WO2013066246A1

WO2013066246A1 - Migration barrier film or coating comprising hemicellulose

Info

Publication number: WO2013066246A1
Application number: PCT/SE2012/051141
Authority: WO
Inventors: Maria GRÖNDAHL; Lisa BINDGÅRD; Magnus Palmlöf
Original assignee: Xylophane Aktiebolag
Priority date: 2011-10-31
Filing date: 2012-10-24
Publication date: 2013-05-10
Also published as: ES1129505U; DE212012000194U1; ES1129505Y

Abstract

The present invention relates to afilm or coating for preventing migration of substances from paper or board containing recycled fibers, wherein said film or coating is a polymeric film or coating comprising hemicellulose, wherein said film or coating is arranged to form a migration barrier layer with a thickness equal to or less than 50 µm, preferably less than 20 µm, preferably less than 15µm, preferably between 2 -15 µm, even more preferred between 5 –10 µm.

Description

MIGRATION BARRIER FILM OR COATING COMPRISING HEMICELLULOSE

DESCRIPTION TECHNICAL FIELD

The present invention relates to a film-forming composition and a polymeric film or coating comprising hemicellulose. It also relates to the use of said film or coating as a migration barrier for paper or board containing recycled fibers. BACKGROUND OF THE INVENTION

As disclosed in WO 2004/083286, the majority of plastic materials for packaging are today based on petroleum. However the fossil resources on the earth are limited.

Incineration results in an increase of the greenhouse effect and furthermore these materials are in general not degradable. A sustainable development in the future requires a conversion to the use of renewable raw materials.

The use of recycled fibers is a way to improve sustainability of packaging. However, recently there has been an extensive concern about using recycled fibers in materials for food packaging. Toxic substances that are left in the recycled fibers have been found to migrate into the food stuffs. Examples of substances are ingredients of printing inks or adhesives. Particularly, substances of health-concern, such as primary aromatic amines, 4,4'-Bis(dimethylamino)-benzophenone, phthalates, such as diethylhexyl phthalate, din-butyl phthalate and diisobutyl phthalate, benzophenone, bisphenol A and

diisopropylnaphtalene have to be taken into account (BfR recommendation XXXVI. Paper and board for food contact as of 01.03.2011). One way to overcome this problem is to convert to the usage of virgin fibers instead of recycled fibers. However, the availability of virgin fibers is limited and a more sustainable alternative would be to modify the packaging materials produced from recycled board in a way that prevents migration from the fibers to the packed goods. A way to achieve this is to apply a functional barrier layer onto the paper or board to be used for packaging of food stuffs and other consumer goods. It is preferable that the barrier material is based on renewable resources. Furthermore, it is desirable that the material is flexible, mechanically resistant, transparent and of low cost. Examples of materials that can be used to achieve functional migration barriers are aluminum, EVOH and metallized plastic films. However, these alternatives are associated with disadvantages. For example, the use of plastic materials together with a paper product may pose a problem during the recycling procedure, as is also the case for metal based barrier materials. Thus, there is a need for new biodegradable, recyclable and/or renewable film-forming compositions, which overcome the abovementioned problem, and present the desired property of preventing migration of sub stance/sub stances from paper or board containing recycled fibers to the packed food stuffs or other consumer goods.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide renewable and biodegradable films or coatings for packaging reducing the migration from recycled paper and board to the packed food stuffs or other consumer goods.

It has surprisingly been found that a film-forming composition of hemicellulose, for example of xylans, is capable of providing a very efficient barrier against migration of substances from recycled paper or board. Thus, the aforementioned objects are achieved by mixing hemicellulose with a solvent such as water and applying a coating layer onto recycled paper or board.

Another advantage relates to that the functional barrier, in the form of a hemicellulose- based barrier, may be applied by dispersion coating onto the paper or board which is beneficial since paper and board producers often have dispersion coating capacity and thus the barrier layer can be applied in an efficient way. Also, the water solubility of hemicellulose is an advantage in industrial coating processes since a solvent does not have to be used in the dispersion procedure.

Hemicelluloses are polysaccharides that are biosynthesized in the majority of plants, where they act as a matrix material present between the cellulose micro fibrils and as a linkage between lignin and cellulose. Hemicelluloses have been commercially used as sweetening agents, thickeners and emulsifiers in food, however so far the non-food utilization of hemicelluloses has been very limited. For example, not until WO

2004/083286 have they been suggested to be used commercially for the preparation of polymeric materials for packaging.

Hemicelluloses can be isolated from agricultural residues such as husks and hulls or from by-products from pulping industry. Thus, the isolation of hemicelluloses and the use of these materials in commercial applications enable a more efficient use of resources. High-value products are produced from low- value by-products. Also, unlike starch-based products, there is no competition with food applications. It is previously known to use hemicelluloses as a base in barrier layers. WO

2008/103123 describes a polymeric film or coating comprising hemicelluloses, which has been used for creating a liquid/moisture resistant layer on paper or paperboard and plastics. To our knowledge, however, it has never before been suggested that hemicelluloses would be capable of providing a migration barrier preventing overall migration of the various substances present in recycled fibers. Nevertheless it has been shown that hemicelluloses may be used to form a very efficient barrier against substances such as (but not limited to): primary aromatic amines, 4, 4'- bis(dimethylamino)-benzophenone, phthalates, such as diethylhexyl phthalate, di-n- butyl phthalate and diisobutyl phthalate (DIBP), benzophenone, bisphenol A, diisopropylnaphtalene (DIPN), aliphatic hydrocarbons, 2,2,4-trimethyl-l,3-pentanediol di-isobutyrate (TXIB), isopropyllaurat (IPL), diisopropylnaphtalene (DIPN) and fatty acid esters. It is understood that the term "preventing" used herein is to be interpreted as substantially reducing the overall migration from the recycled paper or board, for instance reducing migration by at least 80%. However, in some cases where the detection limit of the measuring method is relatively high, e.g. 0.1 mg/dm², the measuring of reduction of the migration from a relatively low level (e.g. 0.2) may not enable to conclude if the reduction was at least 80% or not. In such cases the migration is also considered to have been prevented, since from a functional view it implies that a sufficiently good migration barrier exists to enable a low totally migrated amount.

According to one aspect of the invention the aforementioned object/s is/are achieved by means of a film or coating for preventing migration of substances from paper or board containing recycled fibers, wherein said film or coating is a polymeric film or coating comprising hemicellulose.

According to one aspect of the invention, the film or coating has a hemicellulose content in % by dry weight of 10-100 %, preferably 20-70 %. Depending on desired needs/properties of the film/coating the amount may vary substantially, especially depending on amounts of other substances in the film/coating and the main purpose of the coating/film, e.g. if a relatively low flexibility of the film/coating may be accepted, it may be beneficial that the hemicellulose content is in the lower range (e.g. 10-40%), combined with a relatively high amount of filler and possibly also plasticizer. The other way around if a relatively high flexibility of the film/coating is desired a higher hemicellulose content (e.g. 40-70%) may be desired. As understood by the skilled person, fillers may in some cases be used in the film/coating to occupy volume, for instance in order to thereby reduce the cost by means of reducing the content of the more expensive hemicelluloses. Fillers are preferably inert compounds/sub stances, i.e. non-reactive, and may affect the mechanical properties of the coating, such as the stiffness. One advantage when using a filler is that the dry content of the aqueous slurry can be increased with minor increase of the viscosity of the slurry. Thus, it is possible to either apply a thicker coating with remaining amount of water to dry off or to apply the same amount of material with a lower amount of water to dry off. Drying capacity is often a limiting factor when applying aqueous dispersions since the drying time is limited in industrial coating equipment. Also, drying is an energy demanding process.

