Technical field

The present invention relates to a sheet- or web-shaped packaging laminate comprising magnetisable particles, in which the magnetisable particles are localised within one or more strip-shaped areas of the packaging laminate.

The present invention further relates to a packaging container produced from the packaging laminate, as well as a method of providing a packaging laminate comprising magnetisable particles with a possibility for magnetic marking.

The expression packaging laminate, as this is employed in connection with the present invention, is taken to signify both fibre-based packaging laminates and packaging laminates based exclusively on plastic. In its broadest scope, the expression encompasses packaging laminates including layers of optional combinations of plastic, fibre and inorganic material, for example metal, preferably aluminium foil.

Background art

It is previously known in the art to provide packaging laminates with integrated layers which offer a possibility for magnetic marking. Such layers include magnetisable particles and afford a possibility of being able to read-off, for example, a guide marking which is not located in any of the two outermost layers of the packaging material. The intention with such layers is to realise an alternative solution to optical or punched guide markings. Such guide markings are often printed in a colour tone in clear contrast to their surroundings, preferably black against a white background. Optical guide markings are normally placed in such panels of a continuous material web where no other printed markings or patterns are to be found or may be found. Guide markings of this type are employed in order, in connection

with multicolour printing, to adapt the position of the patterns printed with different colours to one another, so that the different colour patterns will lie in register above one another. Similarly, markings of the type under consideration here are employed for register maintenance, i.e. for controlling the position of a packaging material web in, for example, the tube forming- and filling unit of a filling machine so that the correct operation is carried out in the correct position, not least with respect to the printed decorative artwork of the packaging material. However, optical guide markings take up a certain area of the outside of the package, which, as a result, cannot be provided with decorative printing or information intended for an end user and may, moreover, be perceived as intrusive.

Gradually as the development of laminated packaging materials becomes increasingly sophisticated, it has become interesting, not least from the cost- and environmental viewpoints, to produce as thin packaging laminates as possible. If the intention is to provide a packaging laminate with a layer containing magnetisable particles, the paperboard layer which is included in the packaging laminate must display certain properties. In order to avoid the risk that those particles (which normally have a brown or black colour tone) which are to be found in the layer with magnetisable material inside the paperboard layer appear as a defacement of the outside of the packaging laminate, the paperboard layer must be sufficiently thick and/or possess such opacity that the applied particles are not seen through this layer. If such is not the case, the particles run the risk of imparting to the package an unattractive appearance. This is obviously not desirable and has resulted in packaging laminates comprising layers with magnetisable particles not having been commercially successful. The choice of magnetisable particles is large and must be made taking as the point of departure the intended use. However, it should be observed that the magnetisable particles may be both ferro- and ferrimagnetic. One preferred example of a magnetisable material is magnetite which is both commercially available and economical. Moreover, magnetite has very good magnetic properties.

Objects of the invention

One object of the present invention is thus to realise a packaging laminate of the type described by way of introduction through which the problems and drawbacks associated with the prior art technology can simply but effectively be obviated.

A further object of the present invention is to realise a method of producing a packaging laminate of the type described by way of introduction with a view to imparting to the packaging laminate a possibility for magnetic marking.

Yet a further object of the present invention is to realise a packaging container produced from the packaging laminate according to the present invention.

These and other objects and advantages will be attained according to the present invention by means of the characterising features as disclosed in appended Claims 1 and 5, respectively.

Expedient embodiments of the present invention have further been given the characterising features as set forth in the appended subclaims.

Description of the invention

According to the present invention, there will thus be realised a packaging laminate including magnetisable particles which are located within one or more strip-shaped areas of the packaging laminate. The packaging laminate is characterised in that the magnetisable particles are incorporated in a printing ink which has been applied within said one or more strip-shaped areas of the packaging laminate.

In that the packaging laminate according to the present invention, already in the conversion process, may be provided with such particle-containing strip-shaped area of printing ink, a both simpler and more effective handling of the packaging laminate

is made possible in, for example, a filling machine where the packaging laminate is intended to be reformed into packaging containers.

As was intimated above, the packaging laminate according to the invention is preferably provided with the particle-containing strip-shaped printing ink areas already during the production of the packaging laminate, whereby a magnetic marking of the packaging laminate is made possible which can be utilised as a guide marking in the production- or conversion process of the packaging laminate.

