Note: Descriptions are shown in the official language in which they were submitted.
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EASY-OPEN HANDLE BAG
FOR MEDIUM TO HEAVY DUTY APPLICATIONS
BACKGROUND OF THE INVENTION
[0001] The present invention generally relates to thermoplastic handle bags
suitable for
storing and transporting medium to heavy loads, e.g., frozen foods such as
chickens, turkeys,
and the like comprising an easy-open feature, and more particularly, to
thermoplastic handle
bags having an easy-open feature adapted for the removal of large or bulky
medium to heavy
loads contained therein.
[0002] Thermoplastic bags having a handle opening and/or an easy-open feature
which
support heavy granulated items such as salt pellets, pet food, fertilizer,
etc. are known in the
art. U.S. Patent No. 6,231,232 to Warr is directed to synthetic bags primarily
for granulated
contents which are capable of carrying loads of from 10 to SO pounds and which
include a
hand-insertion slit below the top seal of the bag that may serve as a handle.
U.S. Patent Nos.
5,482,376 and 5,601,369, both to Moseley et al. also disclose bags adapted to
hold pourable
contents from 20 to 150 pounds. These bags include a handle which is either
attached or
formed from the bag and further disclose a curved line of perforations in the
comer portion of
the bag which permits easy opening of the bag. U.S. Patent Nos. 5,482,376 and
5,601,369
both to Warn further disclose thermoplastic bags designed for heavy-duty
applications which
include a die-cut handle opening similar to that described in U.S. Patent No.
6,231,232 and an
easy-open feature which comprises a line of perforations which extends from
the top edge to
the side edge at the comer of the bag. While these bags are capable of
carrying medium to
heavy load and are easy to open, they are not suitable for large or bulky
items contained therein
which require a different means of removal from the package.
[0003] It is also known in the art that flexible bags may include both a
handle and an opening
zone in the side of the package which facilitates in the removal of bulky
items contained
therein. U.S. Patent Nos. 4,966,286 to Muckenfuhs; 5,036,978 to Frank et al.
and 5,054,619
to Muckenfuhs describe thermoplastic packages which are suitable for storing
and transporting
compressed flexible articles, such as disposable absorbent products, e.g.,
diapers, bandages,
sanitary napkins and the like. These packages have a carrying handle and an
easy open feature
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which consists of one or more arcuate lines of weakness in a side panel or
gusset of the bag.
While these bags allow for easy removal of relatively bulky contents, they
will neither
separately support medium to heavy loads nor will the perforated tear lines of
the easy-open
feature resist tearing or bursting during transportation or storage of medium
to heavy loads.
SLJMMA~tY OF THE INVENTION
[0004] The present invention provides flexible bags that resists tearing or
bursting during the
storage and transportation of medium to heavy duty loads which may range in
weight from
about five pounds to about fifty pounds or more. The present invention also
provides flexible
bags formed from thermoplastic films which include a handle opening and an
easy-open
feature. The present invention further provides flexible bags suitable for
supporting medium
to heavy duty loads which include an easy-open feature suitable for removing
large or bulky
items contained therein.
[0005] Accordingly, one aspect of the present invention is directed to
flexible bags for
medium to heavy duty packaging applications which have a body formed from a
thermoplastic
film having an inner surface and an outer surface relative to the bag.
Preferably, the flexible
bags include a body formed from a thermoplastic film having an unrestrained
linear thermal
shrinkage in both the machine direction and the transverse direction of
between 0-10 % at 85°
C. as measured in accordance with ASTM D-2732-96, which is hereby
incorporated, in its
entirety, by reference thereto. Preferably, the thermoplastic filin has a
minimum tensile
strength at break in the machine direction of at least 3000 psi (2x 10' N/m2)
as measure at a rate
of 12 inch/min. (30.5 cm/min.) in accordance with ASTM D-882, which is hereby
incorporated, in its entirety, by reference thereto. Preferably, the
thermoplastic film has a
maximum elongation at break in the machine direction of between 0-150 % as
measure at a
rate of 12 inch/min. (30.5 cm/min.) in accordance with ASTM D-882, which is
hereby
incorporated, in its entirety, by reference thereto. Preferably, the film has
a total thickness of
from about 2.0 to 7.0 mils (0.005 to 0.018 cm). Although the thermoplastic
film may be a
monolayer film or a multilayer film, preferably the film is a multilayer film.
