JP2014516884A - Paper packaging material and cardboard packaging material having a barrier coating - Google Patents

Abstract

  A paper packaging material or cardboard packaging material made of recycled paper loaded with mineral oil, wherein the packaging material is a C1-C4 alkyl (meth) acrylate, an acid monomer such as acrylic acid or methacrylic acid, acrylonitrile 0-20% by mass And a barrier layer that can be produced by applying an aqueous polymer dispersion containing a copolymer that can be produced by emulsion polymerization from 0 to 10% by weight of further monomers, wherein the glass transition temperature of the copolymer is +10 Within the range of ~ + 45 ° C. The barrier layer can be present on one of the packaging material surfaces, can form one of a plurality of layers of a multi-layer packaging material coating, or is present within the packaging material. It can be present as a coating on the side of the bag.

Description

  The present invention is a barrier that can be made by applying an aqueous polymer dispersion containing a copolymer that can be made by emulsion polymerization from C1-C4 alkyl (meth) acrylates, acid monomers and optional acrylonitrile and further monomers. With regard to a paper packaging or cardboard packaging made of recycled paper loaded with mineral oil having a layer, the glass transition temperature of the copolymer is in the range of +10 to + 45 ° C. The barrier layer can be present on one of the packaging material surfaces, or can form one of a plurality of layers of a multi-layer packaging material coating, or an inner bag present in the packaging material It can be present as a coating on one side.

  Cardboard packaging is usually manufactured from recycled paper. In the case of printed paper, in particular newspaper, the recycled paper can contain mineral oil residues from printing inks normally used for newspaper printing. Already at room temperature, the volatiles of the residue evaporate and, in the case of food packaging materials, accumulate on foods packaged in boxes, such as noodles, cereal flour, rice or corn flakes. In so doing, the majority of currently used inner bags made of polymer film do not provide sufficient protection. In research in a Zurich laboratory, mineral oil residues were detected at a significant height in foods packaged in recycled paper packaging. Volatile mineral oil components are mainly paraffinic and naphthenic hydrocarbons of health concern and are aromatic hydrocarbons, especially aromatic hydrocarbons having 15 to 25 C atoms. is there.

  Therefore, there is a need to reduce the risk of food contamination with mineral oil residues. One possibility would be to omit recycling newspapers in the manufacture of cardboard boxes for packaging food. This is not desirable for ecological reasons and is not effective due to insufficiently used quantities of new cellulose. Another solution would be to omit mineral oil in the printing ink for newspaper printing. However, this poses a technical obstacle, especially in connection with the wiping component of printing on the paper surface. In the field of packaging materials, barrier coatings for oils and fats are known. WO 2006/053849 describes coatings based on aqueous polymer compositions, for example on paper and cardboard. Said polymers actually show good barrier properties against liquid fatty substances. However, it has been found that it is not always necessary to give a good barrier effect to substances that leak in gaseous form. This is because it involves various transport mechanisms for the leaking material. In the case of liquid oils and fats, the transport takes place via fibers, in which capillary forces and surface wetting are involved. In the case of problems with gaseous invading materials, capillary action and wetting are not involved, sorption, diffusion and porosity are involved. Furthermore, the hydrocarbons, ie the fats and oils of the mineral oil component, are distinguished in terms of their polarity and thereby in terms of the diffusion behavior of the fats and oils through the barrier layer.

WO 2006/053849

  The present invention is based on the problem of providing a packaging material that reduces the risk of packaging being contaminated with volatile mineral oil components despite the use of recycled paper loaded with mineral oil.

