Method for producing a material with verifiable proportion of recycled material

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

[0001] Process for producing a material with verifiable proportion of recycled material

[0002] Field of the invention

[0003] The present invention relates to a method for producing a material with a verifiable proportion of a recycled material.

[0004] Background of the invention

[0005] The reuse (recycling) of recycled materials, i.e. materials derived from old products, is essential to conserve raw material resources and reduce the costs of manufacturing new products.

[0006] To reuse materials, recycled material can be processed into new products. When manufacturing 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.

[0007] 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 verified or determined retrospectively without knowledge of the manufacturing process parameters.

[0008] Object of the invention

[0009] It is therefore the object of the present invention to provide a method for producing a material with a verifiable proportion of recycled material which overcomes disadvantages of the prior art, in particular to provide a method for producing a product comprising recycled material, wherein the proportion of a recycled material in the product can be controlled, in particular after the production of the product.

[0010] Disclosure of the invention

[0011] This object is achieved according to the subject matter of the independent claims. Preferred embodiments emerge from the subclaims and the following description.

[0012] The object is achieved in particular by a method for producing a material with a verifiable proportion of recycled material, the method comprising the steps:

[0013] - Providing a first material, wherein the first material consists of a recycled material and optionally a tracer;

[0014] - Identifying the tracer in the first material;

[0015] - Determining a signal intensity of the identified tracer in the first material; - Setting a target signal intensity by

[0016] - 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

[0017] - adding further recycled material or a mixture of further recycled material and tracer, wherein a signal intensity of the mixture is lower than the target signal intensity if the determined signal intensity is higher than the target signal intensity, to obtain a second material comprising the recycled material and the tracer and having the target signal intensity; and

[0018] - optionally combining the second material with a third material in a defined ratio, wherein the third material is a material that does not contain the identified tracer, in order to obtain the material with a verifiable proportion of a recycled material.

[0019] Proceedings

[0020] The method according to the invention serves to produce a material with a verifiable proportion of recycled material. The material produced by the method thus comprises a proportion of recycled material and optionally a proportion of another material, for example, a virgin material. The proportion of recycled material in the produced material is verifiable in such a way that the proportion of recycled material can be reliably determined without knowledge of the parameters of the production process, in particular without knowledge of the quantities of recycled material and optionally another material used in production.

[0021] Providing initial material

[0022] The provision of the first material may comprise a suitable preparation of the first material for further processing, in particular the comminution, grinding, homogenization, etc. of the first material.

[0023] First material

[0024] The first material consists of a recycled material and optionally a tracer. If the first material does not include a tracer, the first material consists only of the recycled material.

[0025] For the purposes of the present disclosure, a recycled material is a post-consumer material, i.e., waste material from households, commercial, industrial, and institutional facilities, or a post-industrial material, i.e., production waste and / or production rejects. The first material may be in the form of a finished product, for example, in the form of a window frame or part thereof, in the form of a bottle, etc.

[0026] The recycled material may 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, in each case based on the total weight of the recycled material, or consist of a plastic.

[0027] The plastic may 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 thereof.

[0028] Tracer

[0029] A tracer within the meaning of the present disclosure is a marker, i.e., for example, a substance or material that can be used for identifying, sorting, etc., a marked material. The tracer according to the invention can also be suitable for determining the proportion of marked materials in compositions comprising several materials.

[0030] The tracer may be a luminescent substance, in particular a photoluminescent substance.

[0031] Photoluminescence is the emission of photons from direct photoexcitation of any form of matter following 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 downshift process. Conversely, photon upconversion is an optical process in which the energy of the emitted photons is greater than the energy of the absorbed photons. Both excitation and emission can occur in UV, visible, or infrared (IR) light.

[0032] To be applicable as tracers, 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 properties 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.

[0033] It can be provided that the tracer comprises a rare earth metal, a rare 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. Further preferred metals are In, Bi, Ba, Sr, Ca, Zn, Mg, and mixtures thereof. Particularly preferred tracers can be based on YBaZn or YBaZnF.

[0034] According to one embodiment, particularly preferred tracers may have the chemical formula i:

[0035] M2(iyz)Yb2yRem2zAD0 5-xHal2x (Chemical Formula 1), wherein 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 0 to 1; z is from 0 to 1; at least one of y and z is at least 0.001, the total of y + z is at most 1.

[0036] Preferred embodiments of the chemical formula 1 and their preparation are described in EP 3 431570 Bi.

[0037] Other preferred tracers are oxysulfides doped with rare earth elements.