According to the invention, there will further be realised a packaging container produced from the packaging laminate which is provided with the possibility for magnetic marking which neither disfigures nor even takes up parts of the outside of the packaging container.

The possibility for magnetic marking in the present invention may thus advantageously be utilised in one or more optional stages in a value-added chain ranging from a material conversion process to any optional consumer stage.

In the method according to the present invention, the packaging laminate is provided with particulate magnetisable material within one or more optional strip-shaped areas of the packaging laminate. Preferably, the particulate magnetisable printing ink material is applied within such areas of the packaging laminate as, during the reforming of the packaging laminate into packaging containers, are intended to form so-called overlap joints or seams on the packaging container, since it is particularly easy to conceal the magnetic material between such overlapping parts of the packaging laminate.

One surprising advantageous property in the packaging laminate according to the invention is that the strip-shaped particle-containing area of printing ink can be made extremely narrow, with a width of only one or a few millimetres, and nevertheless make possible a functional magnetic marking such an information carrier. This is a consequence of the fact that the information carrying magnetic field which is

occasioned by the magnetisable particles has a detectable extent in all directions which is larger than the physical width of the strip-shaped area. In other words, the magnetic field describes a spatially geometric pattern which can be read-off by a suitable reader head or be detected by a suitable sensor without the reader head or the sensor needing to be or risking coming into physical contact with the thus magnetically marked packaging laminate.

Hence, the present invention makes possible practical applications within, for example, communication between packaging material and conversion/packing processes or for traceability purposes. One example of communication between material (packaging laminate) and packing process is register maintenance in a so- called form-fill-seal process where transverse seals of a tube-shaped material web must be put into effect in register with the printed decorative artwork. Another example is corresponding register maintenance where the packaging laminate is reformed into a tube by longitudinal sealing of the overlapping longitudinal edges of the packaging laminate (so-called overlap joints).

Those patterns which a detector device can give are vastly superior to today's methods of approach. As a result of the relation of the strip width to the reading width, the strip-shaped particle-containing printing ink area and its possible information will be at least as easy to detect as today's optically detectable markings. The strip-shaped magnetisable printing ink area according to the present invention will probably, therefore, in many contexts be able to supersede earlier marking principles, in particular those of the optically detectable type. The packaging laminate on which such a particle-containing strip-shaped area of printing ink is applied may advantageously be used in applications where it is intended to form either a tube or individual blanks, so-called cartons, for filling purposes. A feature common to these applications is that they include a longitudinal seal.

A particle-containing strip-shaped area of printing ink in a packaging laminate according to the present invention includes magnetisable particles in a quantity which may vary within extremely broad limits. In practice however, use is made, for

the objects of the present invention, of a quantity within the range of from 0.1 g/m ² up to 25 g/m ² . One preferred range is from 0.5 to 15 g/m ² , more preferably 1.0 to 8.0 g/m ² . In practical trials which have been conducted, it has proved to be possible, with suitable detecting- or read-off means, to detect and read-off, respectively, magnetic information from a distance of up to 4 mm from the information-carrying strip- shaped area of printing ink. As a consequence of the fact that the magnetic fields which the particle-containing strip-shaped area of printing ink gives rise to become relatively wide in relation to their physical extent, the positioning of a reader head need only be relatively exact.

A packaging container according to the present invention has preferably the particle- containing strip-shaped area of printing ink applied in an edge area. In particular, the packaging container may have the particle-containing strip-shaped area of printing ink applied in a so-called overlap joint or seam, for example a longitudinal seal area. In this case, the strip-shaped area of printing ink may be concealed practically entirely and thereby be rendered invisible on the packaging container. One particular advantage is that the application of such a strip-shaped particle-containing area of printing ink may be combined with the application of an edge sealing strip which is often employed in packaging containers of a paper- or paperboard-based packaging laminate in order to protect exposed fibre edges against edge-wicking.

Brief description of the accompanying Drawings

The present invention will now be described in greater detail hereinbelow, with reference to one embodiment shown on the accompanying Drawings, m the accompanying Drawings:

Fig. 1 is a schematic perspective view showing a packaging laminate web provided with strip-shaped particle-containing areas;

Fig. 2 is a partial section taken along the line II-II in Fig. 1 ;

Fig. 3 shows the upper part of a commercial packaging container provided with strip- shaped areas of a particle-containing printing ink according to the invention; and

Fig. 4 schematically shows one step in a laminate conversion process in which a strip-shaped area of a packaging laminate is coated with printing ink containing magnetisable particles in the method according to the present invention.

