US 3358900 A
Abstract available in
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Description (OCR text may contain errors)
DBC. 19, 1967 R R. PERDUE 3,358,900
PACKAGING Original Filed May l0, 1963 United States Patent 6 Claims. (Cl. 229-30) ABSTRACT OF THE DISCLOSURE A foldable blank for forming a carton having a continuous lateral flange at its upper perimeter.
This application is a division of my prior copending application Ser. No. 279,550 filed May 10, 1963.
This invention relates to methods and articles useful in the packaging art. More specifically the invention relates to a preformed, foldable blank used in preparing a carton enclosed thermoplastic film covered product and to a semi-continuous or continuous process for forming the carton enclosed package from such blanks.
In the packaging of various food items such as sliced bacon, dried or dehydrated soups, eggs, coffee, milk and the like there are presently two widely used production methods. One such method involves placing the product (eg. bacon slices) on the base portion of a pre-scored paperboard wrapper, folding the wrapper about and locking it in place with clips, adhesives, locking tabs or the like, and then enclosing the carton or box thus formed in a sheet of transparent heat scalable thermoplastic film, c g., polyethylene. This method obviously requires an excessively large amount of expensive hand labor and of wrapping film. In another commonly used method the product is packaged in a pouch of fexible transparent film (which may be evacuated or gas iiushed and then hermetically sealed) and the pouches thus formed are inserted into a printed paperboard carton for shipment to the wholesaler or retailer. This latter method as presently practiced required two separate packaging operations and two separate machines for performing the same.
It is an object of this invention to provide a novel method for producing carton protected film packages similar to those previously produced, but at a much lower overall cost.`
Another object of the invention is to provide a prescored foldable blank especially adapted for use in the new packaging method.
Yet another object is to provide a method for continuousv production of a carton protected vacuum or gas hushed film package at high production rates.
Other objects and advantages of the invention will be apparent to those skilled in the art after consideration of the following detailed description, the appended claims and the accompanying drawings.
In the drawings:
FIGURE 1 is a perspective View illustrating schematically the operative steps in the method of this invention, and means for performing the same;
FIGURE 2 is a plan view of a foldable blank constructed in accordance with the invention;
FIGURE 2a is a partial plan view of an alternative blank construction;
FIGURE 3 is a perspective view of the blank of FIG- URE 2 after it has been erected;
FIGURE 4 is an elevational view, in cross section, of the package made in accordance with the teachings of this invention; and
FIGURE 5 is an enlarged sectional view of the encircled portion V in FIGURE 4.
The blank used in the invention will first be described. As best seen in FIGURE 2, the prescored, unfolded blank comprises a central rectangular base portion 10 and a side wall portion 11 extending laterally from each edge of the base. The length of each side wall portion is equal to the length of the base edge from which it extends. Each side wall portion has an equal width b. At the extremity of each side Wall there is a flap or flange 12 or 13. All aps have substantially the same width a. Preferably the length of each of at least one pair of oppositely disposed flanges (e.g. flanges 12) is greater than the length of each of the other pair of oppositely disposed anges (e.g. 13). This increased length is equal to twice the width a, one half of which is disposed at each end of the longer flanges. This particular dimensional relationship is required in order to result in an erected blank having a continuous lateral flange at its upper perimeter of essentially equal width, all parts of which are on essentially the same plane. If desired the same result could be achieved by using the construction illustrated in FIGURE 2a. In this alternative embodiment each end of each flange has a triangular tab 60, each of which is a 45 triangle. The equal legs of the triangle each have a length a and the tabs are positioned so that one of these sides is integral with the end of the flange with which it is associated.
To permit viewing package contents in some packages, e.g. bacon or luncheon meat packages, there preferably is a window aperture 14 cut through the base portion, usually but not necessarily somewhere in the middle of such portion. The area of this aperture may range up to about 80 percent or so of the total area of the base portion. The aperture perimeter can have any desired shape and is not restricted to the substantially square configuration illustrated in the drawings. For other types of products, eg., frozen dehydrated soups and vegetables, dehydrated or ground coffee, etc.; in which event no window is provided in the blank of this invention.
When the packaging method (to be described more fully) utilizes a vacuum forming step, it is desirable to provide further apertures 16 in the base portion ofthe blank in order to obtain suitable conformation of the vacuum drawn film to the contour of the erected blank.
