Sealing multilayer film and hermetically sealable container made therewith

The present invention relates to a sealing layer of at least two layers of substantially thermoplastic plastics and a packaging material containing this sealing layer as a component. The multilayered sealing layer is characterized in that at least one layer of this sealing layer has a composition which is lower viscosity at usual sealing temperatures that of the layer of the sealing layer pointing towards the product. The multilayered sealant layer of the invention is characterized by improved sealing properties, in particular by a combination of high seal seam strength immediately after sealing and rapid hermetic sealability without the formation of needles in the seal seam. As a result, very high processing speeds can be achieved. The invention also includes packaging materials containing such a sealing layer. The invention also relates to the use of the multilayered sealing layer and the packaging materials containing them for the production of packaging materials and the use of these packaging materials for the packaging of foodstuffs and other goods.

Many goods require protection from the ambient air or the surrounding atmosphere for transportation and / or storage. They must therefore be packed in a way that is suitable to exclude all or certain components of the ambient atmosphere as completely as possible.

Such packages are often made by heat sealing one or more packaging materials into a package, such as a bag or lid container. In this case, the packaging material is sealed by fusing the sealing layer, in the example of the bag against itself or in the case of a lid package against the sealing layer of another packaging material. The result is a seal closing the packaging. The state of the art in packaging using plastic-containing packaging materials is approximately in <i>Ahlhaus, packaging with plastics, Hanser Verlag, Munich, 1997,</i> shown. Special constructions of packaging materials are approximately in<i>Bakker, The Wiley Encyclopaedia of Packaging Technology, John Wiley and Sons, New York, 1986,</i> or for slides in <i>Nentwig, plastic films, Hanser Verlag, Munich, 1994,</i> resigned. It also describes the functionalities of typical packaging machines.

In many cases, very high demands are placed on the sealed seam. Thus, the sealed seam must be able to absorb high mechanical loads due to contents, transport or other influences. This is true in many cases immediately after sealing with even hotter seal. For example, in so-called vertical tubular bag machines, due to time constraints, the contents are still introduced into the shaped tube when the transverse sealing tool is closed. When the sealing jaws are opened, the entire product weight is loaded on the sealed seam, which has not yet cooled down, thereby exposing it to tensile stress. In other cases, even without external load alone, the elastic resilience of the packaging material, for example when sealing a fold or in the area of ​​the envelope of the packaging material, can lead to a similar load on the still-warm sealed seam. Too little cohesion of the sealed seam in such cases causes the seam to rise and thus the package fails. The seam strength in the hot state immediately after sealing is commonly referred to as a hottack. A high hottack is an important prerequisite for high packing speeds in cases such as the one described above.

In addition, the sealed seam must apply a firm seal when re-cooled, ie it must be able to absorb high loads in this state, to which the packaging may be exposed during transport or storage, without mechanical failure. Such a tight seal must be achieved as an additional condition for an efficient, ie fast and error-free packaging process with the shortest possible sealing times.

On the other hand, the sealing seam must be tightly sealed with the shortest possible sealing times. If needles between the inside and the outside of the pack, it comes to an intrusion of the surrounding atmosphere and thus possibly to a damage to the medium. Here, in particular, the sealing of wrinkles is critical. So can the package targeted, such as in the form of a longitudinal fold on the side of a bag or at the intersection of longitudinal and transverse seam, or Unintentionally with bad guidance in the machine wrinkles contain, which reach into the sealing seam. For a tight seal of such a fold the sealing layer must be quickly and effectively deformed during the sealing process to completely fill the area around and in the fold, so that it along the sealing seam in the fold area to a continuous contact of the inner surfaces of the sealing layer or the seal layers comes. If achieving a tight seal requires too long sealing times, the processing speed of the film on the packaging machine is reduced again.

The abovementioned short sealing times can be achieved, in particular, by achieving the required properties, such as high seal strength, high hottock and hermetically sealed seal at low temperatures. In this way, at a given temperature of the sealing tool - in many cases, this is due to the temperature resistance of the carrier or Substrate of the packaging material limited - in a shorter time to achieve the above requirements sufficiently high temperature in the sealed seam can be achieved.

The execution of sealing layers in packaging materials according to the prior art is shown below. For all further explanations the following agreements apply.<ul id="ul0001" list-style="bullet"><li>Unless otherwise indicated, abbreviations for plastics according to DIN 7728 or ISO 1043-1987 (E) are used to describe the polymers contained in the individual layers.</li><li>In multilayer constructions, the sequence of layers is represented by a stringing together of the abbreviations of the polymers of the corresponding layers or of otherwise explained symbols, separated by double slashes. The side of the seal layer is always right. In this case, only a part of the total, the construction constituting layer sequence can be specified. In these cases also the side of the sealing layer is always indicated on the right and unlisted layers or combinations of layers by three points,. Similar polymers can be distinguished from each other by a numbering, for example in the form PE-LD-1 // PE-LD-2 // PE-LD-3. Blends of different polymers are identified by the + sign and the summary of the components in parentheses, (). If necessary, additional information on the percentage composition can be made here. Unless otherwise indicated, such instances are always by weight based on the total weight of the mixture. For example, the expression ... // PA // EVOH //...// (PE-LD-1 + PE-LLD) // d describes a structure with an unspecified outer layer or outer layer sequence, followed by a layer consisting essentially of polyamide, followed by a layer consisting essentially of ethylene / vinyl alcohol copolymer (EVOH), followed by an unspecified layer or layer sequence, followed by a layer, comprising a mixture of a number 1 low density polyethylene (PE-LD-1) and an ethylene / α-olefin copolymer (PE-LLD), as well as one to be specified with d, on the sealing side following layer.</li><li>The specification of melting points in the following refers to the value determined according to ASTM 3418 with differential scanning calorimetry analysis (DSC).</li><li>The specification of melt flow rates refers in the following to the value determined according to DIN ISO 1133. In addition, the measuring condition in the form of temperature and the mass, for example, condition D in DIN ISO 1133 with a temperature of 190 ° C and a mass of 2.16 kg, specified.</li><li>The density of the raw materials refers to the measuring method according to ISO 1183 (A).</li></ul>

A measuring method for the property Hottack is given in connection with the examples according to the invention. Qualitatively, the measurement is made in such a way that two sections of packaging material are brought into contact with a defined pressure at a certain temperature and for a given time and then, while the sealing seam is still hot, being pulled apart. Of particular importance here is whether and at what level a time delay between the detachment of the sealing tool and the application of force is allowed. It is possible to measure the maximum force which can be absorbed when pulling apart from the packaging material or, if a force is specified, the resulting deformation of the sealed seam. Basically, a distinction must be made between the hottack force as the force absorbed by the seal seam after sealing without failure and the hottack temperature as the temperature range in which a minimum level of hottack force can be achieved under given seal conditions.