This object is achieved according to the invention by a paper or cardboard packaging material, wherein the packaging material is manufactured from recycled paper at least partially loaded with mineral oil, and the packaging material is at least one Having at least one barrier layer, which can be produced by applying an aqueous polymer dispersion containing the copolymer,
(A) one or more main monomers selected from the group consisting of C1-C4 alkyl (meth) acrylates,
(B) one or more acid monomers, for example selected from acrylic acid and methacrylic acid, 0.1 to 5% by weight,
(C) can be prepared by emulsion polymerization from 0 to 20% by weight of acrylonitrile and from 0 to 10% by weight of additional monomers, different from (d) monomers (a) to (c), the glass transition temperature of the copolymer being , In the range of +10 to + 45 ° C., wherein the barrier layer may be present on at least one of the packaging material surfaces, or the barrier layer may be a plurality of layers of a multilayer packaging material coating. Or the barrier layer is solved by the packaging material, which can be present as a coating on at least one side of the inner bag present in the packaging material. The packaging material is particularly suitable for food.

  Loaded with mineral oil means that the paper has volatile hydrocarbons in an amount detectable by conventional analytical methods, in particular volatile paraffins, volatile naphthenes and / or up to 25 C atoms. Means containing hydrocarbons. Volatile hydrocarbons are volatile hydrocarbons having up to 25 C atoms, for example 5 to 22 C atoms. In an embodiment of the invention, the mineral oil load is derived from the printing ink and includes volatile paraffins, volatile naphthenes and / or volatile aromatic hydrocarbons.

  Hereinafter, the name “(meth) acryl” and similar names are used as a shorthand notation for “acryl .... or methacryl ...”.

According to the invention, the polymer dispersion to be used is a dispersion of the polymer in an aqueous medium. This may for example be completely desalted water or a mixture of water and a solvent miscible with this water, for example methanol, ethanol or tetrahydrofuran. In particular, no organic solvent is used. The solids content of the dispersion is in particular 15 to 75, preferably 40 to 60, in particular more than 50. The solids content can be generated, for example, by correspondingly adjusting the amount of water and / or monomer used in the emulsion polymerization. The average particle size of the polymer particles dispersed in the aqueous dispersion is in particular less than 400 nm, in particular less than 300 nm. Particularly preferably, the average particle size is 70 to 250 nm or 80 to 150 nm. Here, the average particle size is taken to be the d ₅₀ value of the particle size distribution, ie 50% by mass of the total mass of all particles has a particle size smaller than the d ₅₀ value. The particle size distribution can be measured with an analytical ultracentrifuge (W. Maechtie, Makromolekule Chemie 185 (1984), pages 1025 to 1039) by a known method. The pH value of the polymer dispersion is adjusted in particular to a pH above 4, in particular from 5 to 9.

  The copolymer to be used according to the present invention is an emulsion polymer which can be produced by emulsion polymerization of a radically polymerizable monomer. The copolymer is formed from one or more main monomers (a) selected from the group consisting of C1-C4 alkyl (meth) acrylates. The main monomer (a) is used in particular at least 70% by weight, preferably at least 75% by weight, for example 79.5-99.5% by weight, based on the sum of all monomers. Particularly preferred main monomers (a) are selected from the group consisting of methyl acrylate, methyl methacrylate, ethyl acrylate and n-butyl acrylate.

  The copolymer is formed from one or more acid monomers (b). The acid monomer is an ethylenically unsaturated radically polymerizable monomer having at least one acid group, such as a monomer having a carboxylic acid group, a sulfonic acid group or a phosphonic acid group. Carboxylic acid groups are preferred. For example, acrylic acid, methacrylic acid, itaconic acid, maleic acid or fumaric acid can be mentioned. Acid monomers (b) selected from acrylic acid and methacrylic acid are preferred. The acid monomer (b) is used in an amount of 0.1 to 5% by weight, preferably 0.5 to 5% by weight, based on the sum of all monomers.

  The copolymer may optionally be formed as acrylonitrile from 0 to 20% by weight, based on the sum of all monomers, as further monomer (c). In an embodiment of the invention, the copolymer is formed from 1-20% by weight, in particular 2-20% by weight, from acrylonitrile.

  Said copolymer may optionally be formed from a further monomer (d) which is different from the monomers (a) to (c). In that case, the amount of the further monomer (d) is 0 to 10% by weight or 0 to 5% by weight, based on the sum of all monomers. In one embodiment, 0.1 to 10% by weight or 0.1 to 5% by weight of further monomer (d) is used. In another embodiment, no further monomers are used, which are different from the monomers (a) to (c).

