WO2025190832A1

WO2025190832A1 - Delamination and/or deinking of plastic films using sulfonic acid

Info

Publication number: WO2025190832A1
Application number: PCT/EP2025/056384
Authority: WO
Inventors: Steven DE MEESTER; Sibel ÜGDÜLER; Tobias DE SOMER; Martijn ROOSEN
Original assignee: Universiteit Gent
Current assignee: Universiteit Gent
Priority date: 2024-03-11
Filing date: 2025-03-10
Publication date: 2025-09-18
Anticipated expiration: 2026-09-11

Abstract

The invention relates to a method for deinking and/or delaminating a plastic material. The plastic material comprises a monolayered structure or a multilayered structure, The method comprises the step of contacting the plastic material with sulfonic acid of formula R=(SO)₂-OH or with a mixture comprising at least 25 vol% of sulfonic acid of formula R=(SO)₂-OH, with R comprising a C1-C10 alkyl or an aryl, with the alkyl or aryl being substituted or non-substituted.

Description

Delamination and/or deinking of plastic films using sulfonic acid

Field of the invention

[0001] The present invention relates to plastic recycling, more particularly to a method to deink and/or to delaminate plastic material such as plastic films.

Background art

[0002] The demand for plastic packaging materials continues to grow significantly due to their exceptional functional performance, including among others, oxygen, moisture and light barrier, printability and food compliance. However, recycling rates of plastic packaging are still low due to the lack of infrastructure in collection and sorting, as well as their inherently complex structures including the presence of multilayers, additives, inks, among others.

[0003] In European countries, plastic packaging, for instance from post-consumer waste, is currently recovered through open-loop mechanical recycling processes. However, contamination from both the production and use phase impedes re-use of these recycled plastics in high-value applications. For example, the presence of ink adversely affects the optical and physicochemical properties of recycled plastic films. In addition, a mix of inks results in dark-colored pellets after extrusion, thus making the recovered plastic films suitable only for ‘downcycled’ products. Furthermore, plastic packaging generally consists of a combination of different types of polymers, each with their own specific functionality in order to obtain superior preservation performances tailored to their specific purpose. Differences in the processing properties of the different polymer layers impedes recycling of multilayer plastic films as they cause incompatibility issues during mechanical recycling. Therefore, delamination and/or deinking methods should be further developed to ensure the recycling of plastic such as plastic films, in particular plastic or plastic films provided with inks and/or plastic or plastic films comprising different polymer layers.

[0004] Several deinking processes are available. For instance, EP2832459 B1 describes a deinking technology for monolayer plastic films, which removes inks from different type of plastics through a surfactant-based system. In this process, printed plastic films pass through several treatments, including e.g. grinding, deinking, washing, drying, and pelletizing in order to obtain ink- free plastic films. Also, ionic or non-ionic surfactants can be used to remove water-based inks from plastic films. In EP1419829 A1 , non-ionic surfactants were used together with organic solvents in order to obtain high deinking efficiencies. However, it has been stated that after the treatment, physico-mechanical properties of recycled film decreases substantially compared to virgin material. [0005] In the patented process known as the Nordenia Extraction and Cleaning process or NorEC (DE19651571A1), ethyl acetate was used as a solvent-based extraction medium to remove a broad range of inks. All these deinking procedures are only suitable to deink plastic material having the ink layer at the outer surface. However, a post-consumer waste stream typically consists of a mix of monolayer and multilayer films where the ink is between two layers. The above-described treatments are unable to deink multilayer plastic films since the deinking mixtures cannot reach the ink. Therefore, a prior delamination is required for multilayer packaging to achieve deinking.

[0006] Delamination of multilayer structures can be achieved through different physicochemical routes such as selective dissolution/degradation of constituent polymer layers or tie layers. For example, APK owns a delamination process called Newcycling® where PA/PE multilayer films are separated via selective PE dissolution at industrial scale. In terms of dissolution of tie layers for delamination of multilayer structures, Saperatec GmbH (Germany) uses a micro-emulsion comprising swelling agents, carboxylic acids, water, and surfactants for delamination of multilayer packaging containing aluminium.

[0007] Alternatively, acids are also used as a delamination medium for multilayer structures. For example, in W02003/104315 A1 protonic carboxylic acids such as acetic acid are mixed with organic solvents for the separation of polymer, aluminium and/or paper from multilayer films. Similarly, in CN101165084A recycling of composite packaging waste is carried out in a continuous industrial scale through delamination of Al from PE delamination using formic acid and nitric acid. None of these delamination technologies is used in combination with deinking.

[0008] WO2021/198737 describes a method to deink plastic using an oxidizing inorganic acid and a short or medium chain fatty acid.

Summary of the invention

[0009] It is an object of the present invention to provide a method to recycle plastic material, in particular to provide a method to deink plastic material, to delaminate plastic material or to deink and delaminate plastic material.

[0010] It is an object of the present invention to provide a method to deink, to delaminate or to deink and delaminate plastic waste and/or plastic films.

[0011] It is another object of the present invention to provide a method to deink a plastic material comprising a monolayered structure comprising a polymer layer comprising or being provided with at least one ink.

[0012] It is a further object of the present invention to provide a method to delaminate a plastic material comprising a multilayered structure comprising at least two polymer layers, whereby the multilayered structure or one or more polymer layer of the multilayered structure can comprise or be provided with at least one ink.

[0013] It is a further object of the present invention to provide a method that allows to deink and to delaminate plastic material comprising multilayered structures, whereby the multilayered structure or one or more polymer layers of the multilayered structure is provided with at least one ink, for example plastic waste and/or plastic films, in a single step.

[0014] It is still a further object of the present invention to provide a method that allows to deink or to deink and delaminate a wide variety of plastic material having different types of inks and/or including different types of plastic films having a multilayered structure, plastic material having ink on an outer surface as well as plastic material having ink covered by one or more layers, for example one or more polymer layers or one or more coating layers.

[0015] It is a further object of the present invention to provide a method to deink, a method to delaminate or a method to deink and delaminate plastic material without causing neither dissolution nor degradation of the main plastic components of the polymer material.

[0016] It is a further object of the present invention to provide a method that allows removing any type of inks from plastic material such as solvent-based inks, water-based inks and UV-based inks, either from monolayer or from multilayer plastic material.

[0017] It is a further object of the present invention to provide a method to deink polymer material having ink either at the outer surface the polymer material or not at the outer surface of the polymer material, for example between two layers, for example between to polymer layers or covered with a coating layer.

[0018] It is a further object of the present invention to provide an economic viable method to deink plastic material or to delaminate and deink plastic material, in particular plastic waste.

[0019] According to a first aspect of the present invention a method for deinking and/or delaminating a plastic material is provided. The plastic material comprises a monolayered structure or a multilayered structure. In case the plastic material comprises a monolayered structure, such structure comprises one polymer layer comprising or being provided with at least one ink. In case the plastic material comprises a multilayered structure, such structure comprises at least two polymer layers, whereby the multilayered structure or one or more polymer layer optionally comprises or is optionally provided with at least one ink, The method comprises the step of contacting the plastic material with sulfonic acid of formula R=(SO)2-OH or with a mixture comprising at least 25 vol% of sulfonic acid of formula R=(SO)2-OH, with R comprising a CICI 0 alkyl or an aryl, with the alkyl or aryl being substituted or non-substituted.

[0020] The method according to the present invention allows to obtain deinking and/or delamination. In preferred embodiments, the method according to the present invention allows to obtain simultaneously deinking and delamination of plastics, i.e. to obtain deinking and delamination in a single process step.