Score lines 17, 18, 19, 20 and 21, 22, 23, 24 are provided to assist in erecting the blank into an openmouthed, li-anged, rectangular carton 25 (as shown in FIGURE 3). The anges 12, 13 of this container are provided with heat activatable adhesive 26 extending completely around the upper perimeter of the container. The adhesive can be applied in known manner either before or after the carton blank is erected.
The best mode now contemplated for carrying out the method of this invention will be described in connection with FIGURE 1, which illustrates schematically the steps involved. Briefly the method comprises setting up the previously described blank in a female mold and, if necessary, applying heat-activatable adhesive to the fianges; heating a thermoforamable thermoplastic film to temperatures in the forming range; covering the open mouth of the blank with the heated film thereby activating the afore-V said adhesive; thermoforming the heated film into a substantially conforming liner for the blank; at least partially cooling the subassembly thus formed to set the adhesive and formed film liner; filling the lined blank with product; covering the mouth of the film lined, filled blank with a material that can be heat sealed to the film liner; and finally heat sealing the cover material to the lined blank around the flanges thereof. When the product is a food material preferred (but nevertheless optional) additional steps include evacuating the filled, lined blank before completion of sealing the cover material; or, in lieu of, or in addition to, evacuating, flushing or back filling with an inert or innocuous gas.
FIGURE 1 shows schematically the operations involved in performing the method in a semi-continuous manner, i.e., a manner which, while involving intermittent motion still gives continuous production. In the illustrated embodiment the fiow of oper-ations proceeds from left to right.
A blank 25a is fed from a continuous die cut pre-scored web 27, severed from the web and placed into register with each of the female mold forms 29 that are carried on endless driven conveyor 28. Alternatively, individual pre-severed and stacked blanks 25a could be supplied from a suitable holding magazine equipped with a dispenser-indexer device.
ln any case, the blank is pressed into conformity with the mold by carton forming plug 31'. The plug is suitably shaped so as to erect the blank 25a into a set up carton 25 (as illustrated, e.g. in FIGURE 3) the flanges 12 and 13 of which extend around the upper perimeter of mold 29.
In the event that the anges have not been pre-coated with adhesive 26, such coating application is performed by adhesive coater 32.
Preparatory to the next step in the operation, a thermoforamable thermoplastic film 46 such as polyethylene, polypropylene, polystyrene, etc., is drawn from feed roll 33 over heated roll 34 and then over the top of the mold 29 which now carries set-up blank 25. The temperature of heating roll 34 and the speed of travel of the film over the roll is chosen so as to heat the film to thermoforming temperature. Preheating the film to these temperatures prior to bringing it over the mold also results in the additional function of activating the thermo-activatable adhesive 26 on the flanges of the erected carton.
The assembly next passes to a thermoforming station where the overlying hot film is formed into conformity with the cavity of the erected carton 2S. This may he done by use of any one of the Well known thermoforming methods. Preferably the forming is accomplished by vacuum drawing the hot llm into ther carton cavity by reducing the pressure beneath the female mold cavity via a suitable suction box 35 or other like suitable device. During the vacuum drawing operation the film 46 is held in place over the mouth of the erected carton by hold-down device 37, and by tension on the film as it is drawn from feed roll 33. Vacuum is drawn through the erected blank via the window 14 and apertures 16. In the absence of these apertures the vacuum can be drawn through the slits at the corners of the erected blank or through a plurality of performations which may be provided along the score lines 17, 18, 19, and 20 or in the body portion 1f) of the blank.
The film-lined blank now passes to a filling station where product to be packaged is inserted into the thermoformed film pocket. Filling can be accomplished manually or mechanically as, e.g., by filling devices such as feed tube 36 or other like known devices. As the lined blank travels from the forming station to the filling station it is cooled by ambient atmosphere (or by other suitable means, if desired) to temperatures where the film pocket and the thermo-activatable adhesive become permanently set.
After filling, the assembly moves to a covering and closing station. |Here a suitable heat sealable cover material 39 such as heat sealable thermo-plastic film, or paperboard having a heat sealable plastic coating, is drawn from feed roll l38 over the filled carton. Sealing head 41 is lowered over the covered carton and heat seals the cover material to the film liner 46 around the fiange perimeter of the erected carton. If desired or necessary for any particular product, the sealing head can, in known manner, be provided with suitable means for evacuating, gas fiushing or otherwise altering the internal atmosphere of the package before the cover is completely sealed. It
will be obvious that the covers could be supplied from a stack of pre-severed, individual sections rather than being drawn from a continuous Web.
