WO2018202479A1

WO2018202479A1 - Recyclable, easily tearable packaging laminate having a good barrier effect, and method for production thereof

Info

Publication number: WO2018202479A1
Application number: PCT/EP2018/060462
Authority: WO
Inventors: Achim Grefenstein; Markus Kick; Thami LAMTIGUI
Original assignee: Constantia Hueck Folien Gmbh & Co. Kg
Priority date: 2017-05-05
Filing date: 2018-04-24
Publication date: 2018-11-08

Abstract

The invention relates to a recyclable, easily tearable packaging laminate having a good barrier effect, comprising a first laminate layer (2) and a second laminate layer (3), wherein the first laminate layer (2) is a co-extruded composite, elongated in the machine direction, consisting of a substrate layer (4) having a high HDPE component of at least 60 % by volume, a connecting layer (5) and a barrier layer (6) consisting of a barrier polymer, preferably polyamide or ethylene vinyl alcohol copolymer, having a maximum thickness of 20 % of the overall thickness of the first laminate layer, wherein the connecting layer (5) is arranged between the substrate layer (4) and the barrier layer (6) and the first laminate layer (2) is connected on the barrier layer (6) thereof to the second laminate layer (3).

Description

Recyclable, easy-to-tear packaging laminate with good barrier effect and process for its production

The subject invention relates to a packaging laminate having a first laminate layer and a second laminate layer, wherein the first laminate layer comprises a barrier layer, and a method for producing such a packaging laminate.

In the packaging industry packaging laminates are used, which should have different properties depending on the application. Such packaging laminates are generally multilayer plastic films which are produced by the extrusion process, coextrusion processes (both in the flat film and blown film processes) or laminating processes (bonding of individual layers by means of a laminating adhesive), including mixtures thereof. The packaging laminate may also incorporate non-plastic layers, for example a layer of aluminum or paper. The packaging laminate also typically includes an outer sealant layer for thermosealing the packaging laminate into a desired package such as e.g. a bag, a sack, a bag, etc. to process. In another application, a packaging laminate may also be in the form of a shrinkable film, which, depending on the application, may also be of sealable but unprinted type, e.g. for the packaging of larger portions of meat, can be made.

A typical requirement for a packaging laminate is a barrier function against water vapor, oxygen and aroma. For this purpose, the packaging laminate typically contains a barrier layer of aluminum or a suitable barrier polymer, such as ethylene-vinyl alcohol copolymer (EVOH) or polyamide (PA). In addition, other layers may be included to give the packaging laminate the desired properties, such as toughness, stiffness, shrinkability, tear resistance, etc. A sealant layer is typically made of a polyolefin, typically polypropylene (PP) or polyethylene (PE) in various densities LLDPE, LDPE, MDPE or HDPE.

Of course, in order to be able to process the packaging laminate, the packaging laminate must not be thrown or rolled up (the so-called curling), which is why usually symmetrical layer structures are used.

Furthermore, it is known to change the properties of the packaging laminate by a mono- or biaxial orientation. Such orientation can be achieved by the extrusion process, for example in a multiple bubble process, or only after the extrusion process by stretching of the packaging laminate in the machine direction (in the longitudinal direction of the packaging laminate) and / or in the transverse direction (normal on the longitudinal direction). Due to the orientation of the packaging Above all, the stiffness, tensile strength and toughness can be improved. Furthermore, the orientation of the shrinkage property of the packaging laminate can be achieved that also rather cloudy materials, such as HDPE, achieve a higher transparency after stretching.

WO 2013/032932 A1 describes such a packaging laminate, for example with the structure HDPE / bonding layer / EVOH / bonding layer / sealing layer, as a shrink film. To produce the shrinkage property, the packaging laminate is stretched biaxially as a whole. However, stretching can only be carried out after the individual layers of the packaging laminate have achieved sufficient bond strength. Similar shows the WO 2009/017588 A1. WO 2013/032932 A1 and WO 2009/017588 A1, however, primarily aim at a suitable material for the bonding layer.

EP 673 759 B1 also discloses a packaging laminate for a shrink film having a barrier layer of EVOH and at least one further polymer layer, which should be compatible with the barrier layer in terms of stretching properties. As an example of the further polymer layer, an anhydride modified linear low density polyethylene (LLDPE) is mentioned.

WO 2015/175871 A1 in turn describes a packaging laminate of an HDPE layer, which is connected to a barrier layer, for example of PA, vinyl-containing or acrylate-containing polymers. Furthermore, a sealing layer, for example of LLDPE, can also be arranged on the barrier layer. The goal is to produce a recycle-friendly laminate by making the barrier layer a maximum of 5% of the total weight of the packaging laminate. The packaging laminate of WO 2015/175871 A1 is not oriented.

