U.S. patent number 3,910,488 [Application Number 05/460,497] was granted by the patent office on 1975-10-07 for gusseted pinch bottom breakaway pouch bag.
This patent grant is currently assigned to St. Regis Paper Company. Invention is credited to John J. Goodrich.
United States Patent |
3,910,488 |
Goodrich |
* October 7, 1975 |
Gusseted pinch bottom breakaway pouch bag
Abstract
A bag of tubular form open at one end and closed at the other
end, comprising a plurality of contiguous plies of paper bonded
together adjacent each of said ends, and an innermost ply of heat
sealable plastic material lightly bonded adjacent said bag ends to
the contiguous paper ply for manual detachment therefrom, said bag
being longitudinally and reversely creased along diametrically
opposed portions to provide a pair of oppositely disposed gussets
interposed between front and rear wall portions, at least some of
the inner plies being stepped progressively upward with respect to
the outer ply in the front wall portion at the open bag end, at
least the outermost ply being stepped upwardly with respect to the
innermost ply in the rear wall portion at the open bag end to
provide an exposed overlap rear wall portion with respect to the
innermost ply of said front wall portion, at least portions of said
gussets terminating at said open bag end within said overlap to
provide exposed portions thereof, said overlap rear wall and
exposed gusset portions being coated with an adhesive at said open
bag end, the bag construction at said closed end being the reverse
of that at the open end said plastic ply being heat sealed to
closure adjacent said closed bag end, the bag closure at said end
being otherwise completed by coating the exposed overlapping rear
wall portion and exposed gusset portions with an adhesive and
folding over with said sealed end of said plastic ply and sealed to
closure against the opposite wall portion, said bonding together of
said paper plies at said end thereby imparting to said closure the
combined strength of all such plies, the open end of said bag being
adapted for heat sealing of said plastic ply and closure similarly
to that of said closed end and said bag when so closed at both ends
being sift and leak proof and resistant to insect penetration, and
being adapted for opening of said paper plies and removal of said
plastic ply intact.
Inventors: |
Goodrich; John J. (Pensacola,
FL) |
Assignee: |
St. Regis Paper Company (New
York, NY)
|
[*] Notice: |
The portion of the term of this patent
subsequent to April 30, 1991 has been disclaimed. |
Family
ID: |
26929315 |
Appl.
No.: |
05/460,497 |
Filed: |
April 12, 1974 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
|
|
235908 |
Mar 20, 1972 |
3807626 |
|
|
|
Current U.S.
Class: |
383/85; 383/111;
383/206 |
Current CPC
Class: |
B65D
31/02 (20130101); B65D 75/68 (20130101) |
Current International
Class: |
B65D
30/08 (20060101); B65D 75/52 (20060101); B65D
75/68 (20060101); B65D 033/02 () |
Field of
Search: |
;229/55,56,57,62,66 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Price; William I.
Assistant Examiner: Garbe; Stephen P.
Attorney, Agent or Firm: McElhannon, Esq.; Raymond J.
Parent Case Text
This application is a continuation-in-part of my copending
application Ser. No. 235,908 now Pat. No. 3,807,626 filed Mar. 20,
1972, and incorporates the same by reference herein.
Claims
I claim:
1. A bag of tubular form open at one end and closed at the other
end, comprising a plurality of contiguous plies of flexible sheet
material bonded together adjacent each of said ends, and an
innermost ply of heat sealable plastic material lightly bonded
adjacent said bag ends to the contiguous paper ply for manual
detachment therefrom, said bag being longitudinally and reversely
creased along diametrically opposed portions to provide a pair of
oppositely disposed gussets interposed between front and rear wall
portions, at least some of the inner plies being stepped
progressively upward with respect to the outer ply in the front
wall portion at the open bag end, at least the outermost ply being
stepped upwardly with respect to the innermost ply in the rear wall
portion at the open bag end to provide an exposed overlap rear wall
portion with respect to the innermost ply of said front wall
portion, at least portions of said gussets extending above said
front wall portion at said open bag end and terminating within said
overlap rear wall portion to provide exposed portions of said
gussets, said overlap rear wall and exposed gusset portions being
coated with a reactivatable adhesive at said open bag end, the bag
construction at said closed end being the reverse of that at the
open end, said plastic ply being heat sealed to closure adjacent
said closed end, the exposed overlapping rear wall portion and
exposed gusset portions thereat being folded over with said heat
sealed end of said plastic ply and sealed to closure against the
opposite wall portion, said bonding together of said paper plies at
said end thereby imparting to said closure the combined strength of
all such plies, the open end of said bag being adapted for heat
sealing of said plastic ply and closure similarly to that of said
closed end and said bag when so closed at both ends being sift and
leak proof, and resistant to insect penetration and being adapted
for opening of said paper plies and removal of said plastic ply
intact.
