WO1998046425A1

WO1998046425A1 - A method for the production of a packaging laminate, and of packaging containers produced from the packaging laminate

Info

Publication number: WO1998046425A1
Application number: PCT/IB1998/000604
Authority: WO
Inventors: Marco Van De Pavoordt
Original assignee: Tetra Laval Holdings & Finance S.A.
Priority date: 1997-04-15
Filing date: 1998-04-08
Publication date: 1998-10-22
Also published as: SE514701C2; SE9701387D0; SE9701387L; AU6743298A

Abstract

A method of producing a packaging laminate (10) for a printing ink decorated packaging container with a bright metallic finish is disclosed. A metal coated plastic film (14, 15) imparting the bright metallic finish is applied on one side of a paper or paperboard web (11), the metal coated plastic film (14, 15) imparting the bright metallic finish being applied with the metal coating (15) of the plastic film (14) turned to face towards the paper or paperboard web (11). From the sheet or web-shaped packaging laminate (10), such printing ink decorated packaging containers with a bright metallic finish are produced by fold formation in such a manner that the metal coated plastic film (14, 15) of the packaging laminate (10) imparting the bright metallic finish forms the outside of the fold-formed packaging container.

Description

A METHOD FOR THE PRODUCTION OF A PACKAGING LAMINATE, AND OF PACKAGING CONTAINERS PRODUCED FROM THE PACKAGING LAMINATE

TECHNICAL FIELD

The present invention relates to a method for producing a packaging laminate for a packaging container with a printing ink decorated bright metallic outer finish, in which a metal coated plastic film imparting the bright metallic finish is applied on one side of a paper or paperboard web, and is thereafter provided with the desired printing ink decor.

The present invention also relates to packaging containers which are produced by fold forming of the packaging laminate and which have the metal coated plastic film imparting the bright metallic finish of the packaging laminate facing outwards on the finished packaging containers.

BACKGROUND ART

The growing needs of the market for sophisticated packaging containers with particularly well-decorated and aesthetically pleasing appearance with a view increasing the consumer attraction powers of the packaging container at the same time raise the demands placed on the packaging industry to provide competitive packaging containers of this type.

One prior art packaging container which is already available on the market and which meets the market's requirements on consumer attraction has, in addition to a beautifully printing ink decorated outside, also a bright metallic finish which imparts to the packaging container unparalleled consumer attractive power in its class.

The packaging material in this prior art packaging container has a layer of paper or paperboard and a metal coated plastic film imparting the metallic finish which is applied on the one side of the paper or paperboard layer with the metal coating of the plastic film facing away from the paper or paperboard layer. The metal coated side of the plastic film is coated with an outer, printing ink decorated plastic film which is bonded to the subjacent, metal coated plastic film with its printing ink decorated side facing towards the metal coating of the metal coated plastic film. The above described prior art packaging laminate is produced by a method according to which a metal coated plastic film imparting the bright metallic finish is applied on one side of a creased, punched, perforated web of paper or paperboard, with the metal coated side of the plastic film turned to face away from the paper or paperboard λveb, the thus applied metal coated plastic film being permanently united to the paper or paperboard web by means of an inteη^'acent layer of polyethylene.

The prefabricated packaging material of paper or paperboard and metal coated plastic film imparting the bright metallic finish is rolled up to form a packaging material reel and is transported for final processing, including printing ink decor, in the proximity of the market on which the packaging material is to be used.

On site, the prefabricated packaging material is unreeled and united with a prefabricated, printing ink decorated plastic film which, by means of heat and pressure, is permanently united to the web, with the printing ink decorated sided of the plastic film facing towards the metal coating of the metal coated plastic film on the web. The other side of the web is provided in a conventional manner with one or more layers of plastic and/ or materials other than plastic, for example aluminium foil, in order (if necessary) to supplement the barrier properties of the packaging material, depending upon the type of product which is to be packed using the finished packaging material.

