CN103313852B - Non-foil packaging laminate and its manufacture method and the packing container being made from - Google Patents

Abstract

The present invention relates to a foil-free packaging laminate for liquid food packaging comprising a layer of paper or other cellulose-based material, an outermost layer of a liquid-tight, heat-sealable polyolefin-based polymer, and a vapor deposited overlying Inductive thermosensitive metal layer on the inner side of the paper or cellulose based material layer. The invention also relates to a method for producing a packaging laminate, to a packaging container made of the packaging laminate and to a method of induction heat sealing the packaging laminate into a packaging container.

Description

Foil-free packaging laminate, method of making same, and packaging container made therefrom

technical field

The present invention relates to a foil-free packaging laminate for induction heat sealing into packages for liquid food or beverages. The invention also relates to a method of making a packaging laminate and a method of induction heat sealing the non-foil packaging laminate to form a packaging container from the packaging laminate.

Background technique

Single-use packaging containers for liquid foods are usually manufactured from paperboard or carton based packaging laminates. One such common packaging container is known under the trademark Tetra Brik It is sold in the market and is mainly used for aseptic packaging for long-term normal temperature storage of sold liquid foods such as milk and juice. The packaging material of such known packaging containers is generally a laminate comprising a main body core layer of paper or cardboard and an outer, liquid-tight thermoplastic layer. In order to make such packaging containers (such as aseptic packaging and packaging for milk or juice) air-tight, especially oxygen-tight, the laminates in these packaging containers usually include at least one additional layer, most commonly aluminum foil .

On the inside of the laminate, i.e. the side intended to face the filled food ingredients of containers made of the laminate, there is an innermost layer applied to the aluminum foil, which may consist of one or more sheets comprising Layer composition of heat sealable adhesive polymers and/or polyolefins. Also on the outside of the paper or paperboard layer, there is an outermost heat-sealable polymer layer.

Furthermore, the aluminum foil makes the packaging material heat-sealable by means of induction heat sealing, which is a fast and efficient method for obtaining a mechanically strong, liquid-tight and gas-tight connection or Seam sealing technology.

Said packaging containers are usually produced by modern, high-speed types of packaging machines for forming, filling and sealing packaging material webs or packaging material preforms into packages. The packaging container can thus be manufactured by forming a web of laminated packaging material into a tube which can be formed by joining the two longitudinal edges of said web at the overlap by interposing inner and outer heat-sealable thermoplastic polymer layers. Melted together to form with each other. The tube is filled with the intended liquid food product and then divided into a plurality of tubes by repeated transverse sealing of the tube at positions spaced a predetermined distance below the liquid level of the liquid food within the tube Individual packages. The packages are separated from the tube by cutting along transverse sealing lines and given the desired geometry (usually parallelepiped) by folding along prepared crease lines on the packaging material.

The main advantage of this continuous method of tube forming, filling and sealing packaging is that the web can be tube formed immediately after continuous sterilization, thus enabling an aseptic packaging method, which The method is a method in which the bacteria of the liquid food to be filled and the packaging material itself are reduced and the filled packaging container is produced in a clean environment, so that the filled packaging can be It can also be stored for longer periods of time without the risk of microbial growth in the filled product. This continuous, trademarked Tetra Another important advantage of this type of packaging method is that, as mentioned above, it is possible to carry out continuous high-speed packaging, which greatly saves costs.

The aluminum foil layer within the packaging laminate has excellent gas barrier properties compared to most polymeric gas barrier materials. This traditional aluminum foil-based packaging laminate material for aseptic packaging of liquid food is a very cost-effective and cost-effective packaging material, which is available in the market. Any other competing material must have better raw material cost-effectiveness, comparable food preservation properties and comparable ease of conversion into finished packaging laminates.

There is a growing trend today to develop a packaging material that does not have aluminum foil in the laminate structure, seeking to improve the environmental profile of the target material. It is of course also desirable to reduce the production costs of packaging materials and to maintain the necessary properties for sterile long-term storage of packaging containers produced from such packaging laminates.

Also, it would be ideal if the packaging laminate could be adapted for direct use on installed and running filling and packaging machines at dairies and filling sites around the world. Packaging laminates without aluminum foil then present a technical problem to be solved with regard to the heat sealing of the outermost thermoplastic layer, since there is no longer in the laminate the ability to induce current from a magnetic field as the aluminum foil does to Materials that generate heat. However, alternative technologies have been discussed and developed, such as generating heat by ultrasonic resonance or the old traditional convection and hot air sealing methods. The implementation of this alternative sealing technology will result in having to completely rebuild the sealing components of the packaging machines already installed in dairies and filling facilities.

Packaging laminates comprising two or more barrier layers, one of which is a metallized layer, have been found to be viable alternatives to aluminum foil-based laminates, however, as described above , the current induction heat sealing equipment cannot use this substitute.

However, it has been found that, contrary to all previous beliefs, it is possible, with some minor modifications to existing machinery, to produce sufficient melting of the adjacent thermoplastic layer by means of the metallized layer by induction heat sealing. of heat. The first metallized layers tested were mainly coated on oriented PET film substrates.

However, according to continuing work on the improvement of induction sealing technology for metallised layers, it has been found that different substrates are different in their suitability for metallization and subsequent induction heat sealing. In order to work well, the metallization layer appears to have some combination of thickness or optical density and quality of the layer. By mass it is primarily meant that the layer should be uniform and have substantially the same thickness over the entire width and length of the laminated packaging material.

PET film substrates are generally expensive due to their importance in packaging laminates of the type described above. In fact, its important role for packaging laminates is only as a carrier for the metallization layer. Although it is believed that the induction sealing technique can and may be adapted for use with other, lower priced polymeric substrates, it has been found that the sealing process may require more adjustment and inspection in order for it to operate effectively and reliably. It has been found that the choice of substrate can affect the quality and durability of the metallization during the heat sealing process.

Therefore, there remains a need for a cost-effective, durable (i.e., reliable under appropriate variations in production and handling conditions) package for aseptic liquid food packaging (for example, milk or other beverage packaging) without aluminum foil A material that provides sufficient barrier properties in a packaging container for long-term sterile storage at room temperature and that is induction-sealable on installed fill and seal equipment.

Contents of the invention

It is therefore an object of the present invention to solve or alleviate the above-mentioned problems in producing foilless induction heat-sealable paper or paperboard packaging laminates.

Another object of the present invention is to provide a foil-free, paper or paperboard packaging laminate suitable for long-term aseptic packaging of liquid or aqueous foods, which can be heat-sealed into packaging containers by induction heat sealing techniques, and The packaging container has better liquid tightness and air tightness.

It is a further object of the present invention to provide a cost-effective, foil-free paper or paperboard packaging laminate suitable for long-term aseptic packaging of liquid or water-containing foods, which can be heat sealed by induction heat sealing technology. Sealed into a packaging container with good liquid-tightness and air-tightness, the packaging container not only has good barrier properties to gas and water vapor, but also has good barrier properties to light and odorous substances. Accordingly, these objects are achieved according to a foil-free packaging laminate capable of being induction heat-sealed into a package for liquid food or beverages, the packaging laminate comprising at least one first layer of paper or other cellulose-based material, the first A paper layer is located on the inside of the packaging laminate and is pre-coated to receive and support the induction thermosensitive metal vapor deposition layer to cause heat sealing of the thermoplastic polymer material, the packaging laminate also comprising such a metal vapor deposited layer applied to the inside of said pre-coated first paper or cellulose-based material layer, and further comprising an orientation film laminated to the metal vapor deposition layer; and further comprising applying to the orientation an innermost liquid-tight, heat-sealable layer of thermoplastic polymeric material on the inner side of the film; and/or said oriented film comprises a liquid-tight heat-seal layer representing the innermost layer of the film, wherein said The oriented film is stretched at a stretch ratio of 2 or higher in at least one direction, and has a core layer of a material having a higher melting point than that of the innermost layer.

In one aspect, the alignment film is applied to the metal vapor deposited layer via an intermediate adhesive layer and/or the alignment film comprises an adhesive layer on its outer side to be laminated to the metal vapor deposited layer.

In one aspect of the present invention there is provided a method of making a foilless packaging laminate comprising the steps of: providing a first layer of paper or other fiber-based material by applying an induction seal durable layer to the paper or The paper or other layer of cellulose-based material is precoated on the inner side of the layer of other cellulose-based material to receive and support an induction thermosensitive metal vapor deposition layer, which is applied to the coated On the inner side of the clad paper layer, provided is a core of material stretched in at least one direction with a draw ratio of 2 or higher and having a higher melting point than the material of the innermost layer of the non-foil packaging laminate an oriented film (20) of layers, laminating the oriented film to a metal-coated paper layer, providing one or more layers of liquid-tight, heat-sealable thermoplastic polymer material applied to the inner side of the oriented film, and/or providing as part of the oriented film a liquid-tight heat-seal layer representing the innermost layer of the film, wherein the liquid-tight, heat-sealable thermoplastic polymer material of the film or the liquid-tight heat-seal layer represents The innermost layer of the foilless packaging laminate.

In one aspect, the objects of the invention are achieved by a packaging container manufactured from the above-mentioned packaging laminate.

In one aspect, the objects of the invention are achieved by a method of heat sealing a foilless packaging laminate comprising the steps of: providing a foilless packaging laminate as described above in the form of a continuous roll, laminating the rolled packaging forming a continuous tube of material and applying a longitudinal seal in the longitudinal direction, filling said packaging laminate tube with liquid food, forming heat-sealed areas at predetermined intervals in a transverse direction of said filled tube by induction heating, and cut along the centerline of each transverse seal area to form individual containers.

