U.S. patent application number 10/561932 was filed with the patent office on 2007-06-07 for double wall bags.
This patent application is currently assigned to Flexipol Packaging Ltd.. Invention is credited to Paul Stuart Brassington, Patrick Thomas Connelly, John Joseph Dermot Griffiths, Ian John Smith.
Application Number | 20070127855 10/561932 |
Document ID | / |
Family ID | 27637372 |
Filed Date | 2007-06-07 |
United States Patent
Application |
20070127855 |
Kind Code |
A1 |
Smith; Ian John ; et
al. |
June 7, 2007 |
Double wall bags
Abstract
The invention relates to plastic bags and sack for use
especially in the food and pharmaceutical industries. The bag (2)
comprises inner and outer bag sections (4, 14) which are joined at
least at an upper portion in a manner which allows them to be
separated when required, such as by heat sealing. The outer bag
section (14) may be provided with a mouth (10) through which the
inner bag section can be withdrawn when required. Alternatively,
the outer bag section may be peeled away from the inner bag
section. The inner bag section is heat sealed after filling with
contents to retain the contents in the inner portion. The heat
sealing step also serves to secure the bag sections together as
above. The inner bag section is preferably provided with a
closeable mouth (132) separate from the end by which it is filled,
through which the contents may be dispensed.
Inventors: |
Smith; Ian John; (Prescot,
GB) ; Griffiths; John Joseph Dermot; (Burnley,
GB) ; Connelly; Patrick Thomas; (Newton, GB) ;
Brassington; Paul Stuart; (Burnley, GB) |
Correspondence
Address: |
TROUTMAN SANDERS LLP
600 PEACHTREE STREET , NE
ATLANTA
GA
30308
US
|
Assignee: |
Flexipol Packaging Ltd.
Rossendale
GB
BB4 5HH
|
Family ID: |
27637372 |
Appl. No.: |
10/561932 |
Filed: |
June 28, 2004 |
PCT Filed: |
June 28, 2004 |
PCT NO: |
PCT/GB04/02780 |
371 Date: |
May 5, 2006 |
Current U.S.
Class: |
383/111 ;
383/66 |
Current CPC
Class: |
B65D 31/04 20130101;
B65D 33/004 20130101; B65D 33/22 20130101 |
Class at
Publication: |
383/111 ;
383/066 |
International
Class: |
B65D 30/08 20060101
B65D030/08; B65D 33/16 20060101 B65D033/16 |
Foreign Application Data
Date |
Code |
Application Number |
Jun 26, 2003 |
GB |
0314885.5 |
Claims
1. A plastic bag comprising: i) a cover section comprising first
and second opposed walls; ii) a bag section comprising third and
fourth opposed walls joined at their side and base edges and an
open end by means of which the bag section may be filled with
contents, the first and second walls being arranged to enclose the
bag section; iii) a closeable mouth defined in a wall of the bag
section for access in use to the interior of the bag section; iv) a
closeable region, distinct from the mouth, including an end portion
of the cover section and an end portion of the bag section
proximate the open end of the bag section, within which closeable
region the bag section may be sealed closed after filling; wherein,
in the closeable region, an internal face of at least one of the
respective first and second walls is attached and/or attachable to
an adjacent external face of a wall of the bag section, the
attachment being such that the bag section is separable in use from
the cover section without compromising the seal of the bag section
in the closeable region.
2. A plastic bag as claimed in claim 1 wherein the open end of the
bag section may operatively be sealed after filling by heat sealing
the bag section walls together in the closeable region.
3. A plastic bag as claimed in claim 1 wherein, for attachment of
the cover section to the bag section in said closeable region, an
internal face of at least one of the respective first and second
walls of the cover section is attachable to at least one external
face of a bag section wall by heat sealing in the closeable
region.
4. A plastic bag as claimed in claim 3 wherein at least one member
selected from the group comprising the internal faces of the first
and second walls and the respective external faces of the bag
section walls comprises a first treated area in the closeable
region, said first treated area being effective to limit the
strength of the heat seal between the cover section and bag
section.
5. A plastic bag as claimed in claim 4 wherein said first treated
area comprises printed areas, the printed areas being resistant to
heat sealing.
6. A plastic bag as claimed in claim 1 wherein the first and second
walls are also separably attached respectively to the bag section
walls in areas other than said closeable region.
7. A plastic bag as claimed in claim 6 wherein the first and second
walls are removeably heat sealed respectively to the bag section
walls in said separably attached areas.
8. A plastic bag as claimed in claim 1 wherein at least one of the
first wall and the adjacent bag section wall and/or at least one of
the second wall and the adjacent bag section wall comprises a
second treated area, said second treated area being effective to
limit the strength of the heat seal between respectively the first
and third and the second and fourth walls in said separably
attached areas.
9. A plastic bag as claimed in claim 8 wherein said second treated
area comprises printed areas, the printed areas being resistant to
heat sealing.
10. A plastic bag as claimed in claim 3, wherein said first treated
area extends across the whole inner surface of the first and/or
second wall.
11. A plastic bag as claimed in claim 10 wherein the first and
second walls are also separably attached respectively to the bag
section walls in areas other than said closeable region.
12. A plastic bag as claimed in claim 11 wherein the first and
second walls are removeably heat sealed respectively to the bag
section walls in said separably attached areas.
13. A plastic bag as claimed in claim 5 comprising, in a said
treated area, alternate printed and non-printed areas.
14. A plastic bag as claimed in claim 13 wherein the area of the
printed areas is greater than the area of the non-printed
areas.
15. A plastic bag as claimed in claim 13 wherein the printed and
non-printed areas alternate to define stripes across the closeable
region and/or across the separably attached areas.
16. A plastic bag as claimed in claim 13 wherein the non-printed
areas have a width of not more than about 2 mm.
17. A plastic bag as claimed in claim 13 wherein the printed areas
have a width of not more than about 10 mm.
18. A plastic bag as claimed in claim 4 wherein the treated area
comprises an embossed area of one or more of the walls.
19. A plastic bag as claimed in claim 1 wherein the cover section
is longer than the bag section such that the cover section extends
beyond the base end of the bag section, the first and second walls
being joined to each other in said lengthwise extending
portion.
20. A plastic bag as claimed in claim 1 wherein the width of the
cover section is greater than the width of the bag section such
that the cover section extends beyond the side edges of the bag
section, the first and second walls being joined to each other in
said widthwise extending portion.
21. A plastic bag as claimed in claim 6 wherein the width of the
cover section is greater than the width of the bag section such
that the cover section extends beyond the side edges of the bag
section, the first and second walls being joined to each other in
said widthwise extending portion.
22. A plastic bag as claimed in claim 1 further comprising: a first
closure flap overlying and closing said mouth defined in a wall of
said bag section said first closure flap including a first attached
region which is peelably attached to said bag section wall such
that at least a portion of said first closure flap may be peeled
away from said bag section wall across the peelably attached region
to reveal the mouth, and, optionally, a second attached region
spaced from the peelably attached region in which second region
said first closure flap is also attached to said bag section
wall.
