Note: Descriptions are shown in the official language in which they were submitted.
BACKGROUND OF THE INVENTION
Field of the Invention
-
This invention relates to fluid sprinkling and more particularly
to an apparatus and method of forming a iluid tight seal between a
mounting cup and an aerosol container.
Description of the Prior Art
The aerosol ;nclustry has undergone dramatic and substantial
changes since the birth of the industry many decades ago. It has
been a constant desire of the aerosol inclustry to increase the
reliability of the aerosol clevices while s;multaneously reducing the
manufacturing ancl the consumer costs of the aerosol device. Each
individual part of the aerosGl device has been investigated in an
attempt to reduce the part cost as well as the cost of assembly of
the aerosol device. The time required to fabrtcate each individual
part as well as time required to fabricate the device, has been
investigated in a continuing attempt to further reduce the cost of
aerosol devices. If a single step in the assembly process can be
accomplished in a shorter period of time~ a substantial reduction in
overall cost will be realized by the increase in production.
2 0 Among the mo5t time consuming steps in the fabrication of an
aerosol valve is the application of a sealing gasket material to the
aerosol mounting cup for sealing with the aerosol container. In
general, the aerosol mounting cup is fabricated by first stamping a
sheet material through a progressive die to form the mounting cup
2 5 turret with a central -throllgh aperture and peripheral sealing rim
~or sealing with an annular bead disposed on the aerosol container.
The stamped mounting cups are oriented for enabling a solvent
based gasket material to be poured into the rim of the mounting
cup. The solvent based gasket material is allowed to set at room
temperature for approximately one hour and is then progressively
passed through three curing ovens. The three progressive ovens
are typically set at 150C, 250C and 350C. The mounting cup is
placed in each oven for approximately one hour in order to remove
the solvent totally from the solvcnt based gasket material an<l to
3 5 leave a solvent residue of rubber to effect the seal between the
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mounting cup and the aerosol cor~tainer. The heated mounting cups
are allowed to cool to proper handling temperature prior to assembly
with the aerosol valve and dip tube. Presently this prior art
process requires approximately four and one-half hours of time for
5 each mounting cup to p~ ovide a suitable coating for sealing with the
aeY osol cor-tainer~ However, since the solvent based gaslcet materiill
is allowed to flow into the moullting cup rim, the resultant solid
residue of rubber i3 irregular in thickness and may result in a
defective seal between the mounting cup and the aerosol container.
Others in the prior art use a precoated process wherein the
~nounting cup stock is unrolled and coated with a gasket material.
The sheet stock is punched and formed to create the aerosol valve
mounting cup. Since the sheet stock is coated prior to forming,
substantial stresses are developed within the coating. In addition,
15 the coating may be damaged during the punching and forming
process .
U. S. Patent 3,417,117 illustrates a sealing gasket for an
aerosol mounting cup formed by positioning a circular band of
heat-shrinkable material over a portion of the skirt of the mounting
2 0 cup . The mounting cup is then heated to shrink the band of
material into frictional contact with the skirt of the mounting cup.
U. S. Patent 3,443,006 pertains to a method of making a
gasketed closure element by s~relling a band of gasket material and
positioning the band of gasket material about the skirt of the
2 5 rnounting cup . The band of gasket material is then allowed to
return to a normal condition to be in frictional engagement with the
mounting cup skirt.
t)thers in the prior art have utili~ed electrostatic spraying of
paints on other coatings, but such processes have not been applied
3 0 to tbe application of sealing gaske-ts .
Although many in the prior art have attempted various methods
to reduce the time required to apply a gasket material to an aerosol
mounting cup, the prior art has heretofore failed to provide an
ine~pensive and reliable method which is a suitable replacement to
35 the solvent based coating and gasket material or the precoated
process which are pr~esently universally used in the aerosol
inclustry.
Therefore, it is an object of this invention to prov;de an
apparatus which overcomes the aforementioned difficulties of the
prior art devices and provides an impro~emen t which is a
significant contribution to the aclvancement of the aerosol art.
Ano-ther object of this invention is to provide an improved seal
between an acrosol container and a mounting cup incorporating the
deposition oF a unifnrm thickness of plastic material on a sealir~g
surface which may be readily cured into a resilient sealing material
to provide a fluid tight seal between the mounting cup and the
aerosol container.
