US3179309A

US3179309A - Tape valve for pressurized containers

Info

Publication number: US3179309A
Application number: US72181A
Authority: US
Inventors: Paul E Cope
Original assignee: Procter and Gamble Co
Current assignee: Procter and Gamble Co
Priority date: 1960-11-28
Filing date: 1960-11-28
Publication date: 1965-04-20
Anticipated expiration: 1982-04-20
Also published as: GB1001883A

Description

April 2o, 1965 P. E. COPE 3,179,309

`TAPE VALVE FOR PRESSURIZED CONTAINERS Filed Nov. 28. 1960 .23 FIG. 4f.

INVENTOR. PAUL E. COP@ ATTonNY United States Patent O 3 179 309 TAPE VALVE FOR PRESSURIZED CGNTAINERS Paul E. Cope, Cincinnati, Ghio, assigner to The Procter & Gamble Company, Cincinnati, Ohio, a corporation of Ohio Filed Nov. 28, 1960, Ser. N 72,181 6 Claims. (Ci. 2'22--389) A placing a propellant in a container in order to result in a pressurized package is by a pressure filling technique utilizing the dispensing valve as a means of ingress into the container. This is a method wherein the dispensing valve insert unit is sealed to the top of a container previously partially illed with the product to be dispensed therefrom, thereby closing the container, and the valve thereafter is mechanically opened and pressurized propellant forced into the container by reverse flow through the valve. After the proper amount of propellant has been admitted to the container, the dispensing valve is closed and the source of propellant removed. This technique is effective and Works very well in many instances where the propellant is to be carried in a chamber in communication with the dispensing valve. If such is not the case, that is, if the propellant chamber is not in communication with the dispensing valve, obviously another means or diierent technique must be utilized in order to pressurize the container.

A good example of a package in which the propellant is not in communication with the dispensing valve is the oating or free piston type wherein the piston separates the container into two chambers-a product chamber contiguous to the dispensing valve and a propellant chamber in the lower end of the container.

It will be readily realized that the provision of an additional valve, of the same type as the dispensing valve, in a position whereby the propellant may be admitted into the propellant chamber would prove very costly. For this reason it has previously been proposed that the bottom of the container be provided with a filling grommet and that the propellant be introduced into its chamber by piercing the self-sealing grommet with a iilling needle, injecting the propellant into the chamber and then withdrawing the needle from the grommet. This technique is effective and fairly satisfactory at slow production rates. It has been found, however, that the filling needlegrommet method is not particularly well adapted for use with high speed production equipment. f

In order to eliminate some of the above difficulties, other techniques have been tried. Illustrative of such other procedures is the cold filling technique wherein propellant is maintained at very low temperatures and added to the container in liquid form prior to sealing the package closed. A variation of this technique is the depositing of a measured quantity of Dry Ice within a container prior to sealing, thereby providing gaseous CO2 as a propellant upon the sublimation of Dry Ice after the container is maintained at normal temperatures for a period after production of the package. These methods present additional diiliculties since temperature and volume control are quite critical and diiicult to maintain at high speeds and since the cost of refrigeration is substantial. v i

It is an object of the present invention to obviate the above diculties.

Another object of the present invention is to provide an economical and commercially feasible valve for admitting propellant into a container in which the propel- 3,179,309 Patented Apr. 20, 1965 ice laut chamber is not in communication with the dispensing valve, so as to result in a pressurized package.

Brieiiy stated, in accordance with one aspect of this invention, the valve comprises a piece of elastically distensible, substantially liquid and gas impermeable film, Which is coated on one side with a pressure sensitive adhesive and applied over a depression in the internal surface of one wall of a container to be pressurized. The ilm is fastened, by means 'of the pressure sensitive adhesive, to a continuous area of the internal surface of the wall surrounding the depression, and the wall is provided with an aperture terminating at one end in the depressed portion of the internal surface.

While the specification concludes with claims particularly pointing out and distinctly claiming the subject matter which is regarded as forming the present invention, it is believed that the invention will be better understood from the following description taken in connection with the accompanying drawing, in which:

FIGURE 1 is a perspective view partially cut away illustrating an unpressurized free piston type container with a valve of this invention;

FIGURE 2 is an enlarged fragmentary view of the section taken along line 2-2 of FIGURE l;

FIGURE 3 is a fragmentary View in cross-section illustrating the way in which propellant may be forced into the inverted container of FIGURE 1;

FIGURE 4 is a fragmentary perspective View showing the venting of the valve while propellant is being forced into the container as in FIGURE 3; and

FIGURE 5 is an enlarged fragmentary view, similar to that of FIGURE 2, showing the position of the valve after the propellant has been admitted and the sourc of propellant removed. i

A preferred method 'of producing packages of the free piston type comprises seaming a valve and valve cup on a container body of the correct size, inverting the unit thus formed and placing the correct amount of product therein through its open bottom. Thereafter, the piston is inserted in the body and a bottom wall (having a pressurizing valve attached thereto) seamed in place to seal the package.

