WO2023174487A1

WO2023174487A1 - Method for producing a material with verifiable proportion of recycled material

Info

Publication number: WO2023174487A1
Application number: PCT/DE2023/100200
Authority: WO
Inventors: Daniel KIRCHENBAUER; Jochen MOESSLEIN
Original assignee: Polysecure Gmbh
Priority date: 2022-03-15
Filing date: 2023-03-15
Publication date: 2023-09-21

Abstract

The invention relates to a method for producing a material with a verifiable proportion of a recycled material, the method comprising the following steps: • - providing a first material, the first material consisting of a recycled material and optionally a tracer; • - identifying the tracer in the first material; • - determining a signal intensity of the identified tracer in the first material; • - setting a target signal intensity by • - adding a further amount of the identified tracer to the first material depending on the determined signal intensity if the determined signal intensity is less than the target signal intensity, or • - adding further recycled material or a mixture of further recycled material and tracer, a signal intensity of the mixture being lower than the target signal intensity if the determined signal intensity is greater than the target signal intensity, so as to obtain a second material which comprises the recycled material and the tracer and has the target signal intensity; and • - optionally, combining the second material with a third material in a defined ratio, the third material being a material that does not contain the identified tracer, so as to obtain the material with verifiable proportion of recycled material.

Description

Method for producing a material with a verifiable proportion of recycled material

Field of invention

The present invention relates to a method for producing a material with a verifiable proportion of recycled material.

Background of the invention

The reuse (recycling) of recycled materials, i.e. materials that come from old products, is essential in order to conserve raw material resources and reduce the costs of producing new products.

To recycle materials, recycled material can be processed into new products. When producing such products, it may be necessary to use a defined proportion of recycled material. Furthermore, it may be desirable to be able to determine the proportion of recycled material used in the newly manufactured product.

DE 10251 675 Ai describes a process for producing a thermoplastic product using a plastic bottle recyclate. However, the proportion of plastic bottle recyclate in the final product cannot be checked or determined afterwards without knowledge of the parameters of the manufacturing process.

Task of the invention

It is therefore the object of the present invention to provide a method for producing a material with a verifiable proportion of recycled material that overcomes disadvantages of the prior art, in particular to provide a method for producing a product that includes recycled material, wherein the proportion of recycled material is in the product can be controlled, especially after the product has been manufactured.

Disclosure of the invention

This task is solved in accordance with the subject matter of the independent claims. Preferred embodiments result from the subclaims and the following description.

The task is solved in particular by a method for producing a material with a verifiable proportion of recycled material, the method comprising the steps:

- Providing a first material, the first material consisting of a recycled material and optionally a tracer;

- identifying the tracer in the first material;

- determining a signal intensity of the identified tracer in the first material; - Setting a target signal intensity

- Adding a further amount of the identified tracer into the first material depending on the determined signal intensity, if the determined signal intensity is smaller than the target signal intensity, or

- Adding further recycled material or a mixture of further recycled material and tracer, a signal intensity of the mixture being less than the target signal intensity, if the determined signal intensity is greater than the target signal intensity, by a second Obtain material that includes the recycled material and the tracer and has the target signal intensity; and

- optionally combining the second material with a third material in a defined ratio, the third material being a material that does not contain the identified tracer, in order to obtain the material with a verifiable proportion of recycled material.

Proceedings

The method according to the invention serves to produce a material with a verifiable proportion of recycled material. The material produced by the method therefore includes a proportion of recycled material and optionally a proportion of further material, for example a new material. The proportion of recycled material in the material produced can be verified in such a way that the proportion of recycled material can be reliably determined without knowledge of the parameters of the manufacturing process, in particular without knowledge of the amounts of recycled material and optional other material used in production.

Providing a first material

Providing the first material can include suitable preparation of the first material for further processing, in particular comminuting, grinding, homogenizing, etc. of the first material.

First material

The first material consists of a recycled material and optionally a tracer. If the first material does not contain a tracer, the first material consists only of the recycled material.

For purposes of the present disclosure, a recycled material is a POST-CONSUMER MATERIAL, ie, waste material from household, commercial, industrial and institutional facilities, or POST-INDUSTRIAL MATERIAL, ie, production waste and/or production waste. It can be provided that the first material is in the form of an end product, for example in the form of a window frame or part thereof, in the form of a bottle, etc.

