U.S. patent application number 10/700900 was filed with the patent office on 2004-05-13 for packaging bag with zipper.
This patent application is currently assigned to DAIWA GRAVURE CO. LTD.. Invention is credited to Shibata, Yukihiko.
Application Number | 20040091185 10/700900 |
Document ID | / |
Family ID | 32105469 |
Filed Date | 2004-05-13 |
United States Patent
Application |
20040091185 |
Kind Code |
A1 |
Shibata, Yukihiko |
May 13, 2004 |
Packaging bag with zipper
Abstract
A packaging bag with zipper is provided, which enables easy
identification whether or not the bag has been opened. For this
purpose, in the packaging bag with zipper, the lower end portion of
a male zipper tape and the lower end portion of a female zipper
tape are bonded to the inner faces of respective front side and
rear side sheet sections, or vice versa, along the opening end of
the bag. The opening end comes at the top when the bag is in an
upright state. The respective zipper tapes are bonded together at a
position below the engaging section of the zipper tapes with heat
sealing strength of a degree that allows the zipper tapes to be
manual peeling apart, in such a manner that they may be manually
peeled apart by an interface peeling action, an interlayer peeling
action, or a cohesive peeling action.
Inventors: |
Shibata, Yukihiko;
(Nagoya-shi, JP) |
Correspondence
Address: |
Christopher J. Fildes
Suite 2
20916 Mack Avenue
Grosse Pointe Woods
MI
48236
US
|
Assignee: |
DAIWA GRAVURE CO. LTD.
|
Family ID: |
32105469 |
Appl. No.: |
10/700900 |
Filed: |
November 4, 2003 |
Current U.S.
Class: |
383/210 ;
383/61.2 |
Current CPC
Class: |
B65D 33/2508
20130101 |
Class at
Publication: |
383/210 ;
383/061.2 |
International
Class: |
B65D 033/00 |
Foreign Application Data
Date |
Code |
Application Number |
Nov 7, 2002 |
JP |
2002-323229 |
Claims
What is claimed is:
1. A packaging bag with zipper, in which a lower end portion of a
male zipper tape and a lower end portion of a female zipper tape
are bonded to inner faces of respective front side and rear side
sheet sections, or rear side and front side sheet sections, along
an opening end of the bag, the opening end being located at an
upper en of the bag when the bag is in an upright state, wherein
the respective zipper tapes are bonded together at a position below
an engaging section of the zipper tapes, with heat sealing strength
of a degree that allows the bonded zipper tapes to be manually
peeled apart, by means of an interface peeling action, an
interlayer peeling action, or a cohesive peeling action.
2. The packaging bag with zipper according to claim 1, wherein one
of the zipper tapes is made from a hot melt type adhesive resin,
and the other zipper tape is made from a polyethylene type resin or
polypropylene type resin of a same kind as a material forming inner
layers of the bag.
3. The packaging bag with zipper according to claim 1, wherein
either one of the zipper tapes is made from a hot melt type
adhesive resin, and both the outer face and the inner face of the
other zipper tape are made from a polyethylene type resin or a
polypropylene type resin of a same kind as a material forming the
inner layer of the bag.
4. The packaging bag with zipper according to claim 1, wherein one
of the zipper tapes is made from a hot melt type adhesive resin,
and the other zipper tape is made to have an outer face made from a
polyethylene type resin or polypropylene type resin of a same kind
as a material forming inner layers of the bag, and to have an inner
face made from a polyethylene type resin or polypropylene type
resin of a different kind from the material forming the inner
layers of the bag.
5. The packaging bag with zipper according to claim 1, wherein the
inner faces of both zipper tapes are made from a polyethylene type
resin or polypropylene type resin, and a hot melt type adhesive
resin section is provided on the inner face of one of the zipper
tapes, at least in a bonding section formed by heat sealing below
the engaging section of the zipper tapes.
