RU2805333C2 - Method and device for preparation, processing and/or recycling of materials - Google Patents

Abstract

FIELD: monitoring technological processes by optical means.
SUBSTANCE: invention concerns a method for preparing thermoplastic materials for reuse. When implementing the method, the thermoplastic material is moved and mixed, as well as crushed and softened in the receiving hopper, spectroscopic and/or spectrometric measurements of the lumpy or particle-shaped material moving in the receiving hopper are performed and the quantitative and qualitative parameters of the specified material or changes in these parameters are determined. During measurements, the material is excited by electromagnetic radiation with light in the infrared, visible and/or UV range. The exciting electromagnetic radiation is focused to a point that lies inside the receiving hopper on the hopper wall or directly behind the hopper wall or at a maximum distance of 10 cm behind the hopper wall. In this case, electromagnetic radiation excites a volume determined by the cross-sectional area of the measuring spot in the range of 0.1-5 mm and with a penetration depth into the material of 0.3-30 microns.

EFFECT: simplifying the control method and improving the quality of the resulting product.

31 cl, 12 dwg, 3 tbl, 3 ex

Description

The invention relates to a method for preparing, processing or recycling materials, in particular thermoplastic materials, according to claim 1 of the formula. In addition, the invention relates to a device for implementing the proposed method according to claim 15 of the formula.

In particular, when recycling plastics, the main challenge is the processing of plastics from different sources with possibly different, under certain circumstances, composition, which may also be unknown. The field of plastics recycling includes, for example, both internal plastic waste and used plastic products such as packaging, computer cases, or car parts, etc., so that the starting materials have, for example, highly variable filler contents and polymers.

The purpose of the preparation is to achieve certain quality characteristics for the reuse of the material, for example certain mechanical, optical and/or other properties. In order to achieve these quality attributes, in addition to the required machine technical conditions, an analysis of incoming and processed materials is also necessary.

The object of the invention is to provide a method and apparatus for the preparation, processing and/or recycling of materials, such as thermoplastic materials, which would allow the preparation of materials in a simple manner while simultaneously being able to monitor and control the preparation process to achieve the desired quality attributes of the final product.

This problem is solved, according to the invention, by means of a method with the features of claim 1 of the formula. Moreover, according to the invention, it is provided that

- the material is moved and mixed in the receiving hopper, in particular the cutting compactor or pre-processing unit (PCU), and, if necessary, also heated, crushed and/or softened, the material remaining in the receiving hopper mostly in lump or particulate form and in an unmolten state, and

- the lumpy or particulate material moving in the receiving hopper is analyzed or measured inline spectroscopically and/or spectrometrically, and the measured values thus obtained are used to obtain information about the correspondingly measured material, in particular about the quantitative and/or qualitative parameters of the corresponding material.

By means of this embodiment of the proposed method, it is possible to examine the material moving in the receiving hopper using a spectroscopic and/or in-line spectrometric method and thus obtain information about the material, for example about the content of additives or fillers and the composition of the polymer, so that the processing process can be controlled in accordance with the information, for example by adding fillers or polymers. This makes it possible to accurately determine the desired quality attributes or properties of the final product.

In this case, “inline” means that the material analysis or measurement system in the receiving hopper is built into the preparation or processing technological line and the analysis or measurement occurs directly on the line during the preparation or processing of the material.

It does not matter what type of processed material we are talking about. The proposed method and device can also be used for the preparation, processing and/or recycling of, for example, food particles, wood, paper or rock, if the lump or particulate material particles generally behave like a flowable material, i.e. are in constant motion. In this case, the direction of movement does not matter. Thus, the particles can move in the receiving hopper, for example, in the forward direction through it and in the radial direction of the rotating mixing and/or grinding tools.

Particularly accurate examination of the material located in the receiving hopper can be achieved when at least parts of the material located inside the receiving hopper and the lump or particulate material rotating there are excited due to physical influence, in particular due to electromagnetic radiation, and arise as a reaction on the influence of measuring signals, in particular the characteristic spectra of electromagnetic radiation scattered on the material being measured, are detected preferably by a spectrometric method.

In order to be able to use a large number of different physical processes to identify chemical substances when measuring or analyzing the material in the receiving hopper, it can be provided that the spectroscopic and/or spectrometric measurement takes place by means of atomic or molecular spectroscopy. This could involve, for example, Raman spectroscopy, NIR, UV/VIS, fluorescence and/or absorption spectroscopy.

In order to ensure a particularly targeted use of the Raman effect, in which light energy is transferred to matter and back, it can be provided that light in the IR, visible and/or UV range is used for excitation. In this case, in particular light with a wavelength in the range 100-1400 nm, preferably 500-1000 nm, can be used. Additionally or alternatively, excitation with a laser is possible, in particular in the wavelength range 100-1400 nm, and/or with a power in the range 15 mW - 5 W, preferably 100-500 mW.

Particularly simple and targeted control of the physical properties or quality attributes of the final product can be achieved when the detected light is analyzed in order to determine in-line specific quantitative and/or qualitative parameters of the material, in particular thermoplastic material, or changes in these parameters during the process. This information or these parameters can be used advantageously to monitor and/or control the process and/or to control the operation of the process in the receiving hopper. This means that a direct response to changes in parameters during material preparation is possible, for example by adding fillers, so that the properties of the final product can be specifically controlled.

So that the detected measuring signals can be measured in particularly good quality, i.e. with little background noise, and to make the excitation source emitting the exciting electromagnetic radiation as small as possible, it can be provided that the electromagnetic radiation exciting the material is focused onto a focal point that lies inside the receiving hopper on or directly behind the hopper wall, preferably at a distance of maximum 10 cm behind the wall of the bunker.

In order to ensure particularly reliably when detecting measuring signals that they are not influenced by surface contamination or the coating of the measured material particles, it can be provided that due to physical influence, in particular electromagnetic radiation, a volume is excited, determined by the cross-sectional area of the measuring spot of 0.1- 5 mm, in particular 1-3 mm, and a depth of penetration into the material of 0.3-30 microns, in particular 8-15 microns.

In this way, individual particles can be examined, with the excitation reaching deep areas of the corresponding particle that are not covered, for example, by paint, so that a representative measured value for the particle can be obtained.

In order to particularly reliably ensure that the material being measured is sufficiently excited by the physical action and to prevent extraneous light from influencing the measurement, it can be provided that the physical action exciting the material, in particular electromagnetic radiation, is introduced into the receiving hopper or into the material in one or more of the following positions:

- below the level of filling of the receiving hopper with material/material particles during operation,

- at a height and/or at a distance from the bottom or from a mixing and/or grinding tool, at which physical impact, in particular electromagnetic radiation, occurs constantly below the filling level specified, according to the method, for particles of material located or rotating in the receiving hopper and/or below the level of the mixing clot formed during the movement and/or rotation of material particles,

- at the height of the middle third of the filling level specified, according to the method, for the material in the receiving hopper and/or the mixing clot,

- in the area of the receiving hopper, in which the density of moving and/or rotating particles of material is greatest, and/or

- in the area of the receiving hopper, in which moving and/or rotating particles of material exert the greatest pressure on the side wall of the receiving hopper.

Particularly frequent and regular replacement of material at the measuring position or at the focal point can be achieved when the lump or particulate material has a direction of movement in the outer area of the receiving hopper, in particular on its side wall, in the direction of the periphery and/or a direction preferably directed upwards movements.

Another improvement in material replacement at the measuring position or focal point can be achieved when the lump or particulate material is rotated radially at a speed of 0.3-45 m/s and/or vertically at a speed of 0.1-60 m/s . In this way, it is possible to achieve frequent and regular replacement of lump or particulate material in the outer area of the receiving hopper, in particular on its side wall.

A particularly accurate possibility of outputting information about the material located inside the receiving hopper can be ensured when the lump or particulate material located inside the receiving hopper and rotating there, in particular individual particles of material, is excited at a large number of specified moments of time by a physical influence, in particular electromagnetic radiation, and an average value of information about the correspondingly measured material, in particular about individual particles, is determined and made available. In this case, we can preferably talk about the average value of quantitative and/or qualitative parameters of the corresponding material or corresponding particles, which were determined on the basis of selected, preferably all, measured values obtained at these points in time. Consequently, an average of the measured values of the individual measured particles arises.

Another particularly precise possibility of obtaining information about the material located inside the receiving hopper, in which at the same time the physical impact emitted by an excitation source of particularly low power is also sufficient, can be provided when the material located inside the receiving hopper and rotating therein is lumpy or in the form of particles for a given period of time. period of time, in particular several seconds, is continuously excited by physical influence, in particular electromagnetic radiation. In the corresponding period of time, on the basis of the measured values continuously obtained within this period of time, general information about the correspondingly measured material, in particular a quantitative and/or qualitative parameter, is calculated and made available. Consequently, there is an accumulated measured value for all particles that moved past the measurement position or focal point during the measurement time.

In order to be able to particularly effectively correct effects caused by temperature changes that could distort the measuring signals coming from the material being measured or the associated material information, it can be provided that the temperature inside the receiving hopper and/or the temperature of the material is measured and information about temperature. The measured temperature information can serve as an indicator for correcting information about the correspondingly measured material, in particular the quantitative and/or qualitative parameters of the corresponding material. Additionally or alternatively, the temperature of the material can be recorded and used as a reference for adjusting the spectra.

