Patent Application
20180244092
The present invention relates to the technical field of dimensionally stable food containers made of packaging laminates, wherein these containers include the folded packaging laminate. The present invention in particular relates to a process including, as steps
The invention further relates to a printed sheetlike composite; to a container precursor, and also to a container, in each case including the printed sheetlike composite; to a device for the printing of a sheetlike composite; and to a use of the device for the printing of a sheetlike composite.
The prior art discloses dimensionally stable food containers made of multilayer laminates, for which the term sheetlike composites is also used here. These containers are obtained by folding of, and sealing between, certain regions of the laminate. The dimensional stability of the container is achieved here in that the laminate includes a carrier layer, which often comprises paperboard or cardboard. Foods can be stored for a long period in these food containers with minimal impairment. The sheetlike composites are typically composed of the carrier layer, mostly composed of paperboard or of paper, an adhesion-promoter layer, a barrier layer and a further plastics layer, as disclosed inter alia in WO 90/09926 A2.
The containers described above usually have a printed decor on their external side. This can be used to provide, directly on the container, information relevant for the consumer of the food included in the container, an example being the ingredients of the food. The decor moreover serves for promotional purposes and serves to provide an attractive appearance to the product. The prior art applies the decor to the laminate via an intaglio printing process before the folding of the laminate. This is achieved by using a printing roll with a large number of recesses, known as cells. The cells contain a printing ink which is received by the laminate when the laminate surface to be printed is pressed into contact. The cells of the printing roll therefore correspond to the individual pixels of the printed decor. In order to achieve a printed image of the best possible quality, it is necessary that almost every cell applies sufficient printing ink to the laminate. If the laminate receives too little, or no, printing ink from a cell, the corresponding pixel is absent in the printed image. Another term used to describe this is “missing dots”. For an acceptable printed image there is a maximal acceptable proportion of missing dots. The number of missing dots produced during printing generally increases with the roughness of the laminate surface to be printed, for example a surface of a paperboard layer. Reception of the printing ink by the laminate here is rendered more difficult in that the liquid printing ink forms a meniscus in the cells. The surface of the printing ink in the cells is therefore concave, i.e. curved away from the laminate. This means that the only laminate surfaces that can be printed satisfactorily are those that do not exceed a certain roughness. The surface roughness of the laminate here is determined significantly by the paperboard layer. The paperboard layer therefore mostly requires complicated treatment in order to attain a laminate surface that is relatively smooth and that can be printed with good results. To this end, the paperboard layer is by way of example equipped with one or more coated layers. This leads to considerably increased costs in container production.
In general terms, it is an object of the present invention to overcome, at least to some extent, a disadvantage arising from the prior art. Another object of the invention is to provide a dimensionally stable food container made of a packaging laminate with a decor which exhibits an improved printed image. Another object of the present invention is to provide a dimensionally stable food container made of a packaging laminate with a decor, wherein the decor exhibits an equally good or improved printed image on a relatively rough printed surface. Another object of the invention is to provide a dimensionally stable food container made of a packaging laminate with a decor, wherein the decor has been printed directly onto a paperboard layer or paper layer of the packaging laminate. Another object of the invention is to provide a dimensionally stable food container made of a packaging laminate with a decor, wherein the decor has lower weight per unit area for the same area coverage. Another object of the invention is to provide a dimensionally stable food container made of a packaging laminate with a decor, wherein the decor has a wider area coverage range. Another object of the invention is to provide a dimensionally stable food container made of a packaging laminate with a decor, wherein the food container can be produced cheaper. Another object of the invention is to provide a dimensionally stable food container with one of the above advantages, wherein the decor has been obtained via intaglio printing. Another object of the invention is to provide one of the above advantageous dimensionally stable food containers made of a packaging laminate, wherein the packaging laminate includes an electrically conductive barrier layer, preferably made of aluminium.
The independent claims provide a contribution to achievement, at least to some extent, of at least one of the above objects. The dependent claims provide preferred embodiments which contribute to achievement, at least to some extent, of at least one of the objects.
An embodiment 1 of a process including, as steps,
An inventive embodiment 2 of the process is designed according to the embodiment 1, wherein the process further includes a step of
It is preferable that in step e) the sheetlike composite is earthed on the external surface. The reduction in step e) can be achieved by way of example by means of earthing or else of an electrode with electrical voltage opposite to that of the sheetlike composite.
An inventive embodiment 3 of the process is designed according to the embodiment 1 or 2, wherein the barrier layer is electrically insulating. The increase is preferably achieved here in step c) in that electrical charge carriers are applied from an electrode onto a further component, and the further component applies electrical charge carriers to the internal surface of the sheetlike composite via contact with the internal surface of the sheetlike composite. An electrical charge difference exists here between the first component and the further component.
An inventive embodiment 4 of the process is designed according to any of the preceding embodiments, wherein the increase in step c) is achieved via application of electrical charge carriers from an electrode onto the external surface of the sheetlike composite.
An inventive embodiment 5 of the process is designed according to embodiment 1, 2 or 4, wherein the barrier layer is electrically conductive.
An inventive embodiment 6 of the process is designed according to the embodiment 5, wherein the barrier layer includes a metal or a metal oxide or both, or in each case preferably consists thereof. A preferred metal is aluminium.
An inventive embodiment 7 of the process is designed according to any of the preceding embodiments, wherein the sheetlike composite has been brought into contact with a further component in step c) or d), or in both, wherein the further component moves in a further direction, wherein the further direction differs from the first direction. It is preferable here that the sheetlike composite has been brought into contact at its internal surface with the further component. It is preferable that the further component guides the sheetlike composite. It is preferable that the first direction is opposite to the further direction.
An inventive embodiment 8 of the process is designed according to any of the preceding embodiments, wherein the first component rotates, wherein the first direction is a first direction of rotation.
An inventive embodiment 9 of the process is designed according to the embodiment 7 or 8, wherein the further component rotates, wherein the further direction is a further direction of rotation.
An inventive embodiment 10 of the process is designed according to any of the preceding embodiments, wherein the sheetlike composite is printed in step d) via intaglio printing.