In many packages made of a packaging laminate, it is also desirable to be able to easily tear the packaging by hand, in particular for easy opening of the packaging. Here it is e.g. From WO 2005/1 13370 A1, it is known that a unidirectionally stretched film can be torn more easily parallel to the stretching direction than transversely thereto, and that such a film is torn parallel to the stretching direction in relation to an unstretched or bidirectionally stretched film, even with reduced tear strength can. Such a film may also be part of a laminate, which may also comprise a barrier layer of aluminum or EVOH. The unidirectionally stretched film gives the laminate good tear properties parallel to the stretching direction and substantially prevents it from tearing transversely thereto.

EP 1 769 908 A1 in turn describes that a laminate of a barrier layer (eg of EVOH) and a double-sided plastic layer can be easily torn in both directions if the plastic layer consists of a mixture of PE with a density between see 0.910 g / cm ³ and 0.960 g / cm ³ (ie LDPE, MDPE or HDPE) and a polycyclic olefin, such as a cycloolefin copolymer (COC) exists, and the laminate is subjected to a low bidirectional stretching. Such a low bidirectional stretching occurs, for example, in the extrusion in the blown film process, with which a separate step of orientation of the laminate after extrusion can be omitted. However, such a laminate is due to the proportion of COC only partially recyclable and also more expensive to produce, as a varietal material. At high COC content, up to 60% COC is mentioned in the mixture, the laminate is not recyclable at all, at least insofar as the PE content also contains larger amounts of LDPE.

It is an object of the subject invention to provide a recycler-friendly packaging laminate that is easy to manufacture and that is easily tearable in both directions. It is a further object to provide a manufacturing method for such a packaging laminate.

This object is achieved by co-extrusion of a first laminate layer consisting of a substrate layer having an HDPE content of at least 60% by volume, a tie layer and a barrier layer of a barrier polymer, preferably of polyamide or ethylene-vinyl alcohol copolymer, having a maximum thickness 20% of the total thickness of the first laminate layer, wherein the tie layer is disposed between the substrate layer and the barrier layer, subsequently stretching the coextruded first laminate layer in the machine direction, and then bonding the thus stretched first laminate layer to a second laminate layer having a polyethylene portion of at least 80% by volume, wherein the second laminate layer is bonded to the barrier layer of the first laminate layer. The packaging laminate according to the invention comprises a first laminate layer and a second laminate layer, wherein the first laminate layer is a coextruded and MD stretched composite of a substrate layer having an HDPE content of at least 60% by volume, a tie layer and a barrier layer of a barrier polymer, preferably polyamide or ethylene-vinyl alcohol copolymer having a thickness of at most 20% of the total thickness of the first laminate layer, wherein the bonding layer is disposed between the substrate layer and the barrier layer and the first laminate layer is bonded to the second laminate layer at its barrier layer.

The unidirectional stretching of the first laminate layer before lamination with the second laminate layer significantly increases the barrier effect of the first laminate layer. In addition, it has surprisingly been found that by unidirectional stretching, the first laminate layer with the defined structure can be equally easily torn in both directions. These tearing properties are impressed on the packaging laminate so that the packaging laminate itself can easily be torn in both directions. can be. In addition, the production is simplified considerably by the simple, asymmetrical structure and the only unidirectional stretching of the first laminate layer compared to conventional symmetrical, bidirectional structures, which also significantly reduces the production costs.

A machine-direction stretched (MDO) layer with a high HDPE content, especially when the HDPE content is greater than 80% and above, tends to splice longitudinally. For this reason, in PE packaging laminates such MDO layers with a high HDPE content have hitherto always been combined with the tougher LLDPE or mLLDPE, for example through a further layer of LLDPE, with a high LLDPE content being sought in the packaging laminate. It has now further surprisingly been found that the first laminate layer with such a high proportion of HDPE (even against 100% HDPE) is sufficiently tough even without such a tough LLDPE layer and does not tend to splice. The reason for this lies in the bonding layer, which gives the laminate layer the required toughness. The first laminate layer can therefore also be advantageously used as a barrier film.

Due to the good transparency of the stretched HDPE substrate layer, the optical properties of the packaging laminate can be improved if the first laminate layer is printed, metallized or coated on the barrier layer prior to bonding to the second laminate layer. In addition, the barrier effect can be increased by metallizing or coating.

For certain applications, it is advantageous if the first laminate layer on the substrate layer is joined to a further single-layer or multi-layer laminate layer. In this case, the first laminate layer may be printed, metallized or coated on the barrier layer and / or on the substrate layer. Likewise, at least one layer of the further laminate layer can be printed, metallized or coated.

For certain applications, it is advantageous if the first laminate layer is bonded to its substrate layer with a unidirectionally stretched fourth laminate layer comprising a substrate layer having an HDPE content of at least 60% by volume, a barrier layer of a barrier polymer, and a tie layer disposed therebetween. Such a packaging laminate has particularly good barrier properties.