Further monomers (d) are different from C _{5 to} C ₂₀ alkyl (meth) acrylates, vinyl esters of carboxylic acids containing up to 20 C atoms, vinyl aromatic compounds having up to 20 C atoms, acrylonitrile. Ethylenically unsaturated nitriles, vinyl halides, vinyl ethers of alcohols containing 10 to 10 C atoms, aliphatic hydrocarbons having 2 to 8 C atoms and 1 or 2 double bonds, or of the above monomers It may be selected from the group consisting of mixtures. For example, C ₅ -C ₁₀ having an alkyl group (meth) acrylic acid alkyl ester may include, for example 2-ethylhexyl acrylate. In particular, mixtures of (meth) acrylic acid alkyl esters are also suitable. Vinyl esters of carboxylic acids having 1 to 20 C atoms are, for example, vinyl laurate, vinyl stearate, vinyl propionate, versatic acid vinyl ester and vinyl acetate. Examples of vinyl aromatic compounds are vinyl toluene, α-methylstyrene and p-methylstyrene, α-butylstyrene, 4-n-butylstyrene, 4-n-decylstyrene and especially styrene. An example of a nitrile is methacrylonitrile. Said vinyl halides are ethylenically unsaturated compounds, preferably vinyl chloride and vinylidene chloride, substituted with chlorine, fluorine or bromine. Examples of vinyl ethers include vinyl methyl ether and vinyl isobutyl ether. Vinyl ethers of alcohols containing 1 to 4 C atoms are preferred. Hydrocarbons having 4 to 8 C atoms and 2 olefinic double bonds include butadiene, isoprene and chloroprene. As further monomers (d), C ₅ -C ₁₀ alkyl acrylates and C ₅ -C ₁₀ alkyl methacrylates and vinyl aromatic compounds, in particular styrene and mixtures thereof, are preferred. Particularly preferred are n-hexyl acrylate, octyl acrylate and 2-ethylhexyl acrylate, 2-propylheptyl acrylate, styrene and mixtures of these monomers. Further monomers (d) are, eg monomers, even in particular C ₁ -C ₁₀ hydroxyalkyl (meth) acrylate and (meth) acrylamide containing hydroxyl groups. Furthermore, further monomers (d) include phenyloxyethyl glycol mono (meth) acrylate, glycidyl acrylate, glycidyl methacrylate, amino (meth) acrylate, such as 2-aminoethyl (meth) acrylate. Further monomers (d) also include crosslinkable monomers.

In an embodiment of the invention the copolymer is
(A) one or more main monomers 79.5-99.5% by weight selected from the group consisting of C1-C4 alkyl (meth) acrylates,
(B) 0.5-5% by weight of one or more acid monomers selected from acrylic acid and methacrylic acid,
(C) 0-20% by mass of acrylonitrile
And no additional monomers, which are different from the monomers (a) to (c).

  The type and amount of monomers of the copolymer are adapted to some extent so that the glass transition temperature of the emulsion polymer is in the range of +10 to + 45 ° C., in particular +15 to + 40 ° C. The glass transition temperature can be measured by differential scanning calorimetry (ASTM D 3418-08, so-called “midpoint temperature”).