Preferably, the
film is a multilayer film comprising at least a first polymer layer, a second
polymer layer, and a
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third polymer layer. The first polymer layer of the thermoplastic multilayer
film comprises a
material selected from the group consisting of polyester, polyamide, polyolefm
or blends
thereof, preferably, a material selected from the group consisting of
polyester terephthalate,
polyamide, polypropylene or blends thereof, and most preferably, either a
biaxially-oriented
polyester terephthalate or a biaxially-oriented polyamide. The second polymer
layer of the
thermoplastic multilayer film comprises an adhesive material. The third
polymer layer of the
thermoplastic multilayer film comprises a sealant material. Preferably, the
second polymer
layer is directly adhered to the first and third polymer layer. For certain
packaging
applications, it may be beneficial to include the three-layer thermoplastic
film as a substructure
in a larger multilayer flexible film in forming the body of a bag. In such a
configuration, the
larger multilayer film incorporating three-layer structure as a substructure
may advantageously
possess properties and benefits resulting from the three-layer structure as
discussed herein, but
may also possess additional properties and benefits arising from the
additional layers. Larger
multilayer filin structures which incorporate three-layer structure as a
substructure may have at
least one additional layer adhered to this substructure by various methods
known to those
skilled in the art which include thermal lamination, adhesive lamination,
coextrusion coating,
coextrusion lamination.
(0006) The present invention is also directed to bags which include a first
panel and a second
panel where each of the panels have a perimeter which includes a first
peripheral side edge and
an opposing second peripheral side edge, connected by a peripheral top edge
and an opposing
peripheral bottom edge. The body also includes a plurality of seals which
joins the first panel
to the second panel. In one embodiment of the present invention, the plurality
of seals include
a first side seal, a first top seal and an opposing bottom seal. The first
side seal, first top seal
and opposing bottom seal can be connected together to form a seal perimeter
between the first
and second panels. Alternatively, the plurality of seals may further include a
first side seal and
an opposing second side seal, a first top seal and an opposing bottom seal. In
this regard, the
first side seal and opposing second side seal, the first top seal and opposing
bottom seal can be
connected together to form a seal perimeter. In another embodiment, the
plurality of seals may
still fiuther include a first side seal and an opposing second side seal, a
first top seal, a second
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top seal and an opposing bottom seal. Preferably, the second top seal is
parallel with the first
top seal and positioned below the handle opening of the bag extending
transversely across the
bag from the first peripheral side edge to the second peripheral side edge. In
this particular
embodiment, the first side seal and opposing second side seal, the second top
seal and
opposing bottom seal can be connected together to form a seal perimeter. The
body of the
bags are provided with a receptacle cavity which is formed between the first
and second panels
and defined by the seal perimeter. While the flexible bags of the present
invention need not
necessarily include side gussets, for some applications it may be beneficial
to include at least
one of : a first side gusset and a second side gusset, a bottom gusset, or a
first side gusset, a
second side gusset and a bottom gusset.
[0007] As a second aspect, the present invention is directed to flexible bags
for medium to
heavy duty packaging applications which include an integral handle opening.
The integral
handle opening is disposed in a pre-determined area below the peripheral top
edge and extends
transversely across the bag from a first peripheral side edge to a second
peripheral side edge.
The integral handle opening may be formed in the first and second panels of
the body of the
bag as either a hole, slit, cut and the like. Preferably, the pre-determined
area in the first panel
and the second panel is a reinforced portion of the body of the bag.
[0008] As a third aspect, the present invention is directed to flexible bags
for medium to .
heavy duty packaging applications having an easy-open feature adapted such
that large and/or
bulky items may be easily removed from the receptacle cavity of the bag.
Examples of large or
bulky items include, but are not limited to, fresh or frozen meat and poultry,
such as turkey,
chicken, duck and the like. The easy-open feature extends longitudinally from
the peripheral
top edge to the peripheral bottom edge in either the first panel or the second
panel and is
positioned adjacent to either the first peripheral side edge or the second
peripheral side edge of
the body of the bag.
(0009] In one embodiment of the invention, the easy-open feature may include
at least one
line of structural weakness in either the inner surface or the outer surface
of the thermoplastic
filin. Preferably, the. at least one line of structural weakness further
includes a tear-initiation
feature. A tear-initiation feature may be formed as a cut, notch or surface-
roughening area and
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the like, in the external surface of film positioned above the at least one
line of structural
weakness. In this regard, the bag can be easily opened by a relatively weak
manual force at the
tear-initiation feature and in combination with the at least one line of
structural weakness
obviating the need to cut the bag with a knife, scissors or any other sharp
implement.