23. A plastic bag as claimed in claim 1 comprising: a first closure
flap overlying and closing said mouth defined in a wall of said bag
section said first closure flap including a first region which is
attached to a said bag section wall, said first closure flap
including at least one line of weakness defining a tearable portion
of said first closure flap within which tearable portion said first
closure flap is not attached to the bag section wall and which
tearable portion can be opened by tearing along the line of
weakness to reveal the mouth; and, optionally, a second attached
region spaced from the tearable portion in which second region said
first closure flap is also attached to said bag section wall.
24. A plastic bag as claimed in claim 22 wherein the first closure
flap extends into the closeable region.
25. A bag as claimed in claim 24 further comprising a closure flap;
wherein, for attachment of the cover section to the bag section in
said closeable region, an internal face of at least one of the
respective first and second walls of the cover section is
attachable to at least one external face of a bag section wall by
heat sealing in the closeable region; wherein at least one member
selected from the group comprising the internal faces of the first
and second walls and the respective external faces of the bag
section walls comprises a first treated area in the closeable
region, said first treated area being effective to limit the
strength of the heat seal between the cover section and bag
section; wherein the first closure flap is overlying and closing
said mouth defined in a wall of said bat section said first closure
flap including a first attached region which is peelably attached
to said bag section wall such that at least a portion of said first
closure flap may be peeled away from said bag section wall across
the peelably attached region to reveal the mouth, and, optionally,
a second attached region spaced from the peelably attached region
in which second region said first closure flap is also attached to
said bag section wall; and wherein a first treated area is formed
on the first closure flap instead of a treated area of the bag
section.
26. A plastic bag according to claim 1 wherein on or both of the
respective first and second walls of the cover section is/are
adhered to the bag section proximate the open end of the bag
section.
27. A plastic bag as claimed in claim 26 wherein the cover section
is adhered to the bag section at marginal portions of the closeable
region.
28. A plastic bag as claimed in claim 1 further comprising a second
closeable mouth defined in the first or second wall of the cover
section for access in use to the bag section.
29. A plastic bag as claimed in claim 1 further comprising: a
second closure flap including a first region which is peelably
attached to said cover section wall such that at least a portion of
the closure flap may be peeled away from said cover section wall
across the peelably attached region and a second attached region
spaced from the peelably attached region in which second region the
second closure flap is also attached to said cover section
wall.
30. A plastic bag as claimed in claim 1 further comprising: a
second closure flap including a first region which is attached to
said cover section wall, the second closure flap including at least
one line of weakness defining a tearable portion of the closure
flap within which tearable portion the closure flap is not attached
to said cover section wall and which tearable portion can be opened
by tearing along the line of weakness and a second attached region
spaced from the tearable portion in which second region the second
closure flap is also attached to said cover section wall.
31. A plastic bag as claimed in claim 29 wherein the second closure
flap is arranged to cover the second mouth.
32. A plastic bag as claimed in claim 1 further comprising gripping
means formed in or on, or attached to the first or second walls, to
facilitate gripping of said walls on separation of the cover
section from the bag section.
33. A method of handling a flowable product comprising: i)
providing a bag as claimed in claim 1; ii) filling the bag section
with the flowable product through the open end of the bag; and iii)
applying heat sealing means to the closeable region thereby to heat
seal the bag section walls together to sealingly close the bag
section and to heat seal the first and/or second walls to the bag
section walls to separably attach cover section and bag section
together.
34. A method as claimed in claim 33 further comprising: iv)
separating the cover section from the bag section in the closeable
region; v) if necessary, separating the cover section from the bag
section outside the closeable region and vi) withdrawing the bag
section from the cover section.
35. A plastic bag comprising: i) a cover section comprising first
and second opposed walls; ii) a product containing bag section
comprising third and fourth opposed walls joined at their side and
base edges, the first and second walls being arranged to enclose
the bag section; iii) a closeable mouth defined in a wall of the
bag section for access in use to the interior of the bag section;
iv) a sealing region, distinct from the mouth, including an end
portion of the cover section and an end portion of the bag section
within which sealing region the bag section is sealed closed after
filling bag section with product; wherein, in the sealing region,
an internal face of at least one of the respective first and second
walls is attached to an adjacent external face of a wall of the bag
section, the attachment being such that the bag section is
separable in use from the cover section without compromising the
seal of the bag section in the sealing region.
36. A plastic bag as claimed in claim 35 wherein, within the
sealing region the respective first and second walls of the cover
section are attached to at least one of the external faces of the
respective bag section walls of the bag section by means of a heat
seal formed contemporaneously with the heat seal which seals the
bag section walls.
37. A plastic bag as claimed in claim 36 wherein at least one of
the internal faces of the first and second walls and the external
faces of the bag section walls comprises a treated area in the
sealing region, the treated area being effective to limit the
strength of the heat seal between the cover section and bag
section.
38. A plastic bag as claimed in claim 35 further comprising: a
first closure flap overlying and closing said mouth defined in a
wall of said bag section said first closure flap including a first
attached region which is peelably attached to said bag section wall
such that at least a portion of said first closure flap may be
peeled away from said bag section wall across the peelably attached
region to reveal the mouth, and, optionally, a second attached
region spaced from the peelably attached region in which second
region said first closure flap is also attached to said bag section
wall.
39. A plastic bag as claimed in claim 35 comprising: a first
closure flap overlying and closing said mouth defined in a wall of
said bag section said first closure flap including a first region
which is attached to a said bag section wall, said first closure
flap including at least one line of weakness defining a tearable
portion of said first closure flap within which tearable portion
said first closure flap is not attached to the bag section wall and
which tearable portion can be opened by tearing along the line of
weakness to reveal the mouth; and, optionally, a second attached
region spaced from the tearable portion in which second region said
first closure flap is also attached to said bag section wall.
40. A plastic bag as claimed in claim 38 wherein the first closure
flap extends into the closeable region.
41. A bag as claimed in claim 40 wherein at least one of the
internal faces of the first and second walls and the external faces
of the bag section walls comprises a treated area in the sealing
region, the treated area being effective to limit the strength of
the heat seal between the cover section and bag section; and
further comprising: a first closure flap overlying and closing said
mouth defined in a wall of said bag section said first closure flap
including a first attached region which is peelably attached to
said bag section wall such that at least a portion of said first
closure flap may be peeled away from said bag section wall across
the peelably attached region to reveal the mouth, and, optionally,
a second attached region spaced from the peelably attached region
in which second region said first closure flap is also attached to
said bag section wall; wherein a first treated area is formed on
the first closure flap instead of a treated area of the bag
section.