2. A bag of tubular form open at one end and closed at the other
end, comprising a plurality of outer contiguous plies of flexible
sheet material bonded together at each of said ends, but being
otherwise detached from one another, and an innermost ply of heat
sealable plastic material lightly bonded adjacent said bag ends to
the contiguous outer ply for manual detachment therefrom, said bag
being longitudinally and reversely creased along diametrically
opposed portions to provide a pair of oppositely disposed gussets
interposed between front and rear wall portions, at least some of
the inner plies being stepped progressively upward with respect to
the outermost ply in the front wall portion at the open bag end, at
least some of the outer plies being stepped progressively upward
with respect to the innermost ply in the rear wall portion at the
open bag end and said rear wall portion extending above said front
wall portion at said end to provide an exposed overlap rear wall
portion with respect to said front wall portion, at least the rear
portions of said gussets extending above said front wall portion at
said end and terminating within said overlap rear wall portion to
provide exposed portions of said gussets, said exposed rear wall
overlap portion and exposed gusset portions being coated with a
heat reactive adhesive in a dormant state at said open bag end, the
bag construction at said closed end being reverse of that at the
open end, said plastic ply being heat sealed to closure adjacent
said closed end, and the overlapping rear wall portion and exposed
gusset portions thereat being folded over with said sealed end at
said plastic ply and sealed to closure against the opposite wall
portion, said bonding together of said plies at said end thereby
imparting to said closure the combined strength of all said plies,
the open end of said bag being adapted for heat sealing of said
plastic ply and closure similarly to that of said closed end, and
said bag when so closed at both ends being sift and leak proof and
resistant to insect penetration, and being adapted for opening of
said paper plies and removal of said plastic ply intact.
3. A bag of tubular form open at one end and closed at the other
end, comprising a plurality of at least three outer plies of
flexible sheet material bonded together at said ends, respectively,
but being otherwise detached from one another, and an innermost ply
of heat sealable plastic material lightly bonded adjacent said bag
ends to the contiguous outer ply for manual detachment therefrom,
said bag being longitudinally and reversely creased along
diametrically opposed portions to provide a pair of oppositely
disposed gussets interposed between front and rear wall portions,
at least some inner plies being stepped progressively upward with
respect to the outer ply in the front wall portion at the open bag
end, at least some of said plies being stepped progressively upward
with respect to the innermost ply in the rear wall portion at said
bag end said rear wall portion extending above said front wall
portion at said end to provide an exposed overlap rear wall portion
with respect to said front wall portion, said gussets extending
above said front wall portion and terminating at said open bag end
within said overlap rear wall portion, and the rear portions of
said gussets being stepped upwardly with respect to the front
portions thereof to provide exposed front and rear gusset portions
thereof, said exposed overlap rear wall portion and said exposed
gusset portions being coated with a heat reactivatable adhesive in
a dormant state at said open bag end, the bag construction at said
closed end being the reverse of that at the open end, said plastic
ply being heat sealed to closure adjacent said closed end, and the
exposed overlapping rear wall portion and exposed gusset portions
thereat being folded over with said sealed end of said plastic ply
and sealed against the opposite wall portion, said bonding together
of said plies at said end thereby imparting to said closure the
combined strength of all said plies, the open end of said bag being
adapted for heat sealing of said plastic ply and closure similarly
to that of said closed end, said bag when so closed at both ends
being sift proof and leak proof throughout and resistant to insect
penetration.
