Method for producing a purified fiber fraction from used beverage cartons

Abstract

The present invention relates to a method for producing a purified fiber fraction from used beverage cartons (UBC), the method comprising the steps of: a) subjecting a UBC starting material to a polymer and aluminum membrane separation process to obtain a UBC polymer and aluminum fraction and a raw UBC fiber fraction; b) optionally subjecting the raw UBC fiber fraction to a coarse screening process to remove coarse particles; and c) subjecting the raw UBC fiber fraction to a fine screening process to remove cellulose fines and fine contaminants, the fine screening process comprising at least one fine screen. d) optionally subjecting the fine screened UBC fiber fraction to a washing method to further remove contaminants; e) optionally subjecting the fine screened UBC fiber fraction to a bleaching method; f) subjecting the fine screened, optionally bleached UBC fiber fraction to a dewatering method to a concentration of at least 20% by weight; and g) subjecting the dewatered UBC fiber fraction to inactivation to obtain a purified UBC fiber fraction.

Description

[Technical field]

[0001] The present disclosure relates to a method for recycling fiber fractions from used beverage cartons (UBC). [Background technology]

[0002] Beverage cartons' multi-layer construction offers a resource-efficient, lightweight and recyclable packaging solution that can be made from renewable resources. Sustainably sourced virgin cellulose fibres provide strength and rigidity, while the other layers provide barriers against liquids, water vapour, oil / grease, oxygen and light to protect the packaged contents. The right combination of materials ensures food safety during transport and storage, and prevents food spoilage and waste by protecting the contents from deterioration. These barrier layers consist of a variety of polymers, or combinations of polymers and aluminium foil or coatings, depending on the type of product being packaged and whether the product is kept refrigerated or distributed and stored at room temperature.

[0003] In its simplest form, a beverage carton comprises at least one paperboard layer and at least one liquid barrier layer, usually a polyolefin layer. The beverage carton may further comprise additional barrier layers, typically aluminum foil or coating layers, or high barrier polymer layers such as polyamide or EVOH. Such beverage cartons are often referred to as aseptic beverage cartons, as they are often used for aseptic packaging.

[0004] The general construction of an aseptic carton includes an outer layer of polyolefin, usually LDPE (low density polyethylene), which provides a moisture and liquid barrier, protects the printing ink layers applied to the substrate, and allows the package to be heat sealed. The type of paperboard used depends on the product being packaged, the market it is sold to, and the manufacturing conditions, but is usually a two- or three-ply, or up to five-ply material with an outer layer that is bleached or coated with clay, often containing CTMP (chemi-thermomechanical pulp), TMP (thermomechanical pulp), brown pulp, or high-yield pulp; the paperboard gives the package the necessary mechanical rigidity and usually accounts for about 65-75% of the total package weight. The inside of the paperboard is coated with LDPE, which bonds with an aluminum foil layer that provides an odor, light, and gas barrier. Adhesion of the aluminum foil to the innermost plastic layer is achieved, for example, by the use of a bonding layer of EMAA (poly(ethylene-co-methacrylic acid)). Finally, an inner layer of LDPE is applied to allow the carton to be heat sealed.

[0005] The term used beverage carton (UBC) is used herein to denote post-consumer beverage cartons, in particular post-consumer sterile beverage cartons, which are obtained from containers and packaging materials that have been collected after use.

[0006] The composition of UBC is different compared to many other recycled materials. UBC is typically characterized by the following: Large quantities of bleached or unbleached synthetic, semi-synthetic or mechanical fibres High plastic content High aluminum content from foils and coatings Food or liquid residues High bacterial (microorganism) content High amount of organic material including various oils and fats High content of monovalent and polyvalent ions or salts Possible presence of heavy metals · Non-intentionally added substances (NIAS) Mixed waste containing packaging and packaging items, such as disposable parts (long strings of material such as caps, straws and packaging wires)

[0007] The collected UBC may contain printing inks and varnishes. Although the majority of the fibers are not usually directly exposed to printing inks, dissolved ink or ink debris may be redeposited on the fibers during the degradation process.

[0008] Recycling can be categorized as primary, secondary, tertiary, and quaternary. Primary recycling refers to the reprocessing of materials back into their original use or into a comparable product of equal or better quality, which is not currently an option since used cartons cannot be returned directly to their original use. Secondary recycling is the most widespread recycling option for UBC, where the material is processed and used in applications that do not require the virgin material properties. The paper fibers are separated from the polymer and aluminum residues (also referred to herein as poly-Al residues) and the fibers are incorporated into paper products. Another secondary recycling process involves converting shredded UBC into construction materials. Tertiary recycling involves breaking down the product into its chemical components and then recycling those chemicals into various products. Quaternary recycling of UBC involves incineration with energy recovery, although this process is not considered recycling in many countries.

[0009] Due to its multi-layered structure and unique composition, UBC is difficult to recycle and reuse efficiently. As a result, today, UBC is often collected and disposed of in landfills, incinerated, or processed into various low-value fractions, such as polymer-rich, fiber-rich, and wastewater or sludge fractions. The fiber-rich fraction is typically used in composites, non-food packaging applications, and other grades where higher impurity content is acceptable, such as tissue, towels, liners, and writing paper.

[0010] Paperboard typically constitutes 65-75% of the total weight of a carton, so recovery of this fraction is the primary focus of carton recycling approaches. Recycling can be accomplished by recovering the paper fibers using a conventional Hydrapulper or drum pulper at the paper mill. A Hydrapulper is a large cylindrical vessel with an impeller at the bottom that breaks down the paper fibers, producing a relatively dilute slurry of fibers that can be further processed in a mill. Contact of the water with the paper layers occurs in the Hydrapulper, and the layers are separated by hydraulic forces inside the pulper. No chemicals are required, but solvents and acid or alkaline solutions may be used to improve separation efficiency. The consistency of the pulp in the Hydrapulper is typically less than 15% by weight. Hydrapulpers are generally equipped with a lager that removes long string-like material such as PolyAl residue, caps, straws, and baling wire from the slurry. After removal of the consistency of the PolyAl residue from the pulper, the PolyAl residue is washed in a rotating perforated cylinder to recover entrained fibers. Drum pulpers are essentially rotating, tilting drums equipped with baffles to separate debris from the fibers with minimal fiber loss in the pulping and screening sections.