The above method for producing a packaging laminate for a packaging container with printing ink decorated, bright metallic finish, makes for a rational production and distribution of the packaging material, but nevertheless suffers from serious drawbacks. For example, the method lacks flexibility in the choice of printing method and is practically entirely limited to so-called flexographic printing which gives a less distinct printing ink pattern than other conventional printing methods such as, for example, offset, which produces a printing ink pattern with considerably better printing quality than the flexographic method.

The prefabricated, printing ink decorated plastic film moreover requires excessively meticulous regulation and control in order to be able to apply the plastic film in register with tear perforations, punched holes, crease lines etc., which are applied to the paper or paperboard web already in connection with the prior production of the prefabricated packaging material. OBJECTS OF THE INVENTION

One object of the present invention is therefore to obviate the above- described drawbacks.

A further object of the present invention is to realise a method for producing a packaging laminate for a packaging container with printing ink decorated bright metallic finish, the method permitting free choice of printing method, in particular offset printing, on decoration of the packaging laminate.

Yet a further object of the present invention is to realise a packaging container with printing ink decorated bright metallic finish.

SOLUTION

These and other objects and advantages will be attained according to the present invention by means of a method as claimed in independent Claim 1 and by means of the packaging container as claimed in independent Claim 10, respectively. Further expedient embodiments of the method according to the present invention have moreover been given the characterizing features as set forth in the appended subclaims.

BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS

The present invention will now be described and explained in greater detail hereinbelow, with particular reference to the accompanying Drawings, in which:

Fig. 1 is a schematic cross sectional view of a packaging laminate according to the invention; and

Figs. 2A and 2B schematically illustrate how the packaging laminate of Fig. 1 may be produced by the method according to the invention, Fig. 2A illustrating the production of a prefabricated packaging laminate and Fig. 2B illustrating the final processing of the prefabricated packaging laminate.

DESCRIPTION OF PREFERRED EMBODIMENT

Fig. 1 thus 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, i.e. a packaging container with printing ink decorated, bright metallic finish on the outside, which has been produced using the method according to the invention. The packaging laminate 10 has a carrier core layer 11 of paper or paperboard with immediately surrounding layers 12, 13 of thermosealable plastic on both sides of the core layer 11.

The packaging laminate 10 in Fig. 1 is oriented in a position in which all illustrated layers above the paper or paperboard layer 11 are intended to be turned to face outwards, while, correspondingly, all illustrated layers beneath the paper or paperboard 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 previously mentioned layers above the paper or paperboard layer 11 will form the outside of the finished packaging container, while the layers beneath the paper or paperboard layer 11 in Fig. 1 will consequently form the inside of the packaging container, at the same time as the paper or paperboard layer 11 constitutes a central layer in the walls, bottom and top of the packaging container. In order to make the body of this description clearer and thereby 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 paper or paperboard layer 11, in which event the layers above the paper or paperboard layer 11 and the layers beneath the paper or paperboard layer 11 in Fig. 1 thus being disposed in this sense on the outside and inside of the packaging laminate 10, respectively.

The thermosealable plastic layer 12 on the outside of the packaging laminate 10, and the thermosealable plastic layer 13 on the inside of the packaging laminate 10 preferably, but not necessarily, consist of mutually the same plastic which, in the illustrated example, is assumed to be polyethylene, preferably low density polyethylene (LDPE).

The packaging laminate 10 further has a metal coated plastic film 14, 15 imparting a bright metallic finish, the plastic film 14, 15 being permanently united with the paper or paperboard layer 11 by the intermediary of the interjacent thermosealable plastic layer 12, with the metal coating 15 of the metal coated plastic film 14, 15 imparting the bright metallic finish being turned to face towards the paper or paperboard layer 11 on the outside of the packaging laminate 10. Preferably, the metal coated plastic film 14, 15 imparting the bright metallic finish consists of a transparent plastic film 14 of polypropylene (PP), preferably oriented polypropylene (OPP) which, on its one side, has a very thin continuous metal coating 15, preferably an aluminium coating applied by conventional vacuum deposition methods, and giving the plastic film a beautiful bright silver appearance when the plastic film is viewed from the other direction, i.e. from its non-coated side. Since the applied metal coating 15 only serves the purpose of imparting to the plastic film 15 a beautiful bright metal finish, the metal coating 15 may be made very thin, as has already been pointed out, and to this end, coating thicknesses of between approx. and approx. have proved to be fully sufficient and optimal. Above the metal coated plastic film 14, 15 imparting the bright metallic finish, the packaging laminate 10 has the desired decor 16 of printing ink which, by means of conventional printing methods, is applied to the surface of a layer 17 of thermosealable plastic applied between the printing ink decor 16 and the plastic film 14. The printing ink decor 16 is finally covered or protected under an outer layer 18 of thermosealable plastic applied above the printing ink decor 16 and preferably consisting of polyethylene, e.g. low density polyethylene (LDPE).

