US3122284A - Pressurized dispenser with pressure supplying and maintaining means - Google Patents

Description

Feb. 25, 1964 G. DE WAYNE MILES 3,122,284 PRESSURIZED DISPENSER WITH PRESSURE SUPPLYING AND MAINTAINING MEANS Filed June 6, 1960 INVENTOR GILBERT DEWAYNE MILES E ATTORNEY United States Patent 3,122,284 PRESSURIZED DISFENSER WITH RESURE SUPELYENG AND MAlNTAlNlNG NEAN Gilbert De Wayne Miles, @ssining, N.Y., assignor to (irrigate-Palmolive (Zompany, New York, N.Y., a corporation of Delaware Filed June 6, 196b, Ser. No. 33,992 5 Claims. (Cl. 222-3559) This invention relates to a pressurized dispensing container of shatterable material which has been made safer for use by the confinement of a proportion of propellant in a body within the container.

Self-dispensing pressurized containers for aeroso products are usually manufactured by rolling metallic sheet, such as black iron, tin plate or aluminum or by drawing containers from slugs of these or other suitable metals. Because many procucts being dispensed, e.g., aqueous solutions and emulsions, and propellants and solvents used with them react with metals, protective coatings are usually applied to prevent corrosion of the container. Such corrosion, if not prevented, can result either in leakage or in production of particulate reaction products which obstruct the relatively small openings in the discharge valves employed. Although the additional operation of applying a coating to the inte rior container walls may be effective to prevent objectionable corrosion, there are some products which are incompatible with the coatings available or which penetrate through microscopic perforations therein. Due to their reactivity, such products cannot be commercially marketed in metal containers. However, these and many other materials, it has been found, are easily dispensable from glass containers without the disadvantages associated with metals and other of the more reactive container materials.

Glass bottles have een employed for a long time as containers for pressurized fluids, e.g., carbonated beverages. Although the internal pressure in such bottles has very occasionally caused what may be described as minor explosions, when the bottle was broken, as a rule, with such products the release of pressure does not propel harmful fragments for any appreciable distance and the effect of breakage is rarely much ditierent from that resulting from merely dropping a bottle which is not under pressure. The relatively minor eifect of breakage or" bottles containing carbonated water is apparently attributable in large part to the comparatively small proportion of gas volume present as well as the greater solubility of carbon dioxide in the fluid product and the generally lower pressures employed. However, the higher pressure aerosol products packed in glass are at comparatively high pressures and contain proportionately large gas volumes (especially after partial consumption of contents), l ading to the danger or" explosive shattering of the container it it is accidentally broken or cracked.

Attempts have been made to overcome the danger of breakage and shattering of glass aerosol containers by covering them or coating the glass bottles used with a plastic capable of preventing flying glass by substantially maintaining its own shape and adhering to the glass particles after breakage, despite the rapid release of container pressure. In some products vents have bee included in the plastic coating to allow rapid dissipation of the confined propellant vapor, preventing distention, ballooning and breaking of the plastic. Plastic coatings have een successfully employed, usually with higher priced products, such as cosmetics and colognes, where the cost of coating is not economically intolerable. With strongly competitive products the additional expense of coating often is a disadvantage that prevents successful marketing of the product. Also, plastic coatings cannot Patented be printed or lithographed as well as glass or metal and often require a special label sleeve or package to carry essential label information.

From the above review of the status of pressurized protected glass containers, it will be realized that the discovery of a means of producing a safe pressurized glass dispenser, without necessitating coating, covering or otner costly external modifications of the container, would be highly advantageous and would allow the manufacture of glass aerosol dispensers for virtually a host of pressurized products. The present invention is of such an improvement and is directed to the production of safer packages for dispensing pressurized products.

In accordance with this invention a pressurized dispenser of reduced tendency to explode, when accidentally dropped, comprises a container made of shatterable material, fluid contents to be dispensed, propellant fluid, a normally closed discharge outlet and a foamed synthetic organic plastic inside the container and in contact with the propellant which absorbs propellant fluid under pressure and releasably confines it within voids in the foam, diminishing explosive expansion of the propellant and helping to prevent dmgerous shattering of the container when container pressure is suddenly decreased, due to accidental breaking of the container wall, while enabling the propellant to expand to assist in discharging fiuid contents when the pressure in the container is decreased, due to opening or" the normally closed discharge outlet.