The copolymer can be produced by emulsion polymerization, and an emulsion polymer is important. In the case of the emulsion polymerization, ionic emulsifiers and / or nonionic emulsifiers and / or protective colloids are usually used to assist the dispersion of the monomers in an aqueous medium, or as surfactant compounds. Stabilizers are used. Protective colloids are polymeric compounds that bind large amounts of water during solvation and stabilize the water-insoluble polymer dispersion. Unlike emulsifiers, the protective colloid usually does not reduce the interfacial tension between the polymer particles and water. A detailed description of suitable protective colloids can be found in Houben-Weyl, Methoden der organischen Chemie, Volume XIV / 1, Makromolekulare Stoffe, Georg-Thieme-Verlag, Stuttgart, pages 411-1420. Examples of the protective colloid include amphiphilic polymers, that is, polymers having hydrophobic groups and hydrophilic groups. Natural polymers, such as starch, or synthetic polymers are important. While the protective colloid has a number average molecular weight of more than 2000 g / mol, for example 2000-100000 g / mol, in particular 5000 to 50000 g / mol, as emulsifiers, their molecular weight is usually less than 2000 g / mol, or in particular 1500 g / mol. This applies to anionic surfactants as well as nonionic surfactants that are less than mol. In particular, anionic and nonionic emulsifiers are used as surfactants. Suitable emulsifiers are, for example, a degree of ethoxylation of from 3 to 50, C ₈ -C ₃₆ fatty alcohols ethoxylated, having degrees of ethoxylation from 3 to 50, ethoxylated mono--C ₄ -C ₁₂ alkylphenols Ethoxylated di-C ₄ -C ₁₂ alkylphenols and ethoxylated tri-C ₄ -C ₁₂ alkylphenols, alkali metal salts of dialkyl esters of sulfosuccinic acid, alkali metal salts of C ₈ -C ₁₂ alkyl sulfates and C ₈ -C ₁₂ alkyl sulfate ammonium salt, C ₁₂ -C ₁₈ alkali metal salts and C ₁₂ -C ₁₈ ammonium salts of alkylsulfonic acids of alkylsulfonic acids and C ₉ -C ₁₈ alkali metal alkyl aryl sulfonate, with salt and C ₉ -C ₁₈ ammonium salts of alkyl aryl sulfonic acids That. When emulsifiers and / or protective colloids are used together as an aid for the dispersion of the monomers, the amount used is for example 0.1-5% by weight, based on the monomers . Trade names for the emulsifiers are, for example, Dowfax® 2 A1, Emulan® NP 50, Dextrol® OC 50, Emulgator 825, Emulgator 825 S, Emulan® OG, Texapon® NSO, Nekanil (R) 904 S, Lumeten (R) I-RA, Lumeten (R) E 3065, Lumeten (R) ISC, Disponil (R) NLS, Disponil LDBS 20, Disponil (R) FES 77, Lutensol AT 18, Steinapol VSL, Emulphor NPS 25. The surfactant is usually used in an amount of 0.1 to 10% by mass with respect to the monomer to be polymerized.

  The emulsion polymerization is usually carried out at 30 to 130 ° C, in particular 50 to 90 ° C. The polymerization medium may consist of water alone or a mixture of water and a liquid that can be mixed with the water, for example methanol. Advantageously, only water is used. The emulsion polymerization may be carried out as a batch process, or may be carried out in the form of a feeding method including a stepped operation mode or a gradient operation mode. A portion of the polymerization batch is pre-charged, heated to the polymerization temperature and polymerized, followed by the remainder of the polymerization batch, usually one or more supply tubes of several spatially separated supply tubes being the monomer. Preference is given to a feed method in which the feed is fed continuously or stepwise through the feed tube containing in a pure or emulsified form.

  In the case of the emulsion polymerization, usual known auxiliaries such as water-soluble initiators and regulators may be used. Water-soluble initiators for the emulsion polymerization are, for example, ammonium and alkali metal salts of peroxodisulfuric acid, such as sodium peroxodisulfate, hydrogen peroxide or organic peroxides, such as t-butyl hydroperoxide. So-called redox initiator systems are also suitable. The redox initiator system consists of at least one mostly inorganic reducing agent and one inorganic or organic oxidizing agent. The oxidizing component is, for example, an initiator for emulsion polymerization already described above. The reducing component is, for example, an alkali metal salt of sulfite, such as sodium sulfite, sodium hydrogen sulfite, an alkali metal salt of disulfite, such as sodium bisulfite, a bisulfite addition compound of an aliphatic aldehyde and a ketone, such as acetone bisulfite, Or a reducing agent such as hydroxymethanesulfinic acid and salts thereof, or ascorbic acid. The redox initiator system may be used in conjunction with a soluble metal compound whose metal component can occur in multiple valence stages. Common redox initiator systems are, for example, ascorbic acid / iron (II) sulfate / sodium peroxodisulfate, t-butyl hydroperoxide / sodium disulfite, t-butyl hydroperoxide / Na-hydroxymethane-sulfinic acid or t- Butyl hydroperoxide / ascorbic acid. The individual components, for example the reducing component, may be a mixture, for example a mixture of sodium salt of hydroxymethanesulfinic acid and sodium disulfite. The compound is usually used in the form of an aqueous solution, where the lower concentration is determined by the amount of water that can be present in the dispersion, and the upper concentration is determined by the solubility of the compound in water. In general, the concentration is from 0.1 to 30% by weight, preferably from 0.5 to 20% by weight, particularly preferably from 1.0 to 10% by weight, based on the solution. The amount of initiator is generally from 0.1 to 10% by weight, preferably from 0.5 to 5% by weight, based on the monomer to be polymerized. A plurality of different initiators can also be used during the emulsion polymerization. In order to remove residual monomers, an initiator is usually added even after termination during the original emulsification.

