Note: Descriptions are shown in the official language in which they were submitted.
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IMPROVED AEROSOL CONTAINER CLOSURE
Ba ck~round
Aerosol dispensing containers have found widespread use in
the packaging of fluid materials including a variety of b~th
liguid and powdered particulate products. Such containers are
provided with a valve-controlled discharge orifice and operate by
the action of a volatile propellant which is confined within the
container together with the product to be di~pensed. Because the
propellant has an appreciable vapor pressure at room temperature~
the product in the closed container is ~aintained under supPr-
at~ospheric pressure~
A typical aerosol unit comprises a hollow cylindrical
container which i~ tightly closed at one end and is provided with
an opening at its opposite end for receiving a dispensin~ valve
assembly. ~ closure, commonly referred to as a mounting cup,
serves as the closure for ~he container and as a 6upport for the
valve assembly. Typically, the mounting cup comprises a panel
portion having an aperture for receiving the valve unit, a skirt
portion depending from the periphery o~ the panel, and an annular
channel portion extending outwardly from the edge of the skirt.
When the mounting cup is placed in sealing position on the
container, the channel is positioned over the bead surrounding
the container openin~ and the lower portion of the skirt
adjacent to the channel is flared or clinched outwardly against
the container wall adjacent the bead. To ensure adPquate sealing
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~tween the closure and the container, the cup is provided with a
gasket in the channel, or predominantly in the channel of the cupO
Heretofore, mounting cup ~eals have been formed by disposing
a so-called ~cut~ gasket in the channel. This type of gasket has
the disadvantage of not being stationary relative to the mounting
cup during propellant filling or other valve unit assembly
operations with the undesirable consequence that when the mounting
cup and container are clinched to effect the seal, the gasket is
often disposed at an angled position, and thus, the ~eal may be
less effective.
Another commercial ~ethod for disposing the gasket onto the
mounting cup consists in forming the gaskets in ~itu from liquid
gasket-forming compositions comprising an elastomer dispersed or
dissolved in volatile liquid vehicles, 80 called ~flowed-in~
gasket. In the manufacture of ~uch a gaske~, the liguid
composition is deposited in the desired configuration in the
channel of the cup while the cup is rotated beneath a metering
nozzle through which the gasket composition fl~ws. The deposit
is then converted into a dry solid sealing mass by expelling the
liquid vehicle at elevated te~peratures. Though thîs technique of
~lowing gaskets into place has received wide commercial
acceptance, it suffers from the disadvantages of requiring an
elaborate'drying operation, wherein the mounting cup must be
handled carefully 60 as to avoid undue upset from the horizontal;
costly recovery apparatus for the expelled liquid also must b~
provided. In sum, the flowed-in gasket is an expensive step in
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the f~rmation of the m~unting cup. See U~ited s*ates Patent N~.
3, 342, 381 as an example of the ~flowed-in~ gasket.
Other techniques for disposing a gasket onto the m~unting
cup are described in United states Patent N~. 3,417,~77, wherein
the gasket ~eal is made of heat shrinkable material. After placing
a band of gasket ~aterial on the ~ir~, the gask4t having a
greater diameter than the outside diameter of th~ skirt of the
mounting cup, the cup is heated at a temperature and for a time
sufficient to ~hrink the band into tight frictional engagement
with the skirt.
Another similar technique is that disclosed in United States
Patent No. 3,443,006, wherein a band of gasket material is swelled
through the use o~ a suitable ~welling agent ~ ~s to increase its
diameter to fit over the skirt of the m~unting ~up. Subsequently,
the swel-ing agent is removed from the gasket ~aterial ~o that
the band will come into tight frictional ~ngagement with the
skirt.
Both the heat shrink and ~welling techniques for applying a
gasket material to the mounting cup have the disadvantage of
being costly and relatively time consuming procedures. Note in
U.S. 3,417,177, column 4. lines 27~31/ that the positioned bands
must be heated to 240-F for about 2-3 minutes in order to obtain
a ~ight friction fit. In the procedure of 3,443,006, the hands
must stand in the swel~ing liquid for a period ~f 1~2 to 1~
minutes according to example 2 of the '006 patent and then allowed
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to stand for the drying period. Also, in any mass production
utilizing the ~006 system, an organic liquid recovery system must
be employed.
