DE202005006229U1 - Metallized multilayer film - Google Patents

Abstract

Comprising multilayer film
(i) a multilayer film (U) having a film thickness in the range of 5.0 to 50 μm
A transparent sealing layer (S ₁ ) having a layer thickness in the range of 1.0 to 25 μm, based on a thermoplastic polymer and forming one of the two surfaces of the multilayer film; and
- A printed layer (D), which is based on a thermoplastic polymer, wherein the sealing layer (S ₁ ) facing away from the surface of the printed layer (D) has an at least partially metallized region which is at least partially printed;
and
(ii) a transparent multilayer film (W) having a film thickness in the range of 5.0 to 100 μm
- A transparent, gas and / or aroma-dense barrier layer (B);
A carrier layer (T) based on a thermoplastic polymer; and
- If necessary, a sealing layer (S ₂ ), which has a layer thickness in the range of 1.0 to 25 microns, on a thermoplastic polymer ...

Description

The The invention relates to an at least partially metallised multilayer film, which is suitable for packaging perishable foods.

In Food packaging has been increasingly used which under the name "MAP packaging" (modified atmosphere packaging) are known. Such packaging, for example for the packaging of (photo-) oxidation-sensitive foods, used for example by meat, sausages, nuts or chips. By using MAP packaging the shelf life of the food can be prolonged, as it provides a protective gas atmosphere with low Have oxygen content, causing u.a. the (photo) oxidation of certain Fat content of the food is prevented.

A known type of such MAP packaging are tubular bags made of suitable multilayer films are produced.

The However, shelf life of the food can only be ensured if the MAP packaging has adequate gas tightness having. Therefore It is important to find the right gas mixture during the packaging process adjust and the mixing ratio in the package until to maintain the first opening. For packaging that is not completely gas-tight, it can while the storage time to an increased Gas exchange with the environment by diffusion. Often the inert gas atmosphere contains mixtures different gases, often Carbon dioxide and nitrogen, the volume fractions sometimes significantly different from the composition of the ambient air.

Typical inert gas atmospheres consist, for example, of 100% by volume of N ₂ (suitable for packaging of nuts), 70% by volume of CO ₂ + 30% by volume of N ₂ (suitable for packaging of cakes) or 70% by volume of N ₂ + 30 vol.% CO ₂ (suitable for packaging of meat) together. If the protective gas atmospheres additionally contain oxygen, the oxygen content is preferably well below the oxygen content of the ambient air, usually below 1% by volume.

As a result the different composition of the ambient air are some of the Gases endeavor to diffuse out of the package, others on the other hand, to diffuse into the packaging.

A Possibility, to achieve sufficient gas tightness of a packaging material, consists in the use of metallized polymer films, which by known metallization process can be produced. there becomes common a polymer layer is vacuum-coated with a metal, for example with aluminum. The metal is beating settles on the polymer, forming a thin film, which gives the film a high gas tightness. metallized However, packaging materials have the property that they are not are transparent, allowing a visual inspection of the packaged goods not possible through them is.

A adequate gas tightness can also be achieved by packaging materials can be achieved, which contain several layers on different Based polymers. Thus, in the prior art multilayer films known which improve the gas tightness barrier layers included on ethylene-vinyl alcohol copolymers (EVOH) or polyvinylidene chloride (PVDC). Such polymers enable the production of a transparent multilayer film, whereby a Visual inspection of the packaged goods is possible. Are these packaging materials heat sealable, so the sealing layers are often multilayered formed, wherein one of the layers on one or more of the above based polymers. heat sealability and barrier effect in this way simultaneously by the Sealing position guaranteed.

Next the discoloration can also negatively affect the shelf life of the packaged product due to UV radiation become. For example, fats, especially those that tend unsaturated fatty acids contained, for (photo) oxidation and thus deterioration in quality of the packaged food. This reaction is caused by UV radiation favors, so that in particular foods high in fat or foods with heterogeneous structure, which have areas with high fat content, if possible protected against UV radiation should be.

There are known in the prior art films which are metallized only on a part of their surface, wherein the metallized areas are opaque and the other areas are transparent. In this context, for example, reference can be made to US 3,647,508 and WO 2004/009872. Disadvantageous However, these films of the prior art is that in the non-metallized areas, a sufficient barrier effect against gases, flavors and / or UV radiation is achieved because the metal layer unfolds their barrier effect only in the metallized areas.

Of the Invention is based on the object, packaging materials ready to ask what advantages over the packaging materials of the prior art. The packaging materials should have sufficient gas and / or aroma resistance. Further On the one hand, they should allow control of the packaged goods, on the other hand, however, also for the packaging of photosensitive packaged goods should be suitable. Especially should for particularly light-sensitive areas of the packaged goods are more effective Protection against UV radiation guaranteed without completely increasing the visibility of the packaged goods prevent. The individual layers or layers of the multilayer film should also have sufficient bond strength.