A further advantageous embodiment results if the second laminate layer is a coextruded, MD stretched laminate of a substrate layer having an HDPE content of at least 60% by volume, preferably at least 70% by volume and most preferably at least 80% by volume of a tie layer , a barrier layer of a barrier polymer, preferably of polyamide or ethylene-vinyl alcohol copolymer, having a thickness of at most 20% of the total thickness of the second laminate layer and a sealant wherein the bonding layer of the second laminate layer is disposed between the substrate layer and the barrier layer of the second laminate layer and the sealing layer is disposed on the substrate layer and the barrier layer of the second laminate layer is bonded to the barrier layer of the first laminate layer. Such a packaging laminate also has particularly good barrier properties. In addition, the sealing layer is thereby advantageously integrated into the coextruded second laminate layer, so that no further production steps are required for the packaging laminate.

The subject invention will be explained in more detail below with reference to Figures 1 to 5, which show by way of example, schematically and not by way of limitation advantageous embodiments of the invention. It shows

1 shows a first embodiment of a packaging laminate according to the invention, FIG. 2 shows a second advantageous embodiment of a packaging laminate according to the invention,

3 shows a third advantageous embodiment of a packaging board according to the invention,

4 shows a fourth advantageous embodiment of a packaging laminate according to the invention and

5 shows an embodiment of a first laminate layer as a symmetrical barrier film.

1 shows a packaging laminate 1 according to the invention with a first laminate layer 2 and a second laminate layer 3 connected thereto.

The first laminate layer 2 in the packaging laminate 1 is stretched in the machine direction (MDO) and has an asymmetric layer structure with a substrate layer 4 and a barrier layer 6, which are interconnected by a bonding layer 5. The thickness of the first laminate layer 2 is preferably 10 to 40μη "ΐ.

Substrate layer 4 has a high density polyethylene (PE) content of at least 60% by volume, preferably at least 70% by volume, and most preferably at least 80% by volume. The proportion of HDPE can go against 100% by volume, with 100% by volume usually never being achieved due to common additives (such as slip additives, antiblocking additives, fillers, etc.). A HDPE is understood as meaning a PE with a density between 0.94-0.97 g / cm ³ . The balance is a compatible polyolefin material, preferably a linear low density polyethylene (LLDPE) (having a density between 0.87-0.94 g / cm ³ ), a low density polyethylene (LDPE) (having a density between 0.915-0.935 g / cm ³ ) or also a linear metallocene low density polyethylene (mLLDPE), in particular to increase the toughness. As a compatible polyolefin material are basically any types of polyethylenes in question, especially ethylene copolymers, such as ethylene-ene-vinyl acetate copolymer (EVA), methacrylic acid ethyl ester (EMA), ethylene / acrylic acid Copolymer (EAA) or ethylene-butyl acrylate copolymer (EBA). Also, as the compatible polyolefin material, polypropylene (PP) or a cycloolefin copolymer (COC) of not more than 20% by volume may be used. In the case of PP, preference is given to a polypropylene random copolymer with ethylene as comonomer (customary from 5 to 15%), a polypropylene copolymer with ethylene or a polypropylene homopolymer which is mixed with linear PE types, such as mLLDPE, LLDPE or HDPE is sufficiently compatible, used to achieve at least limited recyclability.

The HDPE and the compatible polyolefin material may be present in the substrate layer 4 as a mixture. However, the substrate layer 4 can also be multilayered (extruded or coextruded) with one (or more) HDPE layer and one (or more) layer of the polyolefin material. The thickness of the substrate layer 4 is preferably 5 to 35μη "ΐ.

The barrier layer 6 consists of a barrier polymer, ie a polymer with a sufficient barrier property, in particular against oxygen, hydrogen and / or aroma. The barrier polymer is preferably a polyamide (PA) or an ethylene-vinyl alcohol copolymer (EVOH). Preferably, EVOH is used as a barrier polymer. The barrier layer 6 has a maximum thickness of 20%, preferably 5 to 10%, of the total thickness of the first laminate layer 2, ie a maximum of 2 to δμηη. Due to the small thickness of the barrier layer 6, the recycling friendliness is not impaired.

The connecting layer 5 is used to connect the barrier layer 6 and the substrate layer 4. In this case, a sufficient bond should be achieved adhesion, in particular to prevent unwanted delamination of the first laminate layer 2 safely. Suitable tie layers 5 are preferably made of polymers having increased polarity, for example based on maleic anhydride-modified polyolefins (such as PE or PP), ethylene-vinyl acetate copolymer (EVA), ethylene / acrylic acid copolymer (EAA), ethylene-butyl acrylate copolymer ( EBA), or similar polyolefin copolymers. The thickness of a connecting layer 5 is at most 10% of the total thickness of the first laminate layer 2, typically 1 to 5μη "ΐ.

