WO2018229146A1

WO2018229146A1 - A packaging laminate and a packaging container produced from the laminate

Info

Publication number: WO2018229146A1
Application number: PCT/EP2018/065694
Authority: WO
Inventors: Alain COLLAUD
Original assignee: Tetra Laval Holdings & Finance S.A.
Priority date: 2017-06-13
Filing date: 2018-06-13
Publication date: 2018-12-20
Also published as: CN208006409U

Abstract

A packaging laminate comprising a bulk layer, an outermost, transparent, thermoplastic heat sealable layer directed towards the outside of a package formed from the packaging laminate, and an innermost heat sealable thermoplastic layer directed towards the inside of a package to have direct contact with the filled product, is provided. A packaging container produced from the packaging laminate is also provided, and in particular intended for liquid food and beverage packaging.

Description

A PACKAGING LAMINATE AND A PACKAGING CONTAINER

PRODUCED FROM THE LAMINATE

Technical Field

The present invention relates to a packaging laminate and a packaging container produced from, the packaging laminate. In particular, the invention relates to a packaging laminate and packages for packaging of liquid food or beverage.

Background

Packaging containers of the single use disposable type for liquid foods are often produced from, a packaging laminate based on paperboard or carton. One such type of packaging container is principally employed for aseptic packaging of liquid foods such as milk, fruit juices etc, sold for long term ambient storage. The packaging material in this known, packaging container is typically a laminate comprising a bulk- layer of paper or paperboard and outer, liquid-tight layers of thermoplastics. In order to render the packaging container gas-tight, in particular oxygen gas-tight, for example for the purpose of aseptic packaging and packaging of milk or fruit juice, the laminate in these packaging containers normally comprises at least one additional, layer, most commonly an aluminium foil.

On the inside of the laminate, i.e. the side intended to face the filled food contents of a container produced from the laminate, there is an innermost layer, applied onto the aluminium foil, which innermost, inside layer may be composed of one or several part layers, comprising heat sealable thermoplastic polymers, such as adhesive polymers and/or polyolefins. Also, on the outside of the bulk layer, there is an outermost heat scalable polymer layer.

The packaging containers are generally produced by means of modern, highspeed packaging machines of the type that form, fill and seal, packages from a web or from prefabricated blanks of packaging material. Packaging containers may thus be produced by reforming a web of the laminated packaging material into a tube by uniting both of the longitudinal, edges of the web to each other in an overlap joint by welding together the inner- and outermost heat scalable thermoplastic polymer layers. The tube is filled with the intended liquid food product and is thereafter divided into individual packages by repeated transversal seals of the tube at a predetermined distance from each other below the level of the contents in the tube. The packages are separated from, the tube by incisions along the transversal seals and are given the desired geometric configuration, normally parallelepipedic or cuboid, by fold formation along prepared crease lines in the packaging material.

The main advantage of such a continuous tube-forming, filling and sealing packaging method concept is that the web may be steri.li.sed continuously just before tube-forming, thus providing for the possibility of an aseptic packaging method, i.e. a method wherein the liquid content to be filled as well as the packaging material itself are reduced from bacteria and the filled packaging container is produced under clean, conditions such that the filled package may be stored for a long time even, at ambient temperature, without the risk of growth, of micro-organisms in the filled product. Another important advantage of this type of packaging method is, as stated above, the possibility of continuous high-speed packaging, which has considerable impact on cost efficiency.

Typically, many thousands of packages may be prepared per hour. For example,

i high-speed packaging machines may manufacture about 15 000 packages per hour (family- size packaging containers of 0.9 litres and above), and about 24 000 packaging containers per hour (portion packages).

Packaging containers for sensitive liquid food, for example milk or juice, can also be produced from sheet-like blanks or prefabricated blanks of the laminated packaging material of the invention. From a tubular blank of the packaging laminate that is folded flat, packages are produced by first of all folding and sealing the blank to form an open tubular container capsule, of which one open end is closed off by means of folding and heat-sealing of integral end panels. The thus closed container capsule is filled with the food product in question, e.g. juice, through its open end, which is thereafter closed off by means of further folding and heat-sealing of corresponding integral end panels. An example of a packaging container produced from sheet-like and tubular blanks is the conventional so-called gable-top package. There are also packages of this type which have a moulded top and/or opening device made of plastic.