The partial steps taking place during a sealing process are in <i>Meka and Stehling, Heat Sealing of Semicrystalline Polymer Films. II. Effect of Melting Distribution on Heat-Sealing Behavior of Polyolefins, Journal of Applied Polymer Science, Vol. 51, pp. 105-119 (1994),</i> modeled. Thus, first by melting and pressure wetting in the sealed seam. In the further course, chain segments of the polymers diffuse from both sides of the sealed seam into the respective opposite side, thus creating molecular entanglements across the seam. After removal of the sealing tool, the seam cools, and in the case of semicrystalline materials crystallites also form over the seam. If the sealing seam is mechanically stressed immediately after removal of the sealing tool, then the polymers of the sealed seam must have a sufficiently high melt strength in order to be able to absorb this stress.

With structures of sealing layers in packaging materials according to the prior art, both a high hottock and a good needle seal can not be achieved simultaneously.

A high hottack force can be achieved with seal layers by choosing the polymer. Copolymers of ethylene and acrylic acids (E / AA, E / MAA) enable high hottack forces and broad hottack temperature ranges due to the hydrogen bonds between the molecules, which are also effective at high temperatures. This is even more true for ionomers, neutralized acid copolymers containing metal ions because of the ionic binding forces. However, the use of acid copolymers and ionomers is disadvantageous in that they are in turn not compatible with polyethylene-based polymers at higher acid contents and / or degrees of neutralization, which make the said properties possible. This makes it impossible to use the sealing layer for sealing with a further polyethylene-based sealing layer, for example in a lid package, because of the low sealing seam strength which can be achieved in this way. In addition, such a designed packaging can not be used materially again.

In nonpolar sealing media such as low and high density polyethylene (PE-LD, PE-HD), copolymers of ethylene and α-olefins (PE-LLD), copolymers of ethylene and propylene (E / P) or polypropylene (PP) can be higher hottack experience with a reduced MFR, ie achieve with longer-chain polymers and lower Langkettenverzweigung. In the case of PE-LLD, types prepared using metallocene catalysts may be referred to as mPE-LLD in the following and those having a narrower molecular weight distribution and a more uniform distribution as compared to conventional Ziegler-Natta type catalysts Comonomeranteils on the molecules of different lengths, the Hottack force significantly improve. An increase in density causes only a small change in the hottack force in all cases, but the temperature range is shifted to higher values.

Although copolymers of ethylene and vinyl acetate (E / VA) or ethylene and unsaturated esters such as butyl acrylate or ethyl acrylate (E / BA, E / EA) achieve lower sealing temperatures with increasing comonomer content, the Hottack force also decreases.

To achieve good cannula tightness, polymers of low melting point and high MFR, ie low viscosity, are commonly used. In this way, even at low sealing temperatures, the polymer of the sealing layer can flow into and thus close off irregularly shaped portions of the sealing seam, such as in the area of ​​folds.

The requirement for a high seal strength with short sealing times can also be met by specific choice of the or the polymers forming the sealing layer. Thus, it is possible to achieve a good seal seam strength with polymers which themselves have high tear resistance. Such polymers are in particular copolymers of ethylene and α-olefins (PE-LLD) in the range of higher densities, ie with densities above about 910 g / cm³, However, this does not provide comparably short sealing times, such as using ethylene copolymers such as E / VA, E / AA, E / MAA or the like. The said copolymers of ethylene and α-olefins can be blended with branched polymers such as PE-LD for easier processability at approximately constant seam strength. In this way, the seal-initiating temperature can be shifted to lower values ​​if necessary.

If, under given sealing conditions, it is possible to achieve a needle-free seal in the seam, then the seal seam strength which is optimal for the given material combination is necessarily achieved. With regard to the packing speed, therefore, the criterion of a needle-free seal with short sealing times also includes the requirement for an early start of the seal in the sense of achieving the maximum seal strength with short sealing times. High seal strength is a requirement to be met in addition to the needleless seal.

The prior art is also the mixture of the abovementioned polymers and / or a multilayered embodiment of the sealing layer. Thus, the above-mentioned substances can be arranged for cost optimization in such a way that the lying on the inside of the film, the product facing layer is characterized by a particularly early beginning of the seal and the film center adjoining layer, although only at higher temperatures melts, but is cheaper. Optionally, substances produced as adhesion-promoting layers are also produced on the basis of the abovementioned polymers, for example substances modified by grafting with anhydride. Examples of such multilayer constructions are the layer sequences PE-LD // E / VA or PE-LD // E / AA // ionomer.

EP 764679 A1 describes a laminatable sealing layer with a number n of different layers, wherein, viewed from the sealing side, in each layer of the crystalline melting point of the polymer or in polymer blends of that mixing component, which requires the highest enthalpy of fusion, is always higher. The advantage of this design lies in the low sealing temperature and at the same time high seal strength. Examples of such structures are two- and three-layer composites such as PE-LLD // mPE-LLD or PE-LD // (PE-LD + PE-LLD) // (mPE-LLD + PE-LD). These films should have a good hottack, the cannula density of such structures is not mentioned.

Important for a good machinability of packaging materials with such sealing media is also the lubricity. It is improved by additives for the aforementioned polymers of the prior art. For this purpose, anti-blocking agents in the form of solid particles are used, which partially protrude from the outside of the film and thus reduce the effective contact area with the adjacent medium. Examples are silica, calcium carbonate, magnesium silicate, aluminum silicate, calcium phosphate, talc and the like. Silicon dioxide is preferably used. Effective amounts are in the range of 0.1 to 2% by weight. The average particle size is between 1 and 10 microns, in which case particles with a spherical shape are particularly suitable. In multilayer constructions, these particles are preferably used only in the outer layer.