The recycled material can comprise a plastic, in particular in an amount of at least 50% by weight, at least 60% by weight, at least 70% by weight, at least 80% by weight, at least 90% by weight or at least 95% by weight .-%, based on the total weight of the recycled material, or made of a plastic.

The plastic can be selected from the group consisting of polyvinyl chloride, polyethylene, in particular LDPE and HDPE, polyethylene terephthalate, polystyrene, polypropylene, polyamide, ABS (acrylonitrile-butadiene-styrene copolymer) and a mixture of two or more of these.

Tracer

A tracer in the sense of the present disclosure is a marking substance, that is, for example, a substance or a material that can be used to identify, sort, etc. a marked material. The tracer according to the invention can also be suitable for determining the proportion of labeled materials in compositions consisting of several materials.

The tracer can be a luminescent substance, in particular a photoluminescent substance.

Photoluminescence is the emission of photons from direct photoexcitation of any form of matter after the absorption of photons (electromagnetic radiation). Photoluminescence can involve downshift or upconversion processes. When the energy of the emitted photons is less than the energy of the absorbed photons, photoluminescence is described as a downward shift process. Conversely, photon upconversion is an optical process in which the energy of the emitted photons is higher than the energy of the absorbed photons. Both excitation and emission can take place in UV, visible or infrared (IR) light.

In order to be applicable as a tracer, it is advantageous if photoluminescent materials exhibit various characteristics, in particular a high photoluminescence quantum yield (PLQY); efficient production properties, such as synthesis temperature < 1,300 °C, not too many process steps, desired particle sizes during production, good reproducibility of material characteristics such as PLQY, decay time and emission lines and compliance with application requirements such as stability at higher temperatures, in air or media such as water or good biocompatibility .

It may be envisaged that the tracer comprises a rare earth metal, a side earth metal ion, a transition metal, a transition metal ion or a mixture of two or more thereof. Preferably, the rare earth metal is selected from the group consisting of Y, Gd, La, Lu, Sc, Ce, Dy, Er, Eu, Ho, Nd, Pr, Sm, Tb, Tm, Yb and mixtures thereof. Preferably the transition metal is selected from the group consisting of Zn, Cu, Ni, Mn, Fe, V and mixtures thereof. Other preferred metals are In, Bi, Ba, Sr, Ca, Zn, Mg and mixtures thereof. Particularly preferred tracers can be based on YBaZn or YBaZnF.

According to one embodiment, particularly preferred tracers can have the chemical formula i:

M ₂ (iyz)Yb2yRem2zAD0 _5-x Hal2x (Chemical Formula 1), where M is at least one element selected from Y, Gd, La, Lu, In, Sc, Bi and mixtures thereof; A is at least one element selected from Ba, Sr, Ca and mixtures thereof; D is at least one element selected from Zn, Mg, Cu, Ni, Mn, Fe and mixtures thereof; Hal is at least one element selected from F, Cl, Br, I and mixtures thereof; Rem is at least one rare earth element selected from Ce, Dy, Er, Eu, Ho, Nd, Pr, Sm, Tb, Tm and mixtures thereof; x is from 0.02 to 2.5; y is from o to 1; z is from o to l; at least one of y and z is at least 0.001, the total of y + z is at most 1.

Preferred embodiments of chemical formula 1 and their production are described in EP 3 431570 Bi.

Other preferred tracers are oxysulfides doped with rare earth elements.

According to one embodiment, these tracers may have the chemical formula 2:

M _2-x Rem _x 02S (Chemical Formula 2) where M can be at least one element selected from Y, Gd, La and mixtures thereof, Rem is at least one rare earth element.

Preferred tracers may be based on yttrium oxysulfide (YOS) or gadolinium oxysulfide (GOS).

Particularly preferred tracers can be based on yttrium oxysulfide (YOS), gadolinium oxide or gadolinium oxysulfide (GOS), each doped with ytterbium and erbium or doped with ytterbium and holmium.