Description of drawings

Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings, in which:

Figures 1a, 1a2, 1b, 1b2, 1b3, 1b4, 1c and 1c2 schematically show in section a first, second, third and fourth embodiment of a packaging laminate manufactured according to the invention ,

Figure 2 schematically shows a method of liquid coating a polymeric composition onto a paper substrate layer,

Figure 3 is a schematic view of an apparatus for vapor deposition of a preferred metal layer onto a substrate,

Figures 4a and 4b schematically show an exemplary method of producing the packaging laminate described in Figure 1,

Figures 5a and 5b show an example of a packaging container produced from a packaging laminate according to the invention, and

Figure 6 shows the principle of how this packaging container is made in a continuous forming, filling and sealing process.

detailed description

According to one aspect of the present invention, the general object is achieved by a foil-free packaging laminate capable of induction heat sealing into a package for liquid food or beverages, the packaging laminate comprising at least a first paper or other cellulose based a layer of material, the first paper layer being on the inside of said packaging laminate and pre-coated to receive and support an induction thermosensitive metal vapor deposition layer to cause heat sealing of thermoplastic polymer material, said packaging laminate further comprising such a metal vapor deposited layer applied to the inside of said precoated first paper or cellulose-based material layer, and further comprising an orientation film laminated to the metal vapor deposited layer; and further comprising applying to The innermost liquid-tight, heat-sealable thermoplastic polymer material layer on the inside of the oriented film; and/or the oriented film comprises a liquid-tight heat-seal layer, representing the innermost film layer, wherein the oriented film is in at least one direction The core layer is stretched at a draw ratio of 2 or higher and has a material having a higher melting point than that of the innermost layer.

The alignment film is laminated to the metal vapor deposition layer through an intermediate adhesive layer and/or the alignment film includes an adhesive layer on its outer side to be laminated to the metal vapor deposition layer. According to a well-functioning embodiment of the present invention, in order to provide a smooth receiving surface for the metal vapor deposited coating and in order to prepare the paper to support the metal coating in a better manner during the subsequent heat sealing operation, the first A layer of paper or other cellulose-based material is coated on the inside with an induction-seal durable coating having a higher melting point than the innermost layer of heat-sealable material. Subsequently, the inner side of the induction heat-seal durable coating is further applied with an induction heat-sensitive metal vapor deposition coating adapted to induce a heat seal in the adjacent thermoplastic polymer layer.

In preparation for metal vapor deposition coatings, the most cost-effective method of applying such coatings to the paper layer is by a liquid coating method (often also commonly referred to as liquid film coating or dispersion coating). Cloth) the coating liquid composition comprising an induction-seal durable polymer binder dispersed or dissolved in a water or solvent medium is applied to the paper layer and then dried.

According to some well-working embodiments, the induction-seal durable coating is made from a composition consisting essentially of a polymer selected from the group consisting of polyvinyl alcohol (PVOH), water-dispersible ethylene vinyl alcohol copolymer (EVOH), Ethylene vinyl alcohol vinyl acetate copolymer, polyvinylidene chloride (PVDC), water dispersible polyamide (PA), water dispersible polyester, polysaccharides, polysaccharide derivatives (including starch and starch derivatives) And groups consisting of combinations of two or more of these substances. Importantly, the coating thus has a higher melting point than the innermost layer of thermoplastic material or the liquid-tight heat-seal layer of the oriented film, by means of which coating the packaging laminate can be heat-sealed into a filled and sealed package. The seal durable coating is a thermomechanically stable layer. Preferably, the outer and innermost said thermoplastic heat-sealable material and liquid-tight heat-seal layer are based on polyolefins, more preferably on polyethylene, most preferably on low density polyethylene, such as LDPE, LLDPE, m - LLDPE and VLDPE and mixtures thereof.

The induction seal durable coating is formed from a composition mainly comprising PVOH, water dispersible EVOH or starch when it is desired to use polymers with better cost-effectiveness and positive environmental profile. Water-dispersible EVOH has a higher number of vinyl alcohol units than melt processable EVOH, and is more similar in nature to PVOH than to EVOH. Pure PVOH and starch-based polymers are more or less biodegradable, which is why such polymers are preferable in some packaging applications.

In addition, some polymer binders suitable for liquid application also have gas barrier properties, which makes them advantageous in packaging films. Accordingly, the induction seal durable coating is preferably made of a composition mainly comprising a polymer selected from the group consisting of polyvinyl alcohol (PVOH), water dispersible ethylene vinyl alcohol copolymer (EVOH), ethylene vinyl alcohol vinyl acetate copolymer A group consisting of substances, polyvinylidene chloride (PVDC), water-dispersible polyamide (PA), starch, starch derivatives, and combinations of two or more of these substances.

PVOH as a liquid coated barrier polymer has many better properties than aluminum foil and in many cases is the most preferred barrier material. Among these good properties, mention should be made of good film-forming properties, good compatibility with food and economical value, and its high oxygen barrier properties. In particular, PVOH provides a packaging laminate with high odor barrier properties, which is especially important for milk packaging.

As with other conceivable high-temperature melting polymers (e.g., starch or starch derivatives), polyvinyl alcohol can be applied by a liquid coating process (i.e., in the form of a water- or solvent-based dispersion or solution). Suitably coated, in application, the solution is spread to form a thin, uniform layer on the substrate and then dried.

Aqueous systems often have certain environmental advantages. Preferably, the liquid gas barrier composition is water-based, as such compositions are generally more environmentally friendly than solvent-based systems.

To improve the water vapor and oxygen barrier properties of the PVOH coating, polymers or compounds with carboxylic acid functional groups may be included in the composition. Suitably, the carboxylic acid functional polymer is selected from ethylene acrylic acid copolymer (EAA) and ethylene methacrylic acid copolymer (EMAA) or mixtures thereof. One known mixture of this particularly preferred barrier layer consists of PVOH, EAA and inorganic platelet compounds. The EAA copolymer is then added to the barrier layer in an amount of about 1-20% by weight (based on dry coat weight).

It is believed that the improved oxygen and water barrier properties come from the esterification reaction of PVOH and EAA at elevated drying temperature, so that PVOH is cross-linked by hydrophobic EAA polymer chains, so that the EAA polymer The chains are structured into the structure of PVOH. However, this mix is more expensive due to the cost of the additives.

Furthermore, the composition can be made more durable by drying and curing at elevated temperatures. Crosslinking can also be initiated in the presence of polyvalent compounds (eg metal compounds such as metal oxides), although such compounds are less preferred in coating compositions for this purpose.

Specific types of water-dispersible ethylene vinyl alcohol polymers (EVOH) have recently been developed and conceivable liquid coating compositions that can be used as an oxygen barrier. However, conventional EVOH polymers are generally used for extrusion and are not possible to disperse/dissolve in aqueous media to produce thin liquid coating barriers of 5 g/ ^m2 or less (preferably 3.5 g/ ^m2 or less) membrane. It should be understood that EVOH should include a relatively high number of vinyl alcohol monomer units to be water dispersible or soluble, and the properties should be as close as possible to those of liquid coating grades of PVOH. Extruded EVOH layers are not a substitute for EVOH coating liquids, because for extrusion coating, they are inherently less similar to PVOH than for EVOH, and because they cannot be coated by extrusion or extruded Lamination is applied as a single layer in cost-effective amounts below 5 g/m ² , ie it requires co-extrusion of bonded polymer layers, which are typically very expensive polymers. Also, very thin extruded layers cool too quickly and do not contain enough thermal energy to maintain adequate lamination bonds with adjacent layers.

Examples of other polymeric binders suitable for liquid application are polysaccharides, especially starch or starch derivatives, such as preferably oxidized starch, cationic starch and hydroxpropylated starch. Examples of such modified starches are hypochlorite oxidised potato starch (Raisamyl 306 from Raisio), hydroxypropyl cornstarch (Cerestar 05773). However, other starch forms and derivatives may also be viable liquid coating binders.

A further example of a polymeric binder is a coating comprising a mixture of a carboxylic acid containing polymer such as an acrylic or methacrylic polymer and a polyol polymer such as PVOH or starch. As mentioned above, the crosslinking reaction of these polymeric binders is preferred for resistance to high humidity.

Most preferably, however, the binder polymer is PVOH because it has all the good properties mentioned above, namely good film forming properties, gas barrier properties, in addition to good induction heat seal barrier properties. performance, cost-effectiveness, compatibility with food, and odor barrier properties.

PVOH based gas barrier compositions perform well when the PVOH has a degree of saponification of at least 98%, preferably at least 99%, although PVOH with a lower degree of saponification can also provide good performance.

According to one embodiment, in order to further improve the oxygen barrier performance, the liquid composition additionally includes inorganic particles.

For example, a polymeric binder material may be mixed with an inorganic compound, which is in the form of a layer or sheet. With the layered arrangement of sheet-like inorganic particles, oxygen molecules have to travel a longer distance through the oxygen barrier layer via a curved path than the usual straight path across the barrier layer.

According to one embodiment, said inorganic layered compound is a so-called nanoparticulate compound dispersed in an exfoliated state, ie laminates of the layered inorganic compound are separated from each other by a liquid medium. The layered compound is therefore preferably swellable or splittable by means of a polymer dispersion or solution which penetrates into the layered structure of the inorganic material during dispersion. The inorganic material can also be swollen with a solvent before being added to the polymer solution or polymer dispersion. Thus, the inorganic layered compound is dispersed in a delaminated state in the liquid gas barrier composition and the dried barrier layer. The term clay minerals or clay includes the corresponding minerals of kaolinite, antigorite, smectite, vermiculite, bentonite or mica . Specifically, laponite, kaolinite, dickite, nacrite, halloysite, antigorite, chrysotile, Pyrophyllite, montmorillonite, hectorite, saponite, sauconite, sodium tetrasilicic mica, sodium taeniolite Taeniolite, commonmica, margarite, vermiculite, phlogopite, xanthophyllite and the like may be mentioned as suitable clay minerals. Preferred nanoparticles are montmorillonite particles, most preferably purified montmorillonite or sodium-exchanged montmorillonite (Na-MMT) particles. The nanoscale inorganic laminated compound or clay mineral preferably has an aspect ratio of 50-5000 and a particle size with an upper limit of about 5 μm in an exfoliated state.

