Note: Descriptions are shown in the official language in which they were submitted.
210~8~
Back~round and Su~mary of Invention
The invention pertains to a bag for the packaging of products
or commodities of the type having a sealed inner pou~h within a
multiple ply enclosing bag, and methods for making the bag, and for
filling and sealing the bag.
More particularly, the invention is directed toward an
improvement in a multiwall bag of the type formed from a tubular
flat blank.
The invention i5 also directed to the type of product package
that includes a standard pinch bottom for the outer multiple plies
at the bottom end of the bag. In this type o~ bag the commodity-
holding pouch is formed from an inner plastic ply that is heat
sealed at the pinch closure of the outer enclosing bag and open at
the opposite end for receipt of a product to be packaged~ Upon
filling the bag to a desired amount, the inner plastic ply is heat
sealed to close the open end and thereby create a sealed pouch
which may remain detachably bonded to the top end of the outer
plies or optionally might be severed to separate the plastic pouch
from the top end of the outer plies. In this regard the invention
is further directed toward those product bags wherein the multiple
outer plies are subsequently folded and bonded together at the top
cut following the heat sealing of the plastic ply.
The invention further provides for an improvement in multiwall
type bags as described, which utilize an adhesive bonding, or
equivalent, of the inner plastic ply to the innermost ply of the
outer plies, wherein the outer plies comprise a plurality of
contiguous overlying non-heat sealable plies bonded together.
The present invention is an improvement in the packaging arts
which have heretofore evolved, such as that disclosed in U.S.
Patent No. 4,088,264, entitled "Multiwall Pouch Bags for Detached
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Packaging of Commodities", issued May 9, 1978 to Vogt. In this
patent, open ended, pinch bottom, multiwall bags are disclosed as
having an inner ply of heat sealable plastic material, such as
polyethylene, and one or more outer plies of a non-heat sealable
material, such as paper or equivalent. The plastic ply is bonded
at both bag ends to khe contiguous outer plies during bag
manufacturing and heat sealed and severed at the lower heat sealed
zone during the bag bottoming operation. At the top opening of the
bag, following the introduction of a product, commodity, or items,
the plastic ply is heat sealed to closure and must be severed along
the upper heat seal zone prior to closure of the outer plies. The
result is a fully closed plastic bag inside of the ~ully closed
paper bag. The problems that exist with this design are that when
the unfilled bag is standing ready to be filled, the inner plastic
bag is shorter in length than the enclosing outer paper bag. As
the commodity is discharged or placed into the bag during the
filling process there often are uneven and excessive pressures
exerted on the lower plastic seal creating a potential for seal
failure or pinholing along the bottom heat seal zone. Also, a
slight collapsing of the outer bag can be caused as the weight from
the commodity forces the upper portion of the bag downward, thus
creating problems with the integrity of the upper closure.
The present invention greatly reduces the pos~ibility of
bottom plastic seal failure, or bag collapse during the bag ~illing
process, and offers significant improvement over previously known
techn;ques and bag constructions.
BRIEF BUMMARY OF THE lNV ~_. lON
The invention solves the foregoing problems in multiwall bag
constructions and methods o~ making them by providing an inner
plastic bag that is as long as the outer paper bag during the
~illing process. The bottom plastic s~al is folded (wrapped)
around the pinch bottom fold line at the bag bottom during the bag
bottoming operation, but is not adhered or bonded to the contiguous
21~8l~J
outer plies. Instead, it is loosely, or freely folded with the
outer contiguous plies which provides for partial restraint thereat
duriny filling by virtue of staying in place at the bottom pinch
closure. Therefore, the lower plastic heat seal is protected from
excessive pressures during the bag filling process. Likewise,
because the inner plastic pouch is as long as the outer paper bag,
the probability of collapsing the upper portion of the bag during
the bag filling process has been reduced, giving greater insurance
of a proper closure of the open top bag end once the product or
commodity has been introduced.