The second laminate layer 3 consists predominantly of a PE, wherein the PE content of the total amount of polymer of the second laminate layer 3 without any added mineral or other fillers should be at least 80% by volume. Here, different types of PE, ie LDPE, LLDPE, MDPE, HDPE varietal or even as a mixture or in the form of co-polymers or even multilayer can be used. Depending on the application of the packaging laminate 1, the thickness of the second laminate layer 3 is typically between 20 and 200 μm. Of course, in the second laminate layer 3 as well, for the desired recyclability, the remainder remaining will consist of a compatible polyolefin material as described above.

By using predominantly PE and compatible materials in the packaging laminate 1, it is possible to produce a laminate which is particularly easy on reycyling, and which can be recycled easily and inexpensively by conventional methods in mechanical recycling.

The first laminate layer 2 is produced by coextrusion, because this allows a particularly simple, cost-effective production. The known blown film or flat film extrusion process is preferably used.

The first laminate layer 2 is stretched after co-extrusion exclusively in the machine direction (usually the longitudinal or extrusion direction). The degree of stretching is preferably at least 4: 1 in the machine direction. Stretching can be done in-line (ie immediately after co-extrusion) or off-line (ie at a later time after co-extrusion). Unidirectional stretching can be performed much easier and less costly than bidirectional stretching, which can reduce manufacturing costs.

It should be noted here that in blown film extrusion and flat film extrusion the extrusion gap (in the blown film 1, 5 to 2.5 mm) or the gap of the extrusion die is significantly larger than the final thickness of the extruded foil (typically between 10 to 200 μηι ). For this purpose, the extruded melt is stretched at temperatures well above the melting point of the extruded polymer, thereby obtaining the final thickness. In blown film extrusion, the melt is e.g. typically in the transverse direction by a factor of about 2 to 3 (the so-called blow-up ratio) and in the longitudinal direction by a factor of 1:10 to 1: 100 (the so-called draw-off ratio). However, this stretching in extrusion can not be compared with the stretching of a plastic film, since the stretching is usually carried out at temperatures just below the melting point of the polymer in order to align the disordered polymers and the semi-crystalline regions by stretching in the stretching direction.

An asymmetrical structure of the first laminate layer 2 with an orientation in the machine direction is untypical and has hitherto been avoided in practice, in particular in the blown film, since it was assumed that such a structure, in particular due to water absorption of the polar barrier layer 6, curls (Curling ), which would make further processing difficult or impossible. However, it has been shown that the curling in the specific design of the structure happens to an acceptable degree, which is not hindering for further processing. For this it is advantageous if the first laminate layer 2 is connected very promptly after production with the second laminate layer 3, to thereby reduce the water absorption of the barrier layer 6 in particular. Under certain circumstances, it may also be necessary or useful to protect the coextruded film roll with the first laminate layer 2 until it is laminated by means of suitable packaging prior to the water absorption.

The advantage of the atypical asymmetrical structure of the first laminate layer 2, however, lies above all in the fact that only a single expensive and less rigid connecting layer 5 is required. Thus, the cost of the first laminate layer 2 can be reduced and a stiffer first laminate layer 2 can be achieved. The higher stiffness is particularly advantageous when using the packaging laminate 1 for producing a bag.

Further advantages of the first laminate layer 2 according to the invention result from the stretching. This results in a high transparency, especially the substrate layer 4. The stretching of the barrier layer is achieved in comparison to the unstretched similar barrier polymer about three to four times increased barrier values, whereby less expensive barrier polymer can be used with the same barrier effect. As a result, the cost of the first laminate layer 2 can be significantly reduced.

It has further surprisingly been found that such a first laminate layer 2, despite the orientation only in the machine direction in both directions, ie in the machine direction and also transversely to it) can be easily torn by hand without the film stretched in excess impermissibly in the transverse direction becomes.

Preferably, the first laminate layer 2 is produced by the blown film extrusion process because this results in less edge portion due to production, which leads to lower costs of the packaging laminate 1, especially in the case of the more expensive barrier polymers. In blown film extrusion, even more viscous HDPE materials with a MFI (Mass Flow Index) of less than 3 can be used. Such HDPE materials have a higher molecular weight and better mechanical properties, which is favorable for use in a packaging laminate 1. However, such a material would break particularly easily in the longitudinal direction and it comes even to undesirable splitting in the longitudinal direction. This undesirable property can be eliminated by incorporating the HDPE material having an MFI of less than 3 into a first laminate layer 2 as described and even achieving uniform tearing in both directions.

A first laminate layer 2 stretched in the machine direction, with a substrate layer 4, a barrier layer 6 and a bonding layer 5 as stated, also tends to have 60% by volume, in particular even at very high HDPE contents of more than 80% by volume, despite the high HDPE content. to 100% by volume, not for splicing in the longitudinal direction, as has been surprisingly found. This effect occurs both in the case of an asymmetrical Construction of the first laminate layer 2, as well as in a symmetrical structure of the first laminate layer 2 a. This observed effect is demonstrated for a first laminate layer 2 as a barrier film by the following examples in Table 1.