• (i) eine mehrlagige Schicht (U), welche eine Schichtdicke im Bereich von 5,0 bis 50 μm aufweist, umfassend – eine transparente Siegellage (S₁), welche eine Schichtdicke im Bereich von 1,0 bis 25 μm aufweist, auf einem thermoplastischen Polymer basiert und die eine der beiden Oberflächen der Mehrschichtfolie bildet; und – eine bedruckte Lage (D), welche auf einem thermoplastischen Polymer basiert, wobei die der Siegellage (S₁) abgewandte Oberfläche der bedruckten Lage (D) einen zumindest teilweise metallisierten Bereich aufweist, welcher zumindest zum Teil bedruckt ist; und
• (ii) eine transparente, mehrlagige Schicht (W), welche eine Schichtdicke im Bereich von 5,0 bis 100 μm aufweist, umfassend – eine transparente, gas- und/oder aromadichte Barrierelage (B); – eine Trägerlage (T), welche auf einem thermoplastischen Polymer basiert; und – ggf. eine Siegellage (S₂), welche eine Schichtdicke im Bereich von 1,0 bis 25 μm aufweist, auf einem thermoplastischen Polymer basiert und die andere der beiden Oberflächen der Mehrschichtfolie bildet.

This object is achieved according to the invention by a multilayer film comprising

• (i) a multilayer film (U) having a film thickness in the range of 5.0 to 50 μm, comprising - a transparent sealing film (S ₁ ) having a film thickness in the range of 1.0 to 25 μm on one thermoplastic polymer based and which forms one of the two surfaces of the multilayer film; and a printed layer (D) which is based on a thermoplastic polymer, wherein the surface of the printed layer (D) remote from the sealing layer (S ₁ ) has an at least partially metallised region which is at least partially printed; and
• (ii) a transparent, multi-layered layer (W) having a layer thickness in the range of 5.0 to 100 μm, comprising - a transparent, gas and / or aroma-dense barrier layer (B); A carrier layer (T) based on a thermoplastic polymer; and - if necessary, a sealing layer (S ₂ ), which has a layer thickness in the range of 1.0 to 25 microns, based on a thermoplastic polymer and forms the other of the two surfaces of the multilayer film.

By the barrier layer (B) of the multilayer film according to the invention is achieved, that the barrier effect against gases and / or flavors and sometimes also against UV rays also guaranteed in those areas of the multilayer film which are not metallized.

The inventive multilayer film characterized by an excellent barrier effect against gases, Aromas and possibly UV radiation, without losing the visibility of the Packing goods thoroughly to prevent. The multilayer film according to the invention offers for the packaged good protection against UV radiation, in particular in the areas which are metallized. Depending on the chemical composition The polymers in the non-metallized areas can also these to some extent UV radiation absorb and thus protect the packaged goods.

The individual layers or layers of the multilayer film also have an excellent composite adhesion. In addition, show suitable Printing inks used to print the metallised areas, because of the metallized substrate a metallic sheen, what for the external appearance the multilayer film is advantageous.

By the internal structure of the multilayer film according to the invention is this economical and can be produced by comparatively few process steps. The small number of layers of the multilayer film brings advantages which, for example, in the production of tubular bag packaging to be expressed. Thus, the plants in the production of such Packaging usually operated at a relatively high speed, and the multilayer films of the invention are easy to process even under these conditions.

The layer thickness of the multi-layered layer (U) including the printed layer (D) and the sealing layer (S ₁ ) is in the range of 5.0 to 50 μm, preferably 6.0 to 45 μm, more preferably 7.0 to 40 More preferably, 8.0 to 35 microns, most preferably 10 to 30 microns and more preferably 12 to 25 microns.

The layer thickness of the multilayered layer (W), which includes the barrier layer (B), the carrier layer (T) and the optionally present sealing layer (S ₂ ), is in the range from 5.0 to 100 μm, preferably 10 to 50 μm, more preferably 12 to 45 microns, more preferably 14 to 35 microns, most preferably 16 to 30 microns and in particular 18 to 25 microns.

In a preferred embodiment the multilayer film according to the invention is on the printed layer (D) both the printed metallized Area as well as the possibly present unprinted metallized area coated with protective varnish.

The sealing layer (S ₁ ) forms a surface of the multilayer film according to the invention. If the multilayer film also has a sealing layer (S ₂ ) in addition to the sealing layer (S ₁ ), then the latter preferably forms the other surface. If, on the other hand, there is no sealing layer (S ₂ ), preferably the carrier layer (T) forms the other surface of the multilayer film according to the invention.

Prefers is the barrier layer (B) between the carrier layer (T) and the printed Position (D) arranged.

In a preferred embodiment has the multilayer film according to the invention a total layer thickness of 10 to 300 μm, more preferably 10 to 100 μm, more preferably 10 to 50 μm and most preferably 20 to 30 microns on.

The carrier layer (T), the barrier layer (B), the sealing layer (S ₁ ) and the possibly present sealing layer (S ₂ ) of the multilayer film according to the invention are transparent. Preferably, the printed layer (D) at the areas which are not metallized, transparent.

The term "transparent" in the sense of the invention means that a packaged product can be viewed through the multilayer film with the naked eye. If at least one of the layers or layers of the multilayer film is not transparent, for example the printed layer (D) in the metallized regions, then the carrier layer (T), the barrier layer (B), the sealing layer (S ₁ ) or the optionally existing sealing layer (S ₂ ) then "transparent" when the non-transparent areas of the printed layer (D) through the carrier layer (T), the barrier layer (B), the sealing layer (S ₁ ) or the possibly existing sealing layer (S ₂ ) can be viewed through the naked eye.