According to one aspect of the invention the filler is selected from the group consisting of silica, talc, clay, calcium carbonate, mica, kaolin, wollastonite, montmorillonite, feldspar, barytes, glass fibers and carbon fibers.

According to another aspect of the invention the filler is contained in an amount of from 0 to 60 wt.%, based on the total weight of the coating composition, e.g. 30-60%, 30- 50% or 40-50%.

According to yet another aspect of the invention, said barrier layer has a thickness equal to or less than 50 μπι, preferably between 1-25 μπι, more preferably between 1-20 μπι, even more preferably between 1-15 μπι, even more preferably between 2-15 μπι, even more preferably between 2-10 μπι and most preferably between 2-5 μπι or 5 - 10 μπι.

A further advantage is that the raw material in the present invention is renewable and can be extracted from biomass. A migration barrier based on hemicellulose is further advantageous since such a barrier can be applied on a paper product (for containing food stuff) containing recycled fibers resulting in a container which is recyclable as a whole, with no need for any separating e.g. of the barrier material from the container prior to recycling or composting.

Materials based on biosynthesized polymers also have several environmental advantages. After their use, these materials do not give rise to a net increase of carbon dioxide in the atmosphere and in addition they are biodegradable and as such can be disposed of by composting. DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS OF THE

INVENTION

In the research work first leading to the invention disclosed in WO 2004/083286 and then to the present invention it was shown that coherent films based on hemicellulose, in particular pentosan-rich polysaccharides, e.g. xylans, exhibit excellent oxygen barrier properties. According to the latest surprising findings it has been seen that

hemicellulose also possesses the capacity of preventing migration of substances present in paper or board containing recycled fibers.

Hemicelluloses are substituted/branched polymers of low to high molecular weight. Examples of molecular weights of hemicelluloses are M_w=l 000-50 000 g/mol for glucuronoxylan (or 10 000-20 000 g/mol), M_w=l 000-500 000 g/mol for arabinoxylan (or 10 000-100 000 g/mol, or 20 000-50 000 g/mol), M_w= 1 000-50 000 g/mol for glucomannan from softwood (or 10 000-20 000 g/mol), and M_w=20 000-1 000 000 g/mol for konjac glucomannan. Hemicelluloses consist of different sugar units arranged in different portions and with different substituents. Pentosan-rich polysaccharides have a major pentose content and constitute the largest group of hemicelluloses. As used herein a "pentosan-rich polysaccharide" refers to a polysaccharide having a pentosan content of at least 20 % by weight, and a xylose content of at least 20 % by weight; for example, the polysaccharide has a pentosan content of 40 % to 80 % by weight, and a xylose content of 40 % to 75 % by weight. Pentosan-rich polysaccharides, in particular xylans, are the most preferred substances for use according to the present invention. However, other kinds of hemicelluloses may be used according to the invention, e.g. glucomannan, galactoglucomannan or arabinogalactan. Xylans are present in biomass, such as wood, cereals, grass and herbs, and they are considered to be the second most abundant biopolymer in the plant kingdom. To separate xylans from other substances in various sources of biomass, extraction with water or aqueous alkali can be used. Xylans are also commercially available from sources as Sigma Chemical Company.

Xylans may be divided into the sub-groups of heteroxylans and homoxylans. The chemical structure of homoxylans and heteroxylans differs. Homoxylans have a backbone of xylose residues and have some glucuronic acid or 4-O-methyl-glucuronic acid substituents. Heteroxylans also have a backbone of xylose residues, but are in contrast to homoxylans extensively substituted not only with glucuronic acid or 4-O-methyl-glucuronic acid substituents but also with arabinose residues. An advantage of homoxylans compared to heteroxylans is that homoxylans crystallize to a higher extent. Crystallinity both decreases gas permeability and moisture sensitivity. An advantage of heteroxylans compared to homoxylans is that heteroxylans have a better film-forming ability and more flexible films and coatings can be produced. An example of homoxylans which can be used according to the invention is

glucuronoxylan.

Examples of heteroxylans which can be used according to the invention are

arabinoxylan, glucuronoarabinoxylan and arabinoglucuronoxylan.

Xylans from any biomass or commercial source may be used to produce the films or coatings in the present invention.

A composition of hemicellulose with good film- forming properties, in particular xylans, may be achieved by various strategies. One way to do this is to add low molecular weight plasticizers. Another way to prepare coherent films is to add finely divided cellulose. A third procedure to obtain films is by blending xylan with other oligomers or polymers. An additional strategy to achieve better film-forming properties is to mix hemicelluloses of different molecular weights or structures. It is also possible to use a combination of one or more of the before mentioned strategies.

The films or coatings may be prepared by casting of an aqueous solution or dispersion of the pentosan-rich polysaccharide or by solution coating or dispersion coating of the pentosan-rich polysaccharide. Although other solvents could be used as solvents in the present invention, water is the most preferred solvent.

As used herein, the term "film" refers to a separate sheet or web having no carrier. The film can be combined with recycled paper or board by lamination technology. As used herein, the term "coating" refers to a covering applied on a carrier, e.g. a web of cellulosic fibers, a sheet, or a film to provide a barrier layer. The film or coating according to of the invention has a thickness equal to or less than 50 μπι, preferably between 1-25 μπι, more preferably between 1-20 μπι, even more preferably between 1-15 μπι, even more preferably between 2-15 μπι, even more preferably between 2-10 μιη and most preferably between 2-5 μιη or 5 - 10 μιη.

The expression "plasticizer" as used herein relates to a substance of low molecular weight, which increases the flexibility of the material. Examples of plasticizers that may be used are water, sugars such as glycerol, xylitol, sorbitol and maltitol, ethylene glycol, propylene glycol, butanediol, glycerine, citric acid and urea. Also combinations of different plasticizers together can be used.

Suitably, the content of plasticizer is in the range of 0 to 60 % by dry weight, e.g. in the range of 20 to 50 % or 30 to 50 % by dry weight. The expression "filler" as used herein relates to a substance, preferably an inert substance, that may be used in the film/coating to occupy volume for instance in order to thereby reduce the cost by decreasing the content of the more expensive

hemicellulose. Examples of fillers that may be used are silica, talc, clay, calcium carbonate, mica, kaolin, wollastonite, montmorillonite, feldspar, barytes, glass fibers and carbon fibers.

Suitably, the content of filler is in the range of 0 to 60 % by dry weight, e.g. in the range of 30 to 60%, 30 to 50% or 40 to 50% by dry weight. Cellulose can be added to improve the film-forming and/or barrier properties of the hemicellulose-based film or coating. The cellulose can originate from any biomass such as cotton, wood and agriculture residues or commercial source or be produced by bacteria. Preferably the cellulose is finely divided. For example, the finely divided cellulose can be in the form of nanofibrils or as whiskers. Suitably, the content of finely divided cellulose is in the range of 0 to 50 % by dry weight, e.g. in the range of 1 to 20 % by dry weight or 1 to 10 % by dry weight.

As long as the main substance of the film or coating is made from a biomass, a polymer or oligomer of any type can be added. Thus, while a synthetic polymer or oligomer may be used, one that is based on biomass is preferred. For example, the polymer or oligomer added is polyvinyl alcohol, starch or beta-glucan of various molecular weights. Suitably, the content of polymer or oligomer is in the range of 0 to 60 % by dry weight, e.g. in the range of 1 to 50 % by dry weight or 1 to 40 % by dry weight.

