Labelling plastic for recycling

Abstract

The present invention is related to a plastic packaging material, the material comprising: - a first label readable by an end-user, wherein the first label is visible to the end-user and distinct for packaging material that is recyclable; and - a second label readable by at least one industrial waste sorting machine, wherein the second label comprises information on the material origin, type and / or use, and wherein the second label is at least one up-conversion based florescent marker that is invisible to the end-user.

Description

[0001] LABELLING PLASTIC FOR RECYCLING

[0002] FIELD OF THE INVENTION

[0003] The present invention relates to plastic packaging material with a labelling system that enables the packaging material to be more efficiently and correctly recycled. In particular, the labelling system is at least a double labelling system. The plastic packaging material comprises at least a first label targeting the end-user and the second label targeting an industrial waste sorting machine.

[0004] BACKGROUND OF THE INVENTION

[0005] Plastic materials are widely used in the packaging industry because of plastic's ability to protect a product from physical damage, loss, and other degradation. Also, plastic material enables the product packaged within to reach the consumer in the same state it was in when packaged at the time of distribution.

[0006] Current recycling rates of packaging material are limited by poor sorting of plastic waste because of end-users not throwing the plastic packaging material into the right dustbin. As a result, the collection sorting efficiency of plastic waste is low. End-users are often confronted with numerous labels for prescribed disposal of the packaging material. The variety of labels confuses the end-user and may lead to the wrong disposal of a significant amount of packaging material. Even the material, which is disposed in a correct way, cannot always be identified by modern waste sorting equipment, which leads to the recycling rate for the most popular packaging polymer materials (PE, PP, PS) being below 10% from overall quantity.

[0007] Further, the currently used labels are mostly printed visible barcodes, and trademarks can be read and optically recognized by the human eye and by detectors in the wate management industry, provided they are placed / held in some defined way. These labels can hardly be recognized by current automated plastic waste sorting equipment due to a combination of reasons, namely: low detection time (milliseconds), random orientation of plastic packaging in detection unit, and high extent of deformation of plastic packaging as they are collected and processed by waste collecting companies. The combination of these three reasons makes the currently used labels simply unreadable, as they become unrecognizable when the packaging material reaches the waste management industry.

[0008] The low recycling rates results in most plastic packaging material ending up in incinerators or in landfills contributing to air pollution and climate change. Accordingly, there is still a need in the art for a more efficient means of labelling plastic packaging material so that the plastics are correctly disposed and subsequently collected and properly recycled.

[0009] DESCRIPTION OF THE INVENTION

[0010] The present invention attempts to solve the problems above by providing a plastic packaging material that is labelled such that it can be efficiently recycled. In particular, the material comprises at least two different labels, a first and a second label. More in particular, the first label enables the end-user, namely the human being who used the packaging material to dispose of the material appropriately. More in particular, the enduser throws the packaging material in the appropriate and correct rubbish bin as a result of the first label on or printed on the packaging material. The second label enables the correctly disposed packaging material to be further sorted by the waste management industry accurately. In particular, the second label targets the waste management industry and not the end user and is therefore invisible to the end user. Packaging material with at least two labels according to any aspect of the present invention enables the packaging material to be correctly disposed and subsequently collected and properly recycled thus reducing the amount of waste, particularly plastic waste.

[0011] According to one aspect of the present invention, there is provided plastic packaging material, the material comprising:

[0012] - a first label readable by an end-user, wherein the first label is visible to the end-user and distinct for packaging material that is recyclable; and

[0013] - a second label readable by at least one industrial waste sorting machine, wherein the second label comprises information on the material origin, type and / or use and wherein the second label is at least one up-conversion based florescent marker that is invisible to the end-user.

[0014] In particular, the packaging material is marked with a first mark (a first label), particularly a visible label to the naked eye, which is clearly distinguishable and easily recognizable by the end-user. The first label may be used uniformly on all packaging material such that all material of the same origin may be disposed in the same manner. For example, if the packaging material is plastic, then all plastic packaging material may comprise or be printed with the same or similar first label such that all the plastic packaging material with the same or similar first label is disposed the same way. The first label being clearly distinguishable and possibly uniform, enables the end-user to make a quick decision on the right disposal (right trash bin) to throw the packaging material away. This improves the quality of waste sorting due to reduction of wrong disposal decisions by the end-user. The correct disposal of packaging material by the end user increases the fraction of packaging materials, particularly plastic packaging material, accessible for recycling. More in particular, the first label enables the end-user to appropriately recycle the packaging material.