  In the polymerization, the regulator can be used in an amount of, for example, 0 to 0.8 part by mass with respect to 100 parts by mass of the monomer to be polymerized, and the molecular weight is lowered by the regulator. For example, a compound having a thiol group, such as t-butyl mercaptan, mercaptoethyl propionate, 2-ethylhexyl thioglycolate, thioglycolic acid ethyl ester, mercaptoethanol, mercaptopropyltrimethoxysilane, n-dodecyl mercaptan, or t- Dodecyl mercaptan is suitable. In addition, regulators without thiol groups may be used, for example terpinol. In a preferred embodiment, the emulsion polymer is produced using 0.05 to 0.5% by mass of at least one molecular weight regulator based on the monomer amount.

  The polymer dispersion used for coating the packaging material may consist of an emulsion polymer dispersed alone in water for use according to the present invention. However, the polymer dispersion may contain further additives such as fillers, antiblocking agents, colorants, flow agents or thickeners.

  In an embodiment of the invention, the at least one copolymer is used in combination with up to 1 part by weight of a platelet pigment, relative to 1 part by weight of the copolymer. Examples of platelet pigments are talc, clay or mica. Talc is preferred. A preferred form factor (length to heat ratio) is greater than 10.

The polymer dispersion forms a barrier layer after coating the substrate. In particular, the coating with said copolymer is at 23 ° C. for gaseous n-hexane of less than 50 g / m ² d, in particular less than 10 g / m ² d, particularly preferably less than 5 g / m ² d or less than 1 g / m ² d. A barrier layer is present when a copolymer is used that results in transmission and having a coating weight of 20-25 g / m ² on paper (see measurement method in the examples below).

  The content of at least one copolymer in the dispersion used for coating is in particular at least 1% by weight, in particular at least 5% by weight, and up to 60% by weight, or up to 75% by weight. In particular, the content of at least one copolymer in the aqueous dispersion is 15 to 75% by weight, or 40 to 60% by weight. Preferred aqueous polymer dispersions of said copolymers are 10-150000 mPa.s, or 200-5000 mPa.s at a pH value of 4 and a temperature of 20 ° C. s viscosity (measured with a Brookfield viscometer at 20 ° C., 20 rpm, spindle 4). The average particle size of the copolymer particles dispersed in the aqueous dispersion is, for example, 0.02 to 100 μm, particularly 0.05 to 10 μm. The average particle size can be measured, for example, by optical microscopy, light scattering, or freeze fracture electron microscopy.

  According to the invention, the carrier substrate is coated with at least one aqueous dispersion of the copolymer. Suitable substrates are in particular paper, cardboard and polymer sheets. The dispersion used for the coating can contain further additives or auxiliaries, for example thickeners, wetting auxiliaries or binders for adjusting the rheology.