Another object of this invention is to provide an itnproved seal
between an aerosol container and a mounting cup incorpora-ting the
deposition of a preferentially thick~r eoating of plastic material on a
sealing surface with a preerentially thinner coating of plastic
l S material on the remainder of the mounting cup .
Another object of this invention is to provide an improved seal
between an aerosol container ancl a mounting cup wherein the time
required to cure the deposited resilient gasket material is
substantially less than the time required to liberate the solvent of a
2 0 solvent based gasket material of the prior art .
Another object of this invention is to provide an improved seal
between an aer~sol container and a mounting cup wherein a resilient
plastic gasket material is electrostat;cally sprayed onto the mounting
cup to provide a uniform or preferential coating on the sealing
2 5 surface .
Another object of this invention is to provide an improved seal
between an aerosol contain~ar and a mounting cup wherein a resilient
gasket material is deposited on the entire interllal area of the
mounting cup for providing a fluid tight seal between the mounting
cup and the aerosol container as well as protecting the mounting
cup from the procluct internal the aerosol container.
Another object of this invention is to provide an improved seal
between an aerosol container and a mounting cup which may be
colored to provide an integral color code for the mounting cup.
Another object of this invention is to provide an improved seal
between an aerosol container and a mounting cup which
substantially reduces the cost of fabrication of aerosol assemblies.
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Q5
Another object of this invention is to provide a method of
Eabricating an aerosol valve and mounting cup through the use of
electrostatically spraying an individual mounting cup with a resilient
coating and applying heat to cure the resilient coating prior to
5 rece;ving the aerosol valve within the mounting cup.
~ nother object of this invention is to provide a method for
applying a seallng gasket material to a sea1ing surface between a
mounting cup and an aerosol container incorporating electrostatically
spraying plastic material on the sealing surface and the application
10 of heat to cure the pla5tic material into a integral resilient coating.
The foregoing has outlined some of the more pertinerlt objects
of the invention. These objects should be construed to be merely
illustrative of some of the more prominent features and applications
of the intended invention. Many other beneficial results can be
15 attained by applying the disclosed invention in a different manner
or modifying the invention within the scope of the disclosure.
Accordingly, other objects and a fuller understanding of the
invention may be had by referring to the summary of the invention
and the detailed description describing the preferred embodiment in
2 0 addition to the scope of the invention defined by the claims taken
in conJunction with the accompanying drawings.
~L9~
SUMMARY OF THE INVENTION
The invention is defined by the appended claim~ with a
specific embodiment shown in the attached drawings. For the
purpose of summ~ri~ing the invention, the invention may be
5 incorporated into an improved aerosol assembly for an aerosol
container having conta;ner sealing means disposed about an upper
ope~ling in the aerosol container. The invention comprises a
mounting cup havinL~ a mounting cup sealing means e~tending about
the periphery thereof. A valve assembly is disposed in the
10 mounting cup for providing Eluid cornmunication between the interior
of the aerosol container and the exterior of the aerosol container.
A sealing gasket is electrostatically applied on one of the sealing
means for providing a fluid tight se;~l when the mounting cup is
secured to the aerosol container. In a more specific embodiment of
15 the invention, the aerosol container includes a container sealing
bead disposed about the periphery of an opening in the aerosol
container. A rim is disposed about the periphery of the mounting
cup for cooperation ~;7ith the bead of the aerosol container. The
sealing gasket is electrostatically disposed on the interior of the
2 o mounting cup rim for sealing engagement with the bead of the
aerosol container. The sealing gasket may be electrostatically
disposed upon the entire interior surface of the mounting cup for
providing a seal between the mounting cup and the aerosol
container and for protecting the interior of the mounting cup from
2 5 the product internal the aerosol container . In the alternative, the
sealing gasket may be electrostatically disposed upon the entlre
interior and exterior surface of the mounting cup for protecting the
interior and exterior surfaces thereof. Further, the coating may be
applied to provide a preferential thicker coating on the mounting
30 ~.up rim relative to the remainder of the mounting cup. The sealing
gasket may be colored to provide an integral color code for the
mounting cup.
The invention also comprises the method of fabricating an
aerosol valve and mounting cup assembly and the method of
3 5 fabricating an aerosol dispenser comprising the step of stamping the
mounting cup from a metallic sheet material. The method includes
the step of electrostatically spraying the mounting cup with a
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resilient coating, preferablv from a plastic material. Hea-t is applied
to the resilient coating to cure the coating upon tlle mounting cup.
