US3183800A - Method of forming a cover for a package - Google Patents

Description

y 13, 1935 R. A. FARRELL ETAL A 3,183,800

METHOD OF FORMING A COVER FOR A PACKAGE Original Filed Feb. 26, 1963 2 sheetssheet l INVENTORS ROBERT :4. Fflll-LL GEmEGE V. SkouJRdNS/(I BY ATTOPfifY y 13, 1955 R. A. FARRELL ETAL 3,183,800

METHOD OF FORMING A COVER FOR A PACKAGE Original Filed Feb. 26, 1963 2 Sheets-Sheet 2 INVENTORS RoaegT ,4. FARRELL GEORGE V. JKpwRoNS/{l BY United States Patent Ofiice areas Patented May 18, 1965 3,183,800 MLETHOD GI FORMING A COVER FOR A PACKAGE Robert A. Farrell, Menasha, and George V. Skowronski, Neenah, Wis., assignors to American Can Company, New York, N.Y., a corporation of New Jersey Original application Feb. 26, 1963, Ser. No. 261,566, now Patent No. 3,158,491, dated Nov. 24, 1964. Divided and this application Nov. 14, 1963, Ser. No. 323,718

3 Claims. (Cl. 9336) This invention relates to a heat-sealed leakproof package. More specifically, the invention relates to a hermetically sealed package, having an opening means therein, for the packaging of prepared foods, such as potato salad, sandwich spreads, and frozen foods. This application is a division of Serial No. 261,566 filed February 26, 1963, now Patent No. 3,158,491, issued Nov. 24, 1964.

In the food merchandising industry it is particularly important to have packages which are hermetically sealed, have suflicient rigidity of construction for stacking during shipment and can be readily opened. In addition, if the packages are to be displayed, it is advantageous to have a window in the top for easy viewing of the contents without destroying the airtight seal and tamperproofness. Furthermore, it is important that the package components be shipped in stacked and nested condition to the product packager to save storage space prior to the formation of the completed package.

The package is formed from a rigid receptacle portion, such as a tapered plastic tray, having a bottom and continuous side with an outwardly extending continuous flange around the entire perimeter at the upper edge thereof and a separate cover portion which is heat-sealed to the upper surface of said flange after the receptacle portion is filled. The cover portion comprises frangible material, such as paperboard, having a heat-scalable coating, such as polyethylene, on the inner surface thereof. Lines of weakness in the frangible material define both a removable panel providing a window and opening means to gain access to the contents of the package. The polyethylene, in addition to providing a sealing medium, serves to provide a liquid impermeable closure.

The particular objects and advantages of the invention will be made clear from the following description in connection with the accompanying drawings, in which:

FIGURE 1 is a diagrammatic representation of a method for continuously converting suitable materials into blanks for use as cover portions of food packages,

FIGURE 2 is a top view of one of the blanks produced according to our method,

FIGURE 3 is a bottom view of the blank of FIGURE 2,

FIGURE 4 is a perspective of a food package made according to the present invention, 1

FIGURE 4A is a partial sectional view taken along line 4A4A of FIGURE 4 showing the superposed layers at the perimeter of the package,

FIGURE 5 is a perspective view of the food package having the window panel removed,

FIGURE 6 is a perspective view of the food package having the opening means partially removed, and

FIGURE 7 is a perspective view of the food package having the opening means and window portion removed and the contents exposed. i

Referring more particularly to FIGURE 1, there is shown a continuous method for converting a frangible material, i.e., paperboard, and a heat-scalable material, i.e., polyethylene, into composite blanks, such as the one depicted in FIGURES 2 and 3. Initially, a web of paperboard 10 is unwound and the leading edge threaded through the rolls in the manner shown in FIGURE 1. The paperboard is fed through applicator roll 11 and back-up roll 12, denoting generically a multi-color press, for printing the web with any desired indicia. The applicator roll 11 transfers the ink from an ink bath 13. After passing through the rolls 11 and 12, a pattern of release agent is applied to the unprinted side of the blank by applicator roll 14 in conjunction with back-up roll 15. The bath 18, from which the release agent is transferred to applicator roll 14 by means of pick-up roll 17 and transfer roll 16, is shown on the opposite side of the web from applicator roll 11 to emphasize the fact that the release agent is applied on one side of the web, while the printing is applied to the other. In the composite blank, shown in FIGURE 3, the area covered by the release agent is indicated by the stippling. Any suitable means, such as gravure cylinder, may be employed for applying the release agent. A variety of release agents may be employed, the choice being determined by the heat-seala'ole material to be applied to the paperboard. For instance, when polyethylene is the material to be applied to the web, the following coatings are particularly desirable since they give high gloss and clarity to the polyethylene as well as excellent release properties to the paperboard:

(l) A solution of 60% xylene and 40% of a mixture of: 98% DOW PS3 polystyrenea low molecular weight polystyrene produced by the Dow Chemical Company, and 2% Slipeze-a fatty acid amine commercial release agent produced by Fine Organics, Inc.