A particularly accurate assessment of the information obtained for a material can be ensured when reference information, in particular quantitative and/or qualitative reference parameters, preferably reference spectra, is stored and the information obtained for a correspondingly measured material, in particular parameters, preferably spectra, is compared with the reference information, in particular reference parameters, preferably reference spectra. Deviations from reference information, in particular reference parameters, preferably reference spectra, can thus be determined particularly simply and, in particular, displayed and/or used for monitoring and/or control of the process in the receiving hopper and/or the subsequent process chain.

The objective of the invention is further to create a device for implementing the proposed method for the preparation, processing and/or recycling of materials, in particular thermoplastic materials. This problem is solved by means of a device with the features of claim 15 of the formula.

Moreover, according to the invention, it is provided that the device contains a receiving hopper, in particular a cutting compactor and/or a pre-treatment unit (PCU), a mixing and/or grinding device for the material, as well as a spectroscopic and/or spectrometric measuring device for analyzing the material moving inside receiving hopper for lump or particulate material or to obtain information about the correspondingly measured material, in particular the quantitative and/or qualitative parameters of the corresponding material.

Due to this embodiment of the proposed device, it is possible to carry out in-line spectroscopic and/or spectrometric measurement or analysis of the material moving in the receiving hopper. Thus, information about the material, such as the content of additives or fillers and the composition of polymers, can be obtained online, so that the processing process can be controlled in accordance with the information to fine-tune the desired quality attributes or properties of the final product, for example by adding fillers or polymers.

A particularly compact version of the proposed device, which provides in-line measurement and analysis of the processed material, can be created when it contains at least one receiving hopper, in particular a cutting compactor, with a mixing and/or grinding device for the material at least one spectroscopic and/or spectrometric measuring device for inline measurement of parts of lumpy or particulate material moving inside the receiving hopper and a processing and control unit connected to the measuring device with the ability to exchange data.

In this case, the measuring device is preferably designed to transmit a physical influence, in particular electromagnetic radiation, to excite a rotating lump or particulate material and detect, preferably by a spectrometric method, measuring signals arising as a response to the influence, in particular the characteristic spectra of scattered on the measured material of electromagnetic radiation.

In this case, the processing and control unit is preferably designed to control the measuring device of the transmitted physical influence, in particular electromagnetic radiation, detect the resulting measuring signals, make available the measured values obtained in this way and, if necessary, based on the obtained measured values, output and provide disposition of information about the correspondingly measured material, in particular the quantitative and/or qualitative parameters of the corresponding material.

A receiving hopper, particularly suitable for the preparation, processing or recycling of materials, can be designed to include a side wall and be substantially conical or cylindrical, or have a conical or cylindrical wall section and, if necessary, a bottom.

Particularly effective preparation of a wide variety of materials can be ensured when at least one mixing and/or grinding tool for moving and mixing and rotating, in particular around a vertical axis of rotation, is arranged in the receiving hopper as a mixing and/or grinding device. , if necessary, also for heating, crushing and/or softening the processed lumpy or particulate material, and during operation a vortex and/or mixing clot is formed in the receiving hopper.

In applications where too much mixing of the particles is not desired, it can be advantageously achieved that the material forms a vortex and rotates substantially only in one plane, while along the longitudinal axis of the receiving hopper the material flows, for example, at a speed of 2 m /h at a peripheral speed of, for example, about 0.3 m/s. In applications where particularly good mixing is desired, a mixing clot can be formed.

Particularly effective preparation of the material located in the receiving hopper can be achieved when the peripheral speed of the mixing and/or grinding tool is selected so that the lump or particulate material rotates radially at a speed of 0.3-45 m/s and/or in the vertical direction - at a speed of 0.1-60 m/s. This advantageously also ensures that the material is always replaced at the measuring position or focal point.

Particularly simple unloading of the prepared material from the receiving hopper can be ensured when an opening is made in the receiving hopper, in particular in its side wall, through which the pre-treated polymer is discharged from the receiving hopper, and when at least one conveyor is located, in particular an extruder with at least one rotating screw in the housing, in particular a plasticizing or agglomerating screw, for capturing the pre-processed material emerging from the hole.

To further simplify unloading, the opening in the receiving hopper may be located at the height of the mixing and/or grinding tool closest to the bottom or the lowest, and the housing may have on its end side or in the side wall a feed hole for the material captured by the auger, which communicates with the hole.

A particularly compact version of the measuring device can be created when it contains at least one active or directed inside the receiving hopper excitation source for transmitting a physical effect, in particular the emission of electromagnetic radiation, to at least part of the inside of the receiving hopper and a piece of material rotating there or in the form of particles, as well as at least one detector, in particular a spectroscope, for recording measurement signals arising as a reaction to the influence, in particular for recording the characteristic spectra of electromagnetic radiation scattered on the measured material.

In this case, the excitation source can act, for example, from the wall of the receiving hopper or from a mixing and/or grinding tool, or from the bottom of the receiving hopper into it.

Particularly reliable characterization of the material located in the receiving hopper can be achieved when the processing and control unit is designed for spectrometric and/or spectroscopic analysis of the measuring signals arising as a reaction to the influence, in particular the analysis of the characteristic spectra of electromagnetic radiation scattered on the measured material.

A particularly simple way to avoid interfering influences coming from the receiving hopper on the excitation source and/or on the detector of the measuring device can be created when the excitation source and/or detector and/or processing and control unit are physically separated from the receiving hopper or connected to it without vibrations , in particular via fiber optic systems and/or light guides.

In order to be able to use a wide variety of physical processes for excitation and chemical analysis of the material located in the receiving hopper, it can be provided that the measuring device comprises a device, in particular a detector, for atomic or molecular spectroscopy, in particular for Raman spectroscopy, NIR, UV/ VISUAL, fluorescence and/or absorption spectroscopy.

In order to be able to analyze or characterize the material inside the receiving hopper by means of its response to light in different wavelength ranges, it can be provided that the excitation source is configured to emit light in the region of infrared, visible and/or UV light, in particular in range 100-1400 nm, preferably 500-1050 nm.

An excitation source of particularly versatile use can be created when it is a laser, in particular with a wavelength range of 100-1400 nm and/or a power in the range of 15 mW - 5 W, preferably 100-500 mW.

Particularly reliable measurement of materials inside the receiving hopper while simultaneously physically separating it from the measuring device, so that the latter is largely unaffected by interfering influences coming from the receiving hopper, can be achieved when a at least one measuring hole. Moreover, it is designed in such a way that the physical effect created by the excitation source, in particular the emitted electromagnetic radiation, affects the material in the receiving hopper, and the scattered light from the receiving hopper is detected outside it.

A measuring opening that causes particularly small design changes on the receiving hopper, which could cause its static weakening, can be created when the measuring opening is closed by a window made of a material that is permeable, in particular to electromagnetic radiation, such as sapphire glass.

In order to ensure that the measuring signals coming from the material inside the material receiving hopper are distorted as little as possible, it can further be provided that the window has a thickness of 1-100 mm.

In order to influence the stability of the receiving hopper as little as possible due to the position of the window or measuring opening, it can be provided that the surfaces of the window are level and oriented parallel to each other. Alternatively, this effect can be achieved when the inner surface of the window facing the receiving hopper is made concave in accordance with the radius of the receiving hopper, and the outer surface of the window facing away from it is concave parallel to the inner surface.

In order to achieve particularly reliable transport of a sufficient amount of material past the measuring opening, it can be provided that at least one measuring opening, in particular in the side wall of the receiving hopper, is located in one or more of the following positions:

- in the height zone of the lowest mixing and/or grinding tool closest to the bottom, in particular slightly above or below it, preferably at the shortest distance between the extreme point of the mixing and/or grinding tool and the side wall, and/or

- in the area of the lower third of the height of the receiving hopper.

A particularly advantageous positioning of the measuring opening, which allows a particularly precise analysis or measurement of the material located inside the receiving hopper, can be achieved when at least one measuring opening, in particular in the side wall of the receiving hopper, is located in one or more of the following positions:

- below the filling level for the material or its particles located in the receiving hopper during operation,

- at a height and/or at a distance from the bottom or from the mixing and/or grinding tool, on which the physical impact, in particular electromagnetic radiation, lies constantly below the specified, according to the method, level of filling of particles of material located or rotating in the receiving hopper and /or the level of the mixing clot formed during their movement and/or rotation,

- at the height of the middle third of the level of filling of material in the receiving hopper and/or mixing clot specified according to the method,

- in the area of the receiving hopper, in which the density of moving and/or rotating particles of material is greatest, and/or

- in the area of the receiving hopper, in which moving and/or rotating particles of material exert the greatest pressure on the side wall of the receiving hopper.

In all these positions it is guaranteed that sufficiently frequently changing material will move past the measuring hole and that extraneous light will not have any influence on the measurement.

A particularly small influence on the measuring signals coming from the measured material due to, for example, coatings or contamination of the surface of its particles can be achieved when the volume range excited by physical influence, in particular electromagnetic radiation, is determined by the cross-sectional area of the measuring spot of 0.1-5 mm, in particular 1-3 mm, and a depth of penetration into the material of 0.3-30 microns, in particular 8-15 microns.