The mounting cup is cooled and the aerosol valve i9 then secured to
the electrostatically coated moun-ting cup. The aerosol dispenser i5
5 further fabricated in the conventional manner.
The foregoing has outline~l rather broadly the more pertinent
and important features of the present invention in order that the
detailed description of the invention that follows may be better
understood so thnt the present contribution to the art can be more
10 fully appreciatecl. Additional features of the invention will be
- described hereinafter which form the subject of the claims of the
invention. It shottld be appreciated by those skilled in the art that
the conception ~nd the specific embodiment disclosed may be readily
utilized as a basis for modifying or designing other structures for
15 carrying out the same purposes of the present invention. It should
also be realized by those skilled in the art that such equivalent
constructions do not depart from the spirit and scope of the
invention as set forth in the appended claims.
BRIEF DESCRIPTION OF THE DRAWINGS
For a fuller understanding of the nature and obJects of the
invention, reference should be had to the following detailed
description taken in connection with the accompanying drawings in
5 which:
Fig. 1 is a side sectional view of a conventional mounting cup
and aerosol valve assembly;
Fig. 2 is a partial side sectlonal view showing the fluid tight
seal between a conventional aerosol valve assembly and an aerosol
10container;
Fig. 3 is a side sectional view of a moun-ting cup and aerosol
valve assembly in accordance with the present invention;
Fig. 4 is a side sectional view of a second embodiment of a
mounting cup and aerosol valve assembly in accordance with the
15present invention;
Fig. 5 illustrates a prior art process for fabricating the
mounting cup shown in Fig. l;
Fig. 6 illustrates the improved method of forming the mounting
cup as shown in Fig. 3 in accordance with the present invention;
2 0Figs . 7-9 illustrate various steps in the electrostatic coating of
the mounting cup shown in Fig. 3;
Fig. 10 is a side sectional view of a third embodiment of a
mounting cup incorporating a preferential coating thiclcness; and
Fig. 11 is a side sectional view illustrating the geometry of
2 5electrostatic spraying to provide the preferential coating thickness
to the mounting cup shown in Fig. 10.
Similar reference characters refer to similar parts throughout
the several views of the drawings.
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DETAILED l~ESCRIPTION
Fig. 1 illustrates a side sectional view of a prior art aerosol
mounting cup and valve assembly 10 which should be well known to
those skilled in the art. I'he assembly comprises a mounting cup 12
5 hav;ng a central turret 14 ancl a mounting rim 1~ extending about
the outer periphery of -the mounting cup 12. The turret 14
receives an aerosol valve assembly which may be of various designs
to operate between an interior surface 17 ancl an e~{terior surface
l8~ Irl this embodiment, a valve body 19 communicates with the
10 interior of the aerosol container through a dip tube 20. A valve 2~
is biased by a spring 24 into sealing engagement with a sealing
gasket 26 for controlling the flow of product and propellant through
a metering orifice 28 communicating to a valve stem aperture 30.
The mounting rim 16 is provided with a sealing gasket 32
15 which is generally a solvent-based rubber material which fvrms a
seal with a bead 34 of an aerosol container 36 as shown more fully
in Fig. 2. Typically, the mounting cup rim 16 is inserted on the
aerosol container bead 34 with the mounting cup rim being deformed
at 38 to form a fluid tight seal tnrough the coating 32 on the
2 0 mounting cup rim 16 .
Fig. 3 illustrates a mounting cup and aerosol valve assembly
10A in accordance with the present invention. Under the practice
of this invention the sealing gasket 32A extends along the entire
interior surface 17 of the mounting cup in addition to being applied
2 5 thereto in an entirely distinct manner . The sealing gasket material
32A may optionally be applied to the exterior surface 18 of the
mounting cup as shown by coating 32B in Fig. 4.