[0011] Although many paper mills have Hydrapulpers capable of recycling UBC, the fact that the theoretical maximum yield is only 75%, compared to 85% or more for other paper packaging, is a disincentive, as is the challenge of economically processing the PolyAl residues. Furthermore, recovered UBC fibers contain high amounts of impurities, especially from food residues and non-intentionally added substances (NIAS), which may make them unsuitable for blending into virgin or less contaminated pulp streams. Currently, there are strict regulations and limitations on the use of recycled materials in the boardmaking process. Fibers obtained from UBC may contain components that should not be returned to the boardmaking process. Examples include plastic particles, metals, metal compounds, optical brighteners (OBAs) or fluorescent whitening agents (FWAs), ink residues or mineral oils, especially microorganisms, toxic components, and food residues. These impurities may interfere with the wet-end chemistry (process performance), but may also affect the properties of the final product (mechanical or product performance, barrier properties, impurities, microbial growth, etc.).

[0012] Fibers derived from UBC can often exhibit high microbial activity or high microbial load, and microbial inactivation or sterilization of the fiber or pulp is typically required prior to reuse.

[0013] Another challenge with recycled UBC is that fibers derived from UBC are considered to be downgraded when they are recycled and reused. This downgrading is in part due to a reduction in mechanical properties caused by excessive mechanical and chemical processing. Recycled fibers may be mechanically damaged or processed in ways that affect their strength, mechanical performance, etc.

[0014] Generally, only virgin paper fibres are used in the manufacture of paperboard for food or beverage packaging applications. There is a need to increase the amount of recycled fibres in paperboard for food packaging applications. It is generally believed that due to the high levels of contamination, microbial load and degradation of recycled materials, UBC fibres cannot be efficiently reused in food and beverage packaging laminates and products.

[0015] There is therefore a need to find a way to enable pulp from UBC to be used in food or beverage packaging substrates and laminates, especially at high contents, without affecting the mechanical properties of the substrates and laminates or posing a risk of contamination of the packaged contents. Summary of the Invention

[0016] It is an object of the present disclosure to provide a method by which pulp from used beverage cartons (UBC) can be reused in applications and products where typically only virgin paper fiber is used, such as food or beverage packaging substrates and laminates.

[0017] An objective of the present disclosure is to provide a fiber fraction from UBC with suitable chemical purity for reuse in food or beverage packaging substrates and laminates.

[0018] An object of the present disclosure is to provide a fiber fraction from UBC that has the biological purity required or suitable for reuse in food or beverage packaging substrates and laminates.

[0019] An object of the present disclosure is to provide a fiber fraction from UBC that has suitable mechanical properties for reuse in food or beverage packaging substrates and laminates.

[0020] The above objectives, as well as other objectives which will be realized by those skilled in the art in light of the present disclosure, are accomplished by various aspects of the present disclosure.

[0021] The present invention is based on the realization that it has been found that subjecting the raw UBC fiber fraction obtained after removal of the PolyAl residues to a fine screening process to remove fines and fine materials significantly accelerates the subsequent cleaning, bleaching and passivation of the UBC fiber fraction.

[0022] The relatively small amount of fines in the recycled UBC fiber fraction contributes to the high level of impurities in the fiber fraction, high water retention and / or high drain resistance. Fine screening to remove fines and fine-like matter removes a significant portion of the particulate contaminants and reduces the drain resistance, allowing repeated washing steps to be carried out in less time, resulting in a fiber fraction of higher purity.

[0023] The fine screening process, which removes fines and fines, also facilitates bleaching and inactivation of the UBC fiber fraction by reducing the amount of bleaching or inactivation chemicals required to achieve the desired bleaching or inactivation results, respectively. Additionally, removal of fines, fines, and contaminants may also reduce interference with wet-end chemistry when the UBC fiber fraction is reused in a pulping process or in a paper, paperboard, or moldable fiber manufacturing process.

[0024] According to a first aspect presented herein, there is provided a method for producing a recyclable fiber fraction from used beverage cartons (UBC), the method comprising: a) subjecting the UBC starting material to a polymer and aluminum membrane separation process to obtain a UBC polymer and aluminum fraction and a raw UBC fiber fraction; b) optionally subjecting the raw UBC fiber fraction to a coarse screening process to remove coarse particles; c) subjecting the raw UBC fiber fraction to a fine screening process to remove cellulose fines and fine contaminants, the fine screening process comprising at least one fine screening step and at least one dilution step; d) optionally subjecting the fine screened UBC fiber fraction to a washing process to further remove contaminants; e) optionally subjecting the fine screened UBC fiber fraction to a bleaching process; f) subjecting the fine screened, optionally bleached UBC fiber fraction to a dewatering process to a consistency of at least 20% by weight; g) subjecting the dehydrated UBC fiber fraction to an inactivation method to obtain a purified UBC fiber fraction; A method comprising:

[0025] The purified UBC fiber fraction obtained according to the methods of the present invention is preferably suitable for demanding end uses, such as direct or indirect contact with food.

[0026] In addition to cellulose fibers, the collected UBC (herein referred to as UBC starting material) also contains a high content of plastic materials, mainly polyolefins, and a high content of aluminum from the foil and / or coating. In some embodiments, the UBC starting material in step (a) contains at least 15% by weight, and in some embodiments at least 20% by weight, plastic, based on dry weight. In some embodiments, the UBC starting material in step (a) contains at least 0.3% by weight, and preferably at least 1% by weight, aluminum or aluminum compounds, based on dry weight. In some embodiments, the UBC starting material in step (a) contains at least 15% by weight, plastic and at least 0.3% by weight, aluminum or aluminum compounds, preferably at least 20% by weight, plastic and at least 1% by weight, aluminum or aluminum compounds, based on dry weight.

[0027] It may be preferred that the UBC starting material is selected or screened so that the content of optical brightener in the UBC is not too high. In some embodiments, the UBC starting material in step (a) comprises less than 1 wt.% optical brightener (OBA).