An inventive embodiment 11 of the process is designed according to any of the preceding embodiments, wherein the first component has been earthed.
An inventive embodiment 12 of the process is designed according to any of the preceding embodiments, wherein the sheetlike composite is characterized by an ignition residue in the range from 0.1 to 75 mg, preferably from 0.2 to 50 mg, most preferably from 0.3 to 30 mg.
An inventive embodiment 13 of the process is designed according to any of the preceding embodiments, wherein the sheetlike composite further includes a polymeric external layer on one side of the carrier layer, wherein the said side faces towards the external surface, wherein a layer thickness of the polymeric external layer is in the range from 1 to 30 μm, preferably from 2 to 25 μm, most preferably from 3 to 20 μm.
An inventive embodiment 14 of the process is designed according to any of the preceding embodiments, wherein the sheetlike composite is superimposed by a colour layer on the external surface in step d), wherein the colour layer is characterized by a number of absent matrix dots in the range from 0 to 100, preferably from 0 to 70, more preferably from 0 to 60, more preferably from 0 to 40, more preferably from 0 to 30, more preferably from 0 to 20, more preferably from 0 to 10, most preferably from 0 to 8, in each case per 100 mm2.
An inventive embodiment 15 of the process is designed according to any of the preceding embodiments, wherein the sheetlike composite is superimposed on the external surface in step d) by a colour layer, wherein the colour layer includes a first colour layer region and a further colour layer region, wherein the first colour layer region is characterized by area coverage of at least 50%, preferably of at least 60%, more preferably of at least 70%, more preferably of at least 80%, most preferably of at least 90%, wherein the further colour layer region is characterized by an area coverage in the range from more than 0 up to 15%, preferably from more than 0 up to 13%, more preferably from more than 0 up to 11%, more preferably from more than 0 up to 9%, most preferably from more than 0 up to 5%, wherein the first colour layer region adjoins the further colour layer region. It is preferable that the abovementioned area coverages refer to the same colour.
An inventive embodiment 16 of the process is designed according to any of the preceding embodiments, wherein the external surface is a surface of the carrier layer.
An inventive embodiment 17 of the process is designed according to any of the preceding embodiments, wherein the polymeric internal layer includes from 10 to 90% by weight, based on the total weight of the polymeric internal layer, of a polymer produced by means of a metallocene catalyst. A preferred polymer polymerized by means of a metallocene catalyst is an mPE.
An inventive embodiment 18 of the process is designed according to any of the preceding embodiments, wherein the polymeric internal layer includes a polymer blend, wherein the polymer blend includes from 10 to 90% by weight of an mPE and at least 10% by weight of a further polymer, based in each case on the total weight of the polymer blend.
An inventive embodiment 19 of the process is designed according to any of the preceding embodiments, wherein the carrier layer includes, preferably consists of, one selected from the group consisting of paperboard, cardboard, and paper, or a combination of at least two thereof.
An inventive embodiment 20 of the process is designed according to any of the preceding embodiments, wherein the carrier layer has at least one hole, wherein the hole has been covered at least by the barrier layer and at least by the polymeric internal layer as hole-covering layers. The hole-covering layers are in each case the layers covering the at least one hole.
An inventive embodiment 21 of the process is designed according to any of the preceding embodiments, wherein the external surface is not included by a covering layer of the carrier layer. A preferred covering layer is a “paper-coating layer”.
An embodiment 1 of a printed sheetlike composite 1 obtainable via the process according to any of the embodiments 1 to 21 makes a contribution to achievement of at least one of the objects of the invention.
An inventive embodiment 2 of the printed sheetlike composite 1 is designed according to the embodiment 1, wherein the external surface of the sheetlike composite has been joined to a colour layer, wherein the colour layer is characterized by a number of absent matrix dots in the range from 0 to 100, preferably from 0 to 70, more preferably from 0 to 60, more preferably from 0 to 40, more preferably from 0 to 30, more preferably from 0 to 20, more preferably from 0 to 10, most preferably from 0 to 8, in each case per 100 mm2. It is preferable that the external surface has been printed with the colour layer.
An inventive embodiment 3 of the printed sheetlike composite 1 is designed according to the preceding embodiment, wherein the colour layer includes a first colour layer region and a further colour layer region, wherein the first colour layer region is characterized by an area coverage of at least 50%, preferably of at least 60%, more preferably of at least 70%, more preferably of at least 80%, most preferably of at least 90%, wherein the further colour layer region is characterized by an area coverage in the range from more than 0 up to 15%, preferably from more than 0 up to 13%, more preferably from more than 0 up to 11%, more preferably from more than 0 up to 9%, most preferably from more than 0 up to 5%, wherein the first colour layer region adjoins the further colour layer region. It is preferable that the abovementioned area coverages refer to the same colour.
An embodiment 1 of device including, as device constituents,
An inventive embodiment 2 of the device is designed according to the preceding embodiment, wherein the device includes a further electrode downstream of the first component, wherein the further electrode is arranged and designed for acceptance of electrical charge carriers from the external surface of the sheetlike composite.
An inventive embodiment 3 of the device is designed according to the embodiment 1 or 2, wherein the barrier layer is electrically insulating.
An inventive embodiment 4 of the device is designed according to the embodiment 1 or 2, wherein the barrier layer is electrically conductive.
An inventive embodiment 5 of the device is designed according to the embodiment 4, wherein the barrier layer includes a metal or a metal oxide or both, or preferably consists thereof. A preferred metal is aluminium.
An inventive embodiment 6 of the device is designed according to any of the embodiments 1 to 5, wherein the device includes a further component, wherein the sheetlike composite has been brought into contact with the further component, wherein the first component moves in a first direction, wherein the further component moves in a further direction, wherein the further direction differs from the first direction. It is preferable here that the sheetlike composite has been brought into contact at its internal surface with the further component. It is preferable that the further component guides the sheetlike composite. It is preferable that the first direction is opposite to the further direction.
An inventive embodiment 7 of the device is designed according to the embodiment 6, wherein the first component rotates, wherein the first direction is a first direction of rotation, wherein the further component rotates, wherein the further direction is a further direction of rotation.