The Transparency is preferably quantified with the aid of densitometers. Such methods are familiar to the person skilled in the art. Preferred may be used as a measure of transparency the cloudiness measured as optical value. The measurement of the turbidity takes place preferably according to the ASTM test standard D 1003-61 m, Procedure A, after calibration of the measuring instrument with turbidity standards between 0.3 and 34% haze. As a measuring instrument, for example, a Hazemeter is the Fa. Byk-Gardner with integrating sphere, which in a solid angle of 8 ° to 160 ° integrated Measurement of diffuse light transmission allowed. The multilayer film according to the invention preferably in the areas where the printed layer (D) is not metallized, one according to the method described above certain cloudiness less than 20%, more preferably less than 18%, even more preferably less than 15%, most preferably less than 10% and in particular less than 8%.

In a preferred embodiment the multilayer film according to the invention is between the barrier layer (B) of the multilayered layer (W) and the printed layer (D) of the multilayered layer (U) a transparent Connecting layer (V) arranged on a thermoplastic Polymer or a laminating adhesive based.

• – (T)/(B)//(D)/(S₁);
• – (T)/(B)//(V)//(D)/(S₁);
• – (S₂)/(T)/(B)//(D)/(S₁); und
• – (S₂)/(T)/(B)//(V)//(D)/(S₁).

The multi-layer film 2 or 3 according to the invention may particularly preferably comprise multilayer layers, the layer sequences (U) // (W) and (U) // (V) // (W) being preferred. Preferred layer sequences within these layer sequences are:

• - (T) / (B) // (D) / (S ₁ );
• - (T) / (B) // (V) // (D) / (S ₁ );
• - (S ₂ ) / (T) / (B) // (D) / (S ₁ ); and
• - (S ₂ ) / (T) / (B) // (V) // (D) / (S ₁ ).

there marks "//" two on each other following layers and "/" two consecutive Documents. It is not mandatory that two layers separated by "//" or two separated by "/" layers follow one another directly, i. touching each other - it is also possible, that further layers or layers are inserted.

The multilayer film according to the invention has on its surface at least the sealing layer (S ₁ ), optionally the sealing layer (S ₂ ) can form the other surface. The sealing layer (S ₁ ) is part of the multilayered layer (U) and the possibly existing sealing layer (S ₂ ) is part of the multilayer sealing layer (W) of the inventions The multilayer film according to the invention.

Preferably, the sealing layer (S ₁ ) and the optionally present sealing layer (S ₂ ) of the multilayer film of the invention are identical or different on a polyolefin, olefin copolymer, polyester, copolyester or mixture thereof, preferably on at least one polymer selected from the group comprising polyolefins , Olefin copolymers and their mixture. The polymers used for the production of the sealing layer (S ₁ ) or (S ₂ ) are approved for the production of layers, which come into contact with food. In a preferred embodiment, the sealing layer (S ₁ ) or (S ₂ ) is the same or different on at least one polyolefin selected from the group consisting of m-polyethylene (m-PE), high density polyethylene (HDPE), low density polyethylene (LDPE ), low density (LLDPE), acrylic acid copolymer, linear polyethylene, especially ionomer (preferably Surlyn ^®, for example, at least partially as a zinc salt), polypropylene (PP), propylene copolymer and a mixture thereof.

In a preferred embodiment of the multilayer film according to the invention, the outer surface of the sealing layer (S ₁ ) and / or the outer surface of the optionally present sealing layer (S ₂ ) is equipped with antifogging properties. This is inventively preferably achieved in that the sealing layer contains an additive with anti-fog properties. Such additives are known to the person skilled in the art. In this regard, for example, on US 5,766,772 to get expelled.

Prefers is the additive with antifogging properties selected from the group consisting from fatty alcohols, polyoxyethylene and polyoxypropylene fatty acid esters, Polyoxyethylene and polyoxypropylene fatty alcohol ethers, fatty acid esters polyhydric alcohols or their mixture. Representatives of the above mentioned substance classes are known in the art. In this context For example, see H.P. Fiedler, Lexicon of excipients for pharmacy, Cosmetics and adjacent areas, Editio Cantor Aulendorff, 2002 to get expelled.

In a preferred embodiment it is the additive with anti-fog properties to a substance which at 25 ° C solid or waxy. Particularly preferred are substances which at 25 ° C are waxy and have a softening point in the range of 25 to 80 ° C, more preferably 27 to 70 ° C, more preferably 30 to 60 ° C, most preferably 33 to 50 ° C and in particular 35 to 40 ° C exhibit.

These the additive with antifogging properties is a fatty acid ester a polyhydric alcohol, the ester is preferably derived from a polyhydric alcohol having preferably 2 to 8 carbon atoms, in particular 3 to 6 carbon atoms. Preferably, the polyvalent contains Alcohol 2 to 8 hydroxyl groups, in particular 3 to 6 hydroxyl groups. examples for such polyhydric alcohols are glycerol, threitol, erythritol, xylitol, Sorbitol and mannitol. The number of esterified hydroxyl groups of polyhydric alcohol may vary, at least one is preferred Hydroxyl group not esterified; when four or more hydroxyl groups are present, are preferably at least two, more preferred at least three hydroxyl groups are not esterified.