A particularly optimal signal-to-noise ratio of the measuring signals can be achieved when a lens or lens system is provided for focusing the electromagnetic radiation of the excitation source onto a focal point, the focal point being formed in particular on or directly behind the window, preferably at a distance of maximum 10 cm behind it .

Particularly targeted control of processes for the preparation and recycling of materials, in particular thermoplastic materials, can be achieved when the processing and control unit interacts with the process control unit with the possibility of data exchange. Such a process control unit is preferably designed so that the data transmitted by the processing and control unit, in particular information about the correspondingly measured material, preferably quantitative and/or qualitative parameters of the corresponding material, can be used to monitor and/or control the process in the receiving hopper and/or subsequent technological chain.

Particularly effective control of quality attributes or desired, for example optical or physical properties, of the final product can be ensured when the process control unit is configured to carry out

- dosing of fillers into the receiving hopper and/or

- supply of materials, in particular polymers, into the receiving hopper and/or into the unloading device connected to it and/or

- unload processed materials, in particular granules, from the receiving hopper using an unloading device attached to it.

A particularly simple calculation of the influence of temperature on the measuring signals generated by the measured material can be achieved when at least one temperature measuring device is provided upstream of the processing and control unit. Such a temperature measuring device is designed to measure the temperature inside the receiving hopper and/or the temperature of the material and transmit it to the processing and control unit. In this case, the processing and control unit is designed to use the values measured by at least one temperature measuring device to correct the influence of temperature on the information obtained for the correspondingly measured material, in particular the temperature-dependent characteristic spectra of electromagnetic radiation scattered on the measured material, and make available the information thus corrected, in particular the spectra.

Particularly precise correction of temperature influences can be achieved when the temperature measuring device is located in the receiving hopper at the same height, in particular in the same position, as the at least one measuring opening.

The possibility of obtaining particularly reliable information about the material located inside the receiving hopper can be created when the processing and control unit is configured to

- control the measuring device, in particular the excitation source, at a large number of specified times and repeatedly transmit a physical effect, in particular emit electromagnetic radiation, and

- calculate and make available the average value of information about the correspondingly measured material, in particular about the individual measured particles, preferably quantitative and/or qualitative parameters of the corresponding material, which were obtained on the basis of selected, preferably all, measured values obtained at these points in time by the measuring device device, in particular a detector.

Another possibility of obtaining particularly reliable information about the material inside the receiving hopper, in which an excitation source of particularly low power is preferably sufficient, can be created when the processing and control unit is configured to

- control a measuring device, in particular an excitation source, and continuously exert a physical influence, in particular emitting electromagnetic radiation, for a given period of time, in particular several seconds, and

- calculate and make available, in an appropriate period of time, general information about the correspondingly measured material, in particular a quantitative and/or qualitative parameter, on the basis of the measured values continuously obtained by the measuring device, in particular the detector, during this period of time.

Another simple assessment or analysis of information detected by the processing and control unit, for example spectra, can be provided when the processing and control unit contains a memory, wherein the memory stores reference information, in particular quantitative and/or qualitative reference parameters, preferably reference spectra, and the processing and control unit is configured to compare the information obtained for the correspondingly measured material, in particular parameters, preferably spectra, with reference information, in particular reference parameters, preferably reference spectra, to determine the deviation from the reference information, in particular reference parameters, preferably reference spectra, and in particular transmitted to the process control unit and/or to the display unit.

In this case, a measuring device is understood as a device for recording and displaying and quantitative and/or qualitative analysis of a spectrum, containing an excitation source and a detector. In this case, the excitation source and detector are coordinated with each other. Such a measuring device can be a spectrometer.

In this case, a detector is understood as a device for detecting and decomposing radiation or other physical measured values into a spectrum, which is integrated into the measuring device. With such a detector we can talk about a spectroscope.

Other advantages and embodiments of the invention are set forth in the description and in the accompanying drawings.

The invention is schematically illustrated in the drawings and described with reference to them below with the help of particularly preferred examples of its implementation, which should not be construed as limiting.

On the drawings:

- fig. 1: an example of the proposed device for the preparation, processing and/or recycling of materials, in particular thermoplastic materials, with a Raman spectrometer attached to the receiving hopper;

- fig. 2: example of the device from FIG. 1 with temperature measuring device;

- fig. 3a, 3b, 4: other examples of connecting the measuring device to the receiving hopper;

- fig. 5, 6: examples of Stokes and anti-Stokes lines at different wavelengths;

- fig. 7: recorded spectra of low-density polyethylene (HDPE) with different contents of CaCO ₃ as a filler;

- fig. 8: derived from the spectra in FIG. 7 fluctuation of CaCO ₃ content during the process duration;

- fig. 9: recorded spectra of different compositions for mixtures of PP and PE;

- fig. 10: obtained using the spectra from FIG. 9 contents of PP and PE for different moments of measurement;

- fig. 11: obtained using spectra of PA and PE contents for different measurement moments.

General information

The main part of the preparation of thermoplastic or partially thermoplastic materials is the operation of a combination of cutting compactor and extruder, i.e. The design of the cutting compactor, the so-called “pre-processing unit” (PCU), with the extruder is taken over by the cutting compactor. Such a cutting compactor or such a pre-processing unit PCU is hereinafter called receiving hopper 1.

The receiving hopper 1 is a generally cylindrical tank, which can contain a mixing and/or grinding device, i.e., for example, mixing and cutting rotating tools, which are preferably installed below or from the one closest to the conveyor, for example extruder 5, points up. Tools can be made as cutting tools, stirring tools, mixing tools, or combinations thereof. Such devices are known, for example, from EP 2689908 B1 or EP 2525953 B1 or EP 123771.

The processed material behaves essentially like a fluid. It is either already lumpy, or is brought into such a lumpy shape by tools. By cutting, stirring and/or mixing, energy is introduced into the material and the material is heated evenly, and regardless of the thickness of the material particles, complete heating should be achieved. Due to softening and restoration of stretching, the bulk density can increase. Further, due to heating, a precondition is created that more volatile substances, which are partly undesirable, can evaporate. In addition, depending on the type of thermoplastic polymer, changes in structure may occur, i.e. change in crystallization.

The finished prepared material can then be discharged from the receiving hopper 1 either continuously or in batches. Suitable discharge devices or conveyors include gates, conveyor screws or extruder screws positioned so that the material is discharged at least by pure centrifugal force. However, forced unloading by tipping or turning over is also possible. In addition, a transport tool can also be placed in the receiving hopper 1 and the pre-processed material can be discharged. For continuous operation, continuous material discharge is the preferred option.

Physical methods based on the interaction between physical influences, such as electromagnetic radiation, and matter, and examining the energy spectrum of a sample using radiation or waves, such as frequency spectrum analysis methods such as NIR, Raman, NIR spectroscopy, etc. have long been discussed in the field of plastic recycling. In connection with the invention, such physical methods are understood to mean methods for identifying chemical substances by physical stimulation, for example with a laser. As a result of this excitation, processes such as rotational, vibrational, photonic or spin-flip processes are excited, which lead to changes in charge carrier density, which can be used to identify chemical substances.

In part, such physical methods are used in sorting processes for recycling plastics. For example, optical sorting processes use FT/NIR spectroscopy to separate different types of plastics. Basically, there is lumpy separated material that is sorted according to the good/bad principle. Similar systems are used in the laboratory or for material identification in the form of hand-held instruments.

In extrusion technology, such methods have so far been used to characterize the melt and properties on a trial basis only for components, because statistical premises, i.e. small measurement range, long measurement time, slight homogenization of polymer mixtures, small penetration depth into the melt, and adhesion to the walls that occurs with many polymers, i.e. the material is not replaced, information is allowed to an acceptable extent, preferably only about a single polymer.

In contrast to the use of spectrometric measuring systems when sorting raw flakes or from polymer melts in an extruder, in cut-and-seal systems, i.e. in the case of hot, softened, but always lumpy, unmelted particles of material, and also rapidly rotating in a tank at a forced changing temperature, such spectrometric measurements for on-line monitoring of the process and, if necessary, control it due to the above-mentioned limitations are still not possible were applied.

Measuring systems of physical methods based on the interaction between physical influences, for example electromagnetic radiation, and matter, and examining the energy spectrum of a sample using radiation or waves, are mainly volumetric measuring systems that, due to excitation, for example laser or infrared light , the spectra reflected from the material are recorded and either directly evaluated or coordinated with libraries. For this reason, the measurement frequency and the recorded “volume range” have a representative influence on the achieved measurement result.

An example of such a physical method is Raman spectroscopy. Some of its basic principles are briefly explained below.

In order for Raman spectroscopy to be applied to molecules, the polarizability must change when the molecule rotates or vibrates. In Raman spectroscopy, the matter being studied is irradiated with monochromatic light, usually laser light. In the spectrum of light scattered on a sample, in addition to the penetrated frequency (Rayleigh scattering), other frequencies are also observed. The frequency differences of the penetrated light correspond to the energies of rotational, vibrational, photonic or spin-flip processes characteristic of the material. Based on the obtained spectrum, similar to the spectra of infrared spectroscopy, one can draw a conclusion about the substance under study. The lines appearing in the Raman spectrum are also called Stokes or anti-Stokes lines.