An inventive embodiment 8 of the device is designed according to the embodiment 7, wherein the first rotating component is an intaglio printing roll.
An inventive embodiment 9 of the device is designed according to any of the embodiments 1 to 8, wherein the first component has been earthed.
An inventive embodiment 10 of the device is designed according to any of the embodiments 1 to 9, wherein the sheetlike composite is characterized by an ignition residue in the range from 0.1 to 75 mg, preferably from 0.2 to 50 mg, most preferably from 0.3 to 30 mg.
An inventive embodiment 11 of the device is designed according to any of the embodiments 1 to 10, wherein the sheetlike composite further includes a polymeric external layer on one side of the carrier layer, wherein the said side faces towards the external surface, wherein the thickness of the polymeric external layer is in the range from 1 to 30 μm, preferably from 2 to 25 μm, more preferably from 3 to 20 μm.
An inventive embodiment 12 of the device is designed according to any of the embodiments 1 to 10, wherein the external surface is a surface of the carrier layer.
An inventive embodiment 13 of the device is designed according to any of the embodiments 1 to 12, wherein the polymeric internal layer includes from 10 to 90% by weight, based on the total weight of the polymeric internal layer, of a polymer produced by means of a metallocene catalyst. A preferred polymer polymerized by means of a metallocene catalyst is an mPE.
An inventive embodiment 14 of the device is designed according to any of the embodiments 1 to 13, wherein the polymeric internal layer includes a polymer blend, wherein the polymer blend includes from 10 to 90% by weight of an mPE and at least 10% by weight of a further polymer, based in each case on the total weight of the polymer blend.
An inventive embodiment 15 of the device is designed according to any of the embodiments 1 to 14, wherein the carrier layer includes, preferably consists of, one selected from the group consisting of paperboard, cardboard, and paper, or a combination of at least two thereof.
An inventive embodiment 16 of the device is designed according to any of the embodiments 1 to 15, wherein the carrier layer has at least one hole, wherein the hole has been covered at least by the barrier layer and at least by the polymeric internal layer as hole-covering layers. The hole-covering layers are in each case the layers covering the at least one hole.
An inventive embodiment 17 of the device is designed according to any of the embodiments 1 to 16, wherein the external surface is not included by a covering layer of the carrier layer.
An embodiment 1 of a printed sheetlike composite 2 including, as mutually superposed layers, from an external surface of the printed sheetlike composite to an internal surface of the printed sheetlike composite,
An inventive embodiment 2 of the printed sheetlike composite 2 is designed according to the embodiment 1, wherein the sheetlike composite further includes a polymeric external layer between the colour layer and the carrier layer, wherein the polymeric external layer is characterized by a layer thickness in the range from 1 to 30 μm, preferably from 2 to 25 μm, more preferably from 3 to 20 μm.
An embodiment 1 of a printed sheetlike composite 3 including, as mutually superposed layers, from an external surface of the printed sheetlike composite to an internal surface of the printed sheetlike composite,
An inventive embodiment 2 of the printed sheetlike composite 3 is designed according to the embodiment 1, wherein the printed sheetlike composite is characterized by an ignition residue in the range from 0.1 to 75 mg, preferably from 0.2 to 50 mg, most preferably from 0.3 to 30 mg.
An inventive embodiment 3 of the printed sheetlike composite 2 or 3 is designed according to the respective embodiment 1 or 2, wherein the colour layer includes a first colour layer region and a further colour layer region, wherein the first colour layer region is characterized by an area coverage of at least 50%, preferably of at least 60%, more preferably of at least 70%, more preferably of at least 80%, most preferably of at least 90%, wherein the further colour layer region is characterized by an area coverage in the range from more than 0 up to 15%, preferably from more than 0 up to 13%, more preferably from more than 0 up to 11%, more preferably from more than 0 up to 9%, most preferably from more than 0 up to 5%, wherein the first colour layer region adjoins the further colour layer region. It is preferable that the abovementioned area coverages refer to the same colour.
An inventive embodiment 4 of the printed sheetlike composite 2 or 3 is designed according to any of the respective embodiments 1 to 3, wherein the colour layer is characterized by a number of absent matrix dots in the range from 0 to 100, preferably from 0 to 70, more preferably from 0 to 60, more preferably from 0 to 40, more preferably from 0 to 30, more preferably from 0 to 20, more preferably from 0 to 10, most preferably from 0 to 8, in each case per 100 mm2.
An embodiment 1 of a container precursor at least to some extent including the printed sheetlike composite 1 according to any of the embodiments 1 to 3, or the printed sheetlike composite 2 or 3 according to any of the respective embodiments 1 to 4 makes a contribution to achievement of at least one of the objects of the invention.
An embodiment 1 of a closed container at least to some extent including the printed sheetlike composite 1 according to any of the embodiments 1 to 3, or the printed sheetlike composite 2 or 3 according to any of the respective embodiments 1 to 4, wherein the printed sheetlike composite has been folded at least once, more preferably at least twice, more preferably at least 3 times, more preferably at least 4 times, more preferably at least 5 times, most preferably at least 8 times makes a contribution to achievement of at least one of the objects of the invention.
An embodiment 1 of a use of the device according to any of the embodiments 1 to 17 for printing of the sheetlike composite makes a contribution to achievement of at least one of the objects of the invention. A preferred printing is an intaglio printing.
In an inventive embodiment 2 of the use of the device, the printing takes place directly onto a surface of the carrier layer.
Preferred embodiments of constituents of a category of the invention, in particular of the process, of the printed sheetlike composite, of the container precursor, of the closed container, of the device and of the use are likewise preferred for the eponymous or corresponding constituents of the respective other categories of the invention.
The external surface of the sheetlike composite is the surface which in a container to be produced from the sheetlike composite faces predominantly outwards. Accordingly, the external surface is in direct contact with an environment of the container. The external surface and the internal surface in the sheetlike composite form surfaces opposite to one another in the sheetlike composite.
