Title of Invention

"A WINDABLE FILM FOR FOOD PACKAGING"

Abstract

The invention relates to a rollable film for the production of a packaging, especially for foodstuffs, having sealing regions provided at least in sub-regions of the film, the film having a multi-layered structure and the sealing regions of a side of the film having varied adhesion properties. The sealing regions are defined by first sealing regions which are sealable to one another, especially outside/outside sealable, and by second sealing regions, especially inside/outside sealable sealing regions, the first sealing regions being thicker and/or covering a greater surface area than the second sealing regions. (Fig .1)

Full Text

Rollable film for the production of a packaging Description The invention relates to a rollable film for the production of a packaging in accordance with the precharacterising clause of patent claim 1. Films used for the production of a packaging are usually available in the form of blanks which are either manufactured as such or are separable from a film web. The latter variant, namely the provision of a roll of film which is generally wound onto a reel, has numerous advantages over the first alternative, primarily resulting from the ability of a film web to be produced effectively and efficiently as well as the improved handling ability of such a film web for further processing at a later stage. In order to be able to produce a packaging from a film it is necessary for the film web first to be divided into predetermined film blank portions. Thereafter, sub-regions, especially the edges, of the blanks are brought into contact with one another and bonded in order thus to form a closed packaging. In order that the desired portions of the film can be joined together more easily there is frequently used a sealing technique which enables the desired portions of the film to be sealed in a troublefree and simple manner. Adhesive sealing, for example, is used for that purpose. A problem that has arisen, however, is that film webs that have been prepared for such sealing have a tendency to stick to one another in layers, i.e. to block, as soon as they are laid one on top of another or, preferably, are wound onto a reel. This risk of blocking is further increased by elevated temperature, and the blocking can be so severe that the film web wound onto the reel can no longer be unwound and thus becomes unusable. One of the main reasons for the occurrence of this problem is the necessity for the film blank produced from the film web to exhibit inside/outside sealability, which means in practice that an upper side of the film is sealed to an underside of the film. Such an arrangement of upper sides and undersides is inevitably provided by a rolled-up film, however, which in the prior art frequently results in premature and undesirable "sealing" on the reel. The aim of the invention is to provide a cost-effective film having improved handling ability by means of which the above-mentioned problems, especially during rolling-up and also under elevated temperatures, can be avoided or eliminated. This aim is achieved by a reliable film for the production of a packaging in accordance with patent claim 1. In particular, the aim is achieved by a Tollable film for the production of a packaging, especially for foodstuffs, having sealing regions provided at least in sub-regions of the film, the film having a multi-layered structure and/or being provided with colorants, especially varnishes, for example "textured" varnishes, and the sealing regions of a side of the film having varied adhesion properties. An important aspect of the invention is that the sealing regions on a side of the film are so matched to one another in respect of their adhesion properties that extensive sealing between an upper side of a film web and a lower side of a further film web located above is minimized or totally avoided. According to the invention, the sealing regions having varied adhesion properties are defined by first sealing regions which are sealable to one another, especially outside/outside sealable, and by second sealing regions, especially inside/outside sealable sealing regions. The first sealing regions, that is to say the outside/outside sealable sealing regions, are arranged substantially along the length of the film and cover a greater surface area than the second sealing regions and are non-blocking with respect to the inner side of the film. By virtue of their relatively large and linear arrangement in the machine direction, the winding pressure that builds up in those regions is greater than in the remaining regions of the film. The second sealing regions are located according to the invention in a region of the film in which they do not overlap with the first sealing regions. This is especially the case when the film, which is preferably in the form of a film web, is rolled up or wound onto a reel. In that case, the second sealing regions will not overlap with the first sealing regions also seen over the cross-section of the roll, so that the second sealing regions will not cause a build-up in thickness relative to the remaining surface of the film on the reel. According to the invention, the surface area covered by the second sealing regions relative to the total surface area of the film is less than 5 %, preferably less than 3.8 % and especially less than 2.5 %. In this way it is ensured that the second sealing regions applied to the film, which are inside/outside sealable and could result in the rolled-up film webs' becoming stuck together, are only very small, so that the risk of extensive blocking is minimized or eliminated. Furthermore, according to the invention the first sealing regions are thicker than the second sealing regions, which can be realized simply by applying different amounts of a sealing medium. Alternatively and/or in addition, the surface area covered by the first sealing regions can be significantly greater, that is to say by a factor of from 3 to 30 times, than that of the second sealing regions. By virtue of their greater thickness and/or the substantially greater surface area covered by the first sealing regions in comparison with the second sealing regions, as the film web is being rolled up there is a build-up in thickness in the region of the first sealing regions extending substantially linearly along the length of the film. It should be emphasized at this point that the first sealing regions can also be arranged in a curving shape or in the form of dots or spots along the length of the film web and can otherwise be arranged in accordance with the sealing surface required. The important feature that is to be observed according to the invention is that the first sealing regions come to lie one above another when the film web is being rolled up and form a main pattern that supports the film web in the transverse direction. Because the second sealing regions are thinner and/or cover a substantially smaller surface area than the first sealing regions, the difference in the thickness of » * the first sealing regions relative to the second sealing regions serves as it were as a spacer during the rolling-up of the film web, so that the upper side of a lower film web does not come into direct contact with the underside of an upper film web, or does so only with a significantly reduced contact pressure, and accordingly those two film layers cannot unintentionally become stuck together. It should be noted that