[0010] Alternatively, the easy-open feature may be provided as a reclosable
fastener attached
to the inner surface of the thermoplastic film forming the body of the bag.
Suitable reclosable
fastener, in general, are known and are taught, for example, in
U. S. Patent Nos. 5,063,644; 5,301,394; 5,442,837; 5,964,532; 6,409,384;
6,439,770;
6,524,002; 6,527,444; 6,609,827; 6,616,333; 6,632,021; 6,663,283; 6,666,580;
6,679,027; and
U.S. Patent Application Nos. 2002/0097923; and 2002/0196987, each of which is
incorporated
by reference herein.
[0011] Preferably, the reclosable fastener comprises a first interlocking
member and a second
interlocking member. Preferably, the first and second interlocking members
each have an
attachment flange for securing each member to the inner surface of the
thermoplastic film
forming the body of the bag. Preferably, the reclosable fastener further
comprises a slider
device which facilitates the manual operation of the fastener by engaging and
dis-engaging the
first interlocking member with the second interlocking member.
[0012] In another embodiment, the easy-open feature may include a combination
of both the
at least one line of structural weakness in either the inner surface or the
outer surface of the
thermoplastic filin and the reclosable fastener attached to the inner surface
of the thermoplastic
film.
[0013] The present invention is also directed to flexible bags for medium to
heavy duty
packaging applications which further comprises at least one removable
thermoplastic inner
package disposed within and separate from the bag. Preferably, the at least
one removable
thermoplastic inner package comprises a freezer storage package.
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BRIEF DESCRIPTION OF THE DRAWll~TGS
[0014] FIG. 1 is a partially schematic, front plan view of one embodiment of a
flexible bag
according to the present invention showing one example of an easy-open
feature.
[0015] FIG. 2 is a partially schematic, front plan view of an alternative
embodiment of a
flexible bag according to the present invention showing another example of an
easy-open
feature.
[0016] FIG. 3 is a partially schematic, front plan view of still another
embodiment of a
flexible bag according to the present invention having an easy-open feature
similar to that
depicted in FIG.1.
[0017] FIG. 4 is a cross-sectional view of a thermoplastic film which forms
the body of the
flexible bags according to the present invention.
DETAILED DESCRIPTION OF THE INVENTION
[0018] As used herein, the term "multilayer" refers to a plurality of layers
in a single film
structure generally in the form of a sheet or web which can be made from a
polymer material
or a non-polymer material bonded together by any conventional means known in
the art, i.e.,
coextrusion, extrusion coating, and lamination, vacuum vapor deposition
coating, solvent
coating, emulsion coating, or suspension coating or combination of one or more
thereof. The
multilayer film of the present invention may include as many layers as
desired, preferably, at
least three polymer layers.
(0019] As used herein, the phrase "thermoplastic" refers to a polymer or
polymer mixture that
softens when exposed to heat and returns to its original condition when cooled
to room
temperature. In general, thermoplastic materials include, but are not limited
too, synthetic
polymers such as polyamides, polyolefins, polyalkyl acrylates, polyesters,
ethylene/vinyl
alcohol copolymers, and the like. Thermoplastic materials may also include any
synthetic
polymer that are cross-linked by either radiation or chemical reaction during
a manufacturing
process operation.
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[0020] As used herein, the term "polymer" refers to the product of a
polymerization reaction,
and is inclusive of homopolymers, copolymers, terpolymers, etc. In general,
the layers of a
film can consist essentially of a single polymer, or can have still additional
polymers together
therewith, i. e., blended therewith.
[0021] As used herein, the term "copolymer" refers to polymers formed by the
polymerization of reaction of at least two different monomers. For example,
the term
"copolymer" includes the co-polymerization reaction product of ethylene and an
a-olefin, such
as 1-hexene. The term "copolymer" is also inclusive of, for example, the co-
polymerization of
a mixture of ethylene, propylene, 1-propene, 1-butene, 1-hexene, and 1-octene.
As used
herein, a copolymer identified in terms of a plurality of monomers, e.g.,
"propylene/ethylene
copolymer", refers to a copolymer in which either monomer may copolymerize in
a higher
weight or molar percent than the other monomer or monomers. However, the first
listed
monomer preferably polymerizes in a higher weight percent than the second
listed monomer.
(0022] As used herein, the term "extrusion" refers to the process of forming
continuous
shapes by forcing a molten polymeric material through a die, followed by
cooling.