The growing needs of the market for sophisticated packaging containers with particularly well-decorated and aesthetically pleasing appearance with a view to increase the power of attracting consumers at the same time raise the demands placed on the packaging industry to provide competitive packaging containers of this type. Visual attractiveness and differentiation opportunities towards consumers is very important for packaging of every-day food, to compete with other brands of foods. An infinite variety of colourful visual effects is desirable. Therefore, there is a need for realizing a packaging laminate with such increased visual attractiveness.

Summary

To support the above ambition, the present invention provides a packaging laminate, i.e. a laminated packaging material, comprising a bulk layer, an outermost, transparent, thermoplastic heat sealable material layer directed towards the outside of a package formed from the packaging laminate, and an innermost heat sealable thermoplastic material layer directed towards the inside of a package to have direct contact with the filled product, wherein the packaging laminate further comprises a holographic film or sheet which is arranged on the outside of the bulk layer, i.e. between the bulk layer and the outermost, transparent, thermoplastic heat sealable material layer.

The bulk layer may be a paper or paperboard or other cellulose-based material.

According to another aspect, a packaging container is provided, produced from the packaging laminate of the present invention.

The packaging laminate described above and in the appended claims, provide that almost unlimited variations of attractive design- and appearance-features to the decor of packages for high-speed liquid food packaging may be added, while at least maintaining the required properties regarding package integrity, long term ambient, aseptic performance, as well as suitability for high-speed manufacturing and packaging of food at a reasonable cost. Brief Description of the Drawings

The present invention is illustrated by way of example, and not by way of limitation, in the accompanying drawings, in which like reference numerals refer to similar elements, and in which:

Fig. 1 shows an illustrative example of the packaging laminate 10 according to the present invention.

Fig 2 shows an illustrative example of the holographic film 12.

Fig 3 shows an illustrative example of the packaging laminate 10 according to the present invention.

Fig 4 shows an illustrative example of a cuboid-shape packaging container, made from the packaging material of the invention.

Fig. 5 shows a further illustrative example of a pouch-shaped packaging container.

Reference numerals used in the drawings are as follows:

11 bulk layer

11a clay coat (smoothening layer)

12 holographic film or sheet

12a holographic pattern

12b polymer base film (or paper base layer) for carrying the holographic pattern

13 printed decor, i.e. decorative colour print

14 thermoplastic heat sealable and transparent outermost material layer

15 lamination layer

16 barrier layer

17 innermost heat sealable, thermoplastic material layer

Detailed Description

With the term "long-term storage" in connection with the present invention, is meant that the packaging container should be able to preserve the qualities of the packed food product, i.e. nutritional value, hygienic safety and taste, at ambient conditions for at least 1 or 2 months, such as at least 3 months, preferably longer, such as 6 months, such as 12 months, or more.

With the term "package integrity", is generally meant the package tightness, i.e. the resistance to leakage or breakage of a packaging container. It encompasses the resistance of the package to intrusion of microbes, such as bacteria, dirt, and other substances, that may deteriorate the filled food product and shorten the expected shelf-life of the package.

One main contribution to the integrity of a package from a laminated packaging material is provided by good internal adhesion between adjacent layers of the laminated material. Another contribution comes from the material resistance to defects, such as pinholes, ruptures and the like within each material layer itself, and yet another contribution comes from the strength of the sealing joints, by which the material is sealed together at the formation of a packaging container. Regarding the laminated packaging material itself, the integrity property is thus mainly focused on the adhesion of the respective laminate layers to its adjacent layers, as well as the quality of the individual material layers. Regarding the sealing of the packages, the integrity is mainly focused on the quality of the sealing joints, which is ensured by well-functioning and robust sealing operations in the filling machines, which in turn is ensured by adequately adapted heat-sealing properties of the laminated packaging material.

The term "liquid or semi-liquid food" generally refers to food products having a flowing content that optionally may contain pieces of food. Dairy and milk, soy, rice, grains and seed drinks, juice, nectar, still drinks, energy drinks, sport drinks, coffee or tea drinks, coconut water, wine, soups, jalapenos, tomatoes, sauce (such as pasta sauce), beans and olive oil are some non-limiting example of food products contemplated.

