Note: Descriptions are shown in the official language in which they were submitted.
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HE~OD OF MARIN~ RECLOBABLB PL~TIC ~A~B ON A FORM FILL AND BEAL
MAC~INB
Backaround of the Invention
The present invention relates to improvements in the method
of manufacturing reclosable plastic bags and more particularly to
a method which permits such bags to be formed as they are fed
over a filling spout of a filling machine whereby the bags are
formed and simultaneously filled with a product.
The art of making reclosable plastic bags provided with
mating profiles which form a zipper to render the bags reclosable
is well defined in prior patents. Such patents are discussed, for
example in V.S. Patents 4,894,975 and 4,709,533. ~he last
mentioned patent further describes a method and apparatus which
permits the bags to be formed in situ about the filling spout:of
a filling machine. In accordance with the disclosed method the
lateral edges of a film are brought together and the surfaces
adjacent the edges are joined together in a fin seal to form the
sealed top of a bag. Zipper strips are brought to the inside of
the film between the filling spout and the fin seal to provide a
reclosable closure between the fin seal and the contents of the
bag.
The method disclosed in the above referenced patent
4,709,533 results in bags in which the zipper is initially
disposed within the finished bag. This method as well as other
systems proposed in the past either had the zipper inside the
tube, (i.e. between the tube and the filling spout) or positioned
between the free edges of the tube. These systems required
fairly complex arrangements of guides and sealing bars, which
tended to cr~ate additional potential prohl~C during the
manufacturing process. Hence it became desireable to simplify as
much as possible the method of attaching the zipper to the film.
Furthermore, the customer of the packaged product had to first
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cut open the bag before the zipper became evident. As a result
much of the eye appeal and hence value added of the zippered
packaging could be lost on a customer of the product packaged
within the bag. In addition, since the zipper was initially
within the package its subsequent operation could be interfered
with by the contents of the package, particularly when the
contents are in a powder form.
~ummarv of the Invention
L0 In view of the above it is a principal object of the presen
invention to provide an improved method of forming reclosable
plastic bags in situ at a form, fill and seal machine in which
the zipper is initially disposed on the outside of the bag.
A further object is to provide such a method wherein the bag I
so produced completely seals the product packaged therein.
A still further object is to provide such a method wherein a
security seal is provided on the final package so as to provide
ready evidence of tampering with the package or its contents.
Still another object is to provide such a zippered package
wherein the zipper is protected from the contents of the package
prior to and after the package is opened.
In accordance with the present invention a method is
provided for forming a reclosable plastic bag in situ at a form,
fill and seal machine by continuously feeding a film of plastic
material and forming it into a tube about a filling spout of the
machine. A plastic zipper strip having first and second
interlocking members is fed parallel to the tube and attached to
the outside of the film on the surface opposite to that directed
towards the f~lling spout. The interlock;ng ~ rs are
preferably disposed on strips provided with a web on at least one
side of each interlocking member with the webs being attached to
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the film. The film between the zipper and pouring spout may be
pleated 60 as to provide a pouring spout or a gasket for the
final bag.
Brief Descrl~tion of the Draw~ nas
In the accompanying drawings:
Fig. 1 is a simplified perspective view of a form fill and '
seal operation in accordance with the present invention:
Fig. 2 ls a plan view of a typical bag formed in accordance
L0 with the form fill and seal operation of the present
invention:
Fig. 3 is an enlarged cross sectional view of the top of th
bag shown in Fig. 2 taken along reference lines 3-3;
Fig. 4 is a simplified perspective view of a form fill and
seal operation in accordance with the present invention depicting
a different type of zipper being utilized;
Fig. 5 is a fragmentary enlarged cross sectional view of
Fig. 4 taken along reference lines 5-5;
Fig. 6 is a fragmentary perspective view of the zippered
tube formed on the equipment depicted in Fig. 4:
Fig. 7 is an enlarged, exaggerated sectional view of a
reclosable bag formed in accordance with the present invention
depicting a tube construction which provides for a pouring spout
or gasket; appearing with Figs. 2 and 3;
Fig. 8 is a view similar to Fig. 7 but with the interlocking
members of the zipper open; and
Fig. 9 is a fragmentary sectional view of a portion of a
package formed utilizing the zipper shown in Fig. 5 and depicting
a tube construction that provides for a pouring spout or a
gasket; and
Fig. 10 is a variation of Fig. 9.
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Detailed De9cription of the Preferre~ Embodiment
Reference ls now made to the drawings and to Fig. 1 in
particular wherein the filling spout 10 of a conventional
vertical form fill and seal machine 12 is depicted. In a usual
manner a continuous supply of a film 14 is brought from a supply
roll about suitable guides to be wrapped into a tube 16 about the
filling spout 10. To this end a longitudinal seal 18 and a pair
of transverse or cross seals 20, 22 are formed as the tube 16
0 passes over the filling spout 10 so as to seal the sides and
seam the film into a final package 24 as shown in Fig. 2. Thus,
as the film 14 passes around the filling spout 10 the lateral
edges of the film are overlapped and a longitudinal seam 18 is
formed by heat sealing bar 26 so as to transform the film into a
tube 16. The tube is flattened and a downstream cross seam 20 is
- formed by heat sealing bars 28 sealing the bottom of the tube and
the tube is then filled with product as it continues to move
downstream. After the filling operation is completed the tube is
collapsed and an upstream cross seam 22 is formed by the heat
sealing bars thereby completing the package about the product.