Referring to FIGURE 1 of the drawing, a container 1t) is shown as being constructed of a seamless cylindrical body 11 having a neck portion 12 at the terminal end of a conelike top Wall 13. A dispensing valve 14 is mounted upon the container 10 by seaming valve insert or cup 15.to neck portion 12. The valve 14 and valve cup 15, which are unitized by crimping the valve 14 within the valve chamber 16 of the valve cup 15, are commercially available units and the details of their ustructure will be understood by those skilled in the art.

Product P, which could be toothpaste, mustard or any Vother type of product desired to be packaged for dispensing from a pressurized container, is located in the upper portion of the container 16 adjacent the dispensing valve 14. A hollow piston 17, comprising contoured face 18 and tapered depending skirt 19, is found within the container 1t) below the product P. The lower end of tapered skirt 19 has an outside diameter which is substantially identical with the inside diameter of cylindrical body 11, thereby providing a snug sliding iit for the piston within container 1). The chamber 20 formed by the hollow interior of piston 17 and bottom Wall 21 seamed to the lower end of cylindrical body 11, is adapted toV receive propellant for moving the piston upwardly to discharge the product P, upon actuation of dispensing valve 14. The contours of face 1S closely match the combined interior surfaces of the container top wall 13, valve 14 and valve cup 15, thereby permitting substantially all of the product P to eventually be dispensed from the container 16 through dispensing Valve i4 at the uppermost limit of piston ll' movement.

The bottom Wall 2li has a hollow or depression 22 formed in a portion thereof. It will be noted that the depression 22 opens to the interior of the container or, stated differently, that the inner surface of bottom wall 21 at the depression 22 is in the form of a concavity. The actual shape of the depression 22 may be any of a number of possible contours.V For example, it could be made to match a portion of the surface of an ellipsoid of revolution, a torus, a cone or a pyramid. Preferably, however, the depression 22 is shaped as shown in FIG- URES l, 2, 3 and 5, i.e., substantially similar to the surface of the zone of a spherical segment of one base (spherical cap). It is also preferred that all changes in contour be gradual in order to minimize the possibility of the concentration of stress along particular lines, and to permit valve element 23 to seat properly following pressurization of the container 10, as will hereinafter be more fully explained. An aperture 24 extends through bottom wall 21 of the container at depressed portion 22, preferably being substantially centrally located therein. As will presently be seen, the aperture 24 serves as a port for the introduction of propellant into chamber 20. It is extremely important that the aperture 24 be free from sharp burrs Where it terminates at the inner surface of depressed portion 22 to avoid puncturing the tape and causing the valve to fail by leakage through the punctures. One method of avoiding such burrs is to punch the aperture through from the inner surface. It is also important that the aperture 24 diameter be small enough to prevent the valve element 23 from being forced through the hole at pressures needed to operate the package. It has been 'found advantageous to size the aperture 24 in the range of 1&2 to 1%4", which is large enough to permit the use of tools of suflicient strength to make production techniques in forming the aperture practical and yet small enough to avoid failure of the valve element 23 as noted above.

Valve element 23 comprises an elastically distensible, substantially gas and liquid impermeable film coated on one side with a layer of pressure sensitive adhesive. It is well known that the pressure sensitive adhesives are composed of an elastomer plus a resin, the elastomer providing the internal strength and the resin the adhesion. Preferably the film or backing may be made of polymerized vinylidene chloride or a modified polyethylene, although any material having the necessary elastomeric and impermeablity properties would be suitable. The coating of pressure sensitive adhesive may also be varied, depending upon the type of propellant to be used and the composition of other substances to which the adhesive will be exposed. For example, if a halogenated hydroi carbon were to be used, due to the solvent properties of this type propellant an extremely careful choice of adhesive would be necessary. In this connection it is noted that some silicone-based pressure sensitive adhesives would be sufhciently resistant to deterioration by such a propellant to be adapted for use in this invention. Gaseous propellants such as carbon dioxide or nitrogen, are preferred for use with the valve of this invention since such would offer less problems in the selection of an adhesive and thus make a broader spectrum of suitable adhesives available. The specific type of adhesive and backing best suited for a particular package or product is, of course, merely a matter of proper selection from many commercially available pressure sensitive tapes.