[0023] As used herein, the term "coextrusion" refers to the process by which
the outputs of
tow or more extruders are brought smoothly together in a feed block, to form a
multilayer
molten mixture that is fed to a die to produce a layered extrudate.
Coextrusion can be
employed in film blowing, sheet and flat film extrusion, blow molding, and
extrusion coating.
[0024] As used herein, the term "biaxially-oriented"refers to a polymer web
which forms a
film structure in which the web has been elongated in two directions at
elevated temperatures
followed by being "set" in the elongated configuration by cooling the material
while
substantially retaining the elongated dimensions. This combination of
elongation at elevated
temperature followed by cooling causes an alignment of the polymer chains to a
more parallel
configuration, thereby improving the mechanical properties of the polymer web.
Upon
subsequently heating of certain unrestrained, unannealed, biaxially-oriented
sheet of polymer
to its orientation temperature, heat-shrinkage may be produced. Following
orientation, the
biaxially-oriented polymer web is preferably cooled and then heated to an
elevated
temperature, most preferably to an elevated temperature which is above the
glass transition
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temperature and below the crystalline melting point of the polymer. This
reheating step, which
may be referred to as annealing or heat setting, is performed in order to
provide a polymer web
of uniform flat width. In accordance with the present invention, the biaxially-
oriented polymer
web may be used to form a film layer is heated to an elevated temperature in
order to provide a
packaging film with an unrestrained linear thermal shrinkage in the machine
direction of
between 0-10 % at 85° C. as measured in accordance with ASTM D-2732-96
test method,
which is incorporated herein by reference.
[0025] As used herein, the terms "joins" or "joining" are used in its broad
sense to mean
either two formerly separate sheets connected together, or integrally formed
by, for example,
folding over a film or laminate to define an edge.
[0026] As used herein, the phrase "machine direction" refers to a direction
"along the length"
of the film, i. e., in the longitudinal direction the film is formed during
extrusion. In contrast,
the "transverse direction" refers to the direction across the film or
perpendicular to the
machine direction.
[0027] As used herein, terminology employing a "/" with respect to the
chemical identity of a
copolymer (e.g., polyvinylidene chloride/methyl acrylate copolymer),
identifies the
comonomers which are copolymerized to produce the copolymer.
[0028) As used herein, the term "polyester" refers to homopolymers or
copolymers having an
ester linkage between monomer units which may be formed, for example, by
condensation
polymerization reactions between a dicarboxylic acid and a glycol. The
dicarboxylic acid may
be linear or aliphatic, i. e., oxalic acid, malonic acid, succinic acid,
gIutaric acid, adipic acid,
pimelic acid, suberic acid, azelaic acid, sebacic acid, and the like; or may
be aromatic or alkyl
substituted aromatic, i.e., various isomers of phthalic acid, such as
paraphthalic acid (or
terephthalic acid), isophthalic acid and naphthalic acid. Specific examples of
alkyl substituted
aromatic acids include the various isomers of dimethylphthalic acid, such as
dimethylisophthalic acid, dimethylorthophthalic acid, dimethylterephthalic
acid, the various
isomers of diethylphthalic acid, such as diethylisophthalic acid,
diethylorthophthalic acid, the
various isomers of dimethylnaphthalic acid, such as 2,6-dimethylnaphthalic
acid and 2,5-
dimethylnaphthalic acid, and the various isomers of diethylnaphthalic acid.
The glycols may
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be straight-chained or branched. Specific examples include ethylene glycol,
propylene glycol,
trimethylene glycol, 1,4-butane diol, neopentyl glycol and the like. In one
example a preferred
embodiment of this invention, the first layer comprises polyethylene
terephthalate copolymer
and most preferable, biaxially-oriented polyethylene terephthalate copolymer.
[0029] As used herein, the term "adhesive" refers to a polymer material
serving a primary
purpose or fimction of adhering two surfaces to one another. In the present
invention, the
adhesive may adhere one filin layer surface to another film layer surface or
one area of a film
layer surface to another area of the same filin layer surface. The adhesive
may comprise any
polymer, copolymer or blend of polymers having a polar group thereon, or any
other polymer,
homopolymer, copolymer or blend of polymers including modified and unmodified
polymers,
e.g., grafted copolymers, which provide sufficient interlayer adhesion to
adjacent layers
comprising otherwise nonadhering polymers. Adhesive compositions of the
present invention
may include, but are not limited to, modified and unmodified polyolefins,
preferably
polyethylene, such as for example, low-density polyethylene, linear low-
density polyethylene,
medium-density polyethylene, and modified and unmodified copolymers of
ethylene with one
or more alpha-olefins (a-olefins) such as butene-1, hexene-1, octene-1, or the
like as a
comonomer.