[0015] Examples of the first label according to any aspect of the present invention may be visible and eye-catching symbols and / or words. For example, the first label may be the sign for ‘Grune Punkt’ in used in Germany or equivalents found internationally. The distinct types of labels that may be used to target the end-user to throw the packaging material into the right rubbish bin may vary depending on the country where the packaging material is found in. Regardless of different terminology or labels used in different countries to describe different distinct means of disposal of a packaging material, the overall concept of the labelling according to any aspect of the present invention is the same and applicable in any one of these countries. For example, the first label according to any aspect of the present invention may be the sign for ‘Grune Punkt’ in used in Germany or equivalents found internationally. In another example, the first label according to any aspect of the present invention may be a sign for recycling, and / or in combination with the word recyclable. In another example, instead of symbols, the first label according to any aspect of the present invention may comprise word combinations such as “for plastics bin only”, “dispose as plastics waste for proper recycling”, “packaging disposable as plastics waste only for recycling”, “this packaging will be recycled, if disposed as plastics waste” etc. In particular, the packaging material according to any aspect of the present invention may comprise only a single first label, not to confuse the end-user. In another example, the packaging material may comprise more than one first label when the packaging material is to be used internationally and each country in which the packaging material ends up in has a different label for recyclable material.

[0016] The term ‘equivalents’ as used herein refers to different terminology or symbols for the same or similar recycling quality of a packaging material that is used in different countries. For example, the packaging materials that can be recycled in UK may be the same as the packaging materials that can be recycled in Germany. However, they may be labelled differently in each of these countries. The same recycling capability of a packaging material may be labelled under a different term in each of these countries. ‘Equivalents’ thus refers to the same or significantly similar first labels that are used different countries for the same packaging material. The same packaging material is further marked with a second mark (a second label), that may not necessarily be visible to the naked eye of the end-user. In particular, the second label on the packaging material according to any aspect of the present invention may be invisible to the end-user, with information at least on material origin and recycling recommendation. More in particular, the second label contains information on the kind of material, material origin, manufacturer, brand owner, purpose of packaging material, etc. This information is stored in for example a digital product passport that is or part of the second label. The information of the digital product passport may be read by at least one industrial waste sorting machine, particularly, the digital product passport may be accessible for high-speed optical analytics systems that are usually installed in automated waste sorting machines. In particular, because the second label is at least one up- conversion based florescent marker that is invisible to the end-user, the second label may be recognised by currently used industrial waste sorting machines where the detection time is low, namely milliseconds. Further, the second label being a fluorescent marking that is continuous and / or invisible for the human eye enables the plastic packaging according to any aspect of the present invention to be recognizable at any orientation and with any deformation.

[0017] In particular, the digital product passport stores all relevant information on the packaging material according to any aspect of the present invention online in a compressed form. This digital product passport is in the form of the second label on the packaging material. In one example, the second label may be a QR code that may be read or scanned by the waste sorting machine. By scanning the QR code on the packaging material, information on the packaging material may be accessed by the waste sorting machine which may be stored in a database (product passport register). The use of digital product passport is intended to ensure efficient and accurate recycling of packaging material. Further, the use of the digital product passport also reduces human error by making the process more automatic and digital.

[0018] The second label according to any aspect of the present invention may be a fluorescent marker, or a one up-conversion based florescent marker.