Depression 22 may be conveniently formed simultaneously with aperture 24 by using a single tool which has an appropriately formed working surface thereon. For the particular embodiment shown, the working surface could be in the form of a spherical cap having a slender punch projecting therefrom. The punch would, of course, have a cross section matching that of aperture 24.

The depth of the spherical depression 22 is preferably small in comparison to the diameter thereof, yet large enough to assure that valve element 23 will not bottom in the depression 22 before the container 10 is pressurized. It has been determined that using a recess and aperture-forming tool having a surface thereon approximating that of a spherical cap of a sphere with a diameter of 0.4, and indenting the bottom wall 21 approximately 0.01", giving a depression 22 diameter of approximately 0.125, has resulted in a depression 22 which is well adapted for use in the present invention. This would be considered a depression ratio (ratio of the depth of depression to the depression diameter) of 0.01/ 0.125 or l/l2.5. Preferably, the depression ratio should be less than l/4 (a quotient smaller than 0.25) so as to permit the use of a great number of the films presently available commercially, and the depth of the depression should be a minimum of approximately 0.003.

FIGURE 2 shows an enlarged fragmentary View of the propellant valve of this invention before propellant is admitted to chamber 20. The valve element`23 is attached to a continuous flat area of bottom wall 2l completely surrounding recess 22 by means of the pressure sensitive adhesive coating 23a. Note that the tape is fairly taut as applied to the bottom wall 23, so tha-t the inner surface of depression 22 is separated from the coating of pressure sensitive adhesive 23a. The tape may be applied to the bottom wall 21 by hand or by using existing automatic equipment to perform the work. By either method, the tape is laid in place and smoothed out on the wall 2l surface, preferably -by rolling. Although the valve is particularly adapted for use in connection with at surfaces surrounding recess 22, it is also feasible to use it on certain other forms of surfaces (for example, on cylindrical surfaces, or on spherical surfaces having a sufficiently large radius of curvature to permit the valve element 23 to be stretched so as to be placed thereon without wrinkles and without setting up internal stresses which when increased by pressurizing stresses would cause failure of the element.)

After the product filled package is completely assembled, as shown in FIGURE l, it is ready to be pressurized. One form of apparatus adapted to perform this function is shown in FIGURE 3 and comprises a metallic plunger 2S with a blind coaxial hole 26 and a counterbore 27 within which is retained a resilient sealing insert 28, preferably a cylindrical rubber tube. A fitting 29 which is fastened to the side wall of the plunger 25 by means which are well known in the art, has a bore 30 therethrough aligned with a passageway 31 communicating with hole 26. Tube 32, which is telescoped over the protruding end of fitting 29, is connected with a source of pressurized propellant and with a valve and control arrangement to regulate the flow of propellant, neither of which is shown in the drawing.

If the propellant is in liquid form, the liquid can be metered or otherwise controlled by volumetric measurement. If the propellant is in gaseous condition, the source thereof can be maintained at the pressure desired in the propellant chamber and the charging controlled by merely balancing the pressures. Of course, many other methods of regulating the quantity of propellant to be introduced into the chamber may be used and it is not implied that the methods disclosed above are the only ones suitable for use with the valve of this invention.

It will be seen that the package to be pressurized is inverted and held in a relatively fixed relationship with plunger 25 by means not shown in the drawing. The plunger 25 is then lowered so that sealing insert 28 encompasses the outer raised surface of depression 22, thus enclosing aperture 24. Suicient pressure is applied to plunger 25 to provide a gas and liquid tight seal between sealing insert 28 and bottom Wall 21. At Vthis point, the valve and control arrangement is actuated, permitting the pressurized propellant to ow into the tube 32,

through bore 30, passageway 31, hole 26 and the interior of sealing insert 28. When the pressurized propellant reaches aperture 24, it is forced therethrough and pressure acts upon the side of the valve element 23 on which the pressure sensitive adhesive coating 23a is found and which overlies depression 22. Since the valve element 23 is not in contact with the inner surface of depression 22, the propellant pressure is free to act upon an area of the valve element 23 which is approximately equal to the largest transverse area of the depression, rather than to act merely upon an area of the valve element 23 equal to the cross sectional area of aperture 24.