The reason is the interaction of light with matter, the so-called Raman effect, in which energy is transferred by light to matter (the “Stokes side” of the spectrum) or energy is transferred by matter to light (the “anti-Stokes side” of the spectrum). Since the wavelength of light, i.e. its color depends on the energy of the light, this energy transfer causes a shift in the wavelength of the scattered light relative to the transmitted light, the so-called Raman shift. According to the spectrum, i.e. frequency and the corresponding intensity and polarization of the scattered light, the following material properties can be inferred, among others: crystallinity, crystal orientation, composition, deformation, temperature, doping and relaxation.

Raman scattering of molecules usually has a very small scattering cross section, for example about 10 ^-30 cm ² . The scattering cross section is a measure of the probability that a measured molecule will interact with incident radiation or an incident particle. Therefore, in the case of small scattering cross sections, a relatively high concentration of molecules or high laser intensity is required, i.e. a large number of particles to obtain a detectable signal. Thus, Raman spectra cannot be obtained for some molecules.

In order to be able to prepare materials, such as plastics, from different sources and/or different compositions, so that certain quality attributes are achieved for reuse, for example mechanical and/or optical properties, in addition to the necessary machine-technical prerequisites, an analysis of incoming as well as recycled materials is necessary. materials.

For such analysis, measuring devices are preferably used, which, in particular,

- can provide absolute values,

- easy to calibrate, maintain and control,

- can be integrated online into the machine,

- made reliable for round-the-clock operation 365 days a year,

- must be integrated into the machine control,

- can flexibly install various unknown material components.

Furthermore, it must be possible to cover several measuring locations in a plant with the system, and economic aspects such as the cost of the measuring device are also important.

Analytics with Raman spectroscopy offers the added advantage of being able to carry out absolute measurements and studies of organic and inorganic components, as well as a simple calibration process. In addition, Raman spectroscopy also makes it possible to make do with existing knowledge about the composition of the processed material. This is of great importance especially in the post-consumer field, where it is almost impossible to imagine representing all possible material combinations that occur in real life in models, which other measurement concepts require, however, as a necessary basis.

Another possibility is to use NIR spectroscopy as a physical method to study, for example, the energy spectrum of a sample, using radiation or waves: increasing demands on the quality of plastic products, as well as the need to reduce costs in production and preparation, require the use of fast and reliable inspection methods that process-relevant quality parameters would be recorded as early as possible. A method that can achieve this is fast NIR spectroscopy.

The measuring structure for NIR spectroscopy can be implemented at low cost also in industry. No sample preparation is required, and the measurement itself is performed using non-destructive methods. Measurements can be carried out on granulates, powders or finished parts.

In addition, this method can be used to quality control the polymer portion already in the PCU pre-treatment unit or in the cutting seal. This control provides, for example, information on the composition of polymer mixtures or the moisture content of plastic. This avoids batch errors and continuously documents quality attributes.

NIR technology is currently used only to a limited extent in the field of plastics, for example in sorting processes. Currently, enterprises carry out incoming and outgoing control in accordance with the established procedure. These activities are costly and time consuming. In addition to these inspections, roof fabrication and preparation are often necessary. When using Raman or NIR technology, sample preparation is preferably eliminated. Then, using the chemometric model created using NIR spectroscopy, information about the material being tested can be obtained simply and within seconds.

Examples of the proposed device

The objective of the invention is to create in-line process control in a production plant or continuous process control in extrusion plants. Material properties must be determined that can be measured in a reproducible manner with sufficient accuracy for the user.

The required properties are, for example, the following:

- humidity,

- content of additives/fillers,

- qualitative and quantitative color content,

- polymer composition, copolymer content,

- detection of cross-linking or degree of cross-linking (gelation).

These parameters must be measured and analyzed. Below are described examples of the proposed device for the preparation, processing and/or recycling of materials, in particular thermoplastic materials, from which information about these parameters can be obtained in-line by means of a physical method such as Raman or NIR spectroscopy.

Two example devices are shown in FIG. 1, 2, 3a, 3b, 4. As can be seen in Fig. 1-4, the device includes the above-described receiving hopper 1, i.e. cutting seal or Preconditioning Unit. The receiving hopper 1 contains a side wall 2 and a bottom 3 and is cylindrical. As an alternative to this, the receiving hopper 1 can also be substantially conical or have a conical or cylindrical wall section.

The receiving hopper 1 further contains a mixing and/or grinding device located near the bottom 3. In the example in FIG. 1-4, the receiving hopper 1 contains, as a mixing and/or grinding device, a mixing and/or grinding tool 4 rotating around a vertical axis 9 of rotation. It serves to move the mixture and, if necessary, also to heat, grind and/or soften the processed lump or in the form of particles of material, and during operation in the receiving hopper 1 a mixing clot is formed.

In the receiving hopper 1 the material is usually in lumps or particles, for example in the form of ground material or film scraps. Moreover, such film scraps have a thickness of about 10 microns, and here there can already be individual polymer layers in the film structure of up to several millimeters. In this case, film scraps can be imagined rather as surface formations. Both other sizes can range from a few millimeters to 30-500 mm. However, they can also be only a few millimeters. The size is determined mainly by pre-processing.

The ground materials can have dimensions of 30-50 mm. Cubes or spherical or spherical formations often appear. However, dusts or fine formations such as microgranulate or granules can also be used.

It is important that the materials behave like a fluid and are supported by the mixing and/or grinding tool 4, having a peripheral speed of 1-100 m/s, circulating in the form of a clot. The peripheral speed of the mixing or grinding tool 4 is preferably selected so that the lump or particulate material circulates radially at a speed of 0.3-45 m/s and/or in the vertical direction at a speed of 0.1-60 m/s.

In this case, the material is mainly in the zone 0-80% of the height of the receiving hopper 1. Outside on the receiving hopper 1, i.e., for example, on the side wall 2, the material has a direction of movement in the direction of the periphery and a direction of movement that is oriented preferably also up. It is important that the material is frequently and regularly replaced at the side wall 2 or at the measuring position located there.

For example, when processing films or fibers, the material in receiving hopper 1 has an average residence time of 10-15 minutes. The material circulates at a speed of approximately 15 m/s. Accordingly, a certain volume segment will pass by the measuring position on the side wall 2 40-200 times. For this reason, both long-term measurements are possible, i.e. integration during the measurement itself, as well as a large number of measurements in a very short time, i.e. then statistical methods can be used in the assessment to increase the informativeness of the measurement, as discussed in more detail below.

In fig. 1, the detail shows that in the side wall 2 of the receiving hopper 1 for unloading, for example, in the height zone of the mixing and/or grinding tool 4, there is a hole 8. Through it, pre-processed plastic is unloaded from the receiving hopper 1. If there are several in the receiving hopper 1 mixing and/or grinding tools 4, then the hole 8 can be located in the area of the lowest, closest to the bottom of the mixing and/or grinding tool 4.

A conveyor, for example an extruder 5, with a screw 6 rotating in a housing 16, for example a plasticizing or agglomerating screw, captures the pre-processed material coming out of the hole 8. In this case, the conveyor body 16, as in FIG. 1 and 2, may have on its end side or in the side wall a feed hole 80 for the material captured by the screw 6. This supply opening 80 is in communication with an opening 8 through which the material exits the receiving hopper.

The device further comprises a spectroscopic and/or spectrometric measuring device 10 for analyzing the moving lump or particulate material located inside the receiving hopper 1, or for obtaining information about the correspondingly measured material, in particular quantitative and/or qualitative characteristics of the corresponding material. This is a measuring device 10 based on the physical method described above for studying, for example, the energy spectrum of a sample using radiation or waves.

An example of such a spectroscopic and/or spectrometric measuring device 10 combined with the receiving hopper 1 is shown in FIG. 1-4. The measuring device 10 measures inline, i.e. in the current processing mode, at least part of the material moving inside the receiving hopper 1 is lumpy or in the form of particles.

The measuring device 10 exerts a physical effect, such as emitting electromagnetic radiation, sound, electrical voltages, or magnetic fields to excite at least a portion of the rotating lump or particulate material. This is caused in the illustrated example by an excitation source 11 acting or directed into the receiving hopper 1. As an option, several such excitation sources 11 can also be provided.

In the illustrated example, the excitation source 11 emits electromagnetic radiation to excite the material. The measuring signals arising as a reaction to the influence, for example, the characteristic spectra of electromagnetic radiation scattered on the measured material, are detected by the measuring device 10. For this purpose, it contains at least one detector 12 for recording the measuring signals arising as a reaction to the influence, in particular the characteristic spectra of the scattered on the measured material. material of electromagnetic radiation. In the example in FIG. 1-4 the detector 12 is talking about a spectroscope.

In fig. 1, 2 show the structural connection of the Raman spectrometer as a measuring device 10 with the receiving hopper 1 or the pre-processing unit PCU. In this case, a Raman probe is attached to the side of the receiving hopper 1 as a measuring head 24 with a lens system 22 at a height below the usual level of material or the filling level of particles moving in the receiving hopper 1. As can be seen in FIG. 1, 2, the measuring head 24 combines a light output for the light emitted by the excitation source 11 and a detection input of the detector 12 for scattered light from the receiving hopper 1.