The sealing bars 28 simultaneously cut the tube in the upstream
seam thereby separating the filled package 24 from the tube and
forming the downstream cross seam 20 for the next package. The
process is then repeated.
In accordance with the present invention, as the film 14
passes the filling spout 10 a zipper strip 30 is fed from a
supply roll (not shown) past appropriate guides 32, 34 to abut
the outside of the tube 16. That is the zipper strip 30 is
positioned to a~`-t against the surface of t~lbe '' ~ppnsite to the
surface directed toward the filling spout 10. The zipper strip 30 .-~
and tube 16 are fed in this abutting condition past a pair of .
sealing bars 36, 38 which seal the zipper strip 30 to the tube
along seal lines 40, 42. It should be appreciated that the seal
lines 40, 42 may be circumferentially spaced from the
longitudinal seal 18 as shown in figure 1, straddle the
longitudinal seal or even overlie the longitudinal seal. Thus,
since the zipper is on the outside of the tube, it can be easily
positioned at any location relative to said tube.
The zipper strip 30 is commonly formed of a thermoplastic
material such as polyethylene. Similarly, for many products the
film 14 may be polyethylene or a similar thermoplastic and hence
the zipper and film may be heat bonded to one another. In other
cases a moisture, odor or other barrier layer may be necessary to
protect the contents of the package. If a barrier layer is
provided on the film which prevents the zipper from being heat
sealed to the film, the zipper strip 30 may be provided with
stripes of a reactivatable adhesive to form an adhesive bonding
with the film. In such cases the seal bars 36, 38 serve to guide
the zipper strip against the film and to provide sufficient
pressure to effect the adhesive bondinq. Said bars can also be
replaced by pressure rollers.
Referring to Fig. 3, it can be seen that the zipper strip 30
comprises a first interlocking member 44 and a second
interlocking member 46. The member 46 includes a profile section
48 and an adjacent web section 50 whereas the member 44 includes
a mating profile section 52 disposed between web sections 54 and
56. The web sections 50 and 56 are bonded to the tube 16, along
seal lines 42 and 40 respectively, providing a hinged attachment
for the zipper strip. The web section 54 provides a convenient
flange to permit ~e ultimate user to grip in Q-d-- ' to separate
the zipper members and provide access to the underlying tube
section 58 which must ultimately be ruptured to provide access to
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~he package contents. The existence of a rupture in tube section
58 thus provides evidence of the package having been previously
opened or tampered with.
A rod or other means may be provided to form a crease in the
tube to provide a pleat or gusset in the final bag in a
conventional manner. This can be used to form a tube as shown in
Fig. 7 wherein the tube section 58 behind the zipper 30 is
pleated. To gain access to the contents of the package, the
interlocking members 44, 46 of zipper 30 are separated (as shown
0 in Fig. 8) and the apex 60 of the pleat must be cut or punctured.
The pleat 58 is sufficiently deep so that the material
defining the sides 62, 64 of pleat 58 may be pulled between the
separated zipper profiles 48 and 52 to provide a funnel which
when punctured will facilitate pouring out the contents of the
package 24 or when slit will protect the profiles from being
clogged by powder type materials. Further, the material of one
or both sides 62, 64 may be positioned between the profiles 48,
52 when the zipper is reclosed to provide a sealing membrane
between the profiles for better liquid tightness and/or to
protect the profiles form powdered materials.
Figs. 4 through 6 show the modifications to the form fill
and seal machine 12 and the final package 24 which enable use of
a different type of zipper 90. This zipper will extend beyond
the edge 92 of the finished package 24 (as shown in Figs. 5 and
6) rather than being positioned on a side of the finished package
as shown in Fig. 2. Thus, in Fig. 5 the interlocking zipper .-
members 66 and 68 are positioned to straddle an edge of the
collapsed tube 16. Zipper member 66 includes a male profile
member 70 between eb sections 72 and 74 while z~p~-- member 68
includes a female profile member 76 between webs 78 and 80. In
this case one web 72 and 80 of each interlocking member 70 and 76
is secured to the tube 16 on its opposite sides, while the other
webs 74 and 78 form gripping flanges to facilitate opening of the
package. In Fig. 9, the embodied tube section 82 is pleated
below the zipper interlocking member 70 and 76 so as to provide a
funnel or sealing membrane as discussed previously. In addition,
the zipper of Flg. 9 can have its webs 74 and 78 joined at
juncture 83 (as shown in Fig. 10) to provide for an additional
tamper evident feature.
Thus, in accordance with the above, the aforementioned
O objec are effectLvely attaLned.
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