Preferably, the inorganic microparticles consist essentially of such layered bentonite particles having an aspect ratio of from 50 to 5000.

Suitably, the barrier layer comprises from about 1% to about 40%, preferably from about 1% to about 30%, most preferably from about 5% to about 20%, by dry coating weight The weight of the inorganic layered compound. If the content is too low, the gas barrier properties of the coated and dried barrier layer will not be significantly improved compared to when no inorganic laminar compound is used. If the level is too high, the liquid composition will be more difficult to apply as a coating and more difficult to handle in storage containers and conduits of the applicator system. Preferably, the barrier layer comprises from about 99% to about 60% by weight, more preferably from about 99% to about 70% by weight, most preferably from about 95% to about 80% by weight of the dry coating. % by weight of the polymer. Additives, such as dispersion stabilizers or the like, may be added to the gas barrier composition, preferably not exceeding about 1% by weight of the dry coating.

According to another embodiment, said inorganic particles consist essentially of laminar talcum particles having an aspect ratio from 10 to 500. On a dry basis, the composition generally comprises from 10% to 50% by weight, more preferably from 20% to 40% by weight, of talc particles. Below 20% by weight, there is no significant improvement in gas barrier performance, and above 50% by weight, the coating becomes more brittle and brittle because the cohesion between the particles in the coating is weaker. Small. Above 50% by weight, the level of polymeric binder will be too low to surround and disperse the particles and laminate them to each other in the layer.

Alternatively, good oxygen barrier properties will be obtained when using silica gel particles having a particle size of 3-150 nm, preferably 4-100 nm, even more preferably 5-70 nm, said particles being preferably amorphous and spherical of. The use of silica gel particles also has the advantage that the liquid barrier composition can be used at a dry content of 15%-40% by weight, preferably 20%-35% by weight, more preferably 24%-31% by weight. It is applied when the content is high, thereby reducing the need for forced drying.

Other alternatives to inorganic microparticles that can be used are kaolin clay microparticles, mica microparticles, calcium carbonate microparticles, and the like.

When inorganic particulates are employed to provide oxygen barrier properties, the preferred polymeric binder is PVOH, such as the foregoing, in part because of its advantageous properties mentioned above. In addition, PVOH is also advantageous from a mixing point of view, that is, it is usually easy to disperse or exfoliate inorganic particles in an aqueous solution of PVOH to form a stable mixture of PVOH and particles, which can form a compound with uniform composition and morphology. Good coating film.

Preferably, according to the present invention, the induction heat-sealing durable layer is used in a total amount of from 0.5 to 7 g/m ² , preferably from 0.5 to 5 g/m ² , more preferably 0.5-3 g/m ² (by dry weight count) is coated. Below 0.5g/ ^m2 , the effect on the durability of the induction seal will be low, and if the coated layer is too thin, the coating will be dried depending on the nature of the paper or substrate, and removal of water or solvent The barrier layer, will lead to the risk of forming pinholes. On the other hand, above 7 g/m ² the coating will not make the packaging laminate cost-effective due to the generally high cost of polymers and due to the high energy costs of evaporating the dispersion liquid.

In addition, recognizable levels of oxygen barrier layers can be obtained by PVOH coating at 0.5 g/ ^m2 and above, and a comparison between barrier performance and cost can be obtained between 0.5 ^g / ^m2 and 3.5 g/m2. nice balance.

According to one embodiment of the invention, the oxygen barrier layer is applied in two consecutive steps with drying between the two steps to obtain two part-layers. If applied in this manner in two layers, each layer is suitably applied in an amount from 0.3 ^g / ^m2 to 3.5 g/m2, preferably from 0.5 g/m2 to ^2.5 g/m2 ² , and a higher quality total layer can be obtained from a lower amount of liquid gas barrier composition. More preferably, the two part-layers are each applied in an amount of from 0.5 g/m ² to 2 g/m ² , preferably each in an amount of from 0.5 g/m ² to 1.5 g/m ² .

The metal vapor deposition coating is applied to a thin coated paper substrate by physical vapor deposition (PVD). The thin metal vapor deposited coating according to the invention has a thickness on the nanoscale, i.e. has a thickness most suitably measured in nanometers, for example from 5 to 500 nm Preferably from 5 to 200 nm, more preferably from 5 to 100 nm, most preferably from 5 to 50 nm.

Typically, below 5 nm, the induction heat seal durability is too low to be usable, while above 200 nm, the coating is less elastic and results in greater susceptibility to cracking when applied to elastic substrates.

Typically, such vapor deposited coatings with induction heat durability are made of metal compounds, and preferably, the induction heat seal causing the metal vapor deposited coating is a layer substantially made of aluminium. Typically, due to the nature of the metallization process used, the aluminized layer essentially has a thin surface portion consisting of aluminum oxide.

Suitably, said metal vapor deposited coating has an optical density (OD) of from 1-5, preferably from 1.5-3.5, more preferably from 2-3.

The aluminum-based thin vapor-deposited layer preferably has a thickness of 5-100 nm, more preferably 5-50 nm, which is less than 1% of the aluminum metal material in aluminum foils of conventional thickness (ie 6.3 μm).

In order to improve the adhesion of the coating to the substrate, a surface treatment step of the substrate film can be carried out prior to the vapor deposition coating of the substrate, in particular the metallization of the substrate.

The preferred metal according to the invention is aluminium, although any other metal which can be vacuum deposited to a uniform coating can also be used according to the invention. Secondary and rare metals such as Au, Ag, Cr, Zn, Ti or Cu are therefore also conceivable. Generally, thin coatings of metals or mixtures of metals and metal oxides provide water vapor barrier properties and can also be used when the desired function is to prevent water vapor migration through multilayer films or packaging laminates The metal thin coating or thin coating of a mixture of metal and metal oxide. Most commonly, however, the metal in the metallization is aluminum (Al).

In order to make the metal vapor deposition coating process cost-effective, the substrate (i.e. the innermost first paper or other cellulose-based layer (11)) should be as thin as possible in order to be as long as possible. The coated paper can be rolled onto a coated paper roll. Preferably, said first paper layer has a surface weight of from 20 to 100 g/m ² , preferably from 20 to 70 g/m ² , more preferably from 30-60 g/m ² . When the paper is too thin, it will naturally be more difficult to handle in subsequent coating and lamination processes. On the other hand, the thinner the paper, the more cost-effective this metal vapor deposition coating process will be. From a rigidity standpoint, the thicker first paper layer also makes the overall packaging laminate structure more rigid and grippable.

The second paper or paperboard layer used as a stabilizing layer in common cardboard packages for liquid packaging generally has a thickness of from about 100 μm to about 600 μm, and about 100-500 g/m ² , preferably about 200-400 g/m ² , more preferably from 200-300 g/ ^m2 surface weight and may be conventional paper or paperboard of suitable packaging quality.

On the other hand, for inexpensive aseptic, long-term packaging of liquid foods, thinner packaging laminates with thinner paper layers can be used. Packaging containers made with this packaging laminate are not folded to shape and more closely resemble a pillow-shaped elastic bag. Suitable single paper layers for such bag packaging generally have from about 30 to about 140 g/m ² , preferably from about 50 to about 120 g/m ² , more preferably from 50 to about 110 g/m ² , most preferably from Surface weight of about 50 to 70 g/m ² .

According to one embodiment, this inexpensive packaging laminate may alternatively comprise two or more tissue layers, wherein, according to the invention, the first inner paper layer is coated by vapor deposition of an inductively thermosensitive material. When there are two layers of paper in the packaging laminate structure, the second outer paper layer suitably has a weight of from 20-100 g/ ^m2 , preferably from 20-70 g/ ^m2 , more preferably from 20-50 g/ ^m2 surface weight.

In order to further improve the properties of foil-free packaging laminates, an oriented film is applied on the metallized layer (metal vapor deposited layer). The use of oriented films provides beneficial barrier properties. The application of the film can reduce the cost of the final package and improve or replace its performance. The film also acts as a protective layer for the metallization layer during lamination, reducing the risk of chipping or pinholes. Suitable films are oriented films stretched in at least one direction with a draw ratio of 2 or more and having a core layer of material with a higher melting point than the heat-sealable material of the innermost layer of the packaging laminate. Generally, the melting point of the core layer is above 130°C. The stretch ratio depends on the materials used in the film and can be as high as about 10. In certain aspects of the invention, it is preferred to have a stretch ratio of 3 or higher. Examples of suitable films are mono-oriented films having at least a core layer consisting of a polymer material selected from the group consisting of polypropylene (OPP), polyethylene terephthalate ( OPET), polyamide (OPA), polyethylene naphthalate (OPEN), polybutylene terephthalate (OPBT), trimethylene terephthalate (OPTT); biaxially oriented film (biaxially -oriented films), such as biaxially oriented polypropylene (BOPP), polyethylene terephthalate (BOPET), polyamide (BOPA), polyethylene naphthalate (BOPEN), polyethylene terephthalate Butylene dicarboxylate (BOPBT), propylene terephthalate (BOPTT), or made of said polymers (i.e. polypropylene, polyethylene terephthalate, polyamide, polyethylene naphthalate Oriented films of two or more formed from glycol esters, polybutylene terephthalate, propylene terephthalate), said polymers being mixed or copolymerized and thereafter used for single or biaxial orientation oriented film. Some of the beneficial properties of the films are high tensile strength for high speed transitions, good resistance to puncture and flex cracking over a wide temperature range, potentially good barrier to moisture, resistance to oils and greases As well as moisture resistance, there is also resistance to wrinkling or shrinking due to changing environmental conditions.