[0028] To obtain a raw fiber fraction suitable for further washing and inactivation, the plastic and / or aluminum content is first removed. This is done by a) subjecting the UBC starting material to a polymer and aluminum film separation process to obtain a UBC polymer and aluminum fraction and a raw UBC fiber fraction. If the UBC starting material does not contain aluminum, the UBC polymer and aluminum fraction may contain only polymer and no aluminum. The resulting raw UBC fiber fraction is composed mainly of cellulosic material and contains significantly less plastic and aluminum than the UBC starting material. The polymer and aluminum film separation process may include chopping the UBC starting material and mixing the chopped UBC starting material with water or an aqueous solution. When the mixture is agitated, the fibers absorb the water and the plastic and aluminum layers of the laminate break apart. The various fractions are separated by mechanical filtration and / or flotation to obtain the UBC polymer and aluminum fraction and the raw UBC fiber fraction.

[0029] The raw UBC fiber fraction obtained in step (a) preferably comprises at least 80% by weight of cellulose fibers on a dry weight basis. In some embodiments, the raw UBC fiber fraction obtained in step (a) preferably comprises at least 90% by weight of cellulose fibers, preferably at least 95% by weight of cellulose fibers on a dry weight basis.

[0030] In some embodiments, the raw UBC fiber fraction obtained in step (a) has a Shopper-Riegler (SR) value, determined by standard ISO 5267-1, in the range of 15 to 35, preferably in the range of 18 to 30.

[0031] In some embodiments, the raw UBC fiber fraction obtained in step (a) has a water retention value (WRV) determined by standard ISO 23714 in the range of 110-200%, preferably in the range of 120-180%, more preferably in the range of 125-175%.

[0032] In some embodiments, the untreated UBC fiber fraction obtained in step (a) has a "Fines A" content of greater than 22%, preferably greater than 25%, as measured using an FS5 fiber optic analyzer (Valmet).

[0033] In some embodiments, the raw UBC fiber fraction obtained in step (a) comprises more than 1 wt. % plastics, preferably more than 1.2 wt. % plastics, based on dry weight.

[0034] In some embodiments, the raw UBC fiber fraction obtained in step (a) contains more than 0.2 wt. % aluminum, preferably more than 0.5 wt. % aluminum, based on dry weight.

[0035] In some embodiments, the untreated UBC fiber fraction obtained in step (a) contains more than 20 mg / kg mineral oil saturated hydrocarbons (MOSH), preferably more than 50 mg / kg MOSH, on a dry weight basis.

[0036] In some embodiments, the raw UBC fiber fraction obtained in step (a) contains more than 20 mg / kg mineral oil aromatic hydrocarbons (MOAH), preferably more than 50 mg / kg MOAH, on a dry weight basis.

[0037] In some embodiments, the raw UBC fiber fraction obtained in step (a) comprises more than 5000 mg / kg extractables, preferably more than 10000 mg / kg extractables, on a dry weight basis.

[0038] In some embodiments, the raw UBC fiber fraction obtained in step (a) comprises more than 1000 mg / kg unsaturated fatty acids, preferably more than 2000 mg / kg unsaturated fatty acids on a dry weight basis.

[0039] In some embodiments, the raw UBC fiber fraction obtained in step (a) comprises more than 400 mg / kg resin acids, preferably more than 500 mg / kg resin acids on a dry weight basis.

[0040] The amount of extractant, unsaturated fatty acids, and resin acids were measured using the SCAN-CM49 method, in which the pulp was acidified to a pH < 3 using acetic acid. Extraction was performed by ASE (accelerated solvent extraction) using acetone at a temperature of 100°C and a pressure of 2000 psi for two cycles. Extracts were analyzed by GC-FID and calculated against an internal standard.

[0041] In some embodiments, the raw UBC fiber fraction obtained in step (a) has an ash content of more than 4% at 525° C. and / or more than 4% at 925° C. Raw UBC fiber fractions obtained from some types of sources, including mineral or pigment coated paper cartons, may also have significantly higher ash contents.

[0042] In some embodiments, the raw UBC fiber fraction is subjected to a coarse screening process to remove coarse particles. As used herein, the term coarse particles generally refers to particles having a diameter or width greater than 1 mm.

[0043] The raw UBC fiber fraction may still contain small amounts of plastic and aluminum, mainly in the form of fines that are not removed by conventional methods for separating polymer and aluminum films. These fines, together with cellulose fines formed by the degradation of cellulosic materials, are largely responsible for the retention of high levels of impurities, high water retention, and / or high drain resistance of the fiber fraction.

[0044] The term cellulose fines as used herein generally refers to cellulose particles that are significantly smaller in size than cellulose fibers.

[0045] In some embodiments, the term cellulose fines as used herein refers to cellulosic fines, which are capable of passing through a 200 mesh screen (76 μm equivalent hole diameter) of a conventional laboratory fractionation device (SCAN-CM66:05). There are two main fiber fines, namely, primary fines and secondary fines. Primary fines are generated during pulping and bleaching and are removed from the cell wall matrix by chemical and mechanical treatments. As a result of their origin (i.e., complex intermediate lamellae, striated cells, parenchymal cells), primary fines exhibit a flake-like structure with only a small proportion of fibrous material. In contrast, secondary fines are generated during the refining of the pulp. Both primary and secondary fines increase the drain resistance of the pulp and reduce the dewatering rate in the forming section of the paper machine. The high specific surface area of ​​fines compared to pulp fibers affects the retention of process chemicals, significantly affecting the process stability and end product performance.

[0046] Unlike conventional wire dewatering papermaking processes, the holdup of fines in this system is preferably kept low to allow for more efficient dewatering / drainage in subsequent washing, bleaching and passivation.

[0047] In some embodiments, the term particulate contaminants as used herein refers to particulates that are not derived from cellulosic materials and are capable of passing through a 200 mesh screen (76 μm equivalent hole diameter) of a conventional laboratory sorting device (SCAN-CM66:05).

[0048] To remove a portion of the cellulose fines and particulate contaminants from the raw UBC fiber fraction, the raw UBC fiber fraction is subjected to a fine screening process to remove the cellulose fines and particulate contaminants, the fine screening process including at least one fine screening step and at least one dilution step.