• – gesättigten Carbonsäuren, wie z.B. Caprylsäure, Caprinsäure, Laurinsäure, Myristinsäure, Palmitinsäure, Stearinsäure, Arachinsäure, Behensäure und Lignocerinsäure;
• – einfach ungesättigten Carbonsäuren, wie z.B. Palmitölsäure, Ölsäure, Elaidinsäure, cis-Vaccensäure, Erucasäure und Nervonsäure;
• – mehrfach ungesättigten Carbonsäuren, wie z.B. Linolsäure, α-Linolensäure, γ-Linolensäure, Di-homo-γ-Linolensäure und Arachidonsäure;
• – ungesättigten Hydroxycarbonsäuren, wie z.B. Ricinolsäure; und
• – gesättigten Hydroxycarbonsäuren, wie z.B. Hydroxystearinsäure, insbesondere 12-Hydroxy-Stearinsäure.

"Fatty acids" in the sense of the description are linear or branched monocarboxylic acids having 8 to 32 carbon atoms, preferably 12 to 24 carbon atoms, in particular 14, 16 or 18 carbon atoms, which are 1, 2, 3, 4 or 5 olefinic, conjugated or non-conjugated May have double bonds which may independently have cis or trans configuration. Further, the carbon atoms may be substituted with 1, 2 or 3 hydroxyl groups. Preferably, the fatty acids are selected from the group consisting of

• Saturated carboxylic acids such as caprylic acid, capric acid, lauric acid, myristic acid, palmitic acid, stearic acid, arachic acid, behenic acid and lignoceric acid;
• Monounsaturated carboxylic acids, such as palmitoleic, oleic, elaidic, cis-vaccenic, erucic and nervonic acids;
• Polyunsaturated carboxylic acids, such as linoleic acid, α-linolenic acid, γ-linolenic acid, di-homo-γ-linolenic acid and arachidonic acid;
• - unsaturated hydroxycarboxylic acids, such as ricinoleic acid; and
• - saturated hydroxycarboxylic acids, such as hydroxystearic acid, in particular 12-hydroxy-stearic acid.

"Fatty alcohols" in the sense of the description are derived from the above-defined fatty acids in that the carboxylic acid group was reduced to a hydroxymethyl group.

• – auf einem thermoplastischen Polymer; oder
• – auf einem anorganischen Oxid.

The multilayer film (W) of the multilayer film according to the invention has a transparent, gas and / or aroma-tight barrier layer (B), which preferably adjoins the carrier layer (T) on one side. In a preferred embodiment, the barrier layer (B) is based

• On a thermoplastic polymer; or
• - on an inorganic oxide.

The barrier layer (B) is gas and / or aroma-tight. The person skilled in suitable methods for measuring the oxygen or aroma resistance are known. The gas-tightness of the multilayer film according to the invention, determined according to DIN 53380, is preferably less than 5.0, more preferably less than 4.0 and in particular less than 2.0 [cm ³ / m ² dbar O ₂ ].

In a preferred embodiment the barrier layer (B) is based on at least one polymer selected from the group comprising ethylene-vinyl alcohol copolymer (EVOH), polyvinylidene chloride (PVDC), Polyvinyl alcohol (PVOH) and vinylidene chloride copolymer.

In another preferred embodiment, the barrier layer (B) is based on an inorganic oxide, preferably on AlO _x or SiO _x . The layer can be applied for example by chemical vapor deposition (CVD) or physical vapor deposition (PVD). Such methods are known to the person skilled in the art. For example, it is possible to evaporate aluminum in vacuo and to deposit AlO _x by metering a certain amount of oxygen. In the case of silicon, the evaporation can take place with the aid of an electron beam.

The barrier layer (B) thus applied is preferably less than 1 .mu.m thick, more preferably has a layer thickness in the range of 0.01 and 0.1 .mu.m. For further details, for example, in full US 5,728,224 to get expelled.

The Barrier location (B) should be both for Oxygen as well Water vapor to be largely impermeable. The barrier layer (B) of the multilayer film according to the invention may be preferred additionally also assume a UV barrier function to the gas barrier function, i. the barrier situation (B) preferably indicates Light waves in the visible spectrum (400 to 800 nm) sufficient Transparency, for Light waves in the UV spectrum (<400 nm), on the other hand, has a barrier effect.

In a preferred embodiment the multilayer film according to the invention the carrier layer is based (T) and / or the printed layer (D) and / or the possibly existing Bonding layer (V) the same or different on a thermoplastic Polymer selected from the group consisting of polyolefin, olefin copolymer, polyester, Copolyester, polyamide and copolyamide, or a mixture thereof.