In the preferred example of a packaging laminate 10 according to the invention in which the metal coated plastic film 14, 15 imparting the bright metallic finish has a plastic film 14 consisting of oriented polypropylene (OPP) and in which the thermosealable outer plastic layer 18 protecting the decor consists of polyethylene, preferably low density polyethylene (LDPE), the above-mentioned interjacent thermosealable plastic layer 17 preferably consists of a blend of polyethylene and polypropylene which, with good adhesion, bonds both to the outer thermosealable plastic layer 18 of polyethylene and to the subjacent metal coated plastic film 14 of polypropylene, preferably oriented polypropylene (OPP).

As was pointed out above, the printing ink decor 16 on the outside of the packaging laminate 10 may be applied using any suitable conventional printing method whatever, e.g. by means of the offset method, the flexograph method, the rotoprint-method etc., and one of the advantages afforded by the present invention, above and beyond the previously described prior art technique is that the printing ink decor 16 can advantageously be applied using the so-called offset method which produces a printing ink decor 16 of supremely better printing quality than, for example, the so-called flexographic method. The inside of the packaging laminate 10 is not a germane part of the present invention and consequently is not critical to the invention, whose major object is to provide a packaging container with a printing ink decorated bright metallic finish. The inside of the packaging laminate 10, i.e. the layers beneath the carrier core paper or paperboard layer 11 in Fig. 1, may therefore vary and is exclusively determined in view of the product which is to be packed in a packaging container produced from the packaging laminate 10.

For example, the inside of the packaging laminate 10 may consist entirely or exclusively of the thermosealable plastic layer 13, but if the packaging laminate 10 is to be used for, for example, oxygen gas sensitive products such as juice, the packaging laminate 10 must be provided with at least one oxygen gas impermeable layer on its inside in order to impart to the packaging lairiinate 10 the requisite oxygen gas barrier properties. In the illustrated example, the packaging laminate 10 has an aluminium foil 19 serving as oxygen gas barrier and disposed between the thermosealable plastic layer 10 and one or more additional thermosealable plastic layers 20, 21 on the inside of the packaging laminate 10, of which the thermosealable plastic layer 21 is provided as outermost product contact layer. Other examples of known oxygen gas barrier materials which may be employed as oxygen gas barrier in a packaging laminate according to the present invention are ethylene vinyl alcohol copolymer (ENOH), polyamide (PA), polyester (PET), etc.

Figs. 2A and 2B schematically illustrate the method for producing the packaging laminate 10 according to the present invention, and in order to facilitate reading of this description, the same reference numerals as in Fig. 1 have also been employed for the same or corresponding parts in Fig. 2A and Fig. 2B.

A web 11 of paper or paperboard is unreeled from a magazine reel (not shown), at the same time as a corresponding web 14, 15 of metal coated plastic film imparting the bright metallic finish is unreeled from another magazine reel (not shown). Both webs 11 and 14, 15 are united to one another, with the metal coating 15 of the metal coated plastic film 14, 15 imparting the bright metallic finish turned to face towards the paper or paperboard web 11, and are then led together through the nip (at 22) between two rotary hot rollers 23, 24, at the same time as a film 12 of thermosealable plastic is extruded between the two webs 11 and 14, 15 by means of an extruder 25 disposed in association with the roller nip 22. In order to increase the adhesive bond between the two webs 11; and 14, 15, respectively, ozone is preferably aspirated against the extruded plastic film 12 from both sides. During passage through the roller nip 22, the webs are lightly pressed against one another, whereby the webs are permanently united to one another for the formation of a prefabricated packaging laminate web 26.

