EP4150153A1

EP4150153A1 - Paper packaging material having improved resuspendability of the cellulose fibres

Info

Publication number: EP4150153A1
Application number: EP21726570.1A
Authority: EP
Inventors: Achim Grefenstein; Markus Kick; Matthias Scheck; Thomas Kesmarszky
Original assignee: Constantia Pirk GmbH and Co KG
Current assignee: Constantia Pirk GmbH and Co KG
Priority date: 2020-05-11
Filing date: 2021-05-06
Publication date: 2023-03-22
Also published as: WO2021228695A1; US20230130087A1; DE102020112672A1

Abstract

The invention relates to a paper-based packaging material having a carrier paper and a first coating arranged indirectly at least on one side of the carrier paper, wherein the first coating is a barrier layer and has an increased diffusion resistance at least to a substance selected from a group comprising fluid, gas, air, oxygen, carbon dioxide, nitrogen, inert gas, odourant, flavouring, water vapour, liquid, water, water-fat emulsion, fat, oil, mineral oil and edible oil individually or in combination, wherein the first coating is arranged between the carrier paper and a visually perceivable surface coating and is in direct contact with the surface coating. The invention also relates to a packaging consisting of such a paper-based packaging material and to a method for the production of same.

Description

Paper packaging material with improved resuspension of the cellulose fibers

description

The present invention relates to a paper-based packaging material with a carrier paper and a first coating arranged indirectly on at least one side of the carrier paper, wherein the first coating can be a barrier layer and at least for one substance selected from a group consisting of fluid, gas, Air, oxygen, carbon dioxide, nitrogen, inert gas, odorous substance, aromatic substance, water vapor, liquid, water, water-fat emulsion, fat, oil, mineral oil (MOSH (Mineral Oil Saturated Hydrocarbons or saturated mineral oil hydrocarbons) MOAH (Mineral Oil Aromatic Hydrocarbons ), POSH (polyolefinic saturated hydrocarbons) or aromatic mineral oil hydrocarbons)) and edible oil individually or in combination, has an increased diffusion resistance. The invention further relates to a packaging made of such a paper-based packaging material and a method for its manufacture. Various different packaging solutions are known from the prior art. Packaging for food is of particular importance, as special requirements are placed on the packaging materials used for it. In order to meet the requirements in terms of hygiene, printability and barrier properties for contamination, food has so far mainly been packed in plastic packaging. With regard to the problems associated with the use of plastics for packaging of insufficient recyclability, the pollution from thermal recycling and poor degradability, efforts are made to replace plastics with alternative materials. This endeavor has been intensified, in particular by the current discussion of plastic residues in the world's oceans and microplastics in the environment. Therefore, attempts have been made in the past to produce packaging for food from paper. In order to be able to meet the above requirements with regard to the barrier properties, the papers were coated. However, the resulting paper laminates are generally difficult to recycle because the barrier layers shield the carrier paper in such a way that the cellulose fibers of the paper are difficult to access during the recycling process. The recycling process must therefore be operated with increased effort, which, however, counteracts the efforts to conserve resources. Under the usual conditions of the recycling process, such paper laminates therefore remain as large-format residues. The suspension of the cellulose fibers contained in the paper laminate in the pulp is only possible to a limited extent, if at all. The fiber content in the pulp is preferably 50%.

There is therefore a need for paper-based packaging material that meets the requirements of the food industry in terms of properties as a packaging material and, on the other hand, is also recyclable. In particular, the cellulose fibers of the paper should be resuspendable in such a way that they pass into the pulp.

There is also a need for a method for producing such a paper-based packaging material.

Paper-based packaging that can be recycled using existing processes and systems is also desirable.

These objects are achieved by the subjects of the independent claims.

A paper-based packaging material according to the invention comprises a carrier paper and a first coating arranged indirectly on at least one side of the carrier paper. It is preferably a paper packaging material for food containers. However, other uses are not excluded. The first coating can be a Be a barrier layer and thus has a diffusion resistance that is higher than that of paper, at least for one substance. The substance is selected from a group consisting of fluid, gas, air, oxygen, carbon dioxide, nitrogen, inert gas, odorous substance, aromatic substance, water vapor, liquid, water, water-fat emulsion, fat, oil, mineral oil (MOSH (Mineral Oil Saturated hydrocarbons or saturated mineral oil hydrocarbons), MOAH (Mineral Oil Aromatic Hydrocarbons or aromatic mineral oil hydrocarbons), POSH (polyolefinic saturated hydrocarbons) and edible oil individually or in combination. This makes it possible for this substance not to diffuse, or only with a delay, through the paper or through the packaging. In this context, it is particularly important to reduce the diffusion of MOSH, fat, oxygen and water vapor (individually or in combination) through the packaging material. The penetration of undesired substances through the packaging to the product can thus be prevented or delayed. It is also possible to reduce or prevent substances from escaping from the product through the packaging material and into the environment. In this way, for example, an exchange of a gas atmosphere from an inert gas atmosphere to an oxygen-containing atmosphere inside the packaging can be prevented and the oxidation of the product can thus be delayed.