42. (canceled)
Description
[0001] The present invention relates to bags and sacks and in
particular to plastic bags and sacks for use in the food and
pharmaceutical industries, especially for the storage and transport
of powdery or granular materials, other flowable solid materials or
the like.
[0002] The food and pharmaceutical industries necessarily place
stringent requirements on the handling of ingredients and
components, as well as on final products sold to commercial users
and consumers. These requirements are essential to prevent
contamination with dust, dirt or other foreign bodies, or with, for
example, bacteria. Conventional bags and sacks have tended to use
at least one layer, usually an outer layer, of a paper-based
material which is closed by stitching. This sort of construction
has the significant disadvantage that, on opening of the bag,
pieces of paper or stitching thread may contact and become mixed
with the contents of the bag. Other bags are made of plastics
material and suffer a similar problem in that the closure of the
bag often requires the bag to be cut open to access the contents.
This carries the danger that shards of plastic from the cutting
step can contact the bag contents.
[0003] The present invention seeks to overcome these problems by
providing a plastic bag or sack with an easy open closure which
does not require any cutting and which does not generate any loose
pieces or shards of plastic or other material on opening. The
present invention further seeks to provide a plastic bag or sack
wherein the portion of the bag containing product is maintained in
a clean, hygienic environment--for example during transport and
storage--until the bag is to be opened. More specifically, the
present invention provides a bag comprising an inner bag portion
and an outer cover portion, both portions being closeable after the
inner portion is filled with contents and the inner bag portion
being removable or separable from the outer portion without
disrupting the closure of the inner bag portion.
[0004] According to a first aspect of the present invention there
is provided a plastic bag comprising: [0005] i) a cover section
comprising first and second opposed walls; [0006] ii) a bag section
comprising third and fourth opposed walls joined at their side and
base edges and an open end by means of which the bag section may be
filled with contents, the first and second walls being arranged to
enclose the bag section; [0007] iii) a closeable mouth defined in a
wall of the bag section for access in use to the interior of the
bag section; [0008] iv) a closeable region, distinct from the
mouth, including an end portion of the cover section and an end
portion of the bag section proximate the open end of the bag
section, within which closeable region the bag section may be
sealed closed after filling; [0009] wherein, in the closeable
region, an internal face of at least one of the respective first
and second walls is attached and/or attachable to an adjacent
external face of a wall of the bag section, the attachment being
such that the bag section is separable in use from the cover
section without compromising the seal of the bag section in the
closeable region.
[0010] Preferably the open end of the bag section may operatively
be sealed after filling by heat sealing the bag section walls
together in the closeable region.
[0011] In a preferred embodiment of the invention, for attachment
of the cover section to the bag section in said closeable region,
an internal face of at least one of the respective first and second
walls of the cover section is attachable to at least one external
face of a bag section wall by heat sealing in the closeable region.
Preferably this heat sealing is effected in the same operation by
which the bag section walls are sealed together In the closeable
region.
[0012] Preferably at least one member selected from the group
comprising the internal faces of the first and second walls and the
respective external faces of the bag section walls comprises a
first treated area in the closeable region, said first treated area
being effective to limit the strength of the heat seal between the
cover section and bag section. Thus at least one of the walls of
the cover section and/or of the bag section includes such a first
treated area, whereby the resulting strength of the heat seal is
insufficient to prevent intentional separation of the bag section
from the cover section by a user. The heat seal is, nevertheless
strong enough to maintain the union between the cover section and
the bag section in the closeable region until separation of the
respective sections is desired.
[0013] In a particularly preferred embodiment said first treated
area comprises coated or printed areas, zones or regions
(hereinafter "printed areas"), the printed areas being resistant to
heat sealing. Thus little or no heat seal is formed within the
printed areas, but a heat seal is formed outside the printed areas,
the result being a weaker heat seal across the treated area taken
as a whole.
[0014] In a preferred variation of the bag of the invention the
first and second walls are also separably attached respectively to
the bag section walls in areas other than said closeable region.
Preferably in this variation the first and second walls are
substantially co-extensive with the width of the bag section walls.
The width of the cover section walls should not be less than that
of the bag section walls, but may be more. Most preferably, the
first and second walls are separably attached to the bag section
walls in areas proximate the side edges of the bag section.
[0015] Preferably in this variation the first and second walls are
removeably heat sealed respectively to the bag section walls in
said separably attached areas.
[0016] More preferably in this variation at least one of the first
wall and the adjacent bag section wall and/or at least one of the
second wall and the adjacent bag section wall comprises a second
treated area, said second treated area being effective to limit the
strength of the heat seal between respectively the first and third
and the second and fourth walls in said separably attached areas.
Preferably said second treated area comprises printed areas, the
printed areas being resistant to heat sealing.
[0017] The first and/or second treated areas may comprise, in a
said treated area, alternate printed and non printed areas. The
relative areas of the printed and non printed areas can be
determined by one skilled in the art by simple experiment in order
to achieve a union between the walls of appropriate strength,
allowing the walls to be separated when desired. This may depend,
for example, on the materials from which the walls are made and the
characteristics of the particular heat sealing apparatus which is
used. Preferably, however, the area of the printed areas is greater
than the area of the non-printed areas.
[0018] In a particularly preferred arrangement, the printed and
non-printed areas alternate to define stripes across the closeable
region and/or across the separably attached areas. In preferred
examples, typically the non-printed areas have a width of not more
than about 2 mm, preferably about 0.5 mm to 1.5 mm and typically
the printed areas have a width of not more than about 10 mm,
preferably about 3 mm to about 8 mm, more especially about 5
mm.
[0019] In a particularly preferred form of the invention, the whole
surface of a wall comprises with a treated area. For example the
whole inner surface of the first and/or may comprise a treated
area. Likewise, the whole external surface of the third and/or
fourth walls may comprise a treated area. The external surface of
the first and second closure flaps (where present) may also
comprise a treated area. In the most preferred arrangement, the
whole of the inner surface of the first and second walls comprises
a treated area, the surfaces of the third and fourth walls not
being coated or printed and, where present the surfaces of the
closure flap(s) not being treated. It is especially preferred that
the whole inner surfaces of the first and second walls are printed
or otherwise coated with alternating printed and non printed areas
in a pattern of stripes as described in the preceding
paragraph.
[0020] In an alternative (or additional) arrangement, the treated
area may comprise an embossed area of one or more of the walls.
[0021] In another preferred form of the invention the cover section
is longer than the bag section such that the cover section extends
beyond the base (lower) end of the bag section, the first and
second walls being joined to each other in said lengthwise
extending portion. For example, in the lengthwise extending
portion, the first and second walls may be joined to one another by
a permanent or separable heat seal at the edges of said walls.
[0022] In one alternative preferred arrangement the width of the
cover section is greater than the width of the bag section such
that the cover section extends beyond the side edges of the bag
section, the first and second walls being joined to each other in
said widthwise extending portion. For example, in the widthwise
extending portion, the first and second walls may be joined to one
another by a permanent or separable heat seal at the edges of said
walls. Preferably, but not essentially, in this arrangement the
first and second walls are not attached respectively to the bag
section walls in areas other than said closeable region.