(2) A solution of 86% blended, volatile organic solvents and 14% 1/2 Second Butyratea cellulose acetate butyrate produced by Eastman Chemical Co.

The printed and coated web 10 then passes through a first cutting station comprising tensioning rolls 19, 25, eccentric synchronizing rolls 20, 24 for feeding the web to and from the cutting means 22 and tensioning rolls 21 and 23 immediately adjacent the cutting means. As the web is advanced through the cutting station, the eccen tric synchronizing rolls 20, 24 facilitate intermittent starting and stopping of the web coordinated with the reciprocating action of the cutting means 22. The first cut produces all the cutting and creasing lines impressed in the blank exclusive of the outer edge, as shown in FIGURES 2 and 3. Included in the first cutting and creasing step are partial cut line 46, which extends inward from the printed side only about halfway through the thickness of the paperboard, cut lines 41, angled lines of weakness 42, score line 45 and cut lines defining cut out areas 54 and 55.

The web 16 next passes over idler roll 25 and around drum 28. An extruder 26 positioned above the nip formed by. idler roll 25 and drum 2,8 extrudes a film of polyethylene- 61 onto the traveling web on the side having the release coating thereon. All of the cut lines are covered and sealed by the extruded coating material. The thickness of the extrusion coating, generally between one and two mils, varies with the material employed and with the degree of strength and, protection required.

I the perimeter of the paperboard.

The composite web then travels over idler roll 29, feed rolls 3t), 31, constant tension roll 32 and idler roll 33 into a second cutting means 34 which separates the web into composite blanks A shown in FIGURES 2 and 3. As the blanks leave the second cutting means 34, they are transferred to an endless moving outfeed belt 35 rotating around pulley 36 and then removed for packing. The blanks are stacked, boxed and shipped to the product packager for use with receptacle portions to form completed packages.

The composite. blank A comprising paperboard and polyethylene is divided by partial cut line 4%, cut lines 41, angled cut lines 42 and score line as into edge panel 50, tear strip 51, center panel 52 and pull tab 53. A tearaway element 51a, shown in FIGURES 2 and 4, is defined by partial cut line 40 and the portions of angled cut lines 42 parallel to said partial out line 4! Edge 43 of the center panel 52 and cut lines 41 define an area 54 in which the paperboard has been removed to facilitate removal of the center panel 52 for display purposes. Similarly the free edge of pull tab 53 and cut lines 44 define an area 55 in which the paperboard has been removed to facilitate grasping of the pull tab 53 for removal of the tear strip. As is readily apparent from FIGURE 3, the polyethylene layer is coextensive with The. food package is formed by first filling a receptacle portion such as tapered tray 60 shown in FIGURE 4,

aisasoo with the commodity to be packaged. The receptacle portion comprises a bottom panel and continuous side walls connected therewith. The upper edges of the side Walls terminate in a continuous outwardly extending flange portion tia'which is preferably smooth and flat at its upper surface and preferably extends in a substantially horizontal plane. Trays made from materials, such as high density polyethylene, are particularly suitable since they provide a rigid construction at an economical price and can be heat-sealed readily to a variety of materials, such as 'high or low density polyethylene. 1 After the tray 6t) is filled with product 76) (see FIGURES 5-7), the blank A, which is the cover, is placed on the tray. The

the tear strip 51 is removed causing peeling of the upper surface of the cover. Partial cut line limits the extent of outward peeling so that tear element 51a is uniformly removed down to about one-half the thickness of the paperboard while the remainder of the cover remains intact.

It is obvious that materials other than those described previously may be employed. For instance, the receptacle portion may be made of polystyrene or polypropylene and the heat-sealable material may be any of a variety of coated cellophane. The choice of the particular materials will be dictated by the properties of each. In order to insure a hermetically sealed package, the heat-sealable material on the cover must readily seal to the receptacle portion. Also the release agent should not cloud the heat-sealable material so as to detract from the appearance of the Window for display purposes. The opening means will not function properly unless the degree of adhesion between the heat-scalable material and the frangible material of the cover is sufficient to prevent their separation when the tear strip is removed.

If desired, the receptacle portion may be made of coated paperboard and have a foil lining on the inner surface. Then, after opening, the package can be immediately inserted in the oven and the contents baked in the receptacle portion.

