EP2978597A1

EP2978597A1 - Flat bags consisting of a multi-ply plastic film

Info

Publication number: EP2978597A1
Application number: EP14714164.2A
Authority: EP
Inventors: Thomas Blum; Matthias JOHANNSEN
Original assignee: Maria Soell High Technology Films GmbH
Current assignee: Maria Soell High Technology Films GmbH
Priority date: 2013-03-27
Filing date: 2014-03-20
Publication date: 2016-02-03
Also published as: WO2014154335A1; DE102013005243A1

Abstract

The invention relates to flat bags consisting of an at least 9-ply, preferably up to 11-ply biaxially oriented plastic film with low water-vapour permeability and low oxygen permeability, a maximum degree of shrinkage of 5% and with a total thickness of between 35 and 80 μm.

Description

Flat bag made of a multilayer plastic film

The present invention relates to flat bags of at least 9, preferably up to 11-layer, biaxially oriented in a stretch of at least 1: 1, 5 oriented plastic film with an oxygen permeability of at most

5 cm ³ / (m ² -24 h ^■ bar) (at 23 ° C and 0% relative humidity) according to DIN 53380-3 and a water vapor permeability of at most 2 g / (m ^{2 ■} 24 h) measured according to DIN EN ISO 15106 -2 (at 23 ° C and 85% relative humidity), a degree of shrinkage of at most 5% at 90 ° C and a total thickness of 35-80 μηη.

As is known to those skilled in the art, flat bags consist of a front wall and a rear wall, which are connected via a peripheral marginal sealing seam to tightly sealed bags. Such bags may, at least in part, consist of extruded, multilayer plastic films and usually a layer of a metal foil, preferably an aluminum foil and / or a ceramic or metal-coated layer as a barrier layer against Wasserwampfbzw. Oxygen permeability and have loss of flavor. Since such barrier layers only in a separate process step with the rest

Layer composite either via adhesive lamination using solvent-based or solvent-free adhesive or by vapor deposition of the ceramic layer, preferably of SiO _x or Al ₂ O ₃ , or the metal layer, preferably from

Aluminum, can be applied to specially coated layers, the manufacturing process of such multilayer, equipped with these barrier layers films, more complicated and time-consuming compared to the

CONFIRMATION COPY Production of multilayer plastic films which can only be produced by extrusion, preferably by coextrusion.

In addition, the recycling of such films with metallic and / or ceramic barrier layers is given only very limited, since these

Materials hardly of the thermoplastic polymers making up the

a large number of layers of such multilayer films is constructed, can be separated.

This is in marked contradiction to efforts to reuse as much as possible raw materials derived from finite petroleum resources, such as polymers from which plastic films are made.

Moreover, it is an effort, not just as complete as possible

Recycling of plastic films, but also for their

Production - in spite of indispensable physical properties, such as a high water vapor, oxygen and / or aroma barrier - as little as possible

Polymeric material, d. H. to use as little as possible of the petroleum resources.

Object of the present invention was therefore, flat bags, especially for the packaging of dry products, preferably multiparticulate, more preferably powdered food products, such as dry soups, instant soups, dry sauces, ground coffee or pharmaceutical powders, exclusively from polymers and therefore to a substantial extent recyclable plastic films with sufficient To provide high barrier properties as possible while reducing the necessary amounts of polymer available. This object is achieved by providing flat bags as a package for dry products, which consists of a at least 9-layer, preferably 11-layer plastic film, with a total thickness of 35-80 pm, a water vapor permeability of at most 2 g / (m ² · 24 h ) measured according to DIN EN ISO 15106-2, an oxygen permeability of <5 cm ³ / (m ^{2 ■} 24 h ^■ bar) (at 23 ° C and 0% relative humidity) and a degree of shrinkage of not more than 5% (at 90 ° C) exist.

The biaxially stretched plastic film used according to the invention preferably has a degree of shrinkage <3%, measured on the basis of DIN EN ISO 11501, after exposure to heat by immersion in a water bath

Application of a dipping time of 10 s at a water temperature of 90 ° C, on.

The biaxially stretched, multilayered plastic film used according to the invention preferably has an at least 9-layered, preferably 11-layered structure

(a) a sealing layer (a) directed towards the filling material made up of

at least one thermoplastic olefin homo- or copolymers, cyclo-olefin copolymers or mixtures thereof;

(b) a primer layer (b),

(f) a layer (f) composed of at least one homo- and / or copolyamide, preferably at least one partially aromatic, amorphous or partially crystalline copolyamide, which is preferably present in the Mixture with at least one further homopolyamide and / or copolyamide is present;

(c) at least one inner barrier layer (c) preferably composed of at least one ethylene-vinyl alcohol copolymer, at least one polyvinyl alcohol, at least one homo- or copolyamide or a mixture of at least two of these polymers;

(g) a layer (g) composed of at least one homo- and / or copolyamide, preferably at least one partially aromatic, amorphous or partially crystalline copolyamide, which is preferably present in admixture with at least one further homopolyamide and / or copolyamide;

(d) a primer layer (d),

(h) a layer (h) of at least one thermoplastic olefin homo- or copolymer, at least one cyclo-olefin copolymer or mixtures thereof, or of at least one homo- or copoylamide or mixtures thereof,

(i) a primer layer (i), and

(E) an outer layer (s) composed of at least one

thermoplastic aliphatic, partially aromatic or aromatic homo- or copolyamide, or at least one thermoplastic, aliphatic, partially aromatic or aromatic homo- and / or copolyester, on.