[0023] In a particularly preferred embodiment the plastic bag of
the invention further comprises: [0024] a first closure flap
overlying and closing said mouth defined in a wall of said bag
section, said first closure flap including a first attached region
which is peelably attached to said bag section wall such that at
least a portion of said first closure flap may be peeled away from
said bag section wall across the peelably attached region to reveal
the mouth, and, optionally, a second attached region spaced from
the peelably attached region in which second region said first
closure flap is also attached to said bag section wall.
[0025] In an alternative, but functionally substantially
equivalent, embodiment the plastic bag of the invention further
comprises: [0026] a first closure flap overlying and closing said
mouth defined in a wall of said bag section and including a first
region which is attached to a said bag section wall, said first
closure flap including at least one line of weakness defining a
tearable portion of said first closure flap within which tearable
portion said first closure flap is not attached to the bag section
wall and which tearable portion can be opened by tearing along the
line of weakness to reveal the mouth; and, optionally, a second
attached region spaced from the tearable portion in which second
region said first closure flap is also attached to said bag section
wall.
[0027] Preferably in these embodiments the first closure flap
extends into the closeable region. In this case a first treated
area may be formed on the first closure flap instead of a treated
area of the bag section. That is, a first treated area on an
external face of a bag section wall is then no longer required and
is provided instead on the first closure flap. In one variation,
the wall of the bag section to which the closure flap is attached
may be made shorter than the other wall of the bag section, the
closure flap then acting as an extension of the bag section wall to
which it is attached.
[0028] In another embodiment of the invention one or both of the
respective first and second walls of the cover section is/are
adhered to the bag section proximate the open end of the bag
section. This may be in addition to the heat sealing in the
closeable region as defined above. Preferably in this case the
cover section is adhered to the bag section at marginal portions of
the closeable region.
[0029] In another embodiment of the invention, the plastic bag
further comprises a second closeable mouth defined in the first or
second wall of the cover section for access in use to the bag
section. This embodiment is applicable both to the case where the
cover section extends widthwise beyond the bag section (more
especially where the edges of the first and second walls in the
widthwise extending portion are permanently joined together, so
that the bag section can then be withdrawn from the cover section
through the second closeable mouth) and to the case where the cover
section and the bag section have nominally the same width.
[0030] In a preferred variation of this embodiment, the plastic bag
further comprises: [0031] a second closure flap including a first
attached region which is peelably attached to said cover section
wall such that at least a portion of the closure flap may be peeled
away from said cover section wall across the peelably attached
region and a second attached region spaced from the peelably
attached region in which second region the second closure flap Is
also attached to said cover section wall.
[0032] In an alternative, but substantially functionally equivalent
variation, the plastic bag further comprises: [0033] a second
closure flap including a first region which is attached to said
cover section wall, the second closure flap including at least one
line of weakness defining a tearable portion of the closure flap
within which tearable portion the closure flap is not attached to
said cover section wall and which tearable portion can be opened by
tearing along the line of weakness and a second attached region
spaced from the tearable portion in which second region the second
closure flap is also attached to said cover section wall.
[0034] Where the plastic bag further comprises a second closeable
mouth defined in the first or second wall of the cover section for
access in use to the bag section, the second closure flap (in
either of the above alternative constructions) is arranged to cover
the mouth so that when the second closure flap is peeled or torn
back, the mouth is revealed.
[0035] As an alternative to, or in addition to, the second closure
flap the plastic bag may preferably comprise gripping means formed
in or on, or attached to the first or second walls, to facilitate
gripping of said walls on separation of the cover section from the
bag section.
[0036] According to a second aspect of the invention there is
provided a method of handling a flowable product comprising: [0037]
i) providing a bag according to the first aspect of the invention;
[0038] ii) filling the bag section with the flowable product
through the open end of the bag; and [0039] iii) applying heat
sealing means to the closeable region thereby to heat seal the bag
section walls together to sealingly close the bag section and to
heat seal the first and/or second walls to the bag section walls to
separably attach the cover section and bag section together.
[0040] Preferably the method further comprises: [0041] iv)
separating the cover section from the bag section in the closeable
region; [0042] v) if necessary, separating the cover section from
the bag section outside the closeable region and [0043] vi)
withdrawing the bag section from the cover section.
[0044] According to a third aspect of the invention there is
provided a plastic bag comprising: [0045] i) a cover section
comprising first and second opposed walls; [0046] ii) a product
containing bag section comprising third and fourth opposed walls
joined at their side and base edges, the first and second walls
being arranged to enclose the bag section; [0047] iii) a closeable
mouth defined in a wall of the bag section for access in use to the
interior of the bag section; [0048] iv) a sealing region, distinct
from the mouth, including an end portion of the cover section and
an end portion of the bag section within which sealing region the
bag section is sealed closed after filling bag section with
product; [0049] wherein, in the sealing region, an internal face of
at least one of the respective first and second walls is attached
to an adjacent external face of a wall of the bag section, the
attachment being such that the bag section is separable in use from
the cover section without compromising the seal of the bag section
in the sealing region.
[0050] Preferably, within the sealing region, the respective first
and second walls of the cover section are attached to at least one
of the external faces of the respective bag section walls of the
bag section by means of a heat seal formed contemporaneously with
the heat seal which seals the bag section walls.
[0051] Preferably at least one of the Internal faces of the first
and second walls and the external faces of the bag section walls
comprises a treated area in the sealing region, the treated area
being effective to limit the strength of the heat seal between the
cover section and bag section.
[0052] In a preferred embodiment of this aspect of the invention,
the plastic bag further comprises: [0053] a first closure flap
overlying and closing said mouth defined in a wall of said bag
section, said first closure flap including a first attached region
which is peelably attached to said bag section wall such that at
least a portion of said first closure flap may be peeled away from
said bag section wall across the peelably attached region to reveal
the mouth, and, optionally, a second attached region spaced from
the peelably attached region in which second region said first
closure flap is also attached to said bag section wall.
[0054] In an alternative, but functionally substantially equivalent
embodiment of this aspect of the invention, the plastic bag
comprises [0055] a first closure flap overlying and closing said
mouth defined in a wall of said bag section said first closure flap
including a first region which is attached to a said bag section
wall, said first closure flap including at least one line of
weakness defining a tearable portion of said first closure flap
within which tearable portion said first closure flap is not
attached to the bag section wall and which tearable portion can be
opened by tearing along the line of weakness to reveal the mouth;
and, optionally, a second attached region spaced from the tearable
portion in which second region said first closure flap is also
attached to said bag section wall.
[0056] In a preferred variation the first closure flap extends into
the closeable region. Preferably in this variation a first treated
area is formed on the first closure flap instead of a treated area
of the bag section. More preferably, a treated area is provided
across the whole of one or both of the first and second walls and,
preferably, no treated area is provided on the bag section.