BRI15F DE8CRIPTION OF T}IE: DRAWINGB
~'
The invention will be further describsd in detail with
reference to the accompanying drawings wherein like reference
numerals throughout refer to the same elements and wherein:
Fig. 1 is a perspective, partially broken away, view of the
multiply bag in accordance with the invention ready to be filled by
the packer with a commodity or the like;
Fig. 2 is a horizontal cross section of the bag shown in Fig.
1 taken along the line 2-2 looking in the direction of the arrows;
Fig. 3 is a vertical cross sectional view of the bag as shown
in Fig. 1 taken along the line 3-3 looking in the direction of the
arrows;
Fig. 4 is a vertical cross sectional view of a tubular bag
blank which when subjected to the method steps of the present
invention results in the bag as shown in Fig. 1;
Fig. 5 shows the heat sealing at the lower end of the inner
plastic ply of the blank as illustrated in Fig. 4 by the use o~ hot
compression bars applied to the outer surfaces of the contiguous
outer plies;
Fig. 6 is a vertical cross sectional view of the bag in
accordance with the invention filled with a product and showing a
heat sealing across a top zone of the inner plastic ply thereby
forming a closed pouch;
~lasl~s~
Fig. 7 is a vertical cross sectional view of the ~illed bag
showing an optional severance of the inner plastic ply during the
heat sealing at the top sealing zone thereof;
Fig. 8 is a vertical cross sectional view of the upper portion
of the filled bag illustrating a haating device for liquefying a
hot melt adhesive previously applied to the upper ends of the outer
plies;
Fig. 9 is a side view of the upper portion of the filled bag
with the outer plies folded over for passage between two pressure
rollers to close the bag;
Fig. 10 is a schematic view of the sealing end closing of the
top end of the bag as illustrated in Figs. 6-9;
Fig. 11 is an elevational view of a filled and sealed bag
having slits in the ouker ply for the removal of the contiguous
outer plies;
Fig. 12 is a perspective view o~ a filled and sealed bag as in
Fig. 11;
Fig. 13 is a perspective view of the bag of Fig. 12 showing
the filled and sealed plastic inner pouch with the contiguous outer
plies stripped away;
Fig. 14 is a front elevational view, partially broken away, of
an alternate embodiment of the invention showing the tubular bag
blank including a modified inner tubular plastic ply; and,
Fig. 15 is a horizontal cross-section of the bag shown in Fig.
14 taken along the line 15-15 looking in the direction of the
arrows.
Detaile~ D~cri~tion o~ the Invention
Throughout the Figures the reference numeral 10 is u~ed to
denote the bag made in conformance with the invention. In Fig. 1
the completed bag 10 in accordance with my invention will be seen
to comprise an inner tubular ply 12 of heat sealable material,
which may be polyethylene, or equivalent, within an outer tube 14
21~84~3
formed of a plurality of contiguous laterally offset plies 16, 18
and 20. The plies 16, 18, 20 are made of a non-heat sealable
material, such as paper. With respect to the horizontal cross
sectional view of the bag 10 shown in Fig. 2, it will be understood
that the continuous plies 16, 18, 20 are laterally off iet so that
vertical overlapping edges are spaced laterally around the bag 10
wherein pl~,7 16 is overlapped at edges 16' 16"; ply 18 is overlapped
at edges 18l 18" and ply 20 is overlapped at edges 20' 20". In the
embodiment of Figs. 1-13, the inner tubular ply 12 also is
overlapped and laterally offset at its edges 12' and 12". The
tubular formation is made in a blank form 22 illustrat~d in Fig. 4,
which blank is produced on known step end tuber devices. The inner
plastic ply 12 is heat sealed at the overlapping l~dges 121, 12" and
the overlapping edges of the mul~iple ncn-heat sealable plies 16,
18, 20 are adhesively bonded thereat, such as by a hot melt
adhesive applied in a known manner. During the formation of the
blank 22 the inner ply 12 is circumferentially bond~d at 24 at the
top end thereof to the contiguous innermost paper ply 20. From the
bond 24 downwardly the inner ply 12 remains detached from the outer
tube 14 from 26 to 28 therealong. In the embodiment of Figs. 1-13,
the inner ply 12 is generally contiguous, or co-extensive, with the
inner paper ply 20, whereby to generally have the same lateral, or
interior width edge-to-edge. The outer contiguous paper plies 16,
18, 20 are bonded, preferably by dots of adhesive, at both 1;he top
and bottom ends of the blank 22 and indicated at 30, 32 in Fig. 1.