The present invention provides a tamperproof hermetically sealed package, which can readily be stacked for shipping purposes. The package provides a'window panel which may be removed for display purposes and also a tear strip which provides ready access to the contents. Since the frangible cover material never contacts the contents in the completed closed package, there is no wicking of the product. The receptacle may in some instances be'used to bake the contents of the package without the necessity of employing a separate vessel. The

outer edge of the outwardly extending flange portion 63a of the tray, as shown in FIGURE 4A, coincides with the outer edge of the blank or cover. The cover is placed with the polyethylene layer 61 in contact with-the flange portion 60a. Heat and pressure are then applied around the entire perimeter of the cover. portion to heat-seal the polyethylene layer 61 and the flange portion 6% together. Upon completion of the sealing step'the contents of the package are hermetically enclosed. The completed package is shown in FIGURE 4.

The center panel 52 can be removed for the displaying of the contents 76 by grasping at the edge 43 and pulling upward to detach along lines of weakness 4-1. Because of the release agent on the inner surface of the cover portion (see the stippled area of FIGURE 3), the center panel 52 can easily be removed without disturbing the underlying layer of polyethylene (see FIGURE 5); i In addition, the polyethylene exposed has a high gloss and high degreeof clarity due to the particular release agent employed. The completed package having the center,

panel 52 removed is shown in FIGURE 5.

The packageis opened and the contentsexposed by grasping the pull tab SS andlifting and pulling the tear strip 51 back upon itself, as shown in FIGURE 6. The

extruded polyethylene 61 adheres to the underside of the a tear strip 51. and is removed along 'with tear strip.

After completely removing the tear strip'5l the contents ofrthe package are exposed, as shown inFIGURE 7.

The relationship between the thickness of the paperboard and the thickness of the polyethylene is governed bythe need for the polyethylene to tear before the paperboard breaks or peels'back thereby preventing opening. The

to remainiattached to thetear-away element 51a when use of a preformed plastic tray for the receptacle portion reduces the equipment required by the packager for setting up cartons from blanks. In addition to providing an attractive appearance to the completed package, the

tray. can be reused by the consumer for storage.

It is to be understood that the size and the shape of the package and the materials from which it is formed may be varied in numerous ways by those skilled in the art without departing from the spirit of the invention.

. We claim: 7 V

1; The method of forming a cover to be used with a V receptacle portion to form a leakproof package with an portions betweenthe individual angled cut'lines .42 tend opening means, which method comprises passing a web of frangible material through a first cutting station and imposing in {the web pairs of spaced, substantially parallel, closed lines pf. weakness defining tear strips, coating said Web with a material which is heat-activatable, passing said web through a second cutting station and producing cover-defining cuts and separating the resulting individual covers from the remainder of the web.

2. The method of forming a cover to be used with a receptacle portion to form a leakproof package with an opening means, which method comprises passing a web of paperboard through a first cutting station'and imposing in the web pairs of spaced, substantially parallel, closed lines of Weakness defining tear strips, extruding polyethylene over an. entire web. surface, passing said web through a second cutting station and producing "cover-defining cuts, and continuously separating the rein predetermined areas; passing the web through a first cutting stationand imposing in the web pairsof spaced,

'subs'tantiallyparallel, closed-lines of weakness defining tear strips, the innermost line of Weakness of each pair surrounding one of said areas and being essentially coincident with the outer edge thereof; coating the side of the web opposite the release agent bearing side with a material which is heat-activatable; passing said web through a second cutting station and imposing cover-defining cuts, and continuously separating the resulting individual covers from the remainder of the web.

References Cited by the Examiner UNITED STATES PATENTS 5 3,004,697 10/61 Stone.

3,097,574 7/63 Kuchenbecker 93-36 3,110,434 11/63 Lindaet al.

FOREIGN PATENTS 2/63 Great Britain.

FRANK E. BAILEY, Primary Examiner.

FRANKLIN T. GARRETT, WHITMORE A. WILTZ,

Examiners.

Claims (1)

1. THE METHOD OF FORMING A COVER TO BE USED WITH A RECEPTACLE PORTION TO FORM A LEAKPROOF PACKAGE WITH AN OPENING MEANS, WHICH METHOD COMPRISES PASSING A WEB OF FRANGIBLE MATERIAL THROUGH A FIRST CUTTING STATION AND IMPOSING IN THE WEB PAIRS OF SPACED, SUBSTANTIALLY PARALLEL, CLOSED LINES OF WEAKNESS DEFINING TEAR STRIPS, COATING SAID WEB WITH A MATERIAL WHICH IS HEAT- ACTIVATABLE, PASSING SAID WEB THROUGH A SECOND CUTTING STATION AND PRODUCING COVER-DEFINING CUTS AND SEPARATING THE RESULTING INDIVIDUAL COVERS FROM THE REMAINDER OF THE WEB.

Images