The multilayered plastic film used according to the invention may have one or two further layers, preferably between the layer (h) and (i) a further layer (h) and / or between the layer (a) and (b) a layer (j).

In such a preferred embodiment, the invention

used, multilayer plastic film

(a) a sealing layer (a) composed of at least one

thermoplastic olefin homo- or copolymers, preferably ethylene homo- or copolymers, more preferably selected from the group consisting of LDPE, LLDPE and mPE and mixtures thereof;

(j) a layer (j) composed of at least one thermoplastic

Olefin homo- or copolymers, cyclo-olefin copolymers or mixtures thereof;

(b) a primer layer (b),

(f) a layer (f) composed of at least one homo- and / or

copolyamide; preferably at least one partially aromatic, amorphous or partially crystalline copolyamide, which is preferably present in admixture with at least one further homopolyamide and / or copolyamide; (C) at least one inner barrier layer (c), preferably composed of at least one ethylene-vinyl alcohol copolymer, at least one polyvinyl alcohol, at least one homo- or copolyamide or a mixture of at least two of these

polymers;

(g) a layer (g) composed of at least one homo- and / or copolyamide; preferably at least one partially aromatic, amorphous or partially crystalline copolyamide, which is preferably present in admixture with at least one further homopolyamide and / or copolyamide;

(d) a primer layer (d);

(h) a layer (h) composed of at least one thermoplastic olefin homo- or copolymer or at least one cyclo-olefin copolymer or mixtures thereof, or of at least one homo- or copolyamide or mixtures thereof;

(h) a second layer (h) composed of at least one

thermoplastic olefin homo- or copolymers or at least one cyclo-olefin copolymer or mixtures thereof or at least one homo- or copolyamide or mixtures thereof;

(i) a primer layer (i); and

(e) an outer layer (e) composed of at least one

thermoplastic aliphatic, partially aromatic or aromatic homo- or copolyamide or at least one thermoplastic, aliphatic, partially aromatic or aromatic homo- and / or copolyester, preferably in the specified sequence on.

The multilayer plastic film used according to the invention is stretched in the longitudinal and / or transverse direction in a drawing ratio of at least 1: 1.5, preferably at least 1: 2, more preferably 1: 2 to 1: 4, since such a multilayer plastic film is characterized by a particularly high Puncture resistance distinguishes.

Despite this biaxial orientation, the biaxially oriented, multilayer plastic film used according to the invention has only a degree of shrinkage of at most 5%, preferably of <3%.

To achieve the above-mentioned low gas permeability, the multilayer plastic film used as packaging material has at least one barrier layer (c), preferably an oxygen and

Water vapor barrier and preferably aroma barrier layer, on.

The barrier layer (c) is preferably composed of at least one ethylene-vinyl alcohol copolymer, at least one polyvinyl alcohol, at least one homo- or copolyamide, or a mixture of at least two of these polymers.

If the barrier layer (c) is made up of at least one ethylene-vinyl alcohol copolymer (EVOH), then this was preferred by in substantial complete hydrolysis of a corresponding ethylene-containing polyvinyl acetate (EVAc). These fully hydrolyzed ethylene-containing polyvinyl acetates have a saponification degree> 98% and an ethylene content of 0.01-80 mol%, preferably 1-50 mol%.

The content of the ethylene component in the ethylene-vinyl alcohol copolymer is preferably at most 50 mol%, more preferably at most 44 mol%, and most preferably 25-44 mol%.

If the barrier layer (c) is made up of at least one polyvinyl alcohol (PVOH), this has preferably been obtained by substantially complete hydrolysis of a polyvinyl acetate (PVAc) and has a saponification degree> 98% as fully saponified polyvinyl acetate.

Preferred homo- or copolyamides for the preparation of the barrier layer (c) are partially aromatic, amorphous or partially crystalline copolyamides, which may optionally be present as a mixture with at least one homopolyamide and / or at least one further copolyamide.

These partially aromatic, amorphous or partially crystalline copolyamides are preferably prepared from aliphatic diamines of 2-10 carbon atoms, especially hexamethylenediamine, and aromatic dicarboxylic acids of 6-14 carbon atoms, e.g. Terephthalic acid or isophthalic acid, and / or from

aromatic diamines having 6-10 carbon atoms, especially p-phenylenediamine or m-xylenediamine, and aliphatic dicarboxylic acids having 6-14 carbon atoms, such as adipic acid. In a particularly preferred embodiment of the plastic film used according to the invention, the barrier layer (c) is composed of at least one ethylene-vinyl alcohol copolymer, at least one amorphous polyvinyl alcohol and / or at least one partially aromatic, amorphous copolyamide or partly aromatic, partially crystalline copolyamide; in particular composed of at least one ethylene-vinyl alcohol copolymer.