[0057] For a better understanding of the invention and to show how
the same may be carried into effect reference will be made, by way
of example only, to the following drawings, in which:
[0058] FIG. 1 is a partially cut away plan view of a bag according
to one embodiment of the invention;
[0059] FIG. 2A is a cross-section along the line II-II of FIG.
1;
[0060] FIG. 2B is similar to FIG. 2A showing a variation in the
construction of a closure flap;
[0061] FIG. 3 is a partially cut away plan view of the bag of FIG.
1 from the reverse side;
[0062] FIG. 4 is a simplified plan view of an alternative
construction of a closure flap of the bag of the invention;
[0063] FIG. 5 is a representation of treated and non-treated areas
on a cover section or bag section wall of the invention;
[0064] FIG. 6 is a partially cut away plan view of a bag according
to a second embodiment of the invention;
[0065] FIG. 7 is a cross-section along line VII-VII of FIG. 6;
and
[0066] FIG. 8 is similar to FIG. 7, showing a further closure flap
on the exterior of the bag.
[0067] Referring now to the FIGS. 1 to 4, the bag 2 of the this
embodiment comprises a cover section 4 defined by first and second
opposed walls 10, 12 and a bag section 14 defined by third and
fourth opposed walls 16, 18. The bag section 14 is smaller than the
cover section 4 and lies within the cover section 4. The cover
section 4 is closed on opposed side edges 20 and lower (base) end
edge 22 by suitable means for joining the first and second walls
together, such as adhesive or, more preferably, heat welding or
heat sealing. The opposed side edges 20 may be joined together in a
permanent or (preferably) separable manner. The bag section 14 is
closed on opposed side edges 24 and lower (base) end edge 26 by
suitable means for joining the third and fourth walls together.
Alternatively, the respective first and second walls and third and
fourth walls may be formed integrally, as a flattened tube. At end
28 the first and second walls 10, 12 are not joined to each other.
The third and fourth walls 16, 18 define an open end of the bag 30,
the walls 16, 18 also not being joined to each other at this end.
In FIGS. 1 to 3, the ends 28, 30 are shown slightly displaced from
one another, for clarity of illustration. Preferably, however, the
ends 28, 30 lie essentially along the same notional line.
[0068] First wall 10 includes a mouth 32 which preferably takes the
form of a slit formed in the first wall 10. The mouth 32 may
initially be in the form of a line of weakness, such as a line of
perforations, which is breached when required to form the mouth 32.
Most preferably, a closure flap 34 is provided on the first wall
10. The closure flap 34 extends across substantially the whole
width of first wall 10 and so lies over, and closes, the mouth 32.
The closure flap 34 is affixed to the first wall 10 in region 36
preferably by a suitable adhesive. The adhesive may be permanent so
that the closure flap 34 and the first wall are not separable in
region 36. The closure flap 34 is also attached to the first wall
10 in region 38. Region 38 is such that the closure flap 34 may be
peeled away from the first wall 10 across the region 38 without
substantially or significantly damaging the first wall 10. More
especially, it is important that the bond in the region 38 (whether
adhesive or otherwise) between the closure flap 34 and the first
wall 10 is such that the first wall 10 and the closure flap 34 can
be separated from one another without generating shards or pieces
of plastic which may subsequently contaminate, or have the
potential to contaminate, the contents of the bag section 4. Region
38 may be a welded or heat sealed region but is most preferably at
least one region of peelable adhesive. It Is most preferable that
the region 38 extends from one side edge 20 to the other side edge
20 without interruption. In the illustrated embodiment, region 38
comprises a single line of peelable adhesive. In alternative
constructions, a plurality, especially two or three, lines of
peelable adhesive may be provided. A corresponding region of
peelable adhesive (not illustrated) may be provided on the opposite
side of the mouth 32 from region 38. A line of weakness 40 is
provided at one side of the closure flap 34 and a corresponding
line of weakness (not illustrated) is provided at the other side of
the closure flap. For access to the mouth 32, the closure flap 34
is torn along the lines of weakness 40 and peeled back through the
region 38 to reveal the mouth 32. Numerous alternative
constructions for the lines of weakness 40 are possible. For
example, the lines of weakness could be curved or at an angle with
respect to the side edges 20, or a single line of weakness 40 in
the form of an arc extending from the leading edge 34a of the
closure flap 34 above the region 38 and the mouth 32 and returning
to the leading edge 34a at the other side of the closure flap
34.
[0069] Where the first and second walls are separably (rather than
permanently) attached to one another, or separably attached to the
bag section, the closure flap may be omitted and, if the closure
flaps 34 is present, the mouth 32 may be omitted. In preferred
variations, both the closure flap 34 and mouth 32 are present.
[0070] In some preferred constructions of the bags according to
this embodiment of the invention, the bag section 14 is initially
attached (e.g. adhered) to the cover section 4 with an adhesion
sufficient to maintain the desired relative positions of the
sections 4, 14 prior to the heat sealing step described below by
which the bag section is joined to the cover section in the
closeable region. This adhesion, if present, must be sufficient to
maintain the relative positions of the bag section 14 and cover
section 4, but not sufficient to prevent easy separation of the
sections 4, 14 when required. Thus, for example, an external face
of the third wall 16 may be provided with a line of adhesive
adjacent the open end 30 by means of which the third wall is
adhered to an internal face of the first wall 10. Similarly, an
external face of the fourth wall 18 may be provided with a line of
adhesive adjacent the open end 30 by means of which the fourth wall
18 is adhered to an internal face of the second wall 12.
[0071] The bags of this embodiment of the invention are provided
with a closeable region 42 which can extend from above the mouth 32
towards the ends 28, 30 of the cover section and bag section 4, 14.
The actual extent of the closeable region 42 can be determined in
accordance with the manufacturer's wishes but it is essential in
this embodiment that the closeable region 42 does not encompass the
mouth 32. Within the closeable region, heat sealing means can be
applied to the bag whereby the internal faces of the third and
fourth walls 16, 18 are heat sealed together. In this way the bag
section 14 is sealed and closed after having been filled with
contents. This heat sealing step may also seal together any
portions of the first and second walls 10, 12 which extend beyond
the upper edge of the bag section 14.
[0072] The heat sealing step for sealing together the third and
fourth walls 16, 18 is also effective in securely attaching the
cover section 4 to the bag section 14. This is achieved in
accordance with the invention in such a way that the sections 4, 14
are sufficiently securely attached to prevent them from being
separated in normal transport and handling but not so securely that
the sections 4, 14 cannot be separated manually when desired.