Other additives which improve the lubricity of the film, also in cooperation with said solid particles, are the higher aliphatic acid amides commonly referred to as lubricants, higher aliphatic acid esters, waxes, metal soaps and polydimethylsiloxanes. The effective amount of lubricant is in the range of 0.01 to 3% by weight, preferably 0.02 to 1% by weight. An aliphatic acid amide commonly used for polyolefins is erucic acid amide. The materials mentioned are always limited in the polymer receptive and therefore store after processing on the surfaces. In this way, a lubricious film is formed there.

In summary, the sealing layer for a good hottack should thus have a high and for a good cannula seal a low melt strength. Both objectives can not be achieved with known single-layer or multi-layer sealing layers according to the prior art. The packaging speeds on typical packaging systems such as horizontal and in particular vertical tubular bag machines are therefore limited in many cases either by an insufficient Hottack or too low a cannula seal.

The object was to provide a sealing medium for packaging materials, which allows both a high hottack and a hermetically sealed seal with short sealing times and thus allows higher packing speeds in the composite of a packaging material containing this sealing medium. In addition, the sealing layer should have a sufficiently high sealing seam strength and, in the sense of a combination with another sealing layer in a packaging and in the sense of a material recycling of the packing, be compatible with common polyolefinic sealing media and thus be sealable and miscible with polyethylene.

According to the invention, this was achieved by providing a multilayer, asymmetrical layer sequence (I) which can be used as a sealing layer in conjunction with a substrate, with a layer (b) on the outer side facing the seal, characterized in that<ul id="ul0002" list-style="none"><li>for the total material composition forming the layer sequence (I) a melt flow rate MFR of at least 0.1 g / 10 min, measured according to DIN ISO 1133 at 190 ° C and 2.16 kg, is measurable,</li><li>the layer sequence (I) one or more layers (i₁), (i₂), etc., having a material composition each having a higher melt flow rate MFR, measured according to DIN ISO 1133 at 190 ° C and 2.16 kg, than the material composition forming the layer (b),</li><li>the sum of the basis weights of each of the layers (i₁), (i₂), etc., at least 40%, based on the basis weight of the entire layer sequence (I).</li></ul>

In addition to the layers (b) and (i₁), (i₂), etc., the layer sequence (I) according to the invention may contain further layers.

The layer sequence (I) according to the invention preferably comprises polymers or mixtures of polymers from the group comprising copolymers of ethylene and vinyl acetate (E / VA), more preferably having a vinyl acetate content, based on the total weight of the polymer, of not more than 20%, Copolymers of ethylene and unsaturated esters such as butyl acrylate or ethyl acrylate (E / BA or E / EA) Copolymers of ethylene and unsaturated carboxylic acids (E / AA, E / MAA) more preferably containing the carboxylic acid comonomer, based on the total weight of the polymer, not exceeding 15%, more preferably not more than 8%, Salts of the copolymers of ethylene and unsaturated carboxylic acids, especially E / MAA, (Ionomers), more preferably containing the carboxylic acid comonomer, based on the total weight of the ionomer, not exceeding 15%, more preferably not more than 10%, Low density polyethylene (PE-LD), more preferably at a density of at least 0.91 g / cm³ and at most 0.935 g / cm³, High density polyethylene (PE-HD), copolymers (PE-LLD) of ethylene and α-olefins having at least 3 C atoms, for example, butene, hexene, octene, 4-methyl-1-pentene. The copolymers (PE-LLD) of ethylene and α-olefins can be prepared with conventional catalysts or with metallocene catalysts. Particularly preferred are copolymers (PE-LLD) of ethylene and α-olefins having a density of at least 0.90 g / cm³ and at most 0.94 g / cm³,

The layer (b) preferably comprises copolymers (PE-LLD) of ethylene and α-olefins, low-density polyethylene (PE-LD) and copolymers of ethylene and vinyl acetate (E / VA) of the polymers mentioned. Based on the total weight of the layer (b), a content of 50% to 100% PE-LLD is particularly preferred. In a preferred embodiment, the PE-LLD used is prepared with metallocene catalysts and is characterized by a crystallite melting point of at most 110 ° C and a ratio of the mass-number average molecular weight (M_W/ M_N) of at most 3.

The polymers found in the layer sequence (I) preferably have a melt flow rate, measured according to DIN ISO 1133 at 190 ° C. and a contact mass of 2.16 kg, of at least 0.1 g / 10 min and at most 15 g / 10 min, in a particularly preferred form at least 0.5 g / 10 min and at most 8 g / 10 min. In this case, the layer (b) of the multilayered layer sequence (I) according to the invention contains a composition having a melt flow rate, measured at 190 ° C. and a mass of 2.16 kg, of at least 0.1 g / 10 min and at most 3 g / 10 min , more preferably at least 0.5 g / 10 min and at most 2 g / 10 min, the layers (i₁, i₂, etc.) each having a composition having a melt flow rate, measured at 190 ° C and a mass of 2.16 kg, of at least twice, preferably at least three times and more preferably at least four times the melt flow rate of the layer (b), forming composition.

The sum of the basis weights of each layer (i₁), (i₂), etc., whose material composition has a higher melt flow rate MFR, measured according to DIN ISO 1133 at 190 ° C. and 2.16 kg, than the material layer forming the outer side of the seal (b) is, based on the basis weight of the entire layer sequence ( I), preferably at least 60%, in a still more preferred embodiment at least 70%.

The layer (b) of the multilayered layer sequence (I) according to the invention preferably has a thickness of at most 50 μm, in an even more suitable form of at most 30 μm and even more preferably a maximum of 20 μm. Conveniently, thicknesses of the layer (b) of at least 5 microns, preferably at least 10 microns.