The term "aseptic" in connection with a packaging material and packaging container refers to conditions where microorganisms are eliminated, in-activated or killed. Examples of microorganisms are bacteria and spores. Generally, an aseptic process is used when a product is aseptically packed in a packaging container. For the continued aseptic property during the shelf-life of the package, the package integrity properties are of course very important. For long-term shelf-life of a filled food product, it may furthermore be important that the package has barrier properties towards gases and vapours, such as towards oxygen gas, to keep its original taste and nutritional value, such as for example its vitamin C content.

With the term "bulk layer" is normally meant the thickest layer or the layer containing the most material in a multilayer laminate, i.e. the layer which is contributing most to the mechanical properties and the dimensional stability of the laminate and of packaging containers folded from the laminate, such as paper, paperboard, or carton, or other cellulose -based material. It may also mean a layer providing a greater thickness distance in a sandwich structure, which further interacts with stabilising facing layers, which have a higher Young's modulus, on each side of the bulk layer, to achieve sufficient mechanical properties and dimensional stability.

The term "heat-sealing" refers to the process of welding one surface of a thermoplastic material to another thermoplastic surface. A heat-sealable material should, under the appropriate conditions such as applying sufficient heating and pressure, be able to generate a seal when pressed against and in contact with another suitable thermoplastic material. Suitable heating can be achieved by induction heating or ultrasonic heating or other conventional contact or convection heating means, e.g. hot air or impulse heating. Upon heating, the mobility of the polymer chains increases at the material surfaces intended for sealing to each other, such that the polymer chains disentangle and move and re-entangle with polymer chains from the opposite sealing surface. Upon cooling there are created strong bonds of entangled polymer chains across the sealing interface, thus bonding the two material surfaces to each other. The heat sealing operation has to occur within parts of a second and the duration of the different phases, such as heating, partly melting, bonding and cooling, is counted in milliseconds, in packaging machines that produce thousands of packages per hour.

The barrier materials employed in laminated packaging materials that benefit from the present invention are those that are sensitive to cracking when stretched or strained or flexed, such as at creasing, folding and shaping the laminated materials into pouches or cuboid packaging containers from the laminated material. An example of such barrier materials are metal foils, such as aluminium foil, such as of a thickness from 5 to 9 μιη. However, also very thin coatings of barrier materials onto a thicker substrate, of a polymer film or a thin paper sheet substrate, may suffer from a similar vulnerability, due to their minute thickness, which may be counted in a couple of micrometers only, or less, or as in the case of vapour deposition coatings or vacuum coatings, in nanometers. Examples are metallised coatings applied by physical vapour deposition, or other inorganic coatings such as coatings of silicon oxides or aluminium oxides, or coatings from so called amorphous diamond-like carbon (DLC) coatings.

The present invention will now be described in detail with reference to a few embodiments thereof as illustrated in the accompanying drawings. In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present invention. It will be apparent, however, to one skilled in the art, that the present invention may be practiced without some or all of these specific details. In other instances, well known process steps and/or structures are not described in detail in order to not unnecessarily obscure the present invention.

Fig. 1 shows a schematic cross-sectional view of one example of a packaging laminate 10 for a packaging container of the type described by way of introduction.

The packaging laminate 10 has a bulk layer 11 of paper or paperboard or other cellulose-based material. The packaging laminate 10 in Fig. 1 is oriented in a position in which all illustrated layers above the bulk layer 11 are intended to be turned to face outwards, while, correspondingly, all illustrated layers beneath the bulk layer 11 are intended to be turned to face inwards in a packaging container according to the invention produced from the packaging laminate 10. In other words, the layers above the bulk layer 11 will form the outside of the finished packaging container, while the layers beneath the bulk layer 11 in Fig. 1 will consequently form the inside of the packaging container, at the same time as the bulk layer 11 constitutes a central layer in the walls, bottom and top of the packaging container. In order to facilitate an understanding of the present invention, the expressions "inside" and "outside" will hereafter be employed in the same manner also for the packaging laminate 10, taking as the point of departure the central bulk layer 11, in which event the layers above the bulk layer 11 and the layers beneath the bulk layer 11 in Fig. 1 thus being disposed in this sense on the outside and inside of the packaging laminate 10, respectively.