[0073] It would normally be expected that simple application of a
heat seal which joins the first wall 10 to the third wall 16 and
the second wall 12 to the fourth wall 18 will result in a joint
between the respective walls of a strength such that the cover
portion 4 is not easily separable when required from the bag
section 14. In this respect, the choice of materials for the first,
second, third and fourth walls 10, 12, 16, 18 can affect the
strength of the heat seal and it is possible, for example, to
achieve a heat seal of the desired strength by selecting materials
respectively for the first and third and for the second and fourth
walls whose compatibility for heat sealing is poor. In this way,
the strength of the resultant heat seal is not too great and so the
cover section 4 can be separated from the bag section 14 when
required. The choice of materials in this respect is within the
skill and knowledge of the person skilled in the art.
[0074] However, in preferred embodiments of the invention, at least
one of the first, second, third and fourth walls, 10, 12, 16, 18 is
provided, at least in the closeable region, with a treated area 44
which interferes with the heat seal so limiting or reducing its
strength to an extent that the first and bag sections 4, 14 can be
separated when required. The treated area 44 is preferably provided
on an internal surface of both the first and second walls 10, 12 or
on an external surface facing the internal surface of the walls 10,
12, such as both external surfaces of the third and fourth walls
16, 18.
[0075] The treated area 44 can take any reasonable form for
appropriately weakening the heat seal in the closeable region (that
is, the heat seal other than that between the internal surfaces of
the third and fourth walls) provided that other features of the bag
are not adversely affected. For example, the first and second walls
10, 12 or the third and fourth walls 16, 18 may be provided with an
embossed region which interferes with the heat seal.
[0076] In a particularly preferred form of the invention the
treated area extends over the whole of the internal surfaces of the
first and second walls 10,12. Of course, the effect of the treated
area is apparent only in those areas which are subsequently heat
sealed.
[0077] Most preferably, however, the treated area 44 is a coated or
printed area. The treated area 44 is preferably not printed across
the whole area. Rather, the treated area preferably comprises
printed regions 44A and non-printed regions 44B (FIG. 5). The
relative areas of the printed and non-printed regions will
determine the strength of the resultant heat seal, that is, in
general terms, the greater the area of the printed regions, the
weaker will be the heat seal. Preferably, the treated area
comprises alternate printed and non-printed regions, for example in
the form of alternating stripes which may be arranged, for example,
diagonally with respect to side edges 20. The relative areas of the
printed and non-printed regions in any given bag of the invention
can be determined by simple experiment by the person of ordinary
skill in the art, in order to achieve an effective bond strength of
the heat seal. Typically, relatively wide printed regions will
alternate in the treated area 44 with relatively narrow non-printed
regions.
[0078] In use of the bags according to the invention, the bag
section 14 is first filled with the product to be contained in the
bag 2 through the open end 30. When the desired amount of product
has been placed in the bag section 14, the bag is closed by heat
sealing in the closeable region 42. That is, the heat sealing In
the closeable region 42 seals together the third and fourth walls
16, 18 whereby the product is sealed within, and prevented from
escaping from, the bag section 14. In the same sealing step, the
cover section and bag section 4, 14 are joined together with a heat
seal, in the closeable region 42, between the internal surfaces of
the first and second walls 10, 12 and external surfaces of the bag
section 14. It is noted that this heat sealing may be in addition
to an initial adhesion of the cover section 4 and bag section 14
sufficient to retain the sections together before and during
filling. The heat sealing in the closeable region 42 may, for
example, form a joint between the first and third walls 10, 16 and
the second and fourth walls 12, 16. After the heat sealing step,
the bag and its contents may be stored or transported as required.
When access is required to the contents of the bag, the mouth 32 in
the first wall 10 is opened. In accordance with the illustrated
embodiment, the closure flap 34 is peeled back through the region
38 by tearing along the lines of weakness 40 to reveal the mouth
32. The cover section 4 and bag section 14 are then separated by
breaking apart the heat seal in the closeable region 42 (which
includes a treated area 44) between the sections 4, 14. The bag
section 14 may then be withdrawn through the mouth 32 of the cover
section 4. Alternatively, depending on the extent of the provision
of the treated area(s) 44, the first and second walls may simply be
peeled away from the bag section 14. At this stage, the heat seal
between the third and fourth walls of the bag section remains
intact so that the contents continue to be retained in the bag
section 14. The bag section 14 may then be opened as desired to
access the contents.
[0079] In a much preferred embodiment the bag section 14 is also
provided with a mouth 132 and a closure flap 134 overlying and
closing the mouth 132. The construction of the closure flap 134 is
essentially the same as that of the closure flap 34. Thus, the
closure flap 134 is preferably permanently adhered to the bag
section 14 in region 136 and is peelably adhered to the bag section
14 in region 138. The closure flap 134 is also provided with lines
of weakness 140. Thus, after separation of the cover section 4 and
the bag section 14, such as by extraction of the bag section 14
from the cover section 4 through mouth 32, the bag section 14 can
be opened by tearing the closure flap 134 along the lines of
weakness 140 and peeling back through the peelably attached region
138 to reveal the mouth 132, through which the contents of the bag
section 14 may be dispensed. As with the mouth 32, the mouth 132
may initially be formed as a line of weakness such as a perforation
which is breached to form the open mouth 132.
[0080] The closure flap 134 and mouth 132 may preferably be
disposed on the fourth wall of the bag section, that is so that the
closure flap 134 and mouth 132 are arranged on the wall (18) of the
bag section which is distant from the mouth 32 and closure flap 34.
In this construction, a treated area 144 may be formed on a region
of the closure flap 134 on its face juxtaposed with the second wall
12. Such a treated area 144 on the closure flap 134 is preferably
in addition to the treated area 44 formed on the third wall 16 in
juxtaposition to the first wall 10. However, a treated area on the
closure flap 134 is not needed if the internal surface of the
second wall 12 has a corresponding treated area 44.
[0081] As can be seen from FIG. 2A, the closeable region in one
preferred construction of the bag according to this embodiment of
the invention encompasses the third and fourth walls 16, 18, the
first and second walls 10, 12 and the first and second closure
flaps 34, 134.
[0082] FIGS. 2A, 2B and 3 illustrate the mouth 132 and closure flap
134 at the top portion of the bag, approximately adjacent the open
end 30. This construction is preferred but not essential. The mouth
132 may be formed in any part of the third or fourth wall 16, 18
other than the closeable region, and the closure flap 134 is
positioned accordingly on the third or fourth wall 16, 18 so that
the mouth 132 is closed. In these constructions, the closure flap
134 may be placed entirely outside the closeable region 42.
[0083] In a preferred construction, as shown in FIG. 2B, the fourth
wall 18 is made shorter than the third wall 16 so that the mouth
132 is defined by an upper end edge of the fourth wall 18. The
closure flap is then peelably attached to the fourth wall 18 in
region 138 only with the remainder of the closure flap 134 directly
overlying the internal face of the third wall 16. In effect, the
upper portion of the closure flap becomes an extension of the
fourth wall 18. Permanently attached region 136 is omitted. In this
construction the heat seal which closes the bag section to retain
the contents therein is made between the third wall 16 and the
closure flap 134, but not with any part of the fourth wall 18.