The multi-layer layer sequence (I) according to the invention preferably has, in addition to the layer (b) and the layers (i₁, i₂, etc.) no further layers. In a particularly preferred form, (I) has the structure (i₂) // (i₁) // (b), again in a particularly preferred form the structure (i₁) // (b).

A particular possible embodiment of the layer sequence (I) is the structure (i₁) // (b), where the layers (i₁) and (b) differ essentially only by the melt flow rate.

All or individual layers of the layer sequence (I) can additionally be provided with additives which improve the functionality of the film. Examples are known as antiblocking solid inorganic particles that emerge from the outer surface of the sealant layer and thus improve the sliding behavior of the film. Suitable for this purpose are silicon oxide, calcium carbonate, magnesium silicate, aluminum silicate, calcium phosphate, talc and the like. Silica is preferably used. Effective amounts are in the range of 0.1 to 2 wt .-%, preferably 0.1 to 0.8 wt .-%. The mean particle size is between 1 and 10 .mu.m, preferably 2 and 5 .mu.m, in which case particles with a spherical shape are particularly suitable. Preferably, these particles are used only in the position (b).

Other additives which improve the lubricity of the film, also in cooperation with said solid particles, are the higher aliphatic acid amides commonly referred to as lubricants, higher aliphatic acid esters, waxes, metal soaps and polydimethylsiloxanes. The effective amount of lubricant is in the range of 0.01 to 3 wt%, preferably 0.02 to 1 wt%. Particularly suitable is the addition of higher aliphatic acid amides in the range of 0.01 to 0.25 wt .-%. An aliphatic acid amide suitable in particular for the abovementioned polymers used in the layer sequence (I) is erucic acid amide.

The layer sequence (I) according to the invention can be dyed by adding dyes.

With the multilayered sealing layer according to the invention, it is possible to provide a sealing medium that can be integrated into a packaging material, which is not only distinguished by a good hottack, but surprisingly additionally by a high level of needle sealing. A packaging material containing this sealing layer enables packaging machines of conventional design to have unexpectedly high packing speeds with a low proportion of leaky or poorly sealed packages.

Another object of the invention is therefore a packaging material containing the multilayer sealing layer of the invention and the use of this packaging material for the packaging of foods and stimulants, medical products and products of any kind, which are packaged with a modified atmosphere or in the presence of moisture and / or oxygen are ruinous.

<b>manufacturing</b>

The sealing layer according to the invention and the packaging material containing it can be produced on conventional systems for the production of multilayer composites. The packaging material containing them may in particular be a composite film with a substrate of paper, aluminum, cellophane, polypropylene, polyalkylene terephthalate, polyamide, polycarbonate, polyvinyl alcohol, EVOH, polystyrene or combinations thereof, wherein the thermoplastics may be stretched or unstretched.

If the packaging material is a plastic film, it is possible to coextrude all or part of the layers of the film together as a blown film or as a flat film, ie to combine the polymers of these layers as melt streams and to flow in molten form through a common nozzle. In this way, both the multilayer sealing layer according to the invention can be finished as well as a film composite according to the invention, which contains this multilayered sealing layer as a component.

The multilayer sealing layer according to the invention can also be applied to a prefabricated carrier web by extrusion coating, that is to say the application of the sealing layer in the molten state, and in this way form the packaging material according to the invention with the carrier web. In these cases, the carrier web may consist of plastics such as the abovementioned polymers, metals, cardboard, paper, cardboard, textiles, nonwovens, woven fabrics or composites of the abovementioned substances.

The multilayered sealing layer according to the invention can also be produced by extrusion lamination, that is to say the application of one or more molten thermoplastic polymer layers between two layer sequences of the packaging material according to the invention. In this case, the layers introduced as a melt into the composite can form part of the multilayered sealing layer according to the invention. In any case, the sequence of layers tapered on the sealing side makes up part or all of the multilayered sealing layer according to the invention in this process. The on the other side tapered web can be made of plastics such as the above polymers, metals, cardboard, paper, cardboard, textiles, nonwovens, woven or bonded from the substances mentioned.

If carrier web and the multilayer sealing layer according to the invention are prefabricated separately, they can also be joined by using a laminating adhesive to form the packaging material according to the invention. In this case, the multilayered sealing layer may in turn have been produced as a blown film or as a flat film and the carrier web made of plastics, such as the above-mentioned polymers, metals, cardboard, paper, cardboard, textiles, nonwovens, woven or bonded from the substances mentioned.

The multilayer sealing layer according to the invention can also be subjected to a stretching process after the extrusion. The orientation can only take place in the longitudinal direction, only in the transverse direction, first in the longitudinal and then in the transverse direction, simultaneously in the longitudinal and transverse direction or in combinations of these steps. In this case, the stretching for the multilayered sealing layer can be carried out alone or for the packaging material containing it.

<b>Examples</b>

Series 1, Example 1.1:

A sealing layer with the structure PE-LD-1 // (80% PE-LLD + 20% PE-LD-2) with the layer thicknesses 40 .mu.m // 20 .mu.m was prepared by coextrusion as a blown film and with a laminating adhesive against commercial biaxially stretched Polyamide of thickness 15 microns laminated.

PE-LD-1 has a density of 0.918 g / cm³, a melting point of 106 ° C and a MFR of 3.7 g / 10min at 190 ° C and 2.16 kg. PE-LD-2 has a density of 0.923 g / cm³, a melting point of 108 ° C and a MFR of 2 g / 10min at 190 ° C and 2.16 kg and is equipped with 500 ppm of erucic acid amide and 1000 ppm of silica of average particle size 15 microns. PE-LLD is an ethylene-octene co-polymer having a density of 0.920 g / cm³, a melting point of 124 ° C and a MFR of 1.1 g / 10min at 190 ° C and 2.16 kg.

Series 1, Example 1.2:

Laminate from example 1.1, wherein the sealing layer has the structure PE-LD-3 // structure (80% PE-LLD + 20% PE-LD-2) with the layer thicknesses 40 microns // 20 microns and was prepared as in Example 1.1 , The difference to Example 1.1 is between PE-LD-1 and PE-LD-3, where PE-LD-3 has a density of 0.915 g / cm³, has a melting point of 104 ° C and an MFR of 8 g / 10min at 190 ° C and 2.16 kg.