Unless otherwise stated, the layers in a layer sequence can follow one another indirectly, i.e. with one or at least two intermediate layers, or directly, i.e. without intermediate layer. This is in particular the case with wording wherein there is a layer superposed on another layer. Wording wherein a layer sequence includes a list of layers means that at least the stated layers are present in the stated sequence. This wording does not necessarily mean that these layers follow one another directly. Wording wherein two layers are adjacent to one another means that these two layers follow one another directly, and therefore without intermediate layer.
Material used as carrier layer can be any suitable material which is known to the person skilled in the art for this purpose and which has strength and stiffness sufficient to provide the container with stability to such an extent that the container in essence retains its shape in the presence of its contents. This document also uses the term dimensionally stable to describe a container of this type. In particular, bags and containers made of foils without carrier layer are not dimensionally stable. Preferred materials for the carrier layer are not only several plastics but also plant-based fibre materials, in particular chemical pulps, preferably glued, bleached and/or unbleached chemical pulps, particular preference being given here to paper and paperboard. The weight per unit area of the carrier layer is preferably in the range from 120 to 450 g/m2, particularly preferably in the range from 130 to 400 g/m2 and most preferably in the range from 150 to 380 g/m2. A preferred paperboard generally has a single- or multilayer structure and can have been coated on one or both sides with one or more covering layers. The residual moisture content of a preferred paperboard is moreover less than 20% by weight, preferably from 2 to 15% by weight and particularly preferably from 4 to 10% by weight, based on the total weight of the paperboard. A particularly preferred paperboard has a multilayer structure. It is further preferable that the paperboard has, on the surface facing towards the environment, at least one, but particularly preferably at least two, sublayers of a covering layer known to the person skilled in the art as “paper coating”. The Scott Bond value of a preferred paperboard is moreover in the range from 100 to 360 J/m2, preferably from 120 to 350 J/m2 and particularly preferably from 135 to 310 J/m2. Use of the abovementioned ranges allows provision of a composite from which it is easily possible to fold a highly leakproof container with narrow tolerances. A preferred carrier layer includes on at least one surface, preferably on each of two mutually opposite surfaces, a covering layer. Except where this is expressly excluded, it is preferable that each carrier layer includes a covering layer on each surface. It is preferable that the carrier layer is of one-piece design.
Material used as barrier layer can be any material which is known for this purpose to the person skilled in the art and which exhibits adequate barrier action in particular in relation to oxygen. It is preferable that the barrier layer is selected from
It is preferable that the barrier layer is of one-piece design.
If, according to alternative a., a barrier layer is a plastics barrier layer, this preferably includes at least 70% by weight, particularly at least 80% by weight and most preferably at least 95% by weight, of at least one plastic which is known for this purpose to the person skilled in the art, in particular on account of aroma properties or, respectively, gas-barrier properties that are suitable for packaging containers. Plastics, in particular thermoplastics, that can be used here are N- or O-containing plastics, either as such or else in mixtures of two or more. A melting point of the plastics barrier layer in the range from more than 155 to 300° C., preferably in the range from 160 to 280° C. and particularly preferably in the range from 170 to 270° C. can prove advantageous according to the invention. A preferred electrically insulating barrier layer is a plastics barrier layer.
It is further preferable that the weight per unit area of the plastics barrier layer is in the range from 2 to 120 g/m2, preferably in the range from 3 to 60 g/m2, particularly preferably in the range from 4 to 40 g/m2 and with further preference from 6 to 30 g/m2. It is further preferable that the plastics barrier layer can be obtained from melts, for example via extrusion, in particular layer extrusion. It is further preferable that the plastics barrier layer can be introduced into the sheetlike composite by way of lamination. Preference is given here to incorporation of a foil into the sheetlike composite. According to another embodiment it is also possible to select plastics barrier layers which can be obtained via deposition from a solution or dispersion of plastics.
Suitable polymers are preferably those whose weight-average molar mass, determined by gel permeation chromatography (GPC) using light scattering, is in the range from 3·103 to 1·107 g/mol, preferably in the range from 5·103 to 1·106 g/mol and particularly preferably in the range from 6·103 to 1·105 g/mol. Suitable polymers that in particular can be used are polyamide (PA) or polyethylene vinyl alcohol (EVOH) or a mixture thereof.
Among the polyamides, it is possible to use any of the PAs that appear to a person skilled in the art to be suitable for the inventive use. Particular mention should be made here of PA 6, PA 6.6, PA 6.10, PA 6.12, PA 11 or PA 12 or a mixture of at least two thereof, particular preference being given here to PA 6 and PA 6.6, and further preference being given here to PA 6. PA 6 is obtainable commercially by way of example with the trademark Akulon®, Durethan® and Ultramid®. Other suitable materials are amorphous polyamides such as MXD6, Grivory®, and also Selar® PA. It is further preferable that the density of the PA is in the range from 1.01 to 1.40 g/cm3, preferably in the range from 1.05 to 1.30 g/cm3 and particularly preferably in the range from 1.08 to 1.25 g/cm3. It is further preferable that the viscosity number of the PA is in the range from 130 to 185 ml/g and preferably in the range from 140 to 180 ml/g.
EVOH that can be used is any of the EVOHs that appear to the person skilled in the art to be suitable for the inventive use. Examples here are obtainable commercially inter alia with the trademark EVAL™ from EVAL Europe NV, Belgium in a plurality of different embodiments, examples being the grades EVAL™ F104B and EVAL™ LR171B. Preferred EVOHs have at least one, two, a plurality of, or all of, the following properties:
According to alternative b. the barrier layer is a metal layer. A suitable metal layer is in principle any of the layers using metals which are known to the person skilled in the art and which can provide high impermeability to light and to oxygen. According to a preferred embodiment the metal layer can take the form of a film or of a deposited layer, e.g. after a physical gas-phase deposition process. It is preferable that the metal layer is an uninterrupted layer. According to another preferred embodiment, the thickness of the metal layer is in the range from 3 to 20 μm, preferably in the range from 3.5 to 12 μm and particularly preferably in the range from 4 to 10 μm.