4. A bag of tubular form comprising a plurality of at least three
outer plies of flexible sheet material bonded together at each end
thereof, and an innermost ply of heat sealable plastic material
lightly bonded adjacent said bag ends to the contiguous outer ply
for manual detachment therefrom, said bag having a front surface
and an oppositely disposed rear surface extending beyond and
overlapping said front surface at said open end of said tube when
said bag is in its assembled condition, said bag being
longitudinally and reversely creased along diametrically opposed
portions to provide a pair of oppositely disposed gussets
interposed between said front and rear surfaces, each of said
gussets having an exposed front portion and an exposed stepped rear
portion adapted to overlap said front portion within the overlapped
area of said front and rear surfaces at said one end of the tube
when said bag is in its assembled condition, at least some of the
bag plies being stepped one beyond another at said end in each of
said front and rear surfaces to provide exposed portions thereof,
at least some of said bag plies being stepped one beyond another in
each of said front and rear gusset portions at said one end of said
tube, a bonding agent in a dormant state applied to said exposed
gusset portions and over said overlap portion of said rear surface
at said one end of said bag, the bag construction at said closed
end being the reverse of that at said open end, said plastic ply
being heat sealed to closure adjacent said closed end, and the
overlap rear surface portion and exposed gusset portions thereat
being folded over with said sealed end of said plastic ply and
sealed to closure against the opposite surface portion, said
bonding together of said plies thereat thereby imparting to said
closure the combined strength of all said plies, the opposite end
of said bag being the reverse of said one end and adapted for heat
sealing of said plastic ply and closure similarly to that of said
closed end, and said bag when so closed at both ends being leak
proof, sift proof and impervious to insect penetration
throughout.
5. A bag of tubular form open at one end and closed at the other
end, comprising a plurality of at least three contiguous plies of
paper bonded together adjacent said ends, and an innermost ply of
heat sealable plastic material lightly bonded adjacent said bag
ends to the contiguous paper ply for manual detachment therefrom,
said bag being longitudinally and reversely creased along
diametrically opposed portions to provide a pair of oppositely
disposed gussets interposed between front and rear wall portions,
said rear wall portion being stepped upwardly at said open bag end
beyond said front wall portion to provide an exposed overlap rear
wall portion thereof, at least some of said plies being
progressively stepped in each of said front and rear wall portions
at said end of said bag, said gussets extending at said open bag
end beyond said front wall portion and terminating within said rear
wall overlap portion, to provide exposed front portions and exposed
stepped up rear portions of said gussets, said exposed overlap rear
wall portion and said exposed gusset portions being coated with a
reactivatable adhesive, said closed bag end being the reverse of
said open bag end, said plastic ply being heat sealed to closure
adjacent said closed end, and the overlapping portion thereat being
folded over with said sealed end of said plastic ply and sealed to
closure against the opposite wall portion, said bonding together of
said plies at said end thereby imparting to said closure the
combined strength of all said plies, the open end of said bag being
adapted for heat sealing of said plastic ply and closure similarly
to that of said closed end, and said bag when so closed at both
ends being sift and leak proof and resistant to insect penetration,
and being adapted for opening of said paper plies and removal of
said plastic ply intact.
Description
This invention pertains to improvements in multi-wall bags of the
gusseted and so called pinch bottom, open mouth type and the
production thereof, and to methods of filling and emptying the same
under sterile conditions.
In bags of this construction as heretofore produced, a plurality of
plies of flexible sheet material, such as paper, are laminated to
one another in superimposed relation and formed into a tube having
gusseted sidewalls interposed between front and back walls one of
which overlaps the other at each bag end, one overlapping end in
the bag as manufactured, being folded over and sealed against the
opposite wall to provide an open-ended bag ready for filling,
usually with a bulk, granular or powdery material, whereupon the
opposite overlapping end is similarly folded over and sealed
against the opposite wall thereby to seal the packaged material
within the bag enclosure thus formed. Also in such bags as herefore
produced, the innermost ply is sometimes provided with a moisture
impervious plastic coating, or an innermost ply of plastic
material, which is permanently laminated to the innermost ply.
All such conventional bag constructions are objectionable for the
packaging of comestibles, such as dry powdered milk, eggs or the
like, in that during handling and shipment the bag exteriors become
highly contaminated with dust, bacteria and other contaminating
substances, to the extent that it becomes extremely difficult if
not impossible to prevent contamination of the packaged material
when the bag is opened to discharge the contents.