Table 1

In Table 1, tensile strength in the longitudinal direction (MD) and transverse direction (TD) is given in N / 15 mm and measured according to ASTM D882, the elongation at break (MD) and transverse direction (TD) are given in% and measured according to ASTM D882 and the tear propagation resistance in longitudinal direction (MD) and transverse direction (TD) in N and measured according to DIN EN ISO 6383-1. The thickness is the total thickness of the respective film and given in μηι. Sheet A in Table 1 is a 10% by volume MDO HDPE monofilm LDPE. Film A is constructed as a five-layer coextrusion film with 10% by volume of mLLDPE in all five layers of the same thickness (composition 1/1/1/1/1). The stretch ratio in the machine direction is 6: 1. Such a film 1 tends to splice in the longitudinal direction, which is particularly recognizable by the very low tensile strength and elongation at break in the transverse direction. The tear strength in the longitudinal direction is also significantly lower than in the other comparative films in Table 1, which is likewise an indication of the splice tendency in the longitudinal direction.

Film B is also a five-layer coextrudate with the film structure 95% HDPE + 5% LLDPE / 100% HDPE / 60% HDPE + 40% LLDPE / 100% HDPE / 100% HDPE. The stretch ratio in the machine direction is 6: 1. Consequently, in the film B, a tough component (LLDPE) in higher proportions (40%) was admixed in at least one layer in order to reduce the tendency to splice. This is evident from the higher values of the transverse tensile strength, the transverse elongation at break (TD) and the tear propagation resistance in the longitudinal direction, compared to film A.

However, the better effect is achieved with a barrier film C. The barrier film C is a five-layer coextrudate with the film structure 95% HDPE + 5% LLDPE / 100% HDPE / 60% HDPE + 40% LLDPE / tie layer 5 / EVOH barrier layer 6. The stretch ratio of the coextruded barrier film 3 in the machine direction is 5: 1. The substrate layer 4 is in three layers (layer thicknesses 4 μηι / 4 μηι / 8 μηι) with a HDPE content of -78% vol% in the substrate layer 4. The compound layer 5 is in the barrier film C 2 μηη, ie 10% of the total thickness, and the barrier layer 5 also 2 μηη, so 10% of the total thickness. This results in a 2/2/4/1/1 structure of the barrier film C. By the bonding layer 5, the barrier film C receives sufficient toughness to significantly reduce the splice tendency in the longitudinal direction. This is evident from the significantly higher values of transverse elongation at break (TD) and tear strength in the longitudinal direction. The tensile strength in the transverse direction is comparable to the film B.

It was particularly surprising that for this effect it makes almost no difference if the proportion of HDPE in the substrate layer 4 is further increased, as shown by the barrier film D. The barrier film D is a five-layer coextrudate with the film structure 95% HDPE + 5% LLDPE / 100% HDPE / 100% HDPE / tie layer 5 / EVOH Barrier Layer 6. The low LLDPE content in the outermost layer serves primarily to improve the surface properties of the film Barrier film D to modify to improve the processing properties. The stretch ratio in the machine direction is again 5: 1. The substrate layer 4 is in three layers (layer thicknesses 4 μηη / 4 μηη / 8 μηη) with a HDPE content of -97% Vol% in the substrate layer 4. The compound layer 5 is in the barrier film D 2 μηη, ie 10% of Total thickness, and the barrier layer 5 also 2 μηη, ie 10% of the total thickness. This results in a 2/2/4/1/1 structure of the barrier film D. In the barrier film D, the tear propagation behavior in the longitudinal direction and transverse direction is even particularly uniform.

Table 1 describes only asymmetric film constructions of the MDO barrier film 11. For the first laminate layer 2 in use as inventive barrier film 1 1 but also symmetrical structures in question (as shown in Figure 5), for example in the form of substrate layer 4 of 100 vol% HDPE / compound layer 4 / EVOH barrier layer 6 / compound layer. 4 / Substrate layer 5 of 100 vol% HDPE. In one (or both) of the substrate layers 4, a low mLLDPE or LLDPE content (for example, 5 to 10% by volume) could also be mixed, preferably in one of the outermost layers, to modify the processing properties. In such a symmetrical structure, the two outer substrate layers 4 can also be made thicker than the inner layers, that is, for example in the form of a x / 1/1/1 / x, structure with x> 1, in particular x = 1 .5, 2 , 3 or 4.

Such a first laminate layer 2 alone as a barrier film 1 1 is also considered inventive and is characterized in particular by at least one substrate layer 4, which has a HDPE content of at least 60% by volume, preferably at least 80% by volume, and which is connected via a connecting layer 5 as described above with a barrier layer 6 as described above. The substrate layer 4 can also be constructed in multiple layers. In addition, the barrier layer 6 may be connected to a further substrate layer 4 as described above for a symmetrical structure by means of a further connection layer 5 as described above. Such a barrier film 11 is produced by co-extrusion and subsequent stretching in the machine direction. The degree of stretching is preferably at least 4: 1 in the machine direction. Stretching can be done inline (ie immediately after co-extrusion) or off-line (ie at a later time after co-extrusion).