The packaging laminate 10 further comprises a holographic film 12 on the outside of the bulk layer 11. The side having the holographic pattern 12a may be on the outer side or inner side, i.e. facing towards the outside or the inside. In an aspect, the holographic pattern may be applied to a paper base layer on its outer side. Alternatively, in an aspect, the side having the holographic pattern 12a of the holographic film 12 preferably faces the bulk layer 11, as shown in Fig. 3. On the backside, i.e. the polymer base film side 12b, of the holographic film 12, there is a decor layer 13, for example a decorative colour print, such as a printed colour pattern, optionally including text, nouns, marketing brands, logos etc. The decor layer 13 can thus be printed on the backside of the holographic film, facing towards the outside. In one embodiment, the decor layer 13 is printed on a printable primer coating, applied to the backside of the holographic film, for best possible adhesion. On the outside of the decor layer 13, there is an outermost transparent, thermoplastic sealing layer 14. The transparent, thermoplastic sealing layer 14 is used to protect the laminated structure and the bulk layer 11 from moisture since the bulk layer 11 is made of paper fibre, i.e. cellulose fibres, which must not get wet. A high transparency of the outermost layer is advantageous for the printed decor, and particularly for the holographic pattern to be distinctly visible towards the outside of the package, without distortion by any opacity or haze of the polymer base film 12b as well as the outermost layer 14.

For a best possible quality of the holographic pattern, visible on the finished, filled and sealed package, and for good adhesion and laminate integrity, the bulk layer 11 needs to have sufficient smoothness to support the glossy and sensitive shiny holographic surface of the holographic film 12. For this purpose, as shown in Fig. 3, it is preferred that the bulk layer 11 has a smoothening coating layer 11a, such as a smoothening clay-coating layer, applied on the outer side, facing the holographic film 12. This is particularly preferred when the holographic pattern 12a is applied to a polymer base film 12b, and not to a paper base layer.

The holographic film 12 may be adhered to the bulk layer 11 by a method and adhesive forming a bonding layer 18 as shown in Figs. 1 and 3, such as expensive melt extrusion lamination with an intermediate layer of LDPE/polyolefin or modified adhesive polyolefin, but may alternatively and preferably be laminated by using an aqueous adhesive, which is applied to the film side and then adhered to the bulk layer by absorbing the moist from the adhesive into the cellulose. A suitable aqueous adhesive composition comprises an ethylene acrylic acid copolymer (EAA) or an ethylene methacrylic acid copolymer (EMAA).

The bulk layer 11 may be any material layer providing dimensional stability and direct or indirect stiffness to the laminate, such as preferably a paperboard or carton or other cellulose-based material, and may specifically be of a liquid paperboard quality (i.e. such as used for any food packages, liquid food packages, aseptic liquid food packages, retortable food packages, sterilized and continuously formed filled and sealed packages for high-speed machinery and high-speed manufacturing).

The holographic film 12 may have different patterns and colours - all more or less glossy and shimmering (a kind of metallic appearance), providing a visually deep, dynamically shiny effect.

The over-coating with the melt extruded outermost PE layer, or the lamination/gluing of the film to the bulk layer 11 does not destroy the holographic pattern, which must be visible to the outside of the packaging container. The holographic film 12 can thus be turned with the holographic pattern surface towards the printed decor layer 13. And, when the holographic pattern is applied to a paper base layer on its outer side, the holographic pattern may be turned outwards.

Also, glossy/matte effects may be created in the surface of the holographic pattern. Parts of the holographic film surface may have the holographic pattern, and parts not. Register holding is not needed regarding the holographic pattern, if the pattern is continuous and covering the whole packaging laminate surface.

The polymer material of the holographic film 12 may be suitable polymer materials for oriented films, the normal choices are oriented polypropylene, such as biaxially oriented PP (BOPP) or oriented polyethylene terephthalate, such as BOPET. The holographic pattern coatings may alternatively be applied to a thin paper carrier layer, preferably coated with a thin polymer layer suitable for the purpose.