According to a further embodiment, particularly preferred tracers can have the chemical formula 3:

Wei(a)We2(b)Ta(c)Doi(d)Do2(e)Hal(w)O(x)Te(y)Se(z) (Chemical Formula 3) where Wei and We2 are different and independent of each other are selected from the group consisting of niobium, aluminum, barium, gadolinium, lanthanum, yttrium, cerium and titanium; D01 and D02 are different and are independently selected from the group of rare earth elements; Hal is fluoride, chloride, bromide or iodide; the indices (a)-(z) are each independently o to 3, although at least one of (a) and (b) is greater than o, at least one of (d) and (e) is greater than o and at least one of (w), (x), (y) and (z) is greater than o; where the sum of (a) + (b) + (c) = i-2, preferably 1 or 2, and the sum of (w) + (x) + (y) + (z) = 2 or 3, optional with the proviso that (c) > o.

It can preferably be provided that Wei = Ce, D01 = Er and (b) = (e) = (w) = (y) = (z) = o, where (x) > o.

It can preferably be provided that the rare earth element is selected from erbium, ytterbium, thulium and holmium, preferably a combination of two rare earth oxides, preferably erbium oxide and ytterbium oxide.

Preferred embodiments and their production are described in EP3375840B1.

The tracer can be an RFA tracer. An XRF tracer is a tracer that can be detected using X-ray fluorescence analysis (XRF). The XRF tracer can be formed, for example, by defined amounts of one or more chemical elements.

Identify the tracer in the first material

In particular if the tracer is a luminescent tracer, in order to determine the identity of the tracer, i.e. to identify it, the luminescence behavior of the tracer can be analyzed with regard to a wide variety of properties.

In particular, it can be provided that the tracer is identified in the first material

- measuring an emission spectrum of the tracer;

- determining the presence and/or absence of an emission wavelength specific to the tracer;

- measuring the luminescence emission behavior of the tracer over time;

- measuring an emission intensity for one or more emission wavelengths of the tracer;

- determining an intensity ratio between emission wavelengths of the tracer; or includes two or more thereof.

Instead of analyzing defined emission wavelengths, wavelength ranges can also be analyzed.

Measuring the luminescence emission behavior of the tracer over time may include determining a decay constant for one or more emission wavelengths or one or more wavelength ranges. The decay constant is understood to be the period of time in which the initial intensity of the emission falls i/e-fold. If the tracer is an XRF tracer, the X-ray fluorescence spectrum can be qualitatively analyzed to determine the identity of the tracer.

Determining a signal intensity of the identified tracer in the first material

The signal intensity of the identified tracer refers to the intensity of a signal that can be determined for a property of the identified tracer, such as an optical signal that is obtained after excitation of the tracer.

In particular if the tracer is a luminescent tracer, in order to determine the signal intensity of the tracer, i.e. to identify it, the luminescence behavior of the tracer can be analyzed with regard to a wide variety of properties.

In particular, it can be provided that the signal intensity of the tracer is determined

- measuring an emission spectrum of the tracer;

- measuring the luminescence emission behavior of the tracer over time;

- determining an intensity ratio between emission wavelengths of the tracer; orcomprises two or more thereof.

If the tracer is an XRF tracer, the intensity of the X-ray fluorescence radiation can be analyzed to determine the signal intensity of the tracer.

The analysis of the tracer properties used to identify the tracer and to determine a signal intensity of the identified tracer can be carried out using known spectroscopic methods, particularly in the case of luminescent tracers. In addition to spectrometers, photocells, photodiodes, phototransistors, photomultipliers, black-and-white cameras or color cameras can be used to analyze the tracer properties. Optical filters such as long pass/short pass/band pass filters can be used in the detection devices. The facilities mentioned can be used alone or in combination.

Particularly in the case of luminescent tracers, broad-band and/or narrow-band sources such as lasers, laser diodes, light-emitting diodes (LEDs), xenon lamps, halogen lamps can be used individually or in combination to stimulate luminescence. The excitation sources can be activated individually or activated simultaneously or sequentially in different combinations. Optical filters such as long pass/short pass/band pass filters can be used in the excitation devices. The excitation can be pulsed, ie the duration of the excitation can be limited in a defined time. With an XRF tracer, the tracer can be identified and the signal intensity of the identified tracer can be determined using X-ray sensors (e.g. XRF).

Based on the signal intensity of the tracer in a material, the concentration of the tracer in the material can be determined. For example, based on the determined signal intensity of a tracer in the first material, the concentration of the tracer in the first material can be determined. The signal intensity of the tracer in the material can be proportional to the concentration of the tracer in the material.