Sulfonic acid

[0021] Sulfonic acid (or sulphonic acid) refers to a group of organosulfur compounds with the general formula R-S(=O)2-OH, where R is an alkyl or aryl group and the S(=O)2(OH) group a sulfonyl hydroxide.

[0022] In case R comprises an alkyl, the alkyl is preferably a C1-C10 alkyl and more preferably a C1-C4 alkyl. The alkyl may be substituted or non-substituted. Preferred substituents comprise one or more hydroxyl, one or more halogen such as F, Cl or Br or one or more amine group. [0023] In case R comprises an aryl, any functional group or substituent derived from an aromatic ring, usually an aromatic hydrocarbon, can be considered. Preferred aryl groups comprise phenyl (C6H5-), tolyl (CH3C6H4-), xylyl ((CHs^CeHs-) or naphthyl (C10H7-). The aryl group may be substituted or non-substituted. Preferred substituents comprise one or more hydroxyl, one or more halogen such as F, Cl or Br, or one or more amine group.

[0024] Preferred sulfonic acids comprise methanesulfonic acid (MSA), ethanesulfonic acid, propane sulfonic acid, trifluoromethanesulfonic acid (TFMSA), benzenesulfonic acid (BSA), substituted benzenesulfonic acid as for example 4-dodecylbenzenesulfonic acid (4-DBSA), p-toluenesulfonic acid (PTSA), 4-biphenylsulfonic acid, 2-naphtalenesulfonic acid (2-NSA), 1-naphthol-4-sulfonic acid, 4-aminobenzenesulfonic acid, 2-amino-1 -naphthalenesulfonic acid, 2- aminoethanesulfonic acid and 4-hydroxybenzenesulfonic acid.

[0025] Sulfonic acids are strong acids. They are stronger acids than other organic acids, such as formic acid and acetic acid. In fact, their acid strength is comparable with that of strong mineral acids such as H2SO4, HCI and HNO3. They have high solubility towards metal salts and carbohydrate polymers such as cellulose which are generally used as an adhesive/ink resin in plastics.

[0026] Sulfonic acids are readily biodegradable and has low corrosivity and vapour pressure, which increases the economic and environmental feasibility of a method using sulfonic acids for scale up purposes.

[0027] Due to their high chemical and thermal stability, sulfonic acids can be mixed with oxidizing and reducing agents for example to allow simultaneous removal of metal salts, cross-linked adhesives and/or inks.

[0028] In particular embodiments the method according to the present invention comprises contacting the plastic material with pure sulfonic acid of formula R=(SO)2-OH, for example with methanesulfonic acid (MSA), ethanesulfonic acid, propane sulfonic acid, trifluoromethanesulfonic acid (TFMSA), benzenesulfonic acid (BSA), substituted benzenesulfonic acid as for example 4- dodecylbenzenesulfonic acid (4-DBSA), p-toluenesulfonic acid (PTSA), 4-biphenylsulfonic acid, 2- naphtalenesulfonic acid (2-NSA), 1-naphthol-4-sulfonic acid, 4-aminobenzenesulfonic acid, 2- amino-1 -naphthalenesulfonic acid, 2-aminoethanesulfonic acid and 4-hydroxybenzenesulfonic acid.

[0029] In other embodiments, the method according to the present invention comprises contacting the plastic material with a mixture comprising sulfonic acid. Preferably, the mixture comprises at least 25 vol% of a sulfonic acid as specified above. In case the mixture comprises more than one sulfonic acid, the total amount of sulfonic acids is at least 25 vol%. More preferably, the mixture comprises between 25 and 95 vol% sulfonic acid, for example between 25 and 90 vol%, such as 30 vol%, 40 vol%, 50 vol%, 60 vol%, 70 vol% or 80 vol%. [0030] The mixture comprising the sulfonic acid may further comprise other compounds. In particular embodiments the mixture comprising the sulfonic acid further comprises one or more hydrocarbons, one or more oxidizing agents or a combination of one or more hydrocarbons and one or more oxidizing agents. a) Mixture comprising sulfonic acid and one or more hydrocarbons

[0031] In preferred embodiments, the mixture comprising the sulfonic acid comprises the addition of one or more hydrocarbons such as hexane, octane or cyclohexane. The addition of one or more hydrocarbon to the mixture comprising the sulfonic acid allows the swelling of the plastic material, for example the swelling of polyolefins. By adding one or more hydrocarbons to the mixture, the rate of delamination is increased.

[0032] In case the mixture comprises hydrocarbons, the mixture comprises preferably at least 25 vol% sulfonic acid and at least 10 vol% hydrocarbons. The mixture comprises for example at least 25 vol% sulfonic acid and at least 10 vol% alkane such as hexane or octane. In an alternative embodiment the mixture comprises at least 25 vol% sulfonic acid and at least 10 vol% cycloalkane such as cyclohexane.

In case the mixture comprises more than one sulfonic acid, the total amount of sulfonic acid is at least 25 vol%. In case the mixture comprises more than one hydrocarbon, the total amount of hydrocarbons is at least 10 vol%.

[0033] More preferably a mixture comprising sulfonic acid comprises between 25 vol% and 90 vol% sulfonic acid and between 10 and 75 vol% hydrocarbons.

[0034] The term ‘hydrocarbon’ refers to organic compounds comprising mainly carbon and hydrogen. Preferred hydrocarbons consist entirely of carbon and hydrogen and do not comprise heteroatoms such as oxygen. Hydrocarbons can be saturated or non-saturated. Saturated hydrocarbons are however preferred.

[0035] Preferred hydrocarbons comprise at least 5 carbon atoms. The at least one (saturated) hydrocarbon present in the mixture has preferably maximum 12 carbon atoms. More preferably, the at least one (saturated) hydrocarbon has 10 carbon atoms, 8 carbon atoms, 6 carbon atoms or 5 carbon atoms.

[0036] Apolar hydrocarbons are preferred as they do not react with other compounds present in the mixture, for example with the sulfonic acid, allowing recovery with high purity and lower cost compared to other methods using compounds that may create azeotropic mixtures.

[0037] Preferred hydrocarbons comprise saturated hydrocarbons. Saturated hydrocarbons are apolar. They comprise acyclic hydrocarbons (including linear hydrocarbons and branched hydrocarbons) and cyclic hydrocarbons. Acyclic alkanes are also referred to as alkanes and cyclic alkanes are referred to as cycloalkanes.

[0038] In the method according to the present invention cycloalkanes are preferred over alkanes because of their high diffusion rate through (apolar) polymer layers as for example through polypropylene or polyethylene polymer layers. [0039] Alkanes may have a linear or branched carbon chain. All carbon atoms in the structure of an alkane are sp³ hybridized. The melting point and boiling point of an alkane is related to the length of the carbon chain. The longer the carbon chain, the higher the melting or boiling point. At standard temperatures, alkanes containing up to four carbon atoms are gases, and those containing 5 to 17 carbon atoms are liquids.

[0040] For the method according to the present invention alkanes having 5 to 12 carbon atoms including all their isomers and stereoisomers, are preferred. Particularly preferred alkanes comprise hexane, heptane and octane including all their isomers and stereoisomers.

[0041] Isomers of hexane comprise n-hexane, 2-methyl pentane, 3-methyl pentane, 2,2-dimethyl butane and 2,3-dimethyl butane.

Isomers of heptane comprise n-heptane, 2-methylhexane, 3-methylhexane, 2,2-dimethylpentane, 2,3-dimethylpentane, 2,4-dimethylpentane, 3-3-dimethylpentane, 3-ethyl-pentane and 2,2,3- tri methylbutane.