By the expression "migration barrier" used throughout this application is meant a material which prevents the migration of substances from a material as recycled paper or board to another material. The films or coatings of the present invention can be used to form migration barriers preventing migration of substances present in paper or board containing recycled fibers, where non-limiting examples of such toxic substances may be for instance primary aromatic amines, 4, 4'-bis(dimethylamino)-benzophenone, phthalates, such as diethylhexyl phthalate, di-n-butyl phthalate and diisobutyl phthalate (DIBP), benzophenone, bisphenol A, aliphatic hydrocarbons, 2,2,4-trimethyl-l,3- pentanediol di-isobutyrate (TXIB), isopropyllaurat (IPL), diisopropylnaphtalene (DIPN) and fatty acid esters.. The polymeric film or coating has a hemicellulose content in % by dry weight of 10- 100 %, preferably 20-70 %, e.g. 10-40% or 40-70%.

The coatings according to the present invention can be applied onto substrates based on paper, paperboard and plastics.

An advantage in using biodegradable and/or renewable substrates is that the multilayer packaging material can be easily recycled by composting. The use of biodegradable and/or renewable substrates is further advantageous from an environmental point of view. Examples of biodegradable and/or renewable substrates are board, paper and biodegradable and/or renewable plastics such as polylactic acid, polyhydroxy alkanoates, starch-based plastics including derivatives of starch, cellulose-based plastics including derivatives of cellulose, biodegradable polyesters, polyesters based on renewable raw materials, polyethylene based on renewable raw materials etc. We have found that one drawback with coating onto fiber-based substrates, such as paper and paperboard, is that the aqueous dispersion or solution penetrates into pores and liquid-absorbing fibers of the substrate. This brings on that a greater amount of solution or dispersion is needed to obtain a functional coating. Hemicellulose is interacting with cellulose/cellulosic fibers to a great extent, since they naturally occur together in plants and wood tissue. One way to overcome the abovementioned problem is to make a pre-coating onto the porous and liquid-absorbing substrate, which reduces the penetration of solution or dispersion. Further the use of pre-coating can prevent formation of cracks in the coating. Preferably the pre-coating reduces the porosity of the substrate. Examples of such materials are viscous polymer solutions or dispersions, such as cellulose derivatives, polyvinyl alcohol, starch, alginate and other polysaccharides. More preferably, the pre- coating also increases the hydrophobicity of the substrate. Examples of such materials are latexes, such as styrene butadiene latex and styrene acrylate latex, and thermoplastic resins. The pre-coating can also contain a mixture of the above mentioned substances and fillers.

Another way to reduce the porosity and/or liquid-absorbing nature of the substrate is by surface sizing or sizing of the substrate.

Further, the coatings according to the present invention may be applied onto the substrate in existing industrial dispersion coating or solution coating processes.

Dispersion coating or solution coating is a process commonly applied in paper and paperboard production. Coating onto paper and paperboard-based substrates may be advantageous since the process equipment for application is already available and no investment in new machinery or equipment is needed.

If desired, the coated substrates according to the present invention can be further protected with a moisture barrier such as thermoplastic resins or wax. Examples thereof are polyesters, such as polyethylene terephthalate (PET); polyamides such as nylon; polyolefins such as low-density polyethylene, high-density polyethylene, linear low- density polyethylene, ethylene-vinyl acetate copolymers, polypropylene, ethylene- acrylic acid copolymers, ethylene-acrylic acid salt copolymers and ethylene-ethyl acrylate copolymers; polyvinyl chloride; polyvinylidene chloride; and polyphenylene sulfide. Also biodegradable and/or renewable plastics such as polylactic acid, polyhydroxy alkanoates, starch-based plastics including derivatives of starch, cellulose- based plastics including derivatives of cellulose, biodegradable polyesters, and polyesters based on renewable raw materials, polyethylene based on renewable raw materials etc. can be used. Examples of waxes that can be used are natural and synthetic waxes. For multilayer structures according to the present invention where other biodegradable and/or renewable substances are used, a biodegradable and/or renewable moisture barrier is preferred. To improve the adhesion between the different layers, corona treatment can be used. The substrate may be corona treated prior to coating in a continuous process. If desired, conventional additives that are known in the art can be included in the film or coating of the present invention. For example, pigments, other colorants, stabilizers, adhesion promoters, preservatives, biocides, pH control agents, foam control agents, rheology modifiers, process aids and fillers can be included in the films and coatings of the present invention. Also cross-linkers and hydrophobizing agents, such as citric acid, boric acid, polyamidoamine-epichlorohydrin, ethylene acrylic acid copolymer, formaldehyde, glyoxal, melamine glyoxal, zirconium carbonates, such as ammonium zirconium carbonate and potassium zirconium carbonate, epichlorohydrin, phosphoric acid, acrolein, acid anhydrides, rosin, alkenyl succinic anhydride, and alkyl keten dimer can be included in the films and coatings.

It is understood that the objects of the present invention set forth above, among those made apparent by the detailed description, shall be interpreted as illustrative and not in a limiting sense. Within the scope of the appended claims the set-up of various alterations of the present invention may be possible, for instance that the migration barrier can be applied onto the paper or board in many ways while still achieving the migration barrier functionality. It is for instance possible to apply the coating onto a separate nonfunctional film (e.g. a plastic film) which is thereafter laminated onto the paper or board as well as it is possible to apply the coating directly onto the paper or board substrate, as previously described. The paper could be a liner or fluting that is further converted to corrugated board in primary or secondary packaging or a paper that is laminated in several layers to boxboard.

EXAMPLES In the following examples hemicellulose-based coatings are used. Hemicellulose may be in the form of xylan, in particular arabinoxylan, however it is to be understood that many other sources of hemicellulose are available.

Hemicelluloses can be isolated from different sources by methods described in literature. For example, the isolation of arabinoxylan from barley husks is described by Hoije et al (Carbohydrate Polymers, 61, 2005, p. 266-275). The isolation of

glucuronoxylan from aspen (hardwood) is described by e.g. Gustavsson et al (Biorelated Polymers - Sustainable Polymer Science and Technology, ed. Chiellini, Braunegg, Buchert, Gatenholm & van der Zee.New York: Kluwer Academic/Plenum Publishers, 2001, p. 41-52). The isolation of glucomannan from spruce (softwood) is described by e.g. Stalbrand et al (Hemicelluloses: Science and Technology, ed. Gatenholm &

Tenkanen, ACS Symposium Series 864, 2004, p. 66-78). Further methods on how to isolate hemicelluloses from biomass are described by e.g. Lindblad et al

(Polysaccharides - Structural diversity and functional versatility, ed. Dumitriu, New York: Marcel Dekker, 2005, p. 491-508) and Ebringerova et al (Macromolecular Rapid Communications, 21, 2000, p. 542-556).

In the examples, all amounts in % are weight per cent based on dry matter. The thickness of the films or coatings can be measured for example by using a micrometer.

Example 1

This example illustrates the production of a hemicellulose-based coating onto different recycled board qualities and the effect on the migration from the board grade to the food simulant. Board A: Classic-newsback from RockTenn Dallas Mill, TX, USA. This is a board grade based on 100% recycled fiber with 309.3 g/m² (69 lbs./1000 sq. ft.).

AngelCote Low Density CRB from RockTenn Battle Creek Mill, MI, USA. This is a board grade based on 100% recycled fiber with 291.3 g/i (65 lbs./1000 sq. ft).

Board C: Top Print GD3 from Smurfit Kappa Carton, a fully coated white lined chipboard, top side lightly wood containing white, filler grey, reverse side grey, 350 g/m².

Board D: Multiprint GD2 from Smurfit Kappa Carton, a fully coated white lined chipboard, top side lightly wood containing white, filler grey, reverse side grey, 350 g/m². Board E: Serviboard GD2 from RenoDeMedici, a fully white lined chipboard, grey back, with 300 g/m². Board F: Serviliner GD from RenoDeMedici, a fully coated white lined chipboard, grey back, with 250 g/m².