The orientation film may be a film comprising additional layers, in which case the core layer of the film is represented by the films exemplified above. In certain aspects of the invention, the core layer of the film is a polymer selected from the group consisting of mono-oriented polypropylene (OPP), polyethylene terephthalate (OPET), polyethylene Amide (OPA), polyethylene naphthalate (OPEN), polybutylene terephthalate (OPBT), trimethylene terephthalate (OPTT); biaxially-oriented poly Propylene (BOPP), Polyethylene Terephthalate (BOPET), Polyamide (BOPA), Polyethylene Naphthalate (BOPEN), Polybutylene Terephthalate (BOPBT), Terephthalate Propylene glycol phthalate (BOPTT).

The film may additionally comprise one or more of the following: a tie layer, an adhesive layer, and a liquid-tight heat-seal layer. Tie layers are used to facilitate bonding between prefabricated rolls or films and typically consist of thermoplastic polymers. The adhesive layer is used to improve the adhesion between the film and other layers and generally consists of an adhesive polymer containing adhesion promoting functional groups.

According to the invention, the adhesive layer is a layer of the oriented film. The adhesive layer can be applied before stretching, for example by coextrusion with the core layer, or after stretching, for example by dispersion coating. This adhesive polymer layer on the outside of the oriented film achieves lamination by applying heat and pressure in the roll nip of the lamination station when bonding the oriented film and the coated paper web, without the need for two An additional intermediate bonding layer is extruded between the prefabricated rolls.

The thickness of the alignment film is usually between 4 and 25 μm. This generally applies when the film does not include a liquid-tight heat-seal innermost layer, since the film would be thicker if it were.

In certain embodiments of the invention, the film itself has no adhesive layer in it, but the film is bonded to the metallization layer by a separate adhesive layer, typically by placing the preformed film layer Application is made by extrusion laminating an intermediate melt extrusion layer when pressed to a precoated, metallized paper layer.

In certain embodiments of the invention, both an adhesive layer as part of the oriented film and an intermediate tie layer are present and used to laminate the oriented film to the metallized paper.

Alternative examples of materials suitable as tie layers for extrusion lamination layers are polymers based on low density polyethylene type polymers and selected from modified or unmodified LDPE or LLDPE polymers, having Copolymers or graft copolymers of vinyl polymers with functional groups (such as carboxyl or glycidyl functional groups) of monomer units, for example, (meth)acrylic acid monomers or maleic anhydride (MAH) monomers can be used , (ie, ethylene acrylic acid copolymer (EAA) or ethylene methacrylic acid copolymer (EMAA)), ethylene-glycidyl (meth)acrylate copolymer (EG(M)A) or maleic anhydride - Grafted polyethylene (MAH-g-PE). Another example of such modifying or binding polymers are so-called ionomers based on low-density polyethylene. In one embodiment, the modified polyethylene is ethylene acrylic acid copolymer (EAA) or ethylene methacrylic acid copolymer (EMAA).

In some respects it may be advantageous to use LDPE or LLDPE as the tie layer.

Examples of adhesive layers are carboxylic acid-functionalized polyethylenes based on LDPE or LLDPE including copolymers or graft copolymers with functional groups comprising monomeric units, such as carboxyl or glycidyl functional groups, for example, ( Meth)acrylic acid monomer or maleic anhydride (MAH) monomer, (i.e., ethylene acrylic acid copolymer (EAA) or ethylene methacrylic acid copolymer (EMAA)), ethylene-glycidyl (methyl) Acrylate copolymer (EG(M)A) or MAH-grafted polyethylene (MAH-g-PE). Another example of such modified or binding polymers are so-called ionomers or ionomer polymers. Preferably, the adhesive layer is selected from the group consisting of ethylene acrylic acid copolymer (EAA), ethylene methacrylic acid copolymer (EMAA), ethylene-glycidyl (meth)acrylate copolymer (EG(M)A) and butadiene Alkenedic anhydride-grafted polyethylene (MAH-g-PE), preferably ethylene acrylic acid copolymer (EAA) or ethylene methacrylic acid copolymer (EMAA). The adhesive layer may be included in the film by any conventional technique such as dispersion coating and subsequent drying on the core substrate layer of the film or coextrusion coating of an adhesive layer on the core layer.

One or more liquid-tight heat-sealable layers are required as the innermost part of the packaging material which is in direct contact with the product filled in the packaging container made from the packaging material. The liquid-tight heat-sealable layer included in the oriented film may be an optional or complementary layer to provide a separate innermost liquid-tight heat-sealable layer. The term liquid-tight heat-seal layer generally refers to a layer of an oriented film. The liquid-tight heat-sealable layer is selected from the same type of polyolefins as the outermost and innermost liquid-tight heat-sealable layers. Suitable thermoplastics for the liquid-tight heat-sealable layer and for the liquid-tight heat-sealable layers of the outermost and innermost layers are based on polyolefins such as polyethylene or polypropylene, preferably polyethylene, More preferably low density polyethylene such as LDPE, linear LDPE (LLDPE) or single site metallocene catalyzed polyethylene (m-LLDPE), very low density linear polyethylene (vLLDPE) or a combination of two or more of these mixture. Such liquid-tight heat-sealable layers are often used and may additionally comprise an adhesive layer to provide improved adhesion to the core layer of the oriented film. Thus, the adhesive layer may be applied on the inner side of the oriented film as a coextruded part of the innermost layer of liquid-tight heat-sealable thermoplastic polymer material. Furthermore, the innermost layer of liquid-tight heat-sealable thermoplastic material is often strictly sterile.

The vapor deposited metal coated first paper layer may be bonded to the second paper or paperboard layer by one or more intermediate polymer layers, such as thermoplastic polymer layers, more preferably selected Polymer layers from polyolefins and polyolefin-based copolymers, also commonly known as modified or adhesive polymers, in particular LDPE as described in the paragraph above Either polyvinyl polymers or copolymers, or adhesive polymers.

According to the invention, in order to further increase the light-blocking capability of the packaging laminate, if necessary, particles or pigments providing light-blocking properties may be mixed into one or more layers of the laminate. An example is light absorbing particles such as carbon black. The black color of the intermediate layer is then advantageously concealed towards the outside by a paper or cardboard layer and towards the inside of the laminate by a metallized (for example aluminium) layer. Another example is light reflective particles such as titanium dioxide. Such particles can further be added to the whiter exterior of the packaging laminate.

For thinner inexpensive segment packaging laminates with thinner paper core layers, this light reflective inorganic white colorant improves the light blocking properties of the packaging laminate and improves the outward facing appearance of the packaging material.

For higher performance packaging laminates, e.g. for more sensitive products requiring longer aseptic shelf life, further barrier layers can of course be added. For example, a simple way to further increase the oxygen barrier properties of a packaging laminate could be to use a thermoplastic bonding layer comprising a melt-extrudable barrier layer to bond the metal vapor deposition coated inner first paper layer to the A further, second paper or cardboard layer. According to this example, the only thing that needs to be changed to produce a higher performance packaging laminate is the inclusion of an additional layer of melt extruded polymer (e.g. a further barrier layer and possibly One or two coextruded tie layers). According to another more preferred embodiment, a thin layer of barrier polymer may be co-extrusion coated onto the metal-clad inner side of said first paper layer together with an optional tie layer and an innermost heat-sealable layer. This coextruded inner barrier layer needs to be kept relatively thin in order to easily transfer the induced heat from the metal vapor deposited layer to the heat sealable layer.

Alternatively, a liquid film oxygen barrier coating may be applied to the innermost first paper layer on the other outer side, alternatively or additionally a liquid film oxygen barrier coating may be applied within the packaging laminate structure the inside of any further paper layers.

According to another aspect of the present invention, there is provided a packaging container made of the aluminum foil-free packaging laminate of the present invention. The packaging container is suitable for long-term, aseptic packaging of liquid food or food containing water, and it has a high-quality packaging integrity derived from a high-strength, durable seal of induction heat sealing.

According to still another aspect of the present invention, there is provided a method for manufacturing a packaging laminate as defined in the independent method claim.

Accordingly, the method comprises the steps of: providing at least a first layer of paper or other fiber-based material, applying an induction-sealable durable layer to the inner side of said paper or fiber-based material layer against said paper or fiber-based material layer. The layer of material is pre-coated to receive and support an induction thermosensitive metal vapor deposition coating, said induction thermosensitive metal layer is applied to the inner side of the coated paper layer, an orientation film is provided and the orientation film is laminated to Paper layer coated with metal. As mentioned above, the film itself may comprise a liquid-tight heat-seal layer representing the innermost layer of the film, and optionally an adhesive layer representing one side of the film applied to the inductive heat sensitive metal layer.

In one embodiment, the method includes applying an intermediate adhesive layer between the inductively thermosensitive metal layer and the alignment film.

At any stage of the process, an outermost layer of heat-sealable thermoplastic polymer material may be provided and laminated to the opposite outermost layer of the packaging laminate. In case the packaging laminate structure comprises a second paper layer arranged towards the outside of the packaging laminate, the outermost heat-sealable polymer layer is then laminated to the outside of said second paper layer.

The inductively thermosensitive metal layer is itself sufficiently uniform and continuous to conduct electrical current under the action of an inductive magnetic field and become heated such that the thermoplastic polymer layer is heated and melted to provide a melt seal of said polymer. If the metal layer is discontinuous due to uneven coating or due to cracks, no heating will occur in the sealing area.

During the precoating of said metal receiving layer, the method further comprises the steps of providing a liquid composition comprising a polymeric binder dispersed or dissolved in a water-based or solvent-based liquid medium, and by said A liquid composition is applied to the inside of the paper or other fiber-based material layer and then dried to evaporate the liquid to form a thin film adjacent to the inside of the first paper layer and containing the polymeric binder. An induction-sealable durable layer of an induction-sealable polymeric binder having a higher melting point than the thermoplastic polymeric material of the innermost heat-sealable layer.

Preferably, said induction heat seal durable polymer comprised in the liquid composition is selected from the group consisting of polyvinyl alcohol (PVOH), water dispersible ethylene vinyl alcohol copolymer (EVOH), ethylene vinyl alcohol vinyl acetate copolymer, polyvinylidene Group consisting of vinylidene chloride (PVDC), water dispersible polyamide (PA), starch, starch derivatives and mixtures of two or more of these substances.