[0019] The ‘up-conversion-based florescent marker’ used according to any aspect of the present invention refers to a volume-based marking of the packaging plastic material. That is to say, the plastic packaging material does not comprise visible markers as the second label, but the plastic is in itself manufactured with the second label (i.e. the up-conversion-based florescent marker) integrated in the plastic. The markers used according to any aspect of the present invention is thus part of the plastic material (i.e. the polymer). The plastic according to any aspect of the present invention is thus combined with the up-conversion fluorescent marker during the manufacturing process of the packaging material and / or during the extrusion process of the packaging material. The up-conversion fluorescent marker integrated within the plastic has the advantage that the marker is never lost, and the plastic can almost always be sorted and therefore recycled. Further, regardless of the plastic packaging material being distorted / deformed or regardless of the orientation of the plastic material in the sorting machine, the integrated up-conversion fluorescent marker in the packaging material can successfully be sorted and therefore recycled. The currently available packaging plastic materials, however, may have labels attached to them instead, if anything at all, and these may fall off before reaching the sorting machine and cannot thus be detected and sorted and therefore cannot be recycled. Further, since the marker is a property of the plastic material in the packaging material according to any aspect of the present invention, there is a higher chance of the plastic material being almost always sorted even when the sorting is fast.

[0020] In particular, the up-conversion fluorescent markers according to any aspect of the present invention can be added to the plastics directly or via masterbatch route. However, due to low marker concentration in the plastics (ppm-range) the masterbatch route is clearly preferrable. The up-conversion fluorescent marker concentration in masterbatch can be in range 100 ppm - 500 ppm. More in particular, the up-conversion fluorescent marker concentration may be about 50-1000, 50-950, 50-900, 50-850, 50-800, 50-750, 50-700, 50-650, 50-600, 50-550, 50-500, 100-1000, 100-950, 100-900, 100-850, 100-800, 100-750, 100-700, 100-650, 100-600, 100-550, 100-500, 150-1000, 150-950, 150-900, 150-850, 150-800, 150-750, 150-700, 150-650, 150-600, 150-550, 150-500, 200-1000, 200-950, 200-900, 200-850, 200-800, 200-750, 200-700, 200-650, 200-600, 200-550, 200-500, 250-1000, 250-950, 250-900, 250-850, 250-800, 250-750, 250-700, 250-650, 250-600, 250-550, 250-500, 300-1000, 300-950, 300-900, 300-850, 300-800, 300-750, 300-700, 300-650, 300-600, 300-550, 300-500, 350-1000, 350-950, 350-900, 350-850, 350-800, 350-750, 350-700, 350-650, 350-600, 350-550, 350-500, 400-1000, 400-950, 400-900, 400-850, 400-800, 400-750, 400-700, 400-650, 400-600, 400-550, 400-500 ppm. Even more in particular, the up-conversion fluorescent marker concentration may be about 50, 100, 150, 200, 250, 300, 350, 400, 450, 500, 550, 600, 650, 700, 750, 800, 850, 900, or 1000 ppm in the masterbatch.

[0021] In one example, the masterbatch with 500 ppm of up-conversion fluorescent marker material can be manufactured through mixing of 50 kg of the granulated plastic material with 10 g of up-conversion fluorescent marker material and 20 ml of dispersion additive in a tumble mixer. This masterbatch can then be diluted through addition of non-marked plastics granulate in extruder.

[0022] The final concentration of up-conversion fluorescent marker in plastics may be in the range 1 ppm - 200 ppm. In particular, the final concentration of up-conversion fluorescent marker in the food-contact plastic according to any aspect of the present invention may be 1-200, 1-150, 1-100, 1-50, 1-45, 1-40, 1-35, 1-30, 1-25, 1-20, 1-15, 1-10, 1-5, 5-200, 5- 150, 5-100, 5-50, 5-45, 5-40, 5-35, 5-30, 5-25, 5-20, 5-15, 5-10, 10-200, 10-150, 10-100, 10-50, 10-45, 10-40, 10-35, 10-30, 10-25, 10-20, 10-15, 15-200, 15-150, 15-100, 15-50, 15-45, 15-40, 15-35, 15-30, 15-25, 15-20, 20-200, 20-150, 20-100, 20-50, 25-200, 25-150, 25-100, 25-50, 30-200, 30-150, 30-100, 30-50, 40-200, 40-150, 40-100, 50-200, 50-150, 50-100, 100-200, 100-150 ppm. More in particular, the final concentration of up- conversion fluorescent marker in the food-contact plastic according to any aspect of the present invention may be about 1 , 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, 100, 125, 150, 175, or 200 ppm. Even more in particular, the final concentration of up-conversion fluorescent marker in the plastic packaging material according to any aspect of the present invention may be about 10 ppm.

