WO1989000538A1

WO1989000538A1 - Improved aerosol container closure

Info

Publication number: WO1989000538A1
Application number: PCT/US1988/002489
Authority: WO
Inventors: Barry M. Connell
Original assignee: Precision Valve Corporation
Priority date: 1987-07-21
Filing date: 1988-07-21
Publication date: 1989-01-26
Also published as: EP0328582A1; EP0328582A4; BR8807138A; DK138389D0; ES2011667A6; FI891326A0; PT88065A; AU2134088A; KR890701450A; ZA885239B; GB8817300D0; FI891326A; NZ225486A; GB2208308A; AR240159A1; DK138389A; JPH02500825A

Abstract

Aerosol dispensing containers have found widespread use in the packaging of fluid materials. Because these containers are maintained under super-atmospheric pressure there has typically been problems with leakage at their mounting cups. The present invention prevents leakage by providing a gasketed mounting cup (10) for an aerosol container having a rigid, substantially non-deformable, annular indent or depression (24) in the outer wall of the channel portion (18) of the mounting cup.

Description

IMP OVED AEROSOL CONTAINER CLOSURE 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 pedestal portion for mounting the valve unit, a panel portion extending from the pedestal portion, a skirt portion depending from the periphery of the panel, and an annular channel portion extending outwardly from the skirt. When the mounting^s 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 "cut¹¹ 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.

In addition to the type of mounting cup gasket systems described heretofore, namely, "cut", "flowed- in" and "sleeve" gasket, a recent commercial system involves laminating a plastic material to a sheet of the metal and subsequently forming the laminated plastic sheet into a mounting cup. The thickness of the plastic laminate is usually on the order of .008- 010", thinner than the sleeve gasket and substantially thinner than the cut or flowed-in gasket.

This variation in gasket thickness among the several gasket systems further complicated by the fact that the channel portion of the mounting cups manufactured by the valve assembly plants and the annular beads of the aerosol container manufactured by container plants have nominal variations which are within quality control limits, often produce a defective seal in a completed aerosol product which y remain undetected until discovered by the ultimate consumer.

Although various proposals have been made in the prior art to improve the seal between the peripheral rim of the mounting cup and the annual bead of the aerosol container, little effort has been undertaken to improve the shape or configuration of the mounting cup. The seal between the channel portion of the mounting cup and the annular bead of the aerosol container remains of great concern to both the valve assembly plants and the filling plants since the seal between the mounting cup and the aerosol container must be capable of being gas tight for a period of years. In addition, the seal between the mounting cup and the aerosol container must be low in cost to enable aerosol products to be competitive with non- aerosol products in the consumer market.

Recently, a modification of the shape and configuration of the mounting cup used over the past twenty-five years in the aerosol industry was described in International Application Number: PCT/US86/01068. This modification of the mounting cup comprises a channel portion for sealing with the bead of the container. The channel portion having an inner region contour being substantially different in shape from the inner surface contour of the annular bead of the container. The difference in the shape of the inner region contour of the channel portion from the shape of the inner surface contour of the annular bead allows only a portion of the inner region contour of the peripheral rim to contact the inner surface contour of the annular bead when the mounting cup is disposed on the container. The shape of the inner region contour of the peripheral rim is deformed when the mounting cup is crimped to the annular bead of the container. The deformation of the inner region contour reforms the shape of the inner region contour to be substantially the same shape as the inner surface contour of the annular bead to provide a sealing engagement between the mounting cup and the container."

Summary of the Invention

Broadly stated, this invention comprises a gasketed mounting cup having a rigid, substantially non-deformable, annular indent or depression in the outer wall of the channel portion of the mounting cup.

Preferably, the annular indent is offset from the midpoint (deepest point) of the channel, and more preferably the indent is offset on the channel portion nearer to the skirt portion of the mounting cup. 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 an elevated sectional view of a mounting cup of this invention having a laminated gasket on the surface thereof.

Figure 2 is an enlarged, partial elevated sectional view of that portion of the mounting cup within the circular dotted line of Figure 1.

Figure 3 is an enlarged partial elevated sectional view of the mounting cup of this invention shown clinched onto a partial section of the bead of a container.