The value of the determined signal intensity can correlate with the concentration of the tracer. To establish this correlation, a raw intensity signal measured by the detection device can be converted into a signal intensity corresponding to the concentration, for example by multiplying it with a material-dependent conversion factor, or for example by comparing it with a calibration curve representing the relationship between the raw intensity signal and the tracer concentration become. The conversion factors and calibration curves can be determined by analyzing materials with different tracer concentrations.

Setting a target signal intensity

When setting the target signal intensity, a distinction must be made between two cases.

In a first case, the determined signal intensity (i.e. signal intensity of the identified tracer in the first material, which is determined according to the invention) is zero (in the case that the first material does not include a tracer) or smaller (in particular if the first Material contains the tracer in an amount that is less than the amount necessary to achieve the target signal intensity) than the target signal intensity. In this first case, a further amount of the identified tracer is added to the first material, with the amount of tracer necessary to achieve the target signal intensity being calculated or otherwise determined depending on the determined signal intensity can.

Adding the tracer, that is to say in particular further amounts of tracer, to the first material can be done by directly adding the tracer to the first material. For this purpose, it can be provided that the first material is suitably prepared before being added, in particular by crushing, grinding, homogenizing, etc. of the first material.

Alternatively, it can be provided that adding a further amount of the identified tracer into the first material is the addition of a masterbatch, the masterbatch comprising the recycled material and the tracer and the signal intensity of the masterbatch being greater than the target signal intensity. A masterbatch in the sense of the present disclosure is therefore a mixture, such as a blend, a fused mixed material, etc., of recycled material, in particular the same recycled material contained in the first material, and the tracer, the concentration in the masterbatch being higher as a tracer concentration necessary to achieve the target signal intensity. The masterbatch can be produced, for example, by adding the tracer to a subset of a substantially identical first material (recycled material with or without tracer). The masterbatch can contain higher, in particular significantly higher, concentrations of tracer in the recycled material compared to the first material. For example, the concentration of the tracer in the masterbatch can be twice as high, four times as high, ten times as high or five times as high as the concentration of the tracer in the first material.

It is expressly intended that the tracer is not added to the first material in combination with a virgin material, i.e. that the masterbatch consists only of the recycled material and the tracer. This ensures the direct connection between signal intensity in the final material, i.e. the material with a verifiable proportion of recycled material, and the proportion of recycled material contained therein.

In a second case, the determined signal intensity (i.e. signal intensity of the identified tracer in the first material, which is determined according to the invention) is greater (in particular if the first material contains the tracer in an amount that is greater than the amount which is necessary to achieve the target signal intensity) than the target signal intensity.

In this second case, the first material is "diluted", either by adding further recycled material, i.e. recycled material without tracer, or by adding a mixture of further recycled material and tracer, with a signal intensity of the mixture being lower than the target signal. Intensity, that is, a mixture containing the tracer in an amount that is less than the amount necessary to achieve the target signal intensity.

By adding a further amount of the identified tracer or adding further recycling material or a mixture of further recycling material and tracer according to the two alternative cases, a second material is obtained. The second material has the target signal intensity. The second material includes the recycled material, i.e. the same recycled material that was contained in the first material, and the tracer. In other words, the first material and the second material only differ in that the second material has the target signal intensity and the first material does not, i.e. that the second material contains the tracer in an amount that is suitable for the target -Signal intensity to be preserved and the first material is not.

The target intensity therefore corresponds to a proportion of 100% recycled material.

Optionally combining the second material with a third material

In a final process step, the second material, that is, the material with the target signal intensity, can be combined with a third material. The combining can include mixing, blending, fusing the two materials, such as mechanical mixing of previously comminuted, ground, homogenized materials. It can be provided that the third material is a virgin material or a further recycled material that is different from the recycled material contained in the first material, preferably the third material is a virgin material.

The combining takes place in a defined ratio, in particular weight ratio, of the second material and the third material. Recycled material regularly has poorer properties, such as mechanical properties, optical properties, etc., due to previous use. By mixing the recycled material with new material to produce a new product in a suitable ratio, the disadvantageous properties of the recycled material can be essentially compensated for. For this purpose, it can be provided that a ratio of recycled material to third material, in particular new material, is from i:ioo to 1:2, 1:50 to 1:2.5 or 1:20 to 1:3.

