Materials for forming composite packages and method of producing such packages

Abstract

The invention relates to materials and method for forming composite packages comprising a first flexible material (11) and a second relatively rigid material (12) which are connected together without the use of additional connecting materials. The connection is achieved by causing the flexible material (11) to be deformed to cooperate in tension with interrupted zones (19) of the relatively rigid material (12). Many different packages may be formed for a variety of uses but the invention is particularly suitable for connecting a heat shrinkable plastic body part to a paperboard or like sheet material end part.

Description

This invention relates to composite material and to packages formed by the combination of a first flexible material and a second relatively rigid material in which the first material includes a portion bounding a surface of the second material. Such a combination is particularly useful for forming a composite package utilizing the so called heat shrinking technique in which the flexible material is shrunk onto the relatively rigid material whereby the two materials are connected together so that the flexible material provides a body portion of the package and the relatively rigid material provides an end part of the package.

The combination of a flexible material such as sheet plastics and a relatively rigid material such as paperboard, or similar sheet material, to form a package is well known. However, in such known packages it is common practice to secure the plastics material to the paperboard by adhesive or by stapling the two materials together. This is a labour intensive procedure which is inefficient and tends to make manufacture of such packages costly. The present invention combines such composite materials, particularly in the manufacture of packages, to form a strong connection between the materials without the use of additional connecting materials to provide a cost effective product.

One aspect of the invention provides the combination of a first flexible material and a second relatively rigid material in which the first material includes a portion bounding a surface of the second material, characterised in that said surface is formed with at least one interrupted zone engaged by an adjacent overlaying part of the first material which part is deformed to cooperate in tension with said interrupted zone so as to hold the first and second materials connected together.

Another aspect of the invention provides a composite package comprising the combination of a relatively rigid material providing an end part of the package and a heat shrinkable plastics material providing a body part of the package and in which a portion of said end part is bounded by a continuous portion of said body part characterised in that the end part includes opposed boundary edges formed with interruptions and in that adjacent areas of said body part are deformed by heat shrinking said areas to cooperate in tension with said interruptions by which said body part is connected to said end part.

Yet another aspect of the invention provides a method of forming a composite package comprising a heat shrinkable plastics body portion and a relatively rigid end portion having opposed boundary edges formed with interrupted zones characterised by bringing together the end portion and the heat shrinkable body portion so that a part of the body portion bounds a surface of said end portion to cover said interrupted zones and causing areas of the body portion covering said interrupted zones to be heated whereby said areas of the body portion are drawn into tension across said interrupted zones by which said body portion is connected to said end portion.

Some embodiments of the invention will now be described by way of example, with reference to the accompanying drawings, in which:

FIG. 1 is a perspective front view of a composite package with a plastics body part shrink-fitted to a paperboard end part,

FIG. 1a shows a detailed view of one corner of the package,

FIG. 2 shows the top closure of the package in more detail,

FIG. 3 is a perspective view of a similar composite package,

FIG. 4 is a plan view of a pair of nested blanks each for providing the end part of the package illustrated in FIG. 3,

FIG. 5 is a front perspective view of a composite package having modified shrink fit openings,

FIG. 6 is a plan view of a blank for forming the end closure of the package shown in FIG. 5,

FIGS. 7 to 12 show various shapes of openings which may be used to provide means for shrink fitting,

FIG. 13 is a perspective view of a further composite package having an end part formed with projections to provide for shrink fitting,

FIG. 14 is a front view of another composite package having a body part provided by a plastics sleeve,

FIG. 15 is a plan view of a blank for forming the end part of the package shown in FIG. 14,

FIG. 16 is a plan view of a blank for forming a base end part of another composite package,

FIG. 17 is a similar plan view of a blank for forming a top end part of the same composite package, and

FIG. 18 is a perspective view of a composite package incorporating the end parts shown in FIGS. 16 and 17.