According to one embodiment, the induction sealing durable layer (12) is coated in a total amount of from 0.5 to 7 g/m ² , preferably from 0.5 to 5 g/m ² , more preferably from 0.5 to 3 g/m ² , by dry weight.

If applied in two layers, each layer may suitably be applied in an amount from 0.3 to 3.5 g/m ² , preferably from 0.5 to 2.5 g/m ² , which enables a relatively low amount of liquid polymer composition Produces a higher quality total layer. More preferably, each of the two layers may be applied in an amount of from 0.5 to 2 g/m ² , preferably in an amount of from 0.5 to 1.5 g/m ² respectively.

In order to reduce the amount of moisture released from the paper layer to the vacuum chamber during the metallization process, the first paper layer to be coated by metal vapor deposition can also be placed on the other side before the metallization process step. The outside is coated with the polymer liquid component in a water-based or solvent-based dispersion or solution. For metallization, it is desirable to keep the vacuum chamber free of moisture, since the presence of moisture will slow down the speed at which the metallization process is carried out.

Also any back transfer of paper dust in subsequent processing of the coated paper webs on the reel can be prevented by the coating on the rear side.

For food products that require better barrier properties to oxygen, a gas barrier coating may be applied to the outside of the first paper layer.

In cases where the packaging laminate structure comprises a second paper layer disposed towards the outside of the packaging laminate, the gas barrier coating may also be applied to the inside of said second paper layer.

In case the packaging laminate structure comprises a second paper layer disposed towards the outside of the packaging laminate, the method of the invention further comprises passing through an intermediate polymeric adhesive layer (preferably a thermoplastic polymeric adhesive layer) A step of extrusion laminating a vapor deposited tissue paper substrate to the inside of said second paper layer.

A further aspect of the present invention is a method of heat sealing a foilless packaging laminate comprising the steps of providing a foilless packaging laminate as defined above in continuous web form, the web form The packaging laminate is formed into a continuous tubular shape and longitudinally sealed in the longitudinal direction, and the liquid food is filled into the packaging laminate tube by induction heating at predetermined intervals in the transverse direction of the filled tube body. Heat seal areas are formed and cut from the center of each transverse seal area to form individual containers.

In order to further describe the present invention, reference will be made to the accompanying discussions.

In FIG. 1 a a first embodiment of a packaging laminate produced according to the invention for aseptic packaging and long-term storage under ambient conditions is shown in a cross-sectional view. The laminate comprises a first paper layer 11 having a surface weight of 50 g/m ² .

The paper is prepared to receive a metal vapor deposited coating 12 capable of acting as an inductive thermosensitive material and transferring heat to effect a heat seal in the innermost oriented film 20 .

The tissue to be subsequently coated by metal vapor deposition can be prepared by coating or by impregnating the paper layer or by mixing chemicals into the pulp at the production stage of the roll paper or by any combination of these or other methods .

The prepared tissue was then vapor deposited metal to an optical density (OD) of about 3.

The liquid-tight and heat-sealable polyolefin layer 15 of the outer layer is applied on the outside of the core layer 11, which side will be facing the outside of the packaging container produced from the packaging laminate. The polyolefin of the outer layer 15 may be conventional low density polyethylene (LDPE) having heat sealable qualities. The orientation film 20 is laminated on the inside of the vapor deposition layer 12 facing the inside of the packaging container made of the packaging laminate, and the orientation film 20 will be in contact with the packaged product. The core layer of the oriented film is preferably selected from mono-oriented films such as polypropylene (OPP), polyethylene terephthalate (OPET), polyamide (OPA), polyethylene naphthalate Diol ester (OPEN), polybutylene terephthalate (OPBT), propylene terephthalate (OPTT); biaxially-oriented films, such as biaxially-oriented polypropylene (BOPP ), polyethylene terephthalate (BOPET), polyamide (BOPA), polyethylene naphthalate (BOPEN), polybutylene terephthalate (BOPBT), terephthalic acid Propylene glycol ester (BOPTT), or made of said polymers (i.e. polypropylene, polyethylene terephthalate, polyamide, polyethylene naphthalate, polybutylene terephthalate, propylene terephthalate), said polymers are mixed or copolymerized and thereafter used to form a single or biaxially oriented film.

In some embodiments, such as disclosed in FIGS. 1 a , 1 b and 1 c , the oriented film includes one or more liquid-tight heat-seal layers that represent the innermost side of the oriented film and thus will communicate with the Contact with packaged product. The liquid-tight heat-seal layer representing the innermost part of the film is a liquid-tight, heat-sealable thermoplastic polymer material, such as a polymer based on low density polyethylene, such as LDPE and/or LLDPE. In one embodiment, the low density polyethylene comprises the process of combining ethylene monomers with C4-C8 (more preferably C6- C8) LLDPE produced by polymerization of α-olefin alkylene monomer. The alignment film 20 may additionally include an adhesive layer on its outer side to be laminated to the metal vapor deposition layer 12 .

In one embodiment, similar to the embodiment disclosed in FIG. 1 a , as shown in cross section in FIG. 1 a 2 , an oriented film is laminated on the inner side of the vapor deposited layer 12 , which is directed towards the The inside of the packaging container. An innermost liquid-tight and heat-sealable thermoplastic polymer material 14 , such as low density polyethylene such as LDPE and/or LLDPE, is provided on the inner side of the oriented film 20 . In one embodiment, the low density polyethylene comprises the process of combining ethylene monomers with C4-C8 (more preferably C6- C8) LLDPE produced by polymerization of α-olefin alkylene monomer. The innermost heat-sealable layer 14 may consist of two or several layers of the same or different types of polymers. In an embodiment disclosed in Figure 1a2, the oriented film (20) may or may not comprise a liquid-tight heat-seal layer representing the layer of the film towards the inside, on the opposite face of the film is the vapor-deposited layer 12. It is often preferred to have only one liquid-tight heat-sealable layer, especially for cost reasons. However, it is also possible to use two heat-sealable layers, one of which acts as the liquid-tight heat-sealable layer of the oriented film and the other as the liquid-tight heat-sealable thermoplastic polymer material 14 .

Throughout this specification, it applies that whenever an innermost liquid-tight heat-sealable layer 14 is present, the liquid-tight heat-sealable layer of the film may or may not be present.

In some embodiments of the invention, such as those disclosed in the figures, the alignment film 20 is bonded to the metal vapor deposited layer by an adhesive layer such as ethylene acrylic acid copolymer. The adhesive layer is a layer of an oriented film. Alternatively or complementary, an adhesive layer 19 may be applied as an intermediate layer between the oriented film and the metallized paper layer. Suitable tie layers are based on polymers of the low density polyethylene type and are selected from modified or unmodified LDPE or LLDPE polymers, ethylene with functional groups comprising monomeric units (e.g. carboxyl or glycidyl functional groups) Polymer-like copolymers or graft copolymers, for example, (meth)acrylic acid monomers or maleic anhydride (MAH) monomers can be used, (i.e., ethylene acrylic acid copolymer (EAA) or ethylene methacrylic acid copolymer (EMAA)), ethylene-glycidyl (meth)acrylate copolymer (EG(M)A) or maleic anhydride-grafted polyethylene (MAH-g-PE). Another example of such modifying or binding polymers are so-called ionomers based on low-density polyethylene. In one embodiment, the modified polyethylene is ethylene acrylic acid copolymer (EAA) or ethylene methacrylic acid copolymer (EMAA). The modified polymer may also be suitable for use in an optional adhesive layer included in the film.

In special cases, when a thicker heat-sealable layer is required, it is of course possible (though not preferred from a cost point of view) to apply a further layer of liquid-tight heat-sealable polyethylene to the inside of the innermost layer 14 .

In FIG. 1 b a second embodiment of a packaging laminate produced according to the invention for aseptic packaging and long-term storage at room temperature is shown in a cross-sectional view. The laminate comprises a first paper layer 11 having a surface weight of 50 g/m ² and a thin induction-seal durable layer formed by liquid coating a liquid polymer composition onto the paper layer 11 followed by drying 13. The composition includes an aqueous solution of PVOH, and after drying, the coating includes PVOH. Preferably, the PVOH has a saponification degree of at least 99%.

The coated tissue was then vapor-deposited metal to an optical density (OD) of about 3 on the coated side. The resulting packaging laminate consisted of a tissue paper substrate 11 covered first with PVOH and then with a thin vapor deposited coating 12 of aluminum metal about 50 nm thick. The innermost oriented film 20 is bonded to the metal vapor deposited layer (as shown in FIG. 1b3 ) by means of an adhesive layer and/or tie layer 19, on the inner side of the vapor deposited layer 12, which faces from the packaging lamination The inner side of the packaging container made of material, and the orientation film 20 will be in contact with the packaged product. The core layer of the oriented film is preferably selected from biaxially oriented polymer layers.

In one embodiment, similar to the embodiment disclosed in FIG. 1b , as shown in cross-section in FIGS. 1b2 and 1b4 , the oriented film is passed through an adhesive layer ( FIG. 19 ( FIG. 1b4 ) is bonded to the inside of the vapor deposited layer 12 . An innermost liquid-tight and heat-sealable low-density polyethylene (such as LDPE and/or LLDPE) thermoplastic polymer material 14 is disposed on the inside of an oriented film 20 (which may or may not include a liquid-tight heat-seal layer) superior. In one embodiment, the low density polyethylene comprises the process of combining ethylene monomers with C4-C8 (more preferably C6- C8) LLDPE produced by polymerization of α-olefin alkylene monomer. The innermost heat-sealable layer 14 may consist of two or several layers of the same or different types of polymers. In one embodiment, the innermost liquid-tight heat-sealable layer 14 additionally comprises an adhesive layer in order to improve the bonding between the liquid-tight heat-sealable layer 14 and the oriented film 20 . In another similar embodiment, the oriented film comprises an adhesive layer on its inner side, onto which the liquid-tight heat-sealable layer 14 is laminated or co-extruded.

