U.S. patent number 3,596,428 [Application Number 04/765,289] was granted by the patent office on 1971-08-03 for packaging process and apparatus.
This patent grant is currently assigned to American Maize Products Company. Invention is credited to Charles Wallace, Robert Wolfelsperger, William E. Young.
United States Patent |
3,596,428 |
Young , et al. |
August 3, 1971 |
PACKAGING PROCESS AND APPARATUS
Abstract
A process and apparatus particularly adapted for packaging food
stuff in a water-soluble and preferably edible starch film
manufactured to certain specified characteristics which for the
first time makes it possible to form a water-soluble package sealed
with a solvent activator such as water which is applied in a
controlled manner to the film to preserve its strength so that
tension may be applied to advance the film through a high-speed
automatic packaging machine.
Inventors: |
Young; William E. (Stamford,
CT), Wolfelsperger; Robert (Fairfield, NJ), Wallace;
Charles (Glen Rock, NJ) |
Assignee: |
American Maize Products Company
(N/A)
|
Family
ID: |
25073137 |
Appl.
No.: |
04/765,289 |
Filed: |
October 7, 1968 |
Current U.S.
Class: |
53/451; 53/553;
426/138; 426/415; 53/455; 53/562; 426/410 |
Current CPC
Class: |
B65B
9/023 (20130101) |
Current International
Class: |
B65B
9/02 (20060101); B65B 9/00 (20060101); B65b
009/02 () |
Field of
Search: |
;53/28,180,29,183
;106/213 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Condon; Theron E.
Assistant Examiner: Desmond; E. F.
Claims
We claim:
1. A process for manufacturing packages made with water-soluble
film having a tensile strength of at least about 500 p.s.i. and a
stiffness of at least about 2.5 grams in a machine of the type
which includes an applicator for applying solvent activator to the
film which comprises the steps of applying tension to such film to
advance it through the machine, applying a controlled amount of
solvent activator to preselected areas of such film before any part
of the package is formed, moving portions of said film into a
sealing alignment with at least one of said portions being a
preselected area, pressing said portions together to form a seal
and a film package envelope open at one end thereof, filling the
package through the open end thereof, pressing second portions of
said film together at least one of which is a preselected area to
seal the open end of the package and moving said filled package out
of the machine.
2. A process as specified in claim 1 which includes the step of
pressing one preselected area against another preselected area to
form both of the said seals in the filled package.
3. The process specified in claim 1 further comprising the step of
applying heat to said preselected areas of said film conjointly
with the step of applying pressure to form said seal.
4. The process specified in claim 2 further comprising the step of
applying heat to said preselected areas of said film conjointly
with the step of applying pressure to form said seal.
5. The process specified in claim 1 further comprising the step of
applying a solvent activator consisting of water to said film.
6. The process specified in claim 2 further comprising the step of
applying a solvent activator consisting of water to said film.
7. The process specified in claim 1 further comprising the step of
applying a solvent activator consisting of water and an additive to
said film.
8. The process specified in claim 2 further comprising the step of
applying a solvent activator consisting of water and an additive to
said film.
9. The process specified in claim 1 further comprising the steps of
applying said solvent activator to said film in discrete
droplets.
10. The process specified in claim 2 further comprising the steps
of applying said solvent activator to said film in discrete
droplets.
11. The process specified in claim 9 further comprising the step of
applying between 30 and 230 discrete droplets per linear inch to
said preselected areas of said film.
12. The process specified in claim 10 further comprising the step
of applying between 30 and 230 discrete droplets per linear inch to
said preselected areas of said film.
13. The process specified in claim 1 further comprising the step of
advancing the filled package out of the machine such that the film
following the package completely supports the weight of at least
one filled package.
14. The process specified in claim 2 further comprising the step of
advancing the filled package out of the machine such that the film
following the package completely supports the weight of at least
one filled package.
15. A process for manufacturing packages made with at least two
strips of water-soluble starch film each having a tensile strength
of at least about 500 p.s.i. and a stiffness of at least about 2.5
grams in a machine of the type which includes an etched roll for
applying water to the film strips to make it adhesive which
comprises the steps of: applying tension to a first strip of such
film, applying between 30 and 230 discrete droplets of water per
linear inch to preselected areas of at least one of said film
strips to activate and tackify the surface thereof before any part
of the package is formed, moving said first and a second strip of
film into sealing alignment with each other by the continued
application of tension to the said film strips, pressing a portion
of said first and second strips of film together to form a
longitudinal seal between the two strips of film along a line at
opposite ends thereof, pressing said two strips of film together to
make a first cross seal across the film strips between said
longitudinal seals to form a package envelope open at one end
thereof, filling the package envelope by depositing material
between said longitudinal seals and against said first cross seal,
moving said package envelope under tension to another station and
pressing said two strips of film together to make a second cross
seal and form a final package and moving said final package out of
said machine by the application of tension to said film strips.
16. A process as in claim 15 wherein 150 discrete droplets per
linear inch are deposited on said film strip.
17. A process as in claim 16 wherein the 150 discrete droplets per
linear inch are deposited on both strips of film.
18. A process as in claim 17 further comprising the step of
stopping the film advance during the time that pressure is applied
to the strips of film to form a seal.
19. A process for manufacturing packages made with at least two
strips of water-soluble starch film having a tensile strength of at
least about 500 p.s.i. and a stiffness of at least about 2.5 grams
in a machine of the type which includes an etched roll for applying
water to the film to make it adhesive which comprises the steps of:
applying between 30 and 230 discrete droplets of water per linear
inch to at least one of said film strips to activate and tackify
the surface thereof before any part of the package is formed,
moving said first and a second strip of film into sealing alignment
with each other, pressing a portion of said first and second strips
of film together to form the package for material contained
therein.
20. A process for manufacturing packages made with at least two
strips of water-soluble film having a tensile strength of at least
about b 500 p.s.i. and a stiffness of at least about 2.5 grams
which includes an applicator for applying water to the film which
comprises the steps of: applying tension to a first strip of such
film applying solvent activator to preselected areas of at least
one of said film strips to activate and tackify the surface thereof
before any part of the package is formed, depositing material on
one of said strips of film, bringing said strips of film into
sealing alignment and applying pressure to said strips of film to
seal said package and moving said package out of said machine under
tension.
21. An apparatus for manufacturing packages made with water-soluble
film comprising means for applying tension solely to the
water-soluble film to advance it through the apparatus, means for
applying a controlled amount of activator in the form of discrete
droplets to preselected areas of said film before any part of the
package is formed, sufficient to activate the surface of the film
but insufficient to reduce the strength of the film below that
needed to withstand the tension forces applied to the film, means
for moving portions of said film into a sealing alignment with at
least one of said portions being a preselected area, means for
pressing said portions together to form a seal and a film package
envelope open at one end thereof, means for filling said package
envelope through the open end thereof, means for pressing second
portions of said film together at least one of which is a
preselected area to seal the open end of the package envelope and
means for applying tension to move the final package out of the
apparatus.
22. An apparatus as specified in claim 28 wherein said means for
applying a controlled amount of activator to preselected areas of
said film comprises an etched roll having a screen rating of
between 30 and 230, said roller being positively driven at a speed
consistent with the speed of applying pressure to seal said
packages, said etched roll being rotatable through a solvent
activator bath whereby solvent activator is picked up in the etched
area of said roll for deposition on said film, means for keeping
the film in contact with said etched roll and means for removing
excess solvent activator from the surface of said etched roll to
confine the solvent activator only to the etched areas of said
roll.
23. An apparatus as in claim 22 wherein said screen rating is
150.
24. An apparatus as in claim 22 further comprising means for
adjusting the angle of contact of said film to said etched roll to
vary the time the film is in contact with said roll.
25. An apparatus as specified in claim 21 further comprising means
for applying heat to said film conjointly with said pressure to
form a seal.
26. An apparatus as specified in claim 21 wherein said solvent
activator is water.
27. An apparatus as specified in claim 21 further comprising means
for applying solvent activator to preselected areas of each of two
strips of film.
28. An apparatus as in claim 22 further comprising a dancer bar
interposed between said etched roll and said means for pressing a
portion of said preselected areas and film together to keep tension
on said film and to prevent said film from forming into loops.
29. An apparatus as specified in claim 27 wherein said means for
applying solvent activator to preselected areas of each of two
strips of film comprises two etched rolls, each of said etched
rolls being rotatable through a solvent activator bath whereby
solvent activator is picked up in the etched area of each of said
roll and deposited on said two film strips and means for pressing
the preselected areas of each film strip together to form a
seal.
30. An apparatus for manufacturing packages made with water-soluble
film having a tensile strength of at least about 500 p.s.i. and a
stiffness of at least about 2.5 grams comprising means for applying
tension to the film to advance it through the apparatus, at least
two etched rolls rotatable in a solvent activator bath, said etched
roll having a screen rating of between 30 and 230 for applying
solvent activator to at least two strips of film, said applicator
pulling film from a storage roll, said etched rolls applying a
controlled amount of solvent activator to said strips of film,
means for bringing said preselected areas into sealing alignment
with each other, a first set of sealing bars to apply pressure to
seal a first portion of said film strips, at least one dancer bar
interposed between said first set of sealing bars and said etched
roll to take up slack in said film strips and to keep said film
strips under tension, a second set of seal bars for pressing said
film strips together to form a package envelope open at one end
thereof, means for filling said package envelope through the open
end thereof, said second set of seal bars pressing said strips of
film together a second time to complete said package and means for
moving said package out of said machine under tension.
31. A process for manufacturing packages of water-soluble film in a
machine of the type which includes an applicator for applying
solvent activator to the film to make it adhesive which comprises
the steps of pulling at least a first and a second strip of such
film through the machine, applying a controlled amount of solvent
activator in the form of discrete droplets to preselected areas of
at least one of said film strips to activate the surface and make
it adhesive, moving said strips of film into sealing alignment with
each other, pressing together a portion of at least two of said
film strips including part of the preselected area to form a seal
between the two strips of film and a packaging envelope with an
opening therein, filling the package through such opening, pressing
together a second portion of the same two film strips including
part of the preselected area to seal the opening in the package and
then removing said package from the machine.
32. The process specified in claim 31 which includes the step of
applying between about 30 to 230 discrete droplets of solvent
activator to preselected areas of at least one of said film
strips.
33. The process specified in claim 31 which includes the step of
applying heat to the film when it is pressed together to form a
seal.
34. A process for manufacturing packages of water-soluble film in a
machine of the type which includes an applicator for applying
solvent activator to the film to make it adhesive which comprises
the steps of pulling at least a first and a second strip of such
film through the machine, applying a controlled amount of solvent
activator which consists of water and an additive to preselected
areas of at least one of said film strips to tackify the surface
and make it adhesive, moving said strips of film into sealing
alignment with each other, pressing together a portion of at least
two of said film strips including part of the preselected area to
form a seal between the two strips of film and a packaging envelope
with an opening therein, filling the package through such opening,
pressing together a second portion of the same two film strips
including part of the preselected area to seal the opening in the
package and then removing said package from the machine.
35. A process for manufacturing packages of water-soluble film in a
machine of the type which includes an applicator for applying
solvent activator to the film to make it adhesive which comprises
the steps of pulling at least a first and a second strip of such
film through the machine, applying a controlled amount of solvent
in the form of discrete droplets in an area along the length at
each side of at least one of said film strips and periodically
applying a controlled amount of solvent activator in the form of
discrete droplets in an area across the width of at least one of
said film strips to tackify the surface and make it adhesive,
moving said strips of film into sealing alignment and then pressing
a portion of the adhesive area at both sides along the length of
said strip against a second one of said strips without pressing the
strips together across the entire width thereof to form a first
longitudinal seal at both sides of said strips and thereafter
pressing one of said adhesive areas positioned across said strip
against the second one of said strips to form a second seal and a
packaging envelope with an opening between said longitudinal seals,
filling the package envelope through such opening, and then
pressing a second one of said adhesive areas across said strip
against the second one of said strips to seal the opening in the
filled package and to form a second packaging envelope.
36. An apparatus for manufacturing packages made with water-soluble
film which comprises, means for pulling at least one strip of such
film to advance it through the apparatus, means for applying a
controlled amount of solvent activator in the form of discrete
droplets to the film in an area along the length of at least one
side of said film and for applying a controlled amount of solvent
activator in the form of discrete droplets periodically in an area
across the width of at least one film strip to activate the surface
and make it adhesive, means for moving said adhesive areas into
sealing alignment with a portion of unactivated film, means for
pressing the adhesive area along the length of at least one side of
the film against the unactivated film to establish a first
longitudinal seal without pressing the film together across the
entire width thereof, means for thereafter pressing one of said
adhesive areas across the width of the film against unactivated
film to establish a second seal which forms a packaging envelope
with an opening across a portion of the width at one end thereof
and which at the same time completely encloses the preceding
packaging envelope and means for filling the packaging envelope
through said opening.
37. The apparatus specified in claim 36 which includes means for
pulling at least two strips of film to advance them through the
machine and in which said means for applying solvent activator is
adapted to apply solvent activator to at least one strip of film in
an area along the length at both sides of at least one film strip
and in which the means for establishing the first longitudinal seal
is adapted to press the adhesive area along both sides of the film
against inactive film to establish a longitudinal seal at both
sides of the packaging envelope.
38. A process for manufacturing packages of water-soluble film in a
machine of the type which includes an applicator for applying
solvent activator to the film to make it adhesive which comprises
the steps of: applying tension to a first strip of such film and
simultaneously applying tension to a second strip of such film to
move said film strips through the machine, applying a controlled
amount of solvent activator consisting of water and an additive to
preselected areas of at least one of said film strips to activate
and tackify the surface thereof before any part of the package is
formed but insufficient to reduce the strength of the film below
that needed to withstand the said tension forces applied to the
film, moving said first and second strips of film into sealing
alignment with each other by the continued application of tension
solely to the said film strips, pressing a portion of said first
and second strips of film together to form a seal between the two
strips of film and a packaging envelope open at one end thereof,
filling the package through the open end thereof, pressing a second
portion of said film strips together to seal the open end of the
package, and moving said package out of said machine by the
continued application of tension solely to said film strips.
39. A process for manufacturing packages of water-soluble film in a
machine of the type which includes an applicator for applying
solvent activator to the film to make it adhesive which comprises
the steps of: applying tension to a first strip of such film and
simultaneously applying tension to a second strip of such film to
move said film strips through the machine, applying a controlled
amount of solvent activator in the form of discrete droplets to
preselected areas of at least one of said film strips to activate
and tackify the surface thereof before any part of the package is
formed but insufficient to reduce the strength of the film below
that needed to withstand the said tension forces applied to the
film, moving said first and second strips of film into sealing
alignment with each other by the continued application of tension
solely to the said film strips, pressing a portion of said first
and second strips of film together to form a seal between the two
strips of film and a packaging envelope open at one end thereof,
filling the package through the open end thereof, pressing a second
portion of said film strips together to seal the open end of the
package, and moving said package out of said machine by the
continued application of tension solely to said film strips.
40. The process specified in claim 39 further comprising the step
of applying between 30 and 230 discrete droplets per linear inch to
said preselected areas of said film.
Description
This invention relates principally to a method and apparatus for
making a flexible package from a water-soluble and preferably
edible starch film.
Water-soluble starch film has been previously suggested as a
packaging material but it has not up until now enjoyed any measure
of commercial utility. One of the reasons for this is that
water-soluble starch film is not a true thermoplastic material and
it therefore cannot be sealed in conventional manner by heat and
pressure alone. The water-soluble starch film is perhaps a
pseudothermoplastic film in that it is flexible and can be softened
by heat and pressure but it cannot be sealed by heat alone because
the heated film when cool becomes brittle and the seal so readily
fractures that it is unsuitable in a commercial package.
This problem of sealing the water-soluble starch film has been
overcome in accordance with the present invention by means of a
solvent such as water which so activates and tackifies the surface
of the film that a perfectly acceptable commercial seal may be
formed by merely pressing the activated surfaces together to form a
cold weld seal in the package. If desired, moderate heat may be
employed along with the solvent activator in forming the seal in
the package.
The difficulty with a solvent activator is that it dissolves the
film or otherwise so destroys the tensile strength that the film
cannot withstand the tension and manipulation to which it is
subjected as it moves through a high-speed automatic packaging
machine. This difficulty was successfully overcome by manufacturing
the water-soluble starch film to certain specified physical
characteristics and by applying the solvent activator to the film
in such a controlled manner as to maintain the tensile strength
required for advancing the film through the high-speed packaging
machine.
In accordance with the present invention, the water-soluble starch
film must have a minimum tensile strength of at least about 500
p.s.i. as measured in conventional manner by the American Society
of Testing Materials 1967 Test No. D747--63. But strength alone is
not enough and the water-soluble starch film must also be flexible
and possess that attribute of body stiffness required for
manipulation in high-speed packaging machines. To this end, the
water-soluble starch film must have a minimum stiffness of about
2.5 grams as measured by a Handle-O-Meter test with a sample of
starch film 2 mils thick and 4 inches wide pushed into a one-half
centimeter slot in conventional manner. This Handle-O-Meter test is
described in Federal Specification UU--P--556 and as there
described, a sample of film of selected width is placed on a flat
plate over a slot. The film is then pushed down into the slot by a
bar and the force necessary to push the film into the slot is
measured on a strain gauge and reported in grams. A change in width
of the sample of a given starch film employed in the test will
change the reading on the strain gauge but the film will still have
a stiffness equivalent to that of the 4-inch sample referred to
hereinabove.
U. S. Pat. No. 3,243,308 describes an extrusion process for
preparing a water-soluble starch film with the above physical
characteristics. As described in this patent, the film may be made
with a mixture of a high amylose starch derivative mixed with
water. A plasticizer is preferably added to the mix to give better
control of the flexibility and strength of the extruded film. By
following the teaching of this patent, one skilled in the art of
starch chemistry will have no difficulty in manufacturing a
water-soluble starch film with the specified physical properties
required for carrying out the present invention. While extruded
high amylose water-soluble starch film is a preferred material, a
cast water-soluble starch film made in conventional manner to have
the specified physical properties may also be employed in the
present invention.
The application of solvent activator to the water-soluble film in a
controlled manner to seal the package is important for preserving
the tensile strength of the film at the level required to withstand
the stress of manipulation in the high-speed packaging machine.
Water-soluble starch film is extremely sensistive to water and a
change in room humidity may make it necessary to change the amount
of solvent activator in order to form an acceptable commercial seal
or to avoid dissolving the film to the point where it is so weak
that it will rupture in the machine. Additives such as gums,
dextrine or glycerine may be employed in the solvent activator to
combat change in room humidity but these additives do not eliminate
the need for controlled application of the solvent activator.
In accordance with the present invention, the solvent activator is
preferably applied to the film in the form of discrete droplets
which readily give the control required to insure that enough
tensile strength remains in the film in the activated area to
subject the film to high-speed manipulation and tension and yet be
sure that the film surface has been rendered sufficiently tacky to
achieve a high-strength cold weld seal between two or more strips
or folds of film. Preservation of the tensile strength of the film
by controlled deposition of discrete droplets of solvent activator
renders the film eminently suitable for use in a high-speed
packaging operation wherein tension is applied to the
solvent-activated film to move it relative to the packaging
machinery while the package is formed, filled and sealed in the
machine without rupture. The reason why the discrete droplets of
solvent activator are of particular advantage is not yet fully
understood but the currently favored view is that the deposition of
discrete droplets followed by a spreading of the activator on the
surface of the film from one droplet to another gives a very
precise control of the amount of activator applied to the film and
it tends to restrict objectionable solvent action of the activator
to the isolated spots of the droplets which in turn tends to
preserve the tensile strength of the film at the required level in
high-speed packaging operations. The spreading out of the droplets
of solvent activator on the surface of the film may take place at
the time the package is formed or prior thereto. These are
presently favored viewpoints but new and different reasons for the
above behavior may later be shown to account for the advantages
derived from this particular method.
Water-soluble starch film is generally stretched during manufacture
or otherwise given an internal stress orientation in at least one
direction. When this is the case, the amount of solvent activator
deposited on the water-soluble film may be readily controlled and
it may not be necessary to deposit the solvent activator on the
film in the form of discrete droplets. If an excess of solvent
activator is applied to the water-soluble starch film striations
appear on the surface of the film as a plurality of ridge lines and
valleys running in a direction generally parallel to the stress
orientation. Bubbles may appear as areas of relaxation wherein the
film in the area of activation appears to be loose when the film is
pulled tight. Why this occurs is not fully understood at the
present time but it is thought to be a function of overrelaxation
of stress in the film when too much activator is applied to the
film. As a result, the oriented water-soluble starch film has a
built-in warning system so that when striations or bubbles appear
too much activator has been applied. Of course, visual examination
of the finished package will show if enough activator has been
applied for a satisfactory seal.
For best results, discrete droplets of activator are deposited on
the film surface by a roll which has an etched or engraved surface.
The roll is rotated through a bath containing the activator
solution and the film is run against the roll under slight tension.
The roll deposits discrete droplets of activator on the surface of
the film in accordance with the etch pattern on the roll. The
etched roll is a conventional intaglio roll of the type used in
printing operations and the amount of solvent activator deposited
on the water-soluble film is determined by the screen rating of the
roll which is the standard for intaglio rolls that determine the
number and size of the depressions in the roll.
It has been found that for films ranging in thickness from one-half
mil up to about 5 mils, an etched roll having an etch spacing of
150 depressions per linear inch (150 screen) gave excellent
results, generally regardless of the thickness of the film. An
etched roll with a screen rating from about 30 to 230 may also be
used depending on the selected film and solvent activator at hand.
When using a roller having 150 depressions per linear inch to apply
water as the solvent activator to an area of about 3 square inches
out of a total area of about 8 square inches of film 2 mils thick
at about 50 percent relative humidity the weight of the film
increased about 5 percent and a satisfactory seal was formed.
In general, an adequate seal may be obtained if the solvent
activator increases the weight of the above-specified section of
film from about 2.0 percent to about 15 percent. It can be
appreciated however that as the thickness of the film is increased,
the amount of solvent activator applied to the film may also be
increased without objectionable loss in film strength and as
brought out above a change in humidity may also require that a
change be made in the amount of solvent activator applied to the
film. A change in the composition or the ingredients used in making
the starch film will also change the amount of solvent activator
which may be deposited on the film and it is therefore virtually
impossible to specify the exact amount of solvent activator to use
under all circumstances. In general, however, the amount of solvent
activator should be at least enough to tackify the film surface to
make it adhesive and the film should not be completely dissolved in
the solvent activator.
It is to be understood that the etch pattern on the surface of the
roller and the size of the depressions can be changed to deposit
more or less activator as desired in a particular application. The
amount of solvent activator applied to the film may also be changed
by varying the time of film contact with the roller. This is
preferably done by changing the angle of contact between the film
and roller. When the film is run tangent to the roll surface a line
contact is established which deposits a minimum amount of solvent
activator on the film surface. When the film forms a 90.degree.
angle in contact with the roller, the time of contact between film
and roller increases with a corresponding increase in the amount of
solvent activator deposited on the film. This feature may in some
applications eliminate the need to change rollers to different ones
having a smaller or larger depression in the etch pattern in order
to change the amount of activator deposited on the film.
In most packaging operations, it is contemplated that the etched
roll and supply roll of film will be driven at a constant speed to
eliminate any unnecessary application of tension to the film beyond
that required to advance the film through the packaging machine.
After the solvent activator has been applied to the film in the
desired pattern for forming the package, the film is advanced
through the selected high-speed packaging machine where the package
is formed, filled and sealed. One outstanding advantage of the
present invention is that the tensile strength of the water-soluble
film is maintained at the level required to withstand high-speed
manipulation experienced in forming the package and the film may be
drawn through the machine under tension and filled without the
necessity of special supports to prevent its rupture under stress.
While the present invention is of particular advantage in
connection with forming packages of water-soluble starch film, it
will be understood that the invention may also be utilized to form
packages from any known water-soluble film which does not include
starch as an ingredient thereof.
As used in the specification and claims, the term solvent activator
is intended to mean any liquid which is capable of exerting solvent
action on the water-soluble film to the extent that the surface of
the film is at least tacky and capable of cohering to itself or
adhering to another dissimilar surface. Water is the preferred
solvent activator but organic alcohols and other known solvent
adhesives may also be used and if desired additives such as glycol,
dextrine or gums may be added to the solvent activator.
Referring now to the drawings wherein various preferred embodiments
of the invention are shown and in which like numerals refer to like
parts:
FIG. 1 is a schematic view of an intermittent packaging machine
wherein a package is made from two strips of film.
FIG. 2 is a schematic view of a rotary (nonintermittent) packaging
machine wherein a package is made from two strips of film.
FIG. 3 is a schematic view of a packaging machine in which the
weight of the completed package is supported.
FIG. 4 is a schematic view of a packaging machine wherein the
package is formed from one strip of film.
FIG. 5 is a side view of a preferred form of applicator
assembly.
FIG. 6 is a front view of the preferred form of applicator
assembly.
FIG. 7 is a front view of an etched applicator roll.
FIG. 8 is an isometric view of another form of applicator.
FIG. 9 is an enlarged detail view of one form of the applicator
roll etch pattern.
Referring to FIG. 1, there is seen an intermittent packaging
machine 10. Two strips of film 11 are fed from storage rolls 12
under tension over idler rolls 13 by an applicator indicated
generally at 14 in a manner to be described hereinafter. Idlers 13
change the direction of film travel between the storage roll 12 and
applicator 14.
Referring now to FIGS. 5, 7 and 8, there is seen an applicator
indicated generally at 14 which has a positively driven applicator
roll 17 mounted therein. Applicator roll 17 pulls film from the
storage roll 12 in a manner to be hereinafter described. The
applicator roll 17 is preferably of the intaglio type and has an
etched surface 32. The positively driven applicator roll 17 rotates
in trough 15 and picks up solvent activator 16, preferably water
with or without an additive such as ammio gum, dextrine or
glycerine, in a plurality of depressions 32 termed "screen," which
depressions are preferably below the surface 33 of the roller 17
(FIG. 7). In the preferred applicator, there are between 30 and 230
depressions to the linear inch although 150 screen is most
preferable, generally regardless of film thickness.
The particular pattern of depressions shown on the roller 17 in
FIG. 7 is used to apply solvent activator to strips of film from
which small, square packages are to be made. However, any pattern
may be used depending on particular packaging needs.
As shown in FIG. 8, the particular pattern disclosed in FIG. 7 is
repeated twice on a modified roll and imprints a double pattern on
film 11 which is preferably a water-soluble starch film. The
pattern imprinted consists of a pair of longitudinal imprints 34,
and a pair of cross imprints 35 and 36. The applicator roll however
may have the pattern repeated any number of times or even have a
plurality of different patterns etched thereon.
The film 11 is drawn from storage roll 12 by positively driven
applicator roll 17 which deposits discrete droplets of solvent
activator on the surface of the film in accordance with the pattern
and screen rating 32 of the applicator roll. As the film is
manipulated by the packaging machine in its passage from the
applicator roller 17 to the various other parts of the machinery,
the droplets tend to spread out and run together either before or
during the time the solvent activated areas of the films are
pressed together to form a seal.
The applicator roll 17 is mounted on shaft 21, the shaft being in
turn mounted in a pair of bearing blocks 22. The bearing blocks 22
are slidably mounted in machined slots 24 in frames 23. Threaded
rods 26 are secured in each of the two bearing blocks 22 on either
side of applicator roll 17 and extend through holes in each of two
retainer plates 30 for a purpose described hereinafter. The
retainer plates 30 are rigidly affixed to frames 23. Springs 27 are
mounted coaxially on the threaded rods 26 between the retainer
plates 30 and a rotatable knurled nut 28. The knurled nut 28 moves
up or down the threaded nut 26 depending on which way it is rotated
to increase or decrease the length of springs 27. If the knurled
nut 28 is rotated so as to move it upwardly towards the retainer
plates 30, the spring 27 will be compressed. The springs 27 urge
the assembly of threaded nut 26, bearing blocks 22 and applicator
roll 17 against a doctor blade 31, the force urging the assembly
against the doctor blade being a function of the compressed length
of springs 27 which is a function of the position of the knurled
nut 28 against which the springs 27 act.
A second pair of knurled nuts 29 are rotatably mounted to the end
of the threaded rods 26 and bear against retainer plates 30.
Knurled nuts 29, when rotated, raise and lower the combination of
threaded rods 26 and bearing blocks 22 to accommodate varying size
applicator rolls 17. Therefore, by rotating the knurled nuts 29 to
raise the threaded rods 26, a larger size applicator roll 17 can be
accommodated. The knurled nut 28 can then be rotated to change the
compressed length of springs 27 to change the force exerted by the
applicator roll 17 on doctor blade 31, to any desired level.
In the present application, the level of solvent activator 16 in
the trough 15 is of no importance. All that is necessary is that
the etched surface 32 of applicator roll 17 be below the surface of
solvent activator 16 in trough 15 to assure that the etched surface
32 of the applicator roll 17 will always be picking up solvent
activator in the etched areas. Doctor blade 31 scrapes the surface
of the applicator roll 17 as the applicator roll rotates to confine
solvent activator to only the etched areas of the applicator roll
17.
The pressure rolls 19 and 19a (FIG. 5) are mounted on pressure bars
37. Pressure roll 19a has its bearing 38 spring loaded downwardly
by spring 39 to apply pressure to applicator roll 17. Pressure roll
19, also mounted to pressure bars 37, is positionally fixed
relative to the pressure bars. The pressure bar 37 is pivotally
mounted to side frame 23 through the shaft of idler roll 13a.
Pressure rolls 19 and 19a apply pressure to the film 11 as it
passes between the pressure rolls 19, 19a and applicator roll 17 to
keep the film in contact with the etched surface of roller 17 and
are adjustable with respect to the applicator roll so that the
angle of contact of film to roller can be varied as described
hereinafter.
Mounted to pressure bars 37 at shaft 13a is a bellcrank lever 40.
The bellcrank lever 40 is pivotally mounted to a piston 41 which
forms a part of air cylinder assembly 42. When the air cylinder is
activated so as to move the piston 41 rightwardly as in FIG. 5, the
bellcrank lever 40 is pivoted clockwise about shaft 13a carrying
pressure bar 37 with it in a clockwise direction to lift pressure
rolls 19 and 19a from the applicator roll 17 to allow the film 11
to move out of contact with the applicator roll 17. This is of
particular advantage when, for any reason, the packaging operation
is stopped because if the now stationary film were allowed to
remain in contact with the applicator roll 17 for too long, the
solvent activator carried therein would probably dissolve the
film.
Piston 41, when moved leftwardly to cause bellcrank lever 40 to
rotate in a counterclockwise direction, causes pressure bar 37 to
also rotate in a counterclockwise direction about shaft 13a to
cause pressure roll 19a to ride up against the pressure of spring
39 to press film 11 against applicator roll 17. The
counterclockwise movement of pressure roll 19 is continued to
increase the wrap, or angle of contact of film 11 to applicator
roll 17 until the pressure roll 19 also contacts applicator roll 17
at which point there can be no further increase in the angle of
contact.
Functionally, control over the angle of contact of film to
applicator roll for a given constant speed of rotation of the
applicator roll allows an increase or decrease in dwell time, i.e.,
the amount of time a particular section of the film is in contact
with the applicator roll. The longer the film is in contact with
the applicator roll, the greater the amount of solvent activator
absorbed by the film surface and vice versa. Therefore, the
applicator roll 17 can be used to activate film having different
thicknesses without changing to an applicator roll having a
different screen size to vary the amount of solvent activator
deposited on the film.
I have found it preferable to apply drag to the film storage rolls
12 to prevent the film from being indiscriminately pulled from the
storage roll by the rotating applicator roll 17. To this end,
storage roll 12 is mounted on a pair of hubs 43 and 43a. Hub 43a is
held in place by a pair of thumb nuts 44 mounted to studs 44a. The
studs 44a are at their ends opposite the thumb nuts 44 mounted to a
brake hub 45. An adjustable brake disc 46 is urged against shaft
43d and applies drag to the storage roll 12 by applying pressure to
brake hub 45. The amount of drag applied can be varied by
adjustment screw 47 which is mounted on shaft 43d. The adjustment
screw 47 has a threaded portion 48a in brake hub 45. Mounted
between the head of the adjustment screw 47 and brake disc 46 is a
spring 47a which applies force to brake disc 46 when the adjustment
screw 47 is tightened, thereby increasing the drag force between
brake disc 46 and brake hub 45 to increase the amount of drag
applied to the storage roll 12.
The film from the storage roll 12 is guided by side plates 43b and
the whole assembly may be moved leftwardly or rightwardly to center
the storage roll by adjustment nut 43c which is mounted to a
nonrotating shaft 43d on which the whole storage roll assembly is
mounted.
Applicator roll 17 is driven from the packaging machine drive (not
shown) which also drives the machine seal bars 56 and 58 as
described hereinbelow, through sprocket drive assembly 49.
Interposed between sprocket drive assembly 49 and applicator roll
17 is a plurality of gears indicated by the rectangular box 50
which houses a differential assembly (not shown). Attached to
floating shaft 21 is a plurality of gears 51 which transfer drive
motion from the differential assembly 50 to the floating shaft 21
which in turn transfers the drive motion to applicator roll 17. The
applicator roll 17 is driven off the machine drive in order to
supply solvent activated film to the packaging machine at a rate
consistent with the speed of packaging. Therefore, if the packaging
speed is increased, so is the speed of rotation of the applicator
roll 17.
The differential assembly provides a running register control
whereby applicator roll 17 can be rotationally advanced or retarded
without increasing its speed of rotation with respect to the
packaging machine to bring solvent activated film areas into
sealing alignment with the machine seal bars so that the seal bars
do not operate on unactivated film areas. This is done during
machine operation and does not require that the machinery be
stopped.
Returning now to the embodiment of FIG. 1, the film 11 passes from
the driven applicator roll 17 to a dancer bar 52. Dancer bar 52 is
used to couple the applicator assembly to intermittent packaging
machinery and is not necessary on rotary or any
nonintermittent-type machinery. The dancer bar 52 is mounted to a
spring 53 which is in turn mounted to any stationary portion of the
machine assembly. The operation of the dancer bar will be
hereinafter described.
From the dancer bar, the activated film 11 is fed to a packaging
machine indicated generally at 10. The two strips of film 11 are
passed in close proximity to a fill tube 54. Rolls 55 bring the
film strips 11 in close to the fill tube 54. From the rolls 55, the
film is fed between a pair of side seal bars 56 which move in the
direction indicated by the arrow 57. The side seal bars 56 make the
longitudinal seals along imprints 34 (FIG. 8) by applying pressure
to the two strips of film 11 with or without heat to cause the two
strips of film to weld together.
After the side seals along imprints 34 (FIG. 8) have been made, the
film strips advance to the next station where a first cross seal
along imprints 36 (FIG. 8) is made by cross seal bars 58. Cross
seal bars 58 move in toward the film strips 11 as indicated by
arrow 59 to apply pressure to the film with or without the
application of heat to effect the cross seal along imprints 36.
At this point, fill tube 54 is operated to release a predetermined
amount of material with which the now partially sealed package
envelope is to be filled against the first cross seal along
imprints 36. The cross seal bars 58 then, either conjointly with
the filling operation or before or after the filling operation,
move downwardly as indicated by arrows 60 while still applying
pressure to the film to pull the now partially completed package
envelope 61 under tension to the position indicated by the dotted
outline of cross seal bars 58. At this point, cross seal bars 58
release their pressure and move outwardly away from the film and
then upwardly to the original position at which point the process
begins all over again. However, the second cross seal along
imprints 35 (FIG. 8) that is made by the cross seal bars 58 as the
closing seal to complete the package 62 also serves as the first
cross seal for the next package. The packages are then advanced
under tension out of the packaging machine and may be severed from
preceding packages by reciprocating knives 69.
Because the packaging machine operates intermittently, the film is
intermittently loaded in tension during the packaging operation.
This is especially true because the applicator roll 17 is driven at
a constant rate of speed so that as the film advance stops to allow
the machine to make the side seals along imprint 34, applicator
roll 17 is still feeding film which will tend to form in a loose,
looplike pattern. When film advance is resumed, the film slack
would be quickly removed and the film shock loaded. In the present
invention, as the cross seal bars pull the package 61 downwardly,
the dancer bar is moved in clockwise rotation about idler 13 to its
dotted line position. The clockwise movement of the dancer bar 52
extends the spring 53 so that when the cross seal bars 58 stop
their downward travel, the dancer bar begins to rotate in a
counterclockwise direction to take up the slack in the film caused
by the constant film feed rate of the applicator roll 17. The
dancer bar therefore keeps constant tension on the film and
eliminates undesirable loop formation and shock loading of the
film.
Referring now to FIG. 2, there is shown a typical rotary packaging
process. The applicator assembly 14 and storage roll and brake
assembly as described for FIG. 1 are exactly the same for this and
subsequent processes described herein and for the sake of brevity
will not be redescribed.
In this process, film 11 is fed from storage roll 12 past idlers 13
to applicator assembly 14 where solvent activator is applied to the
film as previously described. From the applicator 14, the
now-activated film 11 is run unsupported across idlers 63 under
tension past fill tube 54 as described below. The activated film 11
is brought into close proximity to the fill tube 54 and into
sealing alignment with each other by sealing rolls 64 which are
positively driven. Sealing rolls 64 are driven at a constant rate
of speed that is preferably slightly faster than the rate of speed
that applicator roll 17 is driven at. This difference in speeds
creates a small, controllable amount of tension in the film and
assures that the film will not form a loop between the applicator
roll 17 and the sealing rolls 64.
In a particular package that is formed by two sets of seals to form
a rectangularly sealed package, the seal members 64 form a
continuous longitudinal side seal by applying pressure with or
without the addition of heat to cause the two strips of film to
cohere.
From seal members 64, the now partially formed package is run to a
second set of seal members 65. Seal members 65 are, similarly to
seal members 64, positively rotated in the direction of film travel
at a constant speed equal to or preferably somewhat faster than the
speed seal members 64 are being rotated at to keep tension on the
film.
Seal members 65 are generally cam shaped so as not to apply
pressure to the film continuously and are formed in the shape of
the area to be sealed, i.e., pressure is not applied by seal
members 65 to the film when an unactivated portion of film is
passing through the seal members. Therefore, seal members 65
contact the film intermittently but, because they are rotating in
the direction of film travel, do not cause any undue intermittent
shock loading of the film other than the shock that would be
present due to the preferably slightly faster speed of the seal
members 65. The cross seal bars 65 are also relieved in their
central portions to allow the filled, partially sealed package
envelopes to pass unobstructed between the seal bars 65.
Seal members 64 have reduced diameters in their central portions as
indicated by the dotted lines whereby the diameter of the seal
members 64 in their central portions is reduced so the central
portion of the film strips pass unsealed to seal members 65. The
fill tube 54 extends downwardly between the activated film strips
through the reduced central portion of the seal member 64.
As seal members 65 rotate, a first cross seal along imprints 35
(FIG. 8) is made against which fill tube 54 releases a
predetermined amount of package fill. The filled package envelope
is now completely unsupported and, while in this condition, is
sealed again by seal members 65 to form a second cross seal along
imprints 35 (FIG. 8) to complete the package. The second cross seal
along imprint 35 is also the first cross seal for the next
subsequent package.
An alternate form of seal member is indicated at 66 wherein those
portions of the seal member not necessary to the sealing operation
have been removed to form a simple, cross-shaped block. It is
contemplated that any form of seal member may be used to apply
pressure to complete the cross seals, with or without the addition
of heat.
Positioned below the seal members 65 is a pair of draw rolls 67.
Draw rolls 67 are positively driven and rotate in the direction of
package travel to pull the completed packages under tension away
from the seal members 65. The draw rollers are of less diameter at
their central portions as indicated by the dotted line 68 so as not
to apply any pressure to the portion of the package containing the
fill material. However, it is contemplated that in some
applications the machine can be operated without the use of draw
rolls 67 since the seal members 65 force the packages downwardly as
a natural result of their rotation.
Positioned below the draw rolls 67 is a cutting knife 69 wherein
each half thereof reciprocates towards and away from the finished
packages to sever them along the cross seal. However, it is
contemplated that a cutting knife need not be used since in some
applications it is desirable to maintain the integrity of the
string of packages.
Referring now to FIG. 3, there is shown another process for making
packages from water-soluble film. Basically, the applicator 14 is
the same as that described above and for brevity, will not be
redescribed. In this process, film 11 is fed under tension from
storage roll 12 to applicator 14 which applies a controlled amount
of activator to the film in a predetermined pattern as described in
the previous embodiments. The activated film 11 is then fed to
endless belt 70 and is directed along the surface of the endless
belt. Fill roll 54 rotates in fill reservoir 54a and releases a
predetermined amount of package fill on to the moving film. From
this point the film carrying the package fill is moved to another
station in which a second strip of film 11', which may or may not
be activated, is brought into sealing alignment with film strip 11.
A side seal is then made by rotatable seal member 71 by applying
pressure with or without heat to the two strips of film 11, 11'
against endless belt 70, which is supported by rotatable support
72. Rotatable support 72 and seal members 71 rotate continuously
and conjointly to move the partially completed package envelope to
another sealing position on the endless belt where rotatable seal
member 73 applies pressure against rotatable support 74 via the
endless belt to form the final cross seal and complete the package.
The rotatable seal members 71, 73 are similar in structure and
function to the seal members 64 and 65 of FIG. 2. However, it is
contemplated that seal members 71, 73 may be composed of two sets
of seal members, one to make the side seals and one to make the
cross seals similar to those shown in FIG. 1. It is further
contemplated that the seal member 71 be eliminated and the seal
member 73 apply the side seals as well as the cross seals simply by
making the edges of seal member 73 circular and of greater diameter
than the inner portion of the seal member so that the edges contact
the film to make the side seals as described above and making the
inner portion of the seal member 73 in the form shown in the
drawing whereby the side and cross seals may be made by only one
seal member. It is also contemplated that advance of the completed
package out of the machine be accomplished by a plurality of draw
rolls instead of solely by the seal member 73.
FIG. 4 depicts another type of packaging machine wherein the
package is to be formed from a single strip of film. This
particular process concerns itself with making an unsupported
package sealed on at least three sides but it is contemplated that
the single strip of film may also be used to form a tube therefrom
and sealed only axially on the circumference thereof.
In the process of FIG. 4, film 11 is fed from storage roll 12 to an
applicator indicated generally at 14 and is similar to the process
of the previously described embodiments and will not be
here-described again. From the applicator 14, the film is run
between a pair of idler pins 73, which fold the film in upon
itself. From the idler pins 73, the folded film passes between a
pair of positively driven seal bars 74 which vertically seal the
film. The seal bars 74 also intermittently pull the film 11 under
tension from the positively driven applicator roll 17. To prevent
loop formations in the film, idler roll 80 is movable in the
direction of the arrow 80a and performs the function of the dancer
bar illustrated in FIG. 1. The structure of the dancer bar system
in this embodiment is similar to the FIG. 1 embodiment and for the
sake of brevity and compactness will not be here redescribed or its
structure reshown. The vertical seal made by seal bars 74 only
extends to a point slightly below the open end of the partially
completed package envelope. One or more fill tubes 75 is used to
fill the partially sealed package envelope and the neck 76 of the
fill tube 75 preferably extends below the open end of the package
envelope to keep the package envelope open. The bottom edge of the
folded film may be sealed if this is so desired by applying
pressure with or without the application of heat to the film before
filling the package envelope.
From the seal rolls 74, the folded film advances to sealing station
77 which comprises a pair of intermittent sealing members 78 which
applies the final seal to the package at 79. The seal members 78
rotate in conjunction with the seal members 74 and are intermittent
to allow the film advance to stop so that the package envelope can
be filled. Seal bars 78 can also be similar in structure and
function to seal members 58 of FIG. 1. Also, pulling force for
moving the final package out of the machine may be provided by
separate draw rolls (not shown) in addition to the pulling force on
the film occasioned by the seal rolls 78. It is also contemplated
that the process need not be intermittent but can be rotary if the
seal bars of the embodiment of FIG. 2 are used instead.
All the processes described herein are unsupported packaging
operations in which the film is required to support the weight of a
completed package or the force of a completed package being moved
under tension away from the sealing portion of the packaging
operation. Any water-soluble film can be used as long as the film
is manufactured to have a minimum tensile strength of 500 p.s.i.
and a maximum 2.5-gram stiffness factor as set forth above and is
activated by applying controlled amounts of solvent activator to
the film as set forth hereinabove. It is also contemplated that any
activator having solvent action on the film can be used, including
glues.
It will be understood that it is intended to cover all changes and
modifications of the preferred embodiments of the invention, herein
chosen for the purpose of illustration, which do not constitute
departures from the spirit and scope of the invention.
* * * * *