In a further preferred embodiment of the invention

Flat bag, the inventively used, multi-layer plastic film further comprises a sealing layer (a), preferably composed of at least one thermoplastic olefin homo- or copolymers, at least one cyclo-olefin copolymers (COC) and / or mixtures thereof.

For the production of the sealing layer (a) of the multilayer plastic film used according to the invention, it is possible to use thermoplastic olefin homopolymers or copolymers of α, β-unsaturated olefins having 2-10 carbon atoms and / or cyclo-olefin copolymers (COC).

In particular, olefin homopolymers, preferably at least one polymer selected from the group comprising ethylene homopolymers (polyethylenes, PE), preferably LDPE and HDPE, are suitable as sealing layer polymers.

Propylene homopolymers (polypropylenes, PP), butylene homopolymers

(Polybutylene, PB) and isobutylene homopolymers (polyisobutylenes, PIB) or mixtures of at least two of said polymers. With "LDPE" is

Denoted low density polyethylene having a density in the range of 0.86- 0.940 g / cm ³ and characterized by a high degree of branching of the molecules. By "MDPE" is meant medium density polyethylene, the density may range between 0.926 and 0.940 g / cm ³ . By "HDPE" is meant high density polyethylene which has little branching of the molecular chain, the density may range between 0.941 and 0.97 g / cm ³ .

Olefin copolymers suitable as sealant polymers are preferably copolymers of ethylene and / or propylene and at least one α-olefin having at least 4, preferably 4-10, more preferably 4-8

Carbon atoms, most preferably copolymers of ethylene and / or propylene with at least one α-olefin selected from the group comprising butene, hexene and octene. This α-olefin content in the olefin copolymer is preferably at most 25% by weight, more preferably at most 15% by weight, each based on the total weight of the olefin copolymer.

As sealant polymers are particularly suitable olefin copolymers

Copolymers of ethylene and at least one α-olefin having at least 4

Carbon atoms such as LLDPE and / or mPE. By "LLDPE" is meant low density linear ethylene copolymers characterized by the presence of a linear backbone having side chains attached thereto and having a density in the range of 0.86 and 0.94 g / cm ³ . By "mPE" is meant ethylene copolymers polymerized by means of metallocene catalysts, preferably having a density in the range of 0.88 and 0.93 g / cm ³ . Olefin copolymers which are particularly suitable as sealing layer polymers are copolymers of propylene and at least one α-olefin with 2 or 4-6, respectively

Carbon atoms, more preferably selected from the group include propylene-ethylene copolymers, propylene-butylene copolymers, propylene-isobutylene copolymers and mixtures of at least two of said copolymers.

Particularly preferred for the production of the sealing layer are (a) ethylene homo- and / or copolymers, most preferably selected from the group consisting of LDPE, LLDPE and mPE and mixtures thereof, and in particular a mixture of at least one ethylene homopolymer low density (LDPE) and at least one linear low density ethylene copolymer

(LLDPE).

To produce the sealing layer (a) of the multilayer film used according to the invention, cycloolefin copolymers (COC) are also suitable, preferably in admixture with a thermoplastic olefin homo- or copolymers of α, β-unsaturated olefins having 2-10 carbon atoms. The term "cyclo-olefin copolymer" or "COC" is understood in the sense of producing a plastic film used according to the invention an amorphous copolymer, which by copolymerization of cyclic (C6-C-i2) olefin monomers, preferably

Norbornene or tetracyclododecene, with a (C ₂ -C ₄ ) olefin, preferably ethylene.

Preferably, as the cycloolefin copolymer, a (C6-C- | ₂₎ -Cycloolefin- _(C2-C4) - olefin copolymer, particularly preferably a norbornene / ethylene copolymer or a tetracyclododecene / ethylene copolymer, most preferably a norbornene / ethylene copolymer used.

The proportion of the structural units derived from at least one cycloolefin in the cycloolefin copolymer is preferably at least 50% by weight, particularly preferably at least 70% by weight, based on the total weight of the cycloolefin copolymer.

Particularly preferred as sealing layer polymers are mixtures of cyclo-olefin copolymers (COC) and thermoplastic olefin homo- or copolymers of α, β-unsaturated olefins having 2-10 carbon atoms, in which the proportion of the cycloolefin copolymer component at most 50 wt .%, Preferably at most 40 wt .-%, and particularly preferably 20-35 wt.% Is.

The multilayer plastic film used according to the invention may comprise one or more further internal layers which are composed of at least one of said thermoplastic olefin homo- or copolymers or cycloolefin copolymers.

In addition to the filling layer directed sealing layer (a) and the inside

Barrier layer (c) with the already mentioned for each of these layers

Composition of the polymer components can according to the invention

used, multilayer plastic film in addition to the adhesion promoter layers (b) and (d) one or more further adhesion promoter layers (i). The adhesion promoter layers (b) and (d) as well as any other existing ones

Adhesive layers (i) may be the same or different.