[0023] The homogenization of the plastics-marker mixture (i.e. plastic material with the up- conversion fluorescent marker) can be carried out in standard drum mixer. The improvement of the homogeneity of the marker distribution on the masterbatch can be achieved by use of dispersion additives, for example TEGOMER®, TEGOPREN®, TEGODISPERS®, Epolene®.

[0024] The term “fluorescent” as used herein in conjunction with up-conversion markers, refers a luminescence phenomenon in which electron de-excitation occurs almost spontaneously, and in which emission from a luminescent substance ceases when the exciting source is removed. In fluorescent materials, the excited state has the same spin as the ground state. A compound capable of fluorescence is termed a “fluor”.

[0025] The term “luminescence” as used herein refers to the process in which light is emitted from a material at a different wavelength than that which is absorbed. It is an umbrella term covering both fluorescence and phosphorescence.

[0026] As used herein, the term “up-conversion” refers to a process where light can be emitted with photon energies higher than those of the light generating the excitation. Photoexcitation at a certain wavelength in the near infrared (NIR) followed by luminescence at a shorter wavelength in the VIS is called NIR to VIS photon up- conversion. This phenomenon may be considered to be rather unusual as low energy photons are “converted” to higher energy photons. At least two NIR photons are required to generate one VIS photon. When fluorescence is emitted by a medium as a consequence of being excited with incident light, the wavelength of the fluorescence is usually longer than that of the exciting light. Photon energy is thus reduced. Up- conversion fluorescence may also occur in some cases where the wavelength of the emitted light is shorter. A more elaborate disclosure of the mechanism behind up- conversion markers is provided in EP2297678 B1. Further, photo-luminescent properties of rare earth compounds are described in US7, 184,203 which may also be used according to any aspect of the present invention.

[0027] The concept of frequency up-conversion of infrared-to-visible light in materials fixed with rare-earth (RE) was found to be efficient as a means of labelling or as markers with various functions. Examples of up-conversion markers are sodium yttrium fluoride (NaYF4) doped with lanthanide ions. Suitable lanthanide ions are the rare earths selected from cerium (Ce), erbium (Er), europium (Eu), dysprosium (Dy), gadolinium (Gd), holmium (Ho), lanthanum (La), lutetium (Lu), neodymium (Nd), praseodymium (Pr), promethium (Pm), samarium (Sm), terbium (Tb), thulium (Tm), and ytterbium (Yb). Particularly, lanthanide ions such as ytterbium (Yb3+), holmium (Ho3+), Erbium (Er3+) or Thulium (Tm3+), or Yb3+ / Er3+ co-dopants may be used.

[0028] Hexagonal sodium yttrium fluoride, NaYF4, may be specifically used for green (Yb3+ / Er3+ doped) and blue (Yb3+ / Tm3+ doped) up-conversion phosphors. Blue light can also be alternatively generated by Yb,Tm:YLF (yttrium lithium fluoride) when pumped with diode laser light having a wavelength of approximately 958 to approximately 959 nm, green visible light can be efficiently generated by Yb,Er:NYF (sodium yttrium fluoride) when pumped with diode laser light having a wavelength of approximately 976 nm, and red visible light can be efficiently generated by Yb,Er:KYF(potassium yttrium fluoride) or Yb,Er:YF3 when pumped with diode laser light having a wavelength of approximately 973.5 nm to approximately 976 nm. US6,897,999 discloses different up-conversion markers that may be used according to any aspect of the present invention.

[0029] In particular, the up-conversion fluorescent marker may be an oxide and / or salt of rare- earth metals. More in particular, the up-conversion fluorescent marker may be selected from the group consisting of yttrium oxide, yttrium ytterbium oxide, yttrium ytterbium oxysulfide, titanium dioxide, cobalt oxide, lanthanum oxide, europium oxide, coordination complexes of rare-earth metals and mixtures thereof. Examples of coordination complexes of rare-earth metals are found at least in Pointel Y et al., Inorganic Chemistry, American Chemical Society, 2020, 59 (15):10673-87 and Jakoby, M., et al., iScience 24(3) art 102207, March 19, 2021.