The method according to the invention allows the defined proportion of recycled material in the final product to be reliably determined, i.e. checked.

It can be provided that the material obtained with a verifiable proportion of recycled material is brought into the form of a final product following the method according to the invention, for example in the form of a window frame or part thereof, in the form of a bottle, etc.

Sorting process

It can be provided that the provision and/or the identification of the first material includes the separation of the first material from at least one foreign material, that is to say that the method according to the invention is preceded by a sorting process in which the first material is separated from other materials contained herein referred to as foreign materials, is separated.

The at least one foreign material differs from the first material in at least one property that allows separation. For example, the foreign material may be a second recycled material that is different from the recycled material contained in the first material, such as physically and/or chemically different. For example, the first material may include recycled PVC while the foreign material includes HDPE.

Likewise, the foreign material may be a material that comprises the same recycled material as the first material, in which case the foreign material comprises a marking agent, such as a second tracer or a watermark, etc., which allows the foreign material to be distinguished from the first material.

In particular, it can be provided that the foreign material contains a second tracer that is different from the tracer that is contained in the first material and/or is added to the first material.

For example, it can be provided that the first material is in a mixture with a first foreign material, a second foreign material, a third foreign material, etc. is present, wherein the first material contains a first tracer, the first foreign material contains a second tracer, the second foreign material contains a third tracer, etc., the tracers being different from one another. In this case, after identifying the first tracer, the first material can be separated from the other materials containing other tracers by suitable means (tracer based sorting). In this context, “other tracers” are not only chemically different tracers, but also different combinations, amounts, etc. of otherwise chemically similar tracers.

After processing sorted recycled material into new products, it may be intended to be able to sort the new products in the same way as the original first material or in a different way. By producing the second material, it is possible to control, in particular by suitable selection of the tracer, how the material obtained after combination with a third material can be sorted.

Technical effect

When recycling recycled material, tracers can be used to detect the recycled material in the end product. In this way, it can be checked whether there is a certain concentration of tracers that allows conclusions to be drawn about the amount or proportion of recycled material. However, the use of appropriate tracers means that, for example, some of the recycled material already contains tracers. Therefore, it is not sufficient if the same amount of tracer is always added to the recycled material, as this would lead to a constant increase in the tracer in the recycled material over time, which prevents the proportion of recycled material from being reliably checked.

The method according to the invention serves to produce a material with a verifiable proportion of recycled material. The material produced using the process therefore includes a proportion of recycled material. The proportion of recycled material in the material produced can be verified in such a way that the proportion of recycled material can be reliably determined without knowledge of the parameters of the manufacturing process, in particular without knowledge of the quantities of recycled material and optionally new material used in production.

Furthermore, the method according to the invention makes it possible to ensure correct sorting of products manufactured using recycled material.

Finally, the method according to the invention enables a quality check of a material produced using the method according to the invention, in particular with regard to the amount of recycled material contained.

General definitions

Unless expressly stated otherwise, a feature specified in the singular (a, an...) also includes the plural. For example, if it is stated that the If the composition according to the invention contains a tracer, this also includes the case in which the composition contains a mixture of several tracers.

Unless expressly stated otherwise, terms such as “comprising”, “containing” etc. include the meanings “substantially comprising”, “substantially containing” or “consisting of”.

Examples

The invention will be explained in detail below with reference to specific examples, whereby the invention is not limited to these examples, individual features of the examples in combination with the embodiments listed above can contribute to the realization of the invention.

In the following embodiments, the tracers Mi and M2 have the following chemical formulas

Ml: Gd1.69Ybo.24Ero.o7O3

M2: Gdi. ₇ 92Ybo.2Tmo.oo8O ₃

Example 1 fno tracer in the first material):

Used window frames made of PVC are delivered to recycling plant 1. The window frames are ground into granules and homogenized by mixing.

This ground material is analyzed spectroscopically, using the excitation range X = 935 nm to 985 nm and the emission ranges X = 1150 nm to 1900 nm and X = 520 nm to 820 nm are tested. A spectrally resolving detection device is used to analyze the fluorescence radiation. No fluorescence signal is detected, so the PVC material does not contain any fluorescence tracer.