As adhesion promoters customary adhesion promoter materials can be used.

Preferably, the adhesion promoter layers (b) and (d) and the other existing adhesion promoter layers (i) are the same or different

from one another, from at least one modified thermoplastic polymer, preferably from at least one modified polyolefin homo- or

Copolymers, particularly preferably of at least one modified ethylene homo- or copolymers, which is modified with at least one organic acid or at least one organic acid anhydride, preferably with maleic anhydride.

In a preferred embodiment of the invention used

Multilayer film, the adhesion promoter layers (b) and (d) and preferably the adhesion promoter layer (i) an identical layer structure, preferably an identical layer thickness and / or an identical composition of the polymer component (s) on.

The multilayer plastic film used in accordance with the invention furthermore has two layers (f) and (g), each adjacent to the barrier layer (c) and each independently of one another, composed of at least one homo- and / or copolyamide.

In a preferred embodiment of the invention used

The layers (f) and (g) have an identical multilayer film Layer structure, preferably an identical layer thickness and / or identical polyamide components and / or an identical composition.

For the preparation of the layer (s) as well as the layers (f) and (g) and layer (h) are suitable homo- and / or copolyamides selected from the group of

thermoplastic aliphatic, partially aromatic or aromatic homo- or copolyamides.

These homo- or copolyamides can be prepared from aliphatic diamines with 2-10

Carbon atoms, especially hexamethylenediamine, and / or aromatic diamines having 6-10 carbon atoms, especially p-phenylenediamine, and dicarboxylic acids such as aliphatic or aromatic dicarboxylic acids having 6-14 carbon atoms, e.g. Adipic acid, terephthalic acid or isophthalic acid are produced. Furthermore, homo- or copolyamides of one or more lactams of 4-10 carbon atoms, e.g. ε-caprolactam. Copolyamides may also be prepared from the said aliphatic and / or aromatic diamines, dicarboxylic acids and lactams, e.g. from hexamethylenediamine, adipic acid and ε-caprolactam (PA 6/66). Particularly preferred polyamides are PA 6, PA 12, PA 66, PA 61, PA 6T or corresponding co-polymers of at least two of said structural units, such as

for example, PA 6/66, or mixtures of at least two of said polyamides. The layer (e), the layers (f) and (g) and (h) may be the same or different. In a preferred embodiment of the multilayer film used according to the invention, these layers (e), (f) and (g) and (h) comprise at least one partially aromatic, amorphous or partially crystalline copolyamide, which may be mixed with at least one further homopolyamide and / or at least one other copolyamide can be present. These

partially aromatic, amorphous or partially crystalline copolyamides are preferably selected from aliphatic diamines having 2-10 carbon atoms, in particular

Hexamethylenediamine, and aromatic dicarboxylic acids having 6-14 carbon atoms, e.g. Terephthalic acid or isophthalic acid, and / or from

aromatic diamines having 6-10 carbon atoms, especially p-phenylenediamine or m-xylenediamine, and aliphatic dicarboxylic acids having 6-14 carbon atoms, e.g. Adipic acid, prepared.

Very particularly preferred partially aromatic copolyamides for producing the layers (e), (f) and (g) and (h) are, for example, PA 6I / 6T (from the monomers hexamethylenediamine, terephthalic and isophthalic acid) and MXD6 / MXDI (from the monomers m Xylenediamine, adipic acid and isophthalic acid), which are preferably present in admixture with a further homopolyamide and / or at least one further copolyamide, particularly preferably at least one aliphatic homo- or copolyamide, very particularly preferably PA 6.

The multilayer plastic film used according to the invention may comprise, in addition to the layer (s), (f), (g) and (h), one or more further layers composed of at least one of said homo- and / or copolyamide. The layer (e) as the outer layer of the flat bag according to the invention can also be composed of at least one homo- and / or copolyester selected from the group comprising thermoplastic, aliphatic, partially aromatic or aromatic homo- or copolyesters. Such polyesters are preferably derived from aliphatic polyols such as ethylene glycol or 1, 4-butanediol and

aliphatic and / or aromatic dicarboxylic acids or dicarboxylic acid derivatives such as adipic acid and / or terephthalic acid. Preference is given to using polybutylene adipate (PBA), polyethylene terephthalate (PET), polybutylene terephthalate (PBT) or the corresponding copolyesters. A particularly preferred polyester for the preparation of layer (e) is polyethylene terephthalate (PET).

The multilayer plastic film used according to the invention can furthermore have at least one inner layer (j), preferably adjacent to the sealing layer (a), preferably composed of at least one of the abovementioned thermoplastic olefin homo- or copolymers, cyclo-olefin copolymers or mixtures thereof ,

Preferably, the layer (j) has a polymer composition other than the sealing layer (a), and preferably has a higher softening point than the layer (a).