In special cases, when a thicker heat-sealable layer is required, it is of course possible (though not preferred from a cost point of view) to apply a further layer of heat-sealable polyethylene to the inner side of the innermost layer 14 .

The liquid-tight and heat-sealable polyolefin layer 15 of the outer layer is applied on the outside of the core layer 11, which side will be facing the outside of the packaging container produced from the packaging laminate. The polyolefin of the outer layer 15 may be conventional low density polyethylene, such as LDPE and/or LLDPE of suitable heat-sealable quality.

In FIG. 1 c , an example of a packaging laminate 10 c produced according to the invention for aseptic packaging and long-term storage at room temperature is shown in a cross-sectional view. The laminate comprises a first paper layer 11 having a surface weight of 50 g/m ² and a thin induction-seal durable layer formed by liquid coating a liquid polymer composition onto the paper layer 11 followed by drying 13. The composition comprises PVOH and 30% by weight of an aqueous solution of bentonite particles, and after drying, the coating comprises PVOH and optionally exfoliated bentonite particles uniformly distributed in layered form in the PVOH layer. Preferably, the PVOH has a saponification degree of at least 99%.

The prepared tissue was subsequently metallized by vapor deposition to an optical density (OD) of about 3.

The resulting packaging laminate consisted of a tissue paper substrate 11 which was first covered with PVOH and then with a thin vapor deposited coating 12 of aluminum metal about 50 nm thick.

Furthermore, the packaging laminate comprises a second core, paperboard layer 16 having a surface weight of at least 200 g/m ² or preferably about 300 g/m ² . The first and second paper layers are suitably bonded to each other via the intermediate layer 17 . The intermediate layer is usually based on polyolefin based polymers, preferably low density polyethylene (LDPE). The intermediate adhesive layer 17 is preferably formed by mutual extrusion lamination of a first metal-coated paper layer and a second cardboard layer. The intermediate layer 17 may be one or more layers.

The outer liquid-tight and heat-sealable layer 15 is as defined in Figures 1a and 1b.

In one embodiment, similar to the embodiment disclosed in FIG. 1c, as shown in the cross-section in FIG. 1c2, the orientation film is bonded to the inner side of the vapor deposition layer 12 through a thin induction sealing durable layer 13, and the induction sealing is durable. Layer 13 is formed by liquid coating a liquid polymer composition onto paper layer 11 followed by drying. Between the vapor deposition layer 12 and the alignment film 20 , an adhesive layer as a part of the film 20 is laminated to the vapor deposition layer 12 . An innermost liquid-tight and heat-sealable thermoplastic polymer material 14 is provided on the inner side of the oriented film 20 . In this embodiment, the low density polyethylene comprises the process of combining ethylene monomers with C4-C8 (more preferably C6- C8) LLDPE produced by polymerization of α-olefin alkylene monomer. The innermost heat-sealable layer 14 may consist of two or several layers of the same or different types of polymers. As described above for Figure 1b2, the innermost liquid-tight heat-sealable layer 14 may additionally comprise an adhesive layer, or the oriented film may comprise an adhesive layer on its inner side, to which the liquid-tight heat-sealable layer 14 will be laminated. on the adhesive layer.

As another undisclosed embodiment, similar to the one disclosed in FIGS. 1c and 1c2 , but there may be a bond between the vapor deposited layer 12 and the alignment film 20 as described for FIGS. 1b3 and 1b4 layer.

In special cases, when a thicker heat-sealable layer is required, it is of course possible (though not preferred from a cost point of view) to apply a further layer of heat-sealable polyethylene to the inner side of the innermost layer 14 .

In order to reduce the amount of moisture released from the paper layer to the vacuum chamber during the metallization process, the first paper layer to be coated by metal vapor deposition can also be placed on the other side before the metallization process step. The outside is coated with a polymer liquid composition in a water-based or solvent-based dispersion or solution. For metallization, it is desirable to keep the vacuum chamber free of moisture, since the presence of moisture will slow down the speed at which the metallization process is carried out. Furthermore, any carryback of paper dust in the subsequent processing of the coated paper web on the reel can be prevented.

According to Figures 1a and 1b, this first paper layer 11 may be a thin paper layer of about 50 g/m ² or even less. Since the paper layers are very thin, additional light blocking properties are required, ie enhanced by the addition of pigments in one or more of the layers of the laminate. For example, a light-reflecting white pigment, such as titanium dioxide (TiO2), and/or a light-absorbing pigment, such as carbon black, may be added to a liquid-coated induction heat-seal durable layer 13 such as PVOH. This pigment is advantageously concealed towards the inside by the metal vapor deposition coating 12 and at least to some extent towards the outside by the paper layer 11 .

In Figure 2, a method for liquid application of a polymer composition to a paper or board ply is schematically shown. The paper layer 21a is fed from a storage reel to a liquid coating station where the liquid polymer composition is coated in an amount such that when the coated paper passes through the drying station, the coated The amount of the layer of 22a and dry 22b is about 1-3 g/m ² . Preferably, the liquid coating operation is carried out in two steps, that is, first coating at 0.5-1.5 g/m ² and drying in an intermediate step, followed by a second coating at 0.5-1.5 g/m ² Secondary coating, and finally the total liquid coating layer is dried to obtain the coated paper layer 21b.

FIG. 3 is a diagrammatic view of an example of an apparatus for vapor deposition coating a metal layer 12 onto the coated thin first paper layer produced in FIG. 2 . The thin web 21b from FIG. 2 is subjected to evaporative deposition 30 of a continuous aluminum layer (possibly in a mixture with aluminum oxide) on the coating receiving side, and this coating has a thickness of 5-100 nm, preferably 5-50 nm, whereby A metal-clad paper 34a of the present invention is formed. The aluminum vapor comes from a solid flake evaporation source 31 .

In Fig. 4a a lamination process 40a is shown wherein an induction heat seal durable and/or oxygen barrier covered paper layer 34a further covered by a thin metal vapor deposited coating 21b is thermally laminated to an oriented film 50, The oriented film 50 has an adhesive layer 50a on the side facing the metallization layer, and the innermost heat-sealable LDPE and/or LLDPE layer 14, 43b is extrusion coated onto the inner side of the oriented film 50 and rolled region 45b are pressed together. The laminated paper and film then passes through a second extruder 47 and a lamination nip 48 with an outermost heat sealable layer 46 of LDPE covered to the outside of the paper layer. Finally, the finished packaging laminate 49b is rolled onto a storage reel (not shown).

In Figure 4b, an alternative embodiment is shown in which an induction heat seal durable and/or oxygen barrier coated paper layer 34a is further coated with a thin metal vapor deposited coating 21b at the first lamination station is extrusion laminated to the oriented film 50 together with the tie layer 50b, and is then extrusion coated with the outermost polymer layer 46 at a second extrusion coating station and pressed in the roll nip 45c Together. Subsequently, the laminated paper and film pass through a third extrusion lamination station 48 , wherein the innermost heat-sealable LDPE and/or LLDPE layer 14 , 43 b is applied onto the inner side of the film 50 . Finally, the finished packaging laminate 49c is rolled onto a storage reel (not shown).

As an alternative, packaging laminates are possible that include an additional second paperboard layer with an interlayer of polyolefin-based polymer, preferably low density polyethylene (LDPE), passed through an extrusion layer. The metal coated first paper layer and the second paper layer were pressed and then bonded to the metal coated first paper board following the steps shown in Figures 4a and 4b respectively.

Figure 5a shows an alternative example of a packaging container 50 produced from packaging laminate 10c according to the invention. The packaging container is particularly suitable for drinks, sauces, soups or the like. Typically, such packages have a capacity of about 100-1000 ml. The package may be of any shape, but is preferably brick-shaped, with longitudinal and transverse seals 51 and 52 respectively and, optionally, opening means 53 . In another embodiment (not shown), the packaging container may be wedge-shaped. To obtain this "wedge shape", only the bottom of the package is folded into shape so that the transverse heat seal of the bottom is hidden under triangular corner flaps which are folded and seal the bottom of the package. The top transverse seal is not folded. In this way, the half-folded packaging container is still easy to handle and dimensionally stable when placed on a food store shelf or on a table or the like.

Figure 5b shows an alternative example of a packaging container 50b produced from a packaging laminate according to the invention. With a thinner paper core layer, the packaging laminate is thinner and therefore not dimensionally stable enough to form parallel tubular or wedge-shaped packaging containers without folding after transverse sealing 52b. Therefore, the packaging container is a pillow-shaped bag-like container and is distributed and sold as such.

Figure 6 shows the principle described in the introductory part of the invention, namely that a web of packaging material is formed into a tube 61 by interconnecting the longitudinal edges 62, 62' of the web at overlapping longitudinal junctions 63. The tube is filled 64 with the desired liquid food product and divided into individual packages by repeated transversal sealing 65 of the tube at predetermined mutually spaced distances below the liquid level of the food filled in the tube. The package 66 is separated by cutting on the transversal seal and the package is given the desired geometry by a folding forming operation along prepared fold lines on the material.

The invention is not limited to the embodiments shown and described above but may vary within the scope of the claims.

example

Example 1

Preparation of aqueous coating composition for induction heat sealing durable layer: an aqueous dispersion of exfoliated layered montmorillonite particles (Kunipia F from Kunimine Kogyo Company) having an aspect ratio of about 50-5000 ( aqueous dispersion) is mixed with an aqueous solution of about 30% by weight of PVOH (Mowiol 15-99, having a degree of saponification above 99%) at 60-90° C. for 1-8 hours. The dispersion of exfoliated layered mineral particles can be stabilized by stabilizer additives. Alternatively, the layered mineral particles are directly exfoliated in a PVOH solution at 60-90° C. for 1-8 hours.