For the production of the packaging laminate 1, the stretched first laminate layer 2 and the second laminate layer 3 are joined together, preferably by extrusion lamination, extrusion coating or adhesive lamination, wherein the second laminate layer 3 is joined to the barrier layer 6 of the first laminate layer 2. In the extrusion coating, the second laminate layer 3 is extruded onto the barrier layer 6 of the first laminate layer 2, whereby a bonding agent should preferably also be provided therebetween. During lamination, the second laminate layer 3 is connected to the barrier layer 6 by means of a suitable laminating adhesive, for example based on polyurethane adhesives or else polyolefin copolymers in the extrusion lamination. The thickness of the laminating adhesive is preferably 2 to 5 g / m ² in the case of conventional adhesives based on polyurethane or 5 to 20 g / m ² in the extrusion lamination.

It has been found in suitable second laminate layers 3 that also the entire packaging laminate 1 assumes the tear properties of the first laminate layer 2, i. that the packaging laminate 1 is equally easy to tear in both directions by hand. The first laminate layer 2 thus imprints the tearing properties on the packaging laminate 1.

The second laminate layer 3 preferably forms a sealing layer 7, which in a packaging from the packaging laminate 1 generally faces the packaged product. The packaging is produced by cutting, folding and thermosealing the packaging laminate 1. Possible packages are pouches, bags, sacks, etc. The second laminate layer 3 can also have a multilayered construction, for example extruded or coextruded, as indicated in FIG. 2 and described in detail below. However, the second laminate layer 3 can also be provided with a barrier function and can also be stretched, as indicated in FIG. 4 and described in detail below.

In a further embodiment of the packaging laminate 1, as shown in FIG. 2, the first laminate layer 2 is joined on the side of the barrier layer 6 to the second laminate layer 3 and on the side of the substrate layer 4 with a further laminate layer 10, here a third laminate layer 8. The third laminate layer 8 is preferably a single- or multi-layered polymer film, for example a predominantly PE (at least 80% by volume PE) film, as described with respect to the second laminate layer 3. The third laminate layer 8 may again be either extrusion-coated or adhesive-laminated onto the first laminate layer 2, as explained with reference to the sealing layer 7 in FIG. Such a packaging laminate 1 according to Figure 2 can be used for example for the production of tubes. In this case, the thickness of the second laminate layer 3 and the third laminate layer 8 is typically in the range of 150μηι.

It is further indicated in FIG. 2 that the second laminate layer 3 can also have a multilayer structure, here for example with two layers 7 a, 7 b, which form the sealing layer 7. The same applies to the third laminate layer 8. Such a structure of the second laminate layer 3 can of course also be provided in an embodiment according to FIG.

It is also possible to metallize and / or to print and / or to coat the stretched first laminate layer 2 after stretching on the barrier layer 6 (for example with aluminum oxide or silicon oxide) before the first laminate layer 2 is joined to the second laminate layer 3. Preferably, it is metallized with aluminum. The HDPE substrate layer 4 is, especially after stretching, sufficiently transparent, so that the printed image, the metallization or the coating through the substrate layer 4 is visible. For the purpose of printing, the barrier layer 6 can also be subjected to a pretreatment of the surface to be printed, for example a corona or flame treatment, in order to improve the adhesion of the print layer to the barrier layer 6. However, alternatively or additionally, the substrate layer 4 may also be printed, metallized or printed, both on the side facing the barrier layer 6 and on the other side, optionally again after a surface treatment. In this case, common printing methods can be used, for example, a gravure printing method or a Flexod jerking method.

The third laminate layer 8 could, in addition to or as an alternative to the first laminate layer 2, be printed, metallized or coated on one or both sides.

In an advantageous embodiment of the embodiment of Figure 2, the barrier layer 6 of the first laminate layer 2 is metallized, preferably with aluminum, to increase the barrier effect. In addition, the third laminate layer 8 could be printed on the outside.

3, a further embodiment of a packaging laminate 1 according to the invention is described, which can preferably be used for the production of tubes used. Here, the first laminate layer 2 is connected to the barrier layer 6 as in the example of FIG. 1 with the second laminate layer 3. The first laminate layer 2 is at the Substrate layer 4 with a further laminate layer 10, here a fourth laminate layer 2 ', connected, which has the same structure as the first laminate layer 2 and which is also unidirectionally stretched. The fourth laminate layer 2 'thus again comprises a substrate layer 4', which is connected to a connection layer 5 'with a barrier layer 6'. Here, the barrier layer 6 'of the fourth laminate layer 2' is connected to the substrate layer 4 of the first laminate layer 2, preferably with a suitable laminating adhesive as described above. These layers of the fourth laminate layer 2 'are constructed and assembled as already described above. The fourth laminate layer 2 'consists primarily of PE materials with at least 80% by volume PE fraction. However, the thicknesses and the exact compositions or materials of the individual layers of the first laminate layer 2 and of the fourth laminate layer 2 'need not be overstated.