Metals preferably selected are aluminium, iron or copper. A preferred iron layer can be a steel layer, e.g. in the form of a foil. It is further preferable that the metal layer is a layer using aluminium. The aluminium layer can advantageously consist of an aluminium alloy, for example AlFeMn, AlFe1.5Mn, AlFeSi or AlFeSiMn. Purity is usually 97.5% or higher, preferably 98.5% or higher, based in each case on the entire aluminium layer. In a particular embodiment the metal layer consists of an aluminium foil. The extensibility of suitable aluminium foils is more than 1%, preferably more than 1.3% and particularly preferably more than 1.5%, and their tensile strength is more than 30 N/mm2, preferably more than 40 N/mm2 and particularly preferably more than 50 N/mm2. Suitable aluminium foils exhibit a droplet size of more than 3 mm in the pipette test, preferably more than 4 mm and particularly preferably more than 5 mm. Suitable alloys for the production of aluminium layers or aluminium foils are obtainable commercially as EN AW 1200, EN AW 8079 or EN AW 8111 from Hydro Aluminium Deutschland GmbH or Amcor Flexibles Singen GmbH. A preferred electrically conductive barrier layer is a metal barrier layer, particularly preferably an aluminium barrier layer.
When a metal foil is used as barrier layer, there can be an adhesion-promoter layer provided on one or both sides of the metal foil between the metal foil and the closest polymer layer. According to a particular embodiment of the container of the invention, however, there is no adhesion-promoter layer provided on any side of the metal foil between the metal foil and the closest polymer layer.
It is further preferable to select a metal oxide layer as barrier layer according to alternative c. Metal oxide layers that can be used are any of the metal oxide layers that are familiar to the person skilled in the art and that appear suitable for achieving a barrier effect in relation to light, water vapour and/or gas. In particular, preference is given to metal oxide layers based on the abovementioned metals aluminium, iron or copper and also to metal oxide layers based on compounds of titanium or silicon oxide. A metal oxide layer is produced by way of example via deposition of a metal oxide from a vapour onto a plastics layer, for example an oriented polypropylene film. A preferred process for this is physical gas-phase deposition.
According to another preferred embodiment the metal layer or the metal oxide layer can take the form of a layer composite made of one or more plastics layers with a metal layer. This type of layer can be obtained by way of example via vapour deposition of a metal onto a plastics layer, for example an oriented polypropylene film. A preferred process for this is physical gas-phase deposition.
It is preferable that there is a polymer layer located between the carrier layer and the barrier layer. Each polymer layer can comprise further constituents. It is preferable that these polymer layers are introduced or, respectively, applied into the layer sequence in an extrusion process. The further constituents of the polymer layers are preferably constituents which do not adversely affect the behaviour of the polymer melt when applied as layer. The further constituents can by way of example be inorganic compounds, such as metal salts or further plastics, for example further thermoplastics. However, it is also conceivable that the further constituents are fillers or pigments, for example carbon black or metal oxides. Suitable thermoplastics that can be used for the further constituents are in particular those that are easily processable by virtue of good extrusion properties. Materials suitable in this context are polymers obtained via chain polymerization, in particular polyesters or polyolefins, particular preference being given here to cyclic olefin copolymers (COC), and polycyclic olefin copolymers (POC), and in particular polyethylene and polypropylene, and very particular preference being given here to polyethylene. Among the polyethylenes, preference is given to HDPE, MDPE, LDPE, LLDPE, VLDPE and PE, and also to mixtures of at least two thereof. It is also possible to use mixtures of at least two thermoplastics. The melt flow rate (MFR) of suitable polymer layers is in the range from 1 to 25 g/10 min, preferably in the range from 2 to 20 g/10 min and particularly preferably in the range from 2.5 to 15 g/10 min, their density being in the range from 0.890 g/cm3 to 0.980 g/cm3, preferably in the range from 0.895 g/cm3 to 0.975 g/cm3, and more preferably in the range from 0.900 g/cm3 to 0.970 g/cm3. The polymer layers preferably have at least one melting point in the range from 80 to 155° C., with preference in the range from 90 to 145° C. and particularly preferably in the range from 95 to 135° C. A preferred polymer layer is a polyolefin layer, preferably a polyethylene layer or a polypropylene layer or both.
A preferred polyolefin is a polyethylene (PE) or a polypropylene or both. A preferred polyethylene is one selected from the group consisting of an LDPE, an LLDPE, and an HDPE, or a combination of at least two thereof. A particularly preferred PE is an LDPE. Another preferred polyolefin is an m-polyolefin. The melt flow rate (MFR) of suitable polyethylenes is in the range from 1 to 25 g/10 min, preferably in the range from 2 to 20 g/10 min and particularly preferably in the range from 2.5 to 15 g/10 min, their density being in the range from 0.910 g/cm3 to 0.935 g/cm3, preferably in the range from 0.912 g/cm3 to 0.932 g/cm3, and more preferably in the range from 0.915 g/cm3 to 0.930 g/cm3.
m-Polyolefin
An m-polyolefin is a polyolefin produced by means of a metallocene catalyst. A metallocene is an organometallic compound in which there is a central metal atom arranged between two organic ligands, for example cyclopentadienyl ligands. A preferred m-polyolefin is an m-polyethylene (mPE) or an m-polypropylene or both. A preferred mPE is one selected from the group consisting of an mLDPE, an mLLDPE, and an mHDPE, or a combination of at least two thereof.
In a preferred embodiment the polymeric internal layer includes from 10 to 50% by weight, preferably 15 to 45% by weight, more preferably from 20 to 40% by weight, most preferably from 25 to 35% by weight, based in each case on the total weight of the polymeric internal layer, of a polymer produced by means of a metallocene catalyst. In another preferred embodiment the polymeric internal layer includes from 20 to 90% by weight, preferably from 30 to 90% by weight, more preferably from 40 to 90% by weight, more preferably from 50 to 90% by weight, more preferably from 60 to 90% by weight, most preferably from 70 to 85% by weight, based in each case on the total weight of the polymeric internal layer, of a polymer produced by means of a metallocene catalyst.