even in the event of the upper side of a lower film web coming into contact with the underside of an upper film web, by virtue of the increased thickness of the main pattern there is no risk of the two layers becoming firmly stuck together because, as a result of their reduced thickness, the second sealing regions are not subjected to winding pressure in the roll and the second sealing regions are thus relieved of load. According to the invention, the second sealing regions extend substantially in the transverse direction, that is to say at a right angle or obliquely relative to the longitudinal extent of the film. The second sealing regions are of substantially linear form, which means merely the general alignment of the second sealing regions. In principle, these second sealing regions can also have a wavy, zig-zag or dotted shape and extend in some other way transversely to the longitudinal extent of the film. By virtue of the substantially linear form of the second sealing regions, when the film is being rolled up the second sealing regions come to rest on different locations over the radius and around the circumference as a result of the increasing diameter of the roll during the rolling, so that a build-up in thickness caused by the second sealing regions1 lying one above another and the associated winding pressure that would act on the second sealing regions does not occur according to the invention. In that respect, an important aspect of the invention is that the inside/outside sealable second sealing regions are separated from one another by the spacing between the film webs having the second sealing regions. This spacing is brought about by the greater thickness of the first sealing regions relative to that of the second sealing regions. Accordingly, the main roll-supporting pattern, which is formed by the first sealing regions in the rolled state, is provided with an outside/outside sealable material having no blocking effect, whereas the second sealing regions, which cover a maximum surface area of 5 %, are inside/outside sealable, but are arranged one above another, without pressure, irregularly over the circumference of the roll. The materials used according to the invention are predominantly oriented polypropylene and polyethylene films. The film according to the invention is advantageously in the form of a film that is printed on its outer surface, i.e. face-printed, only the front side of the film being printed. It should be mentioned at this point that the printing or coating process as well as its basic principles are also applicable to the inner side or an underside of a film. Furthermore, it should be noted that the film is preferably in the form of a laminate, it also being possible for some of the laminate layers to be printing layers or sealing layers. Further embodiments of the invention will be found in the subsidiary claims. The invention will be described below with reference to an exemplary embodiment which is explained in greater detail with reference to one Figure: Fig. 1 is a diagrammatic representation of a rollable film according to the invention in accordance with an embodiment. In the description which follows, parts that are the same or have the same effect have been given the same reference numerals. Fig. 1 shows a rollable film 10 which is shown with its longitudinal extent running from top to bottom in the drawing. The film is in the form of a symmetrical double film for simultaneous production of two packagings, which can be divided along its centre line to form two identical films which can then be cut to length. Along its length, the film 10 has first sealing regions 21 on each side of the centre line 30 and along its side edges 40. Linear second sealing regions 22 extend at a right angle to those first sealing regions 21. The first sealing regions 21 have a larger amount of sealable dispersion varnish applied and accordingly rise to a greater height out of the plane of the drawing than the second sealing regions 22, so that when the film 10 is wound onto a reel (not shown) a main pattern of first sealing regions 21 lying one above another is formed and the film 50 located between the first sealing regions is arranged slightly spaced apart from adjacent film web layers located underneath. This is likewise true of the second sealing regions 22. In summary, it should be mentioned that the spaced arrangement of the film regions between the first sealing regions in the rolled-up state prevents those regions 50 becoming stuck together. This is true especially in the case of elevated temperatures, which would render conventional film webs unusable. It should be pointed out here that all the above-described components, alone and in any combination, especially the details shown in the drawing, are claimed as being important to the invention. Modifications thereof will be familiar to the person skilled in the art. List of reference numerals 10 film 21 first sealing regions 22 second sealing regions 30 centre line 40 side edge 50 regions between first sealing regions Rollable film for the production of a packaging Patent claims 1. Rollable film (10) for the production of a packaging, especially for food stuffs, having sealing regions (21, 22) provided at least in sub-regions of the film, characterized in that the film (10) has a multi-layered structure and the sealing regions (21, 22) of a side of the film have varied adhesion properties. 2. Film according to claim 1, characterized in that the sealing regions (21, 22) having varied adhesion properties are defined by first sealing regions (21) which are sealable to one another, especially outside/outside sealable, and by second sealing regions (22), especially inside/outside sealable sealing regions. 3. Film according to claim 2, characterized in that the first sealing regions (21) are arranged substantially along the length of the film (10), especially the film web, and the second sealing regions (22) are arranged in a region of the film (10) that does not overlap with the first sealing regions (21), especially over the cross-section of the roll in the rolled state. 4. Film according to either one of claims 2 and 3, characterized in that the first sealing regions (21) have a dispersion varnish, especially an acrylate-based dispersion varnish. 5. Film according to either one of claims 2 and 3, characterized in that the second sealing regions (22) have a dispersion varnish, especially a dispersion varnish based on ethyl vinyl acetate. 6. Film according to any one of claims 2 to 5, characterized in that the first sealing regions (21) are thicker and/or cover a greater surface area than the second sealing regions (22). 7. Film according to any one of the preceding claims, characterized in that the first sealing regions (21), to avoid inside/outside sealing, are provided with colorant, varnish, especially a textured varnish, and/or anti-adhesion agents. 8. Film according to any one of claims 2 to 7, characterized in that the second sealing regions (22) cover a surface area of less than 5 %, preferably less than 3.8 % and especially less than 2.5 %, relative to the total surface area of the film (10). 9. Film according to any one of the preceding claims, characterized in that the first sealing regions (21) are non-blocking with respect to an inner side or a lower side of the film. 10. Film according to any one of the preceding claims characterized in that the second sealing regions (22) seal selectively only inside/outside.

