Note: Descriptions are shown in the official language in which they were submitted.
FIELD OF INVENTION
. . _
Thls invention relates to packages for cheese, luncheon meant and
the like. Specifically, the invention relates to an easy open seal for such
packages and further relates to means to close such packages once they are
opened.
BACKGROUND
Cheese, luncheon meat, and similar products and commodities are
packaged today in a thermoplastic film which is overwrapped about the article
to be packaged and the film is heat sealed to itself to form closure seams.
After the package is heat sealed, it is a problem to open the package
without destroying the package and leaving it unsuitable for further use. The
problem is compounded because the films for packaging such products as cheese
and luncheon meat should be strong and abuse resistant and have desirable gas
transmission properties yet at the same time be capable of being opened without
destroying the package. Thus, it is a principal object of this invention to
provide a closure and seal configuration which is easily opened hy a relatively
small opening force and does not destroy the package.
Numerous seal configurations have been proposed in the past which employ
easy open features. For example, U.S. Patent 2,963,396 shows an opening and
separating feature for a thermoplastic film package wherein a gusset type fold
provides grippable pull-apart tabs. U.S. Patent No. 3,536,501 which issued on
October 27, 1970 to W. A. Work shows a package in which the edge of the closure
flap is folded over so that the outer film layer is sealed to itself. French
Patent No. 1,331,100 which was filed January 22, 1962 naming Mme. Beernaert
(formerly Germaine Malard) as inventor shows a package with a closure seal in
which the edges of the mouth of the receptacle are folded outwardly and then a
heat seal is placed through the four layers of film. U.S. Patent No. 3,655,503
--2--
r.~
401/850515/1/1
which issued on April 11, 1972 to Hugh E. Stanley and George M. Tbkos shows a
package closure seal in which multilayer Eilms are sealed togeth~r and when
pulled a~art to cpen the package the outer layer of one film ruptures and
delaminates only in the seal area. Another object of the present invention is
to provide a package and seal configuration improved over the aforementione~
and other presently available designs.
Another problem encountered in packages for cheese and luncheon
meat is that often ~nly a portion of the product is consumed at one time
and it is desirable that the package be effectively reclosed ~o
protect the remaining portion. Numerous reclosure elements have ~een
proposed in the prior art including those disclosed in U. S. Patent No~
4,174,597 which issued November ~0, 1979 to ~ ~ li et al; U. S. Patent No.
4,138,932 which issued Februaly 13, 1979 to Mowli et al; U. S. Patent
No. 4,126,085 which issued November 21, 19?8 to Mowli et al and U. S. Patent
No. 4,117,934 which issued October 3, ]978 to Mowli et al, all of which
emplo~ "twist tie~ elements with dead fold characteristics, i.e., once
~ent or folded the element remlins in its bent shape and d oe s not spr m g
back or tend to return to its original shape.
Ihe above cbjects are achieved by the present invention which
is better understood by reEerence to the following summQry of the invention,
description of the drawings, and detailed description.
SUMM~RY OF THE INVENTION
In one aspect the present invention is a method of making an
easy cpen package having an int2gral dead fold element comprising the
steps of:
(a) prcvidLng a side seal bag constructed of flexible
therm~plastic film material, said film having at least
tw~ layers, said bay having an open end and a closed e~d;
(b) removing corner portions of said bag adjacen-t
to said end opening so that two extended lip por-tions are
:Eormed;
(c) a-ttaching a strip-like dead fold elemen-t to an
inner surface of at leas-t one of said extended lip portions;
(d) folding said extended lip portions into said
end opening so as to surround and encompass said dead fold
element within the fold of the lip portion -to which the element
is attached, said folds bringing portions of the outer surface
of the bag into direct contact;
(e) flattening and heat sealing said folded li.p
portions to enclose said dead fold element within its respective
fold and to close said bag, said heat seal being -transverse
across the width of the bag and being located bètween the fold
line and the edge of inwardly folded lips, said folds providing
grippable tabs for pulling said folds apart to open said bag,
the rupture strength of -the outer layer being greater than -the
bond strength between the outer layer and the layer adjacent
thereto whereby when the -tabs are gripped and pulled apart the
outer layer first ruptures then delaminates -to the end of the
folded lip por-tion to open said bag; and,
(f) filling said bag with a product prior to -the
application of the heat seal in step (e) whereby an easy open
package with a reclosable dead fold closure element is provided.