In the context of this invention, an increased diffusion resistance for one of the substances mentioned above is to be understood as meaning that the diffusion resistance of the barrier layer for this substance is at least by a factor> 1.5, preferably> 2, more preferably> 3, in particular is preferably> 5 and particularly preferably> 10 greater than the diffusion resistance of Kraft paper (in particular of the carrier paper) for this substance.

It is also conceivable to prevent the penetration of moisture in the form of water or water vapor in order to prevent or slow down the softening or clumping of the product. Another important application is preventing or delaying the diffusion of fat and / or oil through the packaging. Particularly in the case of foods containing fat and / or oil, the diffusion of fat and / or oil through the packaging causes it to have visually recognizable oil or fat stains and is thus perceived by the customer as unsightly or even unsavory. It is therefore essential to the invention that the first coating is arranged between the carrier paper and an optically perceptible surface coating and that the surface coating is in direct contact. This arrangement makes it possible, for example, that the substance which is diffusion-inhibited by the first layer can indeed diffuse into the carrier paper, but cannot escape from the carrier paper on the opposite side through the first coating. The surface coating arranged with respect to the first coating on the side opposite the carrier paper is thus effectively protected from contact with this substance. This means that contamination by this substance does not occur or only occurs with a significant delay.

A significant advantage of the arrangement described above is, however, that when recycling such a paper-based packaging material, the carrier paper has neither the first coating (or the barrier layer) nor the surface coating on one side, which could prevent the solvent from accessing the paper. It can thus be ensured that these coatings do not hinder the transition of cellulose fibers from the carrier paper into the pulp, at least from one side. The solvent (for example water) can thus penetrate to the carrier paper on one side without being hindered by the first coating (or the barrier layer) or the surface coating, wet it and dissolve cellulose fibers from the fiber composite of the carrier paper.

A visually perceptible surface coating in the sense of the present invention is to be understood as any coating that is visually perceptible on this side of the packaging material by a person (for example a customer). It is not absolutely necessary that this optically perceptible surface coating actually (neither in sections nor over the entire area) represents an outer surface of the packaging material. Rather, the optically perceptible surface coating could be, for example, a monochrome or colored print. This could also be covered by a further layer, preferably an at least partially transparent layer. For example, such a layer could be a lacquer.

In contrast to the paper-based packaging materials known from the prior art, the carrier paper is therefore not between the first coating (or the barrier Layer) and the surface coating that is visually perceptible to the customer, which would make it more difficult for the solvent to access the carrier paper from both sides. The disadvantageous delayed wetting of the carrier paper resulting therefrom and thus also the detachment of cellulose fibers can be avoided or at least drastically accelerated.

The first coating does not necessarily have to be arranged directly on the carrier paper, although this is preferred. It would be conceivable for an intermediate layer to be arranged between the carrier paper and the first coating, for example a print which is covered by a transparent first coating. A primer or a further barrier layer (which represents a (temporary) barrier for another substance, for example) would also be conceivable.

In a preferred embodiment, the first layer of the paper-based packaging material comprises at least one layer which is selected from a group consisting of a moisture barrier, oxygen barrier, gas barrier, mineral oil barrier, aroma barrier, UV barrier, light barrier, fat diffusion barrier, fat sealing layer, sealing layer and adhesive layer. By means of such a layer, the paper laminate can be adjusted to the respective requirements of the product, especially in the packaging industry.

The first coating is preferably a barrier coating. For example, this is selected from a group comprising PVDC coating, PVOH coating, PVOH-based coating and acrylate-based coating. In the case of a PVOH-based coating, this coating can be embedded between two further coatings that are diffusion-inhibiting for moisture, e.g. B. Polybutylene succinate (PBS). Sizing agents or water repellants based on the following are preferred, preferably cationic or cationized resin dispersions and resin-aluminum salt dispersions (whereby polyaluminum chloride (PAC) is particularly suitable as a cationic fixing agent in combination with polymeric retention agents for higher pH values) , preferably AKD (alkenyl ketene dimer) dispersions, more preferably stabilized with cationic starch as protective colloid and cationic polymers as fixing agent or promoter, particularly preferably ASA (Alkenyl Succinic Anhydride, dt .: Alkenyl- Succinic anhydride dispersions more preferably with cationic starch as a stabilizer (to an increasing extent). Cationic or anionic ones are also preferred Fluorocarbon resins or polyvinylidene chloride (PVDC) coating and preferably carboxymethyl cellulose (CMC).