[0038] According to one embodiment, these tracers may have the chemical formula 2:

[0039] M 2-x Rem x 02S (Chemical Formula 2) where M is at least one element selected from Y, Gd, La and mixtures thereof, Rem is at least one rare earth element.

[0040] Preferred tracers can be based on yttrium oxysulfide (YOS) or gadolinium oxysulfide (GOS).

[0041] Particularly preferred tracers may be based on yttrium oxysulfide (YOS), gadolinium oxide or gadolinium oxysulfide (GOS), each doped with ytterbium and erbium or doped with ytterbium and holmium.

[0042] According to a further embodiment, particularly preferred tracers may have the chemical formula 3:

[0043] 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 are independently 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 0 to 3, although at least one of (a) and (b) is greater than 0, at least one of (d) and (e) is greater than 0 and at least one of (w), (x), (y) and (z) is greater than 0; where the sum of (a)+(b)+(c)=i-2, preferably 1 or 2, and the sum of (w)+(x)+(y)+(z)=2 or 3, optionally with the proviso that (c) > 0.

[0044] Preferably, it can be provided that Wei = Ce, D01 = Er and (b) = (e) = (w) = (y) = (z) = o, where (x) > o.

[0045] It may 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.

[0046] Preferred embodiments and their manufacture are described in EP3375840B1.

[0047] The tracer can be an XRF tracer. An XRF tracer is a tracer that can be detected by X-ray fluorescence analysis (XRF). The XRF tracer can, for example, be formed by defined amounts of one or more chemical elements.

[0048] Identifying the tracer in the first material

[0049] In particular, if the tracer is a luminescent tracer, the luminescence behavior of the tracer can be analyzed with regard to various properties in order to determine the identity of the tracer, ie to identify it.

[0050] In particular, it can be provided that the identification of the tracer in the first material

[0051] - measuring an emission spectrum of the tracer;

[0052] - determining the presence and / or absence of an emission wavelength specific for the tracer;

[0053] - measuring the luminescence emission behavior of the tracer over time;

[0054] - measuring an emission intensity for one or more emission wavelengths of the tracer;

[0055] - determining an intensity ratio between emission wavelengths of the tracer; or two or more thereof.

[0056] Instead of analyzing defined emission wavelengths, wavelength ranges can also be analyzed.

[0057] Measuring the tracer's luminescence emission behavior over time can involve determining a decay constant for one or more emission wavelengths or wavelength ranges. The decay constant is defined as the time period in which the initial emission intensity decays to i / e times. If the tracer is an XRF tracer, the X-ray fluorescence spectrum can be qualitatively analyzed to determine the tracer's identity.

[0058] Determining a signal intensity of the identified tracer in the first material

[0059] 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 obtained after excitation of the tracer.

[0060] In particular, if the tracer is a luminescent tracer, the luminescence behavior of the tracer can be analyzed with regard to various properties in order to determine the signal intensity of the tracer, ie to identify it.

[0061] In particular, it can be provided that the determination of the signal intensity of the tracer

[0062] - measuring an emission spectrum of the tracer;

[0063] - measuring the luminescence emission behavior of the tracer over time;

[0064] - measuring an emission intensity for one or more emission wavelengths of the tracer;

[0065] - determining an intensity ratio between emission wavelengths of the tracer; or two or more thereof.

[0066] Instead of analyzing defined emission wavelengths, wavelength ranges can also be analyzed.

[0067] 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.

[0068] The analysis of the tracer properties used to identify the tracer and to determine the signal intensity of the identified tracer can be performed 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 / bandpass filters can be used in the detection devices. These devices can be used alone or in combination.

[0069] Particularly with luminescent tracers, broadband and / or narrowband sources such as lasers, laser diodes, light-emitting diodes (LEDs), xenon lamps, and halogen lamps can be used individually or in combination to excite the luminescence. The excitation sources can be activated individually, simultaneously, or sequentially in various combinations. Optical filters such as long-pass / short-pass / band-pass filters can be used in the excitation devices. Excitation can be pulsed, meaning the duration of the excitation can be limited in time. With an X-ray tracer, the tracer can be identified and its signal intensity determined using an X-ray sensor (e.g., X-ray scanning).

[0070] 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.

[0071] The value of the determined signal intensity can correlate with the tracer concentration. 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 by a material-dependent conversion factor or by comparing it with a calibration curve representing the relationship between the raw intensity signal and the tracer concentration. The conversion factors and calibration curves can be determined by analyzing materials with different tracer concentrations.