The blank 22 is subjected to the method steps of the present
invention to result in the formation of the bag 10 shown in Figs.
1-3 as will now be explained. Attention is directed to Fig. 5
wherein a first step is made by heat sealing the plastic ply 12
across a bottom closure zone 34 caused by applying heat bars 36, 38
at opposite sides of the outer contiguous non-heat sealabl plies
16, 18, 20. As indicated by the arrows, the heat bars 36, 38 are
urged toward each other to clamp against the blank 22 and thereby
form the heat seal closure zone 34 whereupon they are moved in
opposite directions so that the heated plastic cools to closure.
21~8~8~
The heat bars 36, 38 reach a temperature level sufficient to cause
the inner ply 12 to become plastic and create a fusion bonding at
the zone 34. The temperature and time required to effectively seal
the plastic, such as polyethylene, will vary depending upon the
thickness of the material used for the inner ply 12 and the total
thickness of the outer tube 14.
Next, the bottom of the paper plies of the blank 22 are
closed. A standard pinch bottom closure is effected by folding
about fold line B-B shown in Figs. 4 and ~ to create a closure at
the lower end of the outer tube 1~. The contiguous outer plies 16,
18, 20 are oppositely stepped at both ends o~ the blank 22, as
shown in Figs. 1, 3 and 4. ~ccordingly a pinched closure may be
made at both ends of the bag 10. After making the closure at the
bottom end, a folded overlapping arrangement i5 created as shown in
Fig. 3. With reference to Figs. 1, 3, 4 and 5 it will be seen that
the bag is open at the top at 40, and is closed at the bottom end
42. At the open end 40, each ply is stepped up starting at an
outermost front 44 of the ply 16 and proceeding to an outermost
rear 46 of ply 16, with the exception of the inner plastic ply 12,
which is flush cut evenly with the innermost non-hea-t sealable ply
20. At the closed end 42, shown in Figs. 1, 3 and 5, the outer
contiguous plies 16, 18, 20 are stepped in the exact reverse order
as at the open end 40 with the plastic ply 12 flush in the same
way. Heat reactivatable hot melt adhesive 48, shown by the
stippling in Fig. 1, is applied to at least portions of the exposed
steps of both the end 40 and the end 42 of the tubular blank 22.
In the case of the end 42, the pinch closure is made while the hot
melt adhesive is still in the molten state and thus khe closure is
completed in a standard pinch bottom fashion. The inner plastic
ply 12, which has been thermally sealed at zone 3~, is loosely
folded at the closed end 42, but not bonded, with the outer tube
14. It will therefore be apparent at the closed end 42 that the
zone 34 is loosely and freely folded to lie between folded step
portions of the outer ~ontiguous plies 1~ and 20.
Closing the open end 40 is undertaken when the bag has been
2 ~ a ~
filled with a commodity or product 50 to be packaged generally in
the same way as the closed end ~2. The inner plastic ply 12 is
fused to closure by the application of heat adjacent to, but below,
the bond 24 across an upper region or zone generally referenced at
52 as shown in Fig. 6. The heat sealing is made by the application
of hot compression bars 54, 56 to the outer sides of the outer tube
14 on opposite sides of ~he bag 10, similar to the action of the
bars 36, 38 illustrated in FigO 5. Optionally, the inner ply 12
may be, but not need be, severed as shown in Fig. 7 by the
application of beveled compression rollers 58, 60 on opposite sides
of the heat sealed zone 52. The severance would depend upon the
needs of the packer and also upon the closing equipment used by the
packer of the commodity or product 50.