However, the path of the beam emitted by the excitation source 11 towards the interior of the receiving hopper 1 and the path of the scattered light beam from the receiving hopper 1 towards the detector 12 can also be realized separately from each other. It is also possible for the detector 12 to be integrated into the measuring head 24. In this case, the measuring head 24 can be cooled.

As an alternative for spectroscopic and/or spectrometric analysis of the material in the receiving hopper 1, the measuring device 10 may also comprise a detector 12 for atomic or molecular spectroscopy, in particular a device for Raman, NIR, UV/Vis, fluorescence and/or absorption spectroscopy.

In the example in FIG. 1-4, the measuring device 10 further comprises a processing and control unit 40, which is in data exchange with the measuring device 10, specifically with the excitation source 11 and the detector 12. The unit 40 controls, on the one hand, the measuring device 10 for physical action, in particular for emission of electromagnetic radiation. On the other hand, the unit 40 controls the measuring device 10 in order to detect the resulting measuring signals, in particular the characteristic spectra of scattered electromagnetic radiation, and make available the measured values thus obtained.

As shown schematically and in detail in FIG. 1, 2, the excitation source 11, the detector 12 and the processing and control unit 40 are linked to the receiving hopper 1 without vibrations through fiber optic systems and/or light guides 14. Alternatively, the excitation source 11, the detector 12 and the processing and control unit 40 can also be located physically distant from the receiving hopper 1 or, for example, by means of holding devices on it.

If, for example, a laser is used as the excitation source 11, then it is preferable, as in the example in FIG. 1, 2, disconnect the detector 12 from the receiving hopper 1 via fiber optics. If fiber optics are not to be used for the laser or excitation source 11 and detector 12 (free-beam system), then vibration-free sensor coupling must be achieved by positioning at a distance.

When using fiber optics, it is easier to decouple the processing and control unit 40 and sensors or detector 12 from the receiving hopper 1, which is subject to temperature fluctuations, vibrations, etc. In this example, the fiber optics are chosen such that they have a length of less than 100 m, for example less than 30-50 m, preferably less than 15 m, in order to minimize the corresponding signal attenuation, which advantageously also leads to cost savings, since Less laser power is required and the signal-to-noise ratio is improved.

Optical elements and imaging systems are protected from environmental influences such as dust, moisture, temperature, sublimates, etc., preferably by suitable measures such as air blowing, dry air, NO ₂ blowing, etc.

In the receiving hopper 1 there is at least a single-measurement opening 20 through which the materials inside the receiving hopper 1 are measured. As can be seen in detail in FIG. 1, 2, it is located in the side wall 2 of the receiving hopper 1. Through the measuring hole 20, a physical effect transmitted by the excitation source 11, in this example, emitted electromagnetic radiation, acts on the material inside the receiving hopper 1.

The measuring hole 20 can have a diameter of 0.5-100 mm and is closed by a window 21 made of a material permeable to physical influence, such as electromagnetic radiation, such as sapphire glass. Such a window 21 causes an effective separation between the sensory elements, i.e. measuring device 10, and the material being measured.

In the example in FIG. 1-4, the measuring hole 20 is located in the side wall 2 of the receiving hopper 1 in the area of the lower third of its height. As an alternative to this, the measuring hole 20 can also be located in the height zone of the lowest mixing and/or grinding tool 4 closest to the bottom, in particular slightly above or below it, preferably outside the shortest distance between the extreme point of the mixing and/or grinding tool 4 and side wall 2.

The preferred mounting position of the measuring device 10 is on the side of the receiving hopper 1, because in this position the shortest distances to the measured material can be realized. The distance between the exciting system, i.e. an excitation source 11, for example a laser or a NIR radiation source, and a measuring system, i.e. detector 12, and the material being measured should preferably be as small as possible. Thus, it is preferable, on the one hand, the excitation source 11, i.e. light sources can be kept small in size, while at the same time providing a good measuring signal, because the light intensity decreases with 1/r ² , where r is the distance between the detector 12 and the material being measured.

When mounting sideways on the receiving hopper 1, the position in which the density of the material and the pressure on the side wall 2 is greatest is preferably selected.

Below is described an example of a method for preparing, processing and/or recycling materials, in particular thermoplastic materials, using a hopper located on the receiving hopper 1, i.e. cutting seal or PCU, measuring device 10, such as a Raman spectrometer.

The measured material must pass by the sensors of the measuring device 10 with sufficient frequency, and the material must pass the focal point 23 of the excitation source 11. A lens or lens system 22 is provided to focus the electromagnetic radiation of the excitation source 11 onto a focal point 23. The focal point 23 lies on or directly behind the window 21, preferably at a distance of a maximum of 10 cm behind it. The higher at this focus point 23 the clamping pressure that the rotating material exerts on the receiving hopper 1 or on its side wall 2, especially for materials with low bulk density, the higher the intensity of the measuring signal, because the material lies at focus point 23.

If the focus point 23 lay further back, i.e. further inside the receiving hopper 1 or in the material, then scattering effects and reduced intensity would negatively affect the signal and accordingly reduce the signal-to-noise ratio. For this reason, side mounting in the receiving hopper 1 is preferable, preferably in its lower part, as described above.

Preferably, the method is carried out in the receiving hopper 1 so that the level of the material particles or the resulting mixing clot in the receiving hopper 1 is maintained so that it always lies above the excitation source 11 or the light source.

Thus, in the proposed device, the material always covers the window 21 under production conditions. This coating also serves to shield extraneous light in the frequency range 50-1008 nm, in particular 785 ± 215 nm, in which the measuring frequencies lie. In this case, we are talking about 785+215 nm for the Stokes range, and 785-215 nm for the anti-Stokes range (Fig. 5). The Raman effect involves both energy transfer from a photon (Stokes scattering) to a molecule and from a molecule to a photon (anti-Stokes scattering). Both transfers can be assessed separately and/or in relation to each other. Furthermore, with the preferably always covered measuring head 24/window 21, good stability of the measuring signal is preferably achieved during the measuring time. A range of ± 245 mm is also available as an option (Fig. 6).

As mentioned above, the window in the example in FIG. 1-4 is preferably made of sapphire glass to ensure the passage of relevant frequency spectra in the range 570-1008 nm, in particular 785 ± 215 nm. To cover applications in the 785 nm wavelength range, at least the range between 931 nm (Stokes) and 678 nm (anti-Stokes) must be passed.

In this example, the surfaces of the window 221 are smooth and oriented parallel to each other. As an option, the inner surface of the window 21 facing the receiving hopper 1 is made concave in accordance with the radius of the receiving hopper 1, and the outer surface of the window 21 facing away from it is concave parallel to the inner surface.

As already mentioned above, the excitation source 11 can be in this example a laser with a wavelength range of 100-1400 nm, and in the region of infrared, visible and/or UV light, for example with a wavelength range of 780±250 nm. Other possible lasers used may cover the wavelength range 532±215 nm, 638±215 nm, 820±215 nm and/or 1064±215 nm.

The laser power lies, for example, in the range 15 mW - 5 W, with the range 100-500 mW being preferred. The use of lasers with high energy density is preferably possible because the material is constantly replaced and due to this there is no change in the measured material. A special need for high energy density may be required, for example, in the case of very dark colored polymers.

Next, you should pay attention to the ratio of laser power to integration time. It lies preferably in the range 5-5000 mW/s, in particular 15-1000 mW/s.

It is recommended to cool the measuring head 24 of the measuring device 10 with the lens system 22, located on the measuring hole 20 or on the window 21, so that the temperature remains below 90°C for a long time, preferably below 60°C. In this case, gases or liquids can be used as a cooling medium, but a Peltier element can also be used.

When using NIR, the conditions described above also preferably apply. In this case, the window may, however, consist of quartz glass, so that the relevant frequency spectra in the range 760-2500 nm for NIR are transmitted.

When simultaneously mounting Raman or NIR spectroscopy-based measurement devices 10, fiber optic systems should be preferred to keep installation simple. Fiber optic systems require a minimum of 21 spaces directly in front of the window. In this case, it is possible to connect both measuring devices 10 through one window 21, as well as through different windows 21. It has proven expedient if the windows 21 are located at substantially the same height in the peripheral direction. Local proximity should be sought, but is not necessary.

The range of volume of material that can be examined is determined by the cross-sectional area of the measuring spot of 0.1-5 mm, in particular 1-3 mm, and the depth of penetration into the material of 0.3-30 μm, in particular 8-15 μm. The penetration depth, which in practice leads to good measured values, lies in the range of 8-15 µm. The cross-sectional area of the measuring spot in this example is 1-3 mm, so that a volume of about 0.00015 mm ³ can be examined. For this reason, the measurement frequency or frequent passage of the measured material past the window 21 in order to achieve representative measurement results.

Due to the fact that the material in front of the window 21 or at the focus point 23 is frequently and regularly replaced during operation, and due to the agreed frequency of measurements or due to the corresponding measurement duration, extremely high accuracy is achieved.

The processing and control unit 40 outputs, on the basis of the obtained measured data, information about the respective measured material, in particular the quantitative and/or qualitative parameters of the corresponding material, and makes it available. For example, unit 40 can spectrometrically and/or spectroscopically analyze the measuring signals that arise as a reaction to the influence, in particular the characteristic spectra of electromagnetic radiation scattered on the measured material.