Al hough the invention may find application to the making of pressurized packages comprising liquefied gases it is primarily intended to serve to restrict and regulate the release of pressure of a propellant in the gaseous state, decreasing the shock of pressure release and cushioning it so that the shatterable container walls will not be sent flying dangerously about when accidentally cracked by a sudden shock or blow.

A preferred form of the invention for such application is a pressurized dispenser comprising a glass container, fluid contents to be dispensed, propellant gas in separate phase from the dispensable contents, a normally closed discharge valve and a foamed synthetic organic plastic containing a multiplicity of small non-communicating cells, the foamed plastic being inside the container and in contact w th the propellant gas, the plastic being impermeable to dispensable contents and permeable to the propellant gas so that, when in such gas under pressure, the propellant will be transmitted through the plastic into the individual small cellular compartments of the foam, thereby becoming "eleasably confined within those cells and helping to prevent explosive expansion of the propellant and dangerous shattering of the glass when contm'ner pressure is suddenly decreased, due to accidental breaking of the container Wall, while being gradually releasable from the cells and restoring discharging pressure on the fluid contents after the pressure in the container is decreased, due to open .g of the normally closed discharge valve.

The invention and objects thereof will be readily understood from the following description, taken in conjunction with the accompanying drawings in which:

FIG. 1 is a side elevation of a transparent dispensing container;

FIG. 2 is a disassembled view of the parts of such a dispensing container in half sectioned elevation;

FIG. 3 is a top plan of the dispenser; and

FIG. 4 is a partial central vertical sectional view of another form of the foamed body of synthetic organic plastic in a dispensing container.

Numeral 11 designates a container of shatterable material, such as glass which, when broken while under internal pressure of propellant, will crack and shatter into a multiplicity of sharp-edged pieces which can be violentamazes U 1y hurled about by the force of the escaping propellant gas so as to constitute a hazard to persons in the vicinity. Such a container is usually molded of glass but containers made of brittle plastics such as phenol formaldehyde, melamine formaldehyde, epoxy resin, cellulose acetate butyrate, polystyrene, and nylon, may also be benefited by the present invention. Metallic containers, as a rule are not shatterable, although they may be severely distorted by rupturing of the container wall, accompanied by forceful escape of contents.

Glass container 11 comprises a cylindrical side wall 13, bottom 15 and rounded top or shoulder 17 which is adapted for insertion of a discharge valve or valve iitment in opening 19 of neck 29. Valve 21 comprises a body 23 in which is housed spring 25 which holds valve stem 27 upward in position where gasket 29 is pressed against outlets 31 preventing escape of contents 33. Upon depression of actuator 35 valve stem 27 is moved downwardly so that dispensable fluid is conveyed through openings 3d and out of the container through stem 2'7 and spout 37. At the bottom of the valve is an extension or spigot 39 on which is placed a dip tube 41. About the neck 2 of container 11 there is swaged and crimped a valve fitment which is applied after filling of the contents 33 and, with adapter and gasket 45, holds the valve in pressure tight closed relationship with the container.

The valve parts may be made of materials of construction suited for exposure to the products being dispensed and the propellants employed. It is preferred to make the gaskets of Neoprene or other substantially non-swelling rubber or plastic, the valve body and stem of nylon or equivalent dimensionally stable non-reactive plastic, the dip tube of polyethylene and other internal parts of suitable plastics. The spring is usually of stainless steel. The valve actuator and spout may be made of any of a number of suitable materials, plastics being highly preferable, and polyethylenes being the most satisfactory and economical materials at present.

Inside the container, at the bottom thereof so 'as to communicate with the dip tube opening, are fluid contents 33. The fluid being dispensed may be a thin liquid, a viscous gel or paste or even a freeflowing powder of sufiiciently small particle size so as to clear the discharge valve passageways. Among the many materials that may be dispensed from such a package are room odorants, dental creams, shaving creams, insecticides, cosmetic lotions, hair sprays, shoe polishes, waxes, cleansers and medicinals. When dental creams, cosmetic lotions or other of the less free-flowing fluids are dispensed, the dip tubes and valve passages should be sufliciently large to permit satisfactory flow rates. For such products the tube diameter and valve orifices should be larger than for conventional spray products.

