Fibrous product for packaging

Abstract

A fiber product for packaging, particularly food packaging, is presented and described, comprising a first fiber layer. This first fiber layer consists of cellulose-containing fibers and is impregnated with activated carbon in such a way as to reduce the migration of mineral oil hydrocarbons, particularly from the fiber product, into a food product in contact with the fiber product. The fiber product has a chemical oxygen demand of 50 to 1,500 mg / L. Furthermore, a process for producing the fiber product, its use, and the use of activated carbon are described.

Description

[0001] The present invention relates to a fiber product for packaging, in particular food packaging, comprising a first fiber layer. The present invention further relates to a method for producing a fiber product, a use of a fiber product for producing packaging, and the use of activated carbon in a fiber layer of a fiber product for packaging.

[0002] Nowadays, a wide variety of food packaging, as well as other types of packaging, are made from fiber products such as cardboard, carton, and / or paper. Fiber products, also known as fiber-based products, are not only used for packaging but have a broad range of applications. Examples of other products made from fiber products include paper plates, paper cups, and the like. Fiber products contain at least one layer of fibers.

[0003] The fibers in a fiber layer can be cellulose fibers or virgin fibers, waste paper fibers or recycled fibers, or a mixture of both fiber types.

[0004] Fiber products made from paper or cardboard are typically manufactured on paper machines or board machines, where an aqueous fiber suspension is first created in a vat, to which further components can be added. The fiber suspension is then usually passed over a forming section, where most of the water is removed, forming a fiber web. A forming unit or former is typically used in the forming section. In a subsequent press section, the fiber web is often transferred to a press felt and further dewatered by pressure. After the press section, the further dried fiber web usually passes through a drying section and, if necessary, a calender. An important factor for the efficient formation of the fiber web (also referred to as "sheet formation") is the chemical oxygen demand.The chemical oxygen demand (COD) in papermaking often exceeds 4,000 mg / L or even 5,000 mg / L in the vat. Since sheet formation is not always optimal at these COD levels, additives are frequently added to the fiber suspension before the wire section to lower the COD.

[0005] A problem with the use of recycled fibers is the high proportion of newsprint in waste paper, which is generally printed with mineral oil-based inks. Although the recycled fibers are cleaned and treated before reuse, fiber products made from recycled fibers still contain an unavoidable amount of mineral oil hydrocarbons. For example, some fiber products can have a mineral oil hydrocarbon concentration of approximately 100 ppm to 1500 ppm.

[0006] Particularly with food packaging, but also with other products made of fibrous materials that come into contact with food, the problem arises that mineral oil hydrocarbons can migrate from the packaging into the food. However, the ingestion of mineral oil hydrocarbons, especially saturated mineral oil hydrocarbons (MOSH) and / or aromatic mineral oil hydrocarbons (MOAH), through food consumption should be avoided, as even the smallest amounts can cause health problems such as cancer.

[0007] This problem occurs not only with recycled fibers but also with virgin fibers. For example, a large number of individual virgin fiber product packages may be placed inside recycled fiber product packaging for transport. In this case, mineral oil hydrocarbons can migrate from the recycled fiber product packaging first into the virgin fiber product packaging and then into the food. The printing inks used to print the packaging can be a further source of mineral oil hydrocarbons.

[0008] The prior art proposes a solution to the problem by providing the manufactured fiber product with an additional protective layer in a subsequent processing step. For example, US 5,153,061 A discloses a fiber product with a protective layer, such as a polymer coating or an aluminum layer. This protective layer is arranged on the inside of the packaging.

[0009] One disadvantage of this method is that a further processing step is required after the fiber product is manufactured. This increases the manufacturing effort and, consequently, the production costs. Another disadvantage is that, to prevent the migration of mineral oil hydrocarbons into another product, a protective layer of sufficient thickness and covering the entire surface is necessary. However, this layer can be easily damaged, so adequate protection cannot be guaranteed. Furthermore, these protective layers offer no protection at the cut edges, through which the mineral oil hydrocarbons can then escape unhindered.

[0010] WO 2012 / 175309 A1 describes the insertion of activated carbon as a filter material into the fiber layer of a fiber product to reduce the migration of mineral oil hydrocarbons through the fiber layer. However, it has been observed that a fiber product containing activated carbon does not always guarantee sufficient effectiveness, so that in some cases, despite the addition of activated carbon, undesirable levels of residual migration of mineral oil hydrocarbons can be observed. Furthermore, the manufacturing efficiency is not always optimal.

[0011] EP 3 260 597 A1 describes a fibrous product with reduced migration of aromatic hydrocarbons and / or saturated mineral oil hydrocarbons for food packaging compared to fibrous products based on recycled fibers. The fibrous product consists of two or more fibrous layers, and at least one fibrous layer, or an intermediate layer between two fibrous layers, comprises a mineral filter material selected from the group of bentonites and / or saponins. A disadvantage of the fibrous product described in EP 3 260 597 A1 is that the effectiveness of bentonites and saponins is limited.

[0012] Against this background, the present invention aims to provide a fiber product that can be manufactured efficiently and in which the migration of mineral oil hydrocarbons from the fiber product into another product is sufficiently reduced.