[0049] The fine screening method used to remove cellulose fines and particulate contaminants from the raw UBC fiber fraction includes at least one fine screening step. The fine screening step can include screening using one or more pressure screens, one or more hydrocyclones, one or more belt filters, or a combination thereof. Other screening methods known to those skilled in the art for removing fines from fiber mixtures can also be used.

[0050] The fine screening method used to remove cellulose fine and particulate contaminants from the raw UBC fiber fraction comprises at least one dilution step. The dilution step preferably comprises adding a diluent, preferably water or an aqueous solution, to reduce the concentration of the UBC fiber fraction. The dilution step may be performed before and / or after the fine screening step. Preferably, the dilution is performed at least before the fine screening step to reduce the concentration of the UBC fiber fraction before the fine screening step. The concentration of the UBC fiber fraction after dilution may vary depending on the screening or fractionation method used. In some embodiments, the dilution factor (DF) is >2, preferably >2.5, >3.0, >3.5, >4, >4.5 or >5. Preferably, the dilution step comprises diluting the UBC fiber fraction to a concentration in the range of 0.1-7 wt.%, preferably in the range of 0.3-5 wt.%, more preferably in the range of 0.5-2 wt.%. It is also possible to perform screening with greater consistency, especially at the end of a fine screening method comprising multiple screening steps.

[0051] The method of the invention may preferably comprise an extended fine screening sequence in which at least two fine screening steps and / or at least two dilution steps are performed.

[0052] In some embodiments, the fine screening method in step (c) comprises at least two, preferably at least three, fine screening steps. The fine screening steps may be the same or different.

[0053] In some embodiments, the fine screening method in step (c) comprises at least two, preferably at least three dilution steps. The washing steps may be the same or different.

[0054] In some embodiments, the fine screening and dilution steps in step (c) are repeated successively at least two times, preferably at least three times.

[0055] Examples of possible fine screening / dilution sequences: Screening - Rare - Screening Screening-Dilution-Screening-Dilution Screening-Dilution-Screening-Dilution-Screening Dilution-Screening-Dilution Dilution-Screening-Dilution-Screening-Dilution Dilution-Screening-Dilution-Screening-Dilution-Screening

[0056] In some embodiments, the fine screening process in step (c) reduces the content of fines and particulate contaminants in the UBC fiber fraction by at least 20%, preferably at least 30%, more preferably at least 40%. More specifically, in some embodiments, the fine screening process in step (c) reduces the fines content in the UBC fiber fraction by at least 20%, preferably at least 30%, more preferably at least 40%, where the fines content, "Fines A", is measured using an FS5 fiber optic analyzer (Valmet).

[0057] In some embodiments, the fine screening method in step (c) reduces "Fine A" to less than 20%, preferably less than 17%, more preferably less than 15%, as measured using an FS5 fiber optic analyzer (Valmet).

[0058] In some embodiments, the fine screening process in step (c) removes between 0.1 and 10%, or between 0.1 and 7.5%, or between 0.1 and 5% by weight of the solids of the untreated UBC fiber fraction.

[0059] The finely sorted UBC fiber fraction is optionally subjected to further washing methods to remove further contaminants, particularly dissolved, dispersed, soluble or extractable contaminants. Any suitable pulp washing method for removing contaminants from the pulp mixture can be used. The washing methods used to remove further contaminants from the UBC fiber fraction can include washing using one or more rotary vacuum washers, rotary pressure washers, pressurized and atmospheric diffusion washers, horizontal belt washers and dilution / extraction devices, or combinations thereof. Other washing methods known to those skilled in the art for removing contaminants from fiber mixtures can also be used. The washing method preferably includes two or more washing steps.

[0060] In some embodiments, the fine-screened UBC fiber fraction is subjected to a bleaching method. The bleaching method may, for example, be selected from the group consisting of hydrogen peroxide bleaching, ozone bleaching, oxygen bleaching, chloride bleaching, hypochlorous acid bleaching, and extractive bleaching. In a preferred embodiment, the bleaching is combined with heating the fine-screened UBC fiber fraction to a temperature of 50° C. or higher, for example 80° C. or higher, preferably 90° C. or higher, more preferably 100° C. or higher. The bleaching method may, for example, include a combination of heating and hydrogen peroxide bleaching, or heating and hypochlorous acid bleaching. Such a bleaching method may also preferably lead to at least partial inactivation of the UBC fiber fraction.

[0061] The fine screened and optionally bleached UBC fiber fraction is subjected to a dewatering process to a consistency of at least 20% by weight. In some embodiments, the UBC fiber fraction in step (f) is dewatered to a consistency of at least 30% by weight, preferably at least 40% by weight. Dewatering improves the efficiency of the subsequent inactivation process.

[0062] The inventors have further found that the mechanical properties of the UBC fiber fraction can be further improved for use in food or beverage packaging substrates and laminates by heat treating the UBC fiber fraction at a concentration of at least 20% by weight, preferably at least 30% by weight, more preferably at least 40% by weight. Heat treatment may, for example, include drying the UBC fiber fraction at an elevated temperature. In some embodiments, the UBC fiber fraction is dried at an elevated temperature to a concentration of at least 70% by weight, preferably at least 80% by weight, more preferably at least 90% by weight, before, during, or after being subjected to the inactivation method. Without wishing to be bound by any particular scientific theory, it is believed that the hornification of the UBC fiber fraction caused by heat treatment at a high concentration can improve the mechanical properties of the fiber fraction when used in food or beverage packaging substrates or laminates. Thus, in some embodiments, drying at an elevated temperature results in the hornification of the UBC fiber fraction. The elevated temperature is preferably 80° C. or higher, preferably 90° C. or higher, more preferably 100° C. or higher.

[0063] In some embodiments, the heat treatment is carried out in a heated disperser (also known as a thermal disperser). A heated disperser is a device that uses a combination of heat and mechanical treatment of fibers at high concentrations to liquefy, decompose and disperse sticky visible contaminants. The temperature in the heated disperser is preferably 80°C or higher, preferably 90°C or higher, more preferably 100°C or higher, for example in the range of 110-180°C. The heat treatment in the heated disperser can usually be carried out for 5 seconds to 120 minutes, preferably 5 seconds to 30 minutes. The heat treatment in the heated disperser can improve the dissolution of starch and residual barrier polymers and additives, etc. The heat treatment in the heated disperser can also preferably result in at least partial inactivation of the UBC fiber fraction.