These coatings are preferred because of their barrier properties and ease of processing. These barrier layers can be arranged one above the other in such a way that the individual layers are optionally constructed chemically equivalent or chemically non-equivalent. If necessary, it is preferred that the barrier coating comprises inorganic oxides such as aluminum oxide or silicon oxide. In particular, it is preferred that the barrier coating contains inorganic fillers, such as preferably a silicon-containing substance, which is more preferably powdery. It is particularly preferred that the powder (d ₅ o, Sedigraph) having an average particle size, the <10 gm, preferably <3 gm and be sondere preferably <1 pm is. In addition to or independently of the size, it is preferred that the powder is three-dimensionally cross-linked with high density in a polymer. As an alternative or in addition to this, the above-mentioned oxides could also be applied as a separate layer by vapor deposition. The layer thickness for these oxides is preferably from 0.01 μm to 0.5 μm. As an alternative or in addition to this, for some embodiments it is also possible to deposit several metals, preferably at least one metal. If metallized surfaces are desired, the deposition of aluminum is preferred. The layer thickness for aluminum is preferably 0.008 pm-0.5 pm, preferably 0.01 pm-0.1 pm. Instead of a metal, metal oxides such. B. aluminum oxide or silicon oxide can be used. In addition, metals and / or metal oxide layers can be arranged one above the other in such a way that the individual layers are optionally constructed chemically equivalent or chemically non-equivalent. That is to say, one or more further barrier layers, such as an EVOH layer, can be arranged between the individual layers.

In a preferred embodiment, the carrier paper has a second coating on the second side opposite the first coating device, which does not completely cover this side of the carrier paper. As an alternative to the incomplete covering of the side opposite the first coating, a water-soluble coating could also be provided. This coating can be applied over the entire area. If a second coating is provided, it is therefore preferred that this provides a sufficient number of and sufficiently large sections that are not sealed by this coating and thus the solvent is provided before the contact with the solvent Can wet backing paper at least in these sections. At the latest when it comes into contact with the solvent, the second coating should expose sections that allow the carrier paper to be wetted by the solvent. This could be ensured by dissolving or peeling off the second coating.

However, some sections on the second side of the carrier paper are preferably not covered by the second coating. The second coating preferably covers a maximum of 50%, preferably less than 50%, more preferably up to 40%, particularly preferably up to 30% of one side of the carrier paper.

At least one coating can contain channels that are completely water-permeable. These channels are preferably produced selectively by means of laser perforation, for example as described in patent application EP3495138A1. During recycling of the paper-based packaging material, this enables the solvent (for example water) to penetrate the carrier paper from the second side. In particular, cellulose fibers from the carrier paper are transferred into the pulp. The process is known from the prior art.

The second coating is preferably a sealable coating. This enables this layer to be easily connected to a further layer or a section of packaging material. In particular, it is preferred that the second coating is a glue or adhesive.

In the case of a water-insoluble adhesive, channels can preferably be contained which facilitate the passage of water through the adhesive layer.

It is preferred, but not absolutely necessary, for the second coating to be water-soluble and / or water-degradable. This property, in conjunction with the above-mentioned arrangement of the second coating on the side of the carrier paper opposite the first coating, enables the water to wet the carrier paper directly even in the areas that are provided with the second coating and (if necessary in connection with mechanically introduced energy) can suspend cellulose fibers from the carrier paper as soon as the second coating arranged there through Water was at least partially dissolved or degraded. This means that these fibers are available again for a recycling process.

In a particularly preferred embodiment, the first and / or second coating comprises a hydrolyzable coating which is preferably applied over the entire surface and which is applied directly to at least one side of the carrier paper on the paper surface. As a result of the hydrolysis of the coating, the coating becomes detached from the paper, preferably together with additional layers applied to the coating (e.g. print, overprint varnish). The hydrolysis can already be triggered by transverse diffusion of water laterally over the cut edges of the carrier paper. The connection to the surface of the cellulose fibers that is created by thermal esterification with the functional polymer can be reversibly hydrolyzed again in an alkaline environment in the recycling process, thus detaching the primer from the paper surface.

Depending on the roughness and the porosity of the carrier paper, it can be advantageous to apply a primer to at least one side of the paper. A primer is thus net angeord in a preferred embodiment at least on one side of the carrier paper. The primer can preferably be printed with conventional printing inks (for example as a surface coating). The primer preferably comprises a polymer. This is preferably a polyethylene-dicarboxylic acid copolymer with preferably less than 60 percent by weight of dicarboxylic acid. The mean molar mass of the polymer is preferably> 60,000 g / mol, preferably> 70,000 g / mol, more preferably> 80,000 g / mol. In addition or independently thereof, the softening or glass transition temperature is preferably in the range from 120-200.degree. C., preferably 130-190.degree. C., particularly preferably 140-180.degree. Such polymers have been shown to be particularly suitable with regard to their adhesion properties and printability.

It is possible and, in one variant, particularly preferred for the polymer of the primer to comprise silicone-containing particles as described above, preferably polymethylsilsesquioxane. These are particularly suitable for filling cavities in the paper. This leads - in particular due to the small particle size - to a particular compactness and / or flatness of the surface of the carrier paper, so that it is optically particularly appealing and appears valuable. In addition, the application and / or the liability is another Layer, for example, the surface coating favors. In an advantageous embodiment, the Si-containing particles have a thermal stability that is> 300.degree. In order to be able to optimally control the barrier properties, the printability and the paintability, an additional crosslinking with a bi-functional aliphatic glycidyl ether is provided in a preferred embodiment.