Following the heat sealing at 52, or at the severance thereat
by means of beveled compression rollers 58, 60, the pre-applied hot
melt adhesive 48 at the open end 40 is heated, such as by a hot air
bla~t 62, generally at the open end 40 and in the direction of the
steps of the outer plies. When melted, the outer contiguous plies
14 are folded about fold line A-A shown in Figs. 6 and 7 for
sealing the opposed outer walls by means of passing the bag between
pressure rollers 64, 66 illustrated in Fig. 9. The sequence for
the steps explained in conjunction with Figs. 6-9 for the closure
of the open end 40 are further illustrated in the schematic
illustration of Fig. 10. After the commodity or product 50 i5
filled to the desired amount within the inner plastic pouch 12, the
filled bag 10 is placed on an endless conveyer belt 68 and carried
thereon between the opposing hot compression bars 54, 56 to cause
the inner ply 12 to be heat sealed at the zone 52 at the open bag
end 40. The bag 10 is then carried between the optional beveled
severing rollers 58, 60 and then passed through the hot air blast
62 to reactivate the hot melt adhesive 48. While the adhesive is
in the melted state, the bag 10 is passed through a folding device
70, which may include the pressure rollers 64, 66, as shown in Fig.
9. To allow for adhesive set, the bag is then passed between a
pair of pressure belts 72 toward the end of the conveyer belt 68 in
- 21Q848a
fully packaged form generally denoted at 74.
~ Thus, after the filled bag 10 illustrated in Fig. 9 is closed
; in the manner described for closing th~ open end ~0, the packaged
contents 50 will be completely sealed within the plasti~ plies 12,
which provides an inner sealed pouch closed at both ends 40 and 42.
At end 42, the heat sealed folded zone 3~ may be wholly detached
~: and removed from the outer plies 14 because the ~old 34 is not
adhered there, but is loosely restrained between the ~olded plies
16, 18. Hence, when the outer paper plies 16, 18, 20 are stripped
~ away as shown in Fig. 13, the heat sealed plastic pouch 12 is left
intact, sealed, clean and ready for use of the enclosed protected
commodity or product 50. The loose non-adhesive restraint at the
zone 34 allows for the inner plastic pouch 12 to be filled without
putting undue pressure or forces on the heat sealed zone 34 and
thus maintains its integrity, prevents bag collapse, and minimizes
pinholing by remaining in the posture shown at Figs. 6 and 7 during
filling.
As a means for 0nhancing the removal of the outer tube 14, a
pair of slits 7~, shown in Fig. 11, can be made in the outer non-
heat sealable ply 20 at the closed end 42. These slits provide for
~ a lifting and stripping of the paper plies by simply sliding one's
hand between plies 20 and 18, at either, or both, of the slits 76.
In doing so, one therefore will have gained entry and begun the
process of stripping away and removing the outer paper plies, as
~ shown in Figs. 12 and 13.
As an example, the type of commodities or products that can be
packaged in the bag 10 consist of-25, 50 or 100 pound quantities of
powdered food it~ms, such as dry milk, eggs, flour, soya meal or
cereals. The bag 10 may also be used for packaging chemicals and
pharmaceuticals due to the effective heat sealed closure of the
inner plastic pouch and the assurance that the bottom seal
integrity has been maintained during filling.
Accordingly, a bag 10 formed in accordance with the embodiment
of Figs. 1-13 for the invention provides for the bonding together
of contiguous laterally offset paper plies, and binding the paper
21~8~8a
plies, or equivalent non-heat sealable material, together at
opposite ends without attachment between the ends. Then, an inn~r
plastic heat sealable ply is bonded at one end only to the outer
contiguous non-heat sealable plies. The tubular blank, as at 22 in
Figs. ~ and 5, is formed by adhering each ply to itself along the
laterally offs2t edges at 12', 12"; 16', 16"; 18', 18"; and, 20',
20" noted above. The heat sealable ply 12 resides within the non-
heat sealable outer tube 14 and the opposed walls of th~ inner ply
are then heat sealed to closure in the zone 34. Next the blank 22
is subjected to a standard pinch bottom closing procedure freely
folding the zone or flap 34 at the folded closure end 42 between
the adhered plies 16, 18, ~o in a loose non-adhesive manner. These
steps may be achieved in conjunction with the utilization of a
device as taught in U.S. Patent No. 2,897,730 to Browning.