Implementation of the method and evaluation

As has already been said, the inline lumpy or particulate material moving inside the receiving hopper 1 is analyzed or measured spectroscopically and/or spectrometrically, and the measured values thus obtained are used to obtain information about the respective measured material, in particular the quantitative and/or qualitative parameters of the respective material . In this example, the measurement signals generated in response to electromagnetic radiation are preferably detected spectrometrically and evaluated in the form of characteristic spectra of electromagnetic radiation scattered on the measured material.

The evaluation of the measurement results or spectra obtained in this way is carried out by the processing and control unit 40 and preferably occurs as follows.

Due to the frequent passage of material particles in a state ranging from hard to partially softened past the measuring position or focal point 23, long measuring times can be used, which allows the use, for example, of low-power lasers of 20-200 mW, while the information content of the measurement results remains quite accurate.

The processing and control unit 40 in this case controls the measuring device 10 or the excitation source 11 in such a way that it continuously transmits a physical effect, for example electromagnetic radiation generated by a laser, for a predetermined period of time, for example from less than one second to several seconds or one minute or more. The processing and control unit 40 then calculates for the corresponding time interval individual general information about the correspondingly measured material, i.e. all particles of material that during this period of time passed by the measuring hole 20 or window 21 and were recorded by detector 12. For example, it is possible to compile a separate total spectrum for all these particles of material.

As an alternative to this, the processing and control unit 40 can control the measuring device 10 or the excitation source 11 in such a way that it repeatedly transmits a physical effect, for example electromagnetic radiation emitted by a laser, at predetermined multiple times. Thus, with each impact, the corresponding one particle of the material rotating in the receiving hopper 1 is excited and scatters the radiation detected by the detector 12. The processing and control unit 40 can then calculate the average value of the information about the correspondingly measured material based on selected or all measured values detected at these moments of time by the measuring device 10, in particular the detector 12, for individual particles, and make available. This means that the average value is formed from a large number of spectra of individual particles.

If high/increased laser powers are required due to the materials being measured, then passing the measured material past the focal point 23 prevents the high laser energy density from affecting the material being measured. The methodically unknown material is excited at a higher energy density, and the processing and control unit 40 optionally reduces the laser power until the detector 12 is in its linear range. In a static measuring process, this automatic measuring process could not be applied, because the sample or material would burn or melt.

Since in the receiving bin there is 1, i.e. in the cutting compactor or pre-processing unit, there is usually a change in the temperature of the processed material, the proposed device may, if necessary, also contain a temperature measuring device 30, in front of the processing and control unit 40.

In the normal operating mode of the receiving hopper 1, in any case, a change in the temperature of the material occurs: the material at room temperature is fed or loaded from above into the receiving hopper 1, and then heated, for example, due to the movement of the mixing and/or grinding tools 4 or due to friction. The material becomes hot and softens, but still remains in the form of particles or lumps and does not melt.

However, this change in temperature leads to a change in the spectra recorded by the measuring device 10 or detector 12 due to the structural change of the polymers at this stage of the process. It is therefore preferable if appropriate adjustments are made in the evaluation, especially when the correspondingly recorded spectrum must be matched to existing spectrum databases.

This optional temperature measuring device 30 measures the temperature inside the receiving hopper 1 and/or the temperature of the material and transmits it to the processing and control unit 40. In this case, for example, using a temperature probe inserted into the edge layer of the material, the temperature of the material is recorded and used as a set value for correcting the spectra. Alternatively, the temperature of the receiving hopper 1 can also be used as a value. An additional thermal measuring device, for example an optical one, can also be placed on the receiving hopper 1 to record the temperature. In this regard, it is particularly preferable to install the temperature measuring device 30 in local proximity to the window 21 closing the measuring opening 20 or the measuring head 24 of the measuring device 10. The temperature measuring device 30 can be located in the receiving hopper 1, for example, at the same height, in particular in the same position as at least one measuring hole 20.

The processing and control unit 40 uses the measured values obtained by the temperature measuring device 30 to correct the influence of temperature on the information obtained for the correspondingly measured material, in particular the temperature-dependent characteristic spectra of electromagnetic radiation scattered on the measured material, and makes available the thus corrected information, in particular the spectra .

The information obtained in this way is included in the assessment and serves as an indication of the temperature adjustment of the spectra. For example, the temperature of the material in the receiving hopper 1 is measured and transmitted to the processing and control unit 40. There, the measured actual temperature is used to correct the spectra, for example to a reference temperature, to allow easy comparison with stored reference spectra. For example, the temperature-induced shift of spectra to higher intensities is corrected.

For particularly simple evaluation of information obtained for measured material, such as spectra, the processing and control unit 40 may include a memory in which reference information, such as quantitative and/or qualitative reference parameters or reference spectra, is stored. The processing and control unit 40 can then compare the information obtained for the correspondingly measured material, such as spectra, with reference information, such as reference spectra, and determine the deviation from the reference information or reference spectra. This resulting deviation can then be sent, for example, to a process control unit and/or a display unit.

The processing and control unit 40 can optionally also interact or exchange data with the process control unit 50. Such a process control unit can, for example, use data transmitted by the processing and control unit 40, i.e. information about the correspondingly measured material, such as quantitative and/or qualitative parameters of the corresponding material, for monitoring and/or managing the process in the receiving hopper 1 and/or the subsequent process chain.

Such a process control unit 50 can, for example, based on the data transmitted by the processing and control unit 40, carry out

- dosing of fillers into receiving hopper 1 and/or

- supply of materials, such as polymers, fillers, etc., into the receiving hopper 1 and/or into the unloading device connected to it and/or

- unload processed materials, in particular granules, from the receiving hopper 1 by means of an unloading device connected to it, such as a conveyor. This is discussed in more detail below.

Application examples

Example 1

Below, a first example of the application of the method and apparatus for the preparation, processing and/or recycling of materials, in particular thermoplastic materials, is described.

In the production of hygiene products, such as diapers, bandages, etc., various polymers with different viscosities and degrees of filling with fillers, for example CaCO ₃ , are used. At the same time, the share of nonwoven material in hygiene products consists mostly of unfilled PP, and the film is filled with CaCO ₃ HDPE. The die-cut and film residues generated during production therefore contain different proportions of polymer and different degrees of filling.

In order to obtain a material of constant quality from these starting materials, the quantities of the different filler and/or polymer components must be known. During the compounding stage, the addition of polymer, additives and filler can establish a specific mixture for the final product if the incoming components are absolutely known. This results in a corresponding increase in flexibility. Measurement before and for control after the compounding step controls the proportions of the supplied components, thereby guaranteeing certain properties and minimizing production costs.

Experimental design

When carrying out this experiment, an INTAREMA 1108TVEplus machine containing a measuring device 10 with a detector 12 for Raman spectroscopy and a receiving hopper 1, i.e. cutting compactor or pre-treatment unit was loaded with waste from the production of sanitary film. This material has the form of lumpy film pieces. Table 1 summarizes the experimental data.

Table 1. Experienced data of application example

Material Car PCU temperature PCU power Tool rotation speed Laser power Integration time Number of measurements Measurement time per spectrum °C kW rpm mW With With LPDE+
_CaCO3 INTEREMA 1108
TVEplus 102 36-38 750 200 3 10 thirty

Grade

Unexpectedly, despite the already mentioned high speeds of rotation of particles in the receiving hopper 1, it was possible to register clear spectra with detector 12 or a spectroscope. The spectra recorded by detector 12 are shown in FIG. 7. The spectra show mixtures of PE and CaCO ₃ with varying percentages (1%, 2%, 5%, 10%, 15%, 17.5%, 20%).

The recorded spectra are evaluated by the processing and control unit 40 for the proportion of CaCO ₃ , and information about the proportion of CaCO ₃ , as a percentage of the total material, becomes available.

Interpretation

In the measurement results, one can detect a change in the proportion of CaCO ₃ in the input material over a process duration of about 4 hours (Fig. 8). In this way, it is possible to output a control signal to a process control unit 50 connected to the processing and control unit 40, for example a dispenser, on the basis of which the supply of CaCO ₃ in the form of powder or masterbatch is adapted accordingly. In the case of a larger proportion in the input material, the dosed quantity can therefore be reduced, and in the case of a smaller proportion in the input material, it can be increased. In the resulting final product the proportion of CaCO ₃ is then preferably uniform. Typically, for injection molded products, the proportion of CaCO ₃ is 15-25%, depending on the application, and the deviation should therefore only be ± 1%.

Example 2

A second example of the method and device is described below.

When reusing used packaging materials from the food/non-food industry, sorting and washing processes separate and clean the different polymer streams as best as possible. In the subsequent process of thermal deformation (extrusion), homogenization and filtration of the melt are carried out. The resulting reclaims, depending on the application, must meet a certain quality: for example, for the production of blown film from HDPE, the proportion of PP should not exceed a certain percentage, because Then, under certain circumstances, the desired mechanical properties are subsequently not achieved or weldability is no longer ensured. Since 100% purity of the grade can never be achieved in the preceding sorting process, it is advisable, for example, to produce granules from the extruder 5 connected to the receiving hopper 1 with a higher proportion of PP. Thanks to the built-in Raman measurement, it is possible to more easily determine the proportion of PP in the receiving hopper 1 and control the release of finished granules if the proportion of PP is too high.