Above the dispensable contents is the volume normally occupied by propellant gas under pressure, the propellant serving to force the contents out of the container when the discharge valve is actuated. Various suitable gases may be employed for this purpose but experience has indicated that nitrogen is generally the most advantageous, being comparatively inert, inexpensive and generally insoluble in the pressurized compositions. Oxygen, the lower hydrocarbons, halogenated lower hydrocarbons, e.g., the well known fluorochlorinated lower hydrocarbons, may be used with compatible compositions and suitable foamed synthetic organic plastics.

The dispensing container described above is one which will violently shatter if dropped with sufiicient force to crack the glass or other brittle material of construction employed. The internal gas pressure, usually of 26400 pounds per square inch, is sufficiently high to cause the fragments of container Wall to be forcefully hurled for substantial distances. The presence in the container of a foamed plastic body of the type herein described helps decrease the force of such an explosion, due to a confining action exerted by the foam on propellant gas, slowing down its escape and diminishing the effective force of the propellant pressure at the time of breakage of the container. A body of foamed synthetic organic plastic 4-5 floats on contents 33. Being lighter than the contents, it does not project downwardly into the body of dispensable material so as to interfere with the flow of such material to the dip tube. As illustrated, the dip tube passes through a passage 54} in the foamed body. Foam 45 is made up of a multiplicity of very fine thin-walled closed cells 48. The cell wall thickness should usually be between about 0.001 and 0.005 inch and the diameters of the non-communicating cells should be between about 0.01 and 0.2 inch. If cell walls are too thin, the foam will tend to be too easily ruptured by a rapid pressure change and, if of very resilient material, might prove too flaccid to be of useful confining properties. If too thick, the foam wall will not allow the transmission through it of pressurizing gas. Cells which are below .01 inch in diameter often require cell walls which occupy a substantial proportion of the volume and limit gas holding elliciency. Cells larger than .2 inch may often have comparatively little confining effect on gaseous propellant, unless the cell walls are strong, as well as being sufficiently permeable to gas. Of course, depending on the plastic used and the conditions of dispensing, the dimensions of the foam cells and cell walls may be modified somewhat from these ranges, but usually such action is accompanied by a loss in desired performance and effect.

The foam plastic may be of any desirable shape. It is preferable to employ a resilient material which may be readily inserted through the comparatively narrow neck opening of the pressurized glass dispensers commonly employed but non-resilient foams may also find use. Either one piece of foam material 45 or several pieces 52 may perform the fluid confining function, the latter embodiment facilitating placement in a container 54 with a narrow neck, 56. If desired, the foams may be attractively colored and shaped for use with transparent glass containers or, alternatively, the container may be opaque so as to conceal the presence of foam.

The synthetic organic plastic material from which the foamed body is made may be any suitable plastic which is not seriously adversely affected by the other contents of the pressurized dispensing container. The plastic should be chosen to be compatible with the composition being dispensed and should not be dissolved by that composition nor should it have its properties objectionably modified by leaching of plasticizer. ploy the resilient organic materials such as poly lower alkylene plastics, e.g. polyethylene, polyvinyl derivatives, such as polyvinyl chloride, and polyurethanes but polystyrenes, nylons, cellulosic derivatives, such as cellulose acetate and other more rigid plastics may be useful, too. Neoprenes and other rubber-like elastomers are satisfactory in compatible systems. The resilient plastics are preferred, in part, because the separate cells are not unduly strained upon initial pressurizing of the container and do not tend to rupture due to an unbalance of internal and external pressures. They are also easier to insert in many containers and conform better with the container shape. When of original size equal to that of the container volume, resilient plastics of good elastic memory (those which do not take a permanent set when distorted) may be compressed when placed in the dispenser and will subsequently gradually expand to fill a substantial part of the container volume which is vacated when material is dispensed. Thus, there will be less free gas space in the container, more confined gas and a reduc.ion of the explosion hazard. Resilient foams also respond rapidly to decreases of container pressure, expanding almost instantly to take the place of dispensed contents. Thus dispensing pressure is held constant.