[0064] The dewatered UBC fiber fraction is subjected to an inactivation method to obtain a purified UBC fiber fraction. As used herein, the term "inactivation" refers to microbial inactivation, i.e., a method or treatment that reduces the microbial activity or microbial load of the UBC fiber fraction. The inactivation method kills or inactivates microorganisms and other potential pathogens present in the UBC fiber fraction. The inactivation method may result in complete sterilization or partial inactivation, i.e., disinfection or sanitization, of the fiber fraction.

[0065] Inactivation preferably reduces the microbial activity of the UBC fiber fraction by at least 30%, preferably at least 40%, at least 50%, or at least 60%, for example in the range of 60-100%. Preferably, the inactivation method reduces the microorganisms and other potential pathogens present in the UBC fiber fraction to a level that is normally acceptable for fibers used in food or beverage packaging substrates and laminates. The inactivated purified UBC fiber fraction has suitable chemical purity, suitable biological purity, and suitable mechanical properties for reuse in food or beverage packaging substrates and laminates.

[0066] In some embodiments, the inactivation method includes heat inactivation, chemical inactivation, and / or radiation inactivation. Heat inactivation can be selected from the group consisting of, for example, steam inactivation and dry heat inactivation. Chemical inactivation can be selected from the group consisting of, for example, ethylene oxide, nitrogen dioxide, ozone, glutaraldehyde and formaldehyde, hydrogen peroxide, and peracetic acid inactivation. Radiation inactivation can be selected from the group consisting of, for example, non-ionizing radiation inactivation and ionizing radiation inactivation. Inactivation methods may include a combination of two or more inactivation techniques.

[0067] In some embodiments, the inactivation method is carried out using chemicals that are traditionally used for bleaching fibers used in paper and paperboard. The inactivation can be carried out, for example, using hydrogen peroxide or ozone. Such inactivation using chemicals that are traditionally used for bleaching fibers can be advantageous because it can also lead to at least partial bleaching of the UBC fiber portion.

[0068] In some embodiments, the heat treatment and inactivation method can be combined when the inactivation method involves high temperature. For example, inactivation by autoclave at 121°C also constitutes heat treatment of the UBC fiber portion. As another example, heat treatment in a disperser at a temperature that results in inactivation of the fiber fraction can also constitute an inactivation method.

[0069] The purified UBC fiber fraction obtained according to the method of the present invention is preferably suitable for demanding end uses such as direct or indirect contact with food. The purified UBC fiber fraction obtained in step (g) is suitable for reuse in food or beverage packaging substrates and laminates. The purified UBC fiber fraction can be advantageously reused in food or beverage packaging substrates and laminates, although it is understood that the fiber fraction can also be reused in other types of products such as liners or tissues.

[0070] In some embodiments, the purified UBC fiber fraction in step (g) comprises at least 96% by weight cellulose fiber, preferably at least 98% by weight cellulose fiber, on a dry weight basis.

[0071] In some embodiments, the purified UBC fiber fraction in step (g) has a Shopper-Riegler (SR) value in the range of 15 to 35, preferably in the range of 18 to 30, as determined by standard ISO 5267-1.

[0072] In some embodiments, the purified UBC fiber fraction in step (g) has a water retention value (WRV) determined by standard ISO 23714 in the range of 110-200%, preferably in the range of 120-180%, more preferably in the range of 125-175%.

[0073] In some embodiments, the purified UBC fiber fraction in step (g) has a "Fines A" content of less than 20%, preferably less than 17%, and more preferably less than 15%, as measured using an FS5 fiber optic analyzer (Valmet).

[0074] In some embodiments, the purified UBC fiber fraction in step (g) has a kappa number, measured according to standard ISO 302:2015, of greater than 5, preferably greater than 10, more preferably greater than 20. Purified UBC fiber fractions obtained from some types of sources, for example sources containing mechanical pulp, may have significantly higher kappa numbers, measured according to standard ISO 302:2015, such as 30 or higher or 40 or higher.

[0075] In some embodiments, the purified UBC fiber fraction in step (g) contains less than 0.5% plastic by weight, preferably less than 0.1% plastic by weight, on a dry weight basis.

[0076] In some embodiments, the purified UBC fiber fraction in step (g) contains less than 0.5 wt. % aluminum, preferably less than 0.1 wt. % aluminum, based on dry weight.

[0077] In some embodiments, the purified UBC fiber fraction in step (g) contains less than 0.1 wt % OBA, preferably less than 0.05 wt % OBA, on a dry weight basis.

[0078] In some embodiments, the purified UBC fiber fraction in step (g) contains less than 50 mg / kg mineral oil saturated hydrocarbons (MOSH), preferably less than 20 mg / kg MOSH, on a dry weight basis.

[0079] In some embodiments, the purified UBC fiber fraction in step (g) contains less than 50 mg / kg mineral oil aromatic hydrocarbons (MOAH), preferably less than 20 mg / kg MOAH, on a dry weight basis.

[0080] In some embodiments, the purified UBC fiber fraction in step (g) contains less than 5000 mg / kg extract, preferably less than 4000 mg / kg extract, on a dry weight basis.

[0081] In some embodiments, the purified UBC fiber fraction in step (g) contains less than 800 mg / kg unsaturated fatty acids, preferably less than 600 mg / kg unsaturated fatty acids on a dry weight basis.

[0082] In some embodiments, the purified UBC fiber fraction in step (g) contains less than 200 mg / kg resin acids, preferably less than 100 mg / kg resin acids on a dry weight basis.

[0083] The amount of extractant, unsaturated fatty acids, and resin acids were measured using the SCAN-CM49 method, in which the pulp was acidified to a pH < 3 using acetic acid. Extraction was performed by ASE (accelerated solvent extraction) using acetone at a temperature of 100°C and a pressure of 2000 psi for two cycles. Extracts were analyzed by GC-FID and calculated against an internal standard.