Test Series 1, Comparative Example 1.3:

Laminate from Example 1.1, wherein the sealing layer has the structure PE-LD-4 // (80% PE-LLD + 20% PE-LD-2) with the layer thicknesses 40 microns // 20 microns and was prepared as in Example 1.1. The difference to Example 1.1 is between PE-LD-1 and PE-LD-4, wherein PE-LD-4 has a density of 0.923 g / cm³, has a melting point of 111 ° C and an MFR of 0.9 g / 10min at 190 ° C and 2.16kg.

Series 2, Example 2.1:

Laminate as in Example 1.1, wherein the sealing layer has the structure E / VA-1 // E-VA-2 in the thicknesses 35 microns // 15 microns. Both E / VA copolymers have a vinyl acetate content of 5.0%, a density of 0.925 g / cm³ and a melting point of 101 ° C. At 190 ° C and 2.16 kg, E / VA-1 has an MFR of 8 g / 10 min and E / VA-2 has an MFR of 2 g / 10 min.

Series 2, Comparative Example 2.2:

Laminate as in Example 1.1, wherein the sealing layer has the single-layer structure E / VA-2 in the thickness of 50 microns. E / VA-2 corresponds to the polymer of the same name from Example 3.

Series 2, Comparative Example 2.3:

Laminate as in Example 2.1, wherein the sealing layer has the structure E / VA-2 // E-VA-1 in the thicknesses 15 μm // 35 μm. Both E / VA copolymers have a vinyl acetate content of 5.0%, a density of 0.925 g / cm³ and a melting point of 101 ° C. At 190 ° C and 2.16 kg, E / VA-1 has an MFR of 8 g / 10 min and E / VA-2 has an MFR of 2 g / 10 min.

Series 3, Example 3.1:

Laminate as in example 1.1, wherein the sealing layer has the structure PE-LD-5 // E / VA-1 // (60% mPE-LLD + 40% PE-LD-6) in the thicknesses 10 μm // 30 μm / / 10 microns has. PE-LD-5 has a density of 0.922 g / cm³, a melting point of 109 ° C and an MFR of 0.3 g / 10min at 190 ° C and 2.16 kg, PE-LD-6 has a density of 0.919 g / cm³, a melting point of 105 ° C and a MFR of 0.3 g / 10min at 190 ° C and 2.16 kg, mPE-LLD has a density of 0.902 g / cm³, a melting point of 100 ° C and an MFR of 1 g / 10min at 190 ° C and 2.16 kg. mPE-LLD is made with a metallocene catalyst. E / VA-1 corresponds to the polymer of the same name from Example 2.1.

Series 3, Comparative Example 3.2:

Laminate from Example 1.1, wherein the sealing layer has the structure (60% mPE-LLD + 40% PE-LD-6) with the thickness of 50 microns and as prepared in Example 1.1. The polymers mPE-LLD and PE-LD-6 correspond to the eponymous types from Example 3.1.

On the exemplary films according to the invention and on the comparative examples, the following properties were measured as follows:<ul id="ul0003" list-style="none"><li>• Seal strength From the film web to be tested, two clean, clean sample strips are removed. For sealing, they are stacked with the surfaces to be sealed and held between the sealing jaws so that the sample protrudes at least 1 cm on each side. The seal is perpendicular to the film direction. The sealing jaws are smooth and heated on both sides to the nominal sealing temperature. The sealing is done by default for 0.5 seconds with a pressure of 50 N / cm², Exemplary comparative measurements were also carried out for shorter sealing times. In the tables below, data given without indication of the sealing time always refer to a sealing time of 0.5 s. Deviating test conditions are specified. After cooling, a 15 mm wide test strip is cut out of the seal seam produced in this way and tested on a tensile testing machine at a speed of 100 mm / min and a clamping length of 20 mm. The maximum value of the force required to cut the sealed films is recorded as the seal strength.</li><li>• Hottack power From the material to be tested in running direction approx. 90 mm long and 45 mm wide sample strips, which are clamped with the sealing sides against each other in the sample holder. The sealing takes place with the same conditions regarding sealing tool, pressure and time as for the seal strength, ie over a 20 mm wide area. Immediately after completion of the seal test, the strength of the warm seal seam at a take-off speed of 25 m / min takes place. The force curve is measured electronically and stored by PC. The maximum value of the force is read from a graph of the force curve.</li><li>• seam tightness The material to be tested is cut out in the format 20 x 20 cm and folded on one edge with the sides to be sealed. This edge is then in the under<img file="EP0936062A2_D0001.tif" />Seal strength "described manner sealed, the resulting seal is called <img file="EP0936062A2_D0002.tif" />Longitudinal seam ". The tube thus formed is then sealed in the same way on one of the open transverse sides with flattened longitudinal seam. The flattened longitudinal seam forms a fold. In the thus formed half-bag is in the seam gusset of longitudinal and transverse seams an approx. 5 mm high bottom filled with methylene blue colored methanol. Any needles in the suture are indicated by the methylene blue solution passing through them. It is noted whether leaks occur or whether the cross seam is tightly sealed across the entire width.</li></ul>