Experimental design

When conducting the experiment, an INTAREMA 80TVEplus machine was used, containing a measuring device 10 with a detector 12 for Raman spectroscopy and a receiving hopper 1, i.e. cutting compactor or pre-treatment unit. In this experiment, by adding PE film to pure PP film in the receiving hopper 1, the suitability of the Raman spectroscopy-based measuring device, which repeats measurements at specified times, was confirmed. For this purpose, two rolls of film, namely PP film and HDPE film, of known width and thickness were fed to the receiving hopper 1 through separate feeding devices. The percentage separation was determined by calculation based on the surface density and was confirmed by selective control of the resulting granulate.

Table 2. Experience data from the second application example

Material Car PCU temperature PCU power Tool rotation speed Laser power Integration time Number of measurements Measurement time per spectrum °C kW rpm mW With With PE/PP INTEREMA 1108
TVEplus 100 40-41 750 150 4 10 40

Grade

The spectra recorded by detector 12 are shown in FIG. 9. Spectra indicate mixtures of PP and PE with percentages varying accordingly (100%, 90%, 70%, 50%, 25%, 10%, 0% PP).

The recorded spectra are evaluated by the processing and control unit 40, and the portion of PP is made available to them as a percentage of the total material (Fig. 10).

Interpretation

By using this measurement process, the proportion of PP in a material flow can be measured with an accuracy of less than 1%. Thus, the proportion of PP in the final product can be controlled by adding PE. This is especially preferable because It is known from practice that already a PP share of about 5% in the HDPE flow reduces weldability so that the production of bags is no longer ensured.

Example 3

A third example of the method and device is described below.

PE/PP composites are used as packaging films for food products. In this case, we are talking about a multilayer structure, in the middle of which there is a PA film, for example, to preserve the aroma. PE and PA are polymers that do not mix well. However, by adding compatibilizers, it is possible to obtain a very good material for film or injection molding. Since compensators are very expensive and the proportions of PA and PE fluctuate, preparation costs can be saved and the final product can be optimized if the polymer fraction can be accurately determined and the addition of compatibilizer controlled accordingly. The residues mostly have a PA proportion of about 40% and a PE proportion of 60% and are in the form of surface formations, edge strips and film rolls.

Experimental design

When conducting the experiment, an INTAREMA 1108 TE machine was used, containing a measuring device 10 with a detector 12 for Raman spectroscopy and a receiving hopper 1, i.e. cutting seal or Preconditioning Unit. In this experiment, by adding PE/PA edge strips and film pieces into the receiving hopper 1, the suitability of the continuous measuring device 10 based on Raman spectroscopy was confirmed. In the resulting granulate, the corresponding polymer proportions were measured using laboratory measuring instruments to control the pre-inline determined proportions. Table 3 summarizes the experimental data.

Table 3. Experience data from the third application example

Material Car PCU temperature PCU power Tool rotation speed Laser power Integration time Number of measurements Measurement time per spectrum °C kW rpm mW With With PE/PA INTRAEMA 1108 TE 107 48-54 750 350 3 10 thirty

Grade

The recorded spectra are evaluated by the processing and control unit 40, and the proportion of PA to PE is displayed by it (Fig. 11).

Interpretation

There are corresponding shifts due to different versions of recycled films. For example, until about 9:55 the proportion of PE increases. However, this is not advisable in order to achieve the desired final quality of the final product, because too small a proportion of PA negatively affects the properties of the final product, and, in addition, too much of the compound is dosed. For this reason, in response to the information received about the measured material, it is possible to connect a branch at the end of the preparation plant and discharge the resulting granulate in the range from 9:55 to 10:08.

The device and method described above thus provide, when using spectroscopic and/or spectrometric measuring devices 10, efficient in-line analysis, monitoring and, if necessary, process control in systems for the preparation, processing and/or recycling of materials, in particular thermoplastic materials, with receiving hopper 1, i.e. cutting compactor or PCU pre-treatment unit.

In addition, the information/data transmitted by the evaluation unit can also be used in the subsequent production chain, for example when dosing fillers, releasing finished granulate, as well as when feeding other polymers, for example into the receiving hopper 1, i.e. cutting compactor or PCU pre-treatment unit.

Claims (78)