[0030] The term ‘end-user’ as used herein refers to the final user of the packaging material and / or the user of the packaging material that finally disposes of the packaging material into the rubbish bin. The end-user is thus the human being, or consumer that disposes of the packaging material.

[0031] The term ‘packaging material’ as used herein and as the term implies refers to material that is particularly used for packaging items. Packaging material may be of any origin that may be used to wrap and / or seal any item that needs to be packed. In particular, ‘packaging material’ refers to any material, container or wrapping, used for or in connection with the transport, handling, protection, marketing or sale of any supplies, that would particularly be used by the end-user. Packaging material may also include any material, container or wrapping used for the containment of the supplies. However, packaging material does not include the supplies in itself. Packaging materials are intended to enclose or hold together the materials that are to be packed. In other words, the material that is to be packed can be packed into or onto the packaging material. The packaging material can be a load carrier. The most important packaging materials include crates, boxes, containers, wire baskets, pallets and the like.

[0032] In particular, the packaging material may be plastic material. More in particular, the plastic material may be selected from the group consisting of Polyethylene (PE), High-Density Polyethylene (HDPE), Low-Density Polyethylene (LDPE), Linear Low Density Polyethylene (LLDPE), Polyvinylchloride (PVC), Polypropylene (PP), Polystyrene (PS), polyamide (PA), polyethylene-terephthalate (PET), Polyethylene terephthalate glycol (PETG) polymethylmethacrylate (PMMA), polycarbonate (PC), expanded polystyrene (EPS), extruded polystyrene (XPS), expanded polypropylene (EPP), polyurethanes (PU), polyvinylchloride (PVC), glass-fiber reinforced PP, epoxy-based composites, multilayersystems of above-mentioned materials and mixtures thereof. Packaging material may also include flexible packages made from films or thin sheets of polyolefins or plasticized PVC.

[0033] The first and second labels according to any aspect of the present invention may be in the form of continuously printed mark on the surface of the packaging material. The printing ink of the first and / or second labels may be removable in industrial waste washing equipment. The printing ink can contain markers and / or tracers. These markers can be fluorescent markers, which are recognizable by means of optical analytic equipment in waste sorting units. The use of different fluorescent markers with different fluorescence spectrums may enable a legend to be created wherein each fluorescent colour codes for a unique identifier that is related to the packaging material. For example, each fluorescent colour codes for a different quality of the packaging material, such as the packaging type, packaging material, packaging manufacturer, and brand behind the packed product etc. The different fluorescent colours may then be used as second label on the packaging material according to any aspect of the present invention such that the waste sorting machine can correctly sort the packaging material for recycling purposes.

[0034] The first and / or second label may be made from deinkable ink. In particular, the first and / or second labels may be printed on the surface of the packaging material by deinkable ink. The deinkable ink is selected from the group consisting of UV-curable resins, acrylic resins, methacrylic resins, polyurethane resins, ethoxy resins and mixtures thereof. The use of deinkable ink in combination with deinking as a part of deinking process will allow the removal of printing ink with all marks and reduce the probability of undesired coloration of recycled plastics. Deinking procedure takes place in washing units at basic environment (pH=12 and more) at elevated temperatures (about 60°C-80°C). The process of deinking is further explained in at least EP3932642A1. More in particular, the deinkable ink may deink at a temperature of 50°C or below or 45, 40, 35, 30°C or below. Even more in particular, the deinkable ink may be UV-curable MMA-based ink.

[0035] According to a further aspect of the present invention, there is provided method of labelling plastic packaging material, the method comprising

[0036] (a) integrating a first label on the packaging material; and

[0037] (b) integrating a second label on the packaging material, wherein the first label is readable by an end-user and the first label is visible to the enduser and distinct for packaging material that is recyclable; and wherein the second label is readable by at least one industrial waste sorting machine, wherein the second label comprises information on the material origin, type and / or use and wherein the second label is at least one up-conversion based florescent marker that is invisible to the end-user..