In an effort to prevent such contamination, one practice has
consisted in the manual insertion into an open ended paper bag of a
separately produced plastic pouch, and then after the pouch within
the bag is filled, the pouch itself is manually tied closed at its
open end and pushed down into the bag so that it does not interfere
with closure of the bag itself, usually by sewing. This practice is
objectionable in that it requires that the bag and pouch components
be separately produced and the components manually assembled, which
is unduly expensive. Also the manual tying of the pouch when filled
and subsequent closure of the bag proper retards the closure
operations. In addition the manual handling of the plastic pouch in
the bag and pouch assembly and tying operations as well as the
subsequent untying to discharge the contents, are sources of
potential contamination.
The present invention eliminates these highly objectional features
of conventional bag constructions, in the provision of a
multi-wall, gusseted bag having an innermost bag ply of a heat
sealable plastic material, such as polyethylene, which in process
of bag manufacture on a bag tuber is only lightly adhered to the
contiguous paper ply, as by means of a pressure sensitive adhesive,
for manual detachment therefrom and which is heat sealed
transversely of the bag at the closed end, the bag closure at said
end being otherwise completed by folding over said end with said
heat sealed end of said plastic ply and sealing against the
opposite wall. Also when the bag is filled with a comestible or the
like, the opposite end of the plastic ply is closed by heat sealing
prior to folding over said end with said heat sealed end of said
plastic ply, and sealing against the opposite wall at said end. The
plastic ply is of such length as to be included in the sealed bag
end closures provided by the outermost plies. The bag may thus be
opened in the outermost plies leaving intact the plastic ply and
therein packaged contents. And since the plastic ply is only
lightly adhered to the contiguous ply, the outer plies may be torn
or cut away and peeled off of the plastic ply without rupture
thereof for removal of a thus completely sealed and impervious
plastic ply container of the packaged material. For removal of the
packaged contents without contamination, the exterior of this
plastic container may be sterilized and the container slit and its
contents discharged under wholly sterile conditions in a sterile
atmosphere.
In bag constructions according to the invention containing three or
more outer or paper plies, at least some of the plies exterior to
the innermost paper ply are preferably stepped successively in both
directions at the bag ends with respect to the innermost ply, to
provide at each bag end a stepped up overlap portion which may be
folded over with the innermost ply and adhesively bonded to the
opposite bag surface. This greatly increases the overall bonding
action at the bag ends and thereby enhances the strength of the bag
closures. The gussets may also be stepped up at the bag ends with
respect to the innermost ply, with the front and back panel
portions thereof either flush cut, or with the back panel portions
stepped up with respect to the front panel portions. Also at least
some of the bag plies may additionally be stepped up in the gusset
portions. All such modifications increase the bonding strength of
the bag closures upon folding over the overlapping bag ends and
sealing against the opposite bag wall portions.
The invention in other of its aspects comprises methods of filling
and emptying bags of the constructions above described in a manner
such that the bags may be filled with a material to be packaged and
completely sealed within the plastic ply prior to closure of the
open bag end, and the bag thereafter opened only in the outer plies
and the plastic ply with its sealed in contents thence removed
intact.
Having thus described the invention in its broader aspects
reference will now be had for a detailed description of the above
and other aspects to the accompanying drawings wherein:
FIG. 1 is a perspective view of a bag constructed in accordance
with one embodiment of the invention, and FIG. 1a a similar
fragmentary view of a further embodiment.
FIGS. 2 and 3 are longitudinal and transverse sections of FIG. 1
showing the constructional details.
FIG. 4 is a view similar to FIG. 2 but showing the bag prior to
effecting the bottom bag closure.
FIG. 4a is a fragmentary sectional view of the lower end of FIG. 4
showing a step in the bag closure operation.
FIGS. 5-7 inc. illustrate a method of producing bags according to
the invention, wherein FIG. 5 is a plan view of a web assembly for
producing the bags as blanks shown in plan view in FIG. 6, while
FIG. 7 is a plan view of a bag as produced from the bag blank of
FIG. 6.
FIGS. 8-11 inc. are views illustrating closure of the upper end of
the bag of FIGS. 1-3, after it is filled with material to be
packaged, wherein FIG. 10 is a view in elevation illustrating the
method and apparatus for sealing the upper end of the bag closed in
successive steps, while FIGS. 8, 9 and 11 are fragmentary sectional
views of FIG. 10 as taken at 8--8, 11--11 and 9--9 thereof,
respectively.
