Note: Descriptions are shown in the official language in which they were submitted.
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TEAR TAPE
FIELD OF THE INVENTION
This invention relates to a tear tape, to a package when
wrapped with an overwrap material carrying the tear tape and to a method
of wrapping a package.
It has become common practice in recent years to wrap a
package in a transparent overwrap material which is folded around the
package body to provide seams of the overlapped wrapping material
generally along the edges of the package body which are then bonded
together to enclose the package body. Some such packages are sensitive
to moisture loss and in order to maximize shelf life the overwrap material is
bonded in a manner, generally by heat sealing, that provides a moisture
impermeable seal at the seams around the package. In this way the
overwrap material can be effectively moisture impermeable to prevent the
deterioration which can occur from the moisture loss.
It is also highly desirable for customer satisfaction to provide a
tear tape which allows the overwrap material to be torn and therefore
readily removed in a simple tearing action. The tear tape comprises a
narrow tape body which is attached by a bead of adhesive to the inside
surface of the overwrap material so that the tear tape extends around the
package body with an end tab portion of the tear tape exposed through one
seam of the overwrap material to allow that end tab portion to be manually
grasped and pulled. The tear tape body is formed of a material which has
sufficient strength in a longitudinal direction to allow the pulling action to
tear the overwrap material in a tear line following the tear tape thus dividing
the overwrap material into two separate portions which can be readily
removed from the package.
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The adhesive on the outer surface of the tear tape ensures an
adequate bonding effect of the outer surface of the tear tape to the inner
surface of the overwrap material. However it is not in any way possible to
provide an adhesive material on the inside surface of the tear tape since this
would otherwise bond to the package thus reducing the effectiveness of the
tear tape to tear the overwrap material and more importantly tending to tear
away the outer surface of the package itself which is totally unacceptable.
SUMMARY OF THE INVENTION
It is one object of the present invention, therefore to provide an
improved tear tape construction, an improved resultant wrapped package
using the tear tape construction and an improved method of wrapping a
package.
According to the first aspect of the invention there is provided
a wrapped package comprising a package body, an overwrap material
formed of a transparent, tearable plastics material having an inner surface
wrapped around the body to fully enclose the body with an outer surface of
the overwrap material exposed outwardly of the body, the overwrap
material being folded to form overlapping seams of the overwrap material
along the package body, the overwrap material at the overlapping seams
being bonded together to prevent moisture loss through the seams, a tear
tape, adhesive means on an outer surface of the tear tape adhesively
attaching the tear tape to the inner surface of the overwrap material, the
tear tape being wrapped around the package body with an inside surface
thereof in contact with the package body and having an end tab portion of
the tear tape projecting through a seam of the overwrap material to allow
manual grasping of the tear tape, the tear tape having longitudinal strength
sufficient to enable it when pulled to tear the overwrap material to allow
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unwrapping of the package body, the tear tape being formed of a plastics
material dissimilar from the overwrap material such that the plas.ics material
of the tear tape is not heat bondable to the overwrap material and having a
heat sealable coating layer on the inside surface of the plastics material of
the tear tape, which heat sealable coating layer is not bonded to the
package body and is heat bonded to the overwrap material so as to provide
a bonded seal between the inside surface of the end tab portion and the
overwrap material at said seam to prevent moisture loss between the inside
surface of the tear tape and the overwrap material.
According to a second aspect of the invention there is provided
a tear tape for application to an overwrapping sheet material for wrapping a
package body, the tear tape comprising an elongate tape body formed of a
plastics material having a longitudinal strength sufficient to enable it when
pulled to tear the overwrap material to allow unwrapping of the package
body, the tear tape body being formed from polyester and having on one
surface thereof a layer of a material which is non-adhesive, is heat bondable
to polypropylene and is not heat bondable to paper.
According to a third aspect of the invention there is provided
method of wrapping a package comprising providing a package body,
wrapping around the body an overwrap material formed of a transparent,
tearable plastics material so as to define an inner surface wrapped around
the body to fully enclose the body and an outer surface of the overwrap
material exposed outwardly of the body, folding the overwrap material to
form overlapping seams of the overwrap material along the package body,
bonding the overwrap material at the overlapping seams together to
prevent moisture loss through the seams, providing a tear tape having
adhesive means on an outer surface of the tear tape, adhesively attaching
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the tear tape to the inner surface of the overwrap material, wrapping the
tear tape around the package body with an inside surface thereof in contact
with the package body and having an end tab portion of the tear tape
projecting through a seam of the overwrap material to allow manual
grasping of the tear tape, the tear tape having longitudinal strength
sufficient to enable it when pulled to tear the overwrap material to allow
unwrapping of the package body, the tear tape being formed of a plastics
material dissimilar from the overwrap material such that the plastics material
of the tear tape is not heat bondable to the overwrap material and having a
heat sealable coating layer on the inside surface of the plastics material of
the tear tape, which heat sealable coating layer is not bonded to the
package body, and heat bonding the heat sealable coating layer to the
overwrap material so as to provide a bonded seal between the inside
surface of the end tab portion and the overwrap material at said seam to
prevent moisture loss between the inside surface of the tear tape and the
overwrap material.
Generally, therefore, the tear tape which is conventionally
formed of polyester and which is preferably biaxially oriented is
supplemented by the provision of a layer on the inside surface of the tear
tape body which is compatible with the overwrap material to allow a heat
actuated bonding effect in the heat sealing process. This ensures a seal
between the inside surface of the tear tape at the end tab portion and the
adjacent portion of the overwrap material to complete the seal of the
overwrap material around the package to further reduce moisture loss.