[0030] As used herein, the term "polyolefin" refers to homopolymers,
copolymers, including
e.g. bipolymers, terpolymers, etc., having a methylene linkage between monomer
units which
may be formed by any method known to those skill in the art. Suitable examples
of
polyolefins include polyethylene, low density polyethylene, linear low density
polyethylene,
very low density polyethylene, ultra low density polyethylene, medium density
polyethylene,
high density polyethylene, polyethylenes comprising ethylene/a-olefin which
are copolymers
of ethylene with one or more alpha-olefins (a-olefins) such as butene-1,
hexene-1, octene-1, or
the like as a comonomer, linear low density polyethylene, very low density
polyethylene, ultra
low density polyethylene, ethylene/propylene copolymers, polypropylene,
propylene/ethylene
copolymer, polyisoprene, polybutylene, polybutene, poly 3-methylbutene-l, poly-
4-
methylpentene-1, ionomers and the like.
[0031j As used herein, the phrase "ethylene/a-olefin" refers to a modified or
unmodified
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copolymer produced by the co-polymerization of ethylene and any one or more a-
olefin. The
a-olefin in the present invention may have between 3-20 pendant carbon atoms.
The co-
polymerization of ethylene and an a-olefin may be produced by heterogeneous
catalysis, i. e.,
co-polymerization reactions with Ziegler-Natta catalysis systems, for example,
metal halides
activated by an organometallic catalyst, i.e., titanium chloride, optionally
containing
magnesium chloride, complexed to trialkyl aluminum and may be found in patents
such as
U.S. Patent No. 4,302,565 to Goeke, et al. and U.S. Patent No. 4,302,566 to
Karol, et al., both
of which are hereby incorporated, in their entireties, by reference thereto.
[0032] As used herein, the term "modified" refers to a chemical derivative,
e.g., one having
any form of anhydride functionality, such as anhydride of malefic acid,
crotonic acid, citraconic
acid, itaconic acid, fumaric acid, etc., whether grafted onto a polymer,
copolymerized with a
polymer, or blended with one or more polymers, and is also inclusive of
derivatives of such
functionalities, such as acids, esters, and metal salts derived therefrom.
[0033] As used herein, the term "polyamide" refers to homopolymers,
copolymers, or
terpolymers having an amide linkage between monomer units which may be formed
by any
method known to those skill in the art. Useful polyamide homopolymers include
nylon 6
(polycaprolactarn), nylon 11 (polyundecanolactam), nylon I2
(polylauryllactam), and the like.
Other useful polyamide homopolymers also include nylon 4,2
(polytetrarnethylene
ethylenediamide), nylon 4,6 (polytetramethylene adipamide), nylon 6,6
(polyhexamethylene
adipamide), nylon 6,9 (polyhexamethylene azelamide), nylon 6,10
(polyhexamethylene
sebacamide), nylon 6,12 (polyhexamethylene dodecanediamide), nylon 7,7
(polyheptamethylene pimelamide), nylon 8,8 (polyoctamethylene suberaunide),
nylon 9,9
(polynonamethylene azelamide), nylon 10,9 (polydecamethylene a.zelamide),
nylon 12,12
(polydodecamethylene dodecanediamide), and the like. Useful polyamide
copolymers include
nylon 6,6/6 copolymer (polyhexamethylene adipamide/caprolactam copolymer),
nylon 6/6,6
copolymer (polycaprolactam/hexamethylene adipamide copolymer), nylon 6,2/6,2
copolymer
(polyhexamethylene ethylenediamide/hexamethylene ethylenediamide copolymer),
nylon
6,6/6,9/6 copolymer (polyhexamethylene adipamide/hexamethylene
azelaiamide/caprolactam
copolymer), as well as other nylons which are not particularly delineated
here.
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[0034] As used herein, the term "sealant" refers to a layer which is heat
sealable to itself, i.e.,
be capable of fusion bonding by conventional indirect heating means which
generate sufficient
heat on at least one film contact surface for conduction to the contiguous
film contact surface
and formation of a bond interface therebetween without loss of the film
integrity.
Advantageously, the bond interface must be sufficiently thermally stable to
prevent gas or
liquid leakage therethrough. Suitable examples of sealants for the present
invention include,
but are not limited to, polyolefins, including polyethylenes, polypropylenes,
polybutylenes,
ionomers, ethylene/a-olefin copolymers and blends thereof.