Preferably, the carrier layer (T) of the multi-ply layer (W) of the multilayer film of the invention is based on at least one thermoplastic polymer selected from the group consisting of polyamides (PA), copolyamides (CoPA), polyolefins (PO), olefin copolymers (CoPO), polystyrene (PS), polyesters (P), copolyesters (CoP), polyvinyl chloride (PVC) and mixtures thereof, in particular on at least one polyolefin, olefin copolymer, polyester or copolyester. The carrier layer (T) is preferably based on a thermoplastic polymer which has a melting temperature of more than 100 ° C. In a preferred embodiment, the carrier layer (T) is based on a polyester or copolyester selected from the group consisting of polyethylene terephthalate (PET, amorphous or crystalline), polybutylene terephthalate (PBT), polycaprolactone (PCL), polybutylene adipate (PBA) and mixtures thereof. In another preferred embodiment, the carrier layer (T) is based on a polyolefin or olefin copolymer selected from the group consisting of polyethylene (PE), for example polyethylene with a density of at most 0.92 g / cm ³ , polypropylene (PP), Ethylene copolymer, in particular ethylene-vinyl acetate copolymer, and / or propylene copolymer. The carrier layer (T) is particularly preferably based on polypropylene, propylene copolymer or a mixture thereof. Biaxially oriented polypropylene (BOPP) is particularly preferred.

Prefers has the multilayer film according to the invention between the barrier layer (B) and the printed layer (D) a tie layer (V) on.

In a preferred embodiment, this bonding layer (V) is based on a polyolefin, olefin copolymer or mixture thereof. The bonding layer (V) is preferably based on a thermoplastic polymer having a melting temperature of more than 100 ° C. Particularly preferably, the bonding layer (V) is based on polyethylene, in particular polyethylene with a density of at most 0.92 g / cm ³ , polypropylene (PP), ethylene copolymer, in particular ethylene-vinyl acetate copolymer and / or propylene copolymer. More preferably, the tie layer (V) is based on polypropylene, propylene-co polymer or mixture thereof.

In another preferred embodiment this bonding layer (V) is based on a laminating adhesive, preferably on a one- or two-component polyurethane laminating adhesive.

The Layer thickness of the possibly present connection layer (V) is preferably in the range of 1.0 to 25 μm, preferably 5.0 to 10 microns.

Preferably, the printed layer (D) of the multilayer film (U) of the multilayer film of the invention is based on at least one thermoplastic polymer selected from the group consisting of polyamides (PA), copolyamides (CoPA), polyolefins (PO), olefin copolymers (CoPO), Polystyrene (PS), polyesters (P), copolyesters (CoP), polyvinyl chloride (PVC), or mixtures thereof, in particular on at least one polyolefin, olefin copolymer, polyester or copolyester. The printed layer (D) is preferably based on a thermoplastic polymer which has a melting temperature of more than 100 ° C. In a preferred embodiment, the printed layer (D) is based on a polyester or copolyester selected from the group consisting of polyethylene terephthalate (PET, amorphous or crystalline), polybutylene terephthalate (PBT), polycaprolactone (PCL), polybutylene adipate (PBA) and mixtures thereof. In another preferred embodiment, the printed layer (D) is based on a polyolefin or olefin copolymer selected from the group consisting of polyethylene (PE), for example polyethylene with a density of at most 0.92 g / cm ³ , polypropylene (PP) , Ethylene copolymer, in particular ethylene-vinyl acetate copolymer, and / or propylene copolymer. The printed layer (D) is particularly preferably based on polypropylene, propylene copolymer or a mixture thereof. Biaxially oriented polypropylene (BOPP) is particularly preferred.

In a preferred embodiment the multilayer film according to the invention is the carrier layer (T) and / or the printed layer (D) the same or different mono- or biaxially oriented. Biaxially oriented polypropylene (BOPP) is particularly preferred. A monoaxial orientation is preferably in the machine direction, a biaxial orientation preferably additionally in the transverse direction.

According to the invention at least the surface of the barrier facing the barrier layer (B) printed layer (D) an at least partially metallized area on. On the one hand, the metallization causes protection against radiation, especially against UV radiation, on the other hand, it improves the gas barrier properties of the multilayer film. Because the metal applied to the printed layer (D) in only a relatively small thickness These benefits will be without significant weight gain Multilayer film achieved.

Of the metallized area can be a single coherent Range, which has a percentage of the surface of printed layer (D) covered. However, it is also possible that the printed layer (D) on several of its surfaces separated several more having metallized areas which are not interconnected are.

In a preferred embodiment has only the barrier layer (B) facing surface of the printed Position (D) one or more metallized areas on, so that the other surface is free of metallized areas.

to Metallization are different metals or mixtures thereof suitable. According to the invention preferred is the printed layer (D) metallized with aluminum or copper, with aluminum being particularly preferred.

in the Ways of metallization is only a comparatively thin metal film applied to the printed layer (D) whose thickness is preferred in Range of 5 to 100 nm, more preferably 10 to 50 nm. Such metal films can For example, be applied by plasma coating.

Prefers are 1.0 to 100% of the surface area the printed layer (D) metallized, more preferably 25 to 100%, more preferably 30 to 100%, most preferably 35 to 100% and in particular 40 to 100%.

Of the or the metallized region (s) of the surface of the printed layer (D) is (are) at least partially printed. For printing are customary methods, wherein flexographic or gravure printing are preferred. Preferably, the Printing ink selected on one or more polymers the group consisting of polyvinyl chloride (PVC), polyvinyl butyral (PVB), nitrocellulose (NC) and polyurethane (PU).

Prefers are 1.0 to 100% of the area the metallized areas printed, more preferably 25 to 100%, more preferably 50 to 100%, most preferably 75 to 100% and in particular 90 to 100%.

are printed less than 100% of the metallized area, so can be a printed metallized area of an unprinted metallized Range differ.