In a preferred embodiment, the layer (j) is based on at least one ethylene homopolymer or copolymer, particularly preferably on at least one LDPE, mPE and / or LLDPE, in particular on at least one mPE. In a further preferred embodiment, the layer (j) is based on at least one ethylene homo- or copolymers and / or at least one propylene homo- or copolymers, more preferably on at least one propylene copolymer.

The multilayer plastic film used according to the invention may also comprise a further inner layer (h), which preferably has a

Adhesive layer (i) adjacent to the outer layer (s) have.

This layer (h) is preferably from one of said olefin homo- or copolymers, cyclo-olefin homo- or copolymers or mixtures thereof or one of said homo- or copolyamides or mixtures thereof,

preferably composed of an olefin homo-polymer, particularly preferably HDPE, LLDPE, a cyclo-olefin copolymer or mixtures thereof, particularly preferably a mixture of LLDPE and an ethylene / norbornene copolymer.

In a preferred embodiment, the multilayer plastic film used according to the invention has an at least 9-layer, preferably 11-layer, layer structure. In this embodiment, the plastic film preferably has the layers (a), optionally (j), (b), (f), (c), (g), (d), (h), optionally (h), ( i) and (e), preferably in the specified sequence of layers, on.

In these embodiments, the multilayer plastic film, preferably in the specified layer sequences, preferably (A) a sealing layer directed to the filling material (a) composed of at least one thermoplastic olefin homo- or copolymers, cyclo-olefin copolymers, preferably ethylene homo- or copolymers, more preferably selected from the group consisting of LDPE, LLDPE and mPE and mixtures thereof;

(j) optionally a layer (j) composed of at least one thermoplastic olefin homo- or copolymers, preferably of at least one ethylene homo- or copolymers, more preferably of

at least one LDPE, mPE and / or LLDPE, in particular mPE,

(b) at least one primer layer (b),

(f) a layer (f) composed of at least one homo- and / or

copolyamide; preferably of at least one partially aromatic, amorphous or partially crystalline copolyamide, which is preferably present in admixture with at least one further homopolyamide and / or copolyamide;

(c) at least one inner barrier layer (c), preferably

composed of at least one ethylene-vinyl alcohol copolymer, at least one polyvinyl alcohol, at least one homo- or copolyamide or a mixture of at least two of these

Polymers, particularly preferably of at least one ethylene-vinyl alcohol copolymer, as water vapor, oxygen and aroma barrier layer, (g) a layer (g) composed of at least one homo- and / or copolyamide; preferably at least one partially aromatic, amorphous or partially crystalline copolyamide, which is preferably present in admixture with at least one further homopolyamide and / or copolyamide;

(d) a primer layer (d);

(h) at least one layer (h), preferably two layers (h), each composed of at least one thermoplastic olefin homo- or copolymers, a cyclo-olefin copolymer or mixtures thereof or at least one homo- or copolyamide or mixtures thereof , preferably HDPE or a mixture of COC and LLDPE;

(i) at least one primer layer (i); and

(e) an outer layer (e) composed of at least one

thermoplastic aliphatic, partially aromatic or aromatic homo- or copolyamide, or at least one thermoplastic, aliphatic, partially aromatic or aromatic homo- and / or copolyester, preferably a polyester, more preferably a polyethylene terephthalate, preferably in the specified layer sequence, wherein, when present of two layers (h) these are preferably constructed of the same type of polymers. The adhesion promoter layers (b), (d) and (i) are preferably made of at least one modified thermoplastic polymer, preferably of at least one modified polyolefin homo- or copolymers, more preferably of at least one modified ethylene homo- or copolymers which at least one organic acid or at least one organic

Acid anhydride, preferably with maleic anhydride, modified.

In a preferred embodiment, the layers (h) and the layer (s), each independently of one another, can be composed of at least one homo- or copolyamide or mixtures thereof. In another preferred

Embodiment, the layers (h) are composed of at least one

thermoplastic olefin homo- or copolymers and / or at least one cyclo-olefin copolymers and the layer (e) is composed of at least one thermoplastic, aliphatic, partially aromatic or aromatic homo- and / or copolyester.

Regardless of the number of layers, the total thickness of the

According to the invention used, multilayer plastic film preferably 35 - 80 μηι, more preferably 50 - 70 pm.

The average density of the multilayer plastic film is

preferably at most 1, 15 g / cm ³ , more preferably at most 1, 10 g / cm ³ , and most preferably 1, 0-1, 05 g / cm ³ . The plastic film used in the invention has no metal foil, such as an aluminum foil, and no ceramic coating such. As a vapor deposition of a layer of SiO _x or Al ₂ 0 ₃ , on.

Preferably, the film tube is stretched biaxially in the longitudinal and transverse directions in each case in a drawing ratio of at least 1: 1, 5, more preferably of at least 1: 2, very particularly preferably of 1: 2 to 1: 4.