6. The packaging bag with zipper according to claim 1, wherein a
hot melt type adhesive resin section that is to be bonded to the
inner layer of the bag, is provided in at least the lower end
portion of the outer face of the zipper tape made from a
polyethylene type resin or a polypropylene type resin.
7. The packaging bag with zipper according to claim 1, wherein both
zipper tapes are made from a resin containing a material comprising
a random mixture of a straight-chain low-density polyethylene type
resin and a polybutene-1 resin.
8. The packaging bag with zipper according to claim 1, wherein a
resin section containing a material comprising a random mixture of
a straight-chain low-density polyethylene type resin and a
polybutene-1 resin is provided on the inner faces of both zipper
tapes, at least in a bonding section formed by heat sealing below
the engaging section of the zipper tapes.
9. The packaging bag with zipper according to claim 1, wherein the
male zipper tape and the female zipper tape are respectively
coloured with mutually different colours.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to a packaging bag with a
zipper.
[0003] 2. Description of the Related Art
[0004] A conventional packaging bag with zipper of this kind is
known from Utility Model Registration No. 2557256, for example. In
other words, a packaging bag is conventionally known wherein an
openable and closable zipper which performs a male and female
coupling action is provided at opposing positions of a bag in the
vicinity of the opening end thereof, and in an integral fashion
with the bag.
[0005] In a packaging bag of the kind disclosed in Utility Model
Registration No. 2557256 described above, which comprises an
integrally provided openable and closable zipper performing a male
and female coupling action, in most cases of a packaging bag with
zipper which is not provided with a slider, the perimeter of the
bag, including the edge adjacent to the opening end of the bag
close to a location of the zipper, is closed by heat sealing. Thus,
the bag cannot be opened by opening the zipper unless the heat seal
section along the edge adjacent to the opening end of the bag is
cut. There are also such bags, however, that are not heat sealed
along the edge adjacent to the opening end of the bag close to the
location of the zipper. Such bags can simply be opened by opening
the zipper at a shop display cabinet, for instance. If the bag is
then closed again after opening, it cannot be identified whether or
not it has been opened, posing management problems.
[0006] Furthermore, in the case of a packaging bag with zipper that
is provided with a slider, the zipper is provided along the opening
end of the bag and a slider is provided movably in the longitudinal
direction of the zipper, making it impossible to close the opening
end of the bag by heat sealing. Hence similar management problems
arise with this kind of packaging bags with zipper that are
provided with a slider.
SUMMARY OF THE INVENTION
[0007] The present invention was devised to resolve the problems,
an object thereof being to make it possible readily to identify
whether or not a packaging bag with zipper has been opened.
[0008] In order to achieve the object, the present invention is
devised as follows:
[0009] A packaging bag with zipper, in which the lower end portion
of a male zipper tape and the lower end portion of a female zipper
tape are bonded to the inner faces of respective front side and
rear side sheet sections, or rear side and front side sheet
sections, along the opening end of the bag. The upper end of the
bag comes at the top when the bag is in an upright state, and the
respective zipper tapes are bonded together at a position below the
engaging section thereof, with heat sealing strength of a degree
that allows the zipper tapes to be manually peeled apart, by means
of an interface peeling action, an interlayer peeling action, or a
cohesive peeling action.
[0010] In the packaging bag with zipper, either one of the zipper
tapes is made from a hot melt type adhesive resin, and the other
zipper tape is made from a polyethylene type resin or a
polypropylene type resin of the same kind as a material forming the
inner layers of the bag.
[0011] In the packaging bag with zipper, either one of the zipper
tapes is made from a hot melt type adhesive resin, and both the
outer face and the inner face of the other zipper tape are made
from a polyethylene type resin or a polypropylene type resin of the
same kind as a material forming the inner layer of the bag.