A pre-coating layer of styrene butadiene-latex was applied onto the different board grades using a wire wound bar with 24 μιη wet deposit resulting in about 12 μιη dry coating layer after drying at 105°C in an oven for 3 minutes. A xylan-based coating containing 70% arabinoxylan isolated from barley husks and 30% xylitol was applied on top of the pre-coating using a wire wound bar with 80 μιη wet deposit resulting in about 8 μπι dry coating layer after drying at 105°C in an oven for 3 minutes.

Migration from the board grades, with and without the xylan-based coating on top, into Tenax (modified polyphenylene oxide) at 40°C was measured according to standard DIN EN 14338. Tenax is a simulant for dry and greasy food stuffs. The Tenax was in contact with the coated side. After 10 days, the volatile substances adsorbed onto Tenax were extracted with diethyl ether and summarized by means of gas chromatography and mass spectrometric detection against deuterated nonadecane (C19) as an internal standard. For the identification of further signals in the chromatogram, a commercially available mass spectra library was used and also quantified against the internal standard. The detection limit of the overall migration was 0.1 mg/dm².

The following overall migrations were detected:

Not determinable, i.e. below the detection limit of 0.1 mg/dm². In addition, some substances could be identified for some of the samples.

For board A, saturated aliphatic hydrocarbons in amounts between 0.001 mg/dm² and 0.036 mg/dm² (in total 0.14 mg/dm²) were detected.

For board B, saturated aliphatic hydrocarbons in amounts between 0.001 mg/dm² and 0.078 mg/dm² (in total 0.34 mg/dm²) were detected. In addition, a fatty acid ester was detected in the amount 0.002 mg/dm².

For board C, the following substances could be identified:

2,2,4-trimethyl-l,3-pentanediol di-isobutyrate (TXIB)0.004 mg/dm²

Isopropyllaurat (IPL) 0.015 mg/dm²

Diisopropylnaphtalene (DIPN) 0.10 mg/dm²

Diisobutylphtalate (DIBP) 0.009 mg/dm²

Fatty acid ester 0.009 mg/dm²

As further signals, for board C, saturated aliphatic hydrocarbons in amounts between 0.001 mg/dm² and 0.021 mg/dm² (in total 0.13 mg/dm²) were detected.

For board D, the following substances could be identified:

2,2,4-trimethyl-l,3-pentanediol di-isobutyrate (TXIB)0.002 mg/dm²

Isopropyllaurat (IPL) 0.006 mg/dm²

Diisopropylnaphtalene (DIPN) 0.022 mg/dm²

Diisobutylphtalate (DIBP) 0.006 mg/dm²

Fatty acid ester 0.009 mg/dm²

As further signals, for board D, saturated aliphatic hydrocarbons in amounts between 0.001 mg/dm² and 0.022 mg/dm² (in total 0.13 mg/dm²) were detected.

For board E, the following substances could be identified:

Isopropyllaurat (IPL) 0.022 mg/dm²

Diisopropylnaphtalene (DIPN) 0.115 mg/dm²

Diisobutylphtalate (DIBP) 0.003 mg/dm²

Fatty acid ester 0.004 mg/dm² As further signals, for board E, saturated aliphatic hydrocarbons in amounts between 0.001 mg/dm² and 0.026 mg/dm² (in total 0.15 mg/dm²) were detected.

For board F, the following substances could be identified:

Isopropyllaurat (IPL) 0.022 mg/dm²

2,2,4-trimethyl-l,3-pentanediol di-isobutyrate (TXIB)0.003 mg/dm²

Diisopropylnaphtalene (DIPN) 0.02 mg/dm²

Fatty acid ester 0.01 mg/dm² As further signals, for board F, saturated aliphatic hydrocarbons in amounts between 0.001 mg/dm² and 0.023 mg/dm² (in total 0.14 mg/dm²) were detected.

For the coated board grades, only board D, E and F showed signals. From coated board D traces of a saturated aliphatic hydrocarbon, in total 0.001 mg/dm², had migrated.

From coated board E, the following substances could be identified:

Isopropyllaurat (IPL) 0.012 mg/dm²

Diisopropylnaphtalene (DIPN) 0.011 mg/dm²

As further signals, for coated board E, saturated aliphatic hydrocarbons in a total amount of 0.003 mg/dm² were detected. From coated board F, the following substances could be identified:

Isopropyllaurat (IPL) 0.013 mg/dm²

Fatty acid ester 0.001 mg/dm²

As further signals, for coated board F, saturated aliphatic hydrocarbons in total amount of 0.004 mg/dm² were detected.

It is clear that a xylan-based coating onto recycled board qualities acts as a very efficient migration barrier and hinders the migration of substances from the recycled board. This result was obtained for all the different tested recycled board qualities.

Example 2 This example illustrates the production of a xylan-based coating onto aluminum foil and measurement of the migration from the xylan-based coating to the food simulant.

A pre-coating based on styrene butadiene-latex was applied onto the aluminum foil using a wire wound bar with 24 μιη wet deposit resulting in about 12 μιη dry coating layer after drying at 105°C in an oven for 3 minutes. A xylan-based coating containing 70% arabinoxylan isolated from barley husks and 30% xylitol was applied on top of the pre-coating using a wire wound bar with 80 μιη wet deposit resulting in about 8 μιη dry coating layer after drying at 105°C in an oven for 3 minutes.

Migration from the xylan-based coating into Tenax (modified polyphenylene oxide) at 40°C was measured according to standard DIN EN 14338. Tenax is a simulant for dry and greasy food stuffs. The Tenax was in contact with the coating. After 10 days, the volatile substances absorbed onto tenax were extracted with diethyl ether and summarized by means of gas chromatography and mass spectrometric detection against deuterated nonadecane (C19) as an internal standard. For the identification of further signals in the chromatogram, a commercially available mass spectra library was used and also quantified against the internal standard. The overall migration detected was below the detection limit, i.e. <0.1 mg/dm² and no signals were found. Thus, it is clear that the xylan-based coating itself does not cause migration of substances into the food stuffs to be packed.

Example 3

This example illustrates the use of a xylan-based coating layer with different plasticizers as a migration barrier on recycled board.

The following board grade was used in the experiments. Board E: Serviboard GD2 from RenoDeMedici, a fully white lined chipboard, grey back, with 300 g/m².

A pre-coating based on styrene butadiene-latex was applied onto board E using a wire wound bar with 24 μπι wet deposit resulting in about 12 μπι dry coating layer after drying at 105°C in an oven for 3 minutes. A xylan-based coating containing

arabinoxylan isolated from barley husks and plasticizer was applied on top of the pre- coating using a wire wound bar with 80 μπι wet deposit resulting in about 8 μπι dry coating layer after drying at 105°C in an oven for 3 minutes. Different plasticizers and amounts of plasticizer were used according to the table below.

Migration from board E, with and without the xylan-based coatings on top, into Tenax (modified polyphenylene oxide) at 40°C was measured according to standard DIN EN 14338. Tenax is a simulant for dry and greasy food stuffs. The Tenax was in contact with the coated side. After 10 days, the volatile substances adsorbed onto Tenax were extracted with diethyl ether and summarized by means of gas chromatography and mass spectrometric detection against deuterated nonadecane (C19) as an internal standard. For the identification of further signals in the chromatogram, a commercially available mass spectra library was used and also quantified against the internal standard. The detection limit of the overall migration was 0.1 mg/dm².

¹ Not determinable, i.e. below the detection limit of 0.1 mg/dm².

² Xylan content replaced by xylan: starch, 2:1.