The polarity of the paper coating is preferably set to a defined value. This is preferably done by adding a sufficient amount, preferably 5%, of glycidyl ether.

Because the cellulose fibers can be brought into suspension from the carrier paper by introducing a solvent from the first and / or second coating side, it is possible to degrade the carrier paper to such an extent that its structure collapses. As soon as this occurs at the latest, the stability of the first coating is preferably also reduced to such an extent that its structure also collapses. Independently of this, after resuspension of the cellulose fibers from the carrier paper (for example in a pulp), the separation of the first coating is made possible. In the case of larger coherent pieces of the first coating, this could be done, for example, by sieving.However, it is preferred that residues of the first coating together with other impurities in the cellulose fibers (e.g. ink, printer's ink or pigments) are removed from the pulp by flotation or separated from the cellulose fibers can be.

Such a paper-based packaging material offers, in addition to the improved recyclability, in particular advantages in terms of good processability. In addition, the barrier effect against mineral oil, water vapor and gas diffusion is retained after formation and gelation of gusseted bags, sachets, stand-up pouches, wrappers, flow packs, folding boxes and secondary packaging. The packaging of these packaging materials takes place on packaging machines which are known from the prior art. Furthermore, by selecting the backing paper, the chemical composition of the coatings and / or the layer thicknesses or by varying them, a sufficiently high puncture resistance, flexural rigidity, tensile rigidity, bursting pressure resistance, tensile strength, elongation at break, kink resistance, tear resistance and / or the springback force (for example compared to cardboard). The second coating is preferably a glue, an adhesive or a sealing layer. In addition to the possibility of using this layer directly for the production of closed packaging, this offers advantages with regard to the environmental compatibility of such a paper-based packaging material. This also offers advantages in terms of processing, since an adhesive layer could be stuck directly onto other areas of the packaging, for example in order to form a bag. It would also be conceivable to connect such a paper-based packaging material to a plastic container via the second coating in order to cover an opening in the plastic container (for example a yogurt cup) and thus to close it.

Materials that have proven to be particularly suitable as the second coating are selected from a group consisting of PVDC, PVOH, modified PVOH, acrylate, biopolymers, casein, starch, thermoplastic starch, sugar, cellulose, carboxymethyl cellulose, cellulose ether, xanthan, carrageenan , Polypeptides, proteins, gelatine, pectin, guar, chitin derivatives, chitosan derivatives (especially N-carboxymethylchitosan), dextran, gluten, hyaluronic acid, polyhydroxyalkanoate-based water-soluble polymer, ionomers, polyurethane, polyacrylic acid, hydrophilic polyacrylate, polyacrylamide (especially N- (2nd -Hydroxypropyl) -methacrylamide), polymethacrylic acid, copolymers of acrylic acid and / or methacrylic acid and their esters, polysulfonic acid, polyamine, amino resin, polyimine, polybetaine, polyethylene oxide, polyethylene glycol, homo-polyvinylpyrrolidone (especially poly-N-vinylpyrrolidone), vinyl pyrrolidone (especially vinyl pyrrolidone / vinyl laurate copolymers, vinyl pyrrolidone / vinyl imidazole and V inyl-pyrrolidone / vinyl-caprolactam), polyvinyl alcohol, polyvinyl alcohol / ethylene-vinyl alcohol copolymers, butenediol-vinyl alcohol copolymers (BVOH), acetalized polyvinyl alcohol, polyvinyl acetal, polyester, polyethylene imine, quaternary ammonium compounds, polyoxazoline, polyphosphate, carboxypolymethylene Polyvinyl methyl ether, maleic anhydride and polyacrylamide each individually, as a mixture and / or as copolymers. Even if this is not absolutely necessary for the paper-based packaging material to be sufficiently recyclable, these materials are preferred because they - at least in some designs and / or combinations - are water-soluble and / or can be split or degraded by water (within the scope of this invention also referred to as "water-degradable"). This is advantageous in terms of particularly good environmental compatibility and resource conservation. Biopolymers, particularly preferably casein, starch, especially preferably thermoplastic starch, cellulose, gelatin, proteins, especially Their preferred soy proteins and / or gluten are preferred with a view to conserving resources as much as possible in the product, its manufacture and its recycling. In addition, these materials are freely available and can be easily integrated into a paper-based packaging material.

The paper-based packaging material preferably has a thickness in the range of 30-300 μm, preferably 40-200 μm, particularly preferably 50-100 μm. These strengths have been shown to be advantageous because, on the one hand, they enable a sufficiently strong carrier paper and its coating (with at least a first coating and surface coating) and, on the other hand, are thin enough to be handled with processing machines commonly used in the packaging industry. The weight of paper-based packaging material in the above-mentioned strength range is low, so that when a product packaged with such a paper laminate is transported, there are no disproportionately high transport costs and the material yield is high.

