EP0375727B1

EP0375727B1 - Improved aerosol container closure

Info

Publication number: EP0375727B1
Application number: EP88907914A
Authority: EP
Inventors: Robert Henry Abplanalp; Barry M. Connell
Original assignee: Individual
Current assignee: Individual
Priority date: 1987-05-07
Filing date: 1988-06-22
Publication date: 1993-11-18
Anticipated expiration: 2008-06-22
Also published as: EP0375727A1; KR970005138B1; EP0375727A4; KR900006202A; PT87439A; CA1315217C; NZ224538A; PT87439B; GB2206650A; ZA883263B; GB2206650B; AR240158A1; GB8810700D0; ES2008468A6; WO1989012583A1; ATE97377T1

Abstract

A valved-closure for an aerosol container having a bonding agent (10) disposed between the gasket (116) and the mounting cup (118). Further laminated metal and polymer layers having a bonding agent (10) disposed between the laying in strip (12) form.

Description

The present application relates to a gasketed mounting cup as defined in the preamble of claim 1, the tubular gasket material itself as defined in the preamble of claim 7 and a method of applying said tubular gasket material on said mounting cup as defined in claim 13.

Background

Aerosol dispensing containers have found widespread use in the packaging of fluid materials including a variety of both liquid 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 dispensed. Because the propellant has an appreciable vapor pressure at room temperature, the product in the closed container is maintained under super-atmospheric pressure.
A typical aerosol unit comprises a hollow cylindrical container which is tightly closed at one end and is provided with an opening at its opposite end for receiving a dispensing valve assembly. A closure, commonly referred to as a mounting cup, serves as the closure for the container and as a support 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 of 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 opening 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 adequate sealing between the closure and the container, the cup is provided with a gasket in the channel, or predominantly in the channel of the cup.
Heretofore, mounting cup seals 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 seal may be less effective.
Another commercial method for disposing the gasket onto the mounting cup consists in forming the gaskets in situ from liquid gasket-forming compositions comprising an elastomer dispersed or dissolved in volatile liquid vehicles, so called "flowed-in" gasket. In the manufacture of such a gasket, the liquid 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 flows. The deposit is then converted into a dry solid sealing mass by expelling the liquid vehicle at elevated temperatures. Though this technique of flowing 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 so as to avoid undue upset from the horizontal; costly recovery apparatus for the expelled liquid also must be provided. In sum, the flowed-in gasket is an expensive step in the formation of the mounting cup. See United States Patent No. 3,342,381 as an example of the "flowed-in" gasket.
Other techniques for disposing a gasket onto the mounting cup are described in United States Patent No. 3,417,177, wherein the gasket seal is made of heat shrinkable material. After placing a band of gasket material on the skirt, the gasket having a greater diameter than the outside diameter of the skirt of the mounting cup, the cup is heated at a temperature and for a time sufficient to shrink 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 of a suitable swelling agent so as to increase its diameter to fit over the skirt of the mounting cup. Subsequently, the swelling agent is removed from the gasket material so that the band will come into tight frictional engagement with the skirt.
Both the heat shrink and swelling 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 tight friction fit. In the procedure of 3,443,006, the bands must stand in the swelling liquid for a period of 1/2 to 1-1/2 minutes according to example 2 of the '006 patent and then allowed 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 system, including novel method and apparatus, wherein the gasket material is disposed on the mounting cup 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 techniques of applying the gasket material 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 aligning the skirt of the mounting cup and the contiguous end of the mandrel such that the sleeve of gasket material may pass onto the skirt, 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 such that the gasket material passes onto the skirt of the cup; causing the moveable portion of the mandrel to retract to its initial position, cutting the sleeve at a point between the mounting cup and the mandrel to leave a band of gasket material; and subsequently, advancing 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 mounting cups.
Subsequently, the gasket is advanced to the ultimately desired position on the mounting cup.
For certain applications of the gasketed mounting cups of United States Patents Nos. 4,546,525 and 4,547,948, namely, utilizing said mounting cups in so-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 filling operation.
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 United States Patent No. 4,559,198.
The invention disclosed in United 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 stabilizing the gasket material on the mounting cup during "under the cup" propellant filling, some problem remained with stabilizing the gasket relative to the desired position on the mounting cup, engendered, in part, by the 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 temperature-activable bonding material between the surface of the gasket contiguous to the mounting cup and the mounting cup as defined in the characterizing portion of claim 1, which temperature-activable bonding material acts to adhere the gasket to the metal mounting cup; as well as the sub-combination of the gasket material and the temperature-activable bonding material, per se. In a particular and preferred embodiment the temperature-activable bonding material is disposed in a stripe form on the surface of the gasket material. Preferably, the temperature-activable bonding material must have a temperature-activated range such that it will be non-tacky or non-adhering to the 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 so as to form an apex of the bonding material furthest away from the gasket material.
The present invention will be more clearly understood by referring to the drawings herein and the discussion relating thereto.
In the drawings:
Figure 1 is a partial sectional view of the gasketed aerosol mounting cup showing the gasket and bonding material 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 is an enlargement of the circled portion of Figure 2.
Figure 4 is a plan view of the gasket material of this invention.
Figure 5 is an enlargement of the circled portion of Figure 4.