[0035] As used herein, the term "surface-roughened" refers to dimples,
indentations,
scratches, bores, holes, perforations, and the like, on an external surface of
a film. It will be
recognized by those skilled in the art, that the dimples, indentations,
scratches, bores, holes,
perforations, and the like may have a random or regular repeating arrangement.
Generally, a
predetermined portion (less than the entire area) of a surface of the film is
treated in order to
provide a surface-roughened portion. The surface-roughened portion may be
formed by
mechanical means, e.g., subjecting the external surface of the film layer to
knurling by a roller
formed with a plurality of circumferentially extending projections as
described, for example, in
U.S. Patent Nos. 4,543,279 and 4,778,058, which are incorporated herein by
reference.
Alternatively, non-mechanical methods may be used which include corona
discharge, plasma
discharge, ultrasonic wave, and optical ablation.
[0036] The present invention now will be described more fully hereinafter with
reference to
the accompanying drawings, in which preferred embodiments of the invention are
shown.
This invention may, however, be embodied in many different forms and should
not be
construed as limited to the embodiments set forth herein; rather, these
embodiments are
provided so that this disclosure will be thorough and complete and will fully
convey the scope
of the invention to those skilled in the art. Like numbers refer to like
elements throughout.
[0037] Referring now to FIG. 1, bag 10 represents one example of a flexible
bag according to
the present invention having one embodiment of an easy-open feature. As shown,
bag 10 is
depicted as comprising a body 11 which is formed from a thermoplastic film 12
having an
inner surface 13a (See FIG. 4) and an outer surface 13b (See FIG. 4) relative
to the bag. It
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should be appreciated by a person of ordinary skill in art that body 11 may
comprise one or
more monolayer or multilayer thermoplastic films suitable for use with medium
to heavy duty
packaging applications. The body 11 of bag 10 comprises a first panel 14a and
a second panel
14b (See FIG. 2) such that the panels, 14a and 14b, each have a perimeter 15
and 15' (See FIG.
2). Perimeter 15 includes a first peripheral side edge 16a and an opposing
second peripheral
side edge 16b connected by a peripheral top edge 16c and an opposing
peripheral bottom edge
16d. Body 11 also includes a plurality of seals 17 comprising at least a first
side seal 17a, a
first top seal 17b and an opposing bottom seal 17c, all which join first panel
14a to second
panel 14b. It should be appreciated by a person of ordinary skill in art that
the body 11 of bag
may be integrally formed by folding a thermoplastic film 12 over onto itself
and sealing
first panel 14a to second panel 14b (See FIG. 2) thus creating a seal
perimeter 18 which is
comprised of first side seal 17a, first top seal 17b and opposing bottom seal
17c.
Alternatively, body 11 may be fabricated from more than one thermoplastic
films which may
include thermoplastic filin 12 by sealing the four peripheral edges of first
panel 14a and 14b
(See FIG. 2) together thereby providing a seal perimeter 18 having a first
side seal 17a, a
second side seal 17d (See FIG. Z), a first top seal 17b and an opposing bottom
seal 17c.
[0038] Body 11 further comprises an inner receptacle cavity 19 (not shown)
which is formed
between first panel 14a and opposing second panel 14b and defined by a seal
perimeter 18,
and an integral handle opening 20 which extends transversely across the bag 10
from the first
peripheral side edges 16a to the second side edges 16b. Integral handle
opening 20 may be
fabricated, for example, by slitting or die cutting into first panel 14a and
second panel 14b at
the same time such that the slit or cut in first panel 14a is in registration
with the slit or cut in
second panel 14b. Body 11 also includes an easy-open feature 21 which extends
longitudinally from the first top seal 17b to opposing bottom seal 17c and is
disposed adjacent
to peripheral side edge 16a of the first panel 14a. Easy-open feature 21, by
way of example, is
depicted as being at least one line of structural weakness 21 a in the first
panel 14a and may be
formed in either the inner surface 13a (See FIG. 4) or the outer surface 13b
(See FIG. 4) of
thermoplastic film 12. Alternatively, the at one line of structural weakness
21 a may be formed
in second panel 14b (see FIG. 2) in either inner surface 13a (See FIG. 4) or
outer surfacel3b
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(See FIG. 4) of thermoplastic film 12.