[0038] According to yet a further aspect of the present invention, there is provided a method of separating recyclable plastic packaging material from a mixture of recyclable plastic and non-recyclable plastic, the method comprising: contacting the mixture to at least one waste sorting machine, wherein the recyclable plastic is the plastic packaging material according to any aspect of the present invention.

[0039] In particular, the waste sorting machine is a high-speed industrial sorting machine with a high-speed optical analytics system.

[0040] The high-speed industrial sorting machine may be capable of infra-red adsorbing markerbased sorting. The combination with near infra-red analytics marker-based sorting will allow the separation of plastics waste into groups according to its application and according to its chemical composition, creating, in this way, waste streams for high- value recyclates. Examples of infra-red analytics marker-based sorting include a standard infrared sorting machine additionally equipped with marker-specific sensors, or with updated detection software, which includes marker emission spectrum in detection algorithm. More in particular, the high-speed industrial sorting machine according to any aspect of the present invention may have a conveyer band speed of 2 m / s or more. In particular, 2, 2.5, 3, 3.5, 4, 4.5, 5 m / s or more. Even more in particular, the conveyer band speed may be between 2 m / s and 5 m / s.

[0041] According to a further aspect of the present invention, there is provided a use of a double labelling system for marking plastic packaging material to be recycled, the double labelling system comprising: a first label readable by an end-user, wherein the first label is visible to the enduser and distinct for packaging material that is recyclable; and a second label readable by at least one industrial waste sorting machine, wherein the second label comprises information on the material origin, type and / or use and wherein the second label is at least one up-conversion based florescent marker that is invisible to the end-user.

[0042] In particular, plastic packaging material is selected from the group consisting of Polyethylene (PE), High-Density Polyethylene (HDPE), Low-Density Polyethylene (LDPE), Linear Low Density Polyethylene (LLDPE), Polyvinylchloride (PVC), Polypropylene (PP), Polystyrene (PS), polyamide (PA), polyethylene-terephthalate (PET), Polyethylene terephthalate glycol (PETG) polymethylmethacrylate (PMMA), polycarbonate (PC), expanded polystyrene (EPS), extruded polystyrene (XPS), expanded polypropylene (EPP), polyurethanes (PU), polyvinylchloride (PVC) and mixtures thereof.

[0043] The second label is an up-conversion based florescent marker. In particular, the first and / or second label is made from deinkable ink. EXAMPLES

[0044] The foregoing describes preferred embodiments, which, as will be understood by those skilled in the art, may be subject to variations or modifications in design, construction or operation without departing from the scope of the claims. These variations, for instance, are intended to be covered by the scope of the claims.

[0045] Example 1 (prophetic)

[0046] As example of such labelling can be considered two-layer label, the first layer is a deinkable colorless primer, the second layer contains printed signs of “Der Grune Punkt” The composition of primer corresponds to the Example 1 from WO 2021 / 165081

[0047] This primer was diluted with ethanol to a suitable viscosity (see Example 4 from WO 2021 / 165081) and applied on the surface of polypropylene film as a primer. On the top of this surface were printed signs of “Der Grune Punkt” by conventional printing inks and cured, the distance between signs was 10 cm.

[0048] After curing, only signs of “Der Grune Punkt” can be observed in visible light. The irradiation by IR-light (preferably with l=980 nm) creates irradiation in visible light of op-conversion marked, which can be detected by optical camera. The deinking process (alkaline aqueous medium, 98,7 % H2O, 1% NaOH, 0,3% of surfactant, 65°C) removes this label after 2 minutes.

Claims

CLAIMS1. Plastic packaging material, the material comprising: a first label readable by an end-user, wherein the first label is visible to the end-user and distinct for packaging material that is recyclable; and a second label readable by at least one industrial waste sorting machine, wherein the second label comprises information on the material origin, type and / or use and wherein the second label is at least one up-conversion based florescent marker that is invisible to the end-user.