Except for the barrier layer (c), all layers of the multilayer film used according to the invention, each independently, with additives selected from the group comprising antioxidants, antiblocking agents, anti-fogging agents, antistatic agents, antimicrobial agents, light stabilizers, UV absorbers, dyes, color pigments, stabilizers, preferably Heat stabilizers, process stabilizers and UV and / or light stabilizers, preferably based on at least one sterically hindered amine (HALS), process auxiliaries,

Nucleating agents, lubricants, optical brighteners, spacers, peel additives, fillers, waxes, wetting agents, surface-active compounds,

preferably surfactants, and dispersants, to be doped. In this case, the content of the abovementioned additives - if present in one layer, in each case 0.001-20 wt .-%, preferably 0.01-10 wt .-%, particularly preferably 1-5 wt .-%, each based on the total weight of the single layer.

In a preferred embodiment, the invention used

Multilayer film transparent. The multilayer film used according to the invention may be printed or dyed. The printing is preferably carried out on the outer layer (e). For coloring, at least one layer of the multilayer film can be provided with at least one colorant, preferably with at least one colorant and / or color pigment, as an additive.

The multilayered plastic film used according to the invention is preferably obtainable overall by the blown film coextrusion process, particularly preferably by the triple bubble coextrusion process. Preferably, the multi-layered, biaxially oriented used in the invention

Plastic film made this way.

These production methods and corresponding parameters are generally known to the person skilled in the art. Thus, the production of multilayer films using the triple-bubble coextrusion process, for example in James D. Stobie, Producing coextruded high barrier heat-shrinkable packaging films, PAPER, FILM & FOIL CONVERTER, [Online] October 1, 2003, described.

In detail, the 3-bubble blown film extrusion process is referred to as the triple-bubble process, and accordingly, the resulting films are multi-layered or obtained by the triple-bubble process

Designated plastic films.

In this process, the polymer masses of a multilayer film are extruded through an annular die into a multilayer film tube, which after the Outlet of the nozzle is calibrated to a certain diameter and then immediately quenched with water.

Subsequently, this tube is heated to a polymer used in accordance with selected stretching temperature and forming a second bubble between two pairs of draw-off rollers to expand the

Bubble diameter inflated again with air or other suitable gas and thereby stretched in the transverse direction or transverse direction. The stretching in the longitudinal direction or machine direction takes place over the

Setting a different speed of the bubble longitudinally delimiting draw-off rollers. The tube expanded to a bubble thus becomes higher in comparison with the extrusion rate

Promoted speed, so that he an orientation in longitudinal or

Machine direction receives.

To remove the biaxial orientation introduced and frozen reset tension of the multilayer tube is expanded to a third bladder and fixed in the inflated state while maintaining a controlled temperature and a controlled internal bladder pressure. These

Heat treatment of the third bubble contributes in addition to the reduction of residual stresses especially to the flat position of the multilayer plastic film while maintaining the achieved by the biaxial orientation high stability and good mechanical strength.

This results in an inventively used, multilayer plastic film with a degree of shrinkage of at most 5%, preferably of <3% measured in accordance with DIN EN ISO 11501 at a water temperature of 90 ° C.

This can be considered a practically negligible shrinkage of a

multilayer, stretched plastic film can be viewed.

The multilayer plastic films used according to the invention are thermally stabilized or fixed. This ensures that the

Plastic films in further processing steps, such as bag production, printing or laminating or in a subsequent sterilization process, which sometimes act for a long duration high temperatures on the plastic films, practically do not shrink.

Another significant advantage of the multilayer films obtainable by the process described above in comparison with conventionally produced multilayer plastic films is that the multi-layered, biaxially oriented plastic films can be produced with substantially lower overall thicknesses using the triple-bubble coextrusion process

material savings. Thus, multilayer films produced by this process have a total thickness of 35-80 μm in a 11-layer structure, wherein the biaxially oriented PET layer can be present as an outer layer with a thickness of only 2 to 12 μm.

As a result, it is not only multilayer plastic films but also flat bags made therefrom that can be produced inexpensively while saving a great deal of material and thereby conserving the petroleum resources. In addition, the flat bags according to the invention, ie the packaging material used in the invention are recyclable.

The multilayer, biaxially oriented plastic film tube produced preferably by the triple-bubble method can preferably be cut laterally lengthwise after the production, wound onto a roll, and cut in a further step in-line or off-line to the required width, directly to Flat bags are further processed, possibly after printing and / or z. B. protective coating.

The multilayer plastic films used in accordance with the invention may be printed and / or provided with a thermal protective varnish.

For the production of flat bags or flat bag packaging, the biaxially stretched, multilayer film tube produced by a coextrusion method, preferably the triple bubble method, can also be used directly, d. H. be continuously divided into individual tube sections. At the tube sections, one of the two tube openings is first closed by means of a heat seal.

This one-sided still open bag is filled after filling with the

Packing Good in bottling operation via a second heat seal, preferably gas-tight, sealed.

If the flat bag made of a flattened, rolled up, according to the invention used, multi-layer, biaxially oriented plastic film is, all edges of the flat bag must be sealed by heat sealing.