  The dispersion can be used, for example, by applying the coating composition on a coating machine, on paper, on cardboard, or on a carrier sheet made of plastic. As long as a web-like material is used, the polymer dispersion is usually applied from a trough via an applicator roll and made uniform by an airbrush. Other methods of applying the coating are successful, for example by the reverse gravure method, by the spray coating method or by the roller blade method or by other coating methods known to those skilled in the art. In so doing, the carrier substrate is coated on at least one side, i.e. the carrier substrate may be coated on one or both sides. Preferred coating methods for paper and cardboard are curtain coating, air blade, bar coating or blade coating. Preferred coating methods for sheet coating are blade method, wire blade method (Draftkel), air brush method, reverse rotating roll coating method, reverse rotating gravure coating method, casting head method or nozzle method.

The amount applied to the flat material is 1-10 g per 1 m ² (polymer, solid), in particular 2-7 g / m ² , especially on paper or cardboard, especially 5 ˜30 g / m ² . After applying the coating composition onto the carrier substrate, the solvent or water is evaporated. For this purpose, for example in the case of continuous work, the material can be conducted to a drying passage which can be equipped with an infrared irradiation device. Thereafter, the coated and dried material is guided onto a chill roll and finally wound up. The thickness of the dried coating is in particular at least 1 μm, in particular 1 to 50 μm, particularly preferably 2 to 30 μm or 5 to 30 μm.

  The barrier layer may be present on at least one of the packaging material surfaces. The barrier layer may form at least one of a plurality of layers of a multi-layer packaging covering, or may be present on at least one side of an inner bag that is present in the packaging as a covering. The barrier coating may be applied directly on the surface of the carrier material, but between the carrier and the barrier coating, further layers, such as a primer layer, a further barrier layer or colored or There may be a black and white printing ink layer. The barrier layer is in particular on the inside of the packaging material facing the package.

  The inner bag is made in particular from a polymer sheet. The material of the inner bag is selected in particular from polyolefins, in particular polyethylene or oriented polypropylene, in which case the polyethylene may be produced by a high pressure polymerization process of ethylene as well as a low pressure polymerization process of ethylene. In order to further improve the adhesion on the sheet, the carrier sheet may first be subjected to a corona discharge. Other suitable carrier sheets are, for example, sheets made of polyester, such as polyethylene terephthalate, sheets made of polyamide, polystyrene and polyvinyl chloride. In one embodiment, the carrier material is, for example, a biodegradable sheet comprising a biodegradable aliphatic aromatic copolyester and / or polylactic acid, such as an Ecoflex® sheet or an Ecovio® sheet. . Suitable copolyesters are, for example, alkanediols, in particular C2 to C8 alkanediols, such as 1,4-butanediol, aliphatic dicarboxylic acids, in particular C2 to C8 dicarboxylic acids, such as adipic acid and aromatic dicarboxylic acids, such as terephthalate. Formed from acids.

  The thickness of the carrier sheet is generally in the range of 10 to 200 μm.

  In order to obtain special surface or coating properties of the sheet and packaging material, such as good printability, even better barrier or blocking behavior, good water resistance, the coated substrate is preferably as described above. It is preferred to overcoat with a coating layer that further imparts properties or to subject the barrier coating to a corona discharge treatment. According to the present invention, the precoated substrate exhibits good topcoatability. It can be overcoated again after the above-described method, or can be coated in a continuous process, for example several times using, for example, a curtain coater, without intermediate winding and unwinding of the sheet or paper. Thereby, the barrier layer according to the invention is present inside the system, and the surface properties are further defined by the coating layer. The coating layer has good adhesion to the barrier layer.

  The object of the present invention is a method for producing a packaging material, wherein the composition in the form of the above aqueous polymer dispersion is used, applied to the packaging material substrate or the surface of the inner bag and dried, and the aqueous Also the method, wherein the polymer dispersion contains at least one of the above copolymers.

  The subject of the invention is also an aqueous solution containing at least one of the above-mentioned copolymers for producing a barrier layer for volatile mineral oil components, in particular for producing packaging materials, in particular food packaging materials. The use of a polymer dispersion.

  The substrate coated according to the present invention exhibits an excellent barrier effect on volatile mineral oil components. The coated substrate itself may be used as a packaging material. The coating has very good mechanical properties and exhibits, for example, good block behavior.