According to the invention is both the printed as well as the possibly unprinted metallized area preferably coated with protective lacquer. As a protective lacquer compositions are suitable which have sufficient resistance against the attack of acids and lyes. Particularly preferred is an etch-resistant transparent Protective lacquer, preferably based on polyvinyl chloride, in particular as a one-component system. The protective lacquer usually contains in the liquid state food-grade, volatile, organic solvent, preferably selected from the group consisting of ethyl acetate, n-butyl acetate, methyl acetate, n-amyl acetate, methyl isobutyl ketone, methyl ethyl ketone, ethanol, propanol, Isopropanol, n-butanol, toluene, heptane, isopropyl acetate and hexane. After applying the protective varnish, the solvent is removed, whereby the protective lacquer is etch-resistant Protection especially against Alkalis, but also opposite acids gives.

ever according to the chemical composition of the printing ink (s) used it also possible that this already has a sufficient etch resistance, so that the separate coating with a protective varnish in this case is not required. is intends that in the multi-layer film in addition to printed and transparent surfaces also a metallic surface from the outside is visible, however, it is etch-resistant even when used Inks the additional Use of a transparent protective varnish is indicated.

On this manner can be used in the production of the multilayer film according to the invention by treating the metallized, printed and possibly additionally with Protective paint coated printed layer (D) with a suitable acid or alkali bath the metal Partially be replaced by those areas that are not with Protective varnish or etching-resistant Ink coated are (demetallization). The result is a printed layer (D), which has non-metallized and metallized regions, the metallized areas being coated with protective varnish and at least partially printed under the protective varnish. is the polymer on which the printed layer (D) is based is transparent, so arise in the areas where the metal by the etching process is removed again, transparent areas.

• – ein Teil der Oberfläche der bedruckten Lage (D) ist metallisiert, wobei die gesamte metallisierte Fläche bedruckt und ggf. mit Schutzlack überzogen ist. In diesem Fall weist die bedruckte Lage (D) einen oder mehrere bedruckte, metallisierte und ggf. mit Schutzlack überzogene Bereiche und einen oder mehrere nicht metallisierte Bereiche auf, wobei der oder die nicht metallisierten Bereiche weder bedruckt, noch mit Schutzlack überzogen sind;
• – ein Teil der Oberfläche der bedruckten Lage (D) ist metallisiert, wobei ein Teil der metallisierten Fläche bedruckt ist und sowohl der bedruckte metallisierte Bereich als auch der unbedruckte metallisierte Bereich mit Schutzlack überzogen ist. In diesem Fall weist die bedruckte Lage (D) einen oder mehrere bedruckte, metallisierte und mit Schutzlack überzogene Bereiche, einen oder mehrere unbedruckte, metallisierte und mit Schutzlack überzogene Bereiche und einen oder mehrere nicht metallisierte Bereiche auf, wobei der oder die nicht metallisierten Bereiche weder bedruckt, noch mit Schutzlack überzogen sind; diese Ausführungsform ist erfindungsgemäß besonders bevorzugt und in 1 und 2 näher erläutert.

The surface of the printed layer (D) has one or more metallized areas. Depending on the metallization and printing, the following preferred embodiments of the multilayer film according to the invention can be distinguished:

• - Part of the surface of the printed layer (D) is metallized, wherein the entire metallized surface is printed and optionally coated with protective lacquer. In this case, the printed layer (D) has one or more printed, metallized and possibly coated with protective coating areas and one or more non-metallized areas, wherein the one or more non-metallized areas are neither printed nor coated with protective lacquer;
• - A part of the surface of the printed layer (D) is metallized, wherein a part of the metallized surface is printed and both the printed metallized area and the unprinted metallized area is coated with protective lacquer. In this case, the printed layer (D) comprises one or more printed, metallized and resist-coated areas, one or more unprinted, metallized and resist-coated areas, and one or more non-metallized areas, the non-metallized area (s) neither printed, still coated with protective varnish; This embodiment is particularly preferred according to the invention and in 1 and 2 explained in more detail.

1 shows a non-to-scale sectional view of a preferred multilayer film (T) / (B) // (V) // (D) / (S ₁ ). Between the carrier layer (T) and the sealing layer (S ₁ ), the printed layer (D), the connecting layer (V) and the barrier layer (B) are arranged. The surface of the printed layer (D) facing the barrier layer (B) has metallized regions (3). The metallized areas (3) have a printed area (2), wherein the metalized area (3) shown on the left side is completely printed and the metallized area shown on the right side is only partially printed. Between the two metallized areas is a non-metallized area. The printed metallized areas and the unprinted metallized areas are coated with protective lacquer (1). The thickness of the metallized area (3), the printed area (2) and the area coated with protective lacquer (1) is greatly enlarged in comparison to the layer thickness of the carrier, intermediate and sealing layer.

2 shows a schematic representation of the printed layer (D) with non-metallized areas (6) and metallized areas, the latter being printed (4) or unprinted (5).

