Method for attaching a flexible inner bag to the inside of a squeezebottle

A method for scaling a flexible inner bag inside a squeezebottle so that the flexible inner bag will invert in order to dispense viscous fluids. The method is particularly useful in single-piece squeezebottles which have a small ratio of discharge opening cross-section to body cross-section. In practicing the present invention, a flexible inner bag has heat-activated adhesive stripes applied to the upper half of its exterior. The flexible inner bag is inserted into a squeezebottle through the discharge opening and then expanded inside the squeezebottle by compressed air. After the flexible inner bag is fully expanded, and with pressure applied to the inside of the flexible inner bag, heat is applied either to the inside of the bag or to the outside of the squeezebottle by hot air, steam, radiation, or induction heating of metal particles in the adhesive. The adhesive is heat-activated and the upper half of the flexible inner bag is thereby attached to the inner side wall of the squeezebottle.

FIELD OF THE INVENTION 
The present invention relates to processes for attaching a flexible inner 
bag to the inside of a squeezebottle dispenser, and more particularly to 
processes for inserting and attaching a flexible inner bag through a 
discharge opening of a single-piece outer container wherein the discharge 
opening is smaller in dimension than the cross-section of the container 
body. 
BACKGROUND OF THE INVENTION 
Squeezebottle dispensers having fluid-containing, flexible inner bags 
within them are common in the art. When a squeezebottle dispenser is 
squeezed, fluid is forced from the flexible inner bag through a discharge 
opening at the top of the dispenser. Valving in the dispenser enables air 
to be compressed within the squeezebottle during squeezing, but valving 
then allows air to vent into the bottle to replace the dispensed fluid 
after the squeezebottle is released. Repeated squeezing cycles cause the 
flexible inner bag to collapse around the fluid within the squeezebottle 
as the flexible inner bag empties. 
A problem with such dispensers is that a flexible inner bag tends to 
collapse most quickly near its discharge opening. This is believed to be 
due to higher velocity fluid flow near the discharge opening causing lower 
static pressure there. Fluid flow may be choked off from the rest of the 
flexible inner bag if the flexible inner bag collapses prematurely near 
the discharge opening. To correct this problem, the manner in which the 
flexible inner bag can collapse is generally controlled. For example, a 
flexible inner bag may be designed to collapse radially about a perforated 
diptube connected to the discharge opening of the squeezebottle. In some 
circumstances, for example, when the fluid is highly viscous like 
toothpaste, diptubes generally provide too much resistance to fluid flow 
through them. For such fluids, which have viscosities great enough that 
they cannot flow under gravity, another collapse control approach is often 
used. That is, a flexible inner bag is affixed to the upper half of the 
inside of a squeezebottle so that the flexible inner bag can collapse by 
inverting axially toward the discharge opening. Flexible inner bag 
inversion offers minimum flow resistance. 
For squeezebottle dispensers having flexible inner bags which invert toward 
the discharge opening, there is often a construction problem involved with 
inserting and affixing the flexible inner bag inside the squeezebottle. 
Such affixing usually involves heat sealing. The finish of the 
squeezebottle usually has a discharge opening smaller in circumference 
than the body of the squeezebottle so that the finish may later be capped 
with a reasonably sized closure. If the flexible inner bag is inserted 
into the squeezebottle from a small diameter discharge opening, it is 
difficult to insert a heat sealing tool into the flexible inner bag to 
seal the flexible inner bag to the upper half of the squeezebottle. A 
sealing tool would be expected to expand to press the flexible inner bag 
against the inner side wall of the squeezebottle. A reliable, high speed 
method for affixing a flexible inner bag to the inside of a squeezebottle, 
using an expanding tool, has been unavailable in many cases. 
To avoid this problem packagers have resorted to a two-piece squeezebottle 
construction with an open bottom so that a flexible inner bag can be 
installed from a large opening in the bottom of the squeezebottle. After 
flexible inner bag installation, a bottom piece is sealed to the 
squeezebottle to close it. An example of this construction is disclosed in 
U.S. Pat. No. 4,842,165 to Van Coney. Van Coney's squeezebottle dispenser 
has a fluid-containing bag permanently sealed to the top and to the 
midpoint of the inside of a squeezebottle so that the fluid-containing bag 
inverts to dispense viscous fluid. The method securing the flexible inner 
bag to the squeezebottle is fusion welding, using a heated tool from 
inside the open bag. The bag is filled after sealing it to the container 
side wall. Closing the bag after filling may be another slow and difficult 
process. 
For high speed filling and reduced part handling, it is most beneficial to 
have single-piece squeezebottles which can be filled from the discharge 
opening. Also, greater bottle shape flexibility is available with 
single-piece squeezebottles than with multiple piece constructions similar 
to Van Coney's. What is needed, however, is a bag-to-squeezebottle 
connection method which does not require the use of an expandable heated 
tool. 
Others have used adhesives to affix bags inside containers. For example, 
U.S. Pat. No. 4,154,366 to Bonerb discloses an outer bag with an 
expandable liner having pressure-sensitive adhesive spots to secure the 
liner to the inside of the outer bag. The liner is inflated to expand it 
against the inside of the outer bag. The adhesive spots are on the top, 
sides, and bottom surfaces of the liner. 
The problem with contact adhesives on a bag placed inside a squeezebottle 
is that they interfere with inserting and expanding the bag inside of the 
squeezebottle. When a flexible inner bag is inserted into the discharge 
opening of a single-piece squeezebottle, the bag has to be folded or 
partially collapsed to go through the opening. Then it has to be expanded 
inside the bottle before it can be bonded to the inside of the bottle. 
Expansion may be hindered by contact adhesives bonding bag folds together. 
The expansion process also involves a certain amount of sliding between 
the flexible inner bag and the inner side wall of the squeezebottle, 
requiring a low coefficient of friction. Contact adhesives generally have 
a high coefficient of friction. 
Induction sealing plastic parts together by heating metal embedded in one 
of the plastic parts, and by heating metal components which clamp the 
plastic parts together, are old in the art. Heat is developed by 
generating a high frequency oscillating magnetic field near the metal. 
Depending on the metal, either eddy current losses or magnetic hysteresis 
losses are believed responsible for heating the metal. Heat from the metal 
is then conducted through the plastic parts to their sealable interface. 
Plastic melting occurs from the conducted heat. If the plastic materials 
are compatible and sufficient pressure is applied, the plastic parts can 
be fusion welded together. The great benefit of the induction heating 
process is that heat can be quickly generated so that high production 
rates can be achieved. 
Processes for sealing webs using induction sealing are old in the art. For 
example, U.S. Pat. No. 3,461,014 to James discloses a process in which 
ferrous oxide particles small enough to be mixed with conventional 
printing ink are printed onto a substrate. The substrate and web are 
combined and passed through a magnetic induction field to heat the ferrous 
oxide particles between the substrate and web. Then the web and substrate 
are passed through a pair of "squeeze rollers" to generate sufficient 
pressure to seal the webs together. 
SUMMARY OF THE INVENTION 
In practicing the present invention, the method for attaching a flexible 
inner bag to an inner side wall of a single-piece squeezebottle comprises 
the steps of constructing a flexible inner bag having an exterior surface 
and having adhesive stripes on the exterior surface of the flexible inner 
bag, inserting the flexible inner bag through a squeezebottle discharge 
opening and into the body of the single-piece squeezebottle, expanding the 
flexible inner bag inside the body of the single-piece squeezebottle, 
closing the single-piece squeezebottle in a substantially air-tight 
manner, and activating the adhesive on the exterior surface of the 
flexible inner bag, after the bag has been expanded, while pressurizing 
the flexible inner bag through the passage in the rigid fitment. By this 
method the exterior surface of the flexible inner bag is affixed to the 
inner side wall of the single-piece squeezebottle. 
In one embodiment of the present invention, the adhesive activating step 
includes circulating a compressed, heated gas into the interior of the 
flexible inner bag in order to conduct heat through the flexible inner bag 
to activate a heat-activated adhesive, and to simultaneously apply 
sufficient pressure against the flexible inner bag in order to seal it to 
the inner side wall of the squeezebottle. The compressed, heated gas may 
be hot air or steam. 
In another embodiment of the present invention, the adhesive activating 
step includes radiating heat onto the outside of a squeezebottle. The 
squeezebottle conducts heat to a heat-activated adhesive pressed against 
its inner side wall. Compressed air is introduced into the bag 
simultaneously to apply sufficient pressure against the flexible inner bag 
to seal it to the inner side wall of the squeezebottle. 
In still another preferred embodiment of the present invention, the 
adhesive activating step includes induction heating a heat-activated 
adhesive from outside of the single-piece squeezebottle. The adhesive has 
metal particles therein for heat activation. Compressed air is introduced 
into the bag simultaneously to apply sufficient pressure against the 
flexible inner bag to seal it to the inner side wall of the squeezebottle. 
In yet another preferred embodiment of the present invention, for those 
adhesive heat-activating sources external to the squeezebottle, the step 
of generating pressure inside the bag comprises the exposure of the 
squeezebottle with expanded bag therein to a higher than atmospheric 
pressure environment, followed by plugging the passage in the rigid 
fitment to maintain the higher than atmospheric pressure in the bag, and 
then removing the squeezebottle from the higher than atmospheric pressure 
environment before heat activating the adhesive.

DETAILED DESCRIPTION OF THE INVENTION 
Referring now to the drawings, and more particularly to FIG. 1, there is 
shown a first preferred embodiment of the present invention, which is a 
squeezebottle dispenser constructed by the method of attaching a flexible 
inner bag to the inside of a squeezebottle, and is it generally indicated 
as 10. Squeezebottle 10 has body 12, finish 14, and shoulder 16. Connected 
to shoulder 16 is vent valve 18. Vent valve 18 may be a duckbill valve, 
for example, which is oriented to allow air into the squeezebottle when it 
is released, but which prevents air escaping the squeezebottle when it is 
squeezed. Alternatively, vent valve 18 may be located at the bottom of 
squeezebottle 10. There are many alternative vent valve constructions 
known in the art besides duckbill valves. 
Finish 14 has a discharge opening, not shown. Plugging the discharge 
opening in a substantially air-tight manner is a rigid bag fitment 20. 
Rigid bag fitment 20 has a passage 22 therethrough which is in fluid 
communication with the interior of a fluid-containing, flexible inner bag, 
not shown in FIG. 1. 
FIG. 2 discloses a preferred flexible inner bag construction. Connected to 
rigid fitment 20 is flexible inner bag 24, preferably made from 
transparent flat film 26. The bottom surface of rigid fitment 20 is 
annular where it surrounds passage 22 extending through rigid fitment 20. 
The bottom surface of rigid fitment 20 is preferably heat sealed to film 
26. Ultrasonic scaling and hot die scaling have both been used 
successfully for such heat sealing when both are made of compatible 
materials. Alternatively, film 26 could be adhesively scaled to rigid 
fitment 26. A continuous annular seal is required. 
A hole, not shown, FIG. 2 is preferably cut into film 26 within the annular 
heat seal so that rigid fitment 20 will have fluid communication with the 
interior of the flexible bag to be formed from film 26. The hole is 
preferably a cross-shaped slit punched from the film side into passage 22 
of rigid fitment 20. The slit results in no scrap pieces to be accumulated 
during the process, yet provides a hole when the slit flaps bend. 
Film 26 is then folded downward where it connects to rigid fitment 20. The 
width of the fitment connection generates a top end 28 of the flexible bag 
yet to be formed. Once flat film 26 is folded, edges 30 of flat film 26 
are fin-sealed together, preferably by heated dies, to form the closed 
flexible inner bag 24. Fin-sealed edges 30 are angled at their corners, 
preferably at 30.degree. to 45.degree. to the vertical axis of the bag, 
depending on the shape of squeezebottle body 12. The angled corners are 
beneficial to the steps of inserting and expanding flexible inner bag 24 
as it is installed in squeezebottle 10. Some bag volume is lost; however, 
the reliability of bag expansion is greatly improved by having angled 
corners. 
Either before or after forming flexible inner bag 24, adhesive stripes 32 
are bonded to the exterior surface of flat film 26 so that stripes 32 
preferably extend from the middle upward toward top end 28 of flexible 
inner bag 24. There are many alternative configurations available for 
adhesive stripes 32. Stripes 32 could be spots, arcs, or lines at 
different angles. However, since stripes 32 generally add stiffness to the 
portions of flat film 26 to which they are bonded, and since flexible 
inner bag 24 is usually folded along lines parallel to the vertical axis 
of the bag for bag insertion purposes, the preferred orientation of 
adhesive stripes 32 is also parallel to the vertical axis of the bag to 
facilitate bag folding. 
FIG. 3a shows additional features of squeezebottle 10. Rigid fitment 20 has 
a flange 34 and an air vent slot 36 spaced away from flange 34. Rigid 
fitment 20 fits tightly into finish 14 of squeezebottle 10, plugging a 
discharge opening 38. Slot 36 allows air to vent from squeezebottle 10 
when rigid fitment 20 is partially inserted into finish 14, while flexible 
inner bag 24 is expanded inside squeezebottle 10. After bag expansion, 
rigid fitment 20 is driven fully into finish 14 until stopped by flange 
34. Discharge opening 38 is thereby closed in a substantially air-tight 
manner. 
The preferred process for installing flexible inner bag 24 is in accordance 
with the teachings of commonly assigned U.S. Pat. No. 5,227,015, issued to 
Brown et al. on Jan. 11,1994, which is hereby incorporated herein by 
reference in its entirety. Brown et al. uses a converging funnel with 
angled plows to gather and fold a flexible inner bag as it is pushed 
through a funnel by a spring-loaded plunger. The plunger extends through a 
central passage of a rigid fitment to the bottom of the bag. Brown et al. 
uses compressed air to expand the flexible inner bag inside a container. 
In the present invention flexible inner bag 24 must be fully expanded 
inside squeezebottle 24 before adhesive stripes 32 may be activated to 
affix bag 24 to an inner side wall of body 12 of squeezebottle 10. After 
insertion of flexible inner bag 24 in the present invention, air or steam 
is injected into bag 24 to force the bag to expand inside squeezebottle 
10. 
Flexible inner bag 24 has an upper half 40, a bottom half 44, and a midline 
46. Midline 46 is defined by the lowermost edges of adhesive stripes 32. 
FIGS. 3a, 3b, and 3c show the sequence of events after flexible inner bag 
24 is expanded inside squeezebottle 10. First, as shown in FIG. 3a, upper 
half 40 of flexible inner bag 24 is affixed to squeezebottle 10 at 
adhesive stripes 32. Then, as shown in FIG. 3b, flexible inner bag 24 is 
filled with a fluid 42 through passage 22 of rigid fitment 20. Finally, as 
shown in FIG. 3c, repeated squeezing of squeezebottle dispenser 10 causes 
flexible inner bag 24 to empty and invert. That is, bottom half 44 of 
flexible inner bag 24 rises as fluid 42 is dispensed. Bag 24 turns inside 
out about midline 46. Bottom half 44 rises inside upper half 40. 
Air is vented into the squeezebottle by vent valve 18 as the bag inverts. 
If vent valve 18 is located in shoulder 16 of squeezebottle 10, adhesive 
stripes 32 must be intermittently spaced so that air may pass between them 
to below midline 46. If vent valve 18 is located at the bottom of 
squeezebottle 10, there would be no such requirement for intermittent 
spacing. 
One alternative for affixing the upper half of flexible inner bag 24 to the 
inner side wall of body 12 of squeezebottle 10 is hot air and/or steam 
circulated to conduct heat to the inside of the bag or to the outside of 
the bottle in order to activate a heat-activated adhesive. Heat is 
conducted through either tile bag or the squeezebottle to the adhesive. 
Another alternative is radiation heat from a probe placed inside the bag or 
from a source placed outside the bottle in order to activate a 
heat-activated adhesive. Typically infra-red radiation is preferred. Heat 
radiates to the bag or to the bottle and is then conducted therethrough to 
the adhesive. 
Still another alternative is magnetic induction heating of a heat-activated 
adhesive which has had metal particles added to it. An induction field may 
be created inside of the bag or outside of tile squeezebottle, depending 
on size limitations for the magnetic induction coil. The magnetic field 
heats the metal particles and they conduct heat to the adhesive. In this 
alternative heat doesn't have to be conducted through the bag or the 
bottle. 
In each these alternatives, the adhesive is activated at a lower 
temperature than the melting temperature of flexible inner bag 24 and 
squeezebottle 10. Activation occurs when the adhesive either melts or 
becomes tacky enough to wet the surface of the inner side wall of the 
squeezebottle and adhere to it. A lasting bond occurs between the bag and 
the inner wall of the squeezebottle in the presence of pressure forcing 
them together. 
In a particularly preferred embodiment of the present invention, steam at 
about 250.degree. F. is blown into bag 24 and allowed to escape so that 
less than 5 psig pressure is built up inside the bag. Heating occurs for 
less than 30 seconds in order to activate adhesive stripes 32 to bond bag 
24 to inner side wall of squeezebottle body 12. 
Bag 24 is preferably made from low density polyethylene film. Squeezebottle 
10 is preferably made of high density polyethylene by an injection blow 
molding process. It is shaped similar to a 6 oz. Oil of Olay Beauty 
Fluid.RTM. bottle, a Trademark of The Procter & Gamble Company of 
Cincinnati, Ohio. Body 12 has an oval cross-section with a major axis of 
71 mm, a minor axis of 35.6 mm, and a height of approximately 107.7 mm. 
Squeezebottle 10 has a standard 24 mm finish 14, which has a discharge 
opening 38 having a diameter of 18.8 mm. Bag 24 has an injection molded 
rigid fitment 20 made of low density polyethylene. The fin-sealed edges 30 
have a width of approximately 1.6 mm. The flat width of bag 24 is 92 mm 
and the height of the flexible inner bag is 118 mm. The bag dimensions are 
slightly larger than the inner dimensions of the bottle in order to fill 
the bottle when expanded. 
Adhesive stripes 32 are preferably made of 3M Jet-melt #3748-TC hot melt 
adhesive, made by 3M Corp., of St. Paul, Minn. The softening point of the 
adhesive is well below that of the bag and bottle materials in order that 
the adhesive become tacky at the interface between bag and bottle, but 
that the bag and bottle surfaces experience minimal softening. Adhesive 
stripes 32 are spaced about 19 mm apart, are about 3 mm wide, and are 
about 19 mm long. They are applied to flat film 26 by a hand held 3M 
Polygun TC hot melt applicator, made by 3M Corp., of St. Paul, Minn. 
Alternatively, for magnetic induction field heat activation, adhesive 
stripes 32 are made of the same adhesive, but with ferrous oxide particles 
mixed in. The percent by weight of particles in the adhesive, and the 
intensity of the induction field, determine the time of heating required 
to melt the adhesive. An induction field can be produced by a circular 
copper coil, commonly known in the art, into which squeezebottle 10 is 
centered without touching the coil. The coil may be cooled by circulating 
water and powered by an RF generator, such as model no. T53-KC-SW, made by 
the Lepel Co. of New York, N.Y. 
When the adhesive heat-activating source is external to the squeezebottle, 
pressurizing the inside the bag for scaling the bag to the inner side wall 
of the squeezebottle can be accomplished by first exposing squeezebottle 
10 to a higher than atmospheric pressure environment, such as in a 
pressure chamber, not shown. This step is followed by plugging passage 22 
in rigid fitment 20 to maintain the higher than atmospheric pressure in 
bag 24, and then by removing squeezebottle 10 from the higher than 
atmospheric pressure environment before heat activating the adhesive. 
After heat-activation, the plug, such as an ordinary rubber stopper, may 
be removed from passage 22 to release the pressure from bag 24. 
The key is to generate a higher pressure inside the bag than exists outside 
the bag so that the bag presses the adhesive against the inner side wall 
of the squeezebottle during heat-activation of the adhesive. This 
condition may also be accomplished by evacuating the space between the bag 
and the squeezebottle before pressing the bag fitment fully into the 
bottle finish. For example, squeezebottle 10 is first placed in a vacuum 
chamber, not shown. Slot 36 in rigid fitment 20 permits evacuation of air 
from between bag 24 and the squeezebottle. Then rigid fitment 20 is 
pressed into finish 14 to seal squeezebottle 10 in a substantially 
air-tight manner. When squeezebottle 10 is removed from the vacuum 
chamber, the vacuum remains between bag 24 and the inner side wall of 
squeezebottle 10. Atmospheric pressure inside bag 24 presses bag 24 
against the inner side wall. Adhesive heat activation may then proceed 
from either inside bag 24 or outside squeezebottle 10. 
Another alternative includes providing adhesive stripes parallel to the 
axis of the container along the full length of bag 24. In this situation, 
the fluid-filled bag cannot invert when the squeezebottle is squeezed. 
However, if the adhesive stripes are sufficiently spaced apart, the bag 
may collapse radially, generating axial folds. Because adhesive holds the 
bag to the side wall of the outer container along the full length of the 
bag, bag collapse may not require a diptube to prevent premature collapse 
near the discharge opening. 
While particular embodiments of the present invention have been illustrated 
and described, it will be obvious to those skilled in the art that various 
changes and modifications may be made without departing from the spirit 
and scope of the invention, and it is intended to cover in the appended 
claims all such modifications that are within the scope of the invention.