Aqueous compositions of water-dissolving and dispersing PVOH and 30% by weight of exfoliated bentonite clay were applied by liquid coating in two consecutive steps with a drying step in between, onto a tissue paper with 50 g/m ² surface weight, of which there is a total of 3g/m ² of PVOH coating. The applied wet coating is dried with hot air to evaporate the moisture.

In a subsequent step, the PVOH-coated paper was coated with an aluminum metal coating on the PVOH layer until an optical density of 3 by a vapor deposition process.

The metallized, PVOH-coated paper is laminated to a 260mN (approximately 270g/m2) cardboard through a low-density polyethylene (LDPE) extrusion lamination thermoplastic adhesive layer. The paper is then coated on the outermost side with a thermoplastic heat-sealable layer (LDPE).

The inner side of the laminated interlayer paper was coated by extrusion laminating a BOPP film using LDPE as an adhesive layer to the inner side. An innermost liquid-tight heat-sealable LDPE layer is applied to the inside of the BOPP film by extrusion coating.

The resulting laminated products are used and in Tetra Brik Heat-sealing quality testing is performed on a conventional filling machine that employs conditioned induction heat sealing of the packaging containers produced. For example, it has been found that in order to achieve sufficient heating efficiency with very thin metallization layers, the frequency used in the induction sealing process needs to be significantly increased.

The appearance and characteristics of the seal portion of the filled and sealed packaging container were studied by tearing the seal portion apart. Observe this appearance and compare it to the sample. The width of the seal and the uniformity of alignment were determined and compared by further testing in which all of the packaging material around the sealed portion was dissolved except the heat-sealed thermoplastic. Finally, the package integrity of the filled and sealed packaging containers is tested using a red ink test. These are the dairy and filling stations to Tetra Brik All known tests are carried out on the packaging of the packaging for daily production, filled packaging container seal quality control.

The performance and quality of the sealed packaging container samples were compared to Tetra Aseptic packaging containers were evaluated on the basis of many years of experience in quality control of conventional packaging laminates.

The heat seal quality and integrity of the produced packaging was excellent and on par with today's Tetra Brik Aseptic, foil-based packaging, as evaluated by the passing test panel. In the red ink test, all 300 filled and sealed packages were liquid tight with no leak points.

Example 2

In two consecutive steps with a drying step in between, a water composition of water-soluble and dispersed PVOH was prepared in a manner similar to Example 1, the water composition having a saponification degree of more than 99% and 10% by weight of To exfoliate the bentonite, the aqueous composition was applied by liquid spraying onto a tissue paper with a total of 50 g/m ² and a PVOH coating of 3 g/m ² . The wet applied coating is dried with hot air to evaporate moisture.

In a subsequent step, the PVOH-coated paper was coated, ie an aluminum metal coating was applied to the PVOH layer by a vapor deposition method until an optical density of 3 was achieved.

Thus, the metallized, PVOH covered paper was laminated to a 50 g/ ^m2 tissue paper by extrusion lamination of a low density polyethylene (LDPE) thermoplastic tie layer. The inner side of the laminated interlayer paper was further coated by heat laminating a BOPP film with an EAA adhesive layer onto the inner side. The inner side of the BOPP film was coextrusion coated with two layers of LDPE. Wherein the innermost layer is a liquid-tight, heat-sealable LDPE extruded at a temperature of about 280°C.

Thereafter the coated and laminated laminated paper sandwich is covered on both sides with a thermoplastic heat-sealable layer (LDPE) and sealed under the trademark Tetra Brik with suitable induction heat sealing of the packaging container produced. The heat seal quality test is carried out on the conventional filling machine.

Alternatively, it is technically possible to metallize a thicker paper layer (eg about 100 g/m ² ) and not laminate it into any further paper layers but keep it as a single covering with an externally accessible Paper laminates with heat-sealed thermoplastic layers. However, it is currently not cost-effective to vapor-deposit metallised layers onto such thick paper substrates, which is why the above-mentioned sandwich laminates are manufactured in order to provide the corresponding required thickness and stiffness. of laminated materials.

The heat seal quality and the integrity of the packages produced were also very good according to the same evaluations made with the same test panel.

Comparative Example 1

An aluminum metal coating was applied to a 12 μm oriented PET (polyethylene terephthalate) substrate film by vapor deposition to an optical density of approximately 3.

The metallized, PET film is laminated to a cardboard of about 260 mN (or about 270 g/m ² ) by extrusion lamination of a thermoplastic tie layer of low-density polyethylene (LDPE), and is subsequently coated with thermoplastic on both sides. Heat-sealable layer (LDPE) covered and produced with suitable induction heat sealing of the packaging container under the trademark Tetra Brik The heat seal quality test is carried out on the conventional filling machine.

Compared to the above example, the heat seal quality and integrity of the produced package was acceptable as assessed by the test panel for the tear performance of the seal and the package integrity using the red ink test. However, for laminates with thin paper substrates, the sealing results of the tests were not consistent and reliable from test to test.

Comparative example 2

A thin paper web with a surface weight of 50 g/m ² was coextruded with a first layer of LDPE of 10 g/m ² and a second layer of EAA (ethylene acrylic acid copolymer) of 5 g/m ² Press to cover.

In a subsequent step, the extrusion-coated paper was further covered with an aluminum metal coating onto the EAA layer by a vapor deposition method.

The metallised, LDPE/EAA covered paper is laminated on both sides with a thermoplastic heat-sealable layer and is sealed with suitable induction heat sealing of the produced packaging container under the analog trademark Tetra Brik Heat-sealing quality testing is performed on a test bench under real conditions on a conventional filling machine. Moreover, suitable induction heat sealing of the produced packaging containers is carried out under the trademark Tetra Brik The laminated paper was tested on a conventional filling machine.

Comparative performance and quality of samples of sealed packaging materials and containers are based on data from Tetra Years of experience in quality control of traditional packaging laminates for Aseptic packaging containers was evaluated and it became clear that packages without proper seals could be formed on the TBA filling machine, which is why any further package integrity testing was not required . Furthermore, the results of the tear evaluation of the sealed samples on the bench showed that the seal was not good enough.

Therefore, the heat seal quality and integrity of the produced package was not good and not at all comparable to that of today's Tetra Brik aseptic, foil-based packages, as assessed by the same test panel. the same level.

Example 3

Example 3 was prepared in a manner similar to Example 1 except that no exfoliated layered smectite particles were present.

The heat seal quality and integrity of the packages produced were, as assessed by the test team, very good and comparable to the seal quality of today's Tetra Brik Aseptic, aluminum foil based packages. In the red ink test, all 300 filled and sealed packages were liquid tight with no leak points.

Example 4

As listed in Table 1, tissue papers of different surface weights were dissolved and dispersed in water with a degree of saponification above 99% and 10% by weight of exfoliated bentonite in two consecutive steps with a drying step in between. The aqueous composition is applied by liquid coating. The wet applied coating is dried with hot air to evaporate moisture.

In a subsequent step, the PVOH-coated roll paper is covered, that is, the aluminum metal layer is covered on the PVOH layer by a vapor deposition method.

The metallized PVOH covered paper was coated on the inside by extrusion lamination of a BOPET film to the inside of the laminated interlayer paper using LDPE as tie layer. An innermost liquid-tight heat-sealable LDPE layer is applied to the inside of the BOPP film by extrusion coating. The laminate obtained is then coated on the outside with a thermoplastic liquid-tight heat-sealable layer and sealed with a suitable induction heat-sealing of the produced packaging container under the analog trademark Tetra Brik Heat seal quality testing is performed on a test bench under real conditions in a conventional filling machine.

From the results it can be seen that thicker paper up to a certain surface weight has a better sealing effect than thinner paper. It can also be seen that higher optical density (OD) metal vapor deposited coatings have somewhat better sealing effects than lower OD metal vapor deposited coatings. Furthermore, it can also be seen that thicker PVOH layers somehow provide a better sealing effect than thinner layers. Similar to that shown in Example 1, all of the samples in Table 1 provided very good seal quality in the bench test and equally good package integrity results in the filling machine test. Although a thicker paper substrate of 70g/ ^m2 has a better sealing effect, a thinner substrate of 50g/ ^m2 is generally used in tests because thicker substrates are more expensive.

Table 1

Sample serial number Paper g/m2 PVOH g/m2 Optical density 1 50 2×0,7 3 2 50 2×1,5 1,5 3 50 2×1,5 3 4 70 2×1,5 3 5 70 2×0,7 1,5 6 70 2×0,7 3

It is of course also possible to further increase some gas barrier properties by covering thicker or further layers of PVOH composition, or by filling the PVOH layer with a higher content of inorganic particles. For example, improved odor barrier properties can be obtained by covering thicker and more densely packed gas barrier layer compositions. An excellent example of such a barrier composition comprises PVOH and talc particles in an amount of 10% to 50%, preferably 20% to 40%, by weight. Another example of such a barrier composition comprises PVOH and 10-50% by weight of talc particles and 1-40% by weight of nanoparticles, such as those mentioned above, eg clay.