The pressure acting upon the valve element 23 forces the area acted upon to bulge inwardly, as shown in FIG- URES 3 and 4, stretching the elastic film and causing a portion of the element 23 to become separated from the bottom wall 21 along a narrow path interconnecting the depression 22 with the propellant chamber 20. The portion of the element 23 thus separated from the bottom wall is also permitted to be distended inwardly by means of the elastic properties of the lm. The elastic limit of the film must exceed the binding strength of the adhesive to avoid permanent deformation of the iilm and likely ultimate failure of the valve. The bulge under the recess and separation along the path above described continues to be present until the source of pressurizing is removed or until the pressure of propellant within the chamber approximately balances that within the recess at which point the elastic properties of valve element 23 cause the element 23 to again seat on the bottom wall 21 at all points surrounding the depression, sealing the propellant within the chamber 20 and causing the pressure sensitive adhesive to become reattached to the bottom wall 21 along the path of prior separation.

As soon as the sealing insert 28 is removed from sealing contact with bottom wall 21, thus venting the aperture 24 to the atmosphere, the pressure of the propellant within the chamber 20 forces the portion of valve element which overlies depression 22 to stretch and conform to the contour of the inner surface of depression 22 thereby becoming adhesively attached thereto by means of the pressure sensitive coating 23a, as shown in FIGURE 5. When the valve element 23 is forced into depression 22, any gas or liquid left in the depression 22 is displaced therefrom through aperture 24.

Thus, it will be seen that the valve of this invention is adapted to high speed production techniques and can be made extremely economically. In this Connection, it should be understood that the valve element 23 and the pressure sensitive adhesive coating 23a thereon now are commercially available combined in tape form. Using an appropirate pressure sensitive tape and equipment now available for cutting and applying pieces of tape to surfaces at high speed will permit the manufacture of the package described above at a cost substantially lower than the -valves previously consideredV economical. Of particular importance is the fact that the tape used does not have to be specially processed or treated in order to permit pressurization and that due to the relatively small size of the depression 22 the registration of the tape over the depression oifers no particular quality control problem in tape placement.

The use of the depression 22 instead of a dat bottom is quite signiiicant from the standpoint of ease in pressurization through valve element 23. As noted above, the depression permits the pressurized propellant to act upon a much larger area of the valve element 23 while retaining an aperture suiiiciently small to prevent the valve from failing. During a series of tests performed with packages of the type shown in FIGURE 1, it was determined that using a recess of the dimensions given previously (i.e., a depression 22 which is approximately 0.01" deep and approximately 0.125 in diameter) with a valve element made of a 1K2 wide by 1 long strip of commercially available 2 mil thick saran backed pressure sensitive tape (marketed by Minnesota Mining and Manufacturing Co. as Saran #490) having a pressure sensitive adhesive on one side, and with a 1/32" diameter aperture in the depression, the instantaneous initial pressure required to cause separation of the element 23 from the bottom wall 21 along the narrow path previously described amounted to slightly more than p.s.i.g.; while a valve element of identical size and construction applied over a lg diameter aperture in a at bottom wall required a pressure approximately 30% higher or about 105 p.s.i.g. It will be understood that a lowerl initial pressure is very desirable for high speed packaging of the type contemplated, permitting greater flexibility in the method of pressurizing and greater speed in performing the operation.

Another advantage is derived through the use of the depression 22 in that the exterior surface of bottom wall 21 underlying depression 22 will usually follow the contours of the depressed portion, thereby providing a rounded and slightly raised exterior surrounding the aperture 24. It has been found that this raised exterior surface area is an aid in properly centering or aligning the container for pressurizing and in obtaining a good seal between the apparatus used to add the propellant and the bottom wall 21 at the time of pressurization.

Many modiiications of the above invention may be used and it is not intended to hereby limit it to the particular embodiments shown or described. For example, the valve of this invention could be utilized with a package -in which the propellant is separated from the product by means of a flexible diaphragm such as is shown in U.S. Letters Patent 2,953,304, granted on September 20, 1960 The terms used in describing the invention are used in their descriptive sense and not as terms of limitation, it being intended that all equivalents thereof be included Within the scope of the appended claims.