The recycled material will be used again to produce PVC window frames. 25% recycled material and 75% virgin material are used in the production of these window frames. The proportion of recycled material in the window frames should be detectable using a fluorescence tracer.

For this purpose, the fluorescence tracer Ml (Gd1.69Ybo.24Ero.o7O3) is added to the recycling material. The tracer Ml is gadolinium oxide, doped with erbium and ytterbium and has an emission maximum at 6 2nm. The target content of 25% recycled material should lead to a signal intensity of 100 (au) at Ö72nm in the window frames. To determine the tracer concentration to be used, the relationship between signal intensity and tracer concentration is determined experimentally using 25% recycled material. For this purpose, the recycled material is mixed with different amounts of tracer. The fluorescence intensity of the recycled material is determined to enable later quality control of the production process. 25% of the recycled material is processed with 75% virgin material into test specimens representative of window frames and these are examined spectroscopically:

When 4ooppm Tracer Ml is added, the desired intensity of 100 is achieved on the test specimen. The modified recycling material shows an intensity of 400. Accordingly, the recycling company adds 400 ppm Tracer Ml to the regrind during the production process. To quality control the correct tracer addition, it is checked whether the modified recycling material has the target signal intensity of 400. The tracer is added by admixture. The recycling company makes the mixture produced (= second material/modified recycled material) available to the window manufacturer.

The window manufacturer uses 25% of modified recycled material and 75% virgin material to produce new window frames. The window frames are analyzed spectroscopically. An emission spectrum with an emission maximum at Ö72nm and a fluorescence intensity of 100 at the emission maximum are determined. The emission spectrum proves the identity of the tracer contained as Fluorescence Tracer Ml. The fluorescence intensity proves the content of 25% recycled material.

Example 2 f small amounts of tracer in the first material):

Used window frames made of PVC are delivered to recycling plant 2. The window frames already contain 25% recycled material. According to the manufacturer's information, the fluorescence tracer Ml is included to prove the proportion of 25% recycled material can. An emission spectrum with an emission maximum at 6 2nm is determined. The identity of the tracer contained is therefore proven to be a fluorescence tracer Mi.

The recycled material will be used again to produce PVC window frames, with 25% recycled material and 75% virgin material being used again. The proportion of 25% recycled material must be able to be proven using the fluorescence tracer Ml and a target signal intensity of 100 (a.u.) at Ö72nm.

According to the manufacturer's information, the tracer content in the window frames and therefore in the recycled material is already looppm. However, additional fluorescence tracer Ml must be added to the recycled material in order to prevent the tracer concentration from falling when mixed with virgin material.

To determine the additional tracer concentration to be used, the relationship between signal intensity and additional tracer concentration is determined experimentally when using 25% recycled material. For this purpose, the recycled material is mixed with different amounts of tracer. The fluorescence intensity of the recycled material is determined to enable later quality control of the production process. 25% of the recycled material is processed with 75% virgin material into test specimens representative of window frames and these are examined spectroscopically:

When ooppm Tracer Mi is added, the desired intensity of 100 is achieved on the test specimen. The modified recycling material shows an intensity of 400. Accordingly, the recycling company adds 300 ppm Tracer Ml to the regrind during the production process. To quality control the correct tracer addition, it is checked whether the modified recycling material has the target signal intensity of 400. The tracer is added by admixture. The recycling company makes the mixture produced (= second material/modified recycled material) available to the window manufacturer.

The window manufacturer uses 25% of modified recycled material and 75% virgin material to produce new window frames. The window frames are analyzed spectroscopically. An emission spectrum with an emission maximum at Ö72nm and a fluorescence intensity of 100 at the emission maximum are determined. The emission spectrum demonstrates the identity of the tracer contained as a fluorescence tracer Mi. The fluorescence intensity proves the content of 25% recycled material.

Example 3 (high amounts of tracer in the first material):

A mixture of used window frames from different product lines consisting of PVC is delivered to recycling plant 2. According to the manufacturer's information, the Fluorescence Tracers Ml is included. However, different product lines contain different concentrations of Ml. The recycled material will be used again to produce PVC window frames, using 25% recycled material and 75% virgin material. The proportion of 25% recycled material must be able to be proven using the fluorescence tracer Ml and a target signal intensity of 100 (a.u.) at 6 2nm.

