[0001] The present invention relates to carrier bags constructed of thermoplastic film and
having an insulating interlining,
*particularly for the transport of chilled or frozen foodstuffs.
[0002] A variety of carrier bags are known and proposed in which two layers of thermoplastic
film are used to encase a third layer of insulating material. Although elaborate constructions
can be devised in which the bag is a three-dimensionaT structure with gussets and
side walls, it is difficult to obtain a simple flat two-dimensional bag which can
accommodate a large volume of frozen food, but can at the same time remain sealed.
By a two-dimensional bag is meant a bag in which front and back faces are joined at
the side and bottom edges without an intervening side wall or bottom panel. Bags of
this type are obviously very much cheaper and easier to construct as they can be produced
by simple welding of superimposed folded thermoplastic film. Many shopping carriers
are constructed on this principle.
[0003] It has now been found that a particular construction of bag having a closure of a
type known as such, but mounted in a particular way. can be simply formed, can be
packed flat. but can accommodate bulky food packages while remaining sealed.
[0004] According to the present invention there is provided an insulated carrier bag comprising
an outer bag of plastic film including integral handle apertures the outer bag being
bonded to an inner bag of plastic film along top edges thereof below the handle apertures
so as to enclose therebetween an insulating material and further comprising an upstanding
flange of plastic film inside the outer bag along each of the said top edges and bonded
to. or integral with, the inner bag. the flanges being a pair of opposed flanges including
a linear resilient closure,
[0005] Both theinner and outer bags can be formed of conventional thermoplastic film used
for shopping carriers, typically a polyalkylene film such as polyethylene or polypropylene.
The film may be transparent or opaque, although it is particularly preferred that
the inner bag is transparent and the outer bag is opaque or metallised.
[0006] The bags may be constructed in the usual manner by superimposing sheets or tubes
of film folded in the required arrangement and then cutting and welding to produce
the appropriate bag edges. In a particularly preferred embodiment, the outer bag has
top edges formed by a folded down portion of film: bottom edges formed by a simple
fold or crease in the film and side edges formed by welding. The integral handle apertures
are conveniently stamped at the top of the outer bag, conveniently in the area of
double film provided by the folded down portion.
[0007] The inner bag is bonded to the outer bag along its top edges. Conveniently it is
free elsewhere, but may be bonded along the side edges if required.
[0008] The insulating material lying between the two bags is conveniently a sheet material,
especially a "bubble film" type of material comprising two layers of film bonded together
and trapping firmly inflated film in a regular array. In a preferred construction.
the insulating material is also bonded along the top edges of the inner bag and is
free elsewhere.
[0009] A particularly important aspect of the bag according to this invention lies in the
particular mounting of the closure. Each internal surface of the outer bag, at about
the line of bonding with the inner bag, is provided with an upstanding flange of plastic
film. so that when the bag is flat, the two upstanding flanges form an opposed and
superimposed pair. At a distance from the bond line and parallel therewith, the flanges
of plastic film are provided with complementary parts of a linear resilient closure.
A preferred type of closure comprises a rib and a groove which are adapted to interlock
when pressed together. This type of closure is known as a Minigrip closure (registered
Trademark). Other types include simple sliding clasp fasteners.
[0010] By placing the rib and groove on an upstanding flange between the handles of the
outer bag, the seal can remain closed even when a relatively heavy load is placed
in the bag. When required, the closure can be opened by simply peeling apart the pair
of flanges. In a particularly preferred embodiment, the upstanding flanges are integrally
formed with the inner bag.
[0011] A preferred embodiment of the bag according to the present invention will now be
described with reference to the accompanying drawings in which
Figure 1 is a general view of the bag and
Figure 2 represents a section along AA in Figure 1.
[0012] An outer bag 1 is formed from a sheet of opaque metallised polyalkylene film folded
in half lengthways and with the edges turned in to produce an area of overlap 2. Inside
the outer film is disposed a folded layer of babble film 3. Inside this is disposed
a polyalkylene film 4 also folded in half lengthways and bearing on its margins attached
strips of heavier gauge polyalkylene 5 and 6 bearing embossed rib and groove 7 and
8 parallel to the edges.
[0013] In a welding process all the layers are bonded together in the vicinity of point
A so that bags of the appropriate width are provided by cutting the film transversely
at appropriate intervals and welding the edges, at least of the outer bag. Carrying
handles can be stamped in the overlap portion 2 of the outer film 1.
[0014] In order to close the bag the upstanding flange portions 5 & 6 of the inner bag are
pressed together so that the rib and grooves 7 and 8 interlock. To open the bag the
top edges of the inner bag are simply peeled apart. Alternatively, the ribbed and
grooved flanges 5 and 6 may also be provided with a sliding clasp arranged to draw
the two sides together into a locked configuration when pulled along the rib and groove
7 and 8.
1. An insulated carrier bag comprising an outer bag of plastic film including integral
handle apertures the outer bag being bonded to an inner bag of plastic film along
top edges thereof below the handle apertures so as to enclose therebetween an insulating
material and further comprising an upstanding flange of plastic film inside the outer
bag along each of the said top edges and bonded to, or integral with, the inner bag,
the flanges being a pair of opposed flanges including a linear resilient closure.
2. A carrier bag according to claim 1 in which the upstanding flanges include a closure
comprising a rib and groove adapted to interlock.
3. A bag according to claim 1 or claim 2 in which the insulating material is a bubble
film type of construction.