What is claimed is:

l. A valve for admitting propellant to a container, comprising a piece of flexible, elastically distensible and substantially gas and liquid impermeable lm coated on one entire side with a co-extensive layer of pressure sensitive adhesive and a wall of said container having a permanently formed depression therein, said film overlying said depression in the internal surface of said wall of said container and attached by means of said pressure sensitive adhesive to a continuous area of said internal surface of said one wall surrounding said depression whereby in the unpressurized state said iilrn does not contact the surface of said depression and said adhesive coating is separated therefrom, and an aperture in the depressed portion of said internal surface providing communication from said depression through said one wall to the exterior of said container.

2. The valve claimed in claim l in which said depression is shaped substantially similar to the surface of a zone of a spherical segment of one base.

3. The valve claimed in claim 1 in which said depression has a depression ratio smaller than 1/4 and a depth of at least .003.

4. A pressurized dispensing container comprising a container body having a dispensing outlet valve at one end and a bottom wall at the other end, a floating piston intermediate the dispensing valve and bottom wall, said floating piston dividing the container into an upper charnber containing a product to be dispensed and a lower chamber containing a propellant, a permanently formed depression in said bottom wall, the depressed portion of said bottom wall having an aperture therethrough for charging the lower chamber with the propellant and a valve comprising a flexible, elastically distensible and substantially gas and liquid impermeable lm coated on one entire side with a layer of pressure-sensitive adhesive, said film covering the depression on the inside of the lower chamber and adhesively united to a continuous area of said bottom wall surrounding said depression whereby in the unpressurized state said film does not contact the surface of said depression and said adhesive coating is separated therefrom, said film being adapted to prevent outflow of the propellant following charging.

5. In a piston-type pressurized product dispensing container, a valve comprising a flexible, elastically distensible and substantially gas and liquid impermeable film coated 0n one entire side with a coeXtensive layer of pressure sensitive adhesive and a bottom wall of said container having a permanently formed depression therein, said lilm overlying said depression and attached by means of lsaid pressure sensitive adhesive to a continuous area of the internal surface of said bottom Wallsurrounding said depression whereby in the unpressurized state said lm does not contact the surface of said depression and said adhesive coating is separated therefrom, and an aperture through the depressed portion of said wall.

6. A pressurized dispensing container comprising a container body having a 'dispensing outlet valve at one end and a bottom Wall at the other end, a separating means intermediate the dispensing valve and bottom wall, said separating meansbeing adapted to divide the container into an upper chamber containing a product to be dispensed and a lower chamber containing a propellant, one Wall of said container also acting as a Wall of said lower Ychamber and having formed therein a permanently formed `depression with an aperture therethrough, and a valve tially gas and liquid impermeable film `coated on one entire side With a layer of pressure sensitive adhesive, said lm overlying said depression and adhesively united to a continuous area of the internal surface of said one Wall surrounding said depression whereby in the unpressurized state said lm does not Contact the surface oi' said depression and said adhesive coating is separated therefrom.

References Cited by the Examiner UNTED STATES PATENTS LOUIS I. DEMBO, Primary Examiner.

LEVERNE D. GEIGER, EUGENE F. BLANCHARD,

Examiners.

Claims

1. A VALVE FOR ADMITTING PROPELLANT TO A CONTAINER, COMPRISING A PIECE OF FLEXIBLE, ELASTICALLY DISTENSIBLE AND SUBSTANTIALLY GAS AND LIQUID IMPERMEABLE FILM COATED ON ONE ENTIRE SIDE WITH A CO-EXTENSIVE LAYER OF PRESSURE SENSITIVE ADHESIVE AND A WALL OF SAID CONTAINER HAVING A PERMANENTLY FORMED DEPRESSION THEREIN, SAID FILM OVERLYING SAID DEPRESSION IN THE INTERNAL SURFACE OF SAID WALL OF SAID CONTAINER AND ATTACHED BY MEANS OF SAID PURESSURE SENSITIVE ADHESIVE TO A CONTINUOUS AREA OF SAID INTERNAL SURFACE OF SAID ONE WALL SURROUNDING SAID DEPRESSION WHEREBY IN THE UNPRESSURIZED STATE SAID FILM DOES NOT CONTACT THE SURFACE OF SAID DEPRESSION AND SAID ADHESIVE COATING IS SEPARATED THEREFROM, AND AN APERTURE IN THE DEPRESSED PORTION OF SAID INTERNAL SURFACE PROVIDING COMMUNICATION FROM SAID DEPRESSION THROUGH SAID ONE WALL TO THE EXTERIOR OF SAID CONTAINER.