Patent Application
20170341798
The present invention relates to packaged flexible polymer films and packaging systems for flexible polymer films.
In the prior art, flexible films formed from polymeric materials and/or plastics are typically packaged at the manufacturing site as rolls, with the film wound onto a cylindrical supporting carrier formed from rigid, non-compressible plastic, cardboard or the like (called a core). The roll is then enclosed and contained in a box, bag or other packaging to protect the film during transport and provide an aesthetically pleasing appearance to customers. For some products, for example films for application to windows installed in automobiles and buildings, the flexible films are often packaged during manufacture in large and heavy “bulk” rolls; however, product distribution channel requirements demand that film wound on such bulk rolls be unwound and then rewound into smaller “commercial” rolls for shipping and eventual sale. By way of example, such window films are often wound on bulk rolls of around 3000 meters at manufacture and then repackaged for sale to customers in relatively short rolls wherein 30.5 meters or less of material is wound on a 76.5 mm diameter plastic core. Highly specialized flexible films, such as metallized films for use in medical testing devices, electronic devices, displays and the like, are also packaged as rolls of material wound on a core.
So that the film can be wound onto the core properly for commercial rolls, the leading end of the film nearest the core is typically adhered to the core using a double-sided self-adhesive strip that runs transversely along the full width of the film at the leading end. When the film is unwound from the commercial roll for use, the 1-3 meters of the film packaged nearest the core when originally wound thereon, is often found to be unusable as a result of a repeating imprint, sometimes referred to as an “embossment”, created in the initial wraps of the film around the core. Because the flexible film is relatively thin, in the order of 60-400μ, this imprint effect is replicated in several of the innermost layers of wound film close to the core. These imprints are caused by one or more factors typically present in the packaging process and system. There are several reasons why film suffers from imprints. These include:
Film tension. Mechanical requirements demand that tension is applied during winding in order to be able to process film through the winding machine.
Film Edge. The leading end of the film runs across the width of the wound film and is cut with a relatively sharp vertical edge that forms a ridge at the interface of the film's leading end with surface of the core.
Adhesive Strip. The double sided adhesive strip has a minimized (typically 25-50μ) but nonetheless potentially impactful thickness and can create an even more severe imprint than the end of the film. It presents two ends rather than one and the general evenness of the thickness of adhesive strip over the entire area of adhesive, particularly hand-applied aerosol pressure sensitive adhesives, can be very poor.
Core surface. The core surface itself may have defects or minute contaminants that impact its uniformity and smoothness.
These imprints are typically permanent such that, if use of the film is attempted, defects in the final product's functionality and/or aesthetic appearance are highly likely. With respect to window films, installation of this portion of the film from the roll on a vehicle or building window is often the source for consumer complaints and warranty claims.
One prior art attempt to overcome the embossment problem included chamfering the leading end of the film so that the cut end of the film is angled or gradually reduced in thickness rather than presenting a sharp vertical end. It is difficult with such thin materials, however, to achieve any uniform angled cut of this kind, particularly at such a shallow angle as would be necessary to materially reduce the impact of the leading end on the imprint problem. Other prior art methods to reduce imprinting involve changing aspects of the core, for example (i) milling an angled depression into the length of the core such that the leading end of the film seats in the depression in the core so as to present a smooth surface over which subsequent layers of film wrap during winding onto the core or (ii) modifying the core to include a slit or other feature to “trap” and/or hold the leading end of the film within the core cavity. Such solutions are, however, typically not cost effective as they add expensive machining, molding, slitting or other high-precision steps to the core manufacturing process and create the need for cores that are highly customized to match individual film types and thicknesses. Further, they also present challenges in properly adhering the leading end of the film to the core so that the roll can be properly wound.
Despite these prior art efforts, embossments remain a significant source of waste and inefficiency for the flexible films industry. Aside and apart from the embossment problem, the films industry is in lock step with industry in general as it seeks out improved, sustainable packaging systems and for its products that reduce excess packaging material and waste.
In a first aspect, the present invention relates to a coreless flexible film packaging system. The system includes (i) a containment cylinder including a cylindrical wall defining first and second cylinder end apertures and an interior film containment area; (ii) a film feed slot in the cylindrical wall extending longitudinally along the containment cylinder; and (iii) a supply of flexible film wound about itself to form a film roll having a central cylindrical cavity, with the roll comprising a leading end and a terminal end and contained within said interior film containment area.
In another aspect, the present invention further relates to a coreless containment package for containing a supply of flexible film comprising a leading end and a terminal end and wound about itself to form a film roll. The package includes (i) a containment cylinder for containing the film roll, with the containment cylinder including a cylindrical wall with an outer surface and the cylindrical wall defining first and second cylinder end apertures; and (ii) a film feed slot in the cylindrical wall extending longitudinally along said containment cylinder.
In yet another aspect, the present invention relates to a method for packaging a flexible film including: (i) providing a containment cylinder, the cylinder including a cylindrical wall and a film feed slot extending longitudinally along the containment cylinder, with the cylindrical wall defining first and second cylinder end apertures and an interior film containment area; (ii) feeding the flexible film into the interior film containment area through the film feed slot; and (iii) winding said flexible film about itself to form a film roll having a central cylindrical cavity lined by the film, with roll contained within the interior film containment area.
Further aspects of the invention are as disclosed and claimed herein.