These results clearly show that different kinds of plasticizers can be used in the migration barrier coating layer. Also, different amounts of plasticizer can be used well as combinations of different plasticizers.

Example 4 This example illustrates the use of a xylan-based coating layer without any added external plasticizer other than water as a migration barrier on recycled board.

A pre-coating based on styrene butadiene-latex was applied onto board E using a wire wound bar with 24 μιη wet deposit resulting in about 12 μιη dry coating layer after drying at 105°C in an oven for 3 minutes. A xylan-based coating containing

arabinoxylan isolated from barley husks in water was applied on top of the pre-coating using a wire wound bar with 80 μιη wet deposit resulting in about 8 μιη dry coating layer after drying at 105°C in an oven for 3 minutes.

Migration from board E, with and without the xylan-based coating on top, into Tenax (modified polyphenylene oxide) at 40°C was measured according to standard DIN EN 14338. Tenax is a simulant for dry and greasy food stuffs. The Tenax was in contact with the coated side. After 10 days, the volatile substances adsorbed onto Tenax were extracted with diethyl ether and summarized by means of gas chromatography and mass spectrometric detection against deuterated nonadecane (C19) as an internal standard. For the identification of further signals in the chromatogram, a commercially available mass spectra library was used and also quantified against the internal standard. The detection limit of the overall migration was 0.1 mg/dm².

The following overall migrations were detected:

1 Not determinable, i.e. below the detection limit of 0.1 mg/dm².

These results show that even a coating layer without added external plasticizer other than water provides an excellent migration barrier on recycled board.

Example 5

This example illustrates the use of a xylan-based migration barrier on recycled board at different temperatures. The following board grade was used in the experiments. Board E: Serviboard GD2 from RenoDeMedici, a fully white lined chipboard, grey back, with 300 g/m². A pre-coating based on styrene butadiene-latex was applied onto board E using a wire wound bar with 24 μιη wet deposit resulting in about 12 μιη dry coating layer after drying at 105°C in an oven for 3 minutes. A xylan-based coating containing 70% arabinoxylan isolated from barley husks and 30% xylitol was applied on top of the pre- coating using a wire wound bar with 80 μιη wet deposit resulting in about 8 μιη dry coating layer after drying at 105°C in an oven for 3 minutes.

Migration from board E, with and without the xylan-based coatings on top, into Tenax (modified polyphenylene oxide) at 40°C and 60°C was measured according to standard DIN EN 14338. Tenax is a simulant for dry and greasy food stuffs. The Tenax was in contact with the coated side. After 10 days, the volatile substances adsorbed onto Tenax were extracted with diethyl ether and summarized by means of gas chromatography and mass spectrometric detection against deuterated nonadecane (C19) as an internal standard. For the identification of further signals in the chromatogram, a commercially available mass spectra library was used and also quantified against the internal standard. The detection limit of the overall migration was 0.1 mg/dm².

The following overall migrations were detected:

Not determinable, i.e. below the detection limit of 0.1 mg/dm².

In addition, some substances could be identified for the sampl

For board E, the following substances could be identified after 10 days at 40°C:

Isopropyllaurat (IPL) 0.022 mg/dm²

Diisopropylnaphtalene (DIPN) 0.115 mg/dm²

Diisobutylphtalate (DIBP) 0.003 mg/dm²

Fatty acid ester 0.004 mg/dm² As further signals, for board E after 10 days at 40°C, saturated aliphatic hydrocarbons amounts between 0.001 mg/dm² and 0.026 mg/dm² (in total 0.15 mg/dm²) were detected.

From coated board E, the following substances could be identified after 10 days at

40°C:

Isopropyllaurat (IPL) 0.012 mg/dm²

Diisopropylnaphtalene (DIPN) 0.011 mg/dm²

As further signals, for coated board E after 10 days at 40°C, saturated aliphatic hydrocarbons in a total amount of 0.003 mg/dm² were detected.

For board E, the following substances could be identified after 10 days at 60°C: Alkenes and traces of alkylbenzene 0.070 mg/dm²

Isopropyllaurat (IPL) 0.031 mg/dm²

Diisopropylnaphtalene (DIPN) 0.186 mg/dm²

Diisobutylphtalate (DIBP) 0.005 mg/dm²

Fatty acid ester 0.015 mg/dm²

Di-(2-ethylhexyl)adipate (DEHA) 0.007 mg/dm²

Ethylhexyl phtalate (EHP) 0.018 mg/dm²

As further signals, for board E after 10 days at 60°C, saturated aliphatic hydrocarbons total amount of 0.156 mg/dm² were detected.

From coated board E, the following substances could be identified after 10 days at 60°C:

Alkenes and traces of alkylbenzene 0.064 mg/dm²

Isopropyllaurat (IPL) 0.005 mg/dm²

Diisopropylnaphtalene (DIPN) 0.020 mg/dm²

As further signals, for coated board E after 10 days at 60°C, saturated aliphatic hydrocarbons in total amount of 0.015 mg/dm² were detected. These results show that the xylan-based coating layer acts as an efficient migration barrier also at tougher conditions, such as elevated temperature. Example 6

This example illustrates the migration from recycled fibers through xylan-based coating layers of different thicknesses.

A pre-coating based on styrene butadiene-latex was applied onto board E using a wire wound bar with 24 μπι and 12 μπι wet deposit resulting in about 12 μπι and 6 μπι dry coating layer after drying at 105°C in an oven for 3 minutes. A xylan-based coating containing 70% arabinoxylan isolated from barley husks and 30% xylitol was applied on top of the pre-coating using a wire wound bar with 80 μπι, 50 μπι and 24 μπι wet deposit resulting in about 8 μπι, 5 μπι and 2 μπι dry coating layer after drying at 105°C in an oven for 3 minutes.

The following overall migrations were detected:

12 μηι pre-coating

Xylan-coated board E with 2 0.15

12 μιη pre-coating

Not determinable, i.e. below the detection limit of 0.1 mg/dm².

In addition, some substances could be identified for the samples. For board E, the following substances could be identified after 10 days at 40°C:

Isopropyllaurat (IPL) 0.022 mg/dm²

Diisopropylnaphtalene (DIPN) 0.115 mg/dm²

Diisobutylphtalate (DIBP) 0.003 mg/dm²

Fatty acid ester 0.004 mg/dm²

As further signals, for board E after 10 days at 40°C, saturated aliphatic hydrocarbons in amounts between 0.001 mg/dm² and 0.026 mg/dm² (in total 0.15 mg/dm²) were detected. From coated board E, with a 6 μπι thick pre-coating and a 5 μπι thick xylan-based coating, after 10 days at 40°C, saturated aliphatic hydrocarbons in total amount of 0.006 mg/dm² were detected.

From coated board E, with a 6 μπι thick pre-coating and a 2 μπι thick xylan-based coating, after 10 days at 40°C, saturated aliphatic hydrocarbons in total amount of 0.037 mg/dm² were detected.

From coated board E, with a 12 μπι thick pre-coating and an 8 μπι thick xylan-based coating, the following substances could be identified after 10 days at 40°C:

Isopropyllaurat (IPL) 0.012 mg/dm²

Diisopropylnaphtalene (DIPN) 0.011 mg/dm²

As further signals, for coated board E, with a 12 μπι thick pre-coating and an 8 μπι thick xylan-based coating, after 10 days at 40°C, saturated aliphatic hydrocarbons in a total amount of 0.003 mg/dm² were detected.

From coated board E, with a 12 μπι thick pre-coating and a 5 μπι thick xylan-based coating, the following substances could be identified after 10 days at 40°C:

Isopropyllaurat (IPL) 0.005 mg/dm² Diisopropylnaphtalene (DIPN) 0.002 mg/dm²

As further signals, for coated board E, with a 12 μιη thick pre-coating and a 5 μιη thick xylan-based coating, after 10 days at 40°C, saturated aliphatic hydrocarbons in total amount of 0.007 mg/dm² were detected.