Description of the Invention

In Figure 1, the mounting cup generally designated as 10, has a pedestal portion 12 for receiving and retaining a valve unit (not shown) , a panel portion 14, a skirt portion 16, and a channel portion 18 extending from the skirt portion 16. Laminated to the under surface of the mounting cup 10 is a gasket material 20. Disposed interiorly of the midpoint of 22 of the channel portion 18 is an annular indent 24, said indent 24 forming a corresponding protuberance 26 in the gasket material 20.

In Figure 2, the mounting cup 10 components that are shown in partial section have component numbers corresponding to the numbers of Figure 1.

In Figure 3, the mounting cup, generally designated as 10, is shown clinched about the bead 28 of a container (not shown) by outwardly deforming the skirt portion 16 of the mounting cup 10, as shown at 30, said clinching operation being conducted utilizing conventional methods and apparatus familiar to the aerosol industry.

Clinching of the mounting cup and the bead of the container shown effects a compression of the gasket material and thus a sealing force at three zones, namely, the usual seal immediately contiguous to the clinch zone, designated as Zone A in Figure 3; and on each side of the indent/protuberance, designated as Zones B&C. Zones B&C, shown as dotted areas in Figure 3, are generated by the movement of the gasket material during the clinching operation; the nature of the gasket material being such that it retains the volume occupied prior to clinching through movement of the gasket into the space contiguous to the indent/protuberance zone. In contrast to the tapered surface of the mounting cup described in International Application Number PCT/US86/01068, the indent/protuberance of the gasketed mounting cup of the invention essentially retains the indent/protuberance configuration following the clinching of the mounting cup and container bead.

Metal found suitable for use in forming the mounting cup of the subject invention is that currently used in the aerosol industry, namely, tinplate and aluminum, wherein metal thicknesses of .010" & .016", respectively are commonly employed. Suitable gasket materials are those currently utilized commercially in the cut, flowed-in, sleeve and laminated gasket systems.

The annular indent/protuberance of the mounting cup may be formed by conventional tooling.

The dimensions of the annular indent in the mounting cup necessary to retaining the integrity of the indent subsequent to the clinching of the mounting cup and container bead, are the depth and width of the indent. It has been found that an annular indent having a depth of .007" - .010" and a width having a radius of curvature of .020" is satisfactory when utilizing tinplate and aluminum as the metal of the mounting cup and when using a "hold down" force of 100 lbs./sq.in. for tinplate and 125 Ibs./sq.in. for aluminum. Generally, the less rigid the metal, the narrower the width of the indent should be to retain the integrity of the indent during the clinching of the cup to the container bead. Moreover, the depth of the indent should not exceed the thickness of the gasket material and preferably should be less than the thickness of the gasket material.

Further, it is most preferable that the indent in the mounting cup be disposed interiorly of the midpoint of the wall of the channel portion. Disposing the indent at the midpoint of the channel, may result in the deformation of the indent as the clinching head is brought to bear against the mounting cup. Disposing the indent interiorly, that is, nearer to the skirt portion of the mounting cup, as shown in the drawings, is preferable to exteriorly disposing the indent. It has been found that disposing the indent interiorly at 45° from the midpoint of the wall of the channel provides a satisfactory seal.

The cross-sectional shape of the indent is preferably curvilinear, however, other shapes may be employed.

Moreover, a plurality of concentric annular indents may be employed, disposing an indent at the clinch point and the other 30° apart on the radius of curvature of the channel portion.

Claims

What is Claimed:

1. 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 receiving a container bead that defines the container opening, the improvement which comprises forming at least one annular indent in the outer surface of the channel of the mounting cup, said annular indent being dimensionally constructed such that the indent substantially retains its integrity upon clinching of the mounting cup and the container bead.

2. The improved gasketed mounting cup of claim

1, and further wherein the annular indent in the outer surface of the channel is offset from the midpoint of the wall forming the channel of the mounting cup.

3. The improved gasketed mounting cup of claim

2, and further wherein the indent in the outer surface of the channel is offset interiorly of the midpoint of the wall forming the channel of the mounting cup.

4. The improved gasketed mounting cup of claim

3, and further wherein the indent is disposed at approximately thirty degrees from the midpoint of the wall of the channel forming the mounting cup.

5. The improved mounting cup of claim 4, and further wherein the indent has a depth of .007" and a width having a radius of curvature of .020".

6. The improved mounting cup of claim 1, and further wherein a plurality of annular concentric indents are formed in the outer surface of the channel.