Referring to the drawings, FIG. 1 shows a composite package 10 made from a heat shrinkable plastics material formed to provide a body portion consisting of a bag 11, and a paperboard end part providing a top section 12 for the package. Other sheet materials similar to paperboard are also perfectly suitable for providing the end part of the package.

The top section 12 is illustrated in more detail in FIG. 2 and comprises an open-bottomed box formed by a pair of substantially parallel front and back walls 13 inter-connected by a pair of substantially parallel side walls 14 to form a rectilinear tubular structure. The top of the box includes side panels 15 hinged to the side walls 14 and a main closing panel 16 hinged to the front wall 13. Panels 15 and 16 cooperate to provide a reclosable top by which the package can be filled and by which access to the contents subsequently is gained. The top section 12 also includes an integral extension panel 17 formed with an aperture 18 by which the package 10 may be suspended at point of sale as shown in FIG. 1.

Each of the corners defined by the junction between walls 13 and 14 is interrupted with a pair of generally deltoid notches 19 providing openings into which overlaying portions of the bag 11 are drawn by heat shrinkage. The bag 11 initially has an open mouth which is marginally larger than the open bottom of top section 12 and the bag and top section are brought together so that the open bottom of the top section is overlapped and bounded by the mouth of the bag. The bag is then subjected to heat e.g. by means of hot air at least at those parts which overlay the deltoid notches 19 so that the plastics material shrinks and is drawn into the notched openings to become taut and thereby cooperate in tension to connect the bag 11 to the top section 12. A detailed view of one corner showing the shrink-fitted plastics is shown in FIG. 1a of the drawings.

Referring now to FIG. 3 of the drawings there is shown a composite package 20 similar to that described with reference to FIGS. 1 and 2 in which like parts are designated with like reference numerals but distinguished by the suffix "a." The package shown in FIG. 3 differs from that previously described in that the top portion 12a is extended to provide a pair of legs 21 each of which legs terminate at the base of the bag 11a so that the package is free-standing. Each of the legs 21 is formed by an extension of the side walls 14a together with an integral extended portion of each of the front and back walls 13a of the package. This construction leaves a window 22 formed in each of the front and back walls 13a.

FIG. 4 shows a pair of paperboard blanks 23, 24 for forming the top portion 12a of the package illustrated in FIG. 3. As can be seen the paperboard portion of the composite package 20 can be struck from a web of paperboard with minimum material waste in that the legs 21 of the one blank nest within the cut out windows 22 of the front and back walls of the other blank.

Referring now to FIG. 5 of the drawings there is shown a further composite package 25 which also is similar to the package 10 shown in FIG. 1 of the drawings. Like parts are designated with like reference numerals but distinguished by the suffix "b." Package 25 comprises a paperboard top portion 12b which is slimmer than the paperboard top portion 12 of package 10 in that the side walls 14b are of much reduced width as shown in FIG. 6. Hence, the package 25 includes trapezium opening 19b which extends across the whole width of the package thereby providing openings at opposite edges of the package which extend from the front wall to the back wall. Nevertheless, the plastics bag 11b is secured to the top section 12b of the package in a manner similar to that previously described with reference to the deltoid openings. FIG. 6 illustrates a paperboard blank from which the top section 12b of the package is formed from which it will be seen that the back wall of the package includes an extended wall 26 to add rigidity to the package and give better protection to the packaged articles 27.

FIGS. 7 to 12 inclusive show various forms of openings which may be struck from the paperboard part of a composite package to provide for the heat shrinkage of the plastics material. The deltoid notch illustrated at the left-hand side in FIG. 7 is that which is used at the corners of the packages illustrated in FIGS. 1, 2 and 3 of the drawings whereas the trapezium aperture shown at the left-hand side in FIG. 12 of the drawings is that which is used in the package illustrated in FIG. 5. The various shapes illustrated are by no means exhaustive, it being understood that many other suitable shapes could be utilized.