As shown in
As shown in
In a particularly preferred embodiment, the coreless containment package 10 further includes caps 60 at each of said first and second end apertures 45 and 50. Caps 60 may be formed from materials well known to one of ordinary skill, for example thermoplastic polymers, using well-known manufacturing techniques such as for example injection molding and hot-press molding. In this embodiment, the outer surface 40 of the cylindrical wall 35 of the cylinder constitutes the exposed surface of a coreless flexible film packaging system as described below. In comparison to the prior art flexible film packaging systems wherein film wound on a core formed from rigid, non-compressible plastic, cardboard or the like which is then contained in a box, bag or other packaging to protect the film, this embodiment of the present invention provides an advantageous, environmentally friendly and cost-saving alternative system that uses significantly less packaging material and accordingly reduced packaging waste. In this embodiment, at least one of the caps 60 is substantially transparent so as to facilitate visual inspection of the film. Outer surface 40 may also optionally include at least one of printing or graphics so as to provide information and/or an aesthetically pleasing appearance to customers.
In a second and related aspect, the present invention relates to a coreless flexible film packaging system. In its most general sense and as shown in
The system 75 preferably further includes seal strip 57 affixed to said containment cylinder 30 at said outer surface 40. Preferably the seal strip 57 is located adjacent to film feed slot 55 and most preferably is also affixed to the terminal end 19 of the supply of said flexible film 15. Seal strip 57 may be applied to the core and formed in situ from materials well known to one of ordinary skill, for example a pressure sensitive, hot melt or curable adhesive composition. Seal strip 57 may also be a separately formed adhesive tape adhered to the core.
In a particularly preferred embodiment, the system 75 further includes caps 60 at each of said first and second end apertures 45 and 50. Caps 60 may be formed from materials well known to one of ordinary skill, for example thermoplastic polymers, using well-known manufacturing techniques such as for example injection molding and extrusion. In this embodiment, the outer surface 40 of the cylindrical wall 35 of the cylinder constitutes the exposed surface 80 of the coreless flexible film packaging system. In comparison to the prior art flexible film packaging systems wherein film is wound on a core which is then enclosed in a box, bag or other packaging to protect the film, the system 75 provides an advantageous, environmentally friendly and cost-saving alternative that uses significantly less packaging material and accordingly reduces the amount of packaging waste. Further, it will be readily appreciated that the film feed slot of the system is also a dispensing port for the contained flexible film in this embodiment.
In this embodiment, at least one of the caps 60 is substantially transparent so as to facilitate visual inspection of the film. Exposed surface 80 may also optionally include at least one of printing or graphics so as to provide information and/or an aesthetically pleasing appearance to customers.
The flexible film for use with the present invention may be any flexible film, web or the like typically packaged concurrent with or after manufacturing as a roll. Non-limiting examples include PET, polypropylene, PVC, polyurethane and the like. Preferably, the flexible film is “self-winding”, defined herein to encompass films that exhibit a natural tendency to wind or curl about themselves without application of external force. For example, many films utilized in the window films industry develop during manufacture what is known in the art as “MD (machine direction) curl”, a tendency of the film to curl in the direction in which the film travels during process operations such as dyeing, coating, laminating and slitting. This tendency can be particularly relevant in flexible films with multiple laminated layers or applied coatings and is created as tension that is applied during the processing steps elongates the film and creates strain in the layers that varies for example by layer type and thickness. For example, MD curl in commercial window film constructions generally towards the scratch-resistant coating.
In a third aspect, the present invention relates to a method for packaging a flexible film. The method of the present invention includes: (i) providing a containment cylinder that includes a cylindrical wall with an outer surface and a longitudinally extending film feed slot, with the cylindrical wall defining first and second cylinder end apertures and an interior film containment area; (ii) feeding the flexible film into the interior film containment area through the film feed slot; and (iii) winding said flexible film about itself to form a roll having a central cylindrical cavity lined by said film, with the roll contained within the interior film containment area.
Suitable equipment for operation of the method of the present invention is shown in
Preferably, the flexible film is a self-winding film which winds about itself to form the roll without externally applied force and the winding step therefore includes self-winding of the flexible film. For example, in the embodiment where the flexible film is a window film that includes a scratch-resistant coating, winding would include self-winding of the flexible film toward the scratch resistant side. In typical window film constructions, this will leave a release liner side, a more slippery surface, to slide against the inside surface of the cylinder during winding.
Optionally, the winding step may include applying external winding force to the film. In one particular embodiment, the optional winding force is applied by a rotatable axle 85 such that the winding step of the method present invention includes (a) removably inserting a rotating axle 85 into the interior film containment area 52 and (b) removably attaching said leading end 18 of flexible film 15 to the axle 85. In this embodiment, the method of the present invention most preferably includes the further step (c) of releasing the leading end of the film from the axle at the conclusion of said winding step and removing the rotating axle from interior film containment area. In a particularly preferred embodiment, rotating axle 85 is a perforated axle connected to a vacuum/pressure source such that the removably attaching step (b) above preferably includes applying vacuum to the flexible film during winding and the releasing step (c) preferably includes releasing the vacuum when winding is complete. The releasing step (c) may optionally also include applying positive pressure to the flexible film to facilitate release of the leading end of the flexible film 15 at the conclusion of the winding step when winding is complete. Axle 85 and the nip roller speed should be controlled and adjusted so that the flexible film 15 does not wind up around the axle 85 but is simply held by it at and close to the leading end 18.
As movement of materials such as flexible films can cause static build up, it will be understood that the method of the present invention preferably includes electrically grounding the flexible film and the containment cylinder.
The foregoing description of various embodiments of the invention has been presented for purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise embodiments disclosed. Numerous modifications or variations are possible in light of the above teachings. The embodiments discussed were chosen and described to provide the best illustration of the principles of the invention and its practical application to thereby enable one of ordinary skill in the art to utilize the invention in various embodiments and with various modifications as are suited to the particular use contemplated. All such modifications and variations are within the scope of the invention as determined by the appended claims when interpreted in accordance with the breadth to which they are fairly, legally, and equitably entitled.
