Package seal

[57] ABSTRACT

The invention discloses a packaging development providing enhanced resistance to splitting or opening of a seam or seal in a multi-ply wall flexible film package. A chub package having a cylindrical multi-ply wall of flexible film gathered at the end by clenched metal bands is set forth, the package having a seal formed at offsetting marginal strips on the inner and outer plies of the multi-ply wall. In a preferred method of forming a package, a marginal strip on each ply is offset from an adjacent edge of the adjacent ply prior to forming the seal and the seal is formed by heat sealing the marginal strips to opposite edges of the same ply.

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PACKAGE SEAL

This invention relates to a package having a seam or seal and to the method of making the seal of enhanced resistance to splitting or tearing.

The present invention is described hereinafter in connection with, but is not to be construed as being limited to, the formation of a collapsible wall dispenser of the kind fully disclosed in U.S. Pat. No. 3,477,614 to Runge entitled “Dispenser,” which issued Nov. 11, 1969. This dispenser includes a so-called chub package which is generally tubular in shape with a longitudinally extending seal or seam and clenched metal bands securing gathered ends of the package. A wraparound strip is applied to the exterior of the package and supports a dispenser nozzle having an orifice through which a knife point may be inserted to pierce the package wall. The contents of the package are extruded through the pierced wall and nozzle by squeezing and collapsing the package wall.

Such packages may contain various products such as, for ²⁰example, food products which may be extruded from the nozzle in streams with predetermined, fanciful shapes. Many products may require a considerable squeezing force on the package to extrude the product, particularly if the product is cold, with the result that considerable outwardly directed forces are applied against the longitudinally extending seal of the package tending to split or to open the same. The package wall is formed of a flexible film comprising a plastic sheet, but such packaging materials also are subject to experiencing tear propagation, i.e., a continuation of the tear, from the puncture ³⁰made at the area of the nozzle. When the nozzle is located adjacent the longitudinally extending seal, such tears are likely to propagate into the seal and may cause the seal to fail.

Accordingly, a general object of the invention is to provide an improved seal for a multi-ply package wall and a method of ³⁵making the package and seal.

Other objects and advantages of the invention will become apparent from the following detailed description taken in connection with the accompanying drawings in which:

FIG. 1 is a perspective view of a dispenser and package embodying the novel features of the invention;

FIG. 2 is a cross-sectional view illustrating the offset relationship of the plies prior to forming into the tubular shape of FIG. 1;

FIG. 3 is an enlarged cross-sectional view of the package of FIG. 1; and

FIG. 4 is a diagrammatic illustration of a method of forming the package illustrated in FIG. 1.

As shown in the drawings for purposes of illustration, the invention is embodied in the package 11 having a multi-ply wall 13 which is suitably formed to package a material therein and joined along a longitudinally extending seal or seam 15 with edges of the wall overlapped in a manner to provide enchanced resistance at the seal 15 against splitting or tearing. Such enhanced strength characteristics for the seal 15 are particularly important for a package on which is attached a dispensing nozzle 17 by means of a strip 19. The pressure for dispensing the contents of the package in a stream 20 of fanciful cross section with a manually exerted squeezing applies unusual pressure at the seam 15. More specifically, the illustrated package 11 is a so-called chub package which is of the type used to dispense a stream 20 of processed cheese or other extrudable materials upon puncturing the package wall 13 by inserting a sharp knife point through an orifice 21 in the nozzle 17.

Briefly, the preferred method of making a package with a strong, longitudinally extending seal 15 includes the steps of laterally offsetting an inner ply 23 from an outer ply 25 of the flexible film material comprising the wall 13 of the package to provide elongated, marginal strips 27 and 29, as best seen in FIG. 2, along the longitudinal edges of each of the respective plies. That is to say, the marginal strip 27 of the inner ply extends laterally outwardly of edge 30 of the outer ply 25 and an opposite marginal strip 29 is provided by the outer ply which extends laterally outwardly beyond the edge 32 of the inner ply 23. The multi-ply film material is formed into a tubular shape and filled with the material to be dispensed. The longitudinally extending seal 15 for the package is formed by 5 joining the outer ply marginal strip 29 to an overlapped edge 31 of the outer ply 25, as best seen in FIG. 3, to form a first or outer seal; and by joining the interior ply marginal strip 27 to an overlapped edge 33 of the inner ply 23, as best seen in FIG. 3, to form a second or inner seal. Suitable end seals for the ^υ package are made by application of metallic clenching bands 35 (FIG. 1) which tightly gather the package wall 13 together to form the sausage-like chub packages. As will be explained in greater detail in the preferred embodiment of the invention, ₍₅ the inner and outer plies are each formed of a web of flexible film material such as saran 38 having a heat sealable coating 40 thereon for autogenously heat sealing due to the heat of the packaged product, while a third or intermediate seal 41 between the inner ply 23 and the outer ply 25 is formed by radio frequency heat sealer means 43 at the location of the dashed line.