It is preferable that the polymeric internal layer consists of the polymer blend including an mPE and a further polymer. A preferred further polymer is a PE. In a preferred embodiment the polymer blend includes from 10 to 50% by weight, preferably from 15 to 45% by weight, more preferably from 20 to 40% by weight, most preferably from 25 to 35% by weight, of an mPE and at least 50% by weight, preferably at least 55% by weight, more preferably at least 60% by weight, most preferably at least 65% by weight, of a further polymer, based in each case on the total weight of the polymer blend. In another preferred embodiment the polymer blend includes from 20 to 90% by weight, preferably from 30 to 90% by weight, more preferably from 40 to 90% by weight, more preferably from 50 to 90% by weight, more preferably from 60 to 90% by weight, most preferably from 70 to 85% by weight, of an mPE and at least 10% by weight, preferably at least 15% by weight, of a further polymer, based in each case on the total weight of the polymer blend. The proportions of mPE and of further polymer in the polymer blend here are preferably combined in such a way that the sum of the proportions is 100% by weight. In each case the preferred proportions of mPE and of further polymer in the polymer blend are combined in such a way that the sum of the proportions is not more than 100% by weight. It is preferable that the internal surface of the sheetlike composite is a polymeric-internal-layer surface that faces away from the barrier layer. The internal surface of the sheetlike composite here is the surface which in a container to be produced from the sheetlike composite faces predominantly inwards, i.e. in particular is in direct contact with a food contained in the container.
A preferred m-polyolefin is characterized by at least one first melting point and one second melting point. It is preferable that the m-polyolefin is characterized by a third melting point in addition to the first and the second melting point. A preferred first melting point is in the range from 84 to 108° C., preferably from 89 to 103° C., more preferably from 94 to 98° C. A preferred further melting point is in the range from 100 to 124° C., preferably from 105 to 119° C., more preferably from 110 to 114° C.
There can be an adhesion-promoter layer located between layers of the sheetlike composite which are not immediately adjacent to one another. In particular, there can be an adhesion-promoter layer located between the barrier layer and the polymeric internal layer or the carrier layer and the barrier layer.
Plastics which can be used as adhesion promoters in an adhesion-promoter layer are any of those which, by virtue of functionalization by means of suitable functional groups, are suitable to produce a secure bond via formation of ionic bonds or covalent bonds to a surface of a respective adjacent layer. The materials are preferably functionalized polyolefins obtained via copolymerization of ethylene with acrylic acids such as acrylic acid or methacrylic acid, crotonic acid, acrylates, acrylate derivatives or carboxylic anhydrides containing double bonds, for example maleic anhydride, or at least two thereof. Among these, preference is given to polyethylene-maleic anhydride graft polymers (EMAH), ethylene-acrylic acid copolymers (EAA) or ethylene-methacrylic acid copolymers (EMAA), which are marketed by way of example with the trademarks Bynel® and Nucrel®0609HSA by DuPont or Escor®6000ExCo by ExxonMobil Chemicals.
According to the invention it is preferable that the adhesion between a carrier layer, a polymer layer or a barrier layer and the respective closest layer is at least 0.5 N/15 mm, preferably at least 0.7 N/15 mm and particularly preferably at least 0.8 N/15 mm. In an embodiment of the invention it is preferable that the adhesion between a polymer layer and a carrier layer is at least 0.3 N/15 mm, preferably at least 0.5 N/15 mm and particularly preferably at least 0.7 N/15 mm. It is further preferable that the adhesion between a barrier layer and a polymer layer is at least 0.8 N/15 mm, preferably at least 1.0 N/15 mm and particularly preferably at least 1.4 N/15 mm. In the event that a barrier layer follows a polymer layer indirectly by way of an adhesion-promoter layer it is preferable that the adhesion between the barrier layer and the adhesion-promoter layer is at least 1.8 N/15 mm, preferably at least 2.2 N/15 mm and particularly preferably at least 2.8 N/15 mm. In a particular embodiment the adhesion between the individual layers is so strong that the adhesion test leads to tearing of a carrier layer, the term used in the event of paperboard as carrier layer being paperboard fibre tear.
The first component is designed to receive printing ink into the recesses, also termed cells, and for the transfer of at least a portion of the printing ink from the recesses to the external surface of the sheetlike composite. To this end, it is preferable that the external surface is pressed onto the first component surface. A preferred first component is a printing plate or a printing roll or both. A preferred printing plate is an intaglio printing plate. A preferred printing roll is an intaglio printing roll. A preferred first component surface is flat or takes the form of the curved surface of a cylinder, or both. A preferred further component is a further roll. A preferred further roll is a counterpressure roll. A preferred counterpressure roll is an impression roll. It is preferable that the impression roll consists of a hard material such as wood or metal covered by a rubber layer.
A preferred composition is a solution or a suspension or both. Another preferred composition is a printing ink. A preferred printing ink is a printing ink for intaglio printing. A preferred colourant is a pigment. It is preferable that the composition in the recesses in each case includes a convex surface.
A preferred contacting is an applying of pressure. It is preferable that the contacting is a printing. In this, the sheetlike composite is preferably passed through a gap between the intaglio printing roll and the impression roll.
A preferred covering layer is a “paper-coating layer”. In papermaking a “paper-coating layer” is an covering layer which includes inorganic solid particles, preferably pigments and additives. It is preferable that the “paper-coating layer” is applied in the form of liquid phase, preferably in the form of suspension or dispersion, to a surface of a paper- or paperboard-containing layer. A preferred dispersion is an aqueous dispersion. A preferred suspension is an aqueous suspension. Another preferred liquid phase includes inorganic solid particles, preferably pigments; a binder; and additives. A preferred pigment is selected from the group consisting of calcium carbonate, kaolin, talcum, silicate, a plastics pigment and titanium dioxide. A preferred kaolin is a calcined kaolin. A preferred calcium carbonate is one selected from the group consisting of marble, chalk and a precipitated calcium carbonate (PCC) or a combination of at least two thereof. A preferred silicate is a phyllosilicate. A preferred plastics pigment is spherical, preferably hollow-spherical. A preferred binder is one selected from the group consisting of styrene-butadiene, acrylate, acrylonitrile, a starch and a polyvinyl alcohol or a combination of at least two thereof, preference being given here to acrylate. A preferred starch is one selected from the group consisting of cationically modified, anionically modified and fragmented or a combination of at least two thereof. A preferred additive is one selected from the group consisting of a rheology modifier, a shading dye, an optical brightener, a carrier for an optical brightener, a flocculating agent, a deaerating agent and a surface-energy modifier or a combination of at least two thereof. A preferred deaerating agent is a deaerating agent which is used for coloured coating slips and which is preferably based on silicone or on fatty acid or on both. A preferred surface-energy modifier is a surfactant.