Detailed description of the invention

Fig. 1 illustrates the principle of how one or more strip-shaped areas 1 of printing ink containing magnetisable particles can be applied on a web 2 of the packaging laminate according to the invention. The web 2 is displaced in the direction of the double-headed arrow MD in a conversion line or in a filling machine and is provided, along its longitudinal edges 3, with a plurality of regularly strip-shaped areas Ia of the printing ink containing particles of a magnetisable material of optional length and width and/or with an endless strip-shaped area Ib of the printing ink.

As is apparent from Fig. 1, said strip-shaped areas Ia and Ib of printing ink are placed preferably close to and along the one or both longitudinal edges of the web 2 in order more readily to be able to be protected/concealed in a so-called overlap joint, as has previously been mentioned. Such an overlap joint is to be found on most packaging containers which are produced from sheets or from a web of a packaging laminate. The positioning of the particle-containing strip-shaped areas of printing ink close to the longitudinal web edges is particularly advantageous when the packaging laminate includes comparatively thin paper- or paperboard layers which are not sufficiently thick to render the packaging laminate totally opaque or non-transparent.

It is naturally possible to apply the strip-shaped particle-containing areas of printing ink 1 at any desired position on a web 2 of the packaging laminate. Further, the strip- shaped area or areas of printing ink can be applied already in connection with a conversion process or in a later stage, for example in connection with or immediately

before both of the longitudinal edges of the web are united to one another in an overlap joint.

Fig. 2 is a schematic cross section which shows one preferred example of a packaging laminate according to the present invention provided with a particle- containing strip-shaped area 1 of magnetisable printing ink.

The packaging laminate has a rigid, but foldable core layer 4 of paper or paperboard, as well as outer, liquid-tight coatings 6 of plastic, for example polyethylene, on both sides of the core layer 4.

It is clearly apparent from Fig. 2 how the particle-containing strip-shaped printing ink area 1 can be placed close to and along the one longitudinal edge of the packaging laminate.

Fig. 3 shows the upper region of a packaging container 12. The illustrated packaging container 12 may be produced from a web of the packaging laminate according to the invention by means of a filling machine which produces finished packaging containers in accordance with the known form-fill-seal principle. From the web, a tube is first formed in that both longitudinal edges of the web are united in an overlap joint in which both outer plastic coatings of the packaging laminate are sealed to one another in liquid-tight fashion by surface fusion. The tube is filled with the pertinent product, for example a liquid food product, and is divided into continuous, filled packaging units by repeated transverse seals of the tube transversely of the longitudinal direction of the tube beneath the product level of the tube. The packaging units are separated from one another by incisions in the transverse sealing zones and are given the desired geometric outer configuration, for example parallelepipedic, by an additional fold forming- and sealing operation.

It is apparent from Fig. 3 how the strip-shaped areas 13 of printing ink containing magnetisable particles may be placed on a finished packaging container. As a result of the illustrated positioning of these magnetisable areas of printing ink within the

area of the longitudinal overlap joint on the packaging container, these areas may effectively be concealed and made invisible to the eye. Moreover, this positioning of the particle-containing strip-shaped areas in an overlap joint contributes in the magnetisable particles' not running the risk of coming into contact with and being affected by either the packed product in the packaging container or by the surroundings of the packaging container.

Fig. 4 schematically shows how a packaging laminate may be provided with a particle-containing strip-shaped band in the manner according to the invention. From a magazine reel 7 a web of paper or paperboard is unwound in the direction of the arrow. The web is led along a conversion distance 8 where the web, along at least its one longitudinal edge is provided with or printed with a strip-shaped area of a printing ink containing magnetisable particles at a station 10 including one or more printing ink applicators. From the printing ink station 10, the web is led further along the distance 8 to an additional printing ink station 11 where the web, in a conventional manner, is provided with the desired printing ink decorative artwork by means of suitable printing ink applicators or printing ink rollers. From the printing ink station 11, the thus printed web is rolled up on a magazine reel 9 for further handling.

With the guidance of the description above, it will be obvious to a person skilled in the art that both the packaging laminate and the packaging container produced from the packaging laminate may be modified without departing from the inventive concept as this is defined by the appended Claims.