[0039] Formation of the at least one line of structural weakness 21 a may be
accomplished by
methods disclosed in U.S. Patent Nos. 3,626,143; 3,909,582; 4,778,058;
4,834,245; 5,001,325;
5,613,779; 5,630,308; and 6,427,420, which are hereby incorporated by
reference. These
methods include e.g., forming grooves, scores, scratches, cuts, slits or
surface roughening e.g.,
with a laser, by corona or plasma discharge, by contact with a rough surface
roller or
roughened surface such as sand paper, emery paper, or by cutting devices or
blades. For
example, the at least one line of structural weakness may be provided by any
of the methods
disclosed in the aforementioned documents, such as using a cutting device to
form the at least
one line of structural weakness in a first moving web or layer followed by
lamination of the
first moving web or layer to a second moving web or layer with or without tear-
initiation
features or the like. It will be appreciated that at least one line of
structural wealrnesses 21a
may be provided in a variety of shapes including curves or sinusoidal and may
also be
provided either continuously or intermittently along the inner surface 13a
(See FIG. 4) or the
outer surface 13b (See FIG. 4) of thermoplastic filin 12 of first panel 14a or
second panel 14b.
While at least one line of structural weaknesses 21 a may be provided having a
depth of the
entire thickness of thermoplastic film 12, e.g., by intermittent perforations
or slits, it is
preferred that the at least one line of structural weaknesses has a depth of
less than the entire
thickness of the panel that it is formed on. It will be appreciated that the
at least one line of
structural weakness may be provided in any length along either panel between
from first top
seal 17b to opposing bottom seal 17c.
[0040] Referring now to FIG. 2, bag 20 represents another example of an
embodiment of the
present invention. Bag 20 comprises a body 11 of a first panel 14a (See FIG.
1) and second
panel 14b such that second panel 14b has a perimeter 15' which includes a
first peripheral side
edge lfia' and an opposing second peripheral side edge 16b', connected by a
peripheral top
edge 16c' and an opposing bottom edge 16d'. Body 11 includes a plurality of
seals 17 which
joins first panel 14a to second panel 14b and comprises a first side seal 17a
and a second side
seal 17d, a first top seal 17b and a second top seal 17e, and a bottom seal
17c. In this
particular example, the seal perimeter 18 which defines receptacle cavity 19
(not shown)
13
CA 02506953 2005-05-10
consists of first side seal 17a and second side seal 17d, second top seal 17e
and bottom seal
17c. Body 11 also includes integral handle opening 20 that is formed in a
reinforced portion
27a (See FIG. 3) of the first panel 14a and in a reinforced portion the second
panel 27b of
second panel 14b. It should be appreciated by a person of ordinary skill in
art that the
reinforced portions 27a (See FIG. 3) and 27b may be fabricated from a patch of
filin such as
thermoplastic film 12 which is adhered to the portion overlaying and
surrounding handle
opening 20. The film patch is typically applied before the handle opening 20
is formed and
may be secured to first and second panels, 14a and 14b by an adhesive or heat-
fusing process.
Body 11 of bag 20 also comprises a reclosable fastener 21b as the easy-opening
feature
2lwhich is positioned adjacent to first side seal 17a and extends
longitudinally from first top
seal 17b to opposing bottom seal 17c. Reclosable fastener 21b, may include,
but is not limited
to, a reclosable fastener having interlocking members, preferably,
interlocking members and a
slider device 26. Suitable reclosable fasteners, in general, are known and are
taught, for
example, in U.S. Patent Nos. 5,063,644; 5,301,394; 5;442,837; 5,964,532;
6,409,384;
6,439,770; 6,524,002; 6,527,444; 6,609,827; 6,616,333; 6,632,021; 6,663,283;
6,666,580;
6,679,027; and U.S. Patent Application Nos. 2002/0097923; and 2002/0196987,
each of which
is incorporated by reference herein. It will be noted that the reclosable
fastener 21b is not
limited to any particular number of interlocking members and/or slider device
structure. It will
be appreciated that the reclosable fastener 21 b may be chosen which does not
include a slider
device 26 and/or interlocking members.
[0041] Turning now to FIG. 3, bag 30 is still another embodiment of flexible
bags for
medium to heavy duty packaging applications according to the present
invention. Bag 30 is
depicted having a body 11 comprising first panel 14a and second panel 14b (See
FIG. 2), and a
plurality of seals which includes a first top seal 17b, a second top seal 17e
and an opposing
bottom seal 17c, a first side seal 17a and opposing second side seal 17d. The
easy-open
feature 21 of body 11 of bag 30 comprises at least one line of structural
weakness that includes
a tear-initiation feature 23. Tear-initiation feature 23 is provided to
further facilitate the
opening of the package by obviating the need to cut bag 30 at the peripheral
side of the easy-
open feature 21. In this regard, tear-initiation feature 23 may be formed as a
cut, slit, notch,
14
CA 02506953 2005-05-10
score or surface-roughened area in thermoplastic film 12 at a peripheral side
edge which
affords easy opening of bag 30 by a relatively weak manual force. In this way,
a tear begins at
tear-initiation feature 23 and then propagates in the direction of the at
least one line of
structural weakness 21 a.