The flat bags according to the invention may preferably be in the following

Application areas are used:

Flat bags for packaging powdery foods, in particular dry soups, dry sauces, filter coffee, cocoa powder,

Dried milk pudding powder, gelatin powder, powdered flavor additives, cake mixes, or as a sachet dosage form of pharmaceutical powder.

Normally, the flat bags filled in this way have an opening aid or

Aufreißhilfe, preferably in the form of a notch in the outer region of the opening provided for, sealed flat bag to the sealed seam.

Examples

The following raw materials were used in the examples:

PET Manufacturer: Dufor Resins B.V.

Density: 1.4 g / cm ³

MFI: no manufacturer's information

polyethylene terephthalate

Adhesive Manufacturer: DuPont de Nemours

Density: 0.927 g / cm ³

MFI: 2.0 g / 10 min (190 ° C / 2.16 kg)

Maleic anhydride-modified ethylene-methacrylate

copolymer

HDPE Manufacturer: Exxon Mobil Chemical

Density: 0.956 g / cm ³

MFI: 1, 2 g / 10 min (190 ° C / 2.16 kg)

Polyethylene (HD)

PA 6 Manufacturer: EMS-Chemie AG

Density: 1, 14 g / cm ³

MFI: 25.01 ml / 10min (275 ° C / 5 kg)

Polyamide 6

PA amorphous Manufacturer: EMS-Chemie AG

Density: 1, 19 g / cm ³

MFI: 21, 1 ml / 10min (275 ° C / 5 kg)

Polyamide 6I / 6T EVOH Manufacturer: Nippon Gohsei Europe GmbH

Ethylene content: 29%

Density: 1, 21 g / cm ³

MFI: 3.8 g / 10 min (190 ° C / 2.16 kg)

EthylenA inylalcohol copolymer

MDPE Manufacturer: Total Petrochemicals

Density: 0.934 g / cm ³

MFI: 0.15 g / 10 min (190 ° C / 2.16 kg)

Polyethylene (MD) comonomer: 1-hexene

LDPE Manufacturer: LyondellBasell Industries

Density: 0.924 g / cm ³

MFI: 1, 9 g / 10 min (190 ° C / 2.16 kg)

Polyethylene (LD)

LLDPE Manufacturer: Dow Chemicals

Density: 0.902 g / cm ³

MFI: 1, 0 g / 10 min (190 ° C / 2.16 kg)

Polyethylene (LLD) comonomer: 1-octene

COC manufacturer: Topas Advanced Polymers GmbH

Density: 1, 02 g / cm ³

MFI: 1, 0 g / 10 min (190 ° C / 2.16 kg)

Ethylene-norbornene copolymer Examples

% Data are in each case% by weight

The multilayer plastic films having the structure given in the examples were produced by the triple bubble process.

example 1

Layer (s) (3 pm) PET

Layer (i) (3 pm) adhesion promoter

Layer (h) (12 pm) HDPE

Layer (h) (3 pm) HDPE

Layer (d) (3 pm) adhesion promoter

Layer (g) (3 pm) Mixture of 80% PA 6 and 20% amorphous polyamide

Layer (c) (6 pm) EVOH

Layer (f) (3 pm) Mixture of 80% PA 6 and 20% amorphous polyamide

Layer (b) (3 pm) adhesion promoter

Layer 0) (6 pm) LDPE

Layer (a) (15 pm) Mixture of 50% LDPE and 50% LLDPE (mPE)

Total layer thickness: 60pm

Basis weight: «60.3 g / m ² Example 2

Layer (s) (3 μηι) PET

Layer (i) (3 μΓη) adhesion promoter

Layer (h) (12 pm) Mixture of 70% MDPE and 30% cycloolefin copolymer layer (h) (3 pm) Mixture of 70% MDPE and 30% cycloolefin copolymer layer (d) (3 pm) adhesion promoter

Layer (g) (3 pm) Mixture of 80% PA 6 and 20% amorphous polyamide

Layer (c) (6 pm) EVOH

Layer (f) (3 pm) Mixture of 80% PA 6 and 20% amorphous polyamide

Layer (b) (3 pm) adhesion promoter

Layer (j) (6 pm) LDPE

Layer (a) (15 pm) Mixture of 50% LDPE and 50% LLDPE (mPE)

Total layer thickness: 60pm

Basis weight: «60.3 g / m ²

The physical properties of the multilayer film according to Examples 1 and 2 are determined by the methods indicated and listed in the table below.

The degree of shrinkage in machines (MD) and transverse direction (TD) was determined by

Dipping a 100 mm x 100 mm large sample of film for 10 s in a water bath with a temperature of 90 ° C based on DIN EN ISO 11501 determined.

The oxygen permeability was measured according to DIN 53380-3 at 23 ° C and 0% relative humidity. Water vapor permeability was measured according to DIN EN ISO 15106-2 at 23 ° C and% relative humidity.