Referring now in greater detail to the individual elements of the invention, the preferred inner and outer plies 23 and 25 have two layers, namely a layer 38 of saran and a layer of heat sealable material 40. Particularly good results have been obtained with a saran layer 38 coated with a heat sealable material 40 sold by Dow Chemical Company of Midland. Michigan under the trade name of Dow No. PZ 1620.19. These inner and outer plies 23, 25 of heat sealable coated saran are preferably about 1 mil in thickness and are about 5 % inches in width. It is to be understood that the inner and outer plies may be made of other film materials and coated with other heat sealable coatings such as, for example, Elvax vinyl resins sold by E. I. du Pont de Nemours Co. of Wilmington, Delaware. Alternatively, the film materials themselves may be of heat sealable material. In this preferred embodiment, and as shown in FIG. 3, of the invention the outer ply 25 is disposed with its heat sealable coating 40 facing inwardly so that when formed into a tube, the heat sealable coating along 40 its offset marginal strip 29 abuts the saran layer 38 along the opposite edge portion 31 of the outer ply 25. The heat sealable coating 40 on the inner ply 23 faces outwardly so that when formed into a tube the heat sealable coating on its offset marginal strip 27 abuts the saran layer 38 along the opposite edge ⁴³ portion 33 of the inner ply 23.

The terms inner and “outer” are used in the relative sense as there may be additional exterior or interior plies, or for that matter an intermediate ply, associated with the flexi₅₀ ble film used to form the package wall 13. In the preferred embodiment of the disclosed package the wall 13 is provided with additional strength against bursting or tearing by the inclusion of an intermediate reinforcing ply 45 of a thin film of polyethylene. Preferably, the polyethylene is located between ₅₅ the superimposed areas of the respective inner and outer plies 23 and 25 and has a width substantially less than the width of either the inner or outer plies. The polyethylene ply 45 is positioned so that it does not extend either into the first or second seal to interfere with the heat sealing at the marginal strips 27 60 and 29 or into the third, intermediate seal 41. A suitable polyethylene is a thin film about 0.015 inches in thickness and about 4 ’Λ inches in width.

Referring now briefly to the diagrammatic illustration of FIG. 4, the preferred manner of making and filling the chub 65 packages 11 with a flowable product such as processed cheese will be described. The inner ply 23 may be formed from a continuous web of film material which is stripped from a supply roll 50 and fed forwardly along a path to a packaging station 51. The polyethylene intermediate ply 45 may also be in web 70 form and disposed beneath the inner ply 23 and stripped from a supply roll 53. The outer ply 25 may likewise be in web form and stripped from a suitable supply roll 55 and disposed beneath the intermediate ply 45. The respective plies 23, 25 and 45 are arranged relative to each other and the inter75 mediate ply 45 is sandwiched between the other plies. In this

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4 instance the heat sealable coatings 40 of the inner and outer plies 23 and 25 are facing toward the intermediate ply 45. With the edge of each of the inner and outer plies laterally offset to form % inch wide marginal strips, the plies are fed forwardly and formed by a former 57 into a generally tubular 5 shape with the marginal strips 27 and 29 of the respective plies arranged in generally overlapped arrangement in the manner illustrated in FIG. 3 with their respective interior edges 42 and 44 substantially coplanar and spaced slightly from each other. At this time, heated processed cheese 59 is being discharged 10 from a nozzle 60 into the center of the formed tube. The hot cheese will immediately raise the temperature of the heat sealable coatings 40 at the marginal strips to cause the heat sealable coatings to heat seal to the marginal edge portions 31 and 33 of the respective plies. This will also hold the 15 polyethylene intermediate ply 45 against sliding relative to the inner and outer plies. Simultaneously with the formation of the above marginal seals, it is preferred that a radio frequency type of heat sealer 43 at the packaging station 51 form the intermediate heat seal 41. 20

After filling the tube with cheese, the clenching bands 35 are clamped tightly to gather together the package wall 13 and seal these package ends against release of the cheese product when the side wall is squeezed to dispense its contents. Thus, a relatively wide seam 15 having first, second and third seals or 25 seal areas is obtained to provide resistance to a separating of the heat seals when a squeezing pressure is applied to the package wall 13.

As stated above, the usual manner of using the dispenser is to insert a sharp knife point through the orifice 21 in the noz- 30 zle 17 to puncture the package wall 13. As the material squeezes through the puncture, the puncture made by the knife point tends to expand although it is limited to a certain degree by the encircling band 19 which carries the nozzle. Particularly when the nozzle is secured to the package wall at 35 the location adjacent the seam 15, the seam will be called upon to resist further tear propagation in the direction circumferentially of the package.

Advantageously, the seam 15 is formed with only a single ply 25 having its edge 63 (FIG. 3) exposed at the seam 15. 40 Under conventional techniques of forming a seam for such a package, the edges of both the inner and outer plies would be exposed and the result would be a seam with an edge twice as thick as the edge 63 for the illustrated package. A thick seam edge may interfere with attaching the strip 19 to the package 45 wall. More specifically the preferred manner of attaching the strip 19 to the package is to provide the band with an inner surface coating of pressure sensitive adhesive and to roll the package 13 onto this adhesive coating. If the thin exposed seam edge 63 is only a single ply in thickness, this edge 63 30 does not interfere even when the edge 63 first engages the adhesive, with rolling of the package on the strip. Thus, the thinner edge 63 facilitates rolling and adhering of the chub package to an adhesive on the wrapper strip 19, and the formation of smooth, non-wrinkled appearance for the wrapper $$ strip 19.

From the foregoing, it will be seen that the illustrated package is formed with a seal means 15 having a longitudinally extending inner seal adhering overlapped edges of the inner ply, a longitudinally extending outer seal adhering overlapped edges of the outer ply and a centrally disposed longitudinally extending seal intermediate the overlapped inner and outer plies. The inner and outer seals provide additional strength to the overlapped central intermediate seal.

While a preferred embodiment has been shown and described, it will be understood that there is no intent to limit the invention by such disclosure but, rather, it is intended to cover all modifications and alternate constructions falling within the spirit and scope of the invention as defined in the appended claims. 70