Documents:

3614-CHENP-2006 CORRESPONDENCE OTHERS 27-08-2012.pdf

3614-CHENP-2006 CORRESPONDENCE OTHERS 19-11-2012.pdf

3614-CHENP-2006 CORRESPONDENCE OTHERS 28-09-2011.pdf

3614-CHENP-2006 AMENDED CLAIMS 28-03-2012.pdf

3614-CHENP-2006 AMENDED PAGES OF SPECIFICATION 28-03-2012.pdf

3614-CHENP-2006 EXAMINATION REPORT REPLY RECEIVED 28-03-2012.pdf

3614-CHENP-2006 FORM-1 28-03-2012.pdf

3614-CHENP-2006 FORM-3 28-03-2012.pdf

3614-CHENP-2006 OTHER PATENT DOCUMENT 28-03-2012.pdf

3614-CHENP-2006 POWER OF ATTORNEY 28-03-2012.pdf

3614-chenp-2006-abstract.image.jpg

3614-chenp-2006-abstract.pdf

3614-chenp-2006-claims.pdf

3614-chenp-2006-correspondnece-others.pdf

3614-chenp-2006-description(complete).pdf

3614-chenp-2006-drawings.pdf

3614-chenp-2006-form 1.pdf

3614-chenp-2006-form 5.pdf

3614-chenp-2006-pct.pdf