2. The plastic packaging material according to claim 1, wherein the first label is an eye-catching symbol and / or word that enables the end-user to appropriately recycle the packaging material.

3. The packaging material according to either claim 1 or 2, wherein the plastic packaging material is selected from the group consisting of Polyethylene (PE), High-Density Polyethylene (HDPE), Low-Density Polyethylene (LDPE), Linear Low Density Polyethylene (LLDPE), Polyvinylchloride (PVC), Polypropylene (PP), Polystyrene (PS), polyamide (PA), polyethylene-terephthalate (PET), Polyethylene terephthalate glycol (PETG) polymethylmethacrylate (PMMA), polycarbonate (PC), expanded polystyrene (EPS), extruded polystyrene (XPS), expanded polypropylene (EPP), polyurethanes (PU), polyvinylchloride (PVC) and mixtures thereof.

4. The packaging material according to any one of the preceding claims, wherein the one up-conversion based florescent marker is integrated within the plastic packaging material.

5. The packaging material according to any one of the preceding claims, wherein the up conversion based fluorescent marker is yttrium oxide, yttrium ytterbium oxide, yttrium ytterbium oxysulfide, titanium dioxide, cobalt oxide, lanthanum oxide, europium oxide, or coordination complexes of rare-earth metals.

6. The packaging material according to any one of the preceding claims, wherein the first and / or second label is made from deinkable ink that is deinkable at a temperature of 50°C or below.

7. The packaging material according to claim 6, wherein the deinkable ink is selected from the group consisting of UV-curable resins, acrylic resins, methacrylic resins, polyurethane resins, ethoxy resins and mixtures thereof.

8. Method of labelling plastic packaging material, the method comprising(a) integrating a first label on the packaging material; and(b) integrating a second label on the packaging material, wherein the first label is readable by an end-user and the first label is visible to the end-user and distinct for packaging material that is recyclable; and wherein the second label is readable by at least one industrial waste sorting machine, wherein the second label comprises information on the material origin, type and / or use and wherein the second label is at least one up-conversion based florescent marker that is invisible to the end-user.

9. A method of separating recyclable plastic packaging material from a mixture of recyclable plastic and non-recyclable plastic, the method comprising: contacting the mixture to at least one waste sorting machine, wherein the recyclable plastic is the plastic packaging material according to any one of the claims 1 to 7.

10. The method according to claim 9, wherein the waste sorting machine is a highspeed industrial sorting machine with a conveyer band speed of 2 m / s or more and a high-speed optical analytics system.

11. The method according to any one of the claims 8 to 10, wherein the up conversion based fluorescent marker is yttrium oxide, yttrium ytterbium oxide, yttrium ytterbium oxysulfide, titanium dioxide, cobalt oxide, lanthanum oxide, europium oxide, or coordination complexes of rare-earth metals.

12. Use of a double labelling system for marking plastic packaging material to be recycled, the double labelling system comprising: a first label readable by an end-user, wherein the first label is visible to the end-user and distinct for packaging material that is recyclable; and a second label readable by at least one industrial waste sorting machine, wherein the second label comprises information on the material origin, typeand / or use and wherein the second label is at least one up-conversion based florescent marker that is invisible to the end-user. Use according to claim 12, wherein the plastic packaging material is selected from the group consisting of Polyethylene (PE), High-Density Polyethylene (HDPE),Low-Density Polyethylene (LDPE), Linear Low Density Polyethylene (LLDPE), Polyvinylchloride (PVC), Polypropylene (PP), Polystyrene (PS), polyamide (PA), polyethylene-terephthalate (PET), Polyethylene terephthalate glycol (PETG) polymethylmethacrylate (PMMA), polycarbonate (PC), expanded polystyrene (EPS), extruded polystyrene (XPS), expanded polypropylene (EPP), polyurethanes (PU), polyvinylchloride (PVC) and mixtures thereof. Use according to any one of the claims 12 to 13, wherein the up conversion based fluorescent marker is yttrium oxide, yttrium ytterbium oxide, yttrium ytterbium oxysulfide, titanium dioxide, cobalt oxide, lanthanum oxide, europium oxide, or coordination complexes of rare-earth metals.

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