[0042) FIG. 4 represents an across-sectional view of one embodiment of a
thermoplastic film
suitable for forming a bag according to the present invention. Thermoplastic
film 12 is
depicted as a multilayer thermoplastic film having an inner surface 13a and an
outer surface
13b relative to the bag and comprising at least three layers of a first
polymer layer 12a, a
second polymer layer 12b, and a third polymer layer 12c, such that second
polymer layer 12b
is positioned between first polymer layer 12a and third polymer layer 12c.
Preferably, first
polymer layer 12a may include a material selected from the group consisting of
polyester,
polyamide, polyolefin or blends thereof, more preferably, polyester
terephthalate, polyamide,
polypropylene or blends thereof, and most preferably, biaxially-oriented
polyester terephthalate
or biaxially-oriented polyamide. Preferably, first polymer layer 12a comprises
a biaxially-
oriented polyester terephthalate having a thickness of 0.48 mils (1.22 cm), a
ultimate tensile
strength in the machine direction of 27000 psi, an elongation at break in the
machine direction
of 110 %, a modulus of 550 kpsi. It will be appreciated that first polymer
layer 12a may also
be treated on at least one surface with an anchor coating to improve the
adhesion to an adjacent
layer. An example of a commercially available biaxially-oriented polyester
terephthalate is
sold under the trademark Mylar ~ LBT which is supplied by E.I. de Pont de
Nemours and
Company, Wilmington, Delaware, U.S.A. Preferably, second polymer layer 12b
comprises an
adhesive material. Preferably, polymer layer 12b is a low density polyethylene
having a melt
index of 1.9, a density of 0.922 and a melting point of 110° C., such
as that sold under the
trademark Escorene~ LD-134 and available from ExxonMobil Chemical Company of
Houston, TX, U.S.A. Preferably, polymer layer 12c comprises a sealant material
such as low
density polyethylene. An example of a suitable low density polyethylene having
melt index of
4.1, a density of 0.923, and a melting point of 112° C., such as that
sold under the trademark
Escorene~ LD-201 and available from ExxonMobil Chemical Company of Houston,
TX,
U.S.A. It should be appreciated by a person of ordinary skill in the art that
one or more of the
CA 02506953 2005-05-10
polymer layers described hereinabove may also, if desired, include well known
additives such
as processing aids, slip agents, anti-blocking agents and pigments, printed
indicia and mixtures
thereof.
[0043] Thermoplastic film 12 has an unrestrained linear thermal shrinkage in
both the
machine direction and the transverse direction of between 0-10 % at 85°
C. as measured in
accordance with ASTM D-2732-96, a minimum tensile strength at break in the
machine
direction of at least 3000 psi (2 x 10' N/m2) as measured at a rate of 12
inch/min. (30.5
cm/min.) in accordance with ASTM D-882, and a maximum elongation at break in
the
machine direction of between 0-150 % as measured at a rate of 12 inch/min.
(30.5 cm/min.) in
accordance with ASTM D-882. Preferably, thermoplastic filin 12 has a total
thickness of
between 2.0-7.0 mils (0.005-0.018 cm).
[0044] Unless otherwise noted, the physical properties and performance
characteristics
reported herein were measured by test procedures similar to the following
methods.
Density ASTM D-1505
Melting Point ASTM D-3418
Melt Index ASTM D-1238
Percent Elongation at Break ASTM D-882
Tensile strength at Break ASTM D-882
Modulus ASTM D-882
Unrestrained Linear Thermal ASTM D-2732-96
Shrinkage
[0045] Many modifications and other embodiments of the invention will come to
mind to one
skilled in the art to which this invention pertains having the benefit of the
teachings presented
in the foregoing descriptions and the associated drawings. Therefore, it is to
be understood
that the invention is not to be limited to the specific embodiments disclosed
and that
modifications and other embodiments are intended to be included within the
scope of the
appended claims. Although specific terms are employed herein, they are used in
a generic and
descriptive sense only and not for purposes of limitation.
16