1. A method for preparing thermoplastic materials for reuse, characterized in that - the thermoplastic material is moved and mixed, and also crushed and softened in a receiving hopper (1), made in the form of a cutting compactor or a pre-processing unit (PCU), while the material remains in the receiving hopper (1) in lumps or particles and unmelted, And - carry out built-in measurements, spectroscopic and/or spectrometric measurements of lumpy or particulate material moving in the receiving hopper (1), and the measured values thus obtained are used to obtain information about the quantitative and/or qualitative parameters of said material, wherein at least parts of the lumpy or particle-shaped material located inside the receiving hopper (1) and rotating there are excited by the action of electromagnetic radiation and the spectra of electromagnetic radiation scattered on the measured material, arising as a response to said action, are detected, for excitation, light is used in the region of infrared, visible and/or UV light in the range of 100-1400 nm and/or for excitation a laser is used in the wavelength range of 100-1400 nm, wherein the light is detected and analyzed in order to determine, during the technological process in an on-line mode, the quantitative and/or qualitative parameters of the specified material or changes in these parameters during the process and use them to monitor and/or control the process and/or use these parameters for control of the process in the receiving hopper (1), wherein the electromagnetic radiation exciting the material is focused to a focal point (23), which lies inside the receiving hopper (1) on the hopper wall or directly behind the hopper wall or at a distance of maximum 10 cm behind the hopper wall, in this case, electromagnetic radiation excites a volume determined by the cross-sectional area of the measuring spot in the range of 0.1-5 mm and with a penetration depth into the material of 0.3-30 μm, Moreover, in the outer zone of the receiving hopper (1) or on the side wall (2) of the receiving hopper (1), the lumpy or particulate material has a circular direction of movement and/or a direction of movement directed predominantly upward, the lump or particulate material is rotated circumferentially at a speed of 0.3-45 m/s and/or in the vertical direction at a speed of 0.1-60 m/s, so that the lump or particulate material is replaced frequently and regularly in the external area of the receiving hopper (1) or on its side wall (2). 2. Method according to claim 1, characterized in that the thermoplastic material is also heated in the receiving hopper (1). 3. The method according to claim 1, characterized in that spectroscopic and/or spectrometric measurements are carried out by Raman spectroscopy, near-infrared spectroscopy (NIR), ultraviolet/visible spectroscopy (UV/VIS), fluorescence spectroscopy and/or absorption spectroscopy. 4. Method according to any one of paragraphs. 1-3, characterized in that light in the range of 500-1000 nm is used for excitation, or a laser power in the range of 15 mW - 5 W, preferably 100-500 mW, is used for excitation. 5. Method according to any one of paragraphs. 1-4, characterized in that electromagnetic radiation excites a volume determined by the cross-sectional area of the measuring spot in the range of 1-3 mm and the depth of penetration into the material of 8-15 microns. 6. Method according to any one of paragraphs. 1-5, characterized in that electromagnetic radiation exciting the material is introduced inside the receiving hopper (1) or into the material in one or more of the following positions: - below the filling level of the receiving hopper (1) with material or particles of material during operation, - at a height and/or at a distance from the bottom (3) or from the mixing and/or grinding tool (4), at which/at which the electromagnetic radiation occurs constantly below the specified, according to the method, filling level of those located or rotating in the receiving hopper (1) particles of material, and/or below the level of the mixing clot formed during the movement and/or rotation of particles of material, - at the height of the middle third of the level of filling the receiving hopper (1) and/or mixing clot with material, specified according to the method, - in the area of the receiving hopper (1), in which the density of moving and/or rotating particles of material is greatest, and/or - in the area of the receiving hopper (1), in which moving and/or rotating particles of material exert the greatest pressure on the side wall (2) of the receiving hopper (1). 7. Method according to any one of paragraphs. 1-6, characterized in that the lumpy or particulate material or individual particles of material located inside the receiving hopper (1) and rotating there, at given times, at multiple times, are excited using electromagnetic radiation, while determining and storing an accessible average value from information about the quantitative and/or qualitative parameters of the measured material or individual particles, which is determined on the basis of selected or all measured values obtained at specified times. 8. Method according to any one of paragraphs. 1-7, characterized in that the lumpy or particle-shaped material located inside the receiving hopper (1) and rotating there is continuously excited for several seconds by electromagnetic radiation, and in the corresponding period of time based on the measured values continuously obtained within this period of time calculate and make available a quantitative and/or qualitative parameter of the material. 9. Method according to any one of paragraphs. 1-8, characterized in that they measure the temperature inside the receiving hopper (1) and/or the temperature of the material and include in the assessment information about the temperature, which serves as an indicator for information about the quantitative and/or qualitative parameters of the corresponding material, and/or record the temperature of the material and use it as a characteristic for adjusting the spectra. 10. Method according to any one of paragraphs. 1-9, characterized in that quantitative and/or qualitative reference parameters or reference spectra are stored, and the quantitative and/or qualitative parameters or spectra obtained for the corresponding measured material are compared with quantitative and/or qualitative reference parameters or reference spectra, the deviation from quantitative and/or qualitative reference parameters or reference spectra and the resulting deviations are displayed and/or used to monitor and/or control the process in the receiving hopper (1) and/or the subsequent technological chain. 11. A device for implementing a method for preparing thermoplastic materials for reuse according to any one of claims. 1-10 containing at least one receiving hopper (1) for thermoplastic material, which is a cutting compactor or pre-processing unit (PCU), with a mixing and grinding device for said material, a spectroscopic and/or spectrometric measuring device (10) for analyzing the lumpy or particulate material moving inside the receiving hopper (1), processing and control unit (40) connected to the measuring device (10) with the ability to exchange data, and process control unit (50), in this case, the measuring device (10) contains: - at least one excitation source (11), operating or directed into the receiving hopper (1), designed to emit electromagnetic radiation on the material inside the receiving hopper (1), and - at least one detector (12) for recording spectra of electromagnetic radiation scattered on the material being measured, wherein the excitation source (11) is configured to emit light in the region of infrared (IR) light, visible and/or UV light, or the excitation source (11) is a laser, wherein the receiving hopper (1) contains a side wall (2) and a bottom (3) and is made essentially conical or cylindrical, or has a conical or cylindrical section of the side wall, in the receiving hopper (1) as a mixing and grinding device there is at least one mixing and/or grinding tool (4), installed with the possibility of rotation around a vertical axis (9) of rotation, when the mixing and grinding device is operating in the receiving hopper (1 ) a vortex and/or a mixing clot is formed from the processed material, lump or in the form of particles, in the side wall (2) of the receiving hopper (1) there is at least one measuring hole (20), and the measuring hole (20) is made so that the electromagnetic radiation emitted by the excitation source (11) affects the material in the receiving hopper (1 ) and scattered light from the receiving hopper (1) was detected, wherein said at least one measuring hole (20) is located in the side wall (2): - in the height zone of the lowest mixing and/or grinding tool (4), closest to the bottom, and/or - in the area of the lower third of the height of the receiving hopper (1), wherein the processing and control unit (40) is configured to: controlling the measuring device (10) for transmitting electromagnetic radiation, detecting the resulting measuring signals and keeping available the measured values of the electromagnetic radiation spectra obtained in this way; with the ability to display and store information about the quantitative and/or qualitative parameters of the material based on the measured values of the spectra of electromagnetic radiation; And with the ability to interact with the process control block (50) and with the ability to exchange data, Moreover, the process control unit (50) is configured to use the quantitative and/or qualitative parameters of the material transmitted by the processing and control unit (40) to control and/or control the process in the receiving hopper (1) and/or the subsequent technological chain. 12. The device according to claim 11, characterized in that the receiving hopper (1) is designed to heat the material being processed. 13. The device according to claim 11, characterized in that the peripheral speed of the mixing and/or grinding tool (4) is selected with the possibility of rotating lump or particle-shaped material around the circumference at a speed of 0.3-45 m/s and/or in the vertical direction - at a speed of 0.1-60 m/s. 14. Device according to any one of paragraphs. 11-13, characterized in that in the receiving hopper (1), in its side wall (2), in the height zone of the lowest mixing and/or grinding tool (4) closest to the bottom, there is a hole (8) with the possibility of unloading through it from the receiving hopper (1) of pre-processed material, with at least one conveyor made in the form of an extruder (5), with at least one plasticizing or agglomerating screw (6) installed in the housing (16) with the possibility of rotation, installed to receive pre-processed material coming out of the hole (8), and the housing (16) has a feed hole (80) on the end side or in the side wall for the material captured by the screw (6), and the feed hole (80) communicates with the hole ( 8). 15. Device according to any one of paragraphs. 11-14, characterized in that the excitation source (11), and/or detector (12), and/or processing and control unit (40) are physically spaced from the receiving hopper (1) or connected to it without vibration through fiber-optic systems and/or light guides (14). 16. Device according to any one of paragraphs. 11-15, characterized in that the measuring device (10) contains a detector (12) for Raman spectroscopy, NIR spectroscopy, UV/Vis spectroscopy, fluorescence and/or absorption spectroscopy. 17. Device according to any one of paragraphs. 11-16, characterized in that the excitation source (11) is configured to emit light in the region of infrared (IR) light, visible and/or UV light in the range of 100-1400 nm, preferably 500-1050 nm. 18. Device according to any one of paragraphs. 11-17, characterized in that the excitation source (11) is a laser with a wavelength range of 100-1400 nm and/or a power in the range of 15 mW - 5 W, preferably 100-500 mW. 19. The device according to claim 18, characterized in that the measuring hole (20) has a diameter of 0.5-100 mm, the measuring hole (20) is closed by a window (21) made of sapphire glass, transparent to electromagnetic radiation. 20. Device according to claim 19, characterized in that the window (21) has a thickness of 1-100 mm. 21. The device according to any one of paragraphs. 19 or 20, characterized in that the surfaces of the window (21) are flat and oriented parallel to each other, or the inner surface of the window (21) facing the receiving hopper (1) is made concave in accordance with the radius of the receiving hopper (1), and facing away from the receiving hopper (1) the outer surface of the window (21) is made concave, parallel to the inner surface. 22. The device according to claim 11, characterized in that at least one measuring hole (20) in the side wall (2) of the receiving hopper (1) is located: - above or below the height of the lowest mixing and/or grinding tool (4), closest to the bottom, preferably at the shortest distance between the extreme point of the mixing and/or grinding tool (4) and the side wall (2). 23. The device according to claim 11, characterized in that at least one measuring hole (20), in the side wall (2) of the receiving hopper (1), is located in one or more of the following positions: - below the filling level of the receiving hopper (1) with material or material particles during operation, - at a height and/or at a distance from the bottom (3) or from the mixing and/or grinding tool (4), at which/at which the emitted electromagnetic radiation is constantly below the level of filling specified, according to the method, with particles of material located or rotating in the receiving hopper (1), and/or the level of the mixing clot formed during the movement and/or rotation of material particles, - at the height of the middle third of the level of filling the receiving hopper (1) and/or mixing clot with material, specified according to the method, - in the area of the receiving hopper (1), in which the density of moving and/or rotating particles of material is greatest, and - in the area of the receiving hopper (1), in which moving and/or rotating particles of material exert the greatest pressure on the side wall (2) of the receiving hopper (1). 24. The device according to any one of paragraphs. 11-23, characterized in that the volume excited by electromagnetic radiation is determined by the cross-sectional area of the measuring spot in the range of 0.1-5 mm, preferably 1-3 mm, and the depth of penetration into the material in the range of 0.3-30 μm, preferably 8 -15 microns. 25. The device according to any one of paragraphs. 11-24, characterized in that it contains a lens or lens system (22) for focusing electromagnetic radiation from the excitation source (11) to a focus point (23), wherein the focus point (23) is formed on the window (21), or directly behind the window ( 21), or at a maximum distance of 10 cm behind the window (21). 26. The device according to any one of paragraphs. 11-25, characterized in that the process control block (50) is configured to, based on the data transmitted by the processing and control block (40), implement - dosing fillers into the receiving hopper (1), and/or - supplying polymers to the receiving hopper (1) and/or to the unloading device connected to the receiving hopper (1), and/or - unloading granules from the receiving hopper (1) using an unloading device connected to the receiving hopper (1). 27. The device according to any one of paragraphs. 11-26, characterized in that it contains at least one temperature measuring device (30) in front of the processing and control unit (40), wherein the temperature measuring device (30) is configured to measure the temperature inside the receiving hopper (1) and/or temperature of the material and its transmission to the processing and control unit (40), and wherein the processing and control unit (40) is configured to use temperature values measured by at least one temperature measuring device (30) to correct the influence of temperature on information about the quantitative and/or qualitative parameters of the corresponding material, or the spectra of electromagnetic radiation scattered on measured material, and storing thus corrected information on quantitative and/or qualitative parameters or spectra suitable for use. 28. Device according to claim 27, characterized in that the temperature measuring device (30) is located in the receiving hopper (1) at the same height or in the same position as at least one measuring hole (20). 29. The device according to any one of paragraphs. 11-28, characterized in that the processing and control unit (40) is configured to - controlling the source (11) of excitation of the measuring device (10), at specified times, at multiple times, to repeatedly emit electromagnetic radiation, and - calculating and storing available the average value of the quantitative and/or qualitative parameters of the corresponding material, which are obtained on the basis of selected or all measured values obtained at these points in time by the measuring device (10). 30. The device according to any one of paragraphs. 11-29, characterized in that the processing and control unit (40) is configured to - controlling the excitation source (11) of the measuring device (10) so that it continuously emits electromagnetic radiation for several seconds, and - calculating and storing available, for a corresponding period of time, information about quantitative and/or qualitative parameters, based on the measured values, continuously determined by the measuring device (10), during this period of time. 31. The device according to any one of paragraphs. 11-30, characterized in that the processing and control unit (40) contains a memory, and quantitative and/or qualitative reference parameters or reference spectra are stored in the memory, and the processing and control unit (40) is configured to compare the obtained quantitative and /or qualitative parameters or spectra with quantitative and/or qualitative reference parameters or reference spectra, and determining deviations from quantitative and/or qualitative reference parameters or reference spectra and transmitting the obtained information to the process control unit and/or to the display unit.