Example Unless stated otherwise from the above description, the percentage description always means mass%. Content descriptions are relative to the content in an aqueous solution or dispersion.

The following ingredients were used:
DINP diisononyl phthalate MMA methyl methacrylate MA methyl acrylate AS acrylic acid S styrene nBA n-butyl acrylate AN acrylonitrile Bu butadiene.

Test on fat barrier To test the fat barrier layer, a 10 × 10 cm sized blotter paper sheet is coated with the respective polymer and contacted with a test fat or test oil (eg 2 ml of oil acid). It was. The area of the area where the fat is immersed until after 16 hours at 60 ° C. is evaluated. Depending on the quality, the fat strikethrough is evaluated after x hours.

Barrier test for gaseous mineral oil components (Test Method 1)
The test configuration was packed with the following:
1. Donor: 30 g / m ² paper loaded with Gravex 913 1% (Shell, mineral oil for printing ink),
2. Spacer paper to eliminate contact with moisture, 30 g / m ² ,
3. Barrier material to be tested,
4). Receptor: LLDPE having a commercially available PE sheet of 20 μm and a density of 0.915 g / cm ³ .
The packet (basic dimension 10 × 10 cm) was entirely wrapped with aluminum foil.

  The test system is stored at 60 ° C., and a strip of oil is periodically cut from the receptor sheet, extracted with n-hexane at 2 hours / 25 ° C., and having 15 to 25 carbon atoms. The content of was determined by measuring by on-line HPLC-GC. The leakage time for the mineral oil component to leak from the barrier material was measured. This leakage time is the time when the mineral oil component is detected for the first time after the detection limit is exceeded during extraction.

Barrier test for gaseous mineral oil components (Test Method 2)
9 ml of hexane is fed into a container with a sponge and closed with a lid with an opening and a seal ring (inner diameter 63 mm). The opening is tightly closed with the barrier material to be tested, wherein the barrier material is not in contact with a sponge impregnated with hexane. The mass reduction rate of the container is measured. This mass reduction rate is a measure for the hexane that flows through the barrier material through the gas phase and thus a good barrier effect for the gaseous mineral oil component. The mass loss rate in grams is converted to 1 m ^{2 of} paper area and further described as g / m ² d (1 day).

Example 1:
Comparative testing of barriers to fat barrier / gaseous mineral oil components For the polymers listed in Table 1, the barrier effect on fats and oils, ie on fatty acids and fatty acid esters (fat barrier), and on gaseous mineral oil components, ie volatilization A barrier against volatile hydrocarbons (hereinafter referred to as mineral oil barrier) was tested according to Test 1. The results are summarized in Table 1.

  The results show that no barrier action on the gaseous mineral oil component is inferred from a coating having a fat barrier effect. The tested MMA / MA / AS copolymer actually exhibits a mineral oil barrier, for example when the copolymer is coated on polyethylene. However, it has been found that the polymer is not well coated on paper, presumably due to the high glass transition temperature, and that the coating has a defect location that allows the test oil to penetrate. It was.

Example 2: Preparation of polymer dispersion The reactor after washing with nitrogen is pre-charged with 450.0 g of demineralized water and 3.0 g of emulsifier (Disponil® LDBS 20, 20% in water). The mixture in the charge is heated to 70-90 ° C. Subsequently, 21.43 g (7%) of sodium peroxodisulfate are fed in and stirred for 50 minutes. An emulsified feed consisting of 240.0 g of water, 26.67 g of emulsifier (Dowfax 2A1, 45% in water) and 600.0 g of the monomer mixture listed in Table 2 is metered into the reactor within 2 hours. After the emulsification supply is completed, post-polymerization is performed for 45 minutes. The reactor is then cooled to room temperature.

  Solid content: about 45%.

Example 3 Comparative Test of Barrier to Gaseous Mineral Oil Component Various barrier materials were tested in Test Method 2 for good barrier effect on gaseous mineral oil component. The results are summarized in Table 3.

  The results show that Examples B1-B5, B8 and B9 according to the invention have very good barrier properties for the gaseous mineral oil component.