Destructive tests have been conducted in order to ascertain the strength and reliability of the connection between the paperboard and plastics material of composite packages according to this invention. In one such test a composite package in which a plastics bag was charged with a load of 1.0 Kg and having a pair of deltoid notches at each corner of the paperboard top portion was subjected to a jerk test in a suitable apparatus operating at a frequency of approximately 46 strokes per minute. It was found that with kraft 365 g paperboard and monorientated PE90.mu. plastics film each package tested withstood approximately 1100 strokes prior to failure of the connection between paperboard & plastics.

Referring now to FIG. 13 of the drawings there is shown a further composite package 28, similar to package 10. Like parts are designated with like reference numerals but distinguished by suffix "c." The top portion 12c is similar to that shown in FIG. 2 of the drawings and comprises a parallel front and back walls 13c connected together by spaced side walls 14c. The top of the box includes side panels 15c hinged to the side walls 14c and a main closing panel 16c hinged to front wall 13c. Panels 15c, 16c cooperate to provide a reclosable top by which the package can be filled and by which access to the contents subsequently is gained. The top section 12c also includes an integral extension panel 17c. In this embodiment, the notches 19 have been replaced by projections comprising tabs 29 struck from the paperboard blank. Each of the corners defined by the junction between walls 13c and 14c is formed with a pair of outwardly projecting tabs 29 which provide the interrupted zones by which the bag is secured to the top section 12c. In this construction, when the bag 11c is subjected to heat at those areas which overlay the tabs 29, the plastic material shrinks at least in the vicinity of the tabs 27 so that the plastics is drawn taut across each of the tabs to form areas of tension by which the bag 11c and paperboard top 12c are connected together. It will be appreciated that a variety of tab shapes may be struck from the paperboard other than the generally rectangular tabs 29 illustrated in the drawings. For example, the tabs may comprise a series saw-tooth serrations struck from the blank although many other shapes may be suitable.

FIG. 14 of the drawings illustrates a further composite package 30. In the package 30 the body part is provided by a plastics sleeve 31 which is shrink fitted to the top part 12d of the package. The paperboard top part 12d is illustrated in more detail in FIG. 15 of the drawings from which it will be seen that the side walls of the top have been dispensed with so that the top part basically comprises a front and back wall 13d, and an extension portion 17d by which the completed package can be suspended at point of sale. Deltoid notches 19d are struck from the blank at the edges of the front and back walls so that when the top portion is completed notches for shrink fitting the sleeve 31 are provided at opposite edges of the top portion. In a modified version (not shown) the back wall may be dispensed with, in which case the notches provided for shrink-fitting may comprise notched out areas of the opposed edges of the paperboard. Package 30 is particularly suitable for the packaging of flat articles such as that shown and in a further modification may comprise an extended strengthening wall (not shown) such as the panel 26 described with reference to FIG. 6.

FIG. 18 of the drawings show a further package 32 in which the body part of the package also comprises a plastic sleeve as in the previous embodiment. However, unlike the package 30 of the previous embodiment this package is particularly suitable for the packaging of folded bulky items and includes a paperboard base element 33 in addition to a paperboard top element.

The paperboard base element 33 is shown in more detail in FIG. 16 of the drawings whereas the paperboard top element 34 is shown in more detail in FIG. 17 of the drawings. Referring to FIG. 16 the blank for forming the base element 33 comprises a central panel 35 to which is foldably joined side panels 36, 37 along transverse fold lines 38, 39 respectively. The panel 36 includes a pair of foldably joined corner panels 36a, 36b and similarly the panel 37 includes foldably joined corner panels 37a, 37b. The central panel 35 has foldably joined along its longitudinal edges a pair of flank panels 35a, 35b respectively which are hinged to the main panel 35 along fold lines 40, 41 respectively. The fold lines 40, 41 extend the whole length of the blank and also provide the fold lines by which the corner panels are foldably joined to their respective end panels 36 and 37. Deltoid openings are struck from the blank along fold lines 40 and 41 to provide notches 42 in the erected base part 33 to provide for heat shrinkage of the plastics material as previously described.