The results are summarized in the following tables: <tables id="tabl0001" num="0001"><table frame="all"><tgroup cols="5" colsep="1" rowsep="1"><colspec colnum="1" colname="col1" colwidth="31.50mm" /><colspec colnum="2" colname="col2" colwidth="31.50mm" /><colspec colnum="3" colname="col3" colwidth="31.50mm" /><colspec colnum="4" colname="col4" colwidth="31.50mm" /><colspec colnum="5" colname="col5" colwidth="31.50mm" /><thead valign="top"><row><entry namest="col1" nameend="col1" rowsep="0" align="center">feature</entry><entry namest="col2" nameend="col2" rowsep="0" align="center">unit</entry><entry namest="col3" nameend="col5" align="center">Example or comparative example</entry></row><row><entry namest="col1" nameend="col1" /><entry namest="col2" nameend="col2" /><entry namest="col3" nameend="col3" align="center">Example 1.1</entry><entry namest="col4" nameend="col4" align="center">Ex. 1.2</entry><entry namest="col5" nameend="col5" align="center">See 1.3</entry></row></thead><tbody valign="top"><row><entry namest="col1" nameend="col1" align="left">Seal strength at 100 ° C</entry><entry namest="col2" nameend="col2" align="left">N / 15 mm</entry><entry namest="col3" nameend="col3" align="char" char=",">0.5</entry><entry namest="col4" nameend="col4" align="char" char=",">0.6</entry><entry namest="col5" nameend="col5" align="char" char=",">0.5</entry></row><row><entry namest="col1" nameend="col1" align="left">Seal strength at 110 ° C</entry><entry namest="col2" nameend="col2" align="left">N / 15 mm</entry><entry namest="col3" nameend="col3" align="char" char=",">5.4</entry><entry namest="col4" nameend="col4" align="char" char=",">4.6</entry><entry namest="col5" nameend="col5" align="char" char=",">5.2</entry></row><row><entry namest="col1" nameend="col1" align="left">Seal strength at 120 ° C</entry><entry namest="col2" nameend="col2" align="left">N / 15 mm</entry><entry namest="col3" nameend="col3" align="char" char=",">39.2</entry><entry namest="col4" nameend="col4" align="char" char=",">40.7</entry><entry namest="col5" nameend="col5" align="char" char=",">43.6</entry></row><row><entry namest="col1" nameend="col1" align="left">Seal strength at 130 ° C</entry><entry namest="col2" nameend="col2" align="left">N / 15 mm</entry><entry namest="col3" nameend="col3" align="char" char=",">45.4</entry><entry namest="col4" nameend="col4" align="char" char=",">44.8</entry><entry namest="col5" nameend="col5" align="char" char=",">46.0</entry></row><row><entry namest="col1" nameend="col1" align="left">maximum hottack power at 100 ° C</entry><entry namest="col2" nameend="col2" align="left">N / 45 mm</entry><entry namest="col3" nameend="col3" align="char" char=",">4.2</entry><entry namest="col4" nameend="col4" align="char" char=",">5.1</entry><entry namest="col5" nameend="col5" align="char" char=",">4.9</entry></row><row><entry namest="col1" nameend="col1" align="left">maximum hottack power at 110 ° C</entry><entry namest="col2" nameend="col2" align="left">N / 45 mm</entry><entry namest="col3" nameend="col3" align="char" char=",">21.6</entry><entry namest="col4" nameend="col4" align="char" char=",">22.5</entry><entry namest="col5" nameend="col5" align="char" char=",">23.1</entry></row><row><entry namest="col1" nameend="col1" align="left">maximum hottack power at 120 ° C</entry><entry namest="col2" nameend="col2" align="left">N / 45 mm</entry><entry namest="col3" nameend="col3" align="char" char=",">47.0</entry><entry namest="col4" nameend="col4" align="char" char=",">45.9</entry><entry namest="col5" nameend="col5" align="char" char=",">50.1</entry></row><row><entry namest="col1" nameend="col1" align="left">maximum hottack power at 130 ° C</entry><entry namest="col2" nameend="col2" align="left">N / 45 mm</entry><entry namest="col3" nameend="col3" align="char" char=",">35.1</entry><entry namest="col4" nameend="col4" align="char" char=",">32.8</entry><entry namest="col5" nameend="col5" align="char" char=",">37.6</entry></row><row><entry namest="col1" nameend="col1" align="left">Needles in bag with seal 100 ° C</entry><entry namest="col2" nameend="col2" align="left">Yes No</entry><entry namest="col3" nameend="col3" align="char" char=",">Yes</entry><entry namest="col4" nameend="col4" align="char" char=",">Yes</entry><entry namest="col5" nameend="col5" align="char" char=",">Yes</entry></row><row><entry namest="col1" nameend="col1" align="left">Needles in bag with seal 110 ° C</entry><entry namest="col2" nameend="col2" align="left">Yes No</entry><entry namest="col3" nameend="col3" align="char" char=",">Yes</entry><entry namest="col4" nameend="col4" align="char" char=",">No</entry><entry namest="col5" nameend="col5" align="char" char=",">Yes</entry></row><row><entry namest="col1" nameend="col1" align="left">Needles in bag with seal 115 ° C</entry><entry namest="col2" nameend="col2" align="left">Yes No</entry><entry namest="col3" nameend="col3" align="char" char=",">No</entry><entry namest="col4" nameend="col4" align="char" char=",">No</entry><entry namest="col5" nameend="col5" align="char" char=",">Yes</entry></row><row><entry namest="col1" nameend="col1" align="left">Needles in bag with seal 120 ° C</entry><entry namest="col2" nameend="col2" align="left">Yes No</entry><entry namest="col3" nameend="col3" align="char" char=",">No</entry><entry namest="col4" nameend="col4" align="char" char=",">No</entry><entry namest="col5" nameend="col5" align="char" char=",">Yes</entry></row><row rowsep="1"><entry namest="col1" nameend="col1" align="left">Needles in bag with seal 130 ° C</entry><entry namest="col2" nameend="col2" align="left">Yes No</entry><entry namest="col3" nameend="col3" align="char" char=",">No</entry><entry namest="col4" nameend="col4" align="char" char=",">No</entry><entry namest="col5" nameend="col5" align="char" char=",">Yes</entry></row></tbody></tgroup></table></tables>