[0012] In the packaging bag with zipper, one of the zipper tapes is
made from a hot melt type adhesive resin, the outer face of the
other zipper tape is made from a polyethylene type resin or
polypropylene type resin of the same type as the material forming
the inner layers of the bag, and the inner face of the other zipper
tape is made from a polyethylene type resin or polypropylene type
resin of a different type from the material forming the inner
layers of the bag.
[0013] In the packaging bag with zipper, the inner faces of both
zipper tapes are made from a polyethylene type resin or
polypropylene type resin, and a hot melt type adhesive resin
section is provided on the inner face of one of the zipper tapes,
at least in a bonding section formed by heat sealing in a position
below the engaging section of the zipper tapes.
[0014] In the packaging bag with zipper, a hot melt type adhesive
resin section that is to be bonded to the inner layer of the bag,
is provided in at least the lower end portion of the outer face of
the zipper tape made from a polyethylene type resin or a
polypropylene type resin.
[0015] In the packaging bag with zipper, both zipper tapes are made
from a resin containing a material comprising a random mixture of a
straight-chain low-density polyethylene type resin and a
polybutene-1 resin.
[0016] In the packaging bag with zipper, a resin section containing
a material comprising a random mixture of a straight-chain
low-density polyethylene type resin and a polybutene-1 resin is
provided on the inner faces of both zipper tapes, at least in the
bonding section formed by heat sealing below the engaging section
of the zipper tapes.
[0017] In the packaging bag with zipper, the male zipper tape and
the female zipper tape are respectively coloured with mutually
different colours.
[0018] According to the foregoing, zipper tapes are bonded together
at a position below the engaging section of the zipper tapes, with
heat sealing strength that allows the bonding section of the zipper
tapes to be peeled apart by hand. Thus, if a user has mistakenly
opened the zipper and peeled apart the bonding section of the
zipper tapes, for example, it will be possible to confirm that the
packaging bag has been opened. In particular, by colouring the male
zipper tape and the female zipper tape, respectively with mutually
different colours, the bonding section of the zipper tapes can be
changed to a separate colour, by means of colour mixing, and if a
user has mistakenly opened the zipper and peeled apart the bonding
section of the zipper tapes, for example, the colour of the section
will revert to the original colours of the respective zipper tapes.
Thus, it is easy to identify whether or not the packaging bag has
been opened.
BRIEF DESCRIPTION OF THE DRAWINGS
[0019] FIG. 1 is a perspective view of a packaging bag with zipper
according to a first embodiment of the present invention;
[0020] FIG. 2 is an enlarged sectional view of a principal part of
this packaging bag with zipper;
[0021] FIG. 3 is an enlarged sectional view of the principal part
of this packaging bag with zipper, showing the bag in an open
state;
[0022] FIG. 4 is an enlarged sectional view of a principal part of
a packaging bag with zipper according to a second embodiment,
showing the bag in an open state;
[0023] FIG. 5 is an enlarged sectional view of a principal part of
a packaging bag with zipper according to a third embodiment,
showing the bag in an open state; and
[0024] FIG. 6 is an enlarged sectional view of a principal part of
a packaging bag with zipper according to a fourth embodiment,
showing the bag in an open state.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0025] In FIG. 1 to FIG. 3, numeral 1 denotes a packaging bag, and
this packaging bag 1 is closed by heat sealing at three edges,
namely, the lower end when the bag is in an upright state, and the
two respective side edges. Numeral 2 denotes the heat seal section
of the bag. Zipper tapes 5, 6 are provided in an integral fashion
at the opening end of the bag which comes at the top when the
packaging bag 1 is in an upright state, by heat sealing and bonding
the lower end portion of a male zipper tape 5 and a female zipper
tape 6 to the inner faces of respective sheet sections 3, 4 on the
front side and rear side (or rear side and front side) of the bag
1. In other words, the zipper tapes 5 and 6 are provided in such a
manner that they project from the upper end of the packaging bag
1.