[0013] The aforementioned problem is solved according to the invention by a fiber product for packaging, in particular food packaging, comprising a first fiber layer, wherein the first fiber layer has cellulose-containing fibers and is permeated with activated carbon in such a way that the migration of mineral oil hydrocarbons, in particular from the fiber product, into a foodstuff in contact with the fiber product is reduced, wherein the fiber product has a chemical oxygen demand of 50 to 1,500 mg / L.

[0014] The chemical oxygen demand (COD) can be determined, in particular, using a cuvette test. The sample to be measured is placed in a detection solution, heated, and analyzed photometrically. Suitable standardized cuvette tests are known and commercially available. Specifically, cuvettes from Hach Lange GmbH, Düsseldorf, can be used in a so-called Hach LCK cuvette test. Cuvettes are available for different COD ranges. The corresponding cuvettes from Hach Lange GmbH are specifically designed to comply with the standard DIN 38409-H41-H44 (sometimes also referred to as DIN 38409-41 to DIN 38409-44). The measurement is performed by removing a fresh cuvette and shaking it to disperse any sediment. Then, 2.0 mL of the sample to be analyzed is slowly added to the cuvette using a piston-stroke pipette.A filtrate can be used as a sample. The cuvette is then sealed, thoroughly cleaned on the outside, swirled, and heated in a thermostat at 148°C for 2 hours. The hot cuvette is then removed, swirled twice, and cooled to room temperature in a cuvette rack. The cuvette is then thoroughly cleaned on the outside and evaluated by measuring with a Hach photometer, ensuring that any sediment has completely settled before measurement.

[0015] To determine the COD value of the fiber product, the fiber product can be comminuted in water, and then a sample of the resulting fiber suspension or a filtrate thereof can be analyzed. A crusher operating at 3000 rpm can be used to comminute the fiber product. The fiber suspension can have a concentration in the range of 3 to 5 wt%, preferably 4 wt%, based on the total weight of the suspension.

[0016] The chemical oxygen demand is referred to in particular as COD or COD value.

[0017] Surprisingly, it was found that fiber products according to the invention, which have a chemical oxygen demand (COD) of 50 to 1,500 mg / L, can be produced efficiently and effectively reduce the migration of mineral oil hydrocarbons through the fiber product. The COD value of the fiber suspension, which is often in the range of over 4,000 mg / L or over 5,000 mg / L, is lowered by adding additives to improve leaf formation. However, these additives are known to reduce the ability of activated carbon to reduce the migration of mineral oil hydrocarbons. Therefore, it was surprising that the fiber product according to the invention could be produced efficiently and, at the same time, despite the usually necessary addition of additives to adjust the COD value, could effectively reduce the migration of mineral oil hydrocarbons.Without being bound to a scientific theory, activated carbon appears to be less impaired in its function in a demanding fiber product. In particular, at this COD value, activated carbon seems to be less clogged or otherwise hindered by the fibers and any other ingredients, especially additives. At the same time, the fiber products could be manufactured efficiently, which was particularly evident in the good retention.

[0018] A crucial parameter of migrating mineral oils is their chain length. Short-chain mineral oil hydrocarbons (approximately C1 to C9) are generally unproblematic. Without adhering to any scientific theory, it is assumed that they are removed during paper and cardboard production. Very long-chain mineral oil hydrocarbons (approximately above a chain length of C35) are also less problematic due to their generally reduced migration capacity. Mineral oil hydrocarbons with a chain length of C16 to C20 or C16 to C25, however, are particularly problematic.

[0019] In particular, the migration of mineral oil hydrocarbons with chain lengths of C16 to C20 and / or C16 to C25 into food products in contact with the fiber product can be reduced. The migration value can be determined, in particular, according to DIN SPEC 5010:2018-05. The migration test can be carried out, in accordance with DIN SPEC 5010:2018-05, particularly using poly(2,3-diphenyl-p-phenylene oxide) (MPPO) as a simulant. MPPO is also frequently referred to as Tenax. Preferably, the migration test is carried out for a period of 10 days at a temperature of 40°C. The detection and, if necessary, separation of MOSH and MOAH can be carried out, in accordance with DIN SPEC 5010:2018-05, particularly by offline or online coupled HPLC-GC-FID.Cx, for example C16 and C25, denotes in particular the number x of carbon atoms in n-alkanes, whose respective retention times in gas chromatographic separation serve as integration limits for the evaluation of the chromatograms. The integration of the n-alkanes is preferably carried out by including the maximum of the signal.

[0020] With the fiber product according to the invention, the migration of MOSH with a chain length of C 16 to C 20 can be reduced, in particular, to a migration value of 1.5 mg / kg food or less, preferably 1.0 mg / kg food or less, more preferably 0.6 mg / kg food or less. Furthermore, with the fiber product according to the invention, the migration of MOSH with a chain length of C 16 to C 20 can be reduced, in particular, to a migration value of 0.3 mg / dm² or less, preferably 0.2 mg / dm² or less, more preferably 0.1 mg / dm² or less.