Claims

claims:

1. flat bag of a at least 9-layer, preferably up to 11-layer, biaxially oriented in a stretch ratio of at least 1: 1, 5 oriented plastic film, which has a water vapor permeability of max. 2 g / (m ^{2 ■} 24 h) an oxygen permeability of max. 5 cm ³ / (m ^{2 ■} 24 h ^■ bar) (at 0% relative humidity), a degree of shrinkage of not more than 5% (at 90 ° C) and a total thickness of 35 to 80 pm.

2. flat bag according to claim 1, characterized in that the

multilayer plastic film, the subsequent layer sequence

(a) a sealant layer (a) directed to the filling material, composed of at least one thermoplastic olefin homo- or copolymers, cyclo-olefin copolymers or mixtures thereof,

optionally (j) a layer (j) composed of at least one thermoplastic

Olefin homo- or copolymers, cyclo-olefin copolymers or mixtures thereof,

(b) a primer layer (b),

(f) a layer (f) composed of at least one homo- and / or

copolyamide

(c) at least one inner barrier layer (c)

(g) a layer (g) composed of at least one homo- and / or copolyamide,

(d) a primer layer (d), (h) a layer (h) composed of at least one thermoplastic olefin homo- or copolymer, a cyclo-olefin copolymer or mixtures thereof or of at least one homo- or copolyamide or mixtures thereof,

optionally (h) a further layer (h) composed of at least one

thermoplastic olefin or Copoylmeren, at least one cyclo-olefin copolymers or mixtures thereof or at least one homo- or copolyamide or mixtures thereof.

(i) a primer layer (i) and

(e) an outer layer (e) constructed on at least one

thermoplastic, aliphatic, partially aromatic or aromatic homo- or copolyamide or at least one thermoplastic, aliphatic, partially aromatic or aromatic homo- and / or copolyester.

3. flat bag according to claim 1 or 2, characterized in that the

biaxially oriented, multilayer plastic film, a sealing layer (a) composed of at least one ethylene homo- or copolymers, preferably at least one polymer selected from the group comprising ethylene homopolymers, preferably LDPE or HDPE, propylene homopolymers such as polypropylene, butylene Homopolymers, isobutylene homopolymers and mixtures thereof or an olefin copolymer selected from the group comprising ethylene and / or Propylene copolymers having at least one α-olefin having at least 4 C atoms, preferably an ethylene and / or propylene copolymers having at least one α-olefin selected from the group comprising butene, hexene and octene, or a cyclo-olefin copolymer (COC), preferably a copolymer having a cyclic (Ce to Ci2) olefin monomer, preferably norbornene or tetracyclododecene with a _(C2-C4) olefin, preferably ethylene, or mixtures of two of said polymers.

4. Flat bag according to one of claims 1 to 3, characterized in that the biaxially oriented, multilayer plastic film, a barrier layer (c) as a hydrogen, oxygen and possibly aroma barrier layer composed of at least one ethylene-vinyl alcohol copolymer, at least one Polyvinyl alcohol, at least one homo- or copolyamide or a mixture of at least two of said polymers.

5. flat bag according to one of claims 1 to 4, characterized in that the biaxially oriented, multilayer plastic film, the layer (f), the

Layer (g), the layer (c) and the layer (e), the same or different from each other, from at least one thermoplastic, aliphatic, partially aromatic or aromatic homo- or copolyamide, preferably at least a partially aromatic, amorphous or partially crystalline

Copolyamide, which is preferably in admixture with at least one other homopolyamide and / or copolyamide having.

6. flat bag according to one of claims 1 to 5, characterized in that the biaxially oriented, multilayer plastic film, an outer layer (s) composed of at least one thermoplastic, aliphatic,

partially aromatic or aromatic homo- and / or copolyester,

preferably a polyethylene terephthalic acid ester.

7. Flat bag according to one of claims 1 to 6, characterized in that the biaxially oriented, multilayer plastic film has a layer (j) composed of at least one ethylene homo- or copolymers, preferably of a mixture of at least one LDPE and LLDPE.

8. Flat bag according to one of claims 1 to 7, characterized in that the biaxially oriented, multilayer plastic film at least one, preferably two layers (h) composed of at least one

thermoplastic olefin homo- or copolymers, at least one cyclo-olefin copolymers or mixtures thereof or at least one homo- or copolyamide or mixtures thereof, preferably composed of HDPE or a mixture of COC and LLDPE.

9. Flat bag according to one of claims 1 to 8, characterized in that the biaxially oriented, multilayer plastic film is obtainable by the triple-bubble co-extrusion process.

10. Flat bag according to one of claims 1 to 9, characterized in that the biaxially oriented, multilayer plastic film has a degree of shrinkage of <3%.

11. Flat bag made of a biaxially oriented, multilayer plastic film according to claim 1 to 10 as packaging for preferably powdered food or pharmaceutical products.

12. flat bag as packaging according to claim 11 as a gas-tight packaging for dry soups, dry sauces, filter coffee, cocoa powder,

Dried milk pudding powder, gelatin powder, powdered flavor additives, cake mixes or as Sachet dosage form for powdered pharmaceuticals.