[0026] The sheet sections 3, 4 forming the packaging bag 1 have a
two-layer structure in which the outer layers 3a, 4a thereof are
made from nylon film and the inner layers 3b, 4b are made from
polyethylene film, and the male zipper tape 5 and female zipper
tape 6 which are bonded to the inner faces of these respective
sheet sections 3, 4 along the opening end of the packaging bag 1
are made from materials described below.
[0027] For example, taking the material of the male zipper tape 5
as A and the material of the female zipper tape 6 as B, then A is a
hot melt type adhesive resin and B is a polypropylene type resin,
and a polyethylene type resin layer 7 and a hot melt type adhesive
resin layer 8 are formed respectively by combined extrusion on the
material A forming the male zipper tape 5 and material B forming
the female zipper tape 6, on the faces thereof which oppose the
inner faces 3b, 4b of the respective sheet sections 3, 4.
Thereupon, if the male zipper tape 5 and the female zipper tape 6
are heat sealed, respectively, onto the inner face of the sheet
section 3 and the inner face of the sheet section, at a temperature
of 180.degree. C., for example, a sealing time of one second, and a
sealing pressure of 20 N/cm.sup.2, then the polyethylene type resin
layer 7 of the zipper tape 5 and the inner layer 3b of the
polyethylene film of the sheet section 3 fuse together, and the hot
melt type adhesive resin layer 8 of the zipper tape 6 fuses with
the inner layer 4b of the polyethylene film of the sheet section 4.
In this case, the polyethylene type resin layer 7 of the zipper
tape 5 and the polyethylene film of the inner layer 3b of the sheet
section 3 are of the same type and become completely fused
together, and the hot melt type adhesive resin layer 8 of the
zipper tape 6 and the polyethylene film of the inner layer 4b of
the sheet section 4 are bonded together by a heat sealing strength
of approximately 5 N/15 mm. In other words, it was found on the
basis of experimentation, that the hot melt type adhesive resin has
characteristics whereby, when heated, it bonds with polyolefin type
resins, such as polyethylene, and has a heat sealing strength with
polyolefin type resins of 5 N/15 mm or above.
[0028] Furthermore, in the packaging bag 1 with zipper according to
the present embodiment, the respective zipper tapes 5, 6 are bonded
together by heat sealing along a lower end in the width direction
of the zipper portion when the packaging bag 1 is in an upright
state, in such a manner that the zipper tapes can be peeled apart
by an interface peeling action. Numeral 9 denotes a bonding section
between the zipper tapes 5, 6. Since the material of the zipper
tape 5 is a hot melt type adhesive resin, and the material of the
zipper tape 6 is a polypropylene type resin, the heat sealing
strength will be approximately 5 N/15 mm described above. This heat
sealing strength of approximately 5 N/15 mm is of a degree that
allows the zipper tapes to be peeled apart readily by hand. In the
present embodiment, a blue colouring agent is incorporated into the
hot melt type adhesive resin which is the material forming the
zipper tape 5, and a yellow colouring agent is incorporated into
the polypropylene type resin which is the material forming the
zipper tape 6, so that when the respective zipper tapes 5, 6 are in
a state of being bonded together by heat sealing, the colour of the
bonding section becomes green, due to the mixing of the colours.
Moreover, by fabricating both of the zipper tapes 5, 6 from a
transparent material, and performing coloration of the polyethylene
type resin layer 7 and the hot melt type adhesive resin 8 provided
on the outer sides thereof, using a blue colouring agent and a
yellow colouring agent, respectively, it is possible to make the
colour of the bonding section a green colour, by mixing the
colours, similarly to the foregoing, when the two zipper tapes 5, 6
are bonded together by heat sealing.
[0029] Since the engaging section 10 of the male zipper tape 5 and
the female zipper tape 6 will deform if heat is applied thereto,
only the lower end portions of the respective zipper tapes 5, 6
which overlap with the inner faces of the sheet sections 3, 4,
below the engaging section 10, are bonded by heat sealing. In the
drawings, 11 denotes a slider for opening and closing the zipper
tapes 5, 6.