[0021] Furthermore, the fiber product according to the invention can reduce the migration of MOAH with a chain length of C 16 to C 25, in particular to a migration value of 0.3 mg / kg food or less, preferably 0.2 mg / kg food or less, and more preferably 0.15 mg / kg food or less. In addition, the fiber product according to the invention can reduce the migration of MOAH with a chain length of C 16 to C 25, in particular to a migration value of 0.05 mg / dm² or less, preferably 0.04 mg / dm² or less, more preferably 0.03 mg / dm² or less, and most preferably 0.025 mg / dm² or less.

[0022] For converting values ​​in mg / dm² to mg / kg of food, the so-called EU cube can be used as a basis, according to which 1 mg / dm² corresponds to 6 mg / kg of food after conversion. The EU cube is familiar to those skilled in the art.

[0023] The food item can be, in particular, a dry food.

[0024] The fiber product can consist of a first fiber layer. The fiber product can comprise further layers, in particular additional fiber layers. Preferably, the fiber product has eight additional fiber layers. The additional fiber layers can also contain activated carbon or be substantially free of activated carbon. For example, the fiber product can have two or three fiber layers impregnated with activated carbon and two or three fiber layers that are substantially free of activated carbon. Preferably, the fiber product has six fiber layers impregnated with activated carbon and three fiber layers that are substantially free of activated carbon.

[0025] The aforementioned problem is further solved according to the invention by a method for producing a fiber product according to the invention, comprising: providing a fiber suspension comprising cellulose-containing fibers and water; adding activated carbon to the fiber suspension to obtain an activated carbon-containing fiber suspension; Producing at least one first fiber layer from the activated carbon-containing fiber suspension using at least one former; wherein the activated carbon-containing fiber suspension has a chemical oxygen demand; wherein the chemical oxygen demand is adjusted to a value of 1,500 to 3,500 mg / L immediately before the former.

[0026] The chemical oxygen demand set in the inventive method is the chemical oxygen demand of the activated carbon-containing fiber suspension.

[0027] The chemical oxygen demand is determined as described above for the fiber product. The fiber suspension, which is then applied to the former, is used as the sample. If necessary, autofiltrate was used to adjust the concentration to 4 wt%.

[0028] The chemical oxygen demand (COD) can be adjusted in various ways known to those skilled in the art. In particular, it can be adjusted by adding additives, especially COD additives. Examples of suitable COD additives include glues, glue fixatives, polymer compounds, stickies, starch, calcium carbonate, potassium carbonate, and kaolin. Examples of glues include alkyl ketene dimers. Examples of polymer compounds include polyacrylamides and polyethyleneimine. Other examples of COD additives include dry hardeners, retention polymers, and aldehydes.

[0029] COD additives can be added in varying amounts. For example, COD additives can be added in an amount of 0.1 to 5 wt.%, preferably 0.5 to 4.5 wt.%, more preferably 1.0 to 4.0 wt.%, and particularly preferably 2.0 to 4.0 wt.%, based on the dry weight of the cellulose-containing fibers.

[0030] According to one embodiment, the fiber product contains 0.1 to 15 wt.%, preferably 0.5 to 10 wt.%, more preferably 1 to 8 wt.%, and particularly preferably 1 to 5 wt.%, activated carbon, in each case based on the dry weight of the fiber product. The dry weight of the fiber product is the air-dry dry weight. "Air-dry" here stands for "air-dry." Preferably, the residual moisture content at air-dry dry weight is 7 to 9 wt.%. With lower amounts of activated carbon, the reduction in migration may be insufficient, especially with heavily stressed fibers. With higher amounts of activated carbon, the resulting fiber product may exhibit undesirable darkening and poorer mechanical properties.

[0031] The fiber product may also contain other additives. Examples of other additives include dyes or pigments.

[0032] Furthermore, the fiber product can have a protective layer. A protective layer, particularly in the form of a coating, is a layer that forms a barrier. This barrier can serve to at least reduce the migration of unwanted substances into an adjacent product. For example, a plastic coating and / or a metal coating can be provided. An additional protective layer can further improve safety. Even though, in principle, the incorporation of activated carbon into the fiber product is sufficient to reduce and, in particular, almost completely prevent the migration of mineral oil substances into another product, it is advantageous to provide an additional protective layer. If, for example, a production error occurs and the fiber product is not impregnated with activated carbon, the fiber product can still be used without concern due to the additional protective layer.

[0033] In principle, the protective layer can be arranged at any position on the fiber product. A simple and particularly efficient embodiment exists when the fiber product has an outer layer, which is specifically designed as a protective layer. An outer protective layer can be applied to the top or bottom surface. In particular, the layer of the fiber product intended for contact with the product to be packaged can be designed as a protective layer. The protective layer can comprise suitable plastic and / or metallic materials that at least reduce the amount of migrating mineral oil hydrocarbons from the fiber product. Advantageously, the protective layer can also be designed to prevent the release of activated carbon from a fiber layer. Preferably, the fiber product according to the invention does not have a protective layer.

[0034] The invention also relates to the use of a fiber product according to the invention for the production of packaging, in particular food packaging, with reduced migration of mineral oil hydrocarbons into a food product in contact with the fiber product.