A container precursor is a closed-container precursor produced during the production of a closed container. The container precursor here includes the sheetlike composite in cut-to-size form. The sheetlike composite here can be unfolded or folded. A preferred container precursor has been cut to size and is designed for the production of a single closed container. Another term used for a preferred container precursor which has been cut to size and is designed for the production of a single closed container is also referred to a jacket or a sleeve. The jacket or sleeve here includes the folded sheetlike composite. The jacket or sleeve moreover includes a longitudinal seam and is open in a top region and in a base region. The term tube is often used for a typical container precursor which has been cut to size and is designed for the production of a plurality of closed containers.
Another preferred container precursor is open, preferably in a top region or in a top region, particularly preferably in both. A preferred container precursor takes the form of a jacket or of a tube or both. Another preferred container precursor includes the printed sheetlike composite in a manner such that the printed sheetlike composite has been folded at least once, preferably at least twice, more preferably at least 3 times, most preferably at least 4 times. A preferred container precursor is of a one-piece design. It is particularly preferable that a base region of the container precursor is of a one-piece design with a lateral region of the container precursor.
The closed container of the invention can have a plurality of different shapes, but preference is given to a structure that is in essence a rectangular parallelepiped. It is moreover possible that the entire area of the container is composed of a sheetlike composite, or that the container has a two- or multipart structure. In the case of a multipart structure it is conceivable that other materials are also used alongside the sheetlike composite, an example being plastic, which in particular can be used in the top or base regions of the container. However, it is preferable here that at least 50%, particularly at least 70% and more preferably at least 90%, of the area of the container is composed of the sheetlike composite. The container can moreover comprise a device for the discharge of the contents. This can by way of example be formed from plastic and applied to the external side of the container. It is also conceivable that this device has been integrated into the container via “direct injection moulding”. According to a preferred embodiment the container of the invention has at least one folded edge, preferably from 4 to 22, or even more folded edges, particularly preferably from 7 to 12 folded edges. For the purposes of the present invention the expression folded edge applies to regions produced when an area is folded. Examples of folded edges that may be mentioned are the longitudinal regions where two respective wall areas of the container meet. The container walls in the container are preferably the areas of the container, surrounded by the folded edges. It is preferable that the closed container includes no base that is not of single-piece design with the sheetlike composite or no lid that is not of single-piece design with the sheetlike composite, or both.
A preferred closed container of the invention includes a food. Materials that can be regarded as foods are any of the solid or liquid foods known to the person skilled in the art for human consumption, and also those for consumption by animals. Preferred foods are liquid above 5° C., examples being dairy products, soups, sauces, and non-carbonated drinks There are various methods for filling the container or the container precursor. A first possibility is that the food and the container or the container precursor are separately, before the filling process, sterilized to the greatest possible extent via suitable measures such as treatment of the container or of the container precursor with H2O2, UV radiation or other suitable high-energy radiation, plasma or a combination of at least two thereof, and also heating of the food, and that the container or the container precursor is then filled. This filling method is often termed “aseptic filling”, and is preferred according to the invention. In another method that is widely used, in addition to or else instead of aseptic filling, the container or container precursor filled with food is heated to reduce the number of germs. This is preferably achieved via pasteurization or autoclaving. In this procedure it is also possible to use less sterile foods and containers or container precursors.
In order to provide easier opening of the closed container of the invention, a carrier layer can comprise at least one hole. In a particular embodiment the hole has been covered at least by a barrier layer, and preferably a polymer layer, as hole-covering layers. There can moreover be one or more further layers, in particular adhesion-promoter layers, provided between the abovementioned layers. It is preferable here that the hole-covering layers have been joined to one another at least to some extent, preferably at least 30%, with preference at least 70% and with particular preference at least 90% of the area formed by the hole. According to a particular embodiment it is preferable that the hole penetrates through the entire sheetlike composite and is covered by a closure or opening device that seals the hole. In connection with a preferred embodiment the hole provided in the carrier layer can have any shape that is known to the person skilled in the art and is suitable for various closures, drinking straws or opening aids. Opening of a closed container is mostly achieved by destroying, at least to some extent, the hole-covering layers covering the hole. This destruction can be achieved via cutting, pressing into the container or pulling out of the container. The destruction can be achieved via an openable closure joined to the container and arranged in the region of the hole, mostly above the hole, or via a drinking straw which is forced through the hole-covering layers covering the hole.
According to another preferred embodiment a carrier layer of the sheetlike composite has a plurality of holes in the form of a perforation, where the individual holes have been covered at least by a barrier layer, and preferably by a polymer layer, as hole-covering layers. A container produced from this type of composite can then be opened by tearing along the perforation. Holes of these types for perforations are preferably produced by means of a laser. It is particularly preferable to use laser beams when a metal foil or a metallized foil is used as barrier layer. It is moreover possible to introduce the perforation by using mechanical perforation tools, mostly comprising blades.
According to another preferred embodiment the sheetlike composite is subjected to heat treatment, at least in the region of the at least one hole. Where there is a plurality of holes present in the form of a perforation in the carrier layer it is in particular preferable that this heat treatment is also carried out around the periphery of the hole. The heat treatment can be achieved via radiation, via hot gas, via thermal contact with a solid material, via mechanical oscillations, preferably via ultrasound, or via a combination of at least two of these measures. It is particularly preferable that the heat treatment is achieved via irradiation, preferably electromagnetic radiation and particularly preferably electromagnetic induction, or else via hot gas. The respective optimal operating parameters to be selected are known to the person of average skill in the art.