[0084] In some embodiments, the refined UBC fiber fraction in step (g) has an ash content below 2% (at 525° C.) and / or an ash content below 1% (at 925° C.). Refined UBC fiber fractions obtained from some types of sources, including mineral or pigment coated paper cartons, may also have significantly higher ash contents.

[0085] Preferably, at least 99% by weight, more preferably at least 99.5% by weight, and most preferably at least 99.9% by weight of the purified UBC fiber fraction obtained in step (g) is identifiable by chemical analysis.

[0086] In some embodiments, the purified UBC fiber fraction obtained in step (g) is mixed with non-UBC fibers or broken obtained from chemical pulp, chemi-mechanical pulp (CMP), chemi-thermomechanical pulp (CTMP), high temperature chemi-thermomechanical pulp (HT-CTMP), thermo-mechanical pulp (TMP). The fibers may be softwood, hardwood, or non-wood fibers and may be bleached or unbleached.

[0087] In some embodiments, the purified UBC fiber fraction obtained in step (g) is co-purified with non-UBC fiber obtained from chemical pulp, CMP, CTMP, HT-CTMP, TMP, or broke.

[0088] According to a second aspect exemplified herein, there is provided a paper or paperboard product comprising the purified UBC fiber fraction obtained according to the method of the first aspect. In a preferred embodiment, the paper or paperboard product is a food or beverage packaging substrate or laminate. In some embodiments, the paper or paperboard product is a liquid packaging board (LPB).

[0089] While the invention has been described with reference to various exemplary embodiments, those skilled in the art will recognize that various changes can be made and equivalents substituted for elements thereof without departing from the scope of the invention. In addition, many modifications can be made to adapt a particular situation or material to the teachings of the invention without departing from the essential scope thereof. Therefore, it is not to be understood that the invention is limited to the particular embodiment disclosed as the best mode contemplated for carrying out this invention, but the invention is intended to include all embodiments falling within the scope of the appended claims. [Brief description of the drawings]

[0090] [Figure 1] Figure 1 shows the Shopper-Riegler values ​​plotted against the refining specific energy applied to unrefined and refined recycled UBC pulp. [Diagram 2] FIG. 1 shows the Schopper-Riegler values ​​plotted against the water retention value, WRV, of unrefined and refined recycled UBC pulps. [Diagram 3] FIG. 1 is a plot of tensile index versus sheet density for unrefined and refined recycled UBC pulp. [Figure 4] FIG. 1 shows Tear Index plotted against sheet density for unrefined and refined recycled UBC pulp. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0091] Example 1 - Preparation of raw UBC pulp The collected spent UBC starting material was subjected to a polymer and aluminum film separation process to obtain a polymer and aluminum fraction and a fiber fraction. The UBC was treated with water at a consistency of about 18-20 wt. % in a drum pulper (drum speed 10.7 U / min) at about 50°C for 25 min. The polymer aluminum fraction was separated from the UBC and the remaining pulp is referred to here as raw UBC pulp (1). The screening drum was equipped with 8 mm holes. The polymer and aluminum fraction constituted about 30-35 wt. % of the dry weight of the UBC starting material. The fiber composition of the raw UBC pulp was as follows: Bleached softwood kraft: 12% by weight Unbleached softwood kraft: 25% by weight Unbleached hardwood kraft: 20% by weight Coniferous wood CTMP: 33% by weight Hardwood CTMP: 10% by weight

[0092] The results of the fiber and moisture analysis of the raw UBC pulp, designated sample (1), are shown in Tables 1, 2 and 3.

[0093] The amount of extractables in this pulp sample was 13,900 mg / kg (acetone extractable), while the amount of unsaturated fatty acids (free and bound) was 2,365 mg / kg. The amount of resin acids was 511 mg / kg, of which free sterols were 49 mg / kg and bound sterols were 37 mg / kg.

[0094] The pH of the filtrate was 6.74, the amount of suspended solids was 33 mg / L, the BOD after 5 days was 500 mg / L, the COD was 820 mg / L, the phosphorus and total nitrogen contents of the filtrate were 2.1 mg / L and 26 mg / L, respectively.

[0095] Example 2 - Crude Screening of Raw UBC The raw UBC pulp prepared in Example 1 was then diluted and coarsely sieved at a consistency of 1.6 wt%. The screener was equipped with a step rotor next to a contoured hole screen basket to efficiently remove large flat contaminants (rotor speed 730 m / min). The screen holes had a diameter of 1.6 mm. The accept stream (output, consistency 1.4 wt%) was then collected and analyzed. The rejects (reject rate 14 wt%) were subjected to another screening and peeling unit with 2.4 mm screening holes. The accepts were then collected and used as the output stream, while the rejects were subjected to a reject sorter with 2.4 mm holes in the screen (reject sorter, rotor speed 1600 m / min, consistency 2.2 wt%, dilution water 50 L / min). The temperature of the resulting accept stream (consistency 1.4 wt%) was about 37°C. The output stream, designated as sample (2), was analyzed and the results are shown in Tables 1-3.

[0096] Example 3 - Fine screening and washing The output stream from Example 2 was diluted with hot water (68°C) to a consistency of 1% by weight, and then subjected to high speed washing / dewatering and separation by feeding the pulp suspension around a smooth roll in a belt washer under wire tension. The consistency of the pulp after washing and draining was about 12% by weight, and the temperature of the pulp was about 60°C. The washing / dewatering in the belt washer reduced the ash content of the fiber fraction by 49%. The basis weight of the dewatered fiber substrate was about 31 gsm.

[0097] The treated UBC was further subjected to a dilution step, then to a fine screening using two forward screening cleaners (hydrocyclones) at a consistency of 1.4 wt.% (rejection 4.7 wt.%, dilution water 60 l / min), then to a second forward washing step at a consistency of 1.2 wt.% (rejection 5.7 wt.%, dilution water 65 l / min) and to two rotor cleaners (multi-foil rotors) based on the centrifugal screening principle operated in cascade mode at a consistency of 1.3 wt.%, then to a thickening step (inlet concentration 1.2 wt.% and accept concentration 6.1 wt.%. The accept had an ash content of 2.1 wt.%). The temperature of the pulp was about 60-70 °C. The slit size of the screens was 0.15 mm. The obtained refined UBC pulp, indicated as sample (3), was analyzed and the results are shown in Tables 1-3.