[0072] Setting a target signal intensity

[0073] When setting the target signal intensity, a distinction must be made between two cases.

[0074] 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 comprise a tracer) or smaller (in particular, if the first material contains the tracer in an amount smaller than the amount necessary to achieve the desired signal intensity) than the desired signal intensity. In this first case, a further amount of the identified tracer is added to the first material, wherein the amount of tracer necessary to achieve the desired signal intensity can be calculated or otherwise determined depending on the determined signal intensity.

[0075] The addition of the tracer, in particular additional amounts of tracer, to the first material can be carried out by directly dosing the tracer into the first material. For this purpose, the first material can be suitably prepared before addition, in particular by comminuting, grinding, homogenizing, etc.

[0076] Alternatively, it can be provided that the addition of a further amount of the identified tracer to the first material is the addition of a masterbatch, wherein the masterbatch comprises the recycled material and the tracer, and the signal intensity of the masterbatch is greater than the target signal intensity. A masterbatch within the meaning of the present disclosure is therefore a mixture, such as a blend, a fused mixed material, etc., of recycled material, in particular of the same recycled material contained in the first material, and the tracer, wherein the concentration in the masterbatch is higher than a tracer concentration necessary to achieve the target signal intensity. The masterbatch can be produced, for example, by dosing the tracer into a subset of a substantially identical first material (recycled material with or without tracer).The masterbatch may contain higher, especially significantly higher, tracer concentrations in the recycled material compared to the first material. For example, the tracer concentration in the masterbatch may be twice, four times, ten times, or five times higher than the tracer concentration in the first material.

[0077] It is expressly stipulated that the tracer is not added to the first material in combination with a virgin material, i.e., that the masterbatch consists solely of the recycled material and the tracer. This ensures a direct correlation between the signal intensity in the final material, i.e., the material with a verifiable recycled content, and the recycled content.

[0078] In a second case, the determined signal intensity (ie 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 which is greater than the amount which is necessary to achieve the desired signal intensity) than the desired signal intensity.

[0079] 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, whereby a signal intensity of the mixture is lower than the target signal intensity, i.e. a mixture that contains the tracer in an amount that is smaller than the amount necessary to achieve the target signal intensity.

[0080] By adding a further amount of the identified tracer or by adding further recycled material or a mixture of further recycled material and tracer according to the two alternative cases, a second material is obtained. The second material has the desired signal intensity. The second material comprises 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 differ only in that the second material has the desired signal intensity and the first material does not, i.e., the second material contains the tracer in an amount suitable to obtain the desired signal intensity and the first material does not.

[0081] The target intensity therefore corresponds to a share of 100% recycled material.

[0082] Optionally combining the second material with a third material

[0083] In a final process step, the second material, i.e., the material with the desired signal intensity, can be combined with a third material. The combining can involve mixing, blending, or fusing the two materials, such as mechanically blending previously crushed, ground, or homogenized materials. The third material can be a virgin material or another recycled material that is different from the recycled material contained in the first material; preferably, the third material is a virgin material.

[0084] The combination takes place in a defined ratio, particularly by weight, of the second material and the third material. Due to previous use, recycled material generally exhibits inferior properties, such as mechanical properties, optical properties, etc. By mixing the recycled material with virgin material to produce a new product in a suitable ratio, the disadvantageous properties of the recycled material can be substantially compensated. For this purpose, a ratio of recycled material to third material, particularly virgin material, can be provided for in the range of 1:100 to 1:2, 1:50 to 1:2.5, or 1:20 to 1:3.

[0085] The method according to the invention makes it possible to reliably determine, i.e., check, the defined proportion of a recycled material in the final product.

[0086] It can be provided that the material obtained with a verifiable proportion of a recycled material is brought into the form of a final product following the process according to the invention, for example in the form of a window frame or a part thereof, in the form of a bottle, etc.

[0087] Sorting process

[0088] It can be provided that the provision and / or identification of the first material comprises 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, which are referred to herein as foreign materials.

[0089] 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 differs from the recycled material contained in the first material, such as being physically and / or chemically different. For example, the first material may comprise recycled PVC, while the foreign material comprises HDPE.

[0090] 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., that allows the foreign material to be distinguished from the first material.

[0091] In particular, it can be provided that the foreign material contains a second tracer which is different from the tracer which is contained in the first material and / or added to the first material.