Other ways could be to melt-extrusion overcoat the holographic film 12 with a heat sealable thermoplastic polymer layer, print the decor on the outside thereof and further overcoat the printed decor with a thin lacquer or other thin protective coating.

The structure on the inside of the bulk layer 11 may be any structure, with or without oxygen barrier layers. In the embodiment of Fig. 1, on the inside of the bulk layer 11, there is a barrier layer 16 which is laminated to the bulk layer 11 through a lamination layer 15. The barrier layer 16 may be an aluminium foil, polyamide and EVOH barrier layers, vapour deposited and metallised films, etc. The lamination layer 15 may be a thermoplastic material or polymer, such as a polyolefin, preferably low density polyethylene, LDPE, but could also be another polyolefin, such as polypropylene (suitable for retortable packages), or other thermoplastic polymers, such as carboxylic-group modified polyolefins, such as EAA or EMAA.

On the inside of the barrier layer 16, there is an innermost heat sealable layer 17. The innermost heat sealable layer 17 is used to protect the bulk layer 11 from moisture. The innermost heat sealable layer 17 is a thermoplastic polymer, more specifically, a polyolefin, such as a polyethylene selected from LDPEs, LLDPEs, mLLDPEs and blends of any thereof. Alternatively, the innermost heat sealable layer 17 may be a heat sealable polypropylene homo- or copolymer, e.g. suitable for retortable packages.

According to the need, the packaging laminate 10 can be used to produce a folded packaging container with any shape, such as a cuboid or semi-cuboid shape (see Fig. 4). The packaging laminate 10 may also be used for pouch-shaped packages or wedge-shaped packages (see Fig. 5), or for bottle-shaped packages (not shown) having a plastic top and opening attached to a folded main body from the packaging laminate.

By introducing a holographic film or sheet into a packaging laminate structure in the manner described above, and in the claims, a new visually attractive decorative effect is enabled for heat sealable, mass-produced packaging containers, without jeopardizing any of the critical requirements based on the packages and without deteriorating the visual appearance of a holographic pattern. More specifically, liquid carton packages, which are the most demanding type of single- use packaging for sensitive goods, may be provided such that they at least maintain the properties required, in terms of package integrity and aseptic performance, while acquiring also increased attractiveness to retailers and consumers.

It will be apparent to those skilled in the art the embodiments described above is only illustrative and cannot be deemed as a limitation to present invention, and that various modifications and variations can be made to the embodiments described herein without departing from the spirit and scope of the claimed subject matter. Thus, it is intended that the specification covers modifications and variations of the various embodiments described herein, provided such modification and variations come within the scope of the appended claims and their equivalents.

Claims

1. A packaging laminate, the packaging laminate comprising a bulk layer of paper or paperboard or other cellulose-based material, an outermost, transparent, thermoplastic heat sealable layer directed towards the outside of a package formed from the packaging laminate, and an innermost heat sealable thermoplastic layer directed towards the inside of a package to have direct contact with a filled product, characterized in that the packaging laminate further comprises a holographic film or sheet which is arranged on the outside of the bulk layer.

2. The packaging laminate of claim 1, wherein the packaging laminate further comprises a decor layer, which is printed on the holographic film or sheet.

3. The packaging laminate of claim 2, wherein the decor layer is covered by the outermost, transparent, thermoplastic heat sealable layer.

4. The packaging laminate of any one of claims 1 to 3, wherein on the inside of the bulk layer, there is a barrier layer which is laminated to the bulk layer through a lamination layer.

5. The packaging laminate of any one of the preceding claims, wherein the packaging laminate further comprises a heat sealable layer on the inside of the barrier layer.

6. The packaging laminate of any one of the preceding claims, wherein the bulk layer is paper or paperboard or other cellulose -based material.

7. The packaging laminate of any one of the preceding claims, wherein the bulk layer further includes a smoothening layer on its outside surface.

8. The packaging laminate of claim 7, wherein the smoothening layer is a clay- coating layer which is laminated or adhered to the holographic film or sheet.

9. A packaging container produced from the packaging laminate according to any one of claims 1-8.