The following test methods were used for the purposes of the invention. Unless otherwise stated the measurements were made at ambient temperature 25° C., ambient air pressure 100 kPa (0.986 atm) and relative humidity 50%.
The MFR value is measured in accordance with the standard ISO 1133 (unless otherwise stated at 190° C. with 2.16 kg).
Density is measured in accordance with the standard ISO 1183-1.
Melting point is determined according to the DSC method of ISO 11357-1 and -5. The equipment is calibrated in accordance with the manufacturer's instructions with reference to the following measurements:
The viscosity number of PA is measured in accordance with the standard ISO 307 in 95% sulphuric acid.
Oxygen permeation rate is determined in accordance with the standard ISO 14663-2 Annex C at 20° C. and 65% relative humidity.
Paperboard moisture content is measured in accordance with the standard ISO 287:2009.
Adhesion between two adjacent layers is determined by fixing these onto 90° peel test equipment, for example a “German rotating wheel fixture” from Instron, on a rotating roll which rotates at 40 mm/min during the measurement. The samples were cut to size in advance, into strips of width 15 mm. At one side of the sample the sublayers are separated from one another, and the separated end is clamped into a vertically upwards oriented tensile apparatus. The tensile apparatus has attached measurement equipment for determining the tensile force. During the rotation of the roll, the force required to separate the sublayers from one another is measured. This force corresponds to the adhesion between the layers, and is stated in N/15 mm. The separation of the individual layers can be achieved by way of example mechanically, or via a specific pretreatment, for example via softening of the sample for 3 min in 30% acetic acid at 60° C.
Molecular weight distribution is measured by gel permeation chromatography, using light scattering: ISO 16014-3/-5.
Five regions of the printed container or laminate measuring 10 mm-10 mm are studied under an optical microscope. An unprinted dot of the printed matrix corresponds here to an absent matrix dot. The absent matrix dots are counted for each of the five regions. The arithmetic average (average value) from the five measurements is the “absent matrix dots” value.
The area coverage is a measure of the extent of cover in a printed area as perceived by a standard observer. Area coverage can be calculated by the Murray-Davies formula. All of the area coverage values in this document were measured with the aid of a spectrophotometer (SpectroEye™) from X-Rite (CH-8105 Regensdorf).
The measurement is made in transverse direction in the middle of the web of composite material at intervals of 1 cm, using a Fluke 280 combined with a Fluke 80 k-6 high-voltage probe from Fluke Deutschland GmbH, Glottertal, Germany. The measurement is moreover made on the external surface of the laminate in the middle between the electrode which applies the electrical charges to the sheetlike composite and the first component which prints the sheetlike composite. The first component here is earthed.
In accordance with the standard DIN EN ISO 186 (differing from DIN EN 20 287), for determination of ignition loss sample sections measuring 50 mm-50 mm (0.0025 m2) are produced from the packaging containers or packaging container precursors or laminates to be tested.
The following steps are then carried out:
A sample measuring about 2.5 to 3.0 cm·1.0 to 1.5 cm is taken from the composite material (laminate, sheetlike composite) to be studied. The longitudinal side of the sample here is perpendicular to the direction of running of the extrusion process and to the fibre direction of the paperboard. The sample is secured in a metal clamp which forms a smooth surface. The sample should not project by more than 2-3 mm. The metal clamp is secured before the cut is made. In order that the cut obtained, in particular of the paperboard fibre, is clean, the sample portion protruding from the metal clamp is iced with cold spray. This is then removed by means of a disposable blade. The pressure exerted by the metal clamp on the sample is then reduced so that the sample can be moved out of the metal clamp by about 3-4 mm. It is then again secured. For study under the optical microscope, the sample in the sample holder is placed on the object stage of the optical microscope under one of the objectives. The appropriate objective should be selected as a function of the layer thickness of the region to be studied. Precise centring is achieved during study under the microscope. Side illumination (swan necks) is used in most cases. If necessary, the epi-illumination system of the optical microscope is used in addition or instead. Once focusing and illumination of the sample have been optimized, the individual layers of the composite are discernible. An Olympus camera with appropriate image-processing software from Analysis is used for documentation and measurements. The thickness of the polymeric external layer is stated in absolute terms in micrometres (μm).
Optical microscope; Nikon Eclipse E800
Objective; ×2.5; ×5; ×10; ×20; ×50 magnification
Illumination: swan necks
Software: analySIS
Disposable blades; from Leica (Microtome Blades)
Sample holder: metal clamp
Cold spray
Cut-resistant gloves
The invention is described in more detail below via Examples and drawings, wherein the Examples and drawings do not imply any restriction of the invention. The drawings are moreover diagrammatic and not true to scale.
A commercially available uncoated paperboard (NaturaD UC 200 mN; Stora Enso AB; Stockholm, Sweden) is treated in the following steps:
Laminates with the following layer structure were used for Inventive Examples 1 to 15 listed below and for Comparative Examples 1 to 7. The said laminates were obtained in the above steps 1. to 4.
Comparative Examples 1 to 7 are produced without use of an electrode to charge either the impression roll or the laminate in the above step 3. of the production of the laminate.
Inventive Examples 1 to 7 are produced by using an electrode in step 3. of the production of the laminate to transfer electrical charges to the impression roll and from this to the internal surface of the laminate. No direct charging of laminate on its external surface takes place.
Inventive Examples 8 to 15 are produced by using the electrode in step 3. of the production of the laminate to apply electrical charges to the external surface of the laminate as shown in
In the “Matrix” column in each of the Tables 1 to 3 the matrix used for the intaglio printing process is characterized via the number of matrix cells per unit of length in dots per centimetre. The accuracy of the layer thicknesses stated in the Tables 1 to 3 for the polymeric external layers is dependent on the measurement method and in each case is ±1.5 μm.
In the drawings:
| Number | Date | Country | Kind |
|---|---|---|---|
| 10 2015 010 406.3 | Aug 2015 | DE | national |
| 10 2016 209 349.5 | May 2016 | DE | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/EP2016/069246 | 8/12/2016 | WO | 00 |
