polymer particles produced is set between 0.02 mm and 2.0 mm. Method according to one of the preceding claims, characterized in that the polymer particles obtained are immediately tempered after droplet formation or shearing, preferably tempered below the glass transition temperature of the polymer substrate used. Method according to one of the preceding claims, characterized in that the polymer particles obtained fall into the container along a predetermined falling distance after droplet formation or shearing. Method according to one of the preceding claims, characterized in that the polymer particles obtained are taken up in a liquid. Method according to one of the preceding claims, characterized in that the polymer particles obtained are subjected to a heat treatment before they reach the container.Use of a predetermined number of polymer particles produced by a method according to any one of claims 23 to 35 as a polymer particle standard in the polymer particle analysis of environmental samples. Use of a predetermined number of polymer particles produced by a method according to any one of claims 23 to 35 as a polymer particle standard in flow cytometry, Raman spectroscopy, Raman microscopy, or laser diffraction. Particle size analysis, FT-IR, DSC, Pyrolysis-GC / MS, Thermal- Extraction-Desorption-GC / MS (TED-GC / MS).

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