<i>Properties of films according to the invention and comparison samples, test series 1</i><tables id="tabl0002" num="0002"><table frame="all"><tgroup cols="5" colsep="1" rowsep="1"><colspec colnum="1" colname="col1" colwidth="31.50mm" /><colspec colnum="2" colname="col2" colwidth="31.50mm" /><colspec colnum="3" colname="col3" colwidth="31.50mm" /><colspec colnum="4" colname="col4" colwidth="31.50mm" /><colspec colnum="5" colname="col5" colwidth="31.50mm" /><thead valign="top"><row><entry namest="col1" nameend="col1" rowsep="0" align="center">feature</entry><entry namest="col2" nameend="col2" rowsep="0" align="center">unit</entry><entry namest="col3" nameend="col5" align="center">Example or comparative example</entry></row><row><entry namest="col1" nameend="col1" /><entry namest="col2" nameend="col2" /><entry namest="col3" nameend="col3" align="center">Example 2.1</entry><entry namest="col4" nameend="col4" align="center">See 2.2</entry><entry namest="col5" nameend="col5" align="center">See 2.3</entry></row></thead><tbody valign="top"><row><entry namest="col1" nameend="col1" align="left">Seal strength at 90 ° C</entry><entry namest="col2" nameend="col2" align="left">N / 15 mm</entry><entry namest="col3" nameend="col3" align="char" char=",">0.7</entry><entry namest="col4" nameend="col4" align="char" char=",">0.3</entry><entry namest="col5" nameend="col5" align="char" char=",">0.5</entry></row><row><entry namest="col1" nameend="col1" align="left">Seal strength at 100 ° C</entry><entry namest="col2" nameend="col2" align="left">N / 15 mm</entry><entry namest="col3" nameend="col3" align="char" char=",">25.3</entry><entry namest="col4" nameend="col4" align="char" char=",">23.9</entry><entry namest="col5" nameend="col5" align="char" char=",">24.6</entry></row><row><entry namest="col1" nameend="col1" align="left">Seal strength at 110 ° C</entry><entry namest="col2" nameend="col2" align="left">N / 15 mm</entry><entry namest="col3" nameend="col3" align="char" char=",">33.8</entry><entry namest="col4" nameend="col4" align="char" char=",">32.0</entry><entry namest="col5" nameend="col5" align="char" char=",">34.7</entry></row><row><entry namest="col1" nameend="col1" align="left">Seal strength at 120 ° C</entry><entry namest="col2" nameend="col2" align="left">N / 15 mm</entry><entry namest="col3" nameend="col3" align="char" char=",">34.2</entry><entry namest="col4" nameend="col4" align="char" char=",">35.7</entry><entry namest="col5" nameend="col5" align="char" char=",">33.2</entry></row><row><entry namest="col1" nameend="col1" align="left">maximum hottack power at 90 ° C</entry><entry namest="col2" nameend="col2" align="left">N / 45 mm</entry><entry namest="col3" nameend="col3" align="char" char=",">4.1</entry><entry namest="col4" nameend="col4" align="char" char=",">3.4</entry><entry namest="col5" nameend="col5" align="char" char=",">2.2</entry></row><row><entry namest="col1" nameend="col1" align="left">maximum hottack power at 100 ° C</entry><entry namest="col2" nameend="col2" align="left">N / 45 mm</entry><entry namest="col3" nameend="col3" align="char" char=",">9.7</entry><entry namest="col4" nameend="col4" align="char" char=",">10.5</entry><entry namest="col5" nameend="col5" align="char" char=",">2.9</entry></row><row><entry namest="col1" nameend="col1" align="left">maximum hottack power at 110 ° C</entry><entry namest="col2" nameend="col2" align="left">N / 45 mm</entry><entry namest="col3" nameend="col3" align="char" char=",">7.5</entry><entry namest="col4" nameend="col4" align="char" char=",">8.3</entry><entry namest="col5" nameend="col5" align="char" char=",">2.5</entry></row><row><entry namest="col1" nameend="col1" align="left">maximum hottack power at 120 ° C</entry><entry namest="col2" nameend="col2" align="left">N / 45 mm</entry><entry namest="col3" nameend="col3" align="char" char=",">6.0</entry><entry namest="col4" nameend="col4" align="char" char=",">7.5</entry><entry namest="col5" nameend="col5" align="char" char=",">1.9</entry></row><row><entry namest="col1" nameend="col1" align="left">Needles in bag with seal 90 ° C</entry><entry namest="col2" nameend="col2" align="left">Yes No</entry><entry namest="col3" nameend="col3" align="char" char=",">Yes</entry><entry namest="col4" nameend="col4" align="char" char=",">Yes</entry><entry namest="col5" nameend="col5" align="char" char=",">Yes</entry></row><row><entry namest="col1" nameend="col1" align="left">Needles in bag with seal 100 ° C</entry><entry namest="col2" nameend="col2" align="left">Yes No</entry><entry namest="col3" nameend="col3" align="char" char=",">Yes</entry><entry namest="col4" nameend="col4" align="char" char=",">Yes</entry><entry namest="col5" nameend="col5" align="char" char=",">Yes</entry></row><row><entry namest="col1" nameend="col1" align="left">Needles in bag with seal 110 ° C</entry><entry namest="col2" nameend="col2" align="left">Yes No</entry><entry namest="col3" nameend="col3" align="char" char=",">No</entry><entry namest="col4" nameend="col4" align="char" char=",">Yes</entry><entry namest="col5" nameend="col5" align="char" char=",">No</entry></row><row rowsep="1"><entry namest="col1" nameend="col1" align="left">Needles in bag with seal 120 ° C</entry><entry namest="col2" nameend="col2" align="left">Yes No</entry><entry namest="col3" nameend="col3" align="char" char=",">No</entry><entry namest="col4" nameend="col4" align="char" char=",">Yes</entry><entry namest="col5" nameend="col5" align="char" char=",">No</entry></row></tbody></tgroup></table></tables>