[0098] Example 4 - Thickening, heat dispersion, dehydration The fine screened, washed and thickened material obtained in Example 3 was further fed to a screw press and a heated screw and heater (inlet consistency 3.4 wt%, accept consistency 40 wt%, screw speed 50 U / min), followed by a heated disperser at about 115°C (rotor speed 1500 U / min, inlet consistency 35 wt%, gap 4.4 mm, accept consistency 10.5 wt%). The consistency of the pulp after the disperser was 10.5 wt%. Dilution and washing at low consistency (using a high-speed washing / dewatering unit) were carried out, followed by dewatering in a screw press to a consistency of about 30 wt%.

[0099] The washed and screened material, designated as sample (4), was analyzed with the results shown in Tables 1-3. The results showed that a significant amount of extractives could be removed compared to reference sample 1 (unprocessed UBC pulp). The amount of extractives in this pulp sample was 3200 mg / kg (acetone extractables), while the amount of unsaturated fatty acids (free and bound) was 591 mg / kg. The amount of resin acids was 62 mg / kg, of which the amounts of free and bound sterols were 15 and 8 mg / kg, respectively.

[0100] The pH of the filtrate was 8.4, the amount of suspended solids was 16 mg / l, and after 5 days the BOD was 13 mg / l and the COD was 44 mg / l. The phosphorus and total nitrogen contents of the filtrate were 0.7 mg / l and <1 mg / l, respectively.

[0101] Example 5 - Heat and high concentration inactivation The material obtained in Example 4 was further subjected to a screening press and a heating screen operated at T>80°C, and further subjected to a high consistency disperser, also operated at a high temperature, the purpose of which was to further dewater the pulp and inactivate the microbial activity at higher consistency. After the high consistency disperser, the pulp was inactivated at high consistency using 3.3% peroxide, NaOH and silicate at a temperature of about 85°C. The purpose of this treatment was to inactivate any remaining microbial activity.

[0102] The resulting inactivated UBC pulp, designated as sample (5), was analyzed and the results are shown in Tables 1-3. The results show that the amount of extractables, for example, can be further reduced, but also that microbial activity is greatly reduced. The amount of extractables in this pulp sample was 2500 mg / kg (acetone extractables), while the amount of unsaturated fatty acids (free and bound) was 495 mg / kg. The amount of resin acids was 49 mg / kg, and free and bound sterols were reduced to 11 mg / kg and 8 mg / kg, respectively.

[0103] Example 6 Comparative - UBC Processing in an OCC Plant In this case, the collected UBC pulp was subjected to drum pulper and separation based on the concept of a conventional OCC plant. The obtained UBC pulp (shown as sample (6)) was analyzed and the results are shown in Tables 1-2. The results show that the plastic content is relatively high, and the Al and Ca concentrations also remain at high levels.

[0104] Example 7 Comparative - UBC Processing in an OCC Plant As in Example 6, but the pulp was further treated in a heated disperser designed for the treatment of OCC. The resulting UBC pulp (designated as sample (7)) was analyzed and the results are shown in Tables 1-2. A slight improvement in fiber yield and a slight reduction in plastic content were observed. Compared to (6), metal salts are still at high levels, but a slight improvement was observed.

[0105] The solid concentration of this suspension was 7.6% by weight, the SR value was 33, and the WRV value was 163, indicating high drainage resistance. TIFF2024539306000002.tif255164 (Dry basis. % (average weight%) TIFF2024539306000003.tif103170TIFF2024539306000004.tif178170

[0106] Example 8 - 3-ply liquid board manufacturing test The board making trials were carried out on a pilot machine based on Fourdrinier technology with three wires and three headboxes, followed by a press section, drying and surface sizing and calendering section and finally a winding station. Starch was added as ply binder in the amount of 1.8 gsm between the top and middle ply and between the middle and back ply.

[0107] The composition of the pulp mix and layers is given in Table 4 and the test results of the resulting three-ply boards are given in Table 5. The total basis weight of the three-ply boards is 250 g / m 2 The target moisture content was 7.5%.

[0108] Tests with virgin UBC pulp were not performed due to its high bacterial activity, unpleasant odor and high impurity content. Instead, as a reference, high kappa (brown) pulp was used in the middle layer together with blowk (internal furnish, i.e. recycled pulp).

[0109] Example 9 - Bulk pulp from mid-layer UBC The refined UBC pulp obtained in Example 4 was used in a paperboard making test of a three-ply liquid paperboard. The refined UBC pulp was prepared at a solid content of 35% by weight. No off-flavors were observed during the test, and the bacterial activity of this particular pulp was normal under papermaking conditions.

[0110] The total amount of UBC pulp in the board represented 30% of the total board basis weight (fiber), while the percentage in the interlayer was 53%.

[0111] There was a slight decrease in some of the strength properties of the board, but for example the Z strength was still above the benchmark. This example confirms that high yield or high kappa pulp can be substituted for UBC pulp.

[0112] Example 10 - Low amount of pulp from UBC in the middle layer In this case, the composition of the middle layer was changed to mix the UBC pulp with a lower amount and higher content of pulp than in the previous example. The total amount of pulp from UBC in the plate was about 15%. This example confirms that high yield pulp or high kappa pulp can be substituted for UBC pulp.

[0113] Example 11 - Bulk pulp from highly refined UBC In this case, more highly refined pulp from UBC was added to the middle layer (53%) along with broken and high yield pulps. This amount corresponds to a 30% use of UBC Yura pulp in the entire board structure. Despite the high amount of UBC pulp, no effect was observed on the optical or mechanical properties (see Table II). In fact, a significant improvement in Z strength was obtained.