In the United States Patent Nos. 4,546,525 and 4,547,948 is
described a novel gasketed mounting cup ~ystem, including novel
method and apparatus, wherein the gasket material is disposed on
the mounting Cl'p in the preferred position for effecting a seal
between the mounting cup and the bead of the container; and
further wherein the disadvantages associated with the
aforementioned techni~ues of ~pplying the yasket mat~rial to the
cup are obviated. Also, an apparatus and method is provided
wherein gaskets are applied to aerosol mounting cups in an
exceptionally rapid and efficient manner to form gasketed-mounting
cups having excellent sealing characteristics.
In general, the method of the invention of the aforesaid
United States Patent Nos. 4,546,525 and 4,547,948 comprises
passing a tubular sleeve of gasket material onto a compressible
mandrel; initially positioning and.~ligning the fikirt of the
mounting cup and the contiguous end of the mandrel such that the
sleeve of gasket material may pass onto the ~kirt, said mandrel
having fixed and moveable portions with respect to each other and
to their movement toward and away from the mounting cup; urging
the moveable portion of the gasket material bearing mandrel toward
the mounting cup ~uch that the gasket material passes onto the
skirt of the cup; cau~ing the moveable portion of the mandrel to
retract to its initial position, cutting the sleeve ~t a point
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between the mounting cup and the ~andrel to leave a ban~ of gasket
material; and subseguently, advancinq the mounting cup to a
station whereat the band of the gasket material is urged further
onto the skirt. of the mounting cup, whereby, the band of gasket
material does not extend beyond the skirt of the mounking cups.
Subsequently, the gasket is advanced to the ultimately desired
position on the mounting cup.
~ or certain applications of the gasketed ~ounting cups of
United States Patents Nos. 4,546,~25 and 4,547,948, namely,
utilizing said mounting cups in 60-called, ~under the cup~
propellant filling of the container, it was observed that on
limited occasions the gasket band was displaced from the desired
position on the mounting cup during the ~illing operationO
An improvement in the method and apparatus utilized in United
States Patent Nos. 4,546,525 and 4,547,948 and the cup produced
thereby was provided by the invention disclosed in Unite~ States
~atent No. 4,559,198.
The invention disclosed in Uni~ed States Patent No. 4,559,198
comprises forming one or more compressive deformations in the
band of gasket material.
While the invention of United States Patent No. 4,559,198
provided an improvement in ~tabilizing the gasket material on the
mounting cup during ~under the cup~ propellant filling, some
problem remained with ~tabilizing the gasket relative to the
desired position on the, mounting cup, engendered, in part, by the
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variable conditions encountered during the propellant filling
operations.
Summary of the Invention
Broadly stated in its relation to an aerosol container
closure, the invention comprises a gasketed mounting cup having a
temp~rature-activable bonding material between the surface of the
gasket contiguous to the mounting cup and the mounting cup, which
temperature-activable bonding material acts to adhere ~he gasket
to the metal mounting cup; as well as the sub-combination of the
gasket material and the temperature-activable bondiny material,
per se. In a particular and preferred embodiment the temperature-
activa~le ~onding material i5 disposed in a ~tripe form on the
surface Qf the gasket material. Preferably, the temperature-
activable bonding material must have a temperature-activated
range ~uch that it will be non-tacky or non-adhering to t~e
mounting cup during initial placement on the mounting cup and
convert to a tacky or adhering state when the gasket material is
disposed in its ultimate position on the mounting cup. In a
still more particular and more preferred form, the stripe of
temperature-activable bonding material is shaped o as to form an
apex of the bonding material furthest away from the gasket
material.
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In accordance with one aspect of the invention there is
provided in a gasketed mounting cup comprising a panel, a
skirt integral with and depending from the periphery of said
panel, said skirt being outwardly flared to form an annular
channel for mating with the bead of a container opening and
wherein the gasket material is disposed as a band on the skirt
from below the clinch point into the channel, the improvement
which comprises disposing a temperature-activable bonding
material between the surfacs of the gasket material contiguous
to the mounting cup, which temperature-activable bonding
material assists in adhering the gasket to the mounting cup.