References herein to forming a heat seal between the third and
fourth walls 16, 18 should be construed accordingly to include this
construction, unless the context specifically requires otherwise.
Likewise in this construction there is no heat seal in the
closeable region 42 between the second and fourth walls 12, 18.
Since the closure flap 134 acts as an extension of the fourth wall
18, the union in the closeable region is between an inner face of
the second wall 18 and an external face of the closure flap 134.
Again, reference to a union (heat seal etc) between an inner face
of the first or second wall and an external face of a bag section
wall should be construed to include the option of a closure flap of
the bag section acting as an extension of the relevant bag section
wall.
[0084] A similar construction is possible with respect to the
closure flap 34 and the first wall 10 in that the first wall 10 may
be made shorter than the second wall 12 so that the closure flap 34
is adhered to the first wall 10 only in region 38 with the upper
part of the closure flap 34 directly overlying the third wall 16.
The upper part of the closure flap 34 then acts in effect as an
extension of the first wall 10 and is heat sealed in use to the
treated area 44 on the third wall 16, in the closeable region 42.
References to portions of the first wall in the closeable region
and/or the interaction of the first wall with the treated area
should be construed accordingly.
[0085] FIG. 4 illustrates an alternative construction of the
closure flap which may be applied to either of the closure flaps 34
and 134 (and to closure flaps 334 and 434 described below). This
construction achieves the same result as the construction
illustrated in FIGS. 1 to 3 but does not require a peelable
adhesive. In the construction of FIG. 4 the closure flap 234
includes a line of weakness 240 extending in a curved line on
either side of the mouth 232. Other lines of weakness are possible
such as "V" or "U" shapes. An area 200 is thus bounded by the line
of weakness 240 and within this area the closure flap 234 is not
adhered at all to the underlying wall (10, 12, 16 or 18). Outside
the area 200, in area 202 the closure flap 234 is adhered, welded
or otherwise bonded to the underlying wall to form a closure over
the mouth 232. To this end, heat sealing or adhering of the closure
flap 234 around its marginal edges is shown at 204 in FIG. 4. The
relevant bag section 4, 14 may thus be opened by tearing the
closure flap 234 along the line of weakness 240 to reveal the mouth
232.
[0086] Referring now to FIGS. 6 to 8, the bag of the second
embodiment of the invention comprises a cover section 304 and a bag
section 314. The cover section 304 and the bag section 314 are most
preferably of substantially the same width, although in the
illustrated embodiment, the cover section 304 is longer than the
bag section 314. The cover section 304 comprises first and second
walls 310, 312 and the bag section 314 comprises third and fourth
walls 316, 318. The end 328 of the bag portion 314 is open (i.e.
the third and fourth walls 316, 318 are not joined together) to
allow the bag portion 314 to be filled. At the sides 320 and base
326 of the bag portion 314 the third and fourth walls 316, 318 are
permanently joined together, preferably by means of heat welding,
as indicated in regions 320A and 326A respectively. In regions 320A
at the sides of the bag 302 the respective first and second walls
310, 312 are separably attached to the underlying bag portion 314.
Similarly, at the upper end 328 of the bag 302, the first and
second walls 310, 312 are separably attached to the underlying bag
portion 314 in region 328A, extending across the whole width of the
bag 302. In regions 320B and 322A the first and second walls 310,
312 are attached to one another, preferably separably. In region
326A the first and second walls 310, 312 may be, but need not be,
separably attached to the bag portion 314. In these regions 320A,
320B, 322A, 328A the first and second walls 310, 312 are preferably
attached by heat welds.
[0087] The bag portion 314 is shown in FIGS. 6 and 7 as comprising
a third wall 316 which is shorter than fourth wall 318. The edge of
the third wall 316 is indicated at 316.dagger-dbl.. However, the
third and fourth walls 316, 318 could be the same length, as
indicated in FIG. 8.
[0088] In FIGS. 6 and 7, a closure flap 334 overlies the upper
portion of the third wall 316 and is attached to the third wall 316
by means of a band or line or peelable adhesive 338. The closure
flap 334 is in effect an extension of third wall 316 and is
separably attached to first wall 310 in region 328A. The closure
flap includes a line of weakness 340 (and a corresponding line of
weakness at the opposite side, not shown) along which the closure
flap 334 can be torn to expose the mouth 332 defined by upper edge
316.dagger-dbl. of third wall 316, whereby access is gained to the
contents of the bag portion 314.
[0089] The bag 302 includes a closeable region 342 between end 328
and the mouth 332 (but not including the mouth 332). In closeable
region 342, the third and fourth walls 316, 318 are, in use of the
bag, sealed closed after filling of the bag portion 314 with its
desired contents. This is most preferably achieved by means of heat
sealing. The closeable region 342 is functionally the same as
closeable region 42 of the first embodiment of the invention.
[0090] For the avoidance of doubt, in FIG. 6, area W shows the
complete bag including the first wall 310, in area X the first wall
310 is cut away revealing the closure flap 334, in area Y the
closure flap is cut away revealing the third wall 316 and the
fourth wall 318 and in area Z the third wall is cut away revealing
the second wall 312.
[0091] As mentioned above, the first and second walls 310, 312 of
the cover portion 304 are separably attached to the bag portion
314, so as to enclose the bag portion. In the most preferred
variations of the invention, the separability is achieved by
providing a treated area or treated areas 344 which interfere with
the strength of the union (preferably a heat seal) between the
respective first and second walls 310, 312 and the third and fourth
walls 316, 318 or closure flap 334. The treated areas 344 are most
preferably provided in the same way as the treated areas 44
according to the first aspect of the invention. Thus the treated
areas are preferably coated or printed areas. For example, printed
regions may be provided on the third and fourth walls 316, 318 and
the closure flap 334 in areas corresponding to (but preferably of
somewhat greater extent than) regions 320A and 328A, together with
an area corresponding to the closable region 342 and, optionally,
areas corresponding to areas 320B and 326A. In other words, the
treated areas 344 are provided in only those regions where the
first and second walls 310, 312 are attached to the third and
fourth walls 316, 318 and to the closure flap 334.
[0092] It is, however, more expedient in terms of the manufacture
of the bags, and much preferred, to provide the treated area 344
across the whole of the inner surfaces of the first and second
walls 310, 312 (that is, across the whole of the surfaces of the
first and second walls 310, 312 which oppose the bag portion 314).
This means that, during manufacture of the bags and subsequently
during heat sealing of the closeable region there is no uncertainty
as to whether the heat sealing which joins the various walls
together is, or is not, in a treated area 344. Of course, a treated
area 344 is never formed on the internal surfaces of the third and
fourth walls 316, 318 which define the interior of the bag portion.
Most preferably, where the first and second walls 310, 312 are
formed from a transparent material, the treated areas, especially
printed areas, are also substantially transparent.