Isomers of octane comprise n-octane, 2-methylheptane, 2-methylheptane, 3-methylheptane (including 2 enantiomers), 4-methylheptane, 3-ethylhexane, 2,2-dimethylhexane, 2,3- dimethylhexane (including 2 enantiomers), 2,4-dimethylhexane (including 2 enantiomers), 2,5- dimethylhexane, 3,3-dimethylhexane, 3,4-dimethylhexane (including 2 enantiomers and 1 meso compound), 3-ethyl-2-methylpentane, 3-ethyl-3-methylpentane, 2,2,3-trimethylpentane (including 2 enantiomers), 2,2,4-trimethylpentane, 2,3,3-trimethylpentane, 2,3,4-trimethylpentane and 2, 2,3,3- tetramethylbutane.

[0042] Cycloalkanes comprise a ring-shaped structure of sp³ hybridized carbon atoms. Cycloalkanes comprise monocyclic alkanes (comprising one ring structure), either substituted or non-substituted and polycyclic alkanes (comprising more than one ring structure), for example bicyclic alkanes (comprising two ring structures), either substituted or non-substituted.

[0043] The number of rings in a cycloalkane is defined as the minimum number of bonds that must be broken in order to convert the molecule in an open-chain fragment.

[0044] For the method according to the present invention cycloalkanes having 5 to 12 carbon atoms are preferred. In particular cycloalkanes having a ring of 5 to 12 carbon atoms are preferred. Examples of cycloalkanes comprise cyclopentane, cyclohexane, cycloheptane or cyclooctane, either substituted or non-substituted.

[0045] For the method according to the present invention cycloalkanes having a boiling point higher than 70 °C are preferred.

[0046] Examples of monocyclic alkanes comprise substituted cyclobutane, for example methylcyclobutane, ethyl-cyclobutane, ethylmethyl-cyclobutane, dimethyl-cyclobutane, diethylcyclobutane; cyclopentane either substituted or non-substituted, for example cyclopentane, methylcyclopentane, ethyl-cyclopentane, methylethyl-cyclopentane, dimethyl-cyclopentane, diethylcyclopentane; cyclohexane, either substituted or non-substituted, for example cyclohexane, methylcyclohexane, ethyl-cyclohexane, methylethyl-cyclohexane, dimethyl-cyclohexane, diethylcyclohexane. [0047] Examples of bicyclic alkanes comprise for example bicyclo[2.2.0]hexane, bicyclo[2.1 .1]hexane, bicyclo[2.2.1]heptane, bicyclo[4.4.0]decane and bicyclo[4.3.1]decane. b) Mixture comprising sulfonic acid and one or more oxidizing agents

[0048] In preferred embodiments, the mixture comprising the sulfonic acid comprises the addition of one or more oxidizing agent.

[0049] The term ‘oxidizing agent’ refers to a compound acting as an electron acceptor in redox chemical reactions by gaining electrons from a reducing agent which donates electrons. Common oxidizing agents are oxygen, peroxides, peroxy acids, hydrogen peroxide, some inorganic acids and the halogens.

[0050] Since sulfonic acids are chemically resistant towards oxidants, they can be mixed with oxidizing agents such as hydrogen peroxide, inorganic acids such as sulfuric acid, ozone, hypochloride and nitrous oxide in order to increase the reaction rate of hetero polymers used as an adhesive or an ink component.

[0051] In case the mixture comprises one or more oxidizing agent, the mixture comprises preferably at least 25 vol% sulfonic acid and at least 10 vol% oxidizing agent. In case the mixture comprises more than one sulfonic acid, the total amount of sulfonic acid is at least 25 vol%. In case the mixture comprises more than one oxidizing agent, the total amount of oxidizing agents is at least 10 vol%.

[0052] More preferably, the mixture comprising sulfonic acid comprises between 50 vol% and 90 vol% sulfonic acid and between 10 and 50 vol% oxidizing agent. c) Mixture comprising sulfonic acid, one or more hydrocarbons and one or more oxidizing agents

[0053] In preferred embodiments, the mixture comprising the sulfonic acid comprises the addition of one or more hydrocarbon and one or more oxidizing agent. The above described hydrocarbons and oxidizing agents can be considered.

[0054] In case the mixture comprises one or more hydrocarbon and or one or more oxidizing agent, the mixture comprises preferably at least 25 vol% sulfonic acid, at least 10 vol% hydrocarbons and at least 10 vol% oxidizing agent. In case the mixture comprises more than one sulfonic acid, the total amount of sulfonic acid is at least 25 vol%. In case the mixture comprises more than one hydrocarbon, the total amount of hydrocarbons is at least 10 vol%. In case the mixture comprises more than one oxidizing agent, the total amount of oxidizing agents is at least 10 vol%.

[0055] Preferred mixtures comprise methane sulfonic acid, cyclohexane and hydrogen peroxide or benzene sulfonic acid, cyclohexane and hydrogen peroxide.

Plastic material

[0056] The plastic material to be used in the method of the present invention comprises a monolayered structure or a multilayered structure. In case the plastic material comprises a monolayered structure, the plastic material comprises (exactly) one polymer layer, whereby the polymer layer comprises or is provided with at least one ink. In case the plastic material comprises a multilayered structure, the plastic material comprises at least two polymer layers, for example 2, 3, 4, 5 ,6 ,8 or 10 polymer layers. The multilayered structure or one or more polymer layer optionally comprises or is optionally provided with at least one ink.

[0057] A polymer layer of a monolayered or multilayered structure comprises preferably a polymer selected from the group consisting of polyolefins (such as polyethylene (PE), including low-density polyethylene (LDPE) and high-density polyethylene (HDPE), and polypropylene (PP)), polyethylene terephthalate (PET), polyurethanes (PU), polyamides (PA), polystyrenes (PS), polycarbonates (PC), ethyl vinyl alcohols (EVOH), ethylene vinyl acetates (EVA), polyvinyl chlorides (PVC), and copolymers thereof. Particularly preferred polymer layers comprise polyolefins such as polyethylene (PE), including low-density polyethylene (LDPE) and high-density polyethylene (HDPE), and polypropylene (PP)) or polyethylene terephthalate (PET).

[0058] The plastic material or plastic film or in particular a polymer layer of a monolayered or multilayered structure is preferably not reinforced with fibres or not reinforced with a fabric, for example not reinforced with glass fibres or a fabric comprising glass fibres either epoxidized or not. [0059] A polymer layer of a monolayered or multilayered structure preferably does not comprise a silicone layer or coating.

[0060] A polymer layer typically has a thickness ranging between 3 pm and 300 pm, for example ranging between 10 pm and 250 pm or between 20 pm and 150 pm, such as 30 pm, 50 pm, 70 pm or 100 pm.

[0061] A monolayered structure typically has a thickness ranging between 3 pm and 300 pm, for example ranging between 10 pm and 250 pm or between 25 pm and 85 pm, such as 30 pm, 50 pm, 70 pm or 80 pm.

[0062] A multilayered structure typically has a thickness of at least 10 pm, for example ranging between 10 and 500 pm, preferably between 20 pm and 250 pm or between 50 pm and 200 pm, such as 70 pm, 80 pm, 100 pm or 150 pm.