From coated board E, with a 12 μιη thick pre-coating and a 2 μιη thick xylan-based coating, the following substances could be identified after 10 days at 40°C:

Isopropyllaurat (IPL) 0.010 mg/dm²

Diisopropylnaphtalene (DIPN) 0.022 mg/dm²

As further signals, for coated board E, with a 12 μπι thick pre-coating and a 2 μπι thick xylan-based coating, after 10 days at 40°C, saturated aliphatic hydrocarbons in total amount of 0.032 mg/dm² were detected.

The xylan-based coating layer acts as an efficient migration barrier also when coating layers even thinner than 8 μπι, such as 5 μπι or even 2 μπι, are used.

Example 7

This example illustrates the migration through xylan-based coating layers with and without a pre-coating layer and the migration from a board that is coated with just the pre-coating layer. Tests have shown that in some cases better results can be obtained when using a pre- coating layer to coat onto. The pre-coating creates a more homogeneous and smooth surface. Also, the tendency of an aqueous coating slurry to sink into the substrate can be reduced by using a pre-coating. As a result, a thinner coating layer can sometimes be used to obtain barrier properties if a pre-coating layer has been applied underneath.

A pre-coating based on styrene butadiene-latex was applied onto board E using a wire wound bar with 24 μπι wet deposit resulting in about 12 μπι dry coating layer after drying at 105°C in an oven for 3 minutes. A xylan-based coating containing 70% arabinoxylan isolated from barley husks and 30% xylitol was applied on top of the pre- coating using a wire wound bar with 80 μιη wet deposit resulting in about 8 μιη dry coating layer after drying at 105°C in an oven for 3 minutes. A xylan-based coating containing 70% arabinoxylan isolated from barley husks and 30% xylitol was also applied directly onto board E using a wire wound bar with 80 μιη and 50 μιη wet deposit resulting in about 8 μιη and 5 μιη dry coating layer after drying at 105°C in an oven for 3 minutes. Some samples of board E with just the pre-coating were also analyzed.

Migration from board E without additional coating, with just the pre-coating, with just the xylan-based coating and with both pre-coating and xylan-based coating into Tenax (modified polyphenylene oxide) at 40°C was measured according to standard DIN EN 14338. Tenax is a simulant for dry and greasy food stuffs. The Tenax was in contact with the coated side. After 10 days, the volatile substances adsorbed onto Tenax were extracted with diethyl ether and summarized by means of gas chromatography and mass spectrometric detection against deuterated nonadecane (C19) as an internal standard. For the identification of further signals in the chromatogram, a commercially available mass spectra library was used and also quantified against the internal standard. The detection limit of the overall migration was 0.1 mg/dm². The following overall migrations were detected:

Not determinable, i.e. below the detection limit of 0.1 mg/dm².

In addition, some substances could be identified for the samples.

For board E without additional coating, the following substances could be identified after 10 days at 40°C:

Isopropyllaurat (IPL) 0.022 mg/dm²

Diisopropylnaphtalene (DIPN) 0.115 mg/dm²

Diisobutylphtalate (DIBP) 0.003 mg/dm² Fatty acid ester 0.004 mg/dm²

As further signals, for board E without additional coating after 10 days at 40°C, saturated aliphatic hydrocarbons in amounts between 0.001 mg/dm² and 0.026 mg (in total 0.15 mg/dm²) were detected.

From board E with just the pre-coating, the following substances could be identified after 10 days at 40°C:

Isopropyllaurat (IPL) 0.024 mg/dm²

Diisopropylnaphtalene (DIPN) 0.118 mg/dm²

Diisobutylphtalate (DIBP) 0.005 mg/dm²

Fatty acid ester 0.017 mg/dm²

Ethylhexyl phthalate (EHP) 0.008 mg/dm² As further signals, for board E with just the pre-coating, after 10 days at 40°C, saturated aliphatic hydrocarbons in total amount of 0.093 mg/dm² were detected.

From board E with just the 5 μπι thick xylan-based coating, after 10 days at 40°C, saturated aliphatic hydrocarbons in total amount of 0.006 mg/dm² were detected.

From board E with just the 8 μπι thick xylan-based coating, the following substances could be identified after 10 days at 40°C:

Isopropyllaurat (IPL) 0.002 mg/dm²

Diisopropylnaphtalene (DIPN) 0.005 mg/dm²

As further signals, for board E with just the 8 μπι thick xylan-based coating, after 10 days at 40°C, saturated aliphatic hydrocarbons in total amount of 0.007 mg/dm² were detected. From board E with pre-coating and 8 μπι xylan-based coating, the following substances could be identified after 10 days at 40°C:

Isopropyllaurat (IPL) 0.012 mg/dm²

Diisopropylnaphtalene (DIPN) 0.011 mg/dm²

As further signals, for board E with pre-coating and 8 μπι xylan-based coating, after 10 days at 40°C, saturated aliphatic hydrocarbons in total amount of 0.003 mg/dm² were detected. This example clearly illustrates that the pre-coating in itself does not act as a migration barrier on the recycled board. It was surprisingly found that even without the pre- coating layer underneath, the xylan-based coating is a very efficient migration barrier. A coating layer of only 8 μπι or 5 μπι is enough to reduce the overall migration from the recycled board to a value below the detection limit, and it may be assumed that even thinner layers, e.g. less than 2 μπι in some applications may suffice to form an efficient migration barrier.

Example 8

This example illustrates the migration from recycled board through an LDPE coating layer. The following board grade was used in the experiments. Board E: Serviboard GD2 from RenoDeMedici, a fully white lined chipboard, grey back, with 300 g/m².

The board was extrusion coated with a 20 μπι thick layer of LDPE CA7230 from Borealis.

Migration from board E with and without LDPE coating into Tenax (modified polyphenylene oxide) at 40°C was measured according to standard DUST EN 14338. Tenax is a simulant for dry and greasy food stuffs. The Tenax was in contact with the coated side. After 10 days, the volatile substances adsorbed onto Tenax were extracted with diethyl ether and summarized by means of gas chromatography and mass spectrometric detection against deuterated nonadecane (C19) as an internal standard. For the identification of further signals in the chromatogram, a commercially available mass spectra library was used and also quantified against the internal standard.

The following overall migrations were detected:

In addition, some substances could be identified for the samples. For board E without additional coating, the following substances could be identified after 10 days at 40°C:

Isopropyllaurat (IPL) 0.022 mg/dm²

Diisopropylnaphtalene (DIPN) 0.115 mg/dm²

Diisobutylphtalate (DIBP) 0.003 mg/dm²

Fatty acid ester 0.004 mg/dm²

As further signals, for board E without additional coating after 10 days at 40°C, saturated aliphatic hydrocarbons in amounts between 0.001 mg/dm² and 0.026 mg/dm² (in total 0.15 mg/dm²) were detected.

From board E with LDPE coating, the following substances could be identified after 10 days at 40°C:

Isopropyllaurat (IPL) 0.022 mg/dm²

Diisopropylnaphtalene (DIPN) 0.167 mg/dm²

Fatty acid ester 0.011 mg/dm²

As further signals, for board E with LDPE coating, after 10 days at 40°C, saturated aliphatic hydrocarbons in total amount of 0.097 mg/dm² were detected.

This example clearly illustrates that LDPE does not act as a migration barrier when applied onto recycled board.

Example 9

This example illustrates the migration through xylan-based coating layers of different origin.