FIGS. 12-18 inc. are perspective views of the steps of opening the
filled and closed bag of FIG. 10, in such manner as to recover the
sealed inner plastic ply and therein packaged contents without
opening said ply.
Referring to FIGS. 1-4, the bag comprises an innermost ply 10 of a
heat sealable thermoplastic material, and four outer plies 11-14
inc., made preferably of heavy kraft paper, although other suitable
flexible sheet stock may be employed. The bag is gusseted along
oppositely disposed sidewalls, as at 15, 16, interposed being
relatively wide front and rear walls 17, 18.
The bag as manufactured is open at the top as shown and closed at
the bottom with a pinch bottom closure as at 19, produced as
described below. The paper plies 11-14 inc. are securely bonded to
one another at the top and base of the bag as described below,
while the plastic ply 10 is only lightly adhered to the contiguous
paper ply adjacent the top and base of the bag and blank, as
described below.
As best shown in FIG. 1, at the open bag end, the plastic and
contiguous paper plies 10, 11 are preferably substantially flush
cut, and the outer plies 12-14 preferably stepped successively
downward with respect thereto as shown. In the back wall 18, the
outer plies 12-14 are stepped as a group considerably upward with
respect to plies 10, 11, to provide an overlap 19 of the back wall
with respect to all plies of the front wall. In addition the outer
plies 12-14 are preferably stepped successively upward with respect
to each other as shown. Various upper terminations of the gussets
15, 16 may be employed, one embodiment of which is shown in FIG. 1
and another in FIG. 1a.
In FIG. 1, the front gusset panels, as at 21, are flush cut in all
plies substantially coincident with plies 10, 11; while in the back
gusset panels, as at 22, plies 12-14 are stepped up with respect to
all plies of the front gusset panels, as shown, and ply 12 is
additionally stepped up with respect to plies 13, 14, as shown.
In FIG. 1a, the ply stepping in the front and back walls is the
same as in FIG. 1a. In the gussets, however, plies 12-14 inc. are
stepped up with respect to plies 10, 11 in the front gusset panels
21, and plies 12-14 are further stepped up in the back gusset
panels 22, with respect to these plies in the front gusset panels,
in addition to which, ply 12 is further stepped up with respect to
plies 13, 14 in the back gusset panels.
The ply steppings in the front and back walls and the gusset and
gusset ply steppings shown in FIGS. 1 and 1a are merely
illustrative of the many embodiments that may be employed in
accordance with the invention, as encompassed by the appended
claims.
As shown in FIG. 4, the bottom of the bag of FIG. 1 is
complementary to or the reverse of that at the top.
Closure at the base of the bag to provide the pinch bottom closure
19, FIG. 1, is accomplished in two steps. The first step consists
referring to FIG. 4a, in applying heat and pressure between the
opposite walls of the blank adjacent the lower end, as by means of
hot compression rolls or bars as at 31, 32. This heat seals the
oppositely disposed wall portions of the thermoplastic ply to each
other as at 33, thus to provide a sealed closure of the ply at the
bottom of the bag. A thermoplastic adhesive is then applied to the
stepped end portions as at 34, FIG. 4, and the bag end folded over
at the "fold" line and sealed against the opposite wall of the bag
as shown in FIG. 2, and then compressed between compression rolls
as at 35, 36, FIG. 2.
In order to provide for opening the bag as described below, a rip
cord or tear string 37, as interposed as shown in FIG. 2, between
the outer paper plies 12-14 inc., and the inner plies 10, 11, upon
folding over and completing the bag closure in the manner above
described.
Referring now to FIGS. 4 and 5, the bags of the invention may be
quantity produced from superimposed webs 10-14 inc. of the plastic
and paper plies. The individual webs are transversely perforated as
at bag length intervals, as at 40 and 41, to impart the requisite
end configurations to the blanks as above described. These
perforations are for purposes of subsequently separating the web
stock into successive bag blanks, as at 42, 43, 44. As shown in the
drawing the perforations at one end of a blank, as at 40, are
complementary to those at the opposite end, as at 41, to prevent
waste of materials.