In this embodiment too, the fourth laminate layer 2 'may be printed, metallized or coated on the substrate layer 4' and / or on the barrier layer 6 ', in addition to or as an alternative to the first laminate layer 2. In a particularly advantageous embodiment, the fourth laminate layer 2 'is printed, preferably at its barrier layer 6', and the first laminate layer 2 metallized, preferably on the barrier layer 6 or substrate layer 4. Thus, the barrier effect of the packaging laminate 1 can be increased. However, it is also possible to provide a coating of aluminum oxide or silicon oxide on the barrier layer 6 or substrate layer 4 of the first laminate layer 2 to increase the barrier effect again.

4, a further advantageous embodiment of the invention will be described. In this case, the second laminate layer 3 is again embodied as multi-layered and comprises a substrate layer 4 ", barrier layer 6" and a bonding layer 5 ", similar to the first laminate layer 2. For these layers and also for the production of the second laminate layer 3 in this embodiment, this applies The second laminate layer 3 additionally comprises a sealing layer 7 in this embodiment. The sealing layer 7 is preferably made of a PE material, such as, for example, mLLDPE, LLDPE, or from another suitable thermoplastic, for example polypropylene (PP), but this second laminate layer 3 with the sealing layer 7 still applies that it consists of at least 80% by volume PE The sealing layer 7 of the second laminate layer 3 is joined to the other layers of the second laminate layer 3. The second laminate layer 3 of Figure 4 is coextruded as the first laminate layer 2 and as described above. In this embodiment, the sealing layer 7 is thus integrated in a multi-layered, stretched barrier film, which is constructed similarly to the first laminate layer 2. Thus, this second laminate layer 3 has substantially the same tear properties as the first laminate layer 2. In this embodiment, the unidirectionally stretched first laminate layer 2 and the unidirectionally stretched wide laminate layer 3 are joined together at the abutting barrier layers 6, 6 ", preferably by adhesive lamination using an adhesive layer 9. A suitable laminating adhesive is for example a polyurethane or polyurethane based adhesive The thickness of the laminating layer 9 is preferably 2 to 5 g / m ² .

Also in this embodiment, one (or more) of the layers of the packaging laminate 1 may be printed, metallized or coated.

In the embodiment, of course, a further laminate layer 10 (for example a third laminate layer 8 or fourth laminate layer 2 'as described above) could of course also be provided on the first laminate layer 2, as indicated in FIG.

The packaging laminate 1 according to the invention thus has at least one asymmetrical, non-directionally stretched, first laminate layer 2 of at least 60% by volume HDPE with a substrate layer 4, a barrier layer 6 and a bonding layer 5 and a second laminate layer 3 connected therewith, which forms a sealing layer 7, with a PE content of at least 80% by volume. As described above, on the side of the first laminate layer 2 facing away from the second laminate layer 3, a further single-layer or multi-layer laminate layer 10 (eg, a third laminate layer 8 or fourth laminate layer 2 ') having a PE content of at least 80 may be applied to this packaging laminate 1 Vol% be arranged. This further single-layer or multi-layer laminate layer 10 is thus connected to the substrate layer 4 of the first laminate layer 2.

In a packaging made of a packaging laminate 1 according to the invention, the sealing layer 7 of the packaging laminate 1 advantageously faces the inside of the packaging.

By printing on at least one layer of the first laminate layer 2, second laminate layer 3 or the further laminate layer 10 of a packaging laminate 1 according to the invention with a barrier lacquer, for example polyvinyl alcohol (PVOH), the barrier effect of the packaging laminate 1 can be further increased in this way. Such paint layers can be applied very thinly, typically in the range of 0.5 to 2.0 g / m ² , and thus do not affect the recycling friendliness of the packaging laminate 1.

Finally, it should be noted that each of the above-described layers in the first laminate layer 2, second laminate layer 3 or the further laminate layer 10 itself can again be constructed in multiple layers.

Claims

claims

1 . A method of manufacturing a packaging laminate (1) comprising the steps

Co-extrusion of a first laminate layer (2) consisting of a substrate layer (4) with an HDPE content of at least 60% by volume, preferably at least 70% by volume and most preferably at least 80% by volume, of a bonding layer (5) and a barrier layer ( 6) of a barrier polymer, preferably of polyamide or ethylene-vinyl alcohol copolymer, with a maximum thickness of 20% of the total thickness of the first laminate layer (2), wherein the bonding layer (5) between the substrate layer (4) and the barrier layer (6) is arranged

Stretching the coextruded first laminate layer (2) in the machine direction,

Bonding the thus stretched first laminate layer (2) to a second laminate layer (3) having a polyethylene content of at least 80% by volume, the second laminate layer (3) being joined to the barrier layer (6) of the first laminate layer (2).