Preferably the overwrap material is formed of polypropylene
which may itself have a covering layer of acrylic or maybe doped in order to
improve the heat sealing characteristics.
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The heat sealable coating layer applied to the inner surface only
of the polyester tear tape can itself comprise an acrylic material or a PVDC
material. Preferably the material is of a nature which flows at a temperature
in the range 200 to 300F so that it is readily heat sealable and is
compatible with the material of the overwrap. Such a layer can have a
thickness less than 0.0002 inches (0.005mm) since the material is provided
simply to give the required heat sealing characteristics and has no effect on
the structural strength of the tear tape.
The layer can be applied as a coating for example as a water
based material applied after the formation of the base sheet from which the
tear tapes are slit, or can be coextruded with the base sheet. In the latter
case, the thickness will be generally a little greater.
One embodiment of the invention will now be described in
conjunction with the accompanying drawings in which:
DESCRIPTION OF THE DRAWINGS
Figure 1 is an isometric view of a package according to the
present invention.
Figure 2 is a cross sectional view on an enlarged scale showing
schematically the layers of the packaging material including the package
body, the tear tape and the overwrap material, the cross section being taken
along the lines 2-2 of Figure 1.
Figure 3 is a similar cross sectional view showing the package
body, the tear tape and the overwrap material taken along the lines 3-3 of
Figure 1.
In the drawings like characters of reference indicate
corresponding parts in the different figures.
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DETAILED DESCRIPTION
The package of the present invention is shown in Figures 1, 2
and 3 and is illustrated in one example as a cigarette package including an
outer package body formed of a paper material and indicated at 10. On the
paper material is printed the necessary information including logos 11 and
12. The construction of the folded paper package is conventional and
therefore will not be described in detail herein.
Around the paper package body is wrapped a layer of an
overwrap material 14 which comprises a transparent, tearable plastics film
which is generally but not exclusively of polypropylene which has the
desirable characteristics of moisture impermeability, tearability, clear
transparency and sufficient strength to resist abrasion or impact damage.
The overwrap material is wrapped around the package and folded at fold
lines so as to shape the material to encompass the whole of the package
with seams 14C one of which is visible along one side edge of the package.
The seams are provided by an overlapping of two layers 14A and 14B of the
overwrap material which are heat sealed together by the application of heat
and pressure to provide a complete circumferential seal around the seams so
that the whole of the package is fully enveloped by the moisture
impermeable material.
A tear tape 15 is wrapped around the package between the
package and the overwrap to allow tearing of the overwrap at the line
defined by the tear tape for unwrapping and removal of the overwrap.
The tear tape 15 includes a tape body 16 formed of a suitable
plastics material to provide the required longitudinal strength to effect the
tearing action. Preferably the tear tape body 16 is formed from polyester
which is biaxially oriented which has been found to provide the required
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degree of strength and other characteristics such as the ability to print
indicia on the layer and the ability of the material to be wound into a
cylindrical package of the material. In one example the thickness of the
polyester material may lie in the range 0.00048 to .002 inches and the
width of the tape body will be of the order of 1.6 to 10 mm and more
preferably 2 to 5 mm.
The tape body 16 includes an outer surface 17 and an inner
surface 18. As shown in Figure 3 at the majority of the periphery of the
package, the inside surface 18 lies adjacent or in contact with the package
material 10. The outer surface 17 carries an adhesive layer 19 which acts
to bond the outer surface of the tear tape body to the inner surface of the
overwrap material. Preferably the adhesive layer 19 is of a hot melt type
which is applied to the overwrap film on line with the packaging process so
that it is applied to the overwrap film as the overwrap film is led to the
packaging system and hence remains in the adhesive condition at the time
that the tear tape is brought into contact with the overwrap material. As an
alternative, however, the adhesive material may be of the pressure sensitive
type.
On the outer surface 17 of the tape body is applied a layer of
printed indicia 20 which is applied to the surface 17 prior to the application
of the adhesive 19. The adhesive is sufficiently transparent that the indicia
are visible through the adhesive layer and through the overwrap material as
shown in Figure 1. On the underside 18 of the tape body 16 is provided an
additional layer 22 which is a heat sealable coating layer and forms an
integral part of the tape body and is carried thereby. The additional layer 22
covers the whole of the lower surface 18 but is not applied to the surface
17 of the tape body. The layer 22 is formed from a material which has the
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ability to flow under application of heat to a temperature in the range 200
to 300F. The layer may be formed of an acrylic material, PVDC material
or some other suitable bondable layer either as a coextrusion with the tape
body or as a subsequently applied coating. The thickness of the layer is
very thin since it provides no structural strength to the tape but simply is
provided in order to cooperate with the overwrap material in providing a
seal.
The layer 22 is therefore non-adhesive so that it does not in
any way adhere to the paper stock 10 in the area where it is an engagement
with that paper stock so that there is no bonding between the tear tape and
the paper stock which could cause tearing.
However the layer is arranged to be compatible with the
overwrap material so that it engages the layer 14B in the seam area and is
heat sealed to the layer 14B by the conventional heat sealing process which
seals the layer 14A to the layer 14B of the overwrap material. Thus the
heat seal extends around the full periphery around the seam without any
break in the seal at the underside of the tear tape.
Thus as shown in Figure 1, the conventional end pull tab 25 of
the tear tape projects through the seam between the layers 14A and 14B to
be exposed on the outside of the overwrap to be grasped and pulled in the
tearing action.
Since various modifications can be made in my invention as
herein above described, and many apparently widely different embodiments
of same made within the spirit and scope of the claims without departing
from such spirit and scope, it is intended that all matter contained in the
accompanying specification shall be interpreted as illustrative only and not
in a limiting sense.