[0063] The plastic material to be used in the method of the present invention can be any plastic material including plastic packaging, plastic bags, plastic labels, comprising a monolayered structure comprising one polymer layer or a multilayered structure comprising at least two polymer layers, for example 4, 5, 6, 7, 8 or 10 polymer layers. The term plastic material also encompasses plastic waste. Plastic waste may comprise post-industrial plastic waste and post-consumer plastic waste. Post-industrial plastic waste includes plastic material that is used or produced in a manufacturing process and comprises for example plastic films such as stretch films. Post-industrial plastic waste usually comprises homogeneous material, composed of a single polymer type or of a limited number of polymer types and is usually clean. Post-consumer plastic waste includes plastic material that has already been used by the end user and comprises for example bottles, trays, plastic packaging and household items. Post-consumer plastic waste usually comprises a mixture of different polymer materials and may be highly contaminated and dirty. The polymer material possibly suffered from degradation during service life. Plastic material encompasses for example waste flows comprising polyolefin based material such as polyethylene (PE) or polypropylene (PP), either rigid or non-rigid (films), such waste flows are sometimes referred to as DKR 310 (plastic films), DKR 321 (polyolefin plastic bottles), DKR 323 (mixed polyolefin items), DKR 323-2 (flexible polyolefin items), DKR 324 (polypropylene) and DKR 329 (polyethylene).

[0064] In preferred embodiments, the plastic material comprises a plastic film. As used herein, a “plastic film” refers to a continuous polymeric material, which is typically non-rigid or flexible, and usually thin. A plastic film may comprise a monolayered structure comprising one polymer layer or a multilayered structure comprising at least two polymer layers.

A plastic film typically has a thickness ranging between 3 pm and 300 pm, for example between 10 pm and 250 pm.

[0065] The plastic material, plastic film or polymer layer of a monolayered or multilayered structure may be composed of one type of polymeric material or may be a blend of two or more types of polymeric materials. In particular a polymer layer of a plastic material or plastic film may be composed of one type of polymeric material or may be a blend of two or more types of polymeric materials. An important advantage of the method of the invention is that it can be used with different types of plastic materials, or combinations of plastic materials. In embodiments, the plastic material or plastic film, comprises one or more polymers selected from the group comprising or consisting of a polyolefin (such as polyethylene (PE), including low-density polyethylene (LDPE) and high- density polyethylene (HDPE), and polypropylene (PP)), polyethylene terephthalate (PET), polyurethane (PU), a polyamide (PA), a polystyrene (PS), a polycarbonate (PC), ethyl vinyl alcohol (EVOH), ethylene vinyl acetate (EVA), polyvinyl chloride (PVC), and copolymers thereof, preferably a polyolefin and/or PET.

[0066] In addition to the polymeric material, the plastic material, plastic film or a polymer layer or layers of the plastic material or plastic film may comprise contaminants and/or dirt.

“Contaminants” as used herein, refer to components of the plastic material that are not part of the polymeric structure. Contaminants include, for example, but without limitation, additives, coatings such as barrier coatings, metal coatings or biocoatings, adhesives (e.g. glue), inks and labels such as plastic labels or paper labels. As used herein, “dirt” refers to impurities that adhere to the plastic material, or plastic film, during their life cycle such as dust, soil, grease, organic waste, etc.

In certain embodiments, the plastic material, plastic film or one or more layers of a plastic material or plastic film comprises a metal material such as aluminium or an aluminium alloy, for example an aluminium or aluminium alloy layer.

In further embodiments, the plastic material, plastic film or one or more layers of a plastic material or plastic film may comprise a paper or cardboard layer.

Furthermore, in certain embodiments, the plastic material, plastic film or one or more polymer layers of a plastic material or plastic film comprises or is provided with at least one ink. The ink, coating and/or adhesive layer that may be present in the plastic materials described herein can be composed of various types of polymers such as, without limitation, polyurethane, nitrocellulose, cellulose acetate propionate, cellulose acetate butyrate, cellulose acetate, methyl methacrylate/butyl methacrylate copolymer, polyvinyl butyral, poly(methyl methacrylate), poly(n- butyl methacrylate), hydroxyl containing copolymer of vinyl chloride and acid esters, polyvinyl acetate, acrylic polymers, etc.

It is clear that the plastic material, plastic film or one or more layers of the plastic material or plastic film may comprise multiple contaminants and/or dirt, for example additives, barrier coatings, adhesives, one or more metal layers and/or one or more paper or cardboard layers.

[0067] As mentioned above, the plastic material or plastic film, may have a monolayered structure comprising one polymer layer or may have a multilayered structure comprising at least two polymer layers.

[0068] In case the plastic material or plastic film comprises a monolayered structure, such structure comprises one polymer layer comprising or provided with at least one ink. Ink may be provided on an outer surface of the plastic material or plastic film, for example on the outer surface of the polymer layer of the plastic material or plastic film. Alternatively, the ink may be covered by one or more layers, for example one or more coating layers. Ink can also be embedded in a polymer layer, such as a polymer based layer, a varnish, or barrier layer.

The ink can be applied on the plastic material, for example on a polymer layer, by any technique known in the art, for example a printing technique.

[0069] The main ingredients of inks are pigments, dyes, solvents, binders and additives, for example surfactants and/or solubilizers. Pigments (organic or inorganic) or dyes give color and opacity to the ink and may influence the fluidity of the ink. Binders, usually low-molecular-weight polymeric resins, disperse the pigments and retain them on the plastic surface after printing. The solvent is a liquid, providing fluidity and allowing the transfer of the ink from the printing system to the substrate. Additives in the ink may for example comprise waxes, surfactants, drying agents and antioxidizing agents.

[0070] A monolayered structure, for example the polymer layer of the monolayered structure may further comprise contaminants and/or dirt. The polymer layer can for example be provided with one or more additives, with one or more coatings such as barrier coatings, with one or more adhesives, with one or more metal layer and/or with one or more paper or cardboard layers.

[0071] The plastic material or plastic film may not only comprise a monolayered structure but also a multilayered structure. A multilayered structure or multilayered plastic material or plastic film refers to a structure, a material or a film comprising at least two polymer layers, for example 4, 5, 6, 8 or 10 polymer layers, configured in an (alternating) arrangement to form a laminate structure. In particular embodiments, a multilayered structure comprises at least two polymer layers, for example 4, 5, 6, 8 or 10 polymer layers, each polymer layer independently comprising one or more polymers selected from the group comprising or consisting of a polyolefin (such as polyethylene (PE), including low-density polyethylene (LDPE) and high-density polyethylene (HDPE), and polypropylene (PP)), polyethylene terephthalate (PET), polyurethane (PU), polyamide (PA), polystyrene (PS), polycarbonate (PC), ethyl vinyl alcohol (EVOH), ethylene vinyl acetate (EVA), polyvinyl chloride (PVC), and copolymers thereof, preferably a polyolefin and/or PET. The multiple polymer layers may be adhered to one another by means of an adhesive layer, e.g. a glue.

[0072] The two or more plastic layers may be the same or distinct from each other. For example, a multilayered plastic material or plastic film may comprise two PE layers, or a PET layer and a PE layer. In certain embodiments, a multilayer plastic material is used comprising at least two different polymer layers. A multilayered plastic material or plastic film may further comprise a non-plastic layer such as a metal or metallised layer (e.g. an aluminium layer), or a coating layer (e.g. a varnish). For example, a multilayer plastic material or plastic film may comprise a PET layer and a PE layer, and an Al layer between these polymer layers.