The window frames are ground into granules and homogenized by mixing. To check the tracer Ml content, the mixture is analyzed spectroscopically. The emission spectrum of Ml with emission maximum at Ö72nm is determined. The identity of the tracer contained is therefore proven as Fluorescence Tracers Mi. However, an intensity of over 1000 au is found at Ö72nm. To achieve an intensity of 100 au using 25% recycled material, no further Tracer Ml may be added. Rather, recycled PVC must be mixed without tracers.

With the addition of 60% recycled PVC without tracer, the desired intensity of 100 is achieved on the test specimen. Accordingly, the recycling company adds 60% recycled PVC to the regrind in the production process and makes the resulting mixture (= second material/modified recycled material) available to the window manufacturer.

Example 4 (addition of tracer using masterbatch):

In a modification of example 2, the recycling company 2 does not add tracer by adding pure tracer Ml, but rather by adding a masterbatch. The masterbatch is produced by recycling company 3.

Various used PVC products are delivered to recycling plant 3. The entire material is ground into granules and homogenized by mixing. The ground material (= first material/recycled material) is analyzed spectroscopically. No fluorescence tracer is detected here, i.e. the PVC obtained has not yet been labeled.

The recycling company adds Tracer Ml to the regrind. This is done in a remelting process (compounding), whereby the tracer Ml is homogeneously melted into the HDPE. The melting product is processed into granules. During compounding, 10000 tracers are continuously added. The recycling company makes the granulate (masterbatch) obtained available to further processing companies.

Recycling plant 2 obtains the masterbatch from recycling plant 3 and adds the masterbatch to the regrind to achieve the necessary signal intensity. The additional masterbatch concentration to be used is determined experimentally. For this purpose, the recycled material is mixed with different amounts of masterbatch. The fluorescence intensity of the recycled material is determined. 25% of this doped recycled material is processed with 75% virgin material into test specimens representative of window frames and these are examined spectroscopically:

By mixing 96% regrind (concentration looppm) with 4% masterbatch (concentration öooppm), modified recycled material with 400 ppm tracer is obtained. To quality control the correct masterbatch addition, it is checked whether the modified recycling material has the target signal intensity of 400. New window frames are now made with 25% modified recycled material and 75% virgin PVC.

Example 5 (sorting process with second tracer):

Used transparent HDPE bottles are specifically separated from other plastic products using tracer-based sorting. For this purpose, the HDPE contains the tracer Ml with emission maximum at 6 2nm and the tracer M2 (Gdi^Ybo^Tmo.oosOa) with emission maximum at 79önm. Tracer Ml is gadolinium oxide doped with erbium and ytterbium. Tracer M2 is gadolinium oxide doped with erbium and thulium.

The amounts of Ml and M2 in HDPE are adjusted so that the intensity of Ml at Ö72nm is “25” and the intensity of M2 at 79nm is “50” in transparent HDPE. Based on the emission maxima and the intensity ratio 1:2, the HDPE is identified and sorted out.

HDPE sorted out in this way is delivered to a recycling plant. The entire material is ground into granules. This regrind is to be processed together with new HDPE to produce new HDPE bottles. 25% of this regrind and 75% new material should be used. The proportion of this ground material should be detectable using fluorescence spectroscopy. Furthermore, the intensity of the tracers in the new bottles should also be 25 or 50.

To compensate for the loss of intensity caused by mixing regrind with virgin material, additional tracers Ml and M2 must be added to the recycled material.

To determine the additional tracer concentrations to be used, the relationship between signal intensity and additional tracer concentration is determined experimentally when using 25% recycled material. For this purpose, the recycled material is mixed with different amounts of tracer. The fluorescence intensity of the recycled material is determined to enable later quality control of the production process. 25% of the recycled material is processed with 75% virgin material into test specimens representative of HDPE bottles. These are examined spectroscopically:

When adding 75 ppm Tracer Ml and isoppm Tracer M2, the desired intensity of 25 or 50 is achieved on the test specimen. Accordingly, the recycling company adds 75ppm Tracer Ml and isoppm Tracer M2 to the regrind in the production process. The recycling company makes the mixture produced (= second material/modified recycled material) available to the bottle manufacturer. This uses 25% of modified recycled material and 75% new material for production. When the bottles are analyzed spectroscopically, emission maxima are found at Ö72nm and 79önm with fluorescence intensities of 25 and 50. This proves the content of 25% recycled material. Furthermore, the new HDPE bottles with recycled material also show an intensity ratio of 1:2 and can be correctly identified and sorted using tracer based sorting.