According to the invention preferred For example, the printed layer (D) is based on a polymer which is used before the Metallization throughout is transparent. In this way, the non-metallized areas the printed layer (D) transparent, the metallized areas the printed layer (D) because of the applied metal film, however Not. If one uses a multilayer film according to the invention, which has both transparent and non-transparent regions, For food packaging, it is possible to use certain areas of the food Food behind the non-transparent, i. behind the metallized Areas of the printed layer (D) from UV radiation better protect, other areas of the food behind the transparent, i.e. to arrange the non-metallized areas and so one Visual inspection accessible close.

Particularly preferred embodiments of the multilayer film according to the invention are summarized in the following table:

The inventive multilayer film may contain more layers. For example, the multilayer film one or more identical or different layers based comprising at least one polymer selected from the group Polyolefins, olefin copolymers, polyesters, polyamides, polystyrene (PS), polyethylene terephthalate or polyvinyl chloride.

In principle, the multilayer film according to the invention can additionally contain customary additives or auxiliary substances independently in one or more layers. To vary the sliding properties of the multilayer film, at least one layer may contain lubricants. The lubricants should preferably be contained in the carrier layer (T) and / or the sealing layer (S ₁ ) and / or the sealing layer (S ₂ ), if present. Further, the multilayer film may contain conventional stabilizers, antioxidants, plasticizers, processing aids, UV absorbers, fillers, anti-flame agents, antistatic agents, etc. Such substances are known to the person skilled in the art.

The Production of the Multilayer Film According to the Invention can be used as part of a blow, flat-film, coating, extrusion, Coextrusion or corresponding coating or laminating method include. Combinations of these methods are possible. such Methods are known in the art. In this context can for example, on A.L. Brody, K.S. Marsh, The Wiley Encyclopedia of Packaging Technology, Wiley-Interscience, 2 edition (1997); W. Soroka, Fumdamentals of Packaging Technology, Institute of Packaging Professionals (1995); J. Nentwig, plastic films, Hanser textbook (2000); and S.E.M. Selke, Understanding Plastics Packaging Technology (Hanser Understanding Books), Hanser Gardner Publications (1997) to get expelled. There are known, customary in the prior art manufacturing plants into consideration. In the case of flat film coextrusion are preferred Plants with rapid cooling, How big Chill rolls, used.

The inventive multilayer film let yourself due to the arrangement of the barrier layer (B) between the carrier layer (T) and the printed layer (D) particularly advantageous, in particular economical produce. In a preferred embodiment, the multilayer Layer (U) and the multilayer layer (W) initially produced independently and then with the help of conventional Method joined together, such as. by adhesive laminating, whereby a composite (U) // (V) // (W) arises.

The printed layer (D) is metallized by conventional methods. Suitable methods for the metallization of plastic films are known in the art. It can be used, for example, on Metallization of Polymers 2, Kluwer Academic / Plenum Publishers, 2002.

For example, the printed layer (D) as a prefabricated polymer film and as part of the multilayer layer (U) are introduced into a vacuum chamber and with the aid of suitable pumps, a vacuum in the range of 10 ^-4 to 10 ^-5 bar generated. The metal, for example aluminum, is then heated to a temperature in the range of 1400 to 1500 ° C so that metal vapors rise in vacuo, through which the polymer film is passed. In this way, a very thin metal layer is deposited on the surface of the polymer film. In this case, preferably the entire one surface of the polymer film is metallized. Temperature, vacuum, geometry of the vacuum chamber and velocity of the polymer film through the metal vapor can be varied, whereby the thickness of the metal film can be adjusted. The thickness of the metal film can be measured both electrically and optically.

The metallized printed layer (D) is then printed. For this purpose, customary printing methods are suitable preferred are flexographic or gravure printing. Preference is not given to the entire, but only part of the metallized surface of the printed layer (D) printed.

After that is possibly a - preferably transparent - protective varnish applied, which in the dried state a certain resistance across from having alkaline media. The protective lacquer will be on all those Areas of the surface applied to the printed layer (D), the metallized and possibly printed should stay. Areas of which the metal film and possibly the Printing should be removed again or where the metal by a chemical reaction in a transparent metal compound are not coated with protective varnish. The application of the protective coating is preferably also carried out by a the above-mentioned printing method. Alternatively, as above already mentioned, a printing ink can be used, which in turn has a sufficient etch resistance having.

To the drying of the protective coating is the metallized, printed and coated polymer film is preferably introduced into an etching bath, which is suitable to dissolve the metal in the unpainted areas, whereby the metallization in these areas is reversed (demetallization). Is the polymer on which the printed layer (D) is based transparent, so arise in the areas where the metal by the etching process is removed again, transparent areas. Suitable etching baths contain, for example 10-30% strength Sodium or potassium hydroxide solution. The etching process is usually finished in a few minutes.

is the etching process completed, the polymer film is removed from the etching bath, rinsed with water and dried.

Next the etching it is also possible the metal layer at the places, which are not covered with protective varnish or an etch-resistant Color are covered by a suitable chemical reaction in one to transform transparent metal compound. Unlike etching is In this case, the metal is not removed, but it remains on the printed layer, however, is due to a chemical reaction converted into a metal compound, for example in a metal oxide, which is transparent at a small thickness.

• – durch Extrusionskaschierung der Verbindungsschicht (V) zwischen die Barrierelage (B) und die bedruckte Lage (D), oder
• – mit Hilfe geeigneter Kaschierklebstoffe.