The surface coating is preferably a printing ink. In a further preferred embodiment, this could be a color composition which comprises nitrocellulose, PVB, PVC, PA and / or PUR. Such color compositions have proven to be particularly suitable for being able to be applied in the gravure printing process. Regardless of the ink composition used, the gravure printing process is preferred for applying an ink composition, since it results in a particularly homogeneous print image and can be implemented particularly quickly, efficiently and inexpensively in terms of the process. In the case of a partial cold seal application on the surface of the first coating or directly on the surface of the carrier paper, an adhesive varnish can also be applied to the surface of the second coating and / or over the printing ink. As an alternative or in addition to gravure printing, however, other printing techniques for applying (colored) layers can also be used within the scope of the invention. Flexographic printing, offset printing, UV flexographic printing, EB flexographic printing (wetflex), sheet-fed offset printing, UV / EB offset printing and / or digital printing are, for example, conceivable and preferred for some applications and processes. For these printing processes, printing inks other than those mentioned above as preferred may be advantageous.

A paper-based packaging material is preferred in which the carrier paper has a thickness in the range from 25 μm to 290 μm, preferably 45 μm to 250 μm and especially preferably 50 gm - 200 gm. Depending on the other properties of the carrier paper (for example tear strength, weight per unit area, opacity, feel, type of filler and / or filler content), such a carrier paper has sufficient tear strength for use in the packaging industry, but on the other hand is sufficiently thin and light to allow use as packaging neither to add a lot of volume nor to increase the (transport) weight disproportionately.

The carrier paper preferably comprises or is a base paper with a density> 1 g / cm ³ . This preferably comprises a primary fiber material obtained from leaves and / or conifers and / or a secondary fiber material obtained from recycling material. As a result, and by means of measures known from the prior art, sufficient strength of the carrier paper can be guaranteed with a low weight. The methods required here are known to the person skilled in the art.

The carrier paper is preferably selected from a group consisting of biodegradable fiber materials, kraft paper, grass paper, cocoa fiber paper, straw paper, hemp paper, wood-free paper, tissue paper, colored paper, thick printing paper, gravure paper, document paper, duplicating paper, recycled paper, sandwich paper, parchment paper, parchment, thawing , Vellum paper and tracing paper. It has been shown that these papers are particularly suitable for enabling a stable connection to adjacent layers, in particular to the first coating, in a paper-based packaging material. The cellulose fibers of these papers can still be resuspended particularly easily in the recycling process.

Optionally, and preferred for some applications, the carrier paper and / or at least one further paper layer has a line. It is therefore a coated paper. As a coating color, chalk, kaolin, or casein-containing coating colors are given before given. The application of the line is known to the person skilled in the art from the prior art.

The paper-based packaging material preferably has a passage speed for water at 50 ° C of at least 90 g / m ² _* day, preferably> 100 g / m ² _* day, more preferably> 110 g / m ² _* day, particularly preferably> 120 g / m ² _* day. It has been shown that at this speed of passage there is sufficient protection provided by such packaging. Products enclosed in packaging material can be guaranteed, but there is sufficient resuspension in the pulp. In particular, it is preferred that the values given above for the passage speed are essentially or solely achieved by the combination of surface coating, first coating and carrier paper. If necessary, however, further layers can be provided in order to adjust the passage speed for water according to the respective requirements. If necessary, a second coating can be provided and / or a membrane and / or barrier layer regulating the passage speed.

A further solution to the problem presented above is a packaging which comprises a paper-based packaging material as described above. By using such a paper-based packaging material, it can be ensured with low weight and good visual perceptibility of the surface coating that, despite the barrier effect of the first coating, the cellulose fibers of the carrier paper are easily recyclable. In addition, despite the one-sided good accessibility of the carrier paper for potentially damaging substances, it can be ensured for the surface coating that it is not damaged by these substances for a long time and thus the paper-based packaging material remains visually appealing.

The surface coating can be designed in almost any way. In particular, it can visually display important information for the customer, for example about the product contained in the packaging. In order to keep this information accessible to a customer even without having to open the packaging, it is preferred that this surface coating is arranged on the outside of the carrier paper of the packaging. In particular, it is preferred that the surface coating is visible on the outside of the packaging. It could thus be arranged on the outside of the packaging. The surface coating can have a positive effect on the appearance and / or the feel of the packaging. The surface coating does not necessarily have to be the outermost layer of the packaging, but could optionally be overlaid by one or more (preferably transparent) layers (at least in sections).

The two coatings can be applied to any side of the carrier paper in various combinations. The second coating is preferably arranged on an inside of the packaging. As a result, if it is an adhesive layer, it can be used to connect sections of the paper-based packaging material with other sections of the paper-based packaging material or the packaging.

A packaging as described above is preferably a packaging selected from a group consisting of stick packs, bags, twist packaging, stand-up bags (doypack), stable bags, pillow bags, gusseted bags, resealable bags (flow wraps), tear-open bags Packaging, three-sided sealed packaging (3 ss), four-sided sealed packaging (4 ss), cubes, lids, transparent packaging, blisters, and packaging for pharmaceutical products.

