US3920123A

US3920123A - Packaging under heat-shrunk film

Info

Publication number: US3920123A
Application number: US452331A
Authority: US
Inventors: Nerio Martelli
Original assignee: Solvay SA
Current assignee: Solvay SA
Priority date: 1973-03-28
Filing date: 1974-03-18
Publication date: 1975-11-18
Anticipated expiration: 1992-11-18
Also published as: IT1005628B; DE2411564A1; CA1021736A; CH585135A5; JPS5026697A; BE812705A; ES200884U; ES200884Y; NL7404243A; FR2223983A5; GB1447732A

Abstract

A packaging comprising a film which is folded over edge to edge to form a loop and enclosing the product to be packaged and which is heat shrunk around the latter, and an edging made of a relatively rigid material glued to the edges of the film before shrinkage has an improved tear strength when the ends of the edges of the film are not glued to the rigid edging in order to enable them to contract freely during the shrinkage.

Description

United States Patent [1 91 Martelli Nov. 18, 1975 [30] Foreign Application Priority Data Mar. 28, 1973 France 73.11714 [52] US. Cl. 206/497; 206/45.33; 229/62; I 229/DIG. 12

[51] Int. C1. B65D 65/16; B65D 85/62 [58] Field of Search 206/497, 432, 45.33; 229/D1G. 12, 62, 55

[56] References Cited UNITED STATES PATENTS Rumsey, .lr. 206/45.33 Rumsey, Jr. 206/45.33

3,024,962 3/1962 Meister 229/62 3,142,436 7/1964 Heigl 229/62 3,203,621 8/1965 Wright 229/62 3,256,941 6/1966 Rivman 2.29/62 3,288,347 11/1966 Commisso et a1. 206/45.33 3,424,306 1/1969 Munck 206/432 3,687,282 8/1972 Owen 206/432 Primary Examiner-William T. Dixson, Jr. Attorney, Agent, or FirmSpencer & Kaye [57] ABSTRACT A packaging comprising a film which is folded over edge to edge to form a loop and enclosing the product to be packaged and which is heat shrunk around the latter, and an edging made of a relatively rigid material glued to the edges of the film before shrinkage has an improved tear strength when the ends of the edges of the film are not glued to the rigid edging in order to enable them to contract freely during the shrinkage.

5 Claims, 13 Drawing Figures Patent Nov. 18,1975 Sheet10f9 3,920,123

FIG. 1

US Patent Nov. 18, 1975 Sheet2of9 3,920,123

U.S. Patent Nov. 18,1975 Sheet3of9 3,920,123

FIG. 3

US. Patent Nov. 18, 1975 Sheet4of9 3,920,123

FIG. 4

U.S. Patent Nov. 18, 1975 Sheet 5 of9 3,920,123

U.'S. Pat nt Nov. 18, 1975 Sheet60f9 3,920,123

FIG. 6'

US. Patent Nov. 18,1975 Sheet70f9 3,920,123

FIG. 7

U.S. Patent Nov. 18,1975 Sheet8of9 3,920,123

FIG. 8

@QG @GO US. Patent Nov. 1 1975 Sheet90f9 3,920,123

PACKAGING UNDER HEAT-SHRUNK FILM Thepresent invention relates to a packaging under heat-shrunk film in which one of the sides is equipped with an edging made of a relatively rigid material.

Packagings of the same type are already known, from German Pat. Application 1,901,104 of 10.1.1969 in the name of UNION CARBIDE. These packagings are made from a rectangle of heat-shrinkable film. The rectangle is folded in two, edge to edge, and the two folds are welded on one another by means of a glue which can be activated by heat so as to form a tube under the weld as well as an edging. The articles to be packaged are placed inside the tube whilst the edging is covered over its entire length with a relatively rigid material such as cardboard. The whole is then heated so as to bring about the shrinkage of the tubular part. It is impossible for the edging, which is covered with a non-shrinkable rigid material, to contract. Because of this, two mechanically weakened linear ,zones are created in the shrunk film along the edging. Since, furthermore, these zones terminate at their two ends at. nonwelded edges of the film, there are great risks that the film will tear at these places.

In fact, it has been found that, when the covered edgings of the packages in question are used to transport them, to handle them and to present them for sale, a high proportion of packagings tear and lose their contents. When this happens, it has been observed that the tears always start at the ends of the edging and propagate along the latter.

SUMMARY OF THE INVENTION made of a relatively rigid material glued to the edges of the film before shrinkage, in which the ends of the,

edges of the film are not glued to the edging in order to enable them to contract freely during the shrinkage.