[0073] Preferred multilayered structure comprise or are provided with at least one ink. In case the multilayered structure comprises or is provided with at least one ink, such ink may be provided on an outer surface of the plastic material or plastic film, for example on the outer surface of a polymer film. Alternatively, the ink may be covered by one or more layers. For example, ink may be provided between two polymer layers of a multilayered structure, or between a polymer layer and a coating. Ink can also be embedded in a layer, such as a polymer based layer, a varnish, or barrier layer. The ink can be applied on the plastic material by any technique known in the art, for example a printing technique.

[0074] The main ingredients of inks are pigments, dyes, solvents, binders and additives, for example surfactants and/or solubilizers. Pigments (organic or inorganic) or dyes give color and opacity to the ink and may influence the fluidity of the ink. Binders, usually low-molecular-weight polymeric resins, disperse the pigments and retain them on the plastic surface after printing. The solvent is a liquid, providing fluidity and allowing the transfer of the ink from the printing system to the substrate. Additives in the ink may for example comprise waxes, surfactants, drying agents and antioxidizing agents.

[0075] A multilayered structure or one or more polymer layers of such multilayered structure may further comprise contaminants and/or dirt. The multilayered structure or one or more polymer layers of the multilayered structure can for example be provided with one or more additives, with one or more coatings such as barrier coatings, with one or more adhesives, with one or more metal layer and/or with one or more paper or cardboard layers.

[0076] An important advantage of the method according to the present invention is that it allows to deink plastic material comprising or provided with different types of inks, for example with solventbased inks, water-based inks, offset inks, UV and/or EB curable inks and any combination thereof. The inks can be cross-linked. Non-limiting examples of solvent-based inks include inks comprising nitrocellulose based resins, polyurethane based resins, polyvinylchloride based resins, ethyl cellulose based resins, cellulose acetate propionate based resins, cellulose acetate butyrate based resins, polyvinyl butyral based resins, polyacrylate based resins, polyamide based resins, and combinations thereof. Non-limiting examples of water-based inks include inks comprising acrylate based resins, maleics based resins or combinations thereof. Non-limiting examples of offset inks include modified rosin resins, in particular phenolic modified rosin resins, alkyd based resins and combinations thereof. Non-limiting examples of ultraviolet curable (UV) and/or electron beam (EB) curable inks include acrylate based resins, for example epoxy acrylate based resins. The plastic material may be provided with or comprise one type of ink or a a combination of different types of inks.

Contacting step

[0077] For an efficient deinking and delamination process, it is of importance that the plastic material is in mutual contact with the sulfonic acid or with the mixture comprising the sulfonic acid. Therefore, in the method of the present invention, the plastic material is contacted with the sulfonic acid or the mixture comprising the sulfonic acid to form a mixture comprising the sulfonic acid and the plastic material. While the contacting proceeds, at least partially deinked and/or delaminated plastic material, as well as ink, glue and/or other components dissolved or liberated from the deinked and/or delaminated plastic material will be present in the mixture comprising the sulfonic acid and the plastic material as well.

[0078] The contacting may be carried out e.g. by immersing the plastic material in the sulfonic acid or in the mixture comprising the sulfonic acid. For example, the plastic material may be introduced in a container and the sulfonic acid or the mixture comprising the sulfonic acid may be added, or the plastic material may be introduced in a container wherein the sulfonic acid or the mixture comprising the sulfonic acid was previously introduced.

[0079] It has been found that friction between the plastic films may promote deinking. Preferably, the plastic material and the sulfonic acid or the mixture comprising the sulfonic acid are contacted in amounts so that the volume of the plastic material over the total volume of the sulfonic acid or the total volume of the mixture comprising the sulfonic acid is ranging from at least 0.01 to at most 10.00, more preferably from at least 0.05 to at most 7.00, from at least 0.10 to at most 5.00, or from at least 0.50 to at most 2.50, even more preferably from at least 0.80 to at most 1 .20.

[0080] It has been found that higher temperatures during the contacting step may favour an efficient deinking and delamination process, however the temperature is limited by the melting point of the plastic material. It is clear that the temperature should be lower than the melting temperature of the plastic material. Therefore, the contacting step is carried out at a temperature below 100°C. [0081] In embodiments, the plastic material is contacted with the sulfonic acid or with the mixture comprising the sulfonic acid a temperature below the melting point of the lowest melting polymer in the plastic material, preferably at least 2 °C, more preferably at least 5 °C, even more preferably at least 10 °C, below the melting point of the lowest melting polymer in the plastic material. In embodiments, the plastic material is contacted with the sulfonic acid or with the mixture comprising the sulfonic acid at a temperature of at least 50°C such as at least 60°C, 70°C, 75°C, 80°C or 85°C. In embodiments, the plastic material is contacted with the sulfonic acid or the mixture comprising the sulfonic acid at a temperature between 50°C and 100°C such as between 55°C and 100°C, between 60°C and 100°C, between 65°C and 100°C or between 70°C and 100°C, preferably between 50°C and 90°C such as between 55°C and 90°C, between 60°C and 90°C, between 65°C and 90°C or between 70°C and 90°C.

[0082] In some embodiments, when contacting the plastic material with sulfonic acid or with the mixture comprising sulfonic acid, the turbulence of the resulting mixture (comprising the plastic material and sulfonic acid, or the plastic material and the mixture comprising sulfonic acid) has a Reynolds number (Re) above 3500, for example, above 4000 Re. Such turbulency is in particular required in case large amount of plastic material are use.

[0083] In embodiments, the method further comprises mechanically agitating the sulfonic acid or the mixture comprising the sulfonic acid while the plastic material is contacted with the sulfonic acid or the mixture comprising the sulfonic acid. These treatments advantageously increase the efficiency of the deinking and delamination method, or decrease the contact time needed. In certain embodiments, the mechanical agitation such as the stirring, is continued as long as the plastic material is contacted with the sulfonic acid or the mixture comprising the sulfonic acid. Mechanical agitation can be applied by any method known in the art. For example, the mixture may be stirred (e.g. by using magnetic stirrer, by stirring in a continuous stirred tank reactor (CSTR) using a rotating agitator), mixed, or (high-intensity) sonication may be applied. In particular embodiments, the plastic material is contacted with the sulfonic acid or the mixture comprising the sulfonic acid under stirring, preferably the plastic material is contacted with the sulfonic acid or the mixture comprising the sulfonic acid under stirring at 300 rpm or more, more preferably at 500 rpm or more by creating high turbulence in the media.

[0084] As noted above, temperature, mechanical agitation of the mixture, volume ratio of the sulfonic acid or the mixture comprising the sulfonic acid may influence the efficiency of the deinking and/or delaminating method and as such determine the contact time needed to achieve deinking and/or delamination. For the purposes of the present invention, more efficient deinking and/or delamination refers to either faster deinking and/or delamination and/or obtaining a higher degree of deinking and/or delamination. Further, the contact time may be determined by the type of ink, e.g. water- and solvent-based inks requiring shorter contact times than UV-based inks. In some embodiments, the plastic material is contacted with the sulfonic acid or the mixture comprising the sulfonic acid for a suitable period of time, for instance for at least 5, 10, 15 or 30 minutes or for at least 1 hour and/or for less than 4 hours, for less than 2 hours or for less than 1 .5 hours such as for about 1 hour or less.

Pre-treatment step(s)

[0085] Using smaller sizes of plastic material may result in faster and more efficient deinking and/or delamination due to higher diffusion rates. Therefore, in certain embodiments, the method may comprise an additional step of reducing the size of the plastic material before the contacting step. Too small sizes on the other hand may become unpractical. In particular embodiments, the plastic material may be reduced in size to obtain plastic material having a sieve diameter between 0.01 cm and 20.00 cm, for example between 0.01 cm and 10.00 cm, between 0.10 cm and 10.0 cm or between 0.10 cm and 4.00 cm, preferably between 0.50 cm and 4.00 cm. The term ‘sieve diameter’ refers to the size of a sieve opening (the width of a square aperture) through which a particle will pass. Techniques for reducing the size of a plastic material are well-known to the skilled person and may include, for example, cutting, shredding, milling and/or grinding.