[0093] In a preferred form of the bags of this embodiment of the
invention, the area 328A, preferably the areas 320A and optionally
the areas 320B and 322A may, during manufacture be made somewhat
wider than finally required. These areas may then be trimmed, such
as with an automatic knife or other cutting device to remove a
small excess of material. This then ensures that the bond between
the various walls and between the walls and the closure flap(s) in
these regions extends right to the very edge of the bag. This
ensures that no crevices, recesses, channels or the like are left
which might harbour foreign bodies or infectious agents (bacteria
etc.) which could contaminate the contents of the bag portion 314.
This is of especial importance in region 328A where the first wall
310, is joined respectively to the closure flap 334 (FIG. 7) or
third wall 316 (FIG. 8) and the second wall 312 is joined to the
fourth wall 318, as these regions are directly exposed to the
product as it is being filled into the bag portion 318.
[0094] A variation of the bag of this second aspect of the
invention is shown in FIG. 8 in which features corresponding or
similar to those of FIG. 7 are given like reference numbers and
features which differ are given reference numbers with the prefix
"4". In FIG. 8, an additional closure flap 434 is provided on an
outer wall (first wall 310 or second wall 312) of the bag 302. This
construction is especially desirable where, as indicated in the
preceding paragraph, the edges of the bag have been trimmed during
manufacture so that the bond between the various walls and closure
flaps extends right to the edge of the bag 302, most especially at
end 328. Because the various walls and closure flap(s) are bonded
right to the edge of the bag 302, it may be difficult for a user to
obtain purchase or grip on one of the first or second walls 310,
312 in order to separate the walls 310, 312 from the bag portion
314. The additional closure flap 434 allows such purchase or grip
easily to be provided in that, on tearing or peeling back of the
tearable or peelable portion of the closure flap 434, the user has
a substrate to grip while pulling the respective first and second
walls 310, 312 away from one another to separate them from the bag
section 314. In a further preferred variation, the wall lying below
the closure flap 434 (first wall 310 or second wall 312) may be
provided with a mouth 442 in the form of a slit, or more
preferably, in the form of a line of weakness which may be ruptured
as, or after, the closure flap 434 is peeled or torn back. When the
mouth 442 is opened the user is provided with an edge of the wall
(310 or 312) which can be gripped directly for pulling the walls
310, 312 away from one another.
[0095] In an alternative, but less preferred variation of the
invention one or both of the walls 310, 312 may be provided with a
gripping tab, loop or the like which a user can grasp for
separating the cover section 304 from the bag section 314.
[0096] As noted above, FIG. 8 shows a further variation in that the
walls 316, 318 of the bag section 314 are of equal length. The
mouth 432 for access to the interior of the bag section 314 is thus
formed as a slit in wall 316 which is closed by closure flap
334.
[0097] In use of the bags of this embodiment of the invention, the
baf is preferably manufactured by heat sealing the first and second
walls respectively to the third and fourth walls at their edges.
Because the first and second walls comprises a treated area across
the whole of their inner faces, the heat sealing of the walls
renders them separable when desired. The third and fourth walls are
also heat sealed at their edges, either contemporaneously with the
heat sealing of the first and second walls to the third and fourth
walls, or separately. In manufacture, no heat seal is formed
between the third and fourth walls at the top end 328 of the bag.
The bag portion 314 is then filed with the desired contents. A heat
seal is applied in the closeable region to join the third and
fourth walls together and so seal the contents within the bag
section. This heat seal also further joins the first and second
walls respectively to the third and fourth walls, the treated area
of the first and second walls rendering this joint separable. The
bag is then stored and/or transported as required. When accessis
required to the contents of the bag portion 314, the first and
second wall 310, 312 are peeled away from the bag portion, with the
assistance of the closure flap 434 if present. Access to the
contents of the bag portion 314 is gained by peeling or tearing
back the closure flap 334 and opening mouth 332 through which the
product Is dispensed.
[0098] Thus a particularly preferred plastic bag according to the
second embodiment of the invention comprises: [0099] i) a bag
section comprising third and fourth opposed walls joined at their
side and base edges and an open end by means of which the bag
section may be filled with contents; [0100] ii) a cover section
comprising first and second opposed walls which are substantially
co-extensive in width with the third and fourth walls, arranged to
enclose the bag section and attached to the third and fourth walls
at their side edges and upper edge; [0101] iii) a closeable mouth
defined in a wall of the bag section for access in use to the
interior of the bag section; [0102] iv) a closeable region,
distinct from the mouth, including an end portion of the cover
section and an end portion of the bag section proximate the open
end of the bag section, within which closeable region the bag
section may be sealed closed after filling; wherein [0103] (a) in
the closeable region, the internal faces of the respective first
and second walls are attachable to the adjacent external face of a
wall of the bag section and [0104] (b) the internal face of each of
the first and second walls is treated to provide alternating
printed and non-printed areas whereby the attachment of the first
and second walls to the bag section is such that the bag section is
separable in use from the cover section without compromising the
seal of the bag section in the closeable region.
[0105] The bag section may comprise a closure flap covering a
mouth, the mouth providing access to the interior of the bag
section. In this case, one of the first and second walls is
attached to an outer surface of the closure flap. Part of the
closure may also lie in the closable region.
[0106] In another variation of both the first and second
embodiments of the invention, the third and/or fourth walls may be
provided with a plurality of small holes 360 (FIG. 6), i.e.
pin-holes of diameter not more than about 1 mm, and preferably
substantially less. These holes are provided to allow air to escape
from the interior of the bag section. The size and number of the
holes is selected so that the air escapes gradually into the space
between the third and fourth walls (and where present, the closure
flap) and the first and second walls. The air then seeps or
gradually escapes out of that space to the exterior. In this way,
air is not retained in the bags of the invention when the filled
bags are stacked such as on a pallet. The product contained in the
bag is of course retained in the bag and does not substantially
pass through the pin-holes. By allowing the air to escape, the
filled bags can be stacked more stably and are less vulnerable to
bursting under the pressure generated by bags higher up a
stack.
[0107] In accordance with this aspect of the invention there is
provided a plastic bag comprising: [0108] i) an inner bag portion
defined by third and fourth walls joined at their edges and base
and having an open upper end; [0109] ii) a cover portion enclosing
the bag portion defined by first and second walls joined at their
edges and base, and [0110] iii) at least one region in which the
cover portion is joined to the bag portion the third and/or fourth
wall further comprising a plurality of pin-holes by means of which
air can gradually escape from the bag portion when filled with
contents into the space between the cover portion and the bag
portion.
[0111] Preferably the cover portion and bag portion are separably
joined to one another. In this respect, preferably at least one of
the walls, more preferably the first and second walls include a
treated region as discussed and defined above. Preferably also the
bag of this aspect of the invention comprises a closure portion of
the type defined and described above.
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