[0035] The aforementioned problem is further solved according to the invention by the use of activated carbon in a fiber product for packaging to reduce the migration of mineral oil hydrocarbons, in particular from the fiber product, into a foodstuff in contact with the fiber product, wherein the fiber product has a chemical oxygen demand of 50 to 1,500 mg / L. The fiber product is preferably a fiber product according to the invention.

[0036] Advantageously, the activated carbon has an iodine value of 800 mg / g or more, preferably 1,000 mg / g or more, and more preferably 1,200 mg / g or more. Activated carbon with such iodine values ​​has a high specific surface area and is therefore particularly suitable for reducing mineral oil hydrocarbons. Activated carbon with an iodine value below 800 mg / g can also be used for the invention; however, this is disadvantageous because additional amounts of activated carbon must then be used to achieve a sufficient reduction in the migration of mineral oils through the fiber product. The iodine value of activated carbon can be determined, in particular, according to the standard ASTM D:4607-2014.

[0037] The invention relates to a food packaging comprising a fiber product according to the invention. Preferably, the food packaging is made from the fiber product according to the invention. The food packaging is preferably for dry foods. The food is preferably in contact with the food packaging.

[0038] The following describes various embodiments of the fiber product, the process, and the uses, each embodiment being independent of the other. Furthermore, the individual embodiments can be combined with one another as desired.

[0039] In one embodiment, the fiber product has a cationic requirement of 0.1 to 3 mL, preferably 0.5 to 3 mL, more preferably 0.5 to 2.5 mL, and particularly preferably 1 to 2.4 mL.

[0040] The cationic requirement refers to the amount of polyDADMAC titration solution. Preferably, a cationic polyDADMAC solution with a known concentration of, for example, 20% w / v or 0.001 N, or preferably 0.001 N, polyDADMAC in water is used as the titration solution. PolyDADMAC stands for polydiallyldimethylammonium chloride. The cationic requirement is determined as the amount of polyDADMAC solution needed to neutralize a suspension of the fiber product in water. The titration can be performed, for example, using the Mütek PCD-05 instrument from BTG Instruments AB, Säffle, Sweden. A 300-mesh sieve from BTG Instruments AB is preferably used for sample preparation. A sample volume of 10 mL is preferably used. Titration solutions from BTG Instruments AB are preferably used.The cationic requirement of the fiber product or fiber suspension or activated carbon-containing fiber suspension specified herein refers in particular to a measurement using a titration solution of 0.001 N, PolyDADMAC in water on a sample of 10 mL.

[0041] To determine the cationic demand of the fiber product, the fiber product can be comminuted in water, and then a sample of the resulting fiber suspension or a filtrate thereof can be analyzed. Preferably, the sample preparation is carried out as described for the determination of the COD value. The fiber suspension can have a concentration in the range of 3 to 5 wt%, preferably 4 wt%, based on the total weight of the suspension.

[0042] In one embodiment, the fiber product has a basis weight of 50 to 1,000 g / m², preferably 80 to 800 g / m², more preferably 80 to 600 g / m², and particularly preferably 100 to 500 g / m². The basis weight is preferably determined according to DIN EN ISO 536, in particular DIN EN ISO 536:2020-05. The basis weight is preferably the net basis weight.

[0043] If the fiber product consists of several fiber layers, the individual fiber layers preferably each have a basis weight of 30 to 150 g / m². Fiber layers impregnated with activated carbon can, in particular, have a basis weight of 80 to 150 g / m².

[0044] The fiber products according to the invention have the advantage that they sufficiently prevent the migration of mineral oil hydrocarbons even at a low basis weight of < 50 g / m². Furthermore, by using activated carbon, the migration of mineral oil hydrocarbons can also be sufficiently reduced in fiber products with a basis weight of up to < 1,000 g / m², provided a suitable COD value is achieved.

[0045] In one embodiment of the fiber product, the cellulose-containing fibers in the fiber product have a zeta potential of -8 to -22 mV, preferably -10 to -21 mV, more preferably -11 to -20 mV, and particularly preferably -12 to -19 mV.

[0046] The experiments that led to the invention revealed that a fiber product according to the invention, in which the cellulose-containing fibers have a zeta potential as specified above, effectively prevents the migration of mineral oil hydrocarbons through the fiber product. Without being bound to any scientific theory, activated carbon in a fiber product with this zeta potential does not appear to be impaired in its function. In particular, at this zeta potential, activated carbon does not appear to be covered or otherwise hindered by the fibers and any other ingredients.

[0047] To determine the zeta potential of the cellulose-containing fibers in the fiber product, the fiber product can be comminuted in water, and then a sample of the resulting fiber suspension or a filtrate thereof can be analyzed. Preferably, the sample preparation is carried out as described for the determination of the COD value. The fiber suspension can have a concentration in the range of 3 to 5 wt%, preferably 4 wt%, based on the total weight of the suspension.