[0086] The plastic material, in particular plastic waste, may also or further be subjected to one or more other pre-treatment steps before the contacting step. For example, paper or cardboard may be removed from the plastic material, and/or the plastic material may be sorted. Polymer sorting techniques include, for example, wind shifting, density separation and/or near infra-red (NIR) separation, and as known to the skilled person. Plastic material can be prewashed with water and/or water containing detergent to remove surface dirt e.g. food remnants, grease etc.

Separation and recovery step(s) of plastic material

[0087] Due to the non-oxidizing feature of sulfonic acids, deinking and/or delamination of the plastic material can occur with no depolymerization, no dissolution and/or no degradation of the plastic material by using methods according to the invention, allowing the recovery of the delaminated and/or deinked plastic material. The present method thus allows to obtain or recover one or more polymer fractions from a plastic material. Particularly advantageous, the present method enables recycling of one or more polymer fractions from plastic waste for further valorization. To recoverthe delaminated and/or deinked plastic material, it has to be separated from the mixture. This can be performed via traditional separation techniques such as filtration, e.g. vacuum filtration, although other techniques such as decantation, gravity separation, froth flotation or wind sifting could be an option as well. Accordingly, in certain embodiments, the method further comprises a step of separating the deinked and/or delaminated plastic material, for example the polymer layer(s) or deinked polymer layer(s) from the mixture. In particular embodiments, the deinked and/or delaminated plastic material, for example the polymer layer(s) or deinked polymer layer(s) may be separated from the mixture by filtration, for example by vacuum filtration.

[0088] In further embodiments, when plastic material comprising a multilayered structure is used, the method may further comprise a step of separating the delaminated polymer layers of the plastic material from one another. The skilled person may rely on well-known separation technologies to achieve this, for example, using wind shifting, density separation and/or near infra-red (NIR) separation. The present method thus allows to obtain or recover one or more substantially pure polymer fractions from e.g. plastic waste.

[0089] Also provided herein is deinked and delaminated plastic material obtainable by the method according to the invention.

[0090] Further provided herein is a polymer fraction of a deinked and delaminated plastic material obtainable by the method according to the invention. As used herein a “deinked” plastic material refers to a plastic materials as defined herein, wherein the amount of ink present on the plastic material following the method of the invention is less than the amount of ink on the plastic material prior to contacting the sulfonic acid or the mixture comprising the sulfonic acid. For example, the amount of ink remaining on a deinked plastic material may be less than 70%, less than 60%, less than 50%, less than 40%, less than 30%, less than 20%, or less than 10% of the amount of ink present on the plastic material prior to being contacted with the sulfonic acid or the mixture comprising the sulfonic acid. The ink may also be completely removed from the plastic material, i.e. the plastic material may be fully deinked.

[0091] Before processing of the deinked and delaminated plastic material, or the polymer fraction, they may need to be rinsed e.g. with water in order to remove sulfonic acid traces or traces of any compound present in the mixture comprising the sulfonic acid from the plastic material. A rinsing step may also remove e.g. dissolved glue and ink. In embodiments, the method further comprises one or more rinsing or washing steps of the deinked and/or delaminated plastic material, or the polymer fraction.

[0092] After the rinsing or washing step, the deinked and/or delaminated plastic material, or the polymer fraction thereof may be subjected to a drying step.

[0093] In embodiments, the method further comprises: separating the deinked and/or delaminated plastic material from the mixture; optionally separating the delaminated plastic layers of the plastic material from one another to obtain two or more polymer fractions; rinsing the separated deinked and/or delaminated plastic material, or one or more polymer fractions thereof; and optionally drying the rinsed deinked and/or delaminated plastic material, or polymer fraction(s).

[0094] Further, a regranulation and/or agglomeration and/or extrusion step may be performed before (re-)use of the deinked and/or delaminated plastic material, or the polymer fraction(s) thereof.

[0095] Further disclosed herein are uses of the deinked and delaminated plastic material, or the polymer fraction thereof, in industry.

Separation and recovery step(s) of ink

[0096] In certain embodiments, the method may further comprise a step of recovering ink from the mixture. Recovery steps of for example inks or solvents comprise for examples steps using membrane technologies, adsorption technologies and/or distillation.

Separation and recovery step(s) of solvents [0097] Also advantageous, as the sulfonic acid does not react with the other compounds of the mixture, it is possible to recover the solvents with high purity and lower cost compared to other processes wherein the used reagents usually form an azeotropic mixture, thereby lowering the yield and purity of the recovered reagents.

[0098] First, the sulfonic acid and other compounds of the mixture may be separated from the mixture or the remaining mixture (after separating the deinked and delaminated plastic material from the mixture). The mixture or remaining mixture may further comprise ink, glue and/or other components dissolved or liberated from the plastic material. Suitable separation techniques are known to the skilled person and may include, without limitation, centrifugation, filtration techniques (e.g. membrane filtration), precipitation, adsorption, etc. In embodiments, the method further comprises a step of separating the sulfonic acid and/or the other compounds from the mixture or a remaining mixture.

[0099] The recovered sulfonic acid and other compounds can be reused as such e.g. in the method of the invention, or be subjected to a purification step via well-known purification techniques such as distillation.

[00100] In certain embodiments, the method may further comprise a step of recovering the ink from the mixture. Ink may be recovered using well-known techniques such as membrane technologies, adsorption technologies and/or distillation.

[00101]The method to deink and/or to delaminate a plastic material according to the present invention may comprise a continuous or discontinuous (batch) process. In a continuous process the plastic material, the sulfonic acid or the mixture comprising the sulfonic acid, or both the plastic material and the sulfonic acid or the mixture comprising the sulfonic acid can be continuously introduced. In preferred methods, the sulfonic acid and/or the other compounds are reintroduced to contact the plastic material. The sulfonic acid and/or the other compounds are for example reintroduced after being separated from the mixture (or a remaining mixture) to contact the plastic material in the contacting step by means of a looping or recirculation system.

[00102] Some preferred methods for deinking, delaminating or deinking and delamination a plastic material are described in more detail below.

[00103] A first method comprises a method for deinking a plastic material comprising a monolayered structure comprising (exactly) one polymer layer being provided with at least one ink at one surface of the polymer film. The at least one ink is for example applied by means of a printing technique. The at least one ink is optionally covered with a coating layer.

[00104] The method for deinking comprises the steps of contacting the plastic material with sulfonic acid of formula R=(SO)2-OH or with a mixture comprising at least 25 vol% of sulfonic acid of formula R=(SO)2-OH, with R comprising a C1-C10 alkyl or an aryl, with the alkyl or aryl being substituted or non-substituted. [00105]A second method comprises a method for deinking a plastic material comprising a monolayered structure comprising (exactly) one polymer layer. At least one ink is embedded in the polymer layer.

[00106] The method for deinking comprises the steps of contacting the plastic material with sulfonic acid of formula R=(SO)2-OH or with a mixture comprising at least 25 vol% of sulfonic acid of formula R=(SO)2-OH, with R comprising a C1-C10 alkyl or an aryl, with the alkyl or aryl being substituted or non-substituted.