The printed layer (D) thus obtained within the multilayered layer (U) can then be joined to the multilayered layer (W) comprising the carrier layer (T) and the barrier layer (B), for example

• - By extrusion lamination of the bonding layer (V) between the barrier layer (B) and the printed layer (D), or
• - with the help of suitable laminating adhesives.

The are polymers used for layer construction of the multilayer film commercially available and adequately described in the art. They usually become for producing the multilayer films according to the invention as pellets or granules, if necessary mixed in conventional mixing equipment, and processed by melting, preferably by means of extruders.

The inventive multilayer film is ideal for packaging goods, preferably food, especially preferred from perishable foods. The multilayer film can doing so for both hot filling as well as for the heating of contents be used in the multi-layer film to sterilization. The multilayer film is suitable for food packaging like meat, fish, vegetables, Fruits, chips, nuts, Dairy products, smoked Prepared meals, cereals, cereals, bread and pastries, but also from other goods, such as. medical products.

One Another object of the invention relates to the use of a multilayer film described above for producing a Packaging, preferably for perishable food, for example for chips or nuts.

One Another object of the invention relates to a package comprising the multilayer film according to the invention, preferably for Foods, especially preferred for perishable foods.

The inventive packaging can be configured differently. In a preferred embodiment the packaging according to the invention is a tubular bag.

The The following example is for closer explanation of the invention, but should not be limited in scope be interpreted:

Example:

Coextrusion was used to produce a first composite with a layer thickness of 20 μm, which comprised a sealable outer layer and a core layer based on biaxially oriented homopolypropylene. The outer surface of the core layer was coated with SiO _x , wherein the thickness of the SiO _{x was} about 50 nm.

After that coextrusion turned into a second composite with a layer thickness of 20 μm which has a sealable outer layer and a core layer on biaxially oriented homopolypropylene. The outer surface of the Core layer was vapor-deposited with metallic aluminum, the thickness of the Al was about 40 nm. The aluminum layer was partially printed and in certain areas coated with protective varnish. Then took place the demetallization of the aluminum layer in the non-coated with protective paint Areas by lye.

Both So obtained composites were using a two-component polyurethane laminating adhesive connected in such a way that the two sealable outer layers the surfaces the multilayer film formed.

Claims (13)

Multilayer film comprising (i) a multilayer film (U) having a film thickness in the range of 5.0 to 50 μm, comprising - a transparent sealant layer (S ₁ ) having a film thickness in the range of 1.0 to 25 μm, based on a thermoplastic polymer and which forms one of the two surfaces of the multilayer film; and a printed layer (D) which is based on a thermoplastic polymer, wherein the surface of the printed layer (D) remote from the sealing layer (S ₁ ) has an at least partially metallised region which is at least partially printed; and (ii) a transparent, multi-layered layer (W) having a layer thickness in the range of 5.0 to 100 μm, comprising - a transparent, gas and / or aroma-dense barrier layer (B); A carrier layer (T) based on a thermoplastic polymer; and - if necessary, a sealing layer (S ₂ ), which has a layer thickness in the range of 1.0 to 25 microns, based on a thermoplastic polymer and forms the other of the two surfaces of the multilayer film. Multilayer film according to claim 1, characterized in that that on the printed layer (D) both the printed metallized Area as well as the possibly present unprinted metallized area coated with protective varnish is. Multilayer film according to claim 1 or 2, characterized characterized in that the barrier layer (B) between the carrier layer (T) and the printed layer (D) is arranged. Multilayer film according to one of the preceding claims, characterized characterized in that between the barrier layer (B) and the printed Position (D) a transparent connection layer (V) is arranged, which on a thermoplastic polymer or a laminating adhesive based. Multilayer film according to one of the preceding claims, characterized in that the sealing layer (S ₁ ) and the optionally present sealing layer (S ₂ ), identically or differently, have a layer thickness in the region of 1.0 have up to 10 microns. Multilayer film according to Claim 5, characterized in that the sealing layer (S ₁ ) and the optionally present sealing layer (S ₂ ) have, identically or differently, a layer thickness in the range from 1.0 to 5.0 μm. Multilayer film according to one of the preceding claims, characterized in that the sealing layer (S ₁ ) and / or the optionally present sealing layer (S ₂ ) is equipped with antifogging properties. Multilayer film according to one of the preceding claims, characterized characterized in that the barrier layer (B) is based - on one Polymer selected from the group consisting of polyvinylidene chloride, polyvinyl alcohol and ethylene-vinyl alcohol copolymer; or - on one inorganic oxide. Multilayer film according to claim 8, characterized in that the inorganic oxide is SiO _x or AlO _x . Multilayer film according to one of the preceding claims, characterized characterized in that the carrier layer (T) and / or the printed layer (D) the same or different a thermoplastic polymer selected from the group consisting made of polyolefin, olefin copolymer, polyester, copolyester, polyamide and copolyamide, or their mixture. Multilayer film according to one of the preceding claims, characterized in that the polymer on which the carrier layer (T) and / or the printed Position (D) based, the same or different mono- or biaxially oriented is. Packaging comprising a multi-layer film after one of the claims 1 to 11. Packaging according to claim 12, characterized that she is a tubular bag.