[0030] Various types of hot melt type adhesive resin are known, but
in the present embodiment, it is possible to use, as a resin
suitable for bonding the zipper tapes 5, 6 together in such a
manner that they can be peeled apart by an interface peeling
action, for example, a resin formed from a resin composition
comprising at least one type of resin selected from a group
comprising ethylene ethylacrylate copolymer comprising a main
ingredient of ethylene vinyl acetate copolymer manufactured by
Hirodine Corp., and petroleum resins, turpentine resins and rosin
type resins.
[0031] Moreover, in the embodiment described above, the material of
the male zipper tape 5 is stated as a hot melt type adhesive resin,
and the material of the female zipper tape 6 is stated as a
polypropylene type resin, but a reverse configuration is also
possible. In this case, a hot melt type adhesive resin layer is
formed on the male zipper tape 5, and a polyethylene type resin
layer is formed on the female zipper tape 6.
[0032] Furthermore, with respect to the shape of the packaging bag
1, in addition to the embodiment described above, it is also
possible to use a gusset type, butt-seam type, or standing pack
type, or the like.
[0033] Moreover, in the embodiment described above, a slider is
provided on the zipper, but it is of course also possible to
implement the present invention with a zipper having no slider.
[0034] As described above, in the present embodiment, a product (a
bag containing contents) is arranged in a store display cabinet in
a state in which the lower end sections of respective zipper tapes
5, 6 are bonded together with heat sealing strength of a degree
that allows the bonding section of the zipper tapes to be readily
peeled apart by hand, at the height of the bonding section of the
tapes to the sheet sections 3, 4 of the packaging bag 1. Thus, if a
user has mistakenly opened the zipper and peeled apart the bonding
section 9 of the zipper tapes 5, 6, the colour (green) of the
bonding section 9 will revert to the colours of the respective
zipper tapes 5, 6 (blue, yellow) or, if the zipper tapes 5, 6 are
transparent, it will revert to the colours of the polyethylene type
resin layer 7 and the hot melt type adhesive resin layer 8 provided
on the outer sides thereof. Hence it will be possible to confirm
that the packaging bag 1 has been opened.
[0035] If the lower end sections of the zipper tapes 5, 6 are
bonded together in this manner with heat sealing strength of a
degree that allows the bonding section of the zipper tapes to be
peeled apart readily by hand, when a user buys a product and goes
to extract the contents from the bag 1, he or she can extract the
contents from the packaging bag 1 by opening the zipper and peeling
apart the bonding section 9 between the zipper tapes 5, 6. In this
case, the heat sealing strength of the bonding section 9 between
the zipper tapes 5, 6 is approximately the same as the heat sealing
strength between the inner face of the packaging bag 1 and the
female zipper tape 6 that is made of a polypropylene type resin and
has a hot melt type adhesive resin layer 8 provided on the surface
thereof. But since the bonding section 9 is situated at the lower
end section of the location of the zipper tapes, the female zipper
tape 6 and the packaging bag 1 are not liable to be peeled apart
when the bonding section 9 is peeled apart by means of the user's
fingers.
[0036] In the present embodiment, the zipper tape 5 is coloured
blue and the zipper tape 6 is coloured yellow, in such a manner
that the heat-sealed bonding section becomes green in colour, but
it is also possible to use other colour combinations. It is not
necessarily required to perform colouring of the zipper tapes 5, 6,
and when the bonding section 9 of the zipper tapes 5, 6 has been
peeled apart, it can be readily identified that the packaging bag 1
has been opened.