Claims (15)

A paper or cardboard packaging material, wherein at least a portion of the packaging material is made from recycled paper loaded with mineral oil, and the packaging material is coated with an aqueous polymer dispersion containing at least one copolymer One or more main monomers having at least one barrier layer, wherein the copolymer is selected from the group consisting of (a) C1-C4 alkyl (meth) acrylates,
(B) 0.1-5% by weight of one or more acid monomers,
(C) can be prepared by emulsion polymerization from 0 to 20% by weight of acrylonitrile and from 0 to 10% by weight of further monomers different from (d) monomers (a) to (c), and the glass transition temperature of the copolymer is , In the range of +10 to + 45 ° C., wherein the barrier layer may be present on at least one of the packaging material surfaces, or the barrier layer may be a plurality of layers of a multilayer packaging material coating. Wherein the barrier layer may be present as a coating on at least one side of an inner bag present in the packaging material.   The packaging material according to claim 1, wherein at least 70% by mass of the copolymer is composed of the main monomer (a).   The packaging material according to claim 1 or 2, wherein the main monomer (a) is selected from the group consisting of methyl acrylate, methyl methacrylate, ethyl acrylate and n-butyl acrylate. One or more main monomers of 79.5-99.5% by weight, wherein the copolymer is selected from the group consisting of (a) C1-C4 alkyl (meth) acrylates,
(B) 0.5-5% by weight of one or more acid monomers selected from acrylic acid and methacrylic acid,
(C) 0-20% by mass of acrylonitrile
The packaging material according to any one of claims 1 to 3, characterized in that it contains no further monomers, which can be produced from the monomers (a) to (c).   The packaging material according to any one of claims 1 to 4, wherein a glass transition temperature of the copolymer is in a range of +15 to + 40 ° C.   The packaging material according to claim 1, wherein 1 to 20% by mass of the copolymer can be produced from acrylonitrile.   Further monomers (d) are C5 to C20 alkyl (meth) acrylates, vinyl esters of carboxylic acids containing up to 20 C atoms, vinyl aromatic compounds having up to 20 C atoms, ethylenic different from acrylonitrile Consisting of unsaturated nitriles, vinyl halides, vinyl ethers of alcohols containing 1 to 10 C atoms, aliphatic hydrocarbons having 2 to 8 C atoms and 1 or 2 double bonds, and mixtures of said monomers The packaging material according to any one of claims 1 to 6, wherein the packaging material is selected from a group.   The packaging material according to any one of claims 1 to 7, characterized in that the copolymer is used in combination with up to 1 part by weight of a platelet pigment per 1 part by weight of the copolymer. And having a coating weight of 20-25 g / m ² on the paper permeability and against gaseous n- hexane of less than 50 g / m ² d at coating 23 ° C. in the copolymer, claims 1 to 8 The packaging material according to any one of the preceding items.   10. The copolymer according to claim 1, wherein the copolymer in the aqueous polymer dispersion is contained in an amount of 15 to 75% by weight, preferably 40 to 60% by weight. Packaging material.   The load of mineral oil is derived from printing ink and contains volatile paraffins, volatile naphthenes and / or volatile aromatic hydrocarbons, according to claim 1. The packaging material described.   The barrier layer is present as a coating on at least one side of the inner bag present in the packaging material, and the material of the inner bag is selected from polyolefins, in particular polyethylene or oriented polypropylene The packaging material according to any one of claims 1 to 11.   The packaging material according to any one of claims 1 to 12, wherein the barrier layer has a thickness of 2 to 30 µm.   A method for producing a packaging material according to claim 1, wherein the composition in the form of an aqueous polymer dispersion is used, applied to the packaging material substrate or on the surface of the inner bag and dried, the aqueous polymer dispersion. Wherein said process contains at least one copolymer having the characteristics of any one of claims 1 to 10 in relation to said polymer dispersion.   11. The aqueous polymer dispersion containing at least one copolymer having the characteristics of any one of claims 1 to 10 in relation to the polymer dispersion for producing a barrier layer for volatile mineral oil components Use of liquid.