2. The method according to claim 1, characterized in that the first laminate layer (2) before being bonded to the second laminate layer (3) printed on the barrier layer (6), metallized or coated.

3. The method according to claim 1 or 2, characterized in that the first laminate layer (2) on the substrate layer (4) with a further single or multi-layer laminate layer (10) having a polyethylene content of at least 80% by volume is connected.

4. The method according to claim 3, characterized in that the first laminate layer is printed, metallized or coated on the barrier layer (6) and / or on the substrate layer (4) prior to bonding to the further laminate layer (10).

5. The method according to claim 3, characterized in that at least one layer of the further laminate layer (10) is printed, metallized or coated.

6. The method according to claim 3, characterized in that the first laminate layer (2) is bonded to the substrate layer (4) with a multilayer further laminate layer (10) in the form of a unidirectionally stretched fourth laminate layer (2 ') comprising a substrate layer (4 ') having an HDPE content of at least 60% by volume, a barrier layer (6') of a barrier polymer and a tie layer (5 ') disposed therebetween, the barrier layer (6') of the fourth laminate layer (2 ') having the substrate layer (4) is joined to the first laminate layer (2).

7. The method according to claim 1 or 2, characterized in that the first laminate layer (2) is connected to a second laminate layer (3) consisting of a substrate layer (4 ") having an HDPE content of at least 60% by volume, preferably at least 70 Vol% and very particularly preferably at least 80% by volume of a bonding layer (5 "), a barrier layer (6") of a barrier polymer, preferably of polyamide or ethylene-vinyl alcohol copolymer, having a thickness of not more than 20% of the total thickness of second laminate layer (3) and a sealing layer (7), wherein the layers are co-extruded, the bonding layer (5 ") of the second laminate layer (3) between the substrate layer (4") and the barrier layer (6 ") second laminate layer (3 ) and the sealing layer (7) is disposed on the substrate layer (4 ") and wherein the coextruded second laminate layer (3) is stretched in the machine direction, and wherein the barrier layer (6") of the second laminate layer (3) is aligned with the Barrier layer (6) of the first laminate layer (2) is connected.

8. A packaging laminate comprising a first laminate layer (2) and a second laminate layer (3), wherein the first laminate layer (2) comprises a coextruded and MD stretched composite of a substrate layer (4) having an HDPE content of at least 60% by volume, a bonding layer (5) and a barrier layer (6) of a barrier polymer, preferably of polyamide or ethylene-vinyl alcohol copolymer, having a thickness of at most 20% of the total thickness of the first laminate layer, wherein the bonding layer (5) between the substrate layer (5) 4) and the barrier layer (6) is arranged and the first laminate layer (2) at the barrier layer (6) with the second laminate layer (3) is connected.

9. Packaging laminate according to claim 8, characterized in that the barrier layer (6) of the first laminate layer (2) is printed, metallized or coated.

10. Packaging laminate according to claim 8 or 9, characterized in that the first laminate layer (2) is connected to the substrate layer (4) with a further single or multilayer laminate layer (10) having a polyethylene content of at least 80% by volume.

1 1. Packaging laminate according to claim 10, characterized in that at least one layer of the further laminate layer (10) is printed, metallized or coated.

12. Packaging laminate according to claim 10 or 11, characterized in that the further laminate layer (10) comprises a fourth laminate layer (2 ') in the form of a co-extruded and MD stretched composite of a substrate layer (4') with an HDPE portion of at least 60% by volume, a barrier layer (6 ') of a barrier polymer, preferably of polyamide or ethylene-vinyl alcohol copolymer, and a tie layer (5') interposed therebetween, and the substrate layer (4) of the first laminate layer (2) having the Barrier layer (6 ') of the fourth laminate layer (2') is connected.

13. Packaging laminate according to claim 8 or 9, characterized in that the second laminate layer (3) comprises a co-extruded MD stretched laminate a substrate layer (4 ") with an HDPE content of at least 60% by volume, and more preferably at least 80% by volume, of a bonding layer (5"), a barrier layer (6 ") of a barrier polymer, preferably Polyamide or ethylene-vinyl alcohol copolymer, with a maximum thickness of 20% of the total thickness of the second laminate layer (3) and a sealing layer (7), wherein the bonding layer (5 ") of the second laminate layer (3) between the substrate layer (4" ) and the barrier layer (6 ") second laminate layer (3) is arranged and the sealing layer (7) on the substrate layer (4") is arranged and that the barrier layer (6 ") of the second laminate layer (3) with the barrier layer (6) the first laminate layer (2) is connected.