DETAILED DESCRIPTION OF THE INVENTION In order to produce the packagings of the invention, thin films are used which have been stretched, at least in one direction and preferably in two orthogonal directions, at a temperature at which the crystallites'can become oriented. If these films are reheated at the temperature at which the stretching was carried out, the orientation tensions are liberated and the film contracts and tends to return to its original dimensions. The extent of stretching, and consequently the degree of orientation and the capacity for contraction, is not critical as long as it is sufficient to make it possible to immobilize the packaged articles. The thickness of the film is not critical either as long as it is sufficient to sup port the weight of the packaged articles. lngeneral, this thickness is less than 1 mm, and most frequently less than 0.5 mm.

The films are made of any film-formingmaterial whatsoever which can be oriented by stretching. It is I which is heat-shrunk around the latter, andan edging propylene), thermoplastic polyesters (for example, polyethylene glycol terephthalate) and polyamides. The best results are obtained with films based on a polymer which contains at least mol% of vinyl chloride and which does not contain plasticizer (less than 10% by'weight and preferably less than 5%).

The edgings used within the scope of the invention are made of any relatively rigid flat material whatsoever. Cardboard is preferably used. However, it is also possible to make the edgings from a sufficiently rigid plastic.

In the packagings of the invention, the edgings are glued to the edges of the film before shrinkage. To do this, various methods can be used. For example, it is possible to employ an adhesive dissolved in a solvent which is removed by evaporation. If the film and the edging are made of materials which are suitable for the purpose, it is also possible to weld the film to the edging by local heating without employing any glue. However, in order to effect adhesion between the film and the edging, it is preferred to use an adhesive which can be activated by heat, of the type commonly called hotmelt. The use of these adhesives is well known in the art. They are generally based on vinyl resins.

Numerous embodiments can be envisaged in relation to the shape of the film and the manner in which it is used in the invention. The simplest method of working consists of starting with a rectangular piece of film which is folded over edge to edge in the form of a loop. The articles to be packaged are placed between the two folds thus formed. The edging is glued to the two superposed edges of the folded-over film.

In another embodiment, a sachet, open at the top, containing the articles to be packaged, forms the starting material. This sachet can consist of two identical flat faces welded on three sides or of a rectangle folded in two and welded at the two lateral sides. It can also be of parallelepiped shape and can thus possess a flat bottom and lateral sides.

Whatever the embodiment used, it is preferable that the bottom of the loop should not contain a weld but should be made by folding the film. In this way, packagings of improved mechanical strength are produced.

The edging used within the scope of the invention can be single or double. When it is single, it is either placed between the two edges of the film or glued to one of them which is itself glued to the other. When it is double, it can be made either of a single part and folded at its center or of two parts fixed one against the other.

The invention is further illustrated by the following.

FIG. 8: Diagrammatic front view ofa packaging after shrinkage.

FIG. 90: Profile view in cross-section of a single edging secured between the film,

FIG. 9b: Profile view in cross-section of a single edging secured to the outer surface of the sealed edges of the film,

FIG. 90: Profile view in cross-section ofa folded edging wtih one fold position between the film and the other on the outer surface of the film,

FIG. 9d: Profile view in cross-section of two single edging secured to outer surfaces of the film, and

FIG. 92: Profile view in cross-section ofa folded edging secured to outer surfaces of the film.

FIG. 1 represents a diagrammatic front view of the prepared packaging. In order to make the sketch clearer, the packaging is represented in the non-shrunk state and it does not contain any articles to be packaged. It consists of an edging l, for example made of cardboard, and of a transparent film 2, for example made of non-plasticized polyvinyl chloride.

FIG. 2 represents a profile view in cross-section of the same packaging.

FIG. 3 represents a plan view of the inside face of the opened out edging I. This edging is made from a rectangular piece of cardboard folded symmetrically along the line 8.

The film is also employed in the form ofa rectangular piece folded over to form a loop about the line 3 so as practically to superpose the upper edges. In the embodiment illustrated, the upper edges of the film are not glued to one another. The system for closing and gluing the edging is explained by FIG. 3 wherein strips of hot-melt adhesive, with which the edgings are provided before being pressed against the upper edges of the film, are represented. The strip 5 serves to join the edging firmly to one fold of the film and the strip 6 has the same function for the other fold. The strip 7 serves to glue the two side portions of the edging to one another; it does not come into contact with the film.

Although the film can be employed in the form of a tubular loop open at its lateral ends, it is nevertheless preferred to weld the ends 4 so as to form a bag which is closed on three sides and open at the top. This especially prevents dust from entering inside the packaging.

FIG. 4 represents the same packaging as FIG. 1, from the same angle, but after shrinkage around a packaged article consisting of a cellular plate 9 made from heatshaped expanded polystyrene on which fruit 10 is placed. FIG. 5 represents the same packaging seen in profile.