The present invention will be more clearly understood by
referring to the drawings herein and the discussion relating
thereto.
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In the drawings:
Figure 1 is a partial sectionai view of the gasketed aer~sol
mounting cup ~howing the gasket and bonding ~aterial in a
partially advanced position on the skirt of the mounting cup.
Figure 2 is a partial sectional view of the apparatus used
to advance the gasket and bonding material from an initial
position on the mounting cup to its ultimate position on the
mounting cup.
Figure 3 i5 an enlargement of the circled portion of Figure
2.
Figure ~ is a plan view of the gasXet material of this
invention.
Figure 5 is an enlargement of the circled portion of Figure
4.
Description of the Invention
Figure 1 shows ~he position o~ the gasket on the mounting
cup at an initial stage of advance.
The gasket ~ay be initia~ly positioned on the mounking cup in
acc~rdance with the method and apparatus described in United
States Patent No. 4,559,198, at Figures 1-10 and the description
in said patent referring to ~aid Figures, which Figures and
description is incorporated into and made a part of the
description of this inv,ention.
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Subsequen~ to ~he ini~ial advance ~f the gasket material
onto the E;kirt of ~he mounting cup, the mounting cup is passed on
conventional tracking through a zone wherein the band of gasket
and bonding material is heated by c~nventional heating means
through heat exchange with the mounting cup. For exa~ple, the
heating zone is a conYentional mounting cup tracking in indirect
heat exchange with an insulated heated water system, said water
system being capable of close control through heated water control
systems. Heating the mounting cup to a temperature ~f 200-225F,
preferrably a temperature of ~18-225-F has been found
satisfactory. Alternatively, and preferably, the mounting cup is
heated by a conventional radio ~requency system (RFo)
From the heating zone the mounting cups are passed to a
~econdary plunger ~tation ~or final posi~ioning of the gasket.
The plunger for ad~ancing the gasket at the secondary plunger
station is shown in Figure 2.
The plunger of Figure 2, generally designated as 120,
comprises an outside sleeve portion 122, a head portion 124, a
chuck portion 126, which chuck portion is attached to a plunger
advancing mechanism (not shown), the head portion 124 and ~leeve
portion 122 defining a recess 12~. Within the recess 128 is a
mounting cup 6tripping member, generally designated as 130, which
comprises slidably mating portions 132 and 134, and a mounting
cup centering member, 136, which centering member 136 is biased
away ~rom the head portion 124 by a spring 138. Mating portion
132 of the mounting cup stripping member 130 is biased away from
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_.le head portion 124 by a spring l~Oo Mating portion 134 of the
mounting cup ~tripping member 130 is biased away f rom mating
porti~n 132 by spring 142.
The sleeve 122 has a lower pGrtion 144 hav.ing an annular
shoulder 146. The shoulder portion 146 engages the gasket
material 116 while advancing the gasket to its ultimate position
on the m~unting cup 118.
In operation, the mounting cups 118 are suitably placed at
the secondary plunger ~tation. When in place, the plunger 120 is
advanced toward the mounting cup 118 by centering the cup relative
to the plunger 120, the mounting cup centering member 136 serving
this function. Al~o the mounting cup stripping me~ber 130 i5
brought into contat with the cup, as hown in Figure 20 Upon
advancing the plunger 120, ~he sleeve 122 moves to engage the
shoulder 146 against the gasket material 116 and urge the gasket
material 116 further onto the 6kirt of the mounting cup 118,
ultimately advancing the gasket material to the final position
shown in Figure 2. As shown in Figure 2, the edge 148 of the
sleeve 122 terminates its advance by bottoming against the walls
152 of the channel of the mounting cup.
During retraction of the plunger 120, the mating portion 134
o~ the mounting cup stripping member 130 is biased against the
mounting ;cup 118 by the spring 142 until such time as the sleeve
122 moves clear of the advanced gasket, thus precluding the
retracting sleeve 122 from lifting the mounting cup 118.