In another aspect, the present invention is a package
having a reclosable feature comprising:
(a) a bag constructed from a multi-layer thermoplastic
packaging film, said film having at leas-t two layers, said bag
having a closed end and a mouth end;
(b) an inward fold of the lip of the mouth of said
bag, said fold being along a line so that por-tions of the ou-ter
surface of said bag are in direct contac-t;
,~
(c) a product wi-thin the bag;
(d) a transverse heat seal across -the width of the
bag, said seal being located between the fold line and the edge
of the folded under lip, said outer surface portions being
sealed together by said seal said folds providing grlppable
tabs which can be pulled apart to open said bag, -the rupture
strength of the outer layer being greater than the bond strength
between the outer layer and the layer adjacent thereto whereby
when the tabs are gripped and pulled apart the outer layer first
ruptures then delaminates to the end of the Lolded lip portion
to open said bag; and,
(e) a strip-like dead-fold element located within
and enclosed by one of said folds along approximately one-half
of said mouth whereby after said bag is opened it may be closed
by bending said dead-fold element.
DESCRIPTION OF DRAWINGS
Attached here-to and made a part of this disclosure are
the drawings showing principal features of the subject invention
and in which:
Figure 1 is an exaggera-ted schematic representation
of the seal area showing rupture of one outer layer and delamin-
ation thereof from an adjacent layer;
Figure 2 is a cross-section in exaggerated detail of
one embodiment of the package of the present invention;
Figure 3 is a top view of the embodiment shown in
Figure 2;
Figure ~ is a top view of a flattened bag prior -to
being provided with a dead-fold element and final seal; and,
Figure 5 is a top view of a flattened bag ready to
receive a product before final sealing.
PREFERRED EMBODIMENT
Referring first to Figure 2 a product 6 which may be
-5-
cheese or luncheon meat is shown enclosed by mul-t.ilayer film F.
The receptacle made from multilayer film F can be formed in
several different manners and may be
-Sa-
called a bag, pouch, package, etc. In ~he preferred embodiment a seamless
tube of the three-layer film F is c:Losed at one end by end seal 13 which
forms the bottom of bag or receptacle R. The receptacle is loaded with
product 6 and, to close the loaded receptacle, an inward fold is made at
its open end or mouth along line 12 wherein edges 9 and 10 are folded
under so that they mate or coincide when the bag mouth is flattenecl. In
the flattened condition a heat seal i8 applied by compressing the four
layers of material in the seal area region A. All of the surfaces in
contact in seal Region A will be sealed to each other. This configuration
leaves separable tabs 4 and 5 which may be gripped by the fingers to pull
tlle seal apart. When this occurs rupture and delamination shown in Figure
1 occurs.
In Figure 1 seal area A represents the seal which actually closes
the opening to the receptacle or bag R. The seal is designated seal S in
Figures 1 and 2. When tabs 4 and 5 are grasped between the fingers and pulled
apart a delamination occurs at the beginning of the seal S in the area A as
shown in Figure 1 and the delamination between layer 3 and its adjacent
layer 2 continues to the edge E of the film so that opening 20 now provides
access to the interior of the bag through the ruptured outer layer 3 of
film F-1 of tab 4 and through the delamination between layer 3 and its adjacent
layer 2 which continues to the edge of the film E. From this opening the
product 6 may be removed and reinserted into the bag.
Referring to Figure 19 it is seen that the film F from which the bag
is formed is a three-layer film having inner layer 1, middle or adjacent layer
2 and outer layer 3. (In Figure 2 it can be seen that outer layer 3 is on the
outside of the bag.) A preferred three-layer film is that disclosed in U.S.
Patent No. 4,278,738 which issued on July 14, 1981 to Harri J. Brax et al.
Relating the Brax et al film to the layers to Figure 1, inner layer 1 is
401/850515/1/2
~:192~
an ethylene-vinyl acetate copolymer which has been cross linked by irradiation
and has a thickness of approximately l.5 mils; middle layer 2 is a copolymer of
vinylidene chloride having a thickness of approximately 0.2 mils; and outer
layer 3 is a crossl:inked ethylene vinyl acetate copolymer having a thickness ofapproximately 0.7 mils. The vinyl acetate content in the ethylene-vinyl acetatecopolymers is approximately 10% and the vinylidene chloride copolymer is a
copolymer of vinylidene chloride and vinyl chloride in a mixture of 10% suspension
polymerized and 90% emulsion polymerized copolymers. The emulsion polymerized
copolymer consists of about 70% vinylidene chloride and 30% vinyl chloride and
the suspension polymerized copolymer consists of about 80% vinyl:idene chloride
and 20% vinyl chloride.