Description of the Invention

Figure 1 shows the position of the gasket on the mounting cup at an initial stage of advance.
The gasket may be initially positioned on the mounting cup in accordance 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 said Figures, which Figures and description is incorporated into and made a part of the description of this invention.
Subsequent to the initial advance of the gasket material onto the skirt of the mounting cup, the mounting cup is passed on conventional tracking through a zone wherein the band of gasket and bonding material is heated by conventional heating means through heat exchange with the mounting cup. For example, the heating zone is a conventional 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 of 200-225F°, preferrably a temperature of 218-225°F has been found satisfactory.
Alternatively, and preferably, the mounting cup is heated by a conventional radio frequency system (RF.)
From the heating zone the mounting cups are passed to a secondary plunger station for final positioning of the gasket. The plunger for advancing 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 sleeve portion 122 defining a recess 128. Within the recess 128 is a mounting cup stripping 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 from the head portion 124 by a spring 138. Mating portion 132 of the mounting cup stripping member 130 is biased away from the head portion 124 by a spring 140. Mating portion 134 of the mounting cup stripping member 130 is biased away from mating portion 132 by spring 142.
The sleeve 122 has a lower portion 144 having an annular shoulder 146. The shoulder portion 146 engages the gasket material 116 while advancing the gasket to its ultimate position on the mounting cup 118.
In operation, the mounting cups 118 are suitably placed at the secondary plunger station. 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. Also the mounting cup stripping member 130 is brought into contact with the cup, as shown in Figure 2. Upon advancing the plunger 120, the sleeve 122 moves to engage the shoulder 146 against the gasket material 116 and urge the gasket material 116 further onto the skirt 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 of the channel of the mounting cup.
During retraction of the plunger 120, the mating portion 134 of 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 mating portion 132 to advance toward mating portion 134 during the advance of the plunger 120.
Preferably, following the advancement of the gasket material to its ulitmate position on the mounting cup, the gasketed mounting cup is cooled to room temperature.
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 there is 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 g/cm³) plus stablizers usually used with polyethylene in the environment in which the gasket material will reside, provides a satisfactory gasket material over a broad product range.
The gasket material bearing the temperature-activable bonding material is ideally extruded in continuous 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 the gasket material may be applied to the mounting cup as individual bands of gasket material.
Preferably, the gasket material bearing the temperature-activable bonding material on its inner surface for adhering the gasket and mounting cup is manufactured utilizing conventional coextrusion or other methods of application. The bonding material may be applied to the entire surface of the gasket material that is contiguous to the mounting cup, but is preferably disposed in stripe 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 stripes be used and that the stripes be uniformly distributed on the gasket material. It has been found that using six stripes provides an effective bonding of gasket and mounting cup.
Figure 4 shows the gasket material of this invention having the stripes 10 disposed on the inner surface 11 of the gasket material, generally designated as 12.
Figure 5 shows in enlarged detail the preferred shape 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 in the stripes of bonding material that the heat transfer from the heated mounting cup to the temperature-activable bonding material is 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 fit between gasket and mounting cup, or a combination of both adhesion and interference fit.
While the temperature-activable bonding material may be any adhesive resin compatible with the gasket material chosen and other components and product of the aerosol container, it has been found that BYNEL™ CXA 2002 (a trademarked product sold by E.I. Du Pont De Nemours & Co, (Inc.) is preferable for use with the aforesaid polyethylene gasket material.