Example 6f Sorting process with alternative marking agent:

Two manufacturers A and B produce machine-sortable HDPE bottles. For this purpose, manufacturer A uses Tracer Ml in the HDPE material. Manufacturer B uses a water brand on the bottles. During mechanical sorting, the bottles from manufacturer A are sorted using Tracer Mi using Tracer Based Sorting, and the bottles from manufacturer B are sorted using the water brand using optical image recognition. Manufacturers want to use HDPE recycled material in production. The recycled material content should be detectable using a uniform fluorescence tracer. Both manufacturers use Tracer M2 for this purpose.

Analogous to the processes described in the previous examples, the bottles are processed into granules after sorting. The presence of tracer M2 is checked by spectroscopic analysis and the amount of tracer M2 or recycled HDPE without tracer to be added is determined. In the same way, the amount of Tracer Ml to be added is determined to enable tracer-based sorting of bottles made with recycled material. The appropriately modified HDPE recycling materials are made available to the bottle manufacturers and can be used by them for production new bottles can be used. Spectroscopic analysis of the bottles produced proves the identity of the tracer contained as fluorescence tracer M2. Measuring the fluorescence intensity shows the content of recycled material.

The features of the invention disclosed in the above description and in the claims can be essential for the implementation of the invention in its various embodiments, both individually and in any combination.

Claims

Method for producing a material with a verifiable proportion of recycled material, the method comprising the steps:

- identifying the tracer in the first material;

- determining a signal intensity of the identified tracer in the first material;

- Setting a target signal intensity

- optionally combining the second material with a third material in a defined ratio, the third material being a material that does not contain the identified tracer, in order to obtain the material with a verifiable proportion of recycled material. A method for producing a material with a verifiable proportion of recycled material according to claim i, wherein the recycled material comprises a plastic. A method for producing a material with a verifiable proportion of recycled material according to claim 2, wherein the plastic is selected from the group consisting of polyvinyl chloride, polyethylene, polyethylene terephthalate, polystyrene, polypropylene polyamide, acrylonitrile-butadiene-styrene copolymer and a mixture of two or more of that. Method for producing a material with a verifiable proportion of recycled material according to one of the preceding claims, wherein the tracer is a luminescent substance. 5- A method for producing a material with a verifiable proportion of a recycled material according to one of the preceding claims, wherein the tracer comprises a rare earth metal, a side earth metal ion, a transition metal, a transition metal ion or a mixture of two or more thereof.

6. The method according to any one of the preceding claims, wherein the third material is a virgin material.

7. A method for producing a material with a verifiable proportion of recycled material according to one of the preceding claims, wherein identifying the tracer in the first material includes measuring an emission spectrum of the tracer, determining the presence and / or absence of an emission wavelength specific to the tracer, measuring the luminescence emission behavior of the tracer over time, measuring an emission intensity for one or more emission wavelengths of the tracer, determining an intensity ratio between emission wavelengths of the tracer or two or more thereof.

8. A method for producing a material with a verifiable proportion of recycled material according to one of the preceding claims, wherein determining a signal intensity of the identified tracer in the first material, measuring an emission spectrum of the tracer, measuring the luminescence emission behavior of the tracer over time, measuring an emission intensity for one or more emission wavelengths of the tracer, determining an intensity ratio between emission wavelengths of the tracer or two or more thereof.

9. A method for producing a material with a verifiable proportion of recycled material according to one of the preceding claims, wherein adding a further amount of the identified tracer into the first material is adding a masterbatch, the masterbatch comprising the recycled material and the tracer and the signal intensity of the masterbatch is greater than the target signal intensity.

10. A method for producing a material with a verifiable proportion of recycled material according to one of the preceding claims, wherein providing and/or identifying the first material comprises separating the first material from at least one foreign material.

11. A method for producing a material with a verifiable proportion of recycled material according to claim io, wherein the foreign material comprises a marking means that enables the foreign material to be distinguished from the first material.

12. A method for producing a material with a verifiable proportion of recycled material according to claim io or 11, wherein the foreign material contains a second tracer which is different from the tracer which is contained in the first material and/or is added to the first material.