Using the film described above, which is available in a seamless
tube so that an end seal 13 can be applied to close the bottom of the bag,
the top of the bag when folded in a configuration shown in Figure 2
have the appearance shown in Figure 3 when laid flat. In this position, a
heat seal can be applied across the width of the bag in area A. The width of
the seal is one-eighth inch to one-quarter inch in width and can be applied
by a sealing unit such as those made by the Vertrod Corporation of Brooklyn,
New York or by any other heat seal unit as these are well known in the art.
A pressure of approximately twelve kilograms per centimeter is preferred and thesealing unit is set such that the temperature at the interfaces where sealing
occurs is in the range of 225F to 300F. In a laboratory arrangement the totalsealing time consists of approximately 0.6 seconds for preheating the seal bars,0.3 seconds for the heated welding time as the pressure is applied to the area
A, and approximately 0.1 seconds for release time. In a production operation
the seal bars do not have time to cool and the preheat time will drop to
approximately 0.1 second for a total sealing time of approximately 0.5 seconds.
A seal according to the foregoing will keep the package intact and
401/850515/1/3
~9~ 7
will resist abuse yet the seal can be readily opened by grasping the tabs 4
and 5 of Figure 2 and pulling the~ apart whereupon one of the layers 3 as ln
Figure 1 ruptures and delaminates to film edge E-1 or E-2. DelaminatLon i.s
observed to occur rather than rerupture of the outer layer 3.
A reclosure feature is provided which can be a "twist-tie" strip or
any piece of wire or other material which has dead-fold characteristics. Strip 7
is located within one of the end folds as shown in cross section in Figure 2 or
in the top view in Figure 3. The dead-fold strip 7 can be inserted by simply
punching a hold as indicated by the dotted lines 21 in Figure 2 and inserting the
dead-fold strip into the hole. After the bag has been opened, it can be
readily closed by rolling up the said bag material in the area 23 as
one rolls up the used end of a tube of toothpaste and then crimping
or bending the dead-fold strip to hold the roll of film material 23 secure.
Another method of providing a reclosure feature is shown in
Figures 4 and 5. In Figure 4 a side seal bag or receptacle R is shown which
has been formed by folding a sheet of film in its center and sealing
it along its sides by heat seals 26. At the open end of the bag the
corners are removed by cutting along dotted lines 27. When the corners are
removed two opposed lips are formed which may readily be folded inside the
bag. When the upper lip is folded in dead fold strip 7 having an adhesive
surface is laid upon and secured to the upper surface of the lower lip
afterwhich the lower lip is folded inwardly. The bag now has the configuration
shown in Figure 5 with the edges F of the lips coinciding inside the bag, the
lips having been folded along fold line 12. The bag is now ready to receive
a product and when filled a transverse heat seal is applied in the area A
which closes and seals the bag with portions of the outer surface of the
bag being sealed to itself in the area A. Film segments may be removed at 24
by punching or cutting. The removal of these segments tends to relieve the
stress on the side seals when the fold tabs are pulled apart and direct the
stress to seal area A to open the package.
401/850515/1/4
Other materials which can be suitably used in the present
invention are polyethylene and ethylene-vinyl acetate copolymers in
general for the mater:ial for the outer layer and for the material of the
adjacent layer materials can be selected from the group consisting of
nylon, vinylidene chloride copolymers, propylene homopolymers and copolymers;
and, cross-li.nked polyethylene and ethylene-vinyl acetate copolymers.
The ch:ief criterion is that the tensile strength or rupture strength of
the outer layer is greater than the bond strength between layers 2 and
3. Likewise, the bond strength between layers 2 and 3 has to be less
than the rupture or tensile strength of adjacent layer 2 or of the
combination of layers 1 and 2.
Other folding configurations are possible within the scope of
the present invention as long as the fold results in outer layer 3 being
sealed to itself in a face-to-face relationship so that when the rupture
occurs there is delamination to a nearby or adjacent edge of the film
resulting in an access opening to ehe interior of the package.
Having thus described my invention, I claim:
401/85051511/5