[00107JA third method comprises a method for delaminating a plastic material comprising a multilayered structure comprises at least 2, for example 4, 5, 6, 8 or 10 polymer layers. None of the polymer layers comprises or is provided with an ink.

The polymer layers are for example adhered to each other by means of an adhesive layer, e.g. a glue.

[00108]The method for delaminating comprises the steps of contacting the plastic material with sulfonic acid of formula R=(SO)2-OH or with a mixture comprising at least 25 vol% of sulfonic acid of formula R=(SO)2-OH, with R comprising a C1-C10 alkyl or an aryl, with the alkyl or aryl being substituted or non-substituted.

[00109JA fourth method comprises a method for deinking and delaminating a plastic material comprising a multilayered structure comprises at least 2, for example 4, 5, 6, 8 or 10 polymer layers. The polymer layers are for example adhered to each other by means of an adhesive layer, e.g. a glue. The multilayered structure is provided with at least one ink at the outer surface of the multilayered structure. The at least one ink is for example applied by means of a printing technique. The at least one ink may further by covered, for example with a coating layer.

[00110]The method for delaminating comprises the steps of contacting the plastic material with sulfonic acid of formula R=(SO)2-OH or with a mixture comprising at least 25 vol% of sulfonic acid of formula R=(SO)2-OH, with R comprising a C1-C10 alkyl or an aryl, with the alkyl or aryl being substituted or non-substituted.

[00111]A fifth method comprises a method for deinking and delaminating a plastic material comprising a multilayered structure comprises at least 2, for example 4, 5, 6, 8 or 10 polymer layers. The polymer layers are for example adhered to each other by means of an adhesive layer, e.g. a glue. The multilayered structure is provided with at least one ink. The ink is for example applied on a polymer layer of the multilayered structure, for example applied by a printing technique. After lamination the at least one ink is positioned between two consecutive polymer layers of the multilayered structure.

[00112] The method for deinking and delaminating comprises the steps of contacting the plastic material with sulfonic acid of formula R=(SO)2-OH or with a mixture comprising at least 25 vol% of sulfonic acid of formula R=(SO)2-OH, with R comprising a C1-C10 alkyl or an aryl, with the alkyl or aryl being substituted or non-substituted. [00113] A sixth method comprises a method for deinking and delaminating a plastic material comprising a multilayered structure comprises at least 2, for example 4, 5, 6, 8 or 10 polymer layers. The polymer layers are for example adhered to each other by means of an adhesive layer, e.g. a glue. The multilayered structure comprises at least one polymer layer having an ink embedded in a polymer layer or in a number of polymer layers of the multilayered structure.

[00114] The method for deinking and delaminating comprises the steps of contacting the plastic material with sulfonic acid of formula R=(SO)2-OH or with a mixture comprising at least 25 vol% of sulfonic acid of formula R=(SO)2-OH, with R comprising a C1-C10 alkyl or an aryl, with the alkyl or aryl being substituted or non-substituted.

[00115]The methods described above and the examples that follow serve to merely illustrate the invention and should not be construed as limiting its scope in any way. While the invention has been shown in only some of its forms, it should be apparent to those skilled in the art that it is not so limited, but is susceptible to various changes and modifications without departing from the scope of the invention.

Brief description of the drawings

[00116] The present invention will be discussed in more detail below, with reference to the attached drawings, in which:

Figure 1 illustrates the deinking and delamination of various types of plastic films using a single step process whereby the plastic films are contacted with a mixture comprising methanesulfonic acid: cyclohexane (70:30 v%). Sample compositions from left to right: A monolayer PP film printed with a UV-crosslinked ink, a monolayer white PP film printed with a UV flexo-crosslinked ink, a transparent multilayer PP/PP film printed with a UV- crosslinked ink, a multilayer magenta colored PE/OPP film and a multilayer black colored PET/AI/PE film.

Description of embodiments

[00117]The present invention will be described with respect to particular embodiments and with reference to certain drawings but the invention is not limited thereto but only by the claims. The drawings are only schematic and are non-limiting. The size of some of the elements in the drawing may be exaggerated and not drawn on scale for illustrative purposes. The dimensions and the relative dimensions do not correspond to actual reductions to practice of the invention.

[00118] When referring to the endpoints of a range, the endpoints values of the range are included. [00119]When describing the invention, the terms used are construed in accordance with the following definitions, unless indicated otherwise. [00120]The term ‘and/or’ when listing two or more items, means that any one of the listed items can by employed by itself or that any combination of two or more of the listed items can be employed.

[00121]The terms ‘first’, ‘second’ and the like used in the description as well as in the claims, are used to distinguish between similar elements and not necessarily describe a sequence, either temporally, spatially, in ranking or in any other manner. It is to be understood that the terms so used are interchangeable under appropriate circumstances and that the embodiments of the invention described herein are capable of operation in other sequences than described or illustrated herein. [00122] The terms “wt%,” “vol%”, or “mol%” refers to a weight percentage of a component, a volume percentage of a component, or molar percentage of a component, respectively, based on the total weight, the total volume of material, or total moles, which includes the component. The term “wt%” and “weight%” are used as synonyms herein.

Examples

Material and methods

[00123]The printed monolayer and multilayer plastic films were supplied by a printing manufacturing company.

[00124]Some of the tested sulfonic acids are methanesulfonic acid (>99.0%, by Merck KGaA), benzenesulfonic acid (98%, by Merck KGaA), 1 -propanesulfonic acid (>99.0%, by Merck KGaA), naphthalene-2-sulfonic acid (98%, by Fisher Scientific), 4-hydroxybenzenesulfonic acid (>85%, by TCI), dodecylbenzene sulfonic acid (>96%, by ThermoFisher Scientific), and 2-aminoethanesulfonic acid (taurine) (>99%, by Merck KGaA).

Some of the hydrocarbons are cyclohexane (>99%, by Fisher Scientific), hexane (95%, by Merck KGaA), n-octane (>98%, by Fisher Scientific), and decane (>99.5%, by TCI).

Some of the tested oxidizing agents are hydrogen peroxide (30%, by VWR Chemicals), sulfuric acid (95-97%, by Merck KGaA), and nitric acid (70%, by Merck KGaA). Sulfonic acids, hydrocarbons, and oxidizing agents were used as received without any further purification.

The mixture comprising at least 25 vol% sulfonic acid and at least 10 vol% hydrocarbons or oxidizing agents was brought into contact with the printed plastic films at temperatures above 50 °C under continuous agitation. Deinked and delaminated plastic films were recovered from the medium by filtration.

Example 1

[00125JA multilayer plastic packaging film comprising a polyethylene terephthalate (PET) layer, a nitrocellulose-based black ink, an urethane-based white ink, a polyurethane-based adhesive, an aluminium layer and a polypropylene (PP) layer, in this sequence, was reduced in size to squares with a side length of 2 cm. These plastic films were brought into contact with methanesulfonic acid at 60 °C under continuous stirring with an agitator at 500 rpm during 30 minutes. The multilayer plastic film was fully deinked and delaminated to its constituent polymer layers. The transparent delaminated plastic films (PET and PP) and the aluminium layer were separated from the mixture via filtration.

Example 2

[00126JA monolayer cyan colored oriented PP (OPP) film containing an UV-flexo-cross linked ink and a coating layer was reduced in size to squares with a side length of 1 cm. These plastic films were brought into contact with the mixture comprising 2- aminonaphtalane 1-sulfonic acid (taurine) and cyclohexane (30:70 vol%) at 85 °C under continuous stirring with an agitator at 400 rpm during 15 minutes. The transparent OPP film was separated from the medium via filtration.