Fig. 5 illustrates the steps in the formation of the mounting
cup 12 shown in Fig. 1 under a prior art practice. A ribbon of
3 0 roll ~tock 41 disposed on a drum 'L2 is passed -through a series of
progressive dies 44 to form the contour of the mounting cup 12
shown in Fig. 1. The formed mounting cups 12 are passe~l through
an orienter 46 which orients the mounting cups 12 such that the
interior surface 17 is face up enabling an applicator 48 to apply a
3 5 solvent based gasket material 32 to flow into the mounting cup rim
16. After the initial coating of the gasket material 32, the
mounting cups 12 are allowed to remain at an ambient temperature
_g_
station 50 for a period of approximately one hour. Ihe mounting
cups 12 are then passed through progressive ovens Sl, 52 and 53
which respectively have temperatures of approximately 150C, 250C
ancl 350C. The mounting cups 12 remain in each of the ovens
51-53 for a period of one hour prior to being removed and cooled in
position 54. After cooling, the mounting cups 12 may be fabricated
in a conventional manner as should he well known to those skilled
in the ar t .
~ig . 6 illustrates the step in the formation of the mo~m ting cup
l2A shown in Fig. 3 under the present invention. In a similar
manner, the ribbon of roll stock 41 is ciisposed on a drum 42 to be
passed through a series of progressive dies 44 to form the contour
of the mounting cup 12A shown in Fig. 3. The formed mounting
cups 12A are passed through an orienter 46A which orients the
mounting cups such that the interior surface 17A is face up and
plased upon conveyor 60 which is preferably a dielectric material as
shown in Figs. 7-9. The conveyor 60 is shown as an endless
conveyor disposed between drive rollers 62 and 64 to automatically
move the mounting cups 12A through an electrostatic coating device
66. In this embodiment, .he conveyor 60 includes a recess 68 for
receiving the contour of the mounting cup 12A and to limit the
coating to only the interior surface 17A of the mounting cup 12A.
It should be appreciated by those skilled in the art that numerous
other types of conveyors may be utilized to coat selective portions
2 5 of the mounting cup 12A or to reorient the mounting cup to coat
both the exterior and interior surfaces 17A and 18A of the mounting
cup 12A as shown in Fig. 4. An electrical conductor 70 is
preferably spring biased into electrical contact to the mounting cup
12A as shown in Figs. 7-9. The electrical connector 70 is
3 0 preferably connected to the positive side of the electrostatic coating
apparatus 66 shown in Fig. 6 with the negative side of the power
supply being connected to the electrostatic spray nozzles 72 in Fig.
6,
The mounting cups 12A are passed through the el~ctrostatic
coating apparatus 66 with charged particulate plastic material being
sprayed from nozzles 72 to be attracted to the mounting cups 12A
by virtue of electrostatic attraction as shown more clearly in Fig.
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8. Upon completion of the coating as shown in Fig. 9, the
mounting cups are discharged along a conveyor 7d5 powered by
rollers 76 and 7B.
The electrostatically coated mounting cups 12A are passed into
a curing oven 80 for approximately 6 minutes at 425F. The
curing oven melts the particulate plastic material into a continuous
resilient gaske-t and protective coating. The completed mounting
cups 12A are removed on conveyor 82 powered by rollers 78 and
84. Whereas thè prior art system shown in Fig. 5 required
approximately four and one-half hours per mounting CUp, the new
process shown in Fig. 6 requires a total of approximately 8 minutes
and provides a superior and more uniform coated sealing gasket 3ZA
than heretofore realized in the prior art. It should also be
appreciated that the electrostatic coating not only provides a sealing
gasket to the rim 16 but also provides a protective coating to the
interior surface 17A to protect the moun~ing cup from the product
and propellant internal the aerosol container. Since the gasket
material is deposited and cured subsequent to the fabrication of the
mounting cup 12A, the resilient sealing gasket is not stressed as in
2 0 one of the prior art processes . Various materials may be used to
coat the mounting cups lZA including polyethylene, polypropylene,
vinyl, nylon, acetate or other powdered plastic materials. The
further advantage of the process resides in the short period of time
required in the o~ren 80. Accordingly, a continuous process oven
may be used to melt the plastic powder to form the coating 32A on
the mounting cup 12A. The mounting cups 12A may be coated on
the interior ancl exterior surface 17 and 18 to provide a protectiv-3
coating or a color coding depending upon the particular application
of the rnounting cup 12A in the aerosol industry. In addition,
various types of electrostatic spraying and orienting devices 46 may
be utilized to accomplish the desired coating of the mounting cup
12~. Preferably, the resilient plastic gasl;et coating 32A has a
thickness between 0 . 010 inches and 0 . 030 inches.