It is seen, in FIG. 1 that the upper edges of the film are not glued at their left and right ends to the edging which is moreover not so wide as the film. After shrinkage of the film, these parts of the edges which have contracted freely create gatherings of material at 11 (FIGS. 4 and 5), and this considerably increases the resistance to tearing at the ends of the edging.

In the embodiment illustrated in FIGS. 1 to 5, the strenghtening of the packaging is achieved by using an edging which is not so long as the upper edges of the film. In this embodiment, it is preferred that the edges of the film should project by at least 5 mm on either side of the edging. The best results are obtained when they project by at least 10 mm. Moreover, the strengthening effect is further improved by the fact that the two folds are welded laterally: There is thus no live section of the film in the vicinity of the edging which, under the effect of the weight of the packaged articles, could give rise to a tear.

It is also possible to use edgings which are the same length as the film before shrinkage. In this case, in order to achieve strengthening, it suffices not to glue the edging to the film over its entire length. This embodiment is illustrated by FIG. 6 wherein the edging, opened out and equipped with strips of glue as in FIG. 3, is represented. In this case, the strips of glue 5 and 6 must be stopped before the end of the edging as is represented in FIG. 6. In this embodiment, it is preferred that the end of the strip of glue should be at a distance of at least 1 mm from the ends of the edging. The best results are obtained when this distance is greater than 3 mm. After shrinkage, the packaging has the form indicated in FIG. 7. Here again, there is gathering of material 11, preventing tearing.

The effects of the above two embodiments can be combined in a preferential embodiment wherein an edging of length less than that of the edges of the film and strips of glue of length less than that of the edging are used simultaneously. Such a packaging is represented in FIG. 8.

Instead of using a double edging as in FIG. 1 to 8, it is possible to employ single edgings as represented in diagrammatic cross-section in FIGS. 9a and 9b. In the embodiment of FIG. 9b, the two edges of the film must be welded to one another by any means whatsoever. FIG. represents a new variant of the use of double edgings. FIG. 9d relates to the use of two single edgings which can be firmly attached to one another by any means whatsoever, for example clips.

An embodiment has been represented in FIG. 9e wherein the film adhers to a double edging folded over on the entire inner surface of the latter. This embodiment is particularly valuable when the articles to be packaged are very heavy. In this embodiment, the opening of the handle during shrinkage is prevented by fixing the two side portions to one another by any method whatsoever, for example clips. It is possible to pierce the two edges of the film right through by means of a single perforations; the sticking of the two side portions of the edging is thus achieved.

The shrinking of the film around the packaged articles is effected in accordance with well-known techniques by subjecting the packaging to a high temperature (preferably above C) for a few seconds.

In addition to the advantages which are common to all packagings under heat-shrunk film, the packagings of the invention possess advantages which are peculiar to them and which make them particularly valuable. Thus the edging can be used not only to identify the packaged products and to give various other pieces of information, but it can also serve as a handle for transporting and handling the packaging and for displaying it for sale. For this purpose, it can be equipped with openings which co-operate with the hand, or with perforations which make it possible to slip the packagings over rods which are perpendicular to them. These rods can themselves be fixed to vertical flat surfaces in display racks, or to trolleys for standardized transport. In the latter case, the trolleys can be stocked directly at the production site and it is possible to eliminate the manpower used to stock display racks by bringing the trolleys directly to the retail sites.

This advantage of the packagings of the invention is particularly marked in the case where the packaged articles are heavy. In this case, in fact, the use of the packagings of the prior art cannot be considered because there are far too many losses due to rupture of 5 the film along the edging.

The packagings of the invention can be used for packaging a very large number of products, and espeedging made of a relatively rigid material glued to the edges of the film before shrinkage, and the ends of the edges of the film are not glued to the edging in order to enable them to contract freely during the shrinkage.

2. Packaging according to claim 1, wherein the rigid edging is not as long as the edges of the film to which it is glued.

3. Packaging according to claim 1, wherein the rigid edging is of the same length as the edges of the film before shrinkage and is not glued to the edges of the film over its entire length. I

4. Packaging accordingto claim 3, wherein the edging is not glued to the edges of the film near its ends.

5. Packaging according to claim 1 wherein the rigid edging is of a length less than that of the edges of the film and the rigid edging contains strips of glue of a length less than that of the rigid edging.

Claims

1. Packaging comprising a film which is folded over edge to edge to form a loop which encloses the products to be packaged and which is heat-shrunk around the latter, said loop being closed on three sides by welding the lateral sides of the loop before shrinkage, an edging made of a relatively rigid material glued to the edges of the film before shrinkage, and the ends of the edges of the film are not glued to the edging in order to enable them to contract freely during the shrinkage.

3. PackagIng according to claim 1, wherein the rigid edging is of the same length as the edges of the film before shrinkage and is not glued to the edges of the film over its entire length.

4. Packaging according to claim 3, wherein the edging is not glued to the edges of the film near its ends.