<i>Properties of films according to the invention and comparison samples, test series 2</i><tables id="tabl0003" num="0003"><table frame="all"><tgroup cols="4" colsep="1" rowsep="1"><colspec colnum="1" colname="col1" colwidth="39.37mm" /><colspec colnum="2" colname="col2" colwidth="39.37mm" /><colspec colnum="3" colname="col3" colwidth="39.37mm" /><colspec colnum="4" colname="col4" colwidth="39.37mm" /><thead valign="top"><row><entry namest="col1" nameend="col1" rowsep="0" align="center">feature</entry><entry namest="col2" nameend="col2" rowsep="0" align="center">unit</entry><entry namest="col3" nameend="col4" align="center">Example or comparative example</entry></row><row><entry namest="col1" nameend="col1" /><entry namest="col2" nameend="col2" /><entry namest="col3" nameend="col3" align="center">Example 3.1</entry><entry namest="col4" nameend="col4" align="center">See 3.2</entry></row></thead><tbody valign="top"><row><entry namest="col1" nameend="col1" align="left">Seal strength at 80 ° C</entry><entry namest="col2" nameend="col2" align="left">N / 15 mm</entry><entry namest="col3" nameend="col3" align="char" char=",">0.4</entry><entry namest="col4" nameend="col4" align="char" char=",">0.6</entry></row><row><entry namest="col1" nameend="col1" align="left">Seal strength at 90 ° C</entry><entry namest="col2" nameend="col2" align="left">N / 15 mm</entry><entry namest="col3" nameend="col3" align="char" char=",">10.8</entry><entry namest="col4" nameend="col4" align="char" char=",">11.2</entry></row><row><entry namest="col1" nameend="col1" align="left">Seal strength at 100 ° C</entry><entry namest="col2" nameend="col2" align="left">N / 15 mm</entry><entry namest="col3" nameend="col3" align="char" char=",">44.0</entry><entry namest="col4" nameend="col4" align="char" char=",">46.2</entry></row><row><entry namest="col1" nameend="col1" align="left">Seal strength at 110 ° C</entry><entry namest="col2" nameend="col2" align="left">N / 15 mm</entry><entry namest="col3" nameend="col3" align="char" char=",">46.9</entry><entry namest="col4" nameend="col4" align="char" char=",">49.8</entry></row><row><entry namest="col1" nameend="col1" align="left">Seal strength at 1 20 ° C</entry><entry namest="col2" nameend="col2" align="left">N / 15 mm</entry><entry namest="col3" nameend="col3" align="char" char=",">50.3</entry><entry namest="col4" nameend="col4" align="char" char=",">58.1</entry></row><row><entry namest="col1" nameend="col1" align="left">maximum hottack power at 80 ° C</entry><entry namest="col2" nameend="col2" align="left">N / 45 mm</entry><entry namest="col3" nameend="col3" align="char" char=",">4.5</entry><entry namest="col4" nameend="col4" align="char" char=",">3.4</entry></row><row><entry namest="col1" nameend="col1" align="left">maximum hottack power at 90 ° C</entry><entry namest="col2" nameend="col2" align="left">N / 45 mm</entry><entry namest="col3" nameend="col3" align="char" char=",">25.4</entry><entry namest="col4" nameend="col4" align="char" char=",">23.1</entry></row><row><entry namest="col1" nameend="col1" align="left">maximum hottack power at 100 ° C</entry><entry namest="col2" nameend="col2" align="left">N / 45 mm</entry><entry namest="col3" nameend="col3" align="char" char=",">29.8</entry><entry namest="col4" nameend="col4" align="char" char=",">30.5</entry></row><row><entry namest="col1" nameend="col1" align="left">maximum hottack power at 110 ° C</entry><entry namest="col2" nameend="col2" align="left">N / 45 mm</entry><entry namest="col3" nameend="col3" align="char" char=",">27.2</entry><entry namest="col4" nameend="col4" align="char" char=",">34.5</entry></row><row><entry namest="col1" nameend="col1" align="left">maximum hottack power at 120 ° C</entry><entry namest="col2" nameend="col2" align="left">N / 45 mm</entry><entry namest="col3" nameend="col3" align="char" char=",">24.0</entry><entry namest="col4" nameend="col4" align="char" char=",">19.9</entry></row><row><entry namest="col1" nameend="col1" align="left">Needles in bag with seal 90 ° C</entry><entry namest="col2" nameend="col2" align="left">Yes No</entry><entry namest="col3" nameend="col3" align="char" char=",">Yes</entry><entry namest="col4" nameend="col4" align="char" char=",">Yes</entry></row><row><entry namest="col1" nameend="col1" align="left">Needles in bag with seal 100 ° C</entry><entry namest="col2" nameend="col2" align="left">Yes No</entry><entry namest="col3" nameend="col3" align="char" char=",">Yes</entry><entry namest="col4" nameend="col4" align="char" char=",">Yes</entry></row><row><entry namest="col1" nameend="col1" align="left">Needles in bag with seal 110 ° C</entry><entry namest="col2" nameend="col2" align="left">Yes No</entry><entry namest="col3" nameend="col3" align="char" char=",">No</entry><entry namest="col4" nameend="col4" align="char" char=",">Yes</entry></row><row><entry namest="col1" nameend="col1" align="left">Needles in bag with seal 120 ° C</entry><entry namest="col2" nameend="col2" align="left">Yes No</entry><entry namest="col3" nameend="col3" align="char" char=",">No</entry><entry namest="col4" nameend="col4" align="char" char=",">Yes</entry></row><row><entry namest="col1" nameend="col1" align="left">Seal strength at 120 ° C, seal time = 0.25 s</entry><entry namest="col2" nameend="col2" align="left">N / 15 mm</entry><entry namest="col3" nameend="col3" align="char" char=",">47.2</entry><entry namest="col4" nameend="col4" align="char" char=",">48.8</entry></row><row><entry namest="col1" nameend="col1" align="left">maximum hottack force at 120 ° C, sealing time = 0.25 s</entry><entry namest="col2" nameend="col2" align="left">N / 45 mm</entry><entry namest="col3" nameend="col3" align="char" char=",">28.3</entry><entry namest="col4" nameend="col4" align="char" char=",">29.6</entry></row><row rowsep="1"><entry namest="col1" nameend="col1" align="left">Needles with sealing 120 ° C, sealing time = 0.25 s</entry><entry namest="col2" nameend="col2" align="left">Yes No</entry><entry namest="col3" nameend="col3" align="char" char=",">No</entry><entry namest="col4" nameend="col4" align="char" char=",">Yes</entry></row></tbody></tgroup></table></tables>

<i>Properties of films according to the invention and comparison samples, test series 3</i>

The required hermetically sealed seal is achieved by the sealing layer according to the invention in the embodiments shown as an example, even at significantly lower sealing temperatures than comparable types according to the prior art. Hottack and seal strength are not negatively affected. The achieved at lower temperatures cannula freedom but also means that this is possible with the same sealing temperature and shortened sealing time. This circumstance was exemplified for the test series 3.