[0092] For example, it can be provided that the first material is present in a mixture with a first foreign material, a second foreign material, a third foreign material, etc., 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., wherein the tracers are different from one another. In this case, after the first tracer has been identified, 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 to be understood not only as chemically different tracers, but also as different combinations, amounts, etc. of otherwise chemically similar tracers.

[0093] 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, in particular by appropriately selecting the tracer, it is possible to control how the material obtained after combining with a third material can be sorted.

[0094] Technical effect

[0095] When recycling recycled material, tracers can be used to detect the recycled material in the final product. This allows for monitoring whether a certain concentration of tracers is present, which allows conclusions to be drawn about the amount or proportion of recycled material. However, the use of such tracers can lead to, for example, some of the recycled material already containing tracers. Therefore, it is not sufficient to always add the same amount of tracer to the recycled material, as this would lead to a steady increase in the tracer content in the recycled material over time, which would prevent reliable verification of the recycled material content.

[0096] 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 contains a proportion of recycled material. The proportion of recycled material in the produced material is verifiable in such a way that the proportion of recycled material can be reliably determined without knowledge of the parameters of the production process, in particular without knowledge of the quantities of recycled material and optionally virgin material used in production.

[0097] Furthermore, the method according to the invention makes it possible to ensure correct sorting of products manufactured using recycled material.

[0098] Finally, the method according to the invention enables a quality check of a material produced according to the method according to the invention, in particular with regard to the amount of recycled material contained.

[0099] General definitions

[0100] Unless expressly stated otherwise, a feature stated in the singular (a, an...) also includes the plural. For example, if it is stated that the composition according to the invention contains a tracer, this also includes the case where the composition contains a mixture of several tracers.

[0101] Unless expressly stated otherwise, terms such as “comprising”, “containing”, etc. include the meanings “essentially comprising”, “essentially containing” or “consisting of”.

[0102] Examples

[0103] In the following, the invention will be explained in detail with reference to concrete 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.

[0104] In the following examples, the tracers Mi and M2 have the following chemical formulas

[0105] Ml: Gd1.69Ybo.24Ero.o7O3

[0106] M2: Gdi.792Ybo.2Tmo.oo8O3

[0107] Example 1 (no tracer in the first material):

[0108] Used PVC window frames are delivered to Recycling Plant 1. The window frames are ground into granules and homogenized by mixing.

[0109] 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. A spectrally resolved detection system is used to analyze the fluorescence radiation. No fluorescence signal is detected, thus the PVC material does not contain a fluorescence tracer.

[0110] The recycled material will be reused to manufacture PVC window frames. The production of these window frames will be comprised of 25% recycled material and 75% virgin material. The proportion of recycled material in the window frames will be detectable using a fluorescent tracer.

[0111] For this purpose, the fluorescence tracer Ml (Gd1.69Ybo.24Ero.o.7O3) is added to the recycled material. The tracer Ml is gadolinium oxide doped with erbium and ytterbium and exhibits an emission maximum at 62 nm. The targeted content of 25% recycled material should result in a signal intensity of 100 (au) at 72 nm for 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 subsequent quality control of the production process. 25% of the recycled material is combined with 75% virgin material to produce test specimens representative of window frames, which are then subjected to spectroscopic analysis:

[0112] With the addition of 40 ppm Tracer MI, the desired intensity of 100 is achieved on the test specimen. The modified recycled material exhibits an intensity of 400. Accordingly, the recycling company adds 400 ppm Tracer MI to the ground material during the production process. To ensure the correct addition of tracer, it is checked whether the modified recycled material has the desired signal intensity of 400. The tracer is added by admixture. The recycling company provides the resulting mixture (= second material / modified recycled material) to the window manufacturer.

[0113] The window manufacturer uses 25% of the 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 72 nm and a fluorescence intensity of 100 at the emission maximum is determined. The emission spectrum confirms the identity of the tracer contained as fluorescence tracer M1. The fluorescence intensity confirms the content of 25% recycled material.

[0114] Example 2 (small amounts of tracer in the first material):

[0115] Used PVC window frames are delivered to Recycling Facility 2. The window frames already contain 25% recycled material. According to the manufacturer's information, the fluorescence tracer Ml is included to demonstrate the 25% recycled material content. An emission spectrum with an emission maximum at 62 nm is detected. The identity of the tracer contained is therefore confirmed as fluorescence tracer Mi.

[0116] The recycled material is to be reused to manufacture PVC window frames, again using 25% recycled material and 75% virgin material. The 25% recycled material content must be verified using the fluorescence tracer MI and a target signal intensity of 100 (au) at 72 nm.