[0114] Example 12 - Small amount of pulp from highly refined UBC In this case, the composition of the middle layer was changed to mix a higher content of high yield pulp with less highly refined pulp from UBC than in the previous example. The total amount of pulp from UBC in the board was about 15%. This example confirms that UBC pulp can be used with a higher content of high yield pulp and does improve some strength properties such as Scott Bond and Z strength. TIFF2024539306000005.tif99170TIFF2024539306000006.tif252170

[0115] Example 13 - Effect of washing and refining on the strength properties of treated UBC pulp The UBC pulps from Examples 1, 4 and 5 were used as starting materials. Three samples of each pulp were prepared, one unrefined and two with two different levels of refinement in a Voith LR40 refiner (4% consistency, 3-1 filler, 0-60°C, specific edge load 2.5 J / m). 160 gsm sheets of each sample pulp were prepared according to standard procedures and the sheets were tested for strength and physical properties. The results are shown in Figures 1-4. In the figures, "RAW UBC" denotes the UBC pulp obtained in Example 1, "UBC+WT" denotes the UBC pulp obtained in Example 4 and "UBC WB" denotes the UBC pulp obtained in Example 5.

[0116] Although impurities and fines are removed during extensive refining and heat treatment of the UBC pulps obtained from Examples 4 and 5, the results surprisingly show that the strength properties of the regenerated and refined pulps can be maintained or improved.

[0117] Unless otherwise specified, the following parameters were measured according to the specified standard methods. Dry matter content: ISO 638 WRV 100 mesh: ISO 23714 Fiber length Lc(l) FS5 ISO:ISO 16065 Drainage resistance (SR): ISO 5267-1 pH: DIN 38404-C5:2009-7 Suspended solids: DIN EN 872:2005-04 BOD:DIN EN 1899-1:1998-05 COD:DIN 38409-H41 / SFS 5504:1988 Total phosphorus: DIN EN ISO 11885:2009-09 Total Nitrogen: DIN EN 25663:1993-11

Claims

1. 1. A method for producing a purified fiber fraction from used beverage cartons (UBC), the method comprising: a) subjecting the UBC starting material to a polymer and aluminum membrane separation process to obtain a UBC polymer and aluminum fraction and a raw UBC fiber fraction; b) optionally subjecting the raw UBC fiber fraction to a coarse screening method to remove coarse particles; c) subjecting the raw UBC fiber fraction to a fine screening process to remove cellulose fines and fine-like materials, the fine screening process comprising at least one fine screening step and at least one dilution step; d) optionally subjecting the fine-screened UBC fiber fraction to a washing process to further remove contaminants; e) optionally subjecting the fine-screened UBC fiber fraction to a bleaching process; f) subjecting the fine-screened and optionally bleached UBC fiber fraction to a dewatering process to a consistency of at least 20% by weight; g) subjecting the dehydrated UBC fiber fraction to inactivation to obtain a purified UBC fiber fraction; A method comprising:

2. 2. The method of claim 1, wherein the UBC starting material in step (a) comprises, on a dry weight basis, at least 15 wt. % plastic and at least 0.3 wt. % aluminum or aluminum compounds, preferably at least 20 wt. % plastic and at least 1 wt. % aluminum or aluminum compounds.

3. 10. The method of claim 1, wherein the UBC starting material in step (a) comprises less than 1 wt. % optical brightener (OBA).

4. 2. The method of claim 1, wherein the raw UBC fiber fraction in step (a) comprises at least 90% by weight of cellulose fibers, preferably at least 95% by weight of cellulose fibers, on a dry weight basis.

5. 2. The method according to claim 1, wherein the purified UBC fiber fraction in step (g) has a Schopper-Riegler (SR) value in the range of 15 to 35, preferably in the range of 18 to 30, determined by standard ISO 5267-1.

6. 2. The method according to claim 1, wherein the purified UBC fiber fraction in step (g) has a water retention value (WRV) determined by standard ISO 23714 in the range of 110-200%, preferably in the range of 120-180%, more preferably in the range of 125-175%.

7. 2. The method of claim 1, wherein the purified UBC fiber fraction in step (g) comprises at least 96% by weight of cellulose fiber, preferably at least 98% by weight of cellulose fiber, on a dry weight basis.

8. 2. The method of claim 1, wherein the purified UBC fiber fraction in step (g) contains less than 0.5 wt. % plastics, preferably less than 0.1 wt. % plastics, based on dry weight.

9. 2. The method of claim 1, wherein the purified UBC fiber fraction in step (g) contains less than 0.5 wt. % aluminum, preferably less than 0.1 wt. % aluminum, based on dry weight.

10. 2. The method of claim 1, wherein the purified UBC fiber fraction in step (g) contains less than 0.1 wt. % OBA, preferably less than 0.05 wt. % OBA, on a dry weight basis.

11. 2. The method of claim 1, wherein the purified UBC fiber fraction in step (g) has an ash content (525°C) of less than 2% and / or an ash content (925°C) of less than 1%.

12. 2. The method of claim 1, wherein the fine screening method of step (c) comprises at least two, preferably at least three screening steps.

13. 2. The method of claim 1, wherein the fine screening method of step (c) comprises at least two, preferably at least three, dilution steps.

14. 2. The method of claim 1, wherein the fine screening and dilution steps of step (c) are repeated at least two, preferably at least three, successive times.

15. 2. The method of claim 1, wherein the fine screening process of step (c) reduces the content of fines in the UBC fiber fraction by at least 20%, preferably by at least 30%, more preferably by at least 40%.

16. 2. The method according to claim 1, wherein the fine screening method of step (c) reduces the content of fines in the UBC fiber fraction by at least 20%, preferably at least 30%, more preferably at least 40%, wherein the content of fines is the content of "FINes A" measured using an FS5 fiber optic analyzer (Valmet).

17. 2. The method of claim 1, wherein the UBC fiber fraction in step (f) is dewatered to a concentration of at least 30% by weight, preferably at least 40% by weight.

18. 2. The method of claim 1, wherein the UBC fiber fraction is subjected to drying at elevated temperature to a concentration of at least 70% by weight, preferably at least 80% by weight, more preferably at least 90% by weight, before, during or after being subjected to the inactivation method.

19. 20. The method of claim 18, wherein drying at elevated temperatures results in denaturation of the UBC fiber fraction.

20. 10. The method of claim 1, wherein the inactivation method of step (g) comprises heat inactivation, chemical inactivation, and / or radiation inactivation.

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