The prefabricated packaging laminate web 26 is thereafter rolled up for storage prior to transport and final processing elsewhere, at a place close to the market on which the finished packaging laminate is to be employed.

Fig. 2B schematically illustrates this second stage of the method according to the invention for final processing of the prefabricated packaging laminate 26. A web 26 of prefabricated packaging laminate which has been produced by means of the method illustrated in Fig. 2A is unwound from a magazine reel (not shown) and is led through a printing station at 27 where the web 26 is provided with the desired printing ink decor 16 by means of conventional printing methods, preferably the offset method. After drying of the applied printing ink, the printing ink decorated side of the web 26 is coated with an outer layer 18 of thermosealable plastic, at the same time as the other side of the web is provided with one or more layers of plastic and / or other material in order to impart to the packaging laminate 10 the desired barrier properties and possibly other properties which suit the product for which the packaging laminate 10 is intended.

Finished packaging containers are thereafter produced from the finished packaging laminate 10 in a conventional manner employing a so- called form-fill-seal process according to which a sheet or web-shaped packaging laminate 10 preferably provided with creases is reformed by fold formation into finished packaging containers which are filled with the intended product and are thereafter sealed.

It will be apparent from the foregoing description that the present invention, by simple means, makes for a rational production of printing ink decorated packaging containers with a bright metallic finish which, as opposed to prior art bright metallic finish printing ink decorated packaging containers, may be provided with the desired printing ink decor using the quality-assured offset method.

The present invention should not be considered as restricted to that described above and shown on the Drawings, many modifications being conceivable without departing from the spirit and scope of the appended Claims.

Claims

WHAT IS CLAIMED IS:

1. A method for producing a packaging laminate for a packaging container with a printing ink decorated bright metallic outer finish, in which a metal coated plastic film (14, 15) imparting the bright metallic finish is applied on one side of a paper or paperboard web (11), and is thereafter provided with the desired printing ink decor (16), characterized in that the metal coated plastic film (14, 15) imparting the bright metallic finish is applied on the paper or paperboard web (11) with the metal coated side of the plastic film (14) facing towards the paper or paperboard web.

2. The method as claimed in Claim 1, characterized in that the metal coated plastic film (14, 15) imparting the bright metallic finish is united with the paper or paperboard web (11) by means of a layer (12) of sealing plastic which is extruded between the plastic film (14) and the paper or paperboard web (11).

3. The method as claimed in Claim 2, characterized in that the sealing plastic layer (12) is extruded at the same time as ozone is applied for purposes of promoting adhesive bonding on both sides of the extruded sealing plastic (12).

4. The method as claimed in Claim 2 or 3, characterized in that said sealing plastic consists of polyethylene.

5. The method as claimed in any of the preceding Claims, characterized in that the metal coated plastic film (14, 15) has, on its non-metal coated surface, an outer layer (17) of thermosealable plastic on which the desired printing ink decor (16) is applied by means of conventional printing methods.

6. The method as claimed in any of the preceding Claims, characterized in that the desired printing ink decor (16) is applied by means of the offset method.

The method as claimed in any of the preceding Claims, characterized in that the metal coated plastic film (14, 15) imparting the bright metallic finish is, after application of the desired printing ink decor (16), provided with an outer transparent layer (18) of thermosealable plastic.

8. The method as claimed in any of the preceding Claims, characterized in that the metal coated plastic film (14, 15) imparting the bright metallic finish includes a layer (14) of polypropylene.

9. The method as claimed in Claim 8, characterized in that the polypropylene layer (14) of the metal coated plastic film imparting the bright metallic finish consists of oriented polypropylene.

10. A packaging container with printing ink decorated outer bright metallic finish, characterized in that it is produced by fold formation of a sheet or web-shaped packaging laminate (10) according to any of the preceding Claims, the metal coated plastic film (14, 15) of the packaging laminate imparting the bright metallic finish forming the outside of the fold formed packaging container.