[0037] Moreover, in the embodiment described above, the two zipper
tapes 5, 6 are bonded together in such a manner that they can be
peeled apart by means of an interface peeling action, with heat
sealing strength of a degree that permits the tapes to be peeled
apart manually, at a position below the engaging section 10 of the
zipper tapes 5, 6. It is also possible to bond the zipper tapes
together by means of an interlayer peeling action or a cohesive
peeling action. For example, as a hot melt type adhesive resin used
for forming a cohesive peel, it would be suitable to use a polymer
alloyed resin containing a polyolefin known as VMX (registered
trademark) manufactured by Mitsubishi Chemical Corp. as a main
ingredient. The polymer alloyed resin essentially consists of a
multi-component polymer including a polyolefin resin which is
grafted with a radical polymerisation monomer and contains a
non-crystalline vinyl polymer in a uniform manner, and a polymer
including polyolefin dispersed with styrene in the dispersion phase
of polyolefin.
[0038] Furthermore, in the embodiment described above, the
packaging bag 1 is made from a synthetic resin fabricated from
sheet sections 3, 4 having a two-layer structure comprising nylon
film in the outer layers 3a, 4a and polyethylene film in the inner
layers 3b, 4b, but the materials used are not limited in particular
to these. In other words, provided that, at the least, a synthetic
resin film such as a polyethylene film or a polypropylene film, or
the like, is used to fabricate the inner layers, due to the
requirements of heat sealing, it is possible to use a material
other than a synthetic resin, such as aluminium foil, paper, rayon
paper, or the like, as a material to be laminated on the outer
sides of the inner layers.
[0039] Moreover, in the embodiment described above, in the male
zipper tape 5 made from a hot melt type adhesive resin and the
female zipper tape 6 made from a propylene type resin, a
polyethylene type resin layer 7 and a hot melt type adhesive resin
layer 8 are formed respectively on the faces opposing the inner
layers 3b, 4b of the respective sheet sections 3, 4 but whilst the
hot melt type adhesive resin layer 8 provided on the side of the
female zipper tape 6 made from a polypropylene type resin is
required, it is possible to omit the polyethylene type resin layer
7 provided on the side of the male zipper tape 5 made from a hot
melt type adhesive resin. Moreover, it is also possible to make the
male zipper tape or the female zipper tape from a hot melt type
adhesive resin, and to make the other zipper tape from a
polyethylene type resin, and in this case, since the other zipper
tape made from a polyethylene type resin is of the same type as the
polyethylene film on the inner layer 3b of the sheet section 3, it
will fuse completely with same, and the zipper tape made from a hot
melt type adhesive resin and the polyethylene film on the inner
layer 4b of the sheet section 4 will be bonded together by a heat
sealing strength of approximately 5 N/15 mm, similarly to the
embodiment described above. Moreover, the heat sealing strength
between the zipper tapes may also be approximately 5 N/15 mm, and
the two zipper tapes may be bonded together on the basis of an
interface peeling action, as in the embodiment described above, or
a interlayer peeling action, or a cohesive peeling action.
Furthermore, a composition may also be adopted wherein one of the
zipper tapes is made from a hot melt type adhesive resin, and the
outer face of the other zipper tape is made from a polyethylene
type resin, whilst the inner face thereof is made from a
polypropylene type resin which is different to the material forming
the inner layer of the packaging bag 1.
[0040] Furthermore, in the embodiment described above, the zipper
tapes 5, 6 are bonded by heat sealing to the inner faces of the
respective sheet sections 3, 4 of the packaging bag 1, but it is
also possible for the two zipper tapes 5, 6 to be installed on the
inner faces of the respective sheet sections 3, 4 of the packaging
bag 1 by being laid respectively over the inner faces of the sheet
sections 3, 4 of the packaging bag 1 in a sheet state, and bonded
to same, whilst the zipper tapes 5, 6 are in a molten state
directly after molten extrusion.
[0041] FIG. 4 shows a second embodiment of the present
invention.
[0042] The second embodiment illustrated in FIG. 4 is a
modification of the first embodiment shown in FIG. 1-FIG. 3.
