Patent Application
20100307948
The invention pertains to the art of packaging and, more specifically, to packaging of various products between first and second plastic films in a form, fill and seal system wherein one of the films is shrinkable, but not the other film.
Mainly because of cost efficiencies and packaging versatility, vertical and horizontal form, fill and seal packaging systems have become increasingly popular, even in the food industry. For instance, vertical form, fill and seal systems (VFFS) have been used in connection with making sealed bags, such as potato chip and other types of snack bags, while horizontal form, fill and seal (HFFS) packaging systems have been known for use in effectively packaging frozen foods. By way of an example, a HFFS system can be employed to create product cavities or pouches in a lower film, with the pouches being filled with frozen dough products and sealed with an upper film. Prior to fully sealing the pouches, a vacuum is typically drawn in order to reduce the available headspace of the package. Although evacuating the headspace is appropriate for frozen dough products, employing a vacuum on a refrigerated dough product would inherently destroy nucleation sites for leavener in the dough and, consequently, the overall product.
Another problem with packaging dough in a flexible package, particularly refrigerated dough which has been pre-cut into products to be cooked, such as biscuits, concerns the use of the flexible package as the sole and primary package. Basically, the dough will deform in response to gravity and external pressure/weight applied to the dough. This could occur even in loaded shopping bags. Obviously, the deformation of the dough would undesirably result in inconsistently shaped cooked products. Certainly, this problem can be a concern in connection with numerous products, including products outside the food art. Although this problem could be solved by further packaging the flexible package in a carton or the like, this option would negate the cost savings.
Based on the above, it would be advantageous to enable various products, including soft, deformable food products such as both low and high pressure dough products, to be effectively stored and sold in flexible packaging, while minimizing any product deformation.
The invention is directed to a method for packaging products between first and second films in a form, fill and seal system, as well as the associated product, wherein one of the films is heat shrunk at least 5% about the product while the other film exhibits no appreciable shrinkage. In making a product in accordance with an aspect of the invention, a flexible product receiving cavity is initially formed in a first film and a product is loaded into the cavity. A second film is positioned across the loaded product receiving cavity and then joined to the first film about a peripheral portion of the product cavity to create a package containing the product. In accordance with a main aspect of the invention, the package is heated to cause the first film to shrink about the product while the second film exhibits no appreciable shrinkage.
When the first film is shrunk without permitting venting from inside the package, i.e., the package is completely sealed, an external pressure is effectively applied about the package which, in effect, limits the extent that the package and product can be physically deformed, thereby enhancing the stability of the overall product. Basically, the applied force is essentially transferred to static pressure within the package. However, if the first film is shrunk while accommodating venting from inside the package, the majority of the product can be tightly wrapped by the first, shrinkable film. In either case, as the second film is specifically designed not to shrink, product information, advertising and similar indicia can be applied to the second film, even prior to joining the first and second films, without the risk of the indicia being visually distorted, regardless of any product deformation.
Additional objects, features and advantages of the invention will become more readily apparent from the following detailed description when taken in conjunction with the drawings wherein like reference numerals refer to corresponding parts in the several views.
With initial reference to
In general, thermoforming devices such as that employed in connection with forming station 18 are widely known in the art and do not form part of the present invention. However, for the sake of completeness, it should at least be understood that the function of forming station 18 is to receive heated lower film 5 between lower cavity mold 21 and upper cavity mold 30 at which time the movement of lower film 5 is temporarily stopped, projection molds 32 are mated with recessed cavities 23 in order to reshape lower film 5 to include product cavities 20. To aid in this shaping operation, fluid communication lines 25 can be hooked to a vacuum source in order to draw lower film 5 against recessed cavities 23 as well as to subsequently apply a positive pressure to aid in removing the formed product cavities 20 from lower cavity mold 21 after the thermoforming process is complete.
Once product cavities 20 are formed in lower film 5, lower film 5 advances to a loading or filling station generally indicated at 40. At this point, it should be recognized that filling station 40 can take various forms without departing from the invention. As illustrated, filling station 40 includes a vertical loading unit 42 including a platform 43 from which extend various loading arms 44 used to transport products, such as that indicated at 46, into the individual product cavities 20.