[0048] The zeta potential can be determined, in particular, using the Mütek SZP-06 instrument from BTG Instruments AB, Säffle, Sweden. The measurement is preferably carried out with a 500 mL sample. The sample preferably has a consistency of 3 to 5 wt%, preferably 4 wt%, optionally diluted with its own filtrate if the consistency is higher. The conductivity can be measured in parallel.

[0049] In one embodiment, the fiber product has a chemical oxygen demand of 50 to 1,200 mg / L, preferably 100 to 1,000 mg / L, more preferably 200 to 900 mg / L, and particularly preferably 300 to 800 mg / L.

[0050] The experiments that led to the invention showed that the migration of mineral oil hydrocarbons through the fiber product can be effectively prevented if the chemical oxygen demand (COD) of the fiber product is within the claimed range. Without wishing to be bound to a scientific theory, this is currently attributed to the fact that, at the aforementioned COD values, activated carbon appears to be even less affected by the fibers and any other constituents, or otherwise impeded. At the same time, the fiber product could be manufactured economically.

[0051] The fiber product can be in various forms. In one embodiment, the fiber product is cardboard, carton, and / or paper.

[0052] In one embodiment, it is preferred that the cellulose-containing fibers comprise or consist of virgin fibers, recycled paper fibers, or a mixture of virgin fibers and recycled paper fibers.

[0053] Waste paper fibers, also called recycled fibers, can be made from waste paper. It is understood that the waste paper fibers may have been cleaned. While cleaning the waste paper fibers reduces the mineral oil content, it does so insufficiently. Only the addition of activated carbon and the treatment of the fibers according to the invention ensure that the migration of mineral oil hydrocarbons can be sufficiently reduced.

[0054] Virgin fibers are, for example, fibers made from cellulose. Depending on the application of the fiber product and / or the desired properties of the at least one fiber layer, the first fiber layer can consist exclusively of virgin fibers, exclusively of recycled paper fibers, or of both types of fibers in a predefined ratio.

[0055] According to one embodiment, the cellulose-containing fibers comprise 20 wt.% or more, preferably 40 wt.% or more, more preferably 60 wt.% or more, even more preferably 80 wt.% or more, and particularly preferably 95 wt.% or more, recycled paper fibers, based on the total weight of the cellulose-containing fibers. The use of higher recycled fiber content is particularly advantageous from an environmental perspective.

[0056] The problem mentioned at the outset is solved, as explained above, by the inventive method for producing a fiber product according to the invention, as described above.

[0057] Preferably, in the process according to the invention, the chemical oxygen demand of the fiber suspension is adjusted to a value of 1,800 to 3,000 mg / L, more preferably 2,000 to 3,000 mg / L, and particularly preferably 2,000 to 2,800 mg / L, immediately before the former.

[0058] In one embodiment of the method, the cationic requirement of the activated carbon-containing fiber suspension is adjusted to a value of 0.01 to 3 mL, preferably 0.10 to 2.5 mL, more preferably 0.5 to 2 mL, immediately before the former.

[0059] The cationic requirement is determined as described above for the fiber product. The fiber suspension, which is then applied to the former, is used as a sample. If necessary, autofiltrate was used to adjust the concentration to 4 wt%.

[0060] The cationic requirement of the fiber product can be adjusted in various ways known to those skilled in the art. For example, it can be adjusted by adding activated carbon. Furthermore, the cationic requirement can be adjusted by adding fixatives. Examples of suitable fixatives are alum, aluminum sulfate, polyethyleneimine, polyDADMAC, silica, starch (cationic or native), and sizing agents, such as alkyl ketene dimer glue (AKD glue), alkyl succinic anhydride glue (ASA glue), or adhesive glue.

[0061] The aforementioned fixing agents can be added at various points in the fiber product manufacturing process. For example, the fixing agents can be added to the fiber suspension in the vat. If activated carbon is added to the fiber suspension, the fixing agents can be added before and / or after the activated carbon, particularly in the vat. Furthermore, fixing agents can also be added after the vat, for example, immediately before the former.

[0062] Fixing agents can be added in varying amounts. For example, fixing agents can be added in amounts ranging from 0.01 to 5% by weight, particularly 0.1 to 4% by weight, based on the dry weight of the cellulose-containing fibers of the first fiber layer.

[0063] In one embodiment of the process, the zeta potential in the activated carbon-containing fiber suspension is adjusted immediately before the former such that the cellulose-containing fibers have a zeta potential of -15 to -1 mV, preferably -12 to -2 mV, more preferably -10 to -3 mV, and particularly preferably -8 to -4 mV.

[0064] The zeta potential is determined as described above for the fiber product. The fiber suspension, which is then applied to the former, is used as the sample. If necessary, autofiltrate was used to adjust the concentration to 4 wt%.

[0065] The zeta potential of the activated carbon mixture can be adjusted by adding zeta additives. Examples of suitable zeta additives are the same as those used to meet cationic requirements.

[0066] Zeta additives can be added in varying amounts. For example, zeta additives can be added in amounts ranging from 0.01 to 5 wt%, particularly 0.1 to 4 wt%, based on the dry weight of the cellulose-containing fibers.

[0067] In one embodiment of the method, an adhesive is added to the fiber suspension or the activated carbon-containing fiber suspension.