Whereas in the first embodiment, the male zipper tape 5 and the hot
melt type adhesive resin layer 8 provided on the outer face of the
female zipper tape 6 are made entirely from a hot melt type
adhesive resin, in the second embodiment, the male zipper tape 5 is
made from a polyethylene type resin of the same kind as the inner
layer 3b of the packaging bag 1, and the female zipper tape 6 is
made from a polypropylene type resin, a section 12 made from a hot
melt type adhesive resin being provided on the inner face of the
male zipper tape 5 only in the vicinity of the bonding section 9
between the zipper tapes 5, 6, and a section 13 made from a hot
melt type adhesive resin bonded to the inner layer 4b of the
packaging bag 1 being provided on the outer face of the lower end
section of the female zipper tape 6. It is also possible to provide
a section made from a polyethylene type resin of the same kind as
the inner layer 4b of the packaging bag 1, instead of the section
13 made from a hot melt type adhesive resin. Even if a hot melt
type adhesive resin section is provided in a minimum necessary area
at a position below the engaging section 10 of the zipper tapes 5,
6 in this way, similar effects to those of the first embodiment can
still be obtained. In this embodiment, if the male zipper tape 5 is
made from a hot melt type adhesive resin, the section 12 made from
a hot melt type adhesive resin can be omitted.
[0043] FIG. 5 shows a third embodiment of the present
invention.
[0044] In the third embodiment shown in FIG. 5, the male zipper
tape 5 and the female zipper tape 6 are both made from a
polyethylene type resin of the same type as forming the inner
layers 3b, 4b of the packaging bag 1, and a section 14 made from a
hot melt type adhesive resin is provided on the inner face of the
female zipper tape 6, only in the vicinity of the bonding section 9
of the zipper tapes 5, 6.
[0045] Furthermore, both the zipper tapes 5, 6 are made from a
resin containing a random mixture of a straight-chain type
low-density polyethylene resin and a polybutene-1 resin, for
example, as means for bonding the zipper tapes 5, 6 together in a
readily peelable manner, in a position below the engaging section
10, with heat sealing strength of a degree that allows the zipper
tapes to be manually peeled apart. Thus, the bonding section 9
along the lower end section of the zipper tapes 5, 6 fabricated
from the foregoing material will not couple completely, and hence
it will be possible to peel apart the bonding section 9 of the
zipper tapes 5, 6, readily and manually, by means of a cohesive
peeling action.
[0046] FIG. 6 shows a fourth embodiment of the present
invention.
[0047] In the fourth embodiment shown in FIG. 6, both of the zipper
tapes 5, 6 are made from a polyethylene type resin of the same type
as forming the inner layers 3b, 4b of the packaging bag 1, and
resin sections 15, 16 containing a resin comprising a random
mixture of a straight-chain low-density polyethylene type resin and
a polybutene-1 resin are provided on the inner faces of the two
zipper tapes 5, 6 at least in the vicinity of the bonding section 9
located below the engaging section 10 of the zipper tapes 5, 6.
This also causes the bonding section 9 in the lower end section of
the zipper tapes 5, 6 not to couple together completely, and hence
it will be possible to peel apart the bonding section 9 of the
zipper tapes 5, 6 readily and manually by means of a cohesive
peeling action.
[0048] In the embodiment illustrated in the drawings, the
respective zipper tapes 5, 6 may have a structure comprising three
or more layers. In other words, it is possible to interpose between
the inner face and the outer face of the zipper tapes 5, 6, by
using a adhesive resin, a material other than a polyethylene type
resin or a polypropylene type resin, a hot melt type adhesive
resin, or a resin containing a random mixture of a straight-chain
type low-density polyethylene type resin and a polybutene-1
resin.
[0049] Furthermore, in the foregoing description, the bonding
section 9 of the zipper tapes 5, 6 is bonded with a heat seal
strength of approximately 5 N/15 mm, but it may be sufficient if
the heat sealing strength is 1 N/15 mm or above.
* * * * *