It should be appreciated by those skilled in the art that a
very uniform coating ;s appliecl to the mounting cup surface 12A by
this process. A wide variety of plastics that can be used for
compatibility with the various products and propellants within the
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.5
aerosol container. This invention provides less coating damage than
the precoated prio~ art process wherein a rolled stock is ~mrolled
and epoxy coated with a gasket material~ The coated stock is
rerolled prior to stamping in a progressiYe die. FurtherJ since the
coatirlg efficiency of the electros-tatic process is higher than any
other process heretofore utilized in the aerosol industry ~ the
re.sultant cost of the coating is substantially less than the prior
art. I'he proces.s further eliminates the problem of solvent
èvaporation inlto the atmosphere which may adversely effect the
environment.
Figs. 10 and 11 illustrate a variation of the embodiment shown
in Figs. 3-9. In this embodiment, the combined sealing gasket and
protective coating is preferentially disposed about the interior
surface 17B of the mounting cup 12B shown in Fig. 10.
Preferably, the coating has a greater thickness in the rim 16 as
illustrated by the thickness of the coating 32B as opposed to the
adjacent areas 32C of the mounting cup 12B. Coating areas 32D
and 32E have a greater thickness than the adjacent areas 32F. The
preferential coating thickness as shown in Fig. 10 provides a
2 o thickness of material at 32B sufficient to provide a proper se~l ~,vith
the aerosol container while simultaneously minimizing the amount of
material utilized for coating the entire interior surface 17B of the
mounting cup 12B.
Fig. 11 illustrates the preferred method of forming the
preferential coated mounting cup shown in Fig. 10. In this
emboclimentJ the electrostatic head 100 includes a static chamber 104
which produces a static charge on the plastic particles 106 as the
particles are sprayed therethrough. Accordingly, an electrostatic
powcr source is not required when utilizing this type of
electrostatic spraying device. The term "electrostatic spraying
device" as used in this speciEication contemplates the use of both
electrostatic spraying with an electrostatic power source as well as
electrostatic spraying ~vithout the use of an electrostatic power
source .
The sprayhead 100 is affixed to face in a downward direction
to utilize the force of gravity (G) as indicated by the arrow 108
with the mountlng cup 12B disposed on the conveyor 160 as shown,
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with the interior surface 17B facing upwardly with rim 16 located in
recess 168. The force of gravity as illustrated by the arrow 108
acting on the particles 106 provides a preferential increase in
thickness in areas 32B 32D and 32E in Fig. 10. The spraying
process is adjustecl to enable the thickness of the coating 32B to be
sufficient to provide a suitable seal with an aerosol container at rim
16. Accordingly the coating thickness is preferentially thinner in
at-eas that clo not function as sealing surfaces but :functivn as a
protective coating such as 32C and 32F. The preferential coating
thickness .s~lbstantially reduces the cost ancl increases the reliability
of -the electrostatically sprayed plastic material by utilizing the force
of gravity during the electrostatic spraying process. After the
spraying process is completed as sho~n by 66 in Fig. 6, the
preferentially coated mounting cups 12B n~ay then be processed in
the manner as set forth in Fig. 6.
The prior art mounting cup gasket typically uses a precoated
steel having a one-half pound of tin plate to one hundred pounds of
steel. This material can be secured with the tin plate on either one
or plural sides. The use of the coated mountin~ cup as shown in
2 0 Fig . 3 eliminates the need for a tin coating on the interior surface
17 while the embodiment of Fig. 4 eliminates the need for tin
coating thus further reducing the cost of the materials.
Accordingly, black plate steel may be utilized in lieu of tin plated
steel, depenclin~ upon the process utilized under this invention.
2 5 It should be appreciated by those skilled in the art that the
va~ious embodiments shown in the present specification may be
interchanged and other variations may be incorporatecd within the
present invention without departing from the present contribution to
the art.
The present disclosure includes that contained in the appended
claims as well as that of the foregoing description. Although this
invent:lon has been described in its preferred form with a certain
degree of particularity i-t is understood that the present disclosure
of the preferred form has been made only by way of example and
3 5 that numerous changes in the cletails of construction ancl the
cornbination and arrangeLnent of parts may be resorted to without
departing from the spirit and scope of the invention.
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