[0068] Various adhesives are known to those skilled in the art. In particular, the adhesive may be selected from the group consisting of resin adhesives, synthetic adhesives such as alkyl ketene dimer adhesives (AKD adhesives) or alkyl succinic anhydride adhesives (ASA adhesives).

[0069] In one embodiment of the invention, the fiber product can be produced with a retention of 45% or more, preferably 50% or more. The retention is calculated, in particular, as the percentage ratio of the mass of the obtained fiber product to the amount of raw material, additives, and fixing agents used.

[0070] Further features and advantages of the fiber product, the process and its uses will become apparent from the following description of exemplary embodiments. EXAMPLES Example 1: Reduction of mineral oil migration in a fiber product with a set chemical oxygen demand

[0071] Cardboard for food packaging was manufactured as a fiber product. This cardboard consisted of nine fiber layers, six of which were inner layers impregnated with activated carbon and bonded together. These six inner fiber layers with activated carbon are referred to below as the core. The cardboard also had a top layer, a protective layer, and a back layer, each free of activated carbon. Various cardboard types were produced, with only the core being varied. The fiber layers that did not form the core were produced from a fiber suspension without activated carbon in a manner known to those skilled in the art, using the usual additives and auxiliaries. The cardboard had a basis weight of 350 g / m² according to DIN EN ISO 536:2020-05. The front side had two pigment coatings, and the back side had one pigment coating.The pigment coating consisted of a commercially available carbonate / kaolin mixture.

[0072] The inserts were produced as follows. First, a fiber suspension consisting of cellulose-containing fibers and water was prepared in a separate vat for each insert. The cellulose-containing fibers in the fiber suspension for both the insert and the cover, protective, and backing layers were each a mixture of recycled paper fibers.

[0073] To the fiber suspensions used for the inserts, an aqueous suspension containing activated carbon with an iodine value of approximately 1050 mg / g was added in varying amounts, as shown in Table 1 below, based on the dry weight of the cardboard, including fiber products as a control that did not contain activated carbon. Depending on the requirements of the cellulose-containing fibers, one or more additives were added to the various fiber suspensions. The chemical oxygen demand (COD) of the fiber suspension in the vat was approximately 4500 mg / L. One or more of the following additives were used to adjust the COD: alum, aluminum sulfate, polyacrylamide, polyvinylamine, polyethyleneimine, polyDADMAC, starch, calcium carbonate, potassium carbonate, kaolin, silica, AKD sizing, and ASA sizing. Polyacrylamide and polyvinylamine were the most commonly used.The layers of the insert were produced from the mixtures, with the COD value of the activated carbon-containing fiber suspension being adjusted to approximately 2,500 mg / L by adding polyacrylamide immediately before the former. The respective inserts were then bonded with the remaining layers to form a nine-layer cardboard unit.

[0074] The COD value was determined using the Hach LCK cuvette test, employing LCK014 cuvettes from Hach Lange GmbH, Düsseldorf. A fresh cuvette was removed and shaken to suspend any sediment. Then, 2.0 mL of the sample was slowly added to the cuvette using a piston-stroke pipette.

[0075] To determine the COD value in the vat, a sample of the fiber suspension was taken from the vat, and the solids content of the fiber suspension was adjusted to 4% as needed. For dilutions, the sample was taken from the sample itself. The fiber suspension was then filtered using a 100-mesh sieve. The filtrate was subsequently added to the cuvette as a sample.

[0076] To determine the COD value immediately before the former, a sample of the fiber suspension was taken after the addition of polyacrylamide, directly before the former, and the solids content of the sample was adjusted to 4% as needed. For dilutions, the sampled filtrate was used. This sample was also filtered using a 100-mesh sieve. The filtrate was then added to the cuvette as the sample.

[0077] To determine the COD value of the cardboard, an 80 g sample of dried (lutro) cardboard was ground into a fiber suspension using a Frank-PTI GmbH, Birkenau, blended with 2000 mL of distilled water. If necessary, the concentration of the resulting fiber suspension was adjusted to 4 wt% using the intrinsic filtrate. This suspension was then filtered through a 100-mesh sieve from BTG Instruments AB. The filtrate was subsequently added to the cuvette as the sample.

[0078] The cuvette was then sealed, thoroughly cleaned on the outside, swirled, and heated in a thermostat at 148°C for two hours. The hot cuvette was then removed, swirled twice, and cooled to room temperature in a cuvette rack. Afterward, the cuvette was thoroughly cleaned on the outside and analyzed using a Hach photometer, ensuring that any sediment had completely settled before measurement.