The sealed packages move towards the discharge end of the conveyor in the form of a continuous band. The cover material, if fed in web form, is severed between molds by cutting device 42 after which the individual separated packages are ejected from the molds 29 and transferred to take off conveyor 43.
Any one of several known drive arrangements can be used to obtain the necessary intermittent motion of conveyor 28 that is required to perform the individual operations that take place `at the various stations. Fully continuous operation can be achieved by constructing the apparatus in such manner that the various elements such as the forming plug 31, hold-down device 37, sealing head 41, etc. travel with the conveyor for a short distance while performing their function and then reciprocate counter to the conveyor travel direction to begin operation on the next succeeding carton.
The package produced by this invention is illustrated in FIGURES 4 and 5. It will be noted that in normal usage the package is inverted so that cover material 38 forms a supporting base and the erected blank 25 forms a surrounding cover. In the embodiment illustrated the base of the package is comprised of paperboard sheet 49 having a coextensive continuous coating 40 of suitable material that is relatively impermeable to gases and moisture vapor. This base is hermetically heat sealed to the thermoformed plastic film liner46 along the fianges 12 and 13. The periphery of the liner is in turn adhesively sealed to these flanges by adhesive 47. Product 48 eg., a stack of sliced luncheon meat, is protectively packaged 'between the liner and base. Carton 51, the sides 52 cf which are of approximately same height as height of the product stack, surrounds and partially covers the top of the film enclosed product. Window aperture 53 in the top 54 of the carton permits viewing of product by a prospective purchaser.
The foregoing description is necessarily quite detailed. It will be understood that various modifications may be made in size, shape, sequence of operations, etc. For example it is possible to use adhesives other than those which are heat activatable, e.g., pressure sensitive adhesives. -In the latter case the film liner can be secured to the erected blank by the pressure applied in the final sealing step.
It will be obvious that the film liner may comprise a laminate of different thermoformable plastics if desired for any particular purpose. Such laminates include, but are not limited to, those composed of separate bonded layers of polyethylene and a Saran-type polymer, polyethylene and a polyester (such as the polyethylene terephthalate sold commercially under the trade name Mylar), polyethylene and cellophane or any other like combination of thermoplastic materials. Similar considerations apply to the cover material which may if desired be composed of laminate of paperboard, aluminum foil and polyethylene, or paperboard, a Saran-type polymer and polyethylene or the like in order to have better moisture barrier properties and lower oxygen permeability.
Those skilled in the art will recognize other equivalent procedures and/ or materials.
What is claimed is:
`1. A foldable blank composed of paperboard or the like and useful for manufacture of carton-protected film packages comprising:
(a) a rectangular base portion;
(b) a rectangular side Wall portion extending laterally from each edge of the base portion; each such side wall being coextensive with the edge from which it extends and having an equal width;
(c) a rectangular flange extending laterally from the free edge of each side wall portion; each having an equal width; one opposing pair of said flanges having a length equal to the length of its respective side Wall plus a rectangular extension on each end equal to the width of the llange; the other opposing pair of lianges having a length equal to their respective side walls; and (d) means along the jointures of the base portion and each Wall portion and along the jointures of each wall portion and its respective flange permitting folding of these portions with respect to each other. 2. Foldable blank as defined in claim 1 wherein said means (d) are score lines.
3. Foldable blank as defined in claim 1 wherein (a) a window aperture is provided centrally of said base portion; (b) a small aperture is provided adjacent to but spaced from each of the four corners of the .base portion. 4. tFoldable blank as delined in claim 2 wherein there are spaced plural perforations along each of the score 6 lines between the base portion and the side wall portions. 5. Foldable blank as deined in claim 1 wherein each dlange has a coextensive coating of adhesive over its upper surface.
6. Foldable blank as dened in claim 5 wherein said adhesive is heat activatable.
References Cited UNITED STATES PATENTS 2,328,563 y9/ 1943 Lichter 229-30 3,077,294 2/ 1963 Barrez 229-6 3,104,012 9/ 1963 Beamish 206-46 3,119,540 1/'1964 Schenk et al. 229-30 X 3,124,915 3/1964 Arneson 53-27 3,135,455 6/1964 Santangelo 229-30 3,195,425 7/1965 Taggart 93-3601 ,DAVID M. BOCKENEK, Primary Examiner.