To erect the blank into the base end part 33 of the composite package, the flank panels 35a, 35b are folded up in the same direction about fold lines 40, 41 respectively so as to bring the flank panels perpendicular to the centre panel 35. Similarly, the end panels 36, 37 are folded upwardly in the same direction as the flank panels about their respective fold lines 38, 39 and subsequently the corner panels 36a, 36b, 37a, 37b are overlapped against the upstanding flank panels 35a, 35b and secured in position. Thus the erected blank is brought into the configuration of an open topped box or tray and is used to provide the base part of the composite package 32 shown in FIG. 18.

The top closure 34 of the package 32 is depicted in FIG. 17 of the drawings. This top closure 34 fundamentally is similar to the base tray end part 33 shown on FIG. 16 with the exception that a two part handle structure has been interposed between centre panel 35' and flank panel 35a. The handle structure comprises a pair of handle panels 43, 44 which are mirror images of one another about a central fold line 45. Other parts of the top closure similar to like parts of the base tray are designated with similar reference numerals. The handle panel 43 is foldably joined to the centre panel 35' along fold line 46 and the handle panel 44 is foldably joined to the flank panel 35a' along fold line 47.

The plastic sleeve 48 of the composite package 32 is heat shrink fitted to both the base end part 33 and the top end part 34 by means of the deltoid notches 42, 42' by causing the plastics material to shrink in the areas overlaying the notches so as to provide the connection as previously described. It is of course, necessary to fill the package before the top closure 34 or the base closure 33 is connected with the plastic sleeve 48. To provide access to the contents of the package a tearaway panel section 49 is provided in the central panel 35'.

It is envisaged that it may not be necessary to provide openings, as shown, in each corner of the top and/or base elements of the package but in some cases it may be sufficient to provide such openings only in the diagonally opposite corners of each end part. Moreover, it also is envisaged that the notches need not be completely struck out from the blank so as to provide an opening but the material may only be scored leaving the central part defined by the score lines weakened but still attached to the paperboard. Nevertheless, the plastics material when shrink-fitted will still tend to be drawn into the areas defined by the scored notches in order to provide the means by which the plastics is secured to the paperboard. Such a construction may be desirable where it is necessary to protect the contents of the package from being adhered to the plastics material drawn into the notched areas of the paperboard.

Although the composite packages described have referred to the use of a heat shrinkable plastics material, it is also envisaged that other suitable material may be used. For example, material which can be shrink fitted other than by means of heating is within the scope of the invention. It is also envisaged that a material which is stretchable but yet retains some degree is resilience would be suitable. In this case the material could be initially maintained in a stretched condition during introduction of the paperboard or other similar sheet material. When the first material is released it should be sufficiently resilient to engage at least the interrupted zones of the second material such that the two materials are held connected together.

Claims

1. A reclosable package of composite material comprising in combination a top section (12) of paperboard and a bag (11) of heat shrinkable film material extending from said top section and adapted to accommodate a product, said top section comprising a tubular structure formed from angularly related walls and having a top closure and being open at the lower end thereof, said bag being of a length substantially greater than that of said top section from said lower end to said top closure so as to provide a major portion of said package, said top closure being formed from panels (15, 15, 16) hinged to the top edges of said walls and arranged to provide a reclosable opening, said bag being attached to the lower portion of said top section whereby the mouth of the bag overlaps adjacent outside portions of said walls so that the bag is held open by the top section which thereby provides access to said bag for filling or for removal of the content, said top section being provided with notches (19) at the junction between said walls and overlapping portions of said bag being locally deformed by heat shrinking to cooperate in tension with said notches so as to hold the bag and the top section connected together.

2. The package according to claim 1 wherein at least one of said walls has an extension (26) projecting into said bag to support said product.

3. The package according to claim 11 further characterized in that said top section (12) is of rectangular cross section.

4. The package according to claim 1 further characterized in that said top closure includes an extension panel (17) by which the package may be suspended at the point of sale.