The plastic ply 10 is lightly adhered to the contiguous paper ply
11, adjacent the opposite ends of each blank, as at 45, 46. For
this purpose a pressure sensitive adhesive is preferably employed
such as an acrylic latex adhesive. The paper plies are permanently
laminated to one another at the bag ends by means of glue applied
between them over the areas 47, 48. The webs 10-14 inc. are
successively stepped transversely of their lengths, as at 49, to
provide longitudinally extending overlap portions to the paper webs
11-14 inc. to which glue is applied, as at 50, in order that the
web assembly may be formed into a tube by folding over the stepped
overlap portion 49 onto the oppositely stepped portions 51, and
adhering while meantime heat sealing the overlapped portions of the
plastic ply 10. During the tube forming operation, the web assembly
is reversely creased along the lines indicated at 52, 53, to form
the oppositely disposed gussets, as at 15, 16, in the resultant
tubular blank of FIG. 6. A hot melt adhesive is applied to exposed
overlap and gusset portions at the top and base of the bag blank as
at 23, 34, FIG. 4. The blank is closed at the base in the manner
above described with reference to FIGS. 4a and 2 to produce the
completed bag as shown in FIG. 7.
Referring now to FIGS. 8-11 inc., the open end of a bag 52 after
filling with material to be packaged, as at 53, is closed as
follows. Referring to FIG. 8, the first step consists in
compressing the opposed upper ends of the bag between hot pressure
rolls, as at 53, 54, to heat seal the upper ends of the plastic ply
55 to one another, as at 56. A hot air blast 57a is next applied to
heat-activate the thermoplastic adhesive 57 applied to the
overlapping portion 58, of the outer plies. The next step as shown
in FIG. 9 consists in folding over the bag end along the upper fold
line of FIG. 2, and passing thence between compressing rolls, as at
62, 63.
The above sequence of operations is rapidly carried out with the
mechanism of FIG. 10, wherein the filled bag 52 is transported on a
travelling belt 65, with its open end passing first between the
series of the hot pressure rolls 53, 54, for heat sealing to
closure the upper ends of the plastic inner ply, thence past the
hot air blast 57a, for reactivating the thermoplastic bonding agent
57, FIG. 8, thence under the folding device 60a, for folding the
bag end over onto the opposite bag surface, and thence between the
series of pressure rolls 62, 63, for completing the bag closure, as
at 67.
Referring to FIGS. 10 and 11, the open bag ends are rapidly closed
by placing the open ended bags on a travelling belt 65 when they
are transported between hot pressure rolls as at 53, for heat
sealing the plastic ply, thence past a hot air blast 57a for
reactivating the thermoplastic adhesive, thence under an end
folding device 60a, and thence between pressure rolls as at 63 for
sealing closed.
Referring now to FIGS. 12-18 inc., in order to remove from a bag 52
filled with a packaged material and sealed closed top and bottom as
in FIG. 11, the thermoplastic ply and therein sealed packaged
contents without rupturing said ply, the bag is opened in the outer
plies only, by pulling on the tear cord 37 as in FIG. 12, thereby
to expose as in FIG. 13, the upper sealed end 56 of the plastic ply
55. Since as above pointed out, the plastic ply is only lightly
adhered to the contiguous paper ply, all paper plies may now be
torn away from the plastic ply in the manner illustrated at 71, 72,
in FIGS. 14-17 inc. and the unruptured plastic ply 55 as filled
with the packaged contents, thus obtained intact, as shown in FIG.
18.
The heat sealable thermoplastic inner ply in bags of the invention
may be made of various materials, such for example as polyolefines
such as polyethylene and polypropylene, polyamides such as nylon
and polyesters such as polyalkylene derivatives of polycarboxylic
acids especially polyethylene terephthlite.
Reverting to FIGS. 2 and 5, the bonding together of the paper plies
12-14 inc. at the top and base of the bag thereby imparts to the
bag closure at each end the combined strength of all said plies by
reason of the integration of the plies thereat into a single ply of
the thickness of all said plies. It will be noted with reference to
FIG. 2 that in effecting the bag closure at the lower bag end, the
plastic inner ply 10 and contiguous paper ply 11, are folded over
as at 19a with the remaining outer plies for effecting the
closure.
The bag of the invention as heat sealed to closure in the plastic
ply at both bag ends and as further sealed to closure in the paper
plies at both bag ends, provides a sift proof and leak proof bag
throughout, and one which is resistant throughout to insect
penetration.
* * * * *