BYNEL CXA 2002 is an ethylene terpolymer containing a temperature stable ester in combination with high acid functionality. Typical property data for BYNEL CXA 2002 is as follows:

Melt Index dg/min., ASTM D-1238	10
Density kg/m³ (g/cc), ASTM D-1505	931 (0.931)
Melting Point °C(°F), DSC	91 (196)
Freezing Point °C(°F) DSC	66 (150)
Vicat Softening Point °C (°F), ASTM D-1525	44 (111)
Tensile Strength mPa(psi) ASTM D-1708	47.8 (6940)
Tensile Modulus mPa (psi) ASTM D-1708⁽¹⁾	22.3 (3240)
Elongation at Break %, ASTM D-1708	730

It is important that the temperature-activable bonding material have the capability of being converted to the bonding state at a temperature below the distortion temperature 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, so as not to deposit said substance onto the skirt portion of the mounting cup as the gasket is advanced to its ultimate position during the secondary plunger action.

Claims

A gasketed mounting cup (Fig. 1) comprising a panel, a skirt (118) 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 a tubular gasket material (116) is first disposed as a band on the skirt of said mounting cup, and is then advanced partially into said channel, such that the gasket is disposed from below the clinch point of the skirt into the channel, characterized in that a temperature-activable bonding material is disposed on the surface of the gasket material contiguous to the mounting cup, which temperature-activable bonding material assists, after activation by heating, in adhering the gasket to the skirt and channel of the mounting cup.
The mounting cup of claim 1, wherein the temperature-activable bonding material is disposed on the surface of the gasket material contiguous to the mounting cup by coextruding the gasket material and the temperature-activable bonding material.
The mounting cup of claim 1, wherein the temperature-activable bonding material is disposed between the gasket and the mounting cup in the form of a plurality of stripes.
The mounting cup of claim 2, wherein the temperature-activable bonding material is disposed on the surface of the gasket material contiguous to the mounting cup in the form of a plurality of stripes.
The mounting cup of claim 3, wherein the plurality of stripes disposed between the gasket material and the mounting cup are substantially equally spaced from each other.
The mounting cup of claim 3, wherein six stripes of temperature-activable bonding material are evenly spaced on the gasket material.
A tubular gasket material (116) suitable for gasketing an aerosol mounting cup to a container bead, said mounting cup comprising a panel, a skirt (118) 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, said gasket material (116) having an inner surface for bearing against the mounting cup in an initial position on the skirt of said mounting cup and in a final position partially within the channel of said mounting cup, characterized in that a temperature-activable bonding material is disposed on the inner surface of the gasket material for adhering after activation by heating, at least in part, the gasket to the skirt and channel of the mounting cup.
The gasket material of claim 7, wherein the gasket material and temperature-activable bonding material are coextruded.
The gasket material of claim 7, wherein the temperature-activable bonding-material is disposed on the inner surfce of the gasket material in the form of a plurality of stripes.
The gasket material of claim 9, wherein the stripes of temperature-activable bonding material are shaped such that an apex of bonding material is formed in that portion of the stripe furthest from the gasket material.
The gasket material of claim 9, wherein the stripes of temperature-activable bonding material are evenly spaced on the inner surface of the gasket material.
The gasket material of claim 11, wherein the stripes of temperature-activable bonding material are shaped such that an apex of bonding material is formed in that portion of the stripe furthest from the gasket material.
A process for attaching a tubular gasket to a mounting cup wherein the mounting cup comprises 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, wherein said gasket comprises a temperature-activable bonding material which activates at a particular activation temperature on the surface to be contiguous to the mounting cup, said process comprising the steps of;
placing said gasket on said skirt at a temperature below the activation temperature of the temperature-activable bonding material;
advancing said gasket along said skirt, partially into said channel; and
increasing the temperature of the mounting cup to activate said temperature-activable bonding material to assist in adhering said gasket to said skirt and channel of said mounting cup after said gasket is advanced to its final position.
The process of claim 13, comprising first disposing said temperature-activable bonding material on the surface of the gasket material to be contiguous to the mounting cup by coextruding the gasket material and the temperature-activable bonding material.
The process of claim 13, comprising disposing said temperature-activable bonding material on the gasket in the form of a plurality of stripes (Fig. 4).
The process of claim 14, comprising disposing the temperature-activable bonding material on the surface of the gasket material in the form of a plurality of stripes (Fig. 4).
The process of claim 15, wherein the stripes of temperature-activable bonding material are substantially equally spaced form each other (Fig. 4).
The process of claim 15, wherein six stripes of temperature-activable bonding material are evenly spaced on the gasket material (Fig. 4).