A pre-coating based on styrene butadiene-latex was applied onto the different board grades using a wire wound bar with 24 μπι wet deposit resulting in about 12 μπι dry coating layer after drying at 105°C in an oven for 3 minutes. A xylan-based coating containing 70% arabinoxylan isolated from barley husks and 30% xylitol was applied on top of the pre-coating using a wire wound bar with 80 μπι wet deposit resulting in about 8 μπι dry coating layer after drying at 105°C in an oven for 3 minutes. A xylan- based coating containing 70% arabinoxylan isolated from wheat and 30% xylitol was applied on top of the pre-coating using a wire wound bar with 80 μιη wet deposit resulting in about 8 μιη dry coating layer after drying at 105°C in an oven for 3 minutes. A xylan-based coating containing 70% glucuronoxylan isolated from aspen and 30% xylitol was applied on top of the pre-coating using a wire wound bar with 80 μιη wet deposit resulting in about 8 μιη dry coating layer after drying at 105°C in an oven for 3 minutes.

Migration from board E, with and without xylan-based coating, into Tenax (modified polyphenylene oxide) at 40°C was measured according to standard DIN EN 14338. Tenax is a simulant for dry and greasy food stuffs. The Tenax was in contact with the coated side. After 10 days, the volatile substances adsorbed onto Tenax were extracted with diethyl ether and summarized by means of gas chromatography and mass spectrometric detection against deuterated nonadecane (C19) as an internal standard. For the identification of further signals in the chromatogram, a commercially available mass spectra library was used and also quantified against the internal standard. The detection limit of the overall migration was 0.1 mg/dm².

The following overall migrations were detected:

1 Not determinable, i.e. below the detection limit of 0.1 mg/dm².

In addition, some substances could be identified for some of the samples.

Isopropyllaurat (IPL) 0.022 mg/dm²

Diisopropylnaphtalene (DIPN) 0.115 mg/dm²

Diisobutylphtalate (DIBP) 0.003 mg/dm²

Fatty acid ester 0.004 mg/dm² As further signals, for board E without additional coating after 10 days at 40°C, saturated aliphatic hydrocarbons in amounts between 0.001 mg/dm² and 0.026 mg/dm² (in total 0.15 mg/dm²) were detected. From board E with barley xylan-based coating, the following substances could be identified after 10 days at 40°C:

Isopropyllaurat (IPL) 0.012 mg/dm²

Diisopropylnaphtalene (DIPN) 0.011 mg/dm² As further signals, for board E with barley xylan-based coating, after 10 days at 40°C, saturated aliphatic hydrocarbons in total amount of 0.003 mg/dm² were detected.

From board E with wheat xylan-based coating and aspen xylan-based coating, no signals could be detected.

These results show that xylans from different sources can be used to provide an excellent migration barrier onto recycled board.

Example 10

This example illustrates the migration through a xylan-based coating layer containing an inorganic filler.

A pre-coating based on styrene butadiene-latex was applied onto the different board grades using a wire wound bar with 24 μπι wet deposit resulting in about 12 μπι dry coating layer after drying at 105°C in an oven for 3 minutes. A xylan-based coating containing 35% arabinoxylan isolated from barley husks, 15% xylitol and 50% inorganic filler was applied on top of the pre-coating using a wire wound bar with 50 μπι wet deposit resulting in about 8 μπι dry coating layer after drying at 105°C in an oven for 3 minutes. Different inorganic fillers were evaluated; kaolin clay, calcium carbonate and talc.

Migration from board E with and without xylan-based coating into Tenax (modified polyphenylene oxide) at 40°C was measured according to standard DIN EN 14338. Tenax is a simulant for dry and greasy food stuffs. The Tenax was in contact with the coated side. After 10 days, the volatile substances adsorbed onto Tenax were extracted with diethyl ether and summarized by means of gas chromatography and mass spectrometric detection against deuterated nonadecane (C19) as an internal standard. For the identification of further signals in the chromatogram, a commercially available mass spectra library was used and also quantified against the internal standard. The detection limit of the overall migration was 0.1 mg/dm².

The following overall migrations were detected:

Not determinable, i.e. below the detection limit of 0.1 mg/dm².

In addition, some substances could be identified for some of the samples.

Isopropyllaurat (IPL) 0.022 mg/dm²

Diisopropylnaphtalene (DIPN) 0.115 mg/dm²

Diisobutylphtalate (DIBP) 0.003 mg/dm²

Fatty acid ester 0.004 mg/dm²

As further signals, for board E without additional coating after 10 days at 40°C, saturated aliphatic hydrocarbons in amounts between 0.001 mg/dm² and 0.026 mg/dm² (in total 0.15 mg/dm²) were detected. From board E with barley xylan-based coating with talc, the following substances could be identified after 10 days at 40°C:

Isopropyllaurat (IPL) 0.001 mg/dm²

As further signals, for board E with barley xylan-based coating with talc, after 10 days at 40°C, saturated aliphatic hydrocarbons in total amount of 0.001 mg/dm² were detected. For board E with a xylan-based coating with kaolin and for board E with xylan-based coating with calcium carbonate, no signals could be detected.

These results clearly show that the migration barrier properties of the xylan-based coatings are preserved after the addition of a filler. In this example, a high filler content is used, 50%. A lower filler content can also be used to produce a xylan-based migration barrier coating layer. One advantage when using a filler is that the dry content of the aqueous slurry can be increased with minor increase on the viscosity of the slurry. Thus, it is possible to either apply a thicker coating with remaining amount of water to dry off or to apply the same amount of material with a lower amount of water to dry off. Drying capacity is often a limiting factor when applying aqueous dispersions since the drying time is limited in industrial coating equipment. Also, drying is an energy demanding process. A further advantage with using filler is that the cost of the coating layer can be reduced.

Example 11

This example illustrates the migration through a glucomannan-based coating layer.

A pre-coating based on styrene butadiene-latex was applied onto the different board grades using a wire wound bar with 24 μπι wet deposit resulting in about 12 μπι dry coating layer after drying at 105°C in an oven for 3 minutes. A glucomannan-based coating containing 70% konjac glucomannan purchased from Megazymes and 30% xylitol was applied on top of the pre-coating using a wire wound bar with 100 μπι wet deposit resulting in about 8 μπι dry coating layer after drying at 105°C in an oven for 3 minutes.

Migration from board E with and without glucomannan-based coating into Tenax (modified polyphenylene oxide) at 40°C was measured according to standard DIN EN 14338. Tenax is a simulant for dry and greasy food stuffs. The Tenax was in contact with the coated side. After 10 days, the volatile substances adsorbed onto Tenax were extracted with diethyl ether and summarized by means of gas chromatography and mass spectrometric detection against deuterated nonadecane (C19) as an internal standard. For the identification of further signals in the chromatogram, a commercially available mass spectra library was used and also quantified against the internal standard. The detection limit of the overall migration was 0.1 mg/dm². The following overall migrations were detected:

Not determinable, i.e. below the detection limit of 0.1 mg/dm².

Isopropyllaurat (IPL) 0.022 mg/dm²

Diisopropylnaphtalene (DIPN) 0.115 mg/dm²

Diisobutylphtalate (DIBP) 0.003 mg/dm²

Fatty acid ester 0.004 mg/dm² As further signals, for board E without additional coating after 10 days at 40°C, saturated aliphatic hydrocarbons in amounts between 0.001 mg/dm² and 0.026 mg/dm² (in total 0.15 mg/dm²) were detected.

From board E with glucomannan-based coating, no signals could be detected.

These results clearly show that the invention can be carried out with different types of hemicelluloses, including glucomannan.

Example 12

This example illustrates the migration through a xylan-based coating layer when using isooctane as the simulant.