Example 3

[00127JA multilayer plastic packaging film comprising an oriented polypropylene (OPP) layer, a nitrocellulose-based magenta ink, a polyurethane-based adhesive and a PE layer, in this sequence, was reduced in size to squares with a side length of 0.5 cm. These plastic films were brought into contact with the mixture comprising 2-aminoethanesulfonic acid (taurine) and cyclohexane (80:20 vol%) at 60 °C under continuous stirring with an agitator at 500 rpm during 20 minutes. The multilayer plastic film was fully deinked and delaminated to its constituent polymer layers. The transparent delaminated plastic films (OPP and PE films) were separated from the medium via filtration.

Example 4

[00128JA monolayer plastic packaging film comprising an OPP layer, a nitrocellulose/polyurethane resin, and a solvent-based black ink layer, respectively, was reduced in size to squares with a side length of 2 cm. These plastic films were brought into contact with the mixture comprising methanesulfonic acid and hydrogen peroxide (50:50 vol%) at 70 °C under continuous stirring with an agitator at 500 rpm during 10 minutes. The transparent OPP film was separated from the medium via filtration.

Example 5

[00129JA monolayer plastic packaging film comprising a transparent oriented polypropylene (OPP) substrate, a cross-linked acrylate resin, an UV-based white ink layer and a cyan ink on the top layer, was reduced in size to squares with a side length of 1 cm. These plastic films were brought into contact with the mixture comprising benzenesulfonic acid and octane (60:40 vol%) at 60 °C under continuous stirring with an agitator at 500 rpm during 10 minutes. The transparent OPP film was separated from the medium via filtration. Example 6

[00130JA monolayer PP film printed with a UV-crosslinked ink, a monolayer white PP film printed with a UV flexo-crosslinked ink, a transparent multilayer PP/PP film printed with a UV-crosslinked ink, a multilayer magenta colored PE/OPP film and a multilayer black colored PET/AI/PE film (from left to right, respectively as shown in Figure 1) were reduced in size to a side length of 1 cm. These plastic films were brought into contact with the mixture comprising methanesulfonic acid and cyclohexane (70:30 vol%) at 60 °C under continuous stirring with an agitator at 500 rpm during 30 minutes. The delaminated and deinked plastic films were separated from the medium via filtration.

Example 7

A transparent multilayer plastic packaging film comprising an oriented polypropylene (OPP) layer, a polyurethane-based adhesive and a PE layer, in this sequence, was reduced in size to squares with a side length of 1 cm. These plastic films were brought into contact with methanesulfonic acid at 60 °C under continuous stirring with an agitator at 500 rpm during 30 minutes. The multilayer plastic film was fully delaminated to its constituent polymer layers. The transparent delaminated plastic films (OPP and PE films) were separated from the medium via filtration.

Example 8

A transparent multilayer plastic packaging film comprising an oriented polypropylene (OPP) layer, a polyurethane-based adhesive and a PE layer, in this sequence, was reduced in size to squares with a side length of 1 cm. These plastic films were brought into contact with the mixture comprising methanesulfonic acid and cyclohexane (70:30 vol%) at 60 °C under continuous stirring with an agitator at 400 rpm during 45 minutes. The multilayer plastic film was fully delaminated to its constituent polymer layers. The transparent delaminated plastic films (OPP and PE films) were separated from the medium via filtration.

Example 9

A transparent multilayer plastic packaging film comprising an oriented polypropylene (OPP) layer, a polyurethane-based adhesive and a PE layer, in this sequence, was reduced in size to squares with a side length of 1 cm. These plastic films were brought into contact with the mixture comprising methanesulfonic acid and hydrogen peroxide (50:50 vol%) at 60 °C under continuous stirring with an agitator at 400 rpm during 45 minutes. The multilayer plastic film was fully delaminated to its constituent polymer layers. The transparent delaminated plastic films (OPP and PE films) were separated from the medium via filtration.

Claims

1 . A method for deinking and/or delaminating a plastic material, the plastic material comprising a monolayered structure or a multilayered structure, the monolayered structure comprises one polymer layer comprising or being provided with at least one ink, the multilayered structure comprising at least two polymer layers, whereby the multilayered structure or one or more polymer layer optionally comprises or is optionally provided with at least one ink, the method comprising contacting the plastic material with sulfonic acid of formula R=(SO)2-OH or with a mixture comprising at least 25 vol% of sulfonic acid of formula R=(SO)2-OH, with R comprising a CICI 0 alkyl or an aryl, with the alkyl or aryl being substituted or non-substituted.

2. The method according to claim 1 , wherein R comprises a C1-C4 alkyl, a phenyl, tolyl, xylyl or naphthyl.

3. The method according to claim 1 or claim 2, wherein the alkyl or aryl is substituted with one or more hydroxyl, one or more halogen such as F, Cl or Br or one or more amine group.

4. The method according to any one of the preceding claims, wherein the sulfonic acid is selected from the group consisting of methanesulfonic acid (MSA), ethanesulfonic acid, propane sulfonic acid, trifluoromethanesulfonic acid (TFMSA), benzenesulfonic acid (BSA), substituted benzenesulfonic acid, p-toluenesulfonic acid (PTSA), 4-biphenylsulfonic acid, 2- naphtalenesulfonic acid (2-NSA), 1-naphthol-4-sulfonic acid, 4-aminobenzenesulfonic acid, 2-amino-1-naphthalenesulfonic acid, 2-aminoethanesulfonic acid and 4- hydroxybenzenesulfonic acid.

5. The method according to any one of the preceding claims, wherein the mixture further comprises at least one hydrocarbon and/or at least one oxidizing agent.

6. The method according to claim 5, wherein the hydrocarbon comprises an alkane or cycloalkane having 5 to 12 carbon atoms.

7. The method according to claim 5, wherein the oxidizing agent comprises hydrogen peroxide, inorganic acids such as sulfuric acid, ozone, hypochloride or nitrous oxide.

8. The method according to any one of the preceding claims, wherein the temperature at which the plastic material is contacted with the sulfonic acid or with the mixture comprising the sulfonic acid is between 50 and 100 °C.

9. The method according to any one of the preceding claims, wherein the monolayered structure or a multilayered structure comprises a polymer layer comprising a polymer selected from the group consisting of polyolefins (such as polyethylene (PE), including low-density polyethylene (LDPE) and high-density polyethylene (HDPE), and polypropylene (PP)), polyethylene terephthalate (PET), polyurethanes (PU), polyamides (PA), polystyrenes (PS), polycarbonates (PC), ethyl vinyl alcohols (EVOH), ethylene vinyl acetates (EVA), polyvinyl chlorides (PVC), and copolymers thereof.

10. The method according to any one of the preceding claims, wherein the plastic material comprises or is provided with an ink such as one type of ink or a plurality of different types of ink, and/or wherein the plastic material is a multilayer plastic material.

11. The method according to any one of the preceding claims, further comprising a step of separating a deinked and/or delaminated plastic material from the sulfonic acid or from the mixture comprising the sulfonic acid and optionally separating delaminated plastic layers from each other.

12. The method according to any one of the preceding claims, further comprising a step of recovering the sulfonic acid and/or the at least one hydrocarbon and/or the at least one oxidizing agent from the mixture and optionally purifying the sulfonic acid and/or the at least one hydrocarbon and/or the at least one oxidizing agent.

13. The method according to any one of the preceding claims, further comprising a step of reducing the size of the plastic material before the contacting step.

14. The method according to any one of the preceding claims, wherein the plastic material is deinked and delaminated in a single step.