[0117] According to the manufacturer, the tracer content in the window frames, and thus in the recycled material, is already looppm. However, additional fluorescent tracer Ml must be added to the recycled material to prevent a decrease in the tracer concentration when mixed with virgin material.

[0118] To determine the additional tracer concentration to be used, the relationship between signal intensity and additional tracer concentration is experimentally determined 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 subsequent quality control of the production process. 25% of the recycled material is combined with 75% virgin material to create test specimens representative of window frames, which are then subjected to spectroscopic analysis:

[0119] With the addition of 0 ppm Tracer M1, the desired intensity of 100 is achieved on the test specimen. The modified recycled material exhibits an intensity of 400. Accordingly, the recycling company adds 300 ppm Tracer M1 to the ground material during the production process. To ensure the correct addition of tracer, it is checked whether the modified recycled material has the desired signal intensity of 400. The tracer is added by admixture. The recycling company provides the resulting mixture (= second material / modified recycled material) to the window manufacturer.

[0120] The window manufacturer uses 25% of the 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 72 nm and a fluorescence intensity of 100 at the emission maximum is determined. The emission spectrum confirms the identity of the tracer contained as fluorescence tracer Mi. The fluorescence intensity confirms the 25% recycled material content.

[0121] Example 3 (high amounts of tracer in the first material):

[0122] A mixture of used PVC window frames from various product lines is delivered to Recycling Plant 2. According to the manufacturer's information, the fluorescence tracer MI is included. However, the different product lines contain different concentrations of MI. The recycled material is to be reused to manufacture PVC window frames, with 25% recycled material and 75% virgin material being used. The 25% recycled material content must be verified using the fluorescence tracer MI and a target signal intensity of 100 (au) at 62 nm.

[0123] The window frames are ground into granules and homogenized by mixing. To check the tracer MI content, the mixture is analyzed spectroscopically. The emission spectrum of MI is determined, with an emission maximum at δ72 nm. The identity of the tracer present is therefore confirmed as fluorescence tracer MI. However, an intensity of over 1000 au is found at δ72 nm. To achieve an intensity of 100 au when using 25% recycled material, no additional tracer MI may be added. Instead, recycled PVC without tracer must be added. By adding 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 ground material during the production process and provides the resulting mixture (= second material / modified recycled material) to the window manufacturer.

[0124] Example 4 (adding the tracer via masterbatch):

[0125] In a variation of Example 2, Recycling Plant 2 does not add tracer by adding pure Tracer M1, but by adding a masterbatch. The masterbatch is produced by Recycling Plant 3.

[0126] Various used PVC products are delivered to Recycling Plant 3. All the material is ground into granules and homogenized by mixing. The ground material (= primary material / recycled material) is analyzed spectroscopically. No fluorescence tracer is detected during this process, meaning the resulting PVC has not yet been labeled.

[0127] The recycling company adds the tracer MI to the ground material. This occurs in a remelting process (compounding), in which the tracer MI is homogeneously melted into the HDPE. The remelting product is processed into granules. During compounding, tracer is continuously added. The recycling company makes the resulting granules (masterbatch) available to further processing companies.

[0128] Recycling plant 2 obtains the masterbatch from recycling plant 3 and adds it to the ground material to achieve the required 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 enhanced recycled material is combined with 75% virgin material to produce test specimens representative of window frames, which are then subjected to spectroscopic analysis:

[0129] By mixing 96% regrind (concentration 100 ppm) with 4% masterbatch (concentration 100 ppm), modified recycled material with 400 ppm tracer is obtained. To ensure the correct masterbatch addition, the modified recycled material is tested to ensure it meets the target signal intensity of 400 ppm. New window frames are now manufactured with 25% modified recycled material and 75% virgin PVC.

[0130] Example 5 (sorting process with second tracer):

[0131] Used transparent HDPE bottles are specifically separated from other plastic products using tracer-based sorting. The HDPE contains tracer M1 with an emission maximum at 62 nm and tracer M2 (GdI^2YbO^2TmO^2Oa) with an emission maximum at 79 nm. Tracer M1 is gadolinium oxide doped with erbium and ytterbium. Tracer M2 is gadolinium oxide doped with erbium and thulium.

[0132] The amounts of Ml and M2 in the HDPE are adjusted so that the intensity of Ml at δ72 nm is "25" and the intensity of M2 at 79 nm is "50" in transparent HDPE. Based on the emission maxima and the intensity ratio of 1:2, the HDPE is identified and sorted.