The main requirements of the plastic sponges or foams used are that (l) propellant may pass into and out of the it is preferred to em.

b foam slowly but suf iciently fast to maintain product pressure during normal use and (2) the foam should exert a confining action on the propellant, restricting its release.

The plastic used should have cells of a wall thickness which results in a transmission rate of propellant passing into the cell interiors which is a slow but practicable one. Thus, perforated cells, or communicating passageways which would allow propellant (and sometimes product, too) to penetrate the foam without appreciable resistance, would be of a more limited utility in temporarily confining the explosive effect of the gas. On the other hand, wall thicknesses or designs which prevent any gas transmission or so slow the rate of transmission that the propellant cannot pass from the cell interiors to the free volume in the container above the dispensable product sufliciently quickly, would not be useful because frequent utilization of the dispenser would result in a deficiency of pressure to assist the discharge. The gas permeabilities for various plastics vary, as do the moisture absorptions and liquid transmissions of such materials. As a rule their permeability to gases is much higher than to liquids and therefore it is relatively easy for one of skill in the art to select plastic foams which will suitably allow gas transmission while preventing entrance of liquids and other fluids into the cell interiors. It is usually desirable to utilize foams into which the product cannot penetrate so that there is no loss of dispensable material due to physical entrapment in the foam cells.

To have a confinin effect, the foam, if of resilient material, should tend to return to its normal shape, even after partial collapse due to pressurizing. A foam which has no such tendency will not absorb propellant gas, even though it is permeable, because the internal and external gas pressures will be equalized during compression, leaving no driving force to cause enlargement of the foam to suit it for use as a confinement for the propellant. Rigid foams hold their desired shape, despite pressur zing and the unbalance of internal and external pressures. To prevent collapse and quick destruction of the foam during pressurizing or quick release of pressure, cells should be small and walls should be of thickness and strength to withstand the expected forces.

The manufacture of a dispensing container in accordance with this invention may be conducted in substantially the same manner as for ordinary glass pressurized dispensers. The glass bottle is filled with the requisite amount of product, the cellular plastic foam is inserted, the valve assembly with attached dip tube is positioned and sealed in place and the container is pressurized by addition of propellant gas through the valve opening. During pressurization, the volume of resilient foam decreases because of the unbalance of external and internal gas pressure. The container is then tested for leakage, correct weight and pressure, and after passing these inspections, tie dispensing spout unit is installed. After placement of protective caps and labelling (if the container has not previously been lithographed) the dispensing containers are packed and shipped. During these operations and also during storage before shipment the gaseous propellant in the container external to the foam cells continues to diffuse into those cell being driven by the pressure differential. When the pressures are equalized the foam has returned substantially to its original size and the safety feature of the product is operative.

Glass pressurized packages have been made at the direction of the present inventor and have been tested to determine whether the explosive force of the propellant was materially reduced. Polyethyl ne foam, of the type previously described, in which the individual cells were non-communicating, was cut to a size which could be inserted in a glass container and then the container was assembled and sealed according to the method previously described. After the pressurized gas had permeated the cell walls the package was intentionally dropped to cause breakage. A control dispenser having no foamed plastic present was tested in similar fashion. While the dispenser made according to this invention did break and cause some propulsion of glass fragments, the driving force was obviously much diminished over the control and the area over which fragments were scattered was appreciably less. These comparisons were repeated and the results have been undeniably confirmed.

It will be evident to those of skill in the art that Various equivalents may be substituted for elements of the claimed structure without departing from the invention or transcending the scope of the claims. Then too, modifications of the invention less advantageous than the preferred embodiment described may be found of some use in certain applications. Thus, instead of using a dip tube which would facilitate top dispensing of the product the container may be kept inverted to dispense from the bottom only. Although not essential, an additional safety feature may be built into the dispenser by the use of an external plastic coating on the container. A single phase propellant-product system may be used instead of the Z- hase-gas-luid system described. In such a system liquefied gas propellant and plastic could be so chosen as to allow penetration of the propellant into the foam cells. To utilize plastