U.S. patent application number 15/166337 was filed with the patent office on 2017-11-30 for plastic bottle and base cup for a pressurized dispensing system.
This patent application is currently assigned to S.C. Johnson & Son, Inc.. The applicant listed for this patent is S.C. Johnson & Son, Inc.. Invention is credited to David R. Carlson, Daniel S. McGrath, Niles Stenmark, Christopher P. Wolak.
Application Number | 20170341849 15/166337 |
Document ID | / |
Family ID | 58794215 |
Filed Date | 2017-11-30 |
United States Patent
Application |
20170341849 |
Kind Code |
A1 |
Wolak; Christopher P. ; et
al. |
November 30, 2017 |
PLASTIC BOTTLE AND BASE CUP FOR A PRESSURIZED DISPENSING SYSTEM
Abstract
A container for a pressurized dispensing system. The container
includes a plastic bottle and a base cup bonded to a rounded bottom
of the plastic bottle with a hot melt adhesive. The base cup has a
bottom surface that allows the container to stand upright. A method
of forming the container is also provided wherein hot melt adhesive
is deposited in a recessed region in a top wall of a pedestal of
the base cup, and a center region of the rounded bottom of the
plastic bottle is pressed against the hot melt adhesive such that
the adhesive spreads out over the recessed region and the rest of
the top wall of the pedestal. After the hot melt adhesive cools,
the bottle is securely bonded to the base cup.
Inventors: |
Wolak; Christopher P.;
(Racine, WI) ; Carlson; David R.; (Cedarburg,
WI) ; McGrath; Daniel S.; (Gurnee, IL) ;
Stenmark; Niles; (Franklin, WI) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
S.C. Johnson & Son, Inc. |
Racine |
WI |
US |
|
|
Assignee: |
S.C. Johnson & Son,
Inc.
Racine
WI
|
Family ID: |
58794215 |
Appl. No.: |
15/166337 |
Filed: |
May 27, 2016 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
B65D 2207/00 20130101;
B65D 83/28 20130101; B65D 23/001 20130101; B65D 1/023 20130101;
B65D 1/0261 20130101; B65D 83/38 20130101 |
International
Class: |
B65D 83/38 20060101
B65D083/38; B65D 1/02 20060101 B65D001/02; B65D 83/28 20060101
B65D083/28 |
Claims
1. A container for a pressurized dispensing system, the container
comprising: a bottle including an opening at a top end and a
rounded bottom at a bottom end, the bottle being molded from a
plastic material; and a base cup positioned adjacent to the rounded
bottom of the bottle, the base cup including (i) a bottom surface
that allows the container to stand upright and (ii) a pedestal
provided around a center area of the rounded bottom of the bottle,
the pedestal including a top wall having a first surface and a
continuously curved second surface adjacent to the first surface,
wherein a hot melt adhesive provided on the the first surface
attaches the base cup to the bottle, wherein the center area of the
rounded bottom of the bottle is spaced from the second surface of
the base cup, and wherein a center axis of the bottle passes
through the second surface of the base cup.
2. The container according to claim 1, wherein the adhesive is
spread over the second surface of the base cup and the rest of the
top wall of the pedestal of the base cup.
3. A container for a pressurized dispensing system, the container
comprising: a bottle including an opening at a top end and a
rounded bottom at a bottom end, the bottle being molded from a
plastic material; and a base cup positioned adjacent to the rounded
bottom of the bottle, the base cup including a bottom surface that
allows the container to stand upright and a pedestal provided
around a center area of the rounded bottom of the bottle, the
pedestal including a top wall, with a recessed area being formed in
the top wall, wherein a hot melt adhesive provided on the top wall
attaches the base cup to the bottle, with the hot melt adhesive
including an acrylic component, wherein the center area of the
rounded bottom of the bottle is spaced from the recessed area of
the base cup.
4. The container according to claim 3, wherein the hot melt
adhesive includes ethylene-vinyl acetate and the acrylic
component.
5. The container according to claim 1, wherein the bottle is formed
from polyethylene terephthalate.
6. The container according to claim 1, wherein the base cup is
formed from a resin selected from the group consisting of
polyethylene terephthalate, polypropylene, and polyester.
7. The container according to claim 1, wherein a plurality of
apertures is provided in the bottom surface of the base cup.
8. A method of forming a pressurized dispensing system, the method
comprising: heating a hot melt adhesive such that the hot melt
adhesive is in a molten state; applying a plurality of deposits of
the molten hot melt adhesive to a pedestal of a base cup;
positioning a rounded bottom of a plastic bottle adjacent to the
base cup such that the rounded bottom of the bottle contacts the
molten hot melt adhesive and a center area of the rounded bottom of
the bottle is spaced from an adjacent continuously curved surface
of the pedestal, with a center axis of the bottle passing through
the continuously curved surface; and cooling the molten hot melt
adhesive to thereby attach the base cup to the plastic bottle in an
area of a top wall of the pedestal that is adjacent to the
continuously curved surface of the pedestal.
9. The method according to claim 8, wherein the molten hot melt
adhesive forms a layer between the rounded bottom of the bottle and
the pedestal of the base cup such that the rounded bottom of the
bottle does not contact the pedestal.
10. The method according to claim 8, wherein the hot melt adhesive
has a viscosity of 2,500 cps to 5,000 cps when it is applied to the
pedestal of the base cup.
11. The method according to claim 8, wherein the hot melt adhesive
is heated to a temperature of about 225.degree. F. to about
400.degree. F. when it is applied to the pedestal of the base
cup.
12. The method according to claim 8, wherein the hot melt adhesive
includes an acrylic component.
13. The method according to claim 12, wherein the hot melt adhesive
includes ethylene-vinyl acetate and the acrylic component.
14. An aerosol dispensing system comprising: a bottle including an
opening at a top end and a rounded bottom at a bottom end, the
bottle being molded from a plastic material, and the bottle
containing an aerosol product under pressure; a spray mechanism
attached to the top end of the bottle, the spray mechanism
including a nozzle through which the aerosol product can be
discharged; and a base cup positioned adjacent to the rounded
bottom of the bottle, the base cup including (i) a bottom surface
that allows the container to stand upright and (ii) a pedestal
provided around a center area of the rounded bottom of the bottle,
the pedestal including a top wall having a first surface and a
continuously curved second surface adjacent to the first surface,
wherein a hot melt adhesive provided on the the first surface
attaches the base cup to the bottle, wherein the center area of the
rounded bottom of the bottle is spaced from the second surface of
the base cup, and wherein a center axis of the bottle passes
through the second surface of the base cup.
15. The system according to claim 14, wherein the adhesive is
spread on the second surface of the base cup and the rest of the
top wall of the pedestal of the base cup.
16. The system according to claim 14, wherein the hot melt adhesive
includes an acrylic component.
17. The system according to claim 16, wherein the hot melt adhesive
includes ethylene-vinyl acetate and the acrylic component.
18. The system according to claim 14, wherein the bottle is formed
from polyethylene terephthalate.
19. The system according to claim 14, wherein the base cup is
formed from a resin selected from the group consisting of
polyethylene terephthalate, polypropylene, and polyester.
20. The system according to claim 14, wherein a plurality of
apertures is provided in the bottom surface of the base cup.
Description
BACKGROUND
Field of the Invention
[0001] Our invention generally relates to a pressurized dispensing
system, such as a system that dispenses an aerosol product. More
specifically, our invention relates to a dispensing system that
includes a plastic bottle containing a product under pressure, with
a base cup being attached to the plastic bottle to allow the system
to stand upright.
Related Art
[0002] Pressurized dispensing systems, such as systems used to
dispense aerosol products, have conventionally included metallic
(e.g. steel or aluminum) containers for containing the product
under pressure before it is dispensed from the system. Examples of
products that are dispensed with such systems include air
fresheners, fabric fresheners, insect repellants, paints, body
sprays, hair sprays, shoe or footwear spray products, whipped
cream, and processed cheese. Recently, there has been increased
interest in using plastic bottles as an alternative to metallic
containers in pressurized dispensing systems because plastic
bottles have several potential advantages. For example, plastic
bottles may be easier and cheaper to manufacture than metallic
containers, and plastic bottles can be made in a wider variety of
interesting shapes than metallic containers.
[0003] One of the biggest challenges in manufacturing plastic
bottles for pressurized dispensing systems is providing the plastic
bottle with enough structural integrity be able to withstand the
internal pressure required for full evacuation of the product. For
example, an internal pressure required for compressed gas aerosols
generally ranges from 45 PSIG to 200 PSIG at 70.degree. F. whereas
liquefied gas aerosols generally ranges from 17 PSIG to 108 PSIG at
70.degree. F. If the plastic aerosol bottle is not provided with
enough structural integrity to withstand such pressurization
through the life of the dispensing system, then there is a risk
that the plastic aerosol bottle could rupture. In this regard, it
is known that the pressure inside a plastic bottle can weaken the
plastic structure over time, for example, by creating stress crazes
and cracks in the plastic. Moreover, a pressurized dispensing
system might be subject to an event that tests the structural
integrity of its plastic bottle, for example, when the bottle is
dropped, or when the bottle is left in a high temperature
environment that heats the contents of the bottle to thereby
increase the already high internal pressure. And the potential of a
pressurized plastic bottle rupturing as a result of any of these
events presents a clear safety risk to users of the dispensing
system.
[0004] From a user functionality standpoint, the ability of a
dispensing system to stand upright is very important. But, the use
of a plastic bottle in a pressurized dispensing system presents a
challenge with respect to making the system be able to stand
upright. While the base of the plastic bottle could be molded in a
flat shape that allows the bottle to stand upright, it has been
found that imparting such a flat shape often creates problems. For
example, contours that result from forming a vertically stable base
in the bottle may be highly susceptible to stress crazing and
cracking. Further, a contoured base may be prone to bursting if the
plastic bottle is dropped, and the base may deform if the pressure
inside the plastic bottle increases, e.g., in elevated temperature
environments.
[0005] It has been found that a rounded base in a plastic bottle of
a pressurized dispensing system is far less susceptible to stress
crazing and cracking then contoured bases. Further, as compared to
a contoured base, a rounded plastic base in a plastic bottle is
less prone to bursting when dropped and less easily deformed in
elevated temperatures when the bottle is filled with a product and
pressurized. But, on the other hand, a rounded base does not
provide a surface for making the plastic bottle stand upright.
Thus, a secondary piece, or "base cup," can be attached to the
rounded bottom of a plastic bottle, with the base cup providing a
flat surface that allows the plastic bottle to stand upright.
[0006] While a base cup is conceptually an easy solution for making
a plastic bottle with a rounded bottom stand upright, in practice
attaching a base cup to a plastic bottle as part of a pressurized
dispensing system is a tremendous challenge. The pressurized
dispensing system will likely be exposed to handling and different
environments before ever reaching the end consumer. And, during
handling or in different environments, the pressurized dispensing
system may encounter conditions that may weaken the attachment
between the base cup and bottle, such as varying temperatures and
impacts. If the attachment is weakened, the base cup might later
become detached from the bottle when being used by the end
consumer. It is critical that this does not happen--separation of
the base cup and bottle will at least result in unsatisfied
consumers, if not result in significant safety hazards for the
consumers.
[0007] While there are several techniques that could conceivably be
used to securely attach a base cup to a plastic bottle, there are
problems with most of these techniques, particularly in the context
of pressurized dispensing systems. For example, while welding
techniques such as sonic, vibration, laser, and spin welding might
be used to tightly attach a base cup to the bottle, the heat
generated during the welding softens the material to a molten
state, which in turn could lead to problematic stress risers when
the bottle is subsequently filled with a product and pressurized.
Additionally, welding plastics requires similar plastic families to
be used for both the base and base cup, which limits the resins
that can be used. Another way that a base cup might be attached to
the bottom of a plastic bottle is through some method of mechanical
attachment, for example, the bottom of the bottle could be molded
in a shape that locks to the base cup. However, such shaping of the
bottom of the bottle may lead to the same types of problems that
are found when the bottom of the bottle is made flat to make the
bottle stand upright on its own.
[0008] As an alternative to welding and mechanical attachments,
adhesives might be used to attach the base cup to the plastic
bottles. And while there are many types of adhesives that might be
considered, many of these adhesives are not suited for use in
conjunction with a plastic bottle in a pressurized dispensing
system. For example, UV cured glues shrink when cured, which would
put additional stress points on the plastic bottle, thereby leading
to stress crazing or stress cracking. As another example, solvent
based structural adhesives, such as some epoxies, may not be
suitable because these adhesives are generally difficult to cure
and have poor impact resistance.
SUMMARY OF THE INVENTION
[0009] According to one aspect, our invention provides a container
for a pressurized dispensing system. The container comprises a
bottle including an opening at a top end and a rounded bottom at a
bottom end, with the bottle being molded from a plastic material.
The container also includes a base cup adhered to the rounded
bottom of the bottle with a hot melt adhesive, with the base cup
including a pedestal adjacent to a center of the rounded bottom of
the bottle, and with the base cup having a flat bottom surface that
allows the container to stand upright. The hot melt adhesive forms
a layer between the pedestal and the rounded bottom of the bottle,
with the hot melt adhesive being spread over the pedestal to
thereby form an adhesive layer that prevents contact between the
rounded bottom of the bottle and the pedestal.
[0010] According to another aspect, our invention provides a method
of forming a pressurized dispensing system. The method includes
heating a hot melt adhesive such that the hot melt adhesive is in a
molten state, and depositing the molten melt adhesive in a recessed
region in a top wall of a pedestal in a base cup. The method also
includes pressing a center region of a rounded bottom of a plastic
bottle against the molten hot melt adhesive such that the molten
hot melt adhesive spreads out over the recessed region and the rest
of the top wall of the pedestal, and cooling the molten hot melt
adhesive to to thereby attach the base cup to the plastic
bottle.
[0011] According to yet another aspect, our invention provides an
aerosol dispensing system. The system includes a bottle having an
opening at a top end and a rounded bottom at a bottom end, with the
bottle being formed from a plastic material, and with the bottle
containing an aerosol product under pressure. A spray mechanism is
attached to the top end of the bottle, with the spray mechanism
including a nozzle through which the aerosol product can be
discharged. A base cup is adhered to the rounded bottom of the
bottle with a hot melt adhesive, with the base cup including a
pedestal adjacent to a center of the rounded bottom of the bottle,
and the base cup having a flat bottom surface that allows the
aerosol dispensing system to stand upright. The hot melt adhesive
forms a layer between the pedestal and the rounded bottom of the
bottle, with the hot melt adhesive being spread over the pedestal
to prevent the rounded bottom of the bottle from contacting the
pedestal.
BRIEF DESCRIPTION OF THE DRAWINGS
[0012] FIG. 1 is a side view of a plastic bottle for use in a
pressurized dispensing system according to an embodiment of our
invention.
[0013] FIG. 2 is an elevation view of the upper side of a base cup
according to an embodiment of our invention.
[0014] FIG. 3 is a top view of the base cup shown in FIG. 2.
[0015] FIG. 4 is a cross-sectional view of a base cup shown in FIG.
2 as taken along line 4-4.
[0016] FIG. 5 is a bottom view of the base cup shown in FIG. 2.
[0017] FIG. 6 is an elevation view of the lower side base cup shown
in FIG. 2.
[0018] FIG. 7 is a cross-sectional view of the base cup shown in
FIG. 2 as taken along line 4-4, with an adhesive applied to the
base cup.
[0019] FIG. 8 is a cross-sectional view of a base cup shown in FIG.
2 as taken along line 4-4, with the base cup being adhered to the
bottom of a plastic bottle according to an embodiment of our
invention.
[0020] FIG. 9 is a side view of a pressurized dispensing system
according to an embodiment of our invention.
[0021] FIG. 10 is a cross-sectional view of the pressurized
dispensing system shown in FIG. 9 as taken along line 10-10.
DETAILED DESCRIPTION OF THE INVENTION
[0022] Our invention generally relates to pressurized dispensing
systems. More specifically, our invention relates to a dispensing
system that includes a plastic bottle containing a product under
pressure, with a base cup being attached to the plastic bottle to
allow the system to stand upright.
[0023] In the descriptions that follow, we will sometimes explain
features of our invention in the specific context of an aerosol
dispensing system. Those skilled in the art will readily
appreciate, however, that our invention is not limited to use with
aerosol products. Rather, the pressurized dispensing systems
described herein could alternatively be used in conjunction with
products other than aerosols. For example, the dispensing systems
described herein might be used to dispense foam products such as
shaving cream or soap, or used to dispense food products such as
soda, whipped cream, or processed cheese.
[0024] FIG. 1 is a side view of a plastic bottle 100 for use in a
pressurized dispensing system according to an embodiment of our
invention. The bottle 100 includes an upper end 102, a lower end
106, and a body section 104. At the upper end 102 is a neck region
108 having a crimping ring 110 surrounding an opening 112 of the
bottle 100. The body section 104 extends downward from the neck
region 108 to the lower end 106 of the bottle 100. At the lower end
106, the bottle 100 is provided with a rounded bottom 114. It
should be noted that the shape, size, and proportions of the bottle
100 shown in FIG. 1 are merely exemplary. Indeed, one of the
advantages of using plastic to form the bottle 100 is that the
plastic may be molded into a wide variety of shapes and sizes. In
this regard, the bottle 100 may be formed using injection and/or
blow molding techniques, which are well known in the art. In such
techniques a plastic preform is first formed using injection
molding; the plastic preform is subsequently heated and stretch
blow molded into the final shape of the bottle 100.
[0025] A spray mechanism (not shown) including a valve structure
may be provided to the upper end 102 of the bottle 100, with the
spray mechanism being crimped onto the crimping ring 108. Such a
spray mechanism includes a nozzle through which product from the
bottle is dispensed, for example, as an aerosol mist. These types
of spray mechanisms are well known in the art. And along these
lines, it will be appreciated by those skilled in the art that the
upper end 102 of the bottle 100 may have a different configuration
than as shown in order to accommodate other types of spray
mechanisms. For example, the bottle might be configured without the
crimping ring 100, with the spray mechanism being crimped to the
inside of the neck region 108 of the bottle 100 at a position
adjacent to the opening 112.
[0026] The lower end 106 of the bottle 100 includes a rounded
bottom 114. As used herein, the term "rounded" means that the
bottom 114 is curved over the area at the lower end 106 of the
bottle 100. That is, a "rounded" bottom includes shapes that could
be described as spherical, elliptical, domed, etc. As generally
discussed above, the rounded bottom 114 is advantageous compared to
other shapes because the rounded bottom 114 is less susceptible to
problematic stress crazing and cracking when the bottle is filled
with a product and pressurized. For example, the rounded bottom 114
does not include contours that would be required to form a
self-standing bottle. The round shape of the bottom 114 provides
other advantages as well. For example, as the plastic is formed
into the rounded shape during a blow molding process, stretch
crystallinity is formed in the polymers making up the plastic.
[0027] Further, the gate in an injection mold used to form a
preform of the bottle may be provided at a position corresponding
to the center of the rounded bottom 114, which leads to the center
being the thickest section of the rounded bottom 114. By being the
thickest section, the center will expand the least when the bottle
is pressurized with a product, making the center of the rounded
bottom 114 a good location for applying an adhesive to connect a
base cup, as will be described in detail below.
[0028] The bottle 100 may be formed from a wide variety of
plastics. Some examples of such plastics include branched or linear
polyethylene terephthalate (PET), polycarbonate (PC), polyethylene
naphthalate (PEN), polyethylene furanoate (PEF), polyolefins (PO)
such as polyethylene (PE) and polypropylene (PP), and other
polyesters, and blends thereof.
[0029] FIGS. 2-6 are views of a base cup 200 according to an
embodiment of our invention. The base cup 200 is configured to be
attached to the rounded bottom 114 of the bottle 100, as will
describe in detail below. The base cup 200 includes a side wall 202
defining an outer perimeter of the base cup 200. At the bottom of
the base cup 200, a bottom wall 204 extends inward from the
cylindrical wall 202, with a plurality of apertures 206 being
formed in the bottom wall 204. A pedestal 208 projects upwardly
from the bottom wall 204 and within the space enclosed by the
cylindrical side wall 202. More specifically, the pedestal 208 is
formed with a cylindrical wall 210 that extends from the bottom
wall 204 to a top wall 212. A recessed area 214 is formed in the
top wall 212.
[0030] The base cup 200 may be an injection molded resin,
thermoformed, or stretch blow molded. Examples of polymeric resins
that could be used to form the base cup 200 include PET, PEN, PEF,
polypropylenes, polyethylenes, polyesters, polycarbonates, nylons,
poly(vinyl chloride) and polystyrenes. Some specific examples of
commercially available resins that could be used to form the base
cup 200 include FHR Polypropylene P5M6K-048 (a polypropylene
copolymer) by Flint Hills Resources of Wichita, Kans.,
PETROTHENE.RTM. NA206000 (a low density polyethylene) by
LyondellBasell Industries of Northbrook, Ill., and DURASTAR'
DS1910HF (a copolyester) by Eastman Chemical Company of Kingsport,
Tenn. Ultimately, those skilled in the art will recognize that the
selection of the material for forming the base cup 200 will depend
on several factors, including cost and appearance (e.g., a colored
resin versus a clear resin). The selection of the material for
forming the base cup 200 may also depend on characteristics of the
surfaces of the base cup, as will be discussed in detail below.
[0031] FIGS. 7 and 8 show the application of an adhesive 300 to the
pedestal 208 of the base cup 200 and the subsequent attachment of
the bottle 100 to the base cup 200. This process starts with an
adhesive 300 being deposited in the recessed area 214 of the
pedestal 208. The adhesive 300 may be applied with a single deposit
or multiple deposits in the recessed area 214. As will be discussed
below, the adhesive 300 is a hot melt, meaning that it is heated to
a liquid state and applied to the base cup 200 in that liquid
state. The rounded bottom 114 of the bottle 100 is subsequently
brought into contact with the adhesive 300, which causes the
adhesive 300 to spread out over the recessed area 214 and the top
wall 212 of the pedestal 208. The adhesive 300 is then allowed to
cool, with the bottle 100 thereby becoming firmly attached to the
base cup 200 by the adhesive 300. The apertures 206 in the bottom
wall 204 of the base cup 200 increase the speed which the adhesive
300 cools by allowing air to flow to the inside of the base cup 100
where the bottle 200 is attached.
[0032] In the attachment process the adhesive 300 is applied to the
base cup 200 first, as opposed to being applied to the bottle 100.
The adhesive 300 may therefore cool slightly before it contacts the
bottle 100. This is important because a temperature spike on points
of the plastic of the bottle 100 where the adhesive 300 would be
applied could potentially soften the plastic and thereby weaken the
bottle 100. That is, if the adhesive 300 was applied first the
bottle 100, the area of the bottle 100 that contacts the adhesive
might be susceptible to stress crazing and stress cracking when the
bottle 100 is filled with a pressurized product. The slight cooling
of the adhesive 300 while the adhesive is first applied to the base
200 reduces the risk of the adhesive 300 damaging the bottle
100.
[0033] By configuring the pedestal 208 with a recessed area 212,
the base cup 200 can accommodate a small range of the sizes of the
bottle 100, e.g., variances arising from manufacturing tolerances
in molding the bottle 100. Further, the recessed area 212 is formed
around the center of the rounded bottom 114 of the bottle 100. As
discussed above, the bottle 100 may be formed in a process where a
preform is injection molded, with injection gate corresponding to
the center of the rounded bottom 114 in the bottle 100 ultimately
formed in the process. Such a configuration results in a slight
bulge being formed at the center of the rounded bottom 114. The
recessed area 212 of the pedestal 208 can accommodate such a bulge
at the center of the rounded bottom 114.
[0034] As shown in FIG. 8, the adhesive 300 spreads out evenly over
recessed area 214 and the top wall 212 of the pedestal 208 such
that there is a layer of adhesive 300 between the pedestal 208 and
the rounded bottom 114 of the bottle 100. That is, the adhesive 300
make it such that there is little, if any, contact between the
pedestal 208 of the base cup 200 and the rounded bottom 114 of the
bottle 100. That the layer of adhesive 300 separates the pedestal
308 and the rounded bottom 114 is highly advantageous because
contact points between the pedestal 208 and rounded bottom 114 are
in effect weak spots that increase the risk of the base cup 200
separating from the bottle 100, for example, during an impact; a
strong bond is formed between the base cup 200 and the bottle 100
when the adhesive 300 is spread out over the entirety of the area
between the pedestal 208 and the rounded bottom 114. Factors that
can be adjusted to ensure that the adhesive 300 spreads out over
the pedestal 208 will be discussed in detail below.
[0035] There are a wide variety of adhesives that could potentially
be used to attach the base cup 200 to the bottle 100. But, as
discussed above, some types of adhesives (such as UV cured glues
and solvent based structural adhesives) have properties that are
not suited for use in a pressurized dispensing system. Hot melt
adhesives, however, do have several properties that facilitate the
attachment of a base cup to a plastic bottle in a pressurized
dispensing system. In particular, we have found that hot melt
adhesives with a low surface energy work well to attach the base
cup 200 to the bottle 100 in the process describe above. Such hot
melt adhesives have elastic-like properties that impart impact
resistance to the system. Further, such hot melt adhesives are
flexible such that the base cup 200 can remain firmly attached to
the bottle 100 even as the bottle 100 expands and contracts. Still
further, a hot melt adhesive provides minimal stress when the
adhesive is applied to the base cup 200 and bottle 100. That is,
because these adhesives can be applied at a lower temperature, the
adhesives are less likely to overheat the base cup 200 and bottle
100, and as such, the base cup 200 and/or bottle 100 can be made
thinner without risking that they will melt during the attachment
process. And the low melting temperature of the adhesive 300 means
that the adhesive will more quickly cool to the final, adhered
state. Hot melt adhesives also induce less stress on the bottle 100
than other types of adhesives from the standpoint that shrinkage of
hot melt adhesives is negligible as the adhesives are cooled. A
further property of hot melt adhesives that is beneficial is the
green strength of such adhesives, green strength being the ability
of an adhesive to hold before it is cured. Still further, hot melt
adhesives can quickly set, with a 75 to 100 percent adhesive
strength being achieved after only a few seconds of drying.
[0036] One of the significant properties of the hot melt adhesive
300 is its viscosity at the time it is applied to the base cup 200.
As discussed above, the adhesive 300 spreads out over the recessed
area 214 and the top wall 212 of the pedestal 208. If the viscosity
of the adhesive 300 is too high, the adhesive 300 may not spread
out over the area as intended. On the other hand, if the viscosity
of the adhesive 300 is too low, the adhesive 300 may spread out too
much and spill out over the edge of the top wall 212. In either
case of the viscosity of the adhesive 300 being too high or too
low, the result is insufficient adhesive 300 coverage of the
surface area between the pedestal 208 and the rounded bottom 114 of
the bottle 100. This means that there will be less adhesion between
the base cup 200 and the bottle 100--the base cup 200 may in turn
easily separate from the bottle 100 when it is pulled, pealed, or
when it is dropped. Through experiments we found that a hot melt
having a viscosity of 2500 to 5000 cps at application temperature
can effectively spread out over the pedestal 208 as described
herein. With a viscosity in this range, the hot melt adhesive 300
spreads evenly around the recessed area 214 and the top wall 212,
and an even bead of adhesive 300 is formed around the edge of the
top wall 212 adjacent to the cylindrical wall 210.
[0037] The surface energy of the pedestal 208 is another factor
that affects how the adhesive 300 will spread out on the pedestal
208. The material from which the surfaces of the pedestal 208 are
constructed will have some inherent surface energy that may, or may
not, facilitate the spreading of the adhesive 300--the adhesive 300
will more easily spread out on a surface that has a higher surface
energy than a surface that has a lower surface energy. When the
surfaces of the base cup 200 do not have a desired surface energy,
the surfaces may be modified to increase spreading of the adhesive
300. For example, roughening the top wall 212 and the recessed area
214 creates crevices that allow the adhesive 300 to bite into and
thereby more easily spread out over the surfaces. As will be
appreciated by those skilled in the art, the surfaces of the top
wall 212 and the recessed area 214 can be made rougher in a process
of molding the base cup 200, or the surfaces could be made rougher
after molding the base cup 200. Another example of a treatment that
could be applied to the surfaces of the top wall 212 and the
recessed area 214 to increase spreading of the adhesive is corona
treating.
[0038] In such a process, a high voltage discharge is directed to
the surfaces that are to be modified (i.e., the surfaces of the top
wall 212 and the recessed area 214). The result is that an
increased chemical connection can be formed between the corona
treated surfaces and the adhesive 300. We found that corona
treatment significantly increased spreading of the adhesive 300
when the base cup 200 is formed from low density polyethylene.
[0039] Any modification of the properties of the surfaces of the
pedestal 208 may be selected in combination with the viscosity of
the adhesive 300. That is, the surfaces of the pedestal 208 may be
modified to achieve a desired spreading of the adhesive 300 in a
case where the adhesive 300 is set to have a particular viscosity
at the time of its application. Alternatively, the viscosity of the
adhesive 300 at the time of application can be increased or
decreased to achieve a desired spreading given particular
properties of the surface of the pedestal 208. In a specific
example, we found that when an adhesive having a viscosity of 2500
to 5000 cps was used, a corresponding VDI 45 finish on the surfaces
of the recessed area 214 and top wall 212 resulted in the adhesive
300 being evenly spread over the surfaces so that a strong bond was
formed between the base cup 200 and the bottle 100.
[0040] As to particular hot melt adhesives that can be used in our
invention, we have found that solid based hot melt adhesives
provide the best combination of properties for attaching the base
cup 200 to the plastic bottle 100. Such adhesives are heated to the
molten viscosity, with the higher the heating temperature the lower
resulting viscosity of the adhesives. These adhesives are applied
in the molten state, and when the adhesives are cooled to form a
bond. Notably, there is minimal shrinkage of these types of
adhesives as they are cooled--the density of applied adhesive is
approximately the density of adhesive after cooling.
[0041] We specifically found that hot melt adhesives that are based
on ethylene-vinyl acetate (EVA) or polyamides provide good bonding
between the base cup 200 and the plastic bottle 100. Examples of
such adhesives are sold under the tradenames HM-302D by Ellsworth
Adhesives of Germantown, Wis., and SCOTCH-WELD.TM.3792 LM and 3789Q
by 3M of Maplewood, Minn. We particularly found that adhesives that
include an acrylic component provide the best bonding between the
base cup 100 and plastic bottle in embodiments of our invention. An
example of such an adhesive is comprised of EVA, an acrylic (which
we believe to be poly(butly acrylate) or poly(ethyl acrylate)), and
polystyrene and is sold under the tradename HMS-792 by Ellsworth
Adhesives. Without being bound by theory, we think that the
combination of a hot melt component (e.g., EVA) and an acrylic
(e.g., poly(butly acrylate) or poly(ethyl acrylate)) provides
bondings at the molecular level between the base cup 200 and the
bottle 100, with the hot melt component providing a carrier for the
acrylic that provides a van der Walls type bond.
[0042] The hot melt adhesives described herein are easy to work
with. These adhesives are molten with a viscosity in the range of
2500 to 5000 cps at temperatures around 225-400.degree. F. Further,
these hot melt adhesives have significant open times, i.e., the
maximum amount of time after the adhesive is applied that a bond
can be formed with additional pressure being applied. In this
regard, we found that an acrylic hot melt adhesive had open time
around 75 seconds, while other hot melt adhesives had open times of
about 40 to about 50 seconds. With such extended open times, the
hot melt adhesives can be applied to multiple base cups in a
production line before bottles are brought into contact with the
adhesives, thereby providing flexibility in the manufacturing
process.
[0043] In alternative embodiments of our invention, other types of
adhesives may be used to attach the base cup 200 to the bottle 100.
For example, a pressure sensitive adhesive might be used, such as
EVA blended with a styrene block copolymer. An adhesive of this
type is sold as H7911-334B by Bostik of Paris, France. Another
styrenic copolymer based adhesive that could be used is H20182 by
Bostik. Those skilled in the art will recognize still other
adhesives that would form a bond between the base cup 200 and the
bottle 100 as described herein.
[0044] TABLE 1 shows tests that we conducted to determine the
adhesive strength between a base cup bonded to a plastic bottle in
terms of the pull off force required to separate the base cup and
the bottle. In these tests the plastic bottle was molded from PET,
and the base cup was molded from the materials as indicated. The
base cup and bottle had the configurations described above. The
bottle and the base cup were sized such that there was about 1.72
in.sup.2 of adhesive area between the pedestal of the base cup and
the rounded bottom of the bottle. Note, the UV cured adhesive
DEVCON.RTM. TRU-BOND.TM. PB 3500 by ITW Performance Polymers of
Danvers, Mass., was tested for comparison to the hot melt
adhesives.
TABLE-US-00001 TABLE 1 Amount of Pull Adhesive Force Adhesive (g)
Base Cup Material (lbf) EVA + Acrylic + 0.95 Polypropylene
Copolymer 85.90 Polystyrene (Flint Hills P5M6K-048) (Ellsworth HMS
792) EVA + Acrylic + 0.95 Low Density 96.10 Polystyrene
Polyethylene (Ellsworth HMS 792) (PETROTHENE .RTM. NA206000) EVA +
Acrylic + 0.95 Copolyester 152.00 Polystyrene (DURASTAR .TM.
(Ellsworth HMS 792) DS1910HF) EVA + Acrylic + 1.00 Polypropylene
Copolymer 107.00 Polystyrene (Flint Hills P5M6K-048) (Ellsworth HMS
792) Over-Heated EVA + Acrylic + 1.00 Low Density 97.60 Polystyrene
Polyethylene (Ellsworth HMS 792) (PETROTHENE .RTM. Over-Heated
NA206000) EVA + Acrylic + 1.00 Copolyester 175.00 Polystyrene
(DURASTAR .TM. (Ellsworth HMS 792) DS1910HF) Over-Heated EVA +
Polystyrene 0.90 Polypropylene Copolymer 68.80 (SCOTCH-WELD .TM.
(Flint Hills P5M6K-048) 3792) EVA + Polystyrene 0.90 Low Density
28.30 (SCOTCH-WELD .TM. Polyethylene 3792) (PETROTHENE .RTM.
NA206000) EVA + Polystyrene 0.90 Copolyester 95.00 (SCOTCH-WELD
.TM. (DURASTAR .TM. 3792) DS1910HF) Polyamide 0.90 Polypropylene
Copolymer 55.50 (SCOTCH-WELD .TM. (Flint Hills P5M6K-048) 3789Q)
Polyamide 0.90 Low Density 41.20 (SCOTCH-WELD .TM. Polyethylene
3789Q) (PETROTHENE .RTM. NA206000) Polyamide 0.90 Copolyester 93.70
(SCOTCH-WELD .TM. (DURASTAR .TM. 3789Q) DS1910HF) EVA 0.90
Polypropylene Copolymer 38.90 (Ellsworth HM-302-D) (Flint Hills
P5M6K-048) EVA 0.90 Low Density 3.80 (Ellsworth HM-302-D)
Polyethylene (PETROTHENE .RTM. NA206000) EVA 0.90 Copolyester 56.60
(Ellsworth HM-302-D) (DURASTAR .TM. DS1910HF) UV Cured Adhesive
0.30 Polypropylene copolymer 15.50 (TRU-BOND .TM. PB (Flint Hills
P5M6K-048) 3500) UV Cured Adhesive 0.30 Low Density 9.70 (TRU-BOND
.TM. PB Polyethylene 3500) (PETROTHENE .RTM. NA206000) UV Cured
Adhesive 0.30 Copolyester 45.20 (TRU-BOND .TM. PB (DURASTAR .TM.
3500) DS1910HF)
[0045] As can be seen from the data in TABLE 1, the hot melt
adhesive containing EVA and an acrylic provided the strongest bond
between the base cup and the bottle. It should also be noted that
all of the hot melt adhesives provided at least comparable bonding
to the UV cured adhesive. But, as discussed above, the hot melt
adhesives are advantageous over UV cured adhesives in other ways.
For example, hot melt adhesives do not shrink upon hardening,
whereas UV cured adhesives do significantly shrink, which can harm
the plastic structure of the bottle.
[0046] As generally discussed above, due to potential safety
hazards, a pressurized dispensing system must be able to withstand
impacts without failing. In this regard, U.S. Department of
Transportation (DOT) regulations specifically require that a
pressurized dispensing container must be able to withstand being
dropped from a height of 1.8 m both onto the bottom of the
container and when the container is angled at 45.degree. relative
to the ground. We applied DOT tests to the bottle and base cup
combinations shown in TABLE 1. We found that the base cup and
bottle bonded together with the hot melt adhesives did not
generally become separated from the impact of the drop. We believe
that the hot melt adhesives provide a flexible layer between the
base cup and bottle that does not fatigue as a result of the
impact, and this flexing likely contributed to the base cup
remaining attached to the bottle in the drop tests.
[0047] The combination of the bottle 100 and the base cup 200 can
form a container for a pressurized dispensing system, such as a
system for dispensing an aerosol product. An example of this type
of pressurized dispensing system 400 is shown in FIGS. 9 and 10. In
the system 400, the rounded bottom 114 of the bottle 100 is adhered
with a hot melt adhesive 300 to the pedestal 208 of the base cup
200. The base cup 200 allows the system 400 to stand upright on a
flat surface despite the bottle 100 having a rounded bottom 114. As
discussed above, the adhesive 300 creates a layer between the
rounded bottom 114 and the pedestal 208. As such, the outer rim 216
is the only portion of the base cup 200 that contacts the bottle
100. Notably, in this embodiment the outer rim 216 is positioned
adjacent to the body section 104 of the bottle 100 such that the
rounded bottom 114 cannot be seen. In other embodiments, however,
the outer rim 216 is positioned lower on the bottle 100 such that a
portion of the rounded bottom 114 can be seen. At the top of the
system 400 of the bottle is a spray mechanism 402, as discussed
above. The pressurized product contained within the bottle 100 is
dispensed through the spray mechanism 402 in this case as an
aerosol mist. Although not shown, a cap may be provided over the
spray mechanism 402. In sum, the bottle 100 and base cup 200
provide for a convenient and attractive.
[0048] In a specific embodiment of our invention, the system 400 is
used to dispense an air freshening composition. Examples of
formulations for the air freshening composition can be found in
U.S. patent application Ser. No. 15/094,542, which is hereby
incorporated by reference in its entirety.
[0049] Although this invention has been described in certain
specific exemplary embodiments, many additional modifications and
variations would be apparent to those skilled in the art in light
of this disclosure. It is, therefore, to be understood that this
invention may be practiced otherwise than as specifically
described. Thus, the exemplary embodiments of the invention should
be considered in all respects to be illustrative and not
restrictive, and the scope of the invention to be determined by any
claims supportable by this application and the equivalents thereof,
rather than by the foregoing description.
INDUSTRIAL APPLICABILITY
[0050] The invention described herein can be used in the commercial
production of a pressurized dispensing system. Such pressurized
dispensing systems have a wide variety of uses, for example, in the
market of aerosol products.
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