A pre-coating based on styrene butadiene -latex was applied onto the different board grades using a wire wound bar with 24 μπι wet deposit resulting in about 12 μπι dry coating layer after drying at 105°C in an oven for 3 minutes. A xylan-based coating containing 70% arabinoxylan isolated from barley husks and 30% sorbitol was applied on top of the pre-coating using a wire wound bar with 80 μιη wet deposit resulting in about 8 μπι dry coating layer after drying at 105°C in an oven for 3 minutes.

Migration from the board grades with and without the xylan-based coating on top into isooctane at 20°C for 2 days was measured. Isooctane is a simulant for dry and greasy food stuffs. The determination was carried out according to the methods for the "Examination of consumer goods" corresponding to the directives B 80.30, 1 to 3 (EG) of the Official Collection of Analytical Methods according to § 64 LFGB and according to the rules of the series of standards EN 1186, EN 13130 and CEN/TS 14234

"Materials and articles in contact with foodstuffs - Plastics". The isooctane was in contact with the coated side. The measurements were done in triplicate. The following overall migrations were detected:

¹ Not determinable, i.e. below the detection limit of 2 mg/dm².

These results show that different simulants for food stuffs can be used when measuring the migration barrier performance of the coating layers.

Example 13

This example illustrates the migration through a xylan-based coating layer at elevated relative humidity.

A pre-coating based on styrene butadiene-latex was applied onto the different board grades using a wire wound bar with 24 μπι wet deposit resulting in about 12 μπι dry coating layer after drying at 105°C in an oven for 3 minutes. A xylan-based coating containing 35% arabinoxylan isolated from barley husks, 15% xylitol and 50% inorganic filler was applied on top of the pre-coating using a wire wound bar with 50 μηι wet deposit resulting in about 8 μιη dry coating layer after drying at 105°C in an oven for 3 minutes.

Migration from board E with and without xylan-based coating into Tenax (modified polyphenylene oxide) at 40°C was measured according to standard DIN EN 14338. The samples were kept at an elevated relative humidity (RH) of 70%. Tenax is a simulant for dry and greasy food stuffs. The Tenax was in contact with the coated side. After 10 days, the volatile substances adsorbed onto Tenax were extracted with diethyl ether and summarized by means of gas chromatography and mass spectrometric detection against deuterated nonadecane (C19) as an internal standard. For the identification of further signals in the chromatogram, a commercially available mass spectra library was used and also quantified against the internal standard. The detection limit of the overall migration was 0.05 mg/dm². The following overall migrations were detected:

In addition, some substances could be identified for some of the samples.

For board E without additional coating, the following substances could be identified after 10 days at 40°C and 70 % RH:

Isopropyllaurat (IPL) 0.0070 mg/dm²

Diisopropylnaphtalene (DIPN) 0.0177 mg/dm²

Diisobutylphtalate (DIBP) 0.0046 mg/dm²

Fatty acid methylester 0.0084 mg/dm²

Ethylhexyl phthalate (EHP) 0.0142 mg/dm²

As further signals, for board E without additional coating after 10 days at 40°C and 70 RH, saturated aliphatic hydrocarbons in total amount of 0.1080 mg/dm² were detected.

From board E with barley xylan-based coating, after 10 days at 40°C and 70 % RH, saturated aliphatic hydrocarbons in total amount of 0.0122 mg/dm² were detected. These results show that the xylan-based coating layer acts as an efficient migration barrier also at elevated RH.

INDUSTRIAL APPLICABILITY

An advantage of the present invention is that the film or coating is biodegradable, which facilitates recycling.

A further advantage is that the material is based on renewable resources, which is favorable from an environmental point of view.

A further advantage is that the films or coatings according to the present invention are based on renewable resources, which can be extracted from low value by-products from wood and agricultural residues. The films and coatings therefore have a great potential to be cost efficient in large scale production volumes.

The price of crude oil has increased a lot lately and is expected to increase even further in the future. This has further led to a great increase of prices of synthetic plastic materials. Since the films and coatings according to the present invention are based on renewable resources they are less sensitive to oil prices and the cost efficiency can be even more important in the future.

A further advantage is that the present invention increases the possibility to use recycled paper and board in food packaging. The hemicellulose-based coating is repulpable which means that waste from paper and board production could be reused in the production process.

Claims

1. A film or coating for preventing migration of substances from paper or board containing recycled fibers, characterized in that said film or coating is a polymeric film or coating comprising hemicellulose, wherein said film or coating is arranged to form a migration barrier layer with a thickness equal to or less than 50 μπι, preferably between 1-25 μπι, more preferably between 1-20 μπι, even more preferably between 1-15 μπι, even more preferably between 2- 15 μπι, even more preferably between 2-10 μπι and most preferably between 2- 5 μπι or 5 - 10 μπι.

2. The film or coating according to claim 1, further comprising plasticizer.

3. The film or coating according to claim 1 or 2, further comprising filler.

The film or coating according to claim 2 or 3, wherein said plasticizer is selected from the group consisting of water, citric acid, sugars, glycerol, xylitol, sorbitol and maltitol, ethylene glycol, propylene glycol, butanediol, glycerine and urea.

The film or coating according to claim 3, wherein said filler is selected from the group consisting of silica, talc, clay, calcium carbonate, mica, kaolin, wollastonite, montmorillonite, feldspar, barytes, glass fibers and carbon fibers.

The film or coating according to anyone of the previous claims, arranged to prevent the overall migration of substances from paper or board containing recycled fibers by at least 80%, preferably by at least 90%.

The film or coating according to anyone of the previous claims, arranged to prevent migration of at least one substance selected from a group consisting of: primary aromatic amines, 4, 4'-bis(dimethylamino)-benzophenone, phthalates, benzophenone, bisphenol A, aliphatic hydrocarbons, 2,2,4-trimethyl-l,3- pentanediol di-isobutyrate (TXIB), isopropyllaurat (IPL), diisopropylnaphtalene (DIPN), and fatty acid esters.

8. The film or coating according to anyone of the previous claims, wherein said film or coating has a hemicellulose content in % by dry weight of 10- 100 %, preferably 20 -70 %.

9. The film or coating according to anyone of the previous claims, further comprising starch, where preferably the content in dry % by weight of hemicellulose in relation to the content in dry % by weight of starch is in the range of 2: 1 to 1 : 1.

10. The film or coating according to anyone of the previous claims, wherein said hemicellulose is arabinoxylan, or glucuronoxylan or glucomannan.

11. A paper or board laminate, comprising a film or coating according to claim 1, wherein said paper or board substrate comprises at least 25 % recycled fibers, preferably at least 50% and more preferred at least 75% in dry % by weight.

12. A paper or board laminate according to claim 11, wherein said paper or board substrate has a grammage above 100 g/m² and the amount of filler is between 10-60 %, preferably 20 - 50% in dry % by weight.

13. A paper or board laminate according to claim 11, wherein said film or coating has a hemicellulose content in % by dry weight of 10-40 %.

14. A paper or board laminate according to claim 13, wherein said paper or board substrate has a grammage above 200 g/m², preferably above 300 g/m² and the amount of filler is between 30 - 60 %, preferably 30 - 50%.

15. A paper or board laminate according to claim 11, wherein said paper or board relates to a substrate having a grammage less than 100 g/m² and the amount of filler is less than 30 %, preferably less than 20%.

16. A paper or board laminate according to claim 15, wherein said film or coating has a hemicellulose content in % by dry weight of 40-70 %.

17. A paper or board laminate according to anyone of claims 11, 15 or 16 wherein said paper or board substrate has a grammage less than 100 g/m² and the amount of plasticizer is between 30-60 %, preferably 40-50%.