Turning now to Figs. 14 and 15, it will be seen that an
alternate embodiment for the present invention is disclosed. In
this embodim~nt, the inner plastic ply is a seamless tube being
non-contiguous with the paper plies, particularly the adjacent
inner-most paper ply 120.
The embodiment for the alternate bag is generally denoted by
reference numeral 100. It has been learned that for certain
applications, it is important to further avoid pinholing or
rupturing of the tubular liner along the lateral vertical edges
thereof. In the embodiment shown in Figs. 1-13, wh~n the bag blank
22 is formed, the polyethylene inner ply 12 is formed tightly
against the adjacent paper ply 20 and particularly along the
lateral vertical edges. This fo~ms a pair of parallel zones that
create natural pinch points at the bag bottom when t~e bottom is
folded over in the bag bottom closing process as shown in Figs. 4,
5, 6. As a result, when the bag top is open and the inner filled
plastic pouch 20 is dumped out of the paper bag liners, the plastic
pouch resists flowing freely at the outermost lateral edges of the
bag hottom, and also potentially along the vertical edges extending
upwardly therefrom, creating a stretching of the plastic lin~r 12
at thesP places. It is not only difficult to get the plastic pouch
to relaase, but the stretching of the plastic pouch, or ply 12,
,.,.. . ., -, ~ . " ", ,,-,, ., : .: :: ,,: : , ; :
CA 0210X48~ 1998-08-11
generates weak points, whi ch could result in rupturing. Anothe
di,advantage of the longitudinally seamed construction for the
tubular ply 12 is that the adhesive bonding at the overlap
offset edg~s 12' l;~'' inherently establishes potential failure
points. While the configurcltion of Figs. 1-13 is functional and
overcomes many probLems in previous bags, t~e longitudinal seam
could also rail when the filled pouch is dumped Ollt of the paper
baq and impacts a landing surface.
As a result, the alternate embodiment of Figs. 14 and 15 is a
further improvement to the bag described with respect to Figs. l-13
by the provision of a seamless tubing 112 that solves the two major
problems discussed in the foregoing paragraph, as well as obtaining
further advantages. In reference to Fig. 14, there are likewise
provided three paper plies laterally offset as in the embodiment of
Figs. 1-13, which co~prise an outer paper ply 116, an intermediate
paper ply 1.~8 and an inner-nlost paper ply 120 inwardly arranged
around the pLastic seamless tubular liner 112. It will be observed
in Figs. 14 and 15 that the inner plastic tube ]12 is not extensive
with the paper plies as is plastic ply 12, and particularly it is
laterally spaced from the inner-most, adjacent, ply 120. The
criteria for the non-extensive tubular ply 112 in this form of the
invention is that the ply 112 have a nominal width 1/2 inch +/- 1/4
inch narrower then the nominal finished bag width, generally
defined by opposite edges 130, 132. Inner vertical lateral edges
of t:he plast..c tube 112 are generally referenced at 134, 136. The
non--extensive arrangement allows each plastic tube 112 edges 134,
136 to be spaced inwardly, preferably 1/4 inch from the respective
lateral edge of the inner-most paper ply 120. Focusing on the
lower right-hand corner of Fig. 14, bag 100 is illustrated to be
cut away to disclose the edge 136 spaced inwardly from the lateral
vertical edge 140 of the inner ply 120. This also allows a more
readily detachable arrangement when the bag is filled, and is
achieved in manufacturing when the bag bottom is folded over during
the closing process, so that the plastic ply 120 is not pinched
tight at the bag edge corners 142, 144 when later filled with
product, such as dry milk powder. Avoidance of the corner pinching
11
2~08~18a
permits the tubular ply 112 to be easily dumped from the outer
paper bags 116-120 without distortion or rupture at the left and
right hand lower corners 1~2, 144. Moreov~r, the tubular ply 112
does not require a glued or heat-sealed longitudinal seam, as at
the overlap 12' 12'' of ply 12 in the first embodiment of the
invention, and therefore eliminates the above-noted possibility of
adhesive bond/seam failure therealong.