[0133] HDPE sorted in this way is delivered to a recycling plant. The entire material is ground into granules. This ground material will be processed together with virgin HDPE to produce new HDPE bottles. 25% of this ground material and 75% virgin material will be used. The proportion of this ground material will be detectable by fluorescence spectroscopy. Furthermore, the tracer intensity in the new bottles should also be 25 or 50.

[0134] 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.

[0135] To determine the additional tracer concentrations required, the relationship between signal intensity and additional tracer concentration is experimentally determined 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 subsequent quality control of the production process. 25% of the recycled material is combined with 75% virgin material to create test specimens representative of HDPE bottles. These are then analyzed spectroscopically:

[0136] By adding 75 ppm Tracer M1 and 75 ppm Tracer M2, the desired intensity of 25 and 50, respectively, is achieved on the sample. Accordingly, the recycling company adds 75 ppm Tracer M1 and 75 ppm Tracer M2 to the ground material during the production process. The recycling company provides the resulting mixture (= second material / modified recycled material) to the bottle manufacturer, who uses 25% of the modified recycled material and 75% virgin material for production. Spectroscopic analysis of the bottles reveals emission maxima at δ72 nm and 79 nm with fluorescence intensities of 25 and 50, respectively. This confirms the 25% recycled material content. Furthermore, the new HDPE bottles with recycled material also exhibit an intensity ratio of 1:2 and can be correctly identified and sorted using tracer-based sorting.

[0137] Example 6 f Sorting process with alternative marking agent:

[0138] Two manufacturers, A and B, produce machine-sortable HDPE bottles. Manufacturer A uses Tracer M1 in the HDPE material. Manufacturer B uses a water mark on the bottles. During machine sorting, the bottles from manufacturer A are sorted using Tracer M1 via tracer-based sorting, while the bottles from manufacturer B are sorted using the water mark via optical image recognition. The manufacturers want to use HDPE recycled material in their production. The recycled material content should be detectable using a uniform fluorescent tracer. For this purpose, both manufacturers use Tracer M2.

[0139] Analogous to the processes described in the previous examples, the bottles are processed into granules after sorting. Spectroscopic analysis is used to check for the presence of tracer M2, and the amount of tracer M2 or recycled HDPE without tracer to be added is determined. Similarly, the amount of tracer M1 to be added is determined to enable tracer-based sorting of bottles made with recycled material. The appropriately modified recycled HDPE materials are made available to the bottle manufacturers, who can use them to produce new bottles. Spectroscopic analysis of the produced bottles confirms the identity of the tracer contained as fluorescence tracer M2. Measuring the fluorescence intensity indicates the recycled material content.

[0140] The features of the invention disclosed in the above description and in the claims may be essential both individually and in any combination for the realization of the invention in its various embodiments.

Claims

Method for producing a material with a verifiable proportion of recycled material, wherein the method comprises the following steps: - Providing an initial material, the initial material consisting of a recycled material and optionally a tracer; - Identifying the tracer in the first material; - Determining the 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, wherein the signal intensity of the mixture is lower than the target signal intensity when the determined signal intensity is higher than the target signal intensity, in order to obtain a second material comprising the recycled material and the tracer and having the target signal intensity; and - Optionally, combining the second material with a third material in a defined ratio, wherein the third material is a material that does not contain the identified tracer, 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 thereof. A method for producing a material with a verifiable proportion of recycled material according to any one of the preceding claims, wherein the tracer is a luminescent substance. 5- Method for producing a material with a verifiable proportion of a recycled material according to any 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. Method according to 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 any of the preceding claims, wherein identifying the tracer in the first material comprises 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 wavelength(s) of the tracer, and determining an intensity ratio between emission wavelengths of the tracer or two or more thereof.

8. Method for producing a material with a verifiable proportion of recycled material according to any of the preceding claims, wherein determining a signal intensity of the identified tracer in the first material comprises 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 wavelength(s) of the tracer, determining an intensity ratio between emission wavelengths of the tracer or two or more thereof.

9. 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 to the first material is the addition of a masterbatch, wherein the masterbatch comprises the recycled material and the tracer and the signal intensity of the masterbatch is greater than the target signal intensity.

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

11. Method for producing a material with a verifiable proportion of recycled material according to claim 10, wherein the foreign material comprises a marking agent that enables differentiation of the foreign material from the first material.

12. Method for producing a material with a verifiable proportion of recycled material according to claim 10 or 11, wherein the foreign material contains a second tracer which is different from the tracer which is contained in and / or added to the first material.

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