[0079] The cardboard was dried and then tested for migration according to DIN SPEC 5010:2018-05. MPPO was used as a food simulant for the migration test. The migration test was carried out for 10 days at a temperature of 40°C. The detection and, where necessary, separation of MOSH and MOAH was performed according to DIN SPEC 5010:2018-05 using online-coupled HPLC-GC-FID and determined for the chain lengths of the n-alkanes C16 to C20 and C16 to C25, with the integration of the n-alkanes including the signal maxima. The determined migration values ​​for MOSH compounds and MOAH compounds were calculated separately and are listed in Table 1. Table 1: Migration values ​​and COD values sample COD value [mg / L] Percentage of activated carbon b < [wt.%] Retention c< [%] MOSH d< [mg / kg food] MOAH e< [mg / kg food] 1 490 1 55 1,5 0,49 2 600 2 50 0.6 or less 0.15 or less V1 f< 530 0 57 40 51 V2 f< 1970 2 30 0.6 or less 0.15 or less Explanations for Table 1: a< - Determined chemical oxygen demand of the carton; b< - Determined proportion of activated carbon in the carton, based on the dry weight (lutro) of the carton; c< - Retention of the insert, based on the amount of raw material used as well as additives and fixatives; d< - Migration value for MOSH with a chain length of C16-C20, determined as described above using Tenax; e< - Migration value for MOAH with a chain length of C16-C25, determined as described above using Tenax; f< - Comparison example.

[0080] The experiment shows that fiber products according to the invention, which have a chemical oxygen demand of 50 to 1,500 mg / L, reduce the migration of mineral oils such as MOSH and MOAH more effectively than conventional fiber products with an oxygen demand outside this range and can be manufactured well at the same time. Example 2: Reduction of mineral oil migration in a fiber product with a set cationic demand

[0081] A cardboard fiber product was manufactured according to the process described in Example 1, with the exception that the cationic requirements of the fiber product were also adjusted. For this purpose, polyacrylamide or polyvinylamine was added to the various fiber suspensions. Depending on the raw material of the cellulose-containing fibers, an alternative fixing agent can be selected from alum, aluminum sulfate, polyethyleneimine, polyDADMAC, starch, calcium carbonate, potassium carbonate, kaolin, silica, AKD glue, or ASA glue. Immediately before the former, the cationic requirements of the activated carbon-containing fiber suspension were adjusted to a value of 1 mL to 3 mL by adding polyacrylamide.

[0082] The cationic demand of the fiber product was determined by titration using a 0.001 N PolyDADMAC solution from BTG Instruments AB until neutralization. First, a 4% fiber suspension was prepared from the cardboard, following the same procedure as described in Example 1 for determining the COD value of the cardboard. This suspension was then filtered using a 300-mesh sieve from BTG Instruments AB. The filtrate was subsequently analyzed as a sample of the fiber product. The titration was performed using a Mütek PCD-05 instrument from BTG Instruments AB, Säffle, Sweden. A sample volume of 10 mL was used.

[0083] The migration test described in Example 1 was performed on the cardboard. Migration values ​​for MOSH compounds and MOAH compounds were determined separately and are listed in Table 2. Table 2: Cationic demand and migration values sample Cationic requirement a< [mL] Percentage of activated carbon b < [wt.%] Retention c< [%] MOSH d< [mg / kg food] MOAH e< [mg / kg food] 3 1,3 1 55 1,5 0,49 4 1,0 2 50 0.6 or less 0.15 or less V3 f< 1,5 0 57 40 51 V4 f< 3,5 2 40 0.6 or less 0.15 or less Explanations for Table 2: a< - Determined cationic requirement of the carton; b< - Determined proportion of activated carbon in the carton, based on the dry weight (lutro) of the carton; c< - Retention of the insert, based on the amount of raw material used as well as additives and fixatives; d< - Migration value for MOSH with a chain length of C16-C20, determined as described above using Tenax; e< - Migration value for MOAH with a chain length of C16-C25, determined as described above using Tenax; f< - Comparison example.

[0084] The experiment shows that fiber products with a cationic need in the required range reduce the migration of mineral oils such as MOSH and MOAH more effectively than conventional fiber products outside the range, while still being manufactured with good retention. Example 3: Reduction of mineral oil migration in a fiber product with a set zeta potential

[0085] A cardboard fiber product was manufactured according to the process described in Example 1, with the exception that the zeta potential of the fiber product was also adjusted. For this purpose, at least one zeta additive selected from alum, aluminum sulfate, polyacrylamide, polyvinylamine, polyethyleneimine, polyDADMAC, starch, calcium carbonate, potassium carbonate, kaolin, silica, AKD sizing, or ASA sizing was added to the various fiber suspensions, depending on the raw material of the cellulose-containing fibers. Polyacrylamide or polyvinylamine was most commonly added. Immediately before the former, the zeta potential of the cellulose-containing fibers in the activated carbon-containing fiber suspension was adjusted to a value of -8 to -4 mV by adding polyacrylamide.

[0086] The zeta potential of the fiber product was determined using the Mütek SZP-06 instrument from BTG Instruments AB, Säffle, Sweden. First, a 4% fiber suspension was prepared from the cardboard, following the same procedure as in Example 1 for determining the COD value of the cardboard. However, unlike the sample preparation for determining the COD value of the cardboard, the sample was not filtered. Instead, 500 mL of the 4% fiber suspension was used. If necessary, it was diluted with filtrate from the fiber suspension.