Obviously, the.springs 140 and 142 must be designed to permit
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mating portion 132 ~o advance ~oward mating portion 134 during the
advance of the plunger 1200
~ referably, following the advanoement of the gasket material
to its ulitmate pQSi~ion on ~he mounting cup, the gasketed
mounting cup is cooled to room temperatureO
To form a friction fit between gasket material and the skirt
of the mounting cup, the inside diameter of the gasket material
is slightly less than the outside diameter of the skirt portion
of the mounting cup.
While any plastic gasket material having sufficient
resiliency may be used provided that t~ere i6 compatability
between the container contents and the plastic material, it has
been found that a plastic comprising linear low density
polyethylene (density range of ~916-.922) plus st~blizers usually
used with polyethylene in the environment in which the gasket
material will reside, provides a ~atisfactory gasket material
over a broad product range.
The gasket material bearing the temperature-activahle bonding
material is ideally extruded in ~ontinuous tubular form. However,
it should be understood that the temperature-activable bonding
material may be used in conjunction with a pre-formed band of
gasket material and thereafter applied ~o the mounting cup as
individual bands of gasket material.
Preferably, the gasket material bearing the temperature-
activable bonding material for adhering the gasket and mounting
cup is disposed on the inner surface of the gasket material and
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is manufactured utilizing conventional coextrusion or other
methods of application. The bonding material may be applied to
the en~ire surface of the gasket material that is contiguous to
the mounting cup, but is preferably disposed in 6tripe form on
the gasket, and more preferably formed as stripes having an apex
in that portion of the bonding material distal to the gasket
material. It is preferable that a plurality of ~tripes be used
and that the stripes be uniformly distributed on the gasket
material. It has been found that using ~ix ~tripes provides an
effective bonding of gasket and mounting cup.
Figure 4 ~hows the gasket ~aterial of this invention having
the stripes 10 disposed on the inner surPace 11 of the gasket
material, generally designated as 12.
Figure 5 ~hows in enlarged detail the prefer~ed ~hape of the
stripes of bonding material. Note the formation of the apex 13
in the bonding material distal to the gasket material 12. It is
believed that by providing an apex ln the ~tripes of bonding
material that the heat transfer from the heated mounting cup to
the temperature-acti~able bonding material i~ best controlled and
maximized.
The temperature-activable material forming the bond between
the gasket and mounting cup may result in the formation of an
adhesive bond, a stronger interference ~it between gaske~ and
moun~ing cup, or a combination of both adhesion and interference
~it .
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While the temperature-activable bonding material may be any
adhesive resin compatible with the gasket material chosen and
other components and pr~duct of the aerosol container, it has
been found that ~YN~L~ CXA 200~ (a trademarked product sold by
E.I. Du Pont De Nemours ~ Co, ~Inc.) is preferable for use with
the aforesaid pol~ethylene gasket material.
BYNEL CXA 2002 is an ethylene terpolymer containing a
temperature stable ester in combination with high acid
functionality. Typical property data fsr BYNEL CXA 200~ is as
follows:
Melt Index dg/min., 10
ASTM D-1238
Density kg/m3 (g/cc), 931 (0.931)
ASTM D-1505
Melting Point 'C('F), DSC 91 (196)
Freezing Point ~C(-F) DSC 66 (150)
Vicat Softening Point C 44 (111)
(-F), ASTM D-1525
Tensile Strength mPa(psi) 47.8 (6940
ASTM D~1708
Tensile Modulus mPa (psi~ 22.3 (3240)
ASTM D-1708(1)
Elongation at Break ~, 730
ASTM D-1708
It is important that the temperature-activable bonding
material have the capability of ~eing converted to the bonding
state at a temperature below tne distortion tempera~ure of the
gasket material. Preferably, the temperature that converts the
bonding material to the bonding state is at or near that generated
by the heated mounting cup when the gasket is at its ultimate
position on the mounting cup, 50 as not to deposit said substance
onto the skirt portion of the mounting cup as the gasket is
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_~vanced to its ultimate position during the secondary plunger
action.
That aspect of the subject invention regarding disposing the
temperature-activable bonding material in striped fo~m on the
surface of the gasket material; and more preferably in striped
form with an apex distal to the gasket material surface, has
utility in bonding materials generally. For example, the striped
form may be used to bond a laminate of plastic material to a metal
or other ~urface.
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