Claims (35)

CLAIMS 1. A foil-free packaging laminate for induction heat sealing into packages for liquid food or beverages, the packaging laminate comprising at least one first layer (11) of paper or other cellulose-based material, the first A layer of paper or other cellulose-based material (11) is located on the inside of the packaging laminate and is pre-coated to receive and support the induction heat-sensitive metal vapor deposition layer (12) to induce heat sealing of the thermoplastic polymer material , the packaging laminate further comprises a metal vapor deposition layer (12) applied by vapor deposition to the inside of said pre-coated first paper or other cellulose-based material layer (11), and also comprises a coating layer an alignment film (20) pressed to said metal vapor deposited layer (12); and further comprising an innermost layer of liquid-tight, heat-sealable thermoplastic polymer material applied to the inner side of said alignment film (20) (14); or the oriented film comprises a liquid-tight heat-seal layer representing the innermost layer of the film, wherein the oriented film (20) has a tensile force of 2 or higher in at least one direction The elongation is stretched and there is a core layer of material having a higher melting point than the material of the innermost layer. 2. The foil-free packaging laminate according to claim 1, wherein said oriented film (20) is laminated to said metal vapor deposited layer (12) or said oriented film (20) via an intermediate adhesive layer An adhesive layer is included on its outer side to be laminated to the metal vapor deposited layer (12). 3. The non-foil packaging laminate according to claim 2, wherein the adhesive layer comprises a compound selected from the group consisting of ethylene acrylic acid copolymer (EAA), ethylene methacrylic acid copolymer (EMAA), ethylene-glycidyl ( Adhesive polymer of meth)acrylate copolymer (EG(M)A) and maleic anhydride-grafted polyethylene (MAH-g-PE). 4. The non-foil packaging laminate according to claim 2, wherein the tie layer is selected from copolymers of LDPE or LLDPE polymers, vinyl polymers having monomer units containing carboxyl or glycidyl functional groups and selected from ionomers based on low-density polyethylene. 5. The non-foil packaging laminate according to any one of the preceding claims, wherein at least the core layer of the oriented film is selected from the group consisting of polypropylene, polyethylene terephthalate, polyamide, polyamide Single oriented polymer film layer and biaxially oriented polymer film formed from ethylene naphthalate, polybutylene terephthalate, polytrimethylene terephthalate or mixtures of said polymers Groups of layers. 6. The foil-free packaging laminate according to any one of claims 1-4, wherein at least the core layer of the oriented film is biaxially oriented polypropylene or biaxially oriented polyethylene terephthalate alcohol esters. 7. The foil-free packaging laminate according to any one of claims 1-4, wherein the thickness of the oriented film is less than 30 μm. 8. The non-foil packaging laminate according to any one of claims 1-4, characterized in that the first layer of paper or other cellulose-based material (11) The innermost layer of the foil packaging laminate is covered with a higher melting point induction heat seal durable coating (13), and the induction heat sensitive metal vapor deposition coating (12) is further applied to the induction heat seal Durable coated inside. 9. The non-foil packaging laminate according to claim 8, characterized in that said induction heat seal durable coating (13) is applied by liquid application of a liquid composition to said first paper or other cellulose based material The layer (11) is formed by means of subsequent drying, said liquid composition comprising a polymeric binder dispersed or dissolved in a water-based or other solvent-based liquid medium. 10. The non-foil packaging laminate according to claim 8, characterized in that the induction heat-seal durable coating (13) is formed from a composition mainly comprising a polymer selected from the group consisting of polyvinyl alcohol ( PVOH), water dispersible ethylene vinyl alcohol copolymer (EVOH), ethylene vinyl alcohol vinyl acetate copolymer, polyvinylidene chloride (PVDC), water dispersible polyamide (PA), polysaccharide, polysaccharide derivative Substances, starch, starch derivatives and combinations of two or more of these substances. 11. The non-foil packaging laminate according to claim 8, characterized in that said induction heat-seal durable coating (13) is formed from a composition consisting essentially of a polymer selected from the group consisting of PVOH, water dispersed The group consisting of sexual EVOH or starch. 12. The non-foil packaging laminate of claim 9, wherein the liquid composition further comprises inorganic particulates. 13. Foil-free packaging laminate according to claim 8, characterized in that the induction heat-seal durable coating (13) is applied in a total amount of from 0.5 to 7 ^g /m2 in dry weight. 14. Foil-free packaging laminate according to claim 8, characterized in that the induction heat-seal durable coating (13) is applied in a total amount of from 0.5 to ⁵ g/m2 in dry weight. 15. Foil-free packaging laminate according to claim 8, characterized in that the induction heat-seal durable coating (13) is applied in a total amount of from 0.5 to ³ g/m2 in dry weight. 16. Foil-free packaging laminate according to claim 8, characterized in that the induction thermosensitive metal vapor deposition coating (12) is a layer made of aluminium. 17. Foil-free packaging laminate according to any one of claims 1-4, characterized in that the metal vapor deposited coating (12) has an optical density (OD) of from 1 to 3.5. 18. Foil-free packaging laminate according to any one of claims 1-4, characterized in that the metal vapor deposited coating (12) has an optical density (OD) of from 2 to 3. 19. The non-foil packaging laminate according to any one of claims 1-4, characterized in that the first layer (11) of paper or other cellulose-based material has a thickness of from 20 to 100 g/ ^m2 . The surface weight between. 20. The non-foil packaging laminate according to any one of claims 1-4, characterized in that the first layer (11) of paper or other cellulose-based material has a thickness of from 20 to 70 g/m ² . The surface weight between. 21. The non-foil packaging laminate according to any one of claims 1-4, characterized in that the first layer (11) of paper or other cellulose-based material has a thickness of from 30 to 60 g/m ² . The surface weight between. 22. The foilless packaging laminate of any one of claims 1-4, further comprising an outer side laminated to said first layer of paper or other cellulose-based material. A second paper or paperboard ply having a surface weight of from 50 to 500 g/m ² . 23. The non-foil packaging laminate of any one of claims 1-4, further comprising an outer side laminated to said first layer of paper or other cellulose-based material. A second paper or paperboard ply having a surface weight of from 200 to 400 g/m ² . 24. A method of manufacturing a non-foil packaging laminate according to any one of claims 1-23, comprising the steps of: - providing a first layer (11) of paper or other cellulose based material, - Pre-coating the first paper or other cellulose based material layer by applying an induction heat seal durable coating onto the inside of the first paper or other cellulose based material layer for receiving and supporting induction heat Sensitive metal vapor deposition coatings, - applying said induction thermosensitive metal vapor deposition coating (12) on the inner side of said first layer of paper or other cellulose based material to be coated, - providing an oriented film stretched in at least one direction with a stretch ratio of 2 or more and having a core layer of material having a higher melting point than the material of the innermost layer of said foil-free packaging laminate (20), - lamination of said oriented film (20) to said first layer of paper or other cellulose based material (11) coated with an induction thermosensitive metal vapor deposition coating (12), - providing one or more layers of liquid-tight, heat-sealable thermoplastic polymer material applied to the inner side of said oriented film (20), or as part of said oriented film (20) representing said film wherein said liquid-tight, heat-sealable thermoplastic polymer material or said liquid-tight heat-seal layer of said film represents the innermost layer of said foil-free packaging laminate layer. 25. The method of manufacturing a foil-free packaging laminate (10) according to claim 24, wherein the oriented film (20) is laminated to the induction thermosensitive metal vapor deposition coating (12) via an intermediate adhesive layer or the alignment film (20) includes an adhesive layer on its outer side, the adhesive layer being laminated to the metal vapor deposition coating (12). 26. The method of manufacturing a foil-free packaging laminate (10) according to claim 25, in The liquid-tight, heat-sealable thermoplastic polymer material is selected from LDPE, LLDPE, mLLDPE and VLDPE and mixtures thereof; The adhesive layer is selected from the group consisting of ethylene acrylic acid copolymer (EAA), ethylene methacrylic acid copolymer (EMAA), ethylene-glycidyl (meth)acrylate copolymer (EG(M)A) and maleic acid anhydride-grafted polyethylene (MAH-g-PE); and The tie layer is selected from LDPE or LLDPE polymers, copolymers of vinyl polymers having monomer units containing carboxyl or glycidyl functional groups, and from ionomers based on low density polyethylene. 27. The method of manufacturing a foil-free packaging laminate (10) according to any one of claims 24-26, wherein at least said core layer of said oriented film is selected from the group consisting of polypropylene, polyethylene terephthalate Mono-oriented polymer film formed from glycol ester, polyamide, polyethylene naphthalate, polybutylene terephthalate, polytrimethylene terephthalate or mixtures of said polymers layer and a group of biaxially oriented polymer film layers. 28. The method of manufacturing a foil-free packaging laminate (10) according to any one of claims 24-26, wherein at least the core layer of the oriented film is biaxially oriented polypropylene or biaxially oriented polypropylene. Ethylene terephthalate. 29. The method of manufacturing a foil-free packaging laminate (10) according to any one of claims 25-26, wherein the thickness of the oriented film is less than 30 μm. 30. The method of manufacturing a foil-free packaging laminate (10) according to any one of claims 24-26, wherein said pre-coating comprises the steps of: - providing a liquid composition comprising a polymeric binder dispersed or dissolved in a water-based or other solvent-based liquid medium, - formation of adjacent polymeric binder comprising said polymeric binder by applying (22a) the liquid composition to the inside of said first layer of paper or other cellulose-based material and subsequently drying (22b) to evaporate the liquid A thin induction heat-sealable durable coating on the inside of said first layer of paper or other cellulose-based material, said polymeric binder having a higher melting point than said innermost layer. 31. The method according to claim 30, wherein said induction heat seal durable polymer comprised in said liquid composition is selected from the group consisting of polyvinyl alcohol (PVOH), water dispersible ethylene vinyl alcohol copolymer (EVOH), Ethylene vinyl alcohol vinyl acetate copolymer, polyvinylidene chloride (PVDC), water-dispersible polyamide (PA), starch, starch derivatives and combinations of two or more of these . 32. The method according to any one of claims 24-26, wherein the induction heat seal durable coating (13) is applied in a total amount of from 0.5 to 7 g/m2 ^on a dry weight basis. 33. A method according to any one of claims 24-26, wherein the outer side of the first layer of paper or other cellulose-based material is also covered with a coating. 34. Packaging container (50a; 50b) made of the non-foil packaging laminate according to any one of claims 1-23. 35. A method of heat sealing a foilless packaging laminate comprising the steps of: - providing a non-foil packaging laminate as defined in any one of claims 1-23 in the form of a continuous web, - forming said foil-free packaging laminate in roll form into a continuous tube and sealing longitudinally in the longitudinal direction, - filling the tube formed by said non-foil packaging laminate with liquid food, - forming heat-sealed areas by induction heating at predetermined intervals in the transverse direction of the filled tube of said foil-free packaging laminate, and - Severing along the center line of each transverse sealing area to form individual containers.