After products 46 are loaded into product cavities 20, lower film 5 is advanced to a sealing station 52. At this point, depending on the product being packaged, it may be potentially advantageous to reduce package headspace volume associated with product cavities 20 prior to completing the packaging operation. Certainly, the headspace can be reduced in various ways. For instance, an external force can be applied to lower film 5, such as by providing either a fixed or movable plate (not shown) which abuts lower film 5. In another embodiment, a housing including a pressure chamber at sealing station 52 can be employed, such as disclosed in co-owned U.S. Patent Application entitled “HFFS Packaging Method Employing Positive Differential Pressure” filed on even date herewith and incorporated herein by reference. In any case, whether package headspace is reduced or not, at sealing station 52, a second or upper film 56 is provided over first film 5 and sealed thereto. As will become more fully evident below, the product cavities 20 can be completely sealed or some accommodation for venting can be provided, such as a small seal gap. In the embodiment shown, second film 56 is drawn from a payout reel 57 and delivered through a printing unit 60. Printing unit 60 is used to provide product information, advertising and similar indicia directly on upper film 56 as generally indicated at 61 in
Important in accordance with the invention is that first or lower film 5 is made of a heat shrinkable material, while the material employed for second or upper film 56 is non-shrinking, i.e., exhibits no appreciable shrinkage upon heating. More specifically, film 5 will shrink in accordance with the invention a minimum of 5% and up to 50%, preferably 7-38% and more preferably 13-27%. Known films can be utilized for this purpose, such as CURLON Grade 9506-J, 9580-W and 9581-W flexible films produced by Curwood, a Bemis Company, for the food industry. These films can vary in thickness between approximately 2.75-6.0 mils, although even thicker films could be utilized. The percentage of film shrinkage is not only a function of the particular film employed, but also the applied temperature. To date, application temperatures ranging from about 80° C. to about 115° C. have been effectively employed. Obviously, a different material is used for non-shrinking film 56. Again, there are various known film products having the necessary criteria, including 1834-K (which is a clear film) and 1839-K (which is a white film) made by Curwood. These films can also range in thickness, while a 3.5 mill 834-K film was found to be effective.
When product cavities 20 are completely sealed, shrinking film 5 establishes an external pressure which is effectively applied about package 68, in effect limiting the extent that package 68 and product 46 can be physically deformed, thereby enhancing the stability of the overall product. This arrangement can be particularly beneficial when packaging a soft or pliable product, such as a refrigerated dough product. Basically, the applied compression force is essentially transferred to static pressure within the package 68. If venting is permitted, the first film 5 will shrink to conform to the shape of the majority of the product in the cavity 20. In either case, as the second film 56 is specifically designed not to shrink, the product information, advertising and similar indicia 61 can be applied to upper film 56, even prior to full or partial sealing of package 68, without the risk of the indicia 61 being visually distorted. This non-distortion of indicia 61 is perhaps best illustrated in comparing package 68 of soft, deformable refrigerated dough before and after being shrunk as shown in
Although described with reference to certain embodiments of the invention, it should be understood that various changes and/or modifications can be made to the invention without departing from the spirit thereof. For instance, although the referenced embodiment illustrates the shrinking station to be employed following the sealing station, since only the lower film is being shrunk, it is possible to reposition the shrinking station before the sealing station even though certain advantages in reduced headspace would be compromised. In addition, although the invention has been described with particular reference to packaging a food product, particularly a deformable, soft food product such as a refrigerated dough which can benefit greatly from pressurized packaging, it should be recognized that the invention can be employed with a wide range of products which can be packaged under pressure, evacuated or just placed in a protective wrapping. Although the invention should not be considered limited in this regard, other food products can include sardines, asparagus, soup, pet food, fruit snacks, cereals such as Cheerios®, and chips, while a host of non-food products, including stuffed toy animals, decks of cards, sponges, toilet paper, towels, clothing and play dough, can be advantageously packaged. Furthermore, the invention can be employed with horizontal or vertical form, fill and seal systems, as well as other flexible packaging systems. In any event, the invention is only intended to be limited by the scope of the following claims.