An additional advantage of the narrower or non-extensi~e
structure for the tube 1~2 is that the natural elasticity of the
plastic material, such as the preferred polyethylene extrusion,
cooperates like a shock absorber when the bag is being filled
relative to the outer paper plies 116-120 of the bag, which are
naturally more rigid and less stretchable. The beneficial result
is that it is less likely for a bag of this construction to rupture
along bag edges 134, 136 relative to 130, 132 than co-extensive
type constructions of the prior art.
The pinch bottom closure at the bottom of the bag 100 may be
made in the same manner as explained in regard to the embo~; ~nt
for blank 22 shown in Figs. 4, 5 and 6, wherein a standard pinch
bottom closure provides a freely folding arrangement of the plastic
tube in the same manner to create a loose non-adhesive detachable
relationship.
The bag 100 comprises three or more contiguous outer paper
plies of multiwall grade paper wi~h a seamless inner plastic tube,
heat-sealable pouch 112 that is significantly narrower than the
outer paper plies. When the bag 100 is filled and ~ealed, it will
allow the outer plies of paper 11~-120 to be opened at the bag top
end with the inner pla~tic pouch remaining sealed for easy
removability from the outer paper plies without weakening, by
distortion or rupture, of the plastic pouch 112. The prior art
~eficient techni~ues for the manufacturer of plastic liners
required the inner plastic pouch in flat bags to be contiguous with
the outer paper plies or within the edge folds for gussetted bags.
In manufacturing that way, those bags would not function to allow
the inner plastic pouch to remain assuredly sealed and easily
removable from the outer paper plies without weakening by the said
12
21 08~a
distortion or rupture of the plastic pouches provided. It should
be noted that even small percentage failure rates in the food
packaging industry can not be tolerated. One bag ~ailure per 1000
could result in the rejection of a whole shipment of packages. The
failures of these prior art bags occurred because the inner plastic
pouch would be folded tightly in the opposed corners, as in the
region of 142, 144 of the present invention, while the bag bottom
was formed and/or closed. This r~sulted in a tight-folded corner
and a pinching of the plastic pouch between the paper plies at the
closure fold o~ the bag bottom corners in the location of great
stress and pressure during the filling of the bag. The resistance
to releasing the plastic pouch from the corners of the outer papPr
bag plies at these pinch point causes stretching or distortion of
the plastic pouch there. An elastic pouch made that way is
susceptible to rupture mainly at one or both of the bottom corners
and secondarily at places upwardly therefrom extending possibly to
the top of the bag.
The embodiment as shown in Figs. 14 and 15 eliminates the
distortion by positioning the outer edges of the plastic pouch 112
significantly inwardly from the contiguous outer paper plies
thereby eliminating the tight folded corners as illui~trated by the
cross-sectional view of Fig. 15. Fig. 15 also makes clear the
seamless configuration of the tube 112 wherein there are no lateral
offsets stepped zones of adhesive seaming or hot melt bonding, such
as between 12' and 12 " shown in the first ~mbodiment of the
invention.
The b~g 100 in accordance with Figs. 14 and 15 provides a
plastic tubular non-extensive tubular liner or pouch 112 that is
easily removable and free o~ distortion or rupture during bag
filling and subsequent dumping of the filled plastic liner from the
outer paper plies by the end user.
Accordingly, the invention has been described in conjunction
with a preferred embodiment and with means for conducting the
method steps. However, the specification and description are
provided in connection with explaining only one embodiment of the
invention and it is envisioned that a wide scope of equivalents
~all within the claims appended hereto.
13