[0087] The migration test described in Example 1 was performed on the cardboard. Migration values ​​for MOSH compounds and MOAH compounds were determined separately and are listed in Table 3. Table 3: Zeta potential and migration values sample Zeta potential a< [mV] Percentage of activated carbon b < [wt.%] Retention c< [%] MOSH d< [mg / kg food] MOAH e< [mg / kg food] 5 -13 1 55 3,60 0,25 6 -17 2 50 2,5 0,50 V5 f< -13,3 0 57 40 51 V6 f< -23 2 41 0.6 or less 0.15 or less Explanations for Table 3: a< - Determined zeta potential of the cardboard; b< - Determined proportion of activated carbon in the cardboard, based on the dry weight (lutro) of the cardboard; c< - Retention of the insert, based on the amount of raw material used as well as additives and fixatives; d< - Migration value for MOSH with a chain length of C16-C20, determined as described above using Tenax; e< - Migration value for MOAH with a chain length of C16-C25, determined as described above using Tenax; f< - Comparison example.

[0088] The experiment shows that fiber products with a zeta potential in the required range reduce the migration of mineral oils such as MOSH and MOAH more effectively than conventional fiber products with a zeta potential outside this range, and can also be manufactured well.

Claims

1. Fibre product for packaging, in particular food packaging, comprising a first fiber layer, wherein the first fiber layer comprises cellulose-containing fibers and is impregnated with activated carbon in such a way as to reduce the migration of mineral oil hydrocarbons, in particular from the fiber product, into a foodstuff in contact with the fiber product, characterized by the fact that The fiber product has a chemical oxygen demand of 50 to 1,500 mg / L.

2. Fiber product according to claim 1, characterized by the fact that The fiber product has a cationic requirement of 0.1 to 3 mL, preferably 0.5 to 3 mL, more preferably 0.5 to 2.5 mL, and particularly preferably 1 to 2.4 mL.

3. Fiber product according to claim 1 or 2, characterized by the fact that The fiber product has a basis weight of 50 to 1,000 g / m² 2 preferably from 80 to 800 g / m² 2 , preferably from 80 to 600 g / m² 2 , particularly preferably from 100 to 500 g / m² 2 , exhibits.

4. Fiber product according to any one of claims 1 to 3, characterized by the fact that the cellulose-containing fibers in the fiber product have a zeta potential of -8 to -22 mV, preferably -10 to -21 mV, more preferably -11 to -20 mV, particularly preferably -12 to -19 mV.

5. Fiber product according to any one of the preceding claims, characterized by the fact that The fiber product has a chemical oxygen demand of 50 to 1,200 mg / L, preferably 100 to 1,000 mg / L, more preferably 200 to 900 mg / L, and particularly preferably 300 to 800 mg / L.

6. Fiber product according to any one of the preceding claims, characterized by the fact that The fiber product is cardboard, carton and / or paper.

7. Fiber product according to any one of the preceding claims, characterized by the fact that the cellulose-containing fibers comprise or consist of virgin fibers, recycled paper fibers or a mixture of virgin fibers and recycled paper fibers.

8. Fiber product according to any one of the preceding claims, characterized by the fact thatthe cellulose-containing fibers comprise 20 wt.% or more, preferably 40 wt.% or more, further preferably 60 wt.% or more, even more preferably 80 wt.% or more, particularly preferably 95 wt.% or more, recycled paper fibers, based on the total weight of the cellulose-containing fibers.

9. A method for producing a fiber product according to any one of claims 1 to 8, comprising: providing a fiber suspension comprising cellulose-containing fibers and water; adding activated carbon to the fiber suspension to obtain an activated carbon-containing fiber suspension; producing at least one first fiber layer from the activated carbon-containing fiber suspension using at least one former; wherein the activated carbon-containing fiber suspension has a chemical oxygen demand; wherein the chemical oxygen demand is adjusted to a value of 1,500 to 3,500 mg / L immediately before the former.

10. Method according to claim 9, characterized by the fact thatThe cationic requirement of the activated carbon-containing fiber suspension is adjusted to a value of 0.01 to 3 mL, preferably 0.10 to 2.5 mL, more preferably 0.5 to 2 mL, immediately before the former.

11. Method according to one of claims 9 or 10, characterized by the fact that the zeta potential in the activated carbon-containing fiber suspension is adjusted immediately before the former such that the cellulose-containing fibers have a zeta potential of -15 to -1 mV, preferably -12 to -2 mV, more preferably -10 to -3 mV, particularly preferably -8 to -4 mV.

12. Method according to any one of claims 9 to 11, characterized by the fact that A glue is added to the fiber suspension or the activated carbon-containing fiber suspension.

13. Use of a fiber product according to any one of claims 1 to 8 for the manufacture of packaging, in particular food packaging, with reduced migration of mineral oil hydrocarbons into a foodstuff in contact with the fiber product.

14. Use of activated carbon in a fiber layer of a fiber product for packaging to reduce the migration of mineral oil hydrocarbons, in particular from the fiber product, into a foodstuff in contact with the fiber product, wherein the fiber product has a chemical oxygen demand of 50 to 1,500 mg / L.

15. Use according to claim 14, characterized by the fact that the fiber product is a fiber product according to any one of claims 1 to 8.

16. Food packaging comprising a fiber product according to any one of claims 1 to 8.

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