Another aspect that is essential to the invention relates to a method for producing a paper laminate, which is preferably characterized by the following steps:

Providing a backing paper,

Providing a first coating material which is suitable for producing a barrier layer which has an increased diffusion resistance at least for one substance, which is preferably selected from a group comprising fluid, gas, air, oxygen, carbon dioxide, nitrogen, inert gas, odorous substance, Flavor, water vapor, liquid, water, water-fat emulsion, fat, oil, mineral oil, and edible oil, individually or in combination,

Applying the first coating comprising the first coating compound to one side of the carrier paper,

Providing a surface coating compound,

Applying the surface coating compound directly to the first Beschich device.

This process makes it particularly easy to produce a recyclable paper-based packaging material, in which the carrier paper is accessible on at least one side for substances that promote the detachment of cellulose fibers during recycling, but the surface coating by the first coating mass before is protected from this side by substances diffusing from the carrier paper. A variant of the method is preferred in which the carrier paper is provided with a second coating compound that does not completely cover this second side of the carrier paper before and / or after the application of the first coating to a first side on the second side opposite the first side.

The coatings can be applied independently of one another by suitable methods. Printing a coating has proven to be particularly suitable. Here, coating weights have from 0.5 to 100 g / m ^2, preferably 0.8 to 70 g / m ^2, particular DERS preferably 1-50 g / m ^2, most preferably 3-30 g / m ² proven advantageous . As an alternative or in addition to printing a layer, a layer could also be applied by extrusion, smooth roller application, screen cylinder application, casting application. Another preferred variant consists in applying the layer as a melt (“hot melt”). The last two variants mentioned have proven to be particularly advantageous when higher application weights are desired. Printing the coating by extrusion or as a melt has proven to be particularly suitable when application weights of 1-100 g / m ² , preferably 2-70 g / m ² , particularly preferably 3-50 g / m ^2, very particularly preferably 3 - 30 g / m ^{2 are} desired.

In the case of the application of metals and / or metal oxides, vapor deposition in a high vacuum is a preferred method. Preferably with a layer thickness of 0.01-0.1 μm.

In a preferred variant of the method, the method additionally comprises the step of joining at least one section of the second coating to form a package with the formation of an adhesive connection with other sections of the same paper laminate or another packaging material. If the second coating is an adhesive or glue, this can be done without additional adhesive materials. As an alternative to this, it would also be advantageous to introduce an adhesive or a glue to form an at least temporarily stable adhesive connection between the above-mentioned sections. As an alternative to this, in some cases it is also advantageous that the second coating can be activated thermally and / or chemically and, in this activated form, is suitable for forming the desired, at least temporarily stable, adhesive connection between the above-mentioned sections. The first coating is preferably applied directly to the carrier paper. Alternatively, one or more intermediate layers can also be provided. A layer is preferably applied by a method selected from a group comprising dry lamination, wet lamination, thermal lamination, extrusion lamination, water-based adhesive lamination, solvent-based adhesive lamination and solvent-free adhesive lamination. However, wet lamination is particularly preferred, in particular water-based adhesive lamination, since the use of organic solvents such as ethyl acetate can be avoided. This is particularly advantageous with regard to production costs, occupational safety and disposal. At the same time, with a water-based adhesive lamination, it is possible to adjust the properties of the paper-based packaging material so that it can be easily processed with conventional machines.

If a cold seal lacquer is provided as the second layer (in sections) on the second side of the paper-based packaging material (for example to glue this side to other sections to form a packaging), the opposite side of the paper-based packaging material (for example the surface coating) is preferred. to be provided with a separating lacquer. The release varnish should be arranged at least where this side could come into contact with the cold seal varnish during manufacture or further processing. This makes it possible to avoid the undesired sticking of these sections of the paper-based packaging material to one another (for example when making up as rolls).

The release varnish is preferably a release varnish based on a nitrocellulose / polyamide resin combination. In a paper-based packaging material, this has proven to be particularly advantageous in terms of adhesive strength and behavior in the recycling process.

A second coating in the form of a lacquer, glue, film or (co) extrusion coating preferably has a thickness of preferably 1 - 100 g / m ² , preferably 2 - 70 g / m ² , particularly preferably 5 - 50 g / m ² very particularly preferably 3 to 30 g / m ² . Such a coating is preferably applied to the carrier paper prior to its further processing as part of the production of the paper-based packaging material. Processes that are preferred for this are selected from a group consisting of laminating, lacquering, Flexographic printing, screen printing, gravure printing and particularly preferably painting by means of a wide slot nozzle (“curtain coating”), or smooth roller or anilox roller application. These processes enable particularly thin second coatings, which means that this can be done in a way that is particularly gentle on materials and resources.

By selecting a carrier paper and / or the coatings, it is possible to set both the mechanical and the barrier properties of the paper-based packaging material. The mechanical properties of the paper-based packaging material can be adapted by combining different types of paper and / or coatings to the respective needs in the context of use as packaging (for example with regard to the format or the workability).

In order to improve the barrier properties of the paper-based packaging material, for example against fat, it is preferred to select the carrier paper and / or a further paper layer independently of one another from a group of papers that have a high KIT value (i.e. a high level of fat penetration resistance). and have a low porosity.

Exemplary paper-based packaging materials are described below. However, these compositions are only examples, without restricting the invention to these embodiments.

Example 1: Heat-sealable paper-based packaging material

Layer sequence: a) surface coating, b) barrier layer, weight per unit area> 1 g / m ² , comprising three-dimensionally cross-linked silicone-containing powder (particle size <1 μm), c) kraft paper, weight per unit area> 40 g / m ² , d) partially applied heat seal lacquer, weight per unit area ( in the coated sections)> 3 g / m ² ,

The only partially applied heat seal lacquer of layer d) enables water to wet the Kraft paper (layer c)) in the uncoated areas and during recycling cellulose fibers can be extracted from it. When used as packaging, the extremely flexible surface coating cannot be damaged or destroyed by liquid (for example water, oil or fat) diffusing through the kraft paper (layer c)) due to the barrier layer b). Instead of the heat-sealing lacquer, a work-sealing coating with a thickness of more than 5 μm could also be used. If the cold sealability of the sealing layer is desired, the industrial sealing lacquer applied in sections could be replaced by a cold sealing lacquer applied in sections, for example with a thickness of more than 3 μm. Example 2: Hard-sealable paper-based packaging material with printing

Layer sequence: a) Optional topcoat, weight per unit area> 1 g / m ² , b) Printing ink, c) Barrier ^{layer, weight per unit area> 1 g / m 2} , comprising three-dimensionally cross-linked silicone-containing powder (particle size <1 μm), d) Kraft paper, weight per unit area> 40 g / m ² , e) Partly applied industrial seal lacquer, weight per unit area (in the coated sections)> 3 g / m ² .

The optional topcoat according to a) can also serve to adapt the properties of the surface with regard to its mattness, gloss, feel or improved friction to special requirements. Here, too, the only partially applied industrial seal lacquer enables solvent to access the carrier paper (layer d)) during recycling.

Example 3: Extrusion-coated paper-based packaging material with printing

Layer sequence: a) Printing ink (partial) b) Hydrolyzable varnish <3 g / m ² c) Kraft paper weight per unit area> 50 g / m ² , coated on one side, paper coating inwards d) Extrusion primer (e.g. PBS)> 3 g / m ² e) PVOH> 5 g / m ² f) Extrusion top layer (e.g. PBS)> 3 g / m ² g) heat-sealing lacquer,> 5 g / m ² optionally with barrier properties against water vapor (e.g. ionomer-based lacquer) Example 4: Heat-sealable, double-sided hydrolysable, paper-based packaging material with printing

Layer sequence: a) printing ink (partial) b) hydrolysable varnish <3 g / m ² c) kraft paper weight per unit area> 40 g / m ² , coated on one side, paper coating inwards d) hydrolysable varnish <3 g / m ² e) heat seal varnish,> 5 g / m ² optionally with barrier properties against water vapor (e.g. ionomer-based paint)

Example 5: Heat-sealable on both sides hydrolyzable metallized paper-based packaging material with print layer sequence: a) aluminum metallization b) hydrolyzable paint <3 g / m ² c) kraft paper basis weight of> 40 g / m ^2, coated on one side, the paper coating according to NEN d) hydrolyzable Lacquer <3 g / m ² e) Heat seal lacquer,> 5 g / m ² optionally with barrier properties against water vapor (e.g. ionomer-based lacquer)

Example 6: Heat-sealable, paper-based packaging laminate

Layer sequence: a) Kraft paper weight per unit area> 40 g / m ² b) Glue or glue (possibly laser-perforated) c) Aluminum metallization d) Hydrolyzable varnish <3 g / m ² e) Kraft paper weight per unit area> 40 g / m ² , coated on one side, paper coating towards the inside f) Hydrolyzable varnish <3 g / m ² g) Heat seal varnish,> 5 g / m ² optionally with Barrier properties against water vapor

(e.g. ionomer-based paint)

Example 7: Heat-sealable, channel-perforated, paper-based packaging material with a surface coating

Layer sequence: a) Full surface coating <2 g / m ² with perforated channels b) Printing ink (partial) c) Water-soluble primer <2 g / m ² (e.g. cellulose derivative) with perforated channels d) Kraft paper weight per unit area> 40 g / m ² , coated on one side, paper coating facing inwards e) Full-surface barrier varnish (e.g. styrene acrylate base)> 5 g / m ² f) Partial cold-sealing varnish Example 8: Heat-sealable, paper-based packaging material perforated with channels with a surface coating

Layer sequence: a) Paraffin wax-based hotmelt (partial) b) Printing ink (partial) c) Water-soluble primer <2 g / m ² (e.g. cellulose derivative) with perforated channels d) Kraft paper weight per unit area> 40 g / m ² , coated on one side, Paper coating towards the inside e) Full-surface barrier varnish (e.g. styrene acrylate base)> 5 g / m ² f) Hotmelt based on paraffin wax (partial) The applicant reserves the right to claim all features disclosed in the application documents as essential to the invention, provided that they are new to the state of the art, individually or in combination. It is further pointed out that features have also been described in the individual figures, which can be advantageous per se. The person skilled in the art immediately recognizes that a certain feature described in a figure can also be advantageous without the adoption of further features from this figure. Furthermore, the person skilled in the art recognizes that advantages can also result from a combination of several features shown in individual or in different figures.

Claims

Paper packaging material with improved resuspendability of the cellulose fibers

1. Paper-based, recyclable packaging material, in particular paper packaging material for food containers, with a carrier paper and a first coating arranged indirectly on the carrier paper at least on one side, the first coating at least for one substance selected from a group comprising fluid, gas, air, oxygen , Carbon dioxide, nitrogen, inert gas, odorous substance, aromatic substance, water vapor, liquid, water, water-fat emulsion, fat, oil, mineral oil (MOSH (Mineral Oil Saturated Hydrocarbons or saturated mineral oil hydrocarbons) MOAH (Mineral Oil Aromatic Hydrocarbons), POSH ( Polyolefinic saturated hydrocarbons) or aromatic mineral oil hydrocarbons)) and edible oil individually or in combination, has an increased diffusion resistance compared to paper, characterized in that the first coating between the carrier paper and an optically perceptible surface layer ung is arranged and the surface coating contacted directly.

2. Paper-based packaging material according to claim 1, characterized in that the first coating is a barrier layer and this is preferably selected from a group consisting of PVDC, PVOH, modified PVOH, acrylate, biopolymers, Ca, starch, thermoplastic starch, sugar, cellulose , Carboxymethyl cellulose, cellulose ethers, xanthan, carrageenan, polypeptides, proteins, gelatin, pectin, guaran, chitin derivatives, chitosan derivatives (especially N-carboxymethylchitosan), dextran, gluten, hyaluronic acid, polyhydroxyalkanoate-based water-soluble polymer, ionacrylic acid, hydrophilic polyacrylate, polyurethane, polyacrylic acid Polyacrylamide (especially N- (2-hydroxypropyl) methacrylamide), polymethacrylic acid, copolymers of acrylic acid and / or methacrylic acid and their esters, polysulfonic acid, polyamine, amino resin, polyimine, polybetaine, polyethylene oxide, polyethylene glycol, homo-polyvinylpyrrolidone (especially poly-N-vinylpyrrolidone), vinyl-pyrrolidone (especially vinyl pyrrolidone / vinyl laurate copolymers, vinyl pyrrolidone / vinyl imidazole and vinyl pyrrolidone / vinyl caprolactam), polyvinyl alcohol, polyvinyl alcohol / ethylene-vinyl alcohol copolymers, butenediol-vinyl alcohol copolymers (BVOH), acetalized polyvinyl alcohol , Polyvinyl acetal, polyester, polyethyleneimine, quaternary ammonium compounds, polyoxazoline, polyphosphate, carboxypolymethylene, polyvinyl methyl ether, maleic anhydride and polyacrylamide each individually, as a mixture and / or as copolymers.

3. Paper-based packaging material according to claim 2, characterized in that the carrier paper has a second coating on the second side opposite the first coating, which preferably does not completely cover this side of the carrier paper, the second coating preferably being a sealable coating.

4. Paper-based packaging material according to one of claims 2-3, characterized in that the optically perceptible surface coating on the side opposite the barrier layer is covered at least in sections, preferably over the entire surface, by a protective layer, preferably a lacquer.

5. Paper-based packaging material according to one of claims 2-4, characterized in that the second coating covers a maximum of 50%, preferably less than 50%, more preferably up to 40%, particularly preferably up to 30% of one side of the carrier paper.

6. Paper-based packaging material according to one of the preceding claims, characterized in that the paper-based packaging material has a passage speed for water at 50 ° C of at least 90 g / m ² _* day, preferably> 100 g / m ² _* day, more preferably> 110 g / m ² _* day, particularly preferably> 120 g / m ² _* day.

7. Packaging, in particular for food or dry filling goods, preferably dry food, characterized in that it comprises a paper-based packaging material according to one of the preceding claims.

8. Packaging according to claim 7, characterized in that the second coating is arranged on an inside of the packaging.

9. A method for producing a paper-based packaging material, characterized by the steps:

Providing a backing paper,

Providing a first coating material which is suitable for producing a barrier layer which has an increased diffusion resistance for at least one substance, which is preferably selected from a group comprising fluid, gas, air, oxygen, carbon dioxide, nitrogen, inert gas, odorous substance, Flavor, water vapor, liquid, water, water-fat emulsion, fat, oil, mineral oil, and edible oil, individually or in combination,

Providing a surface coating compound,

Applying the surface coating composition directly to the first coating.

10. A method for producing a paper-based packaging material according to Pa tentans claims 9, characterized in that the carrier paper before and / or after the application of the first coating to a first side on the second side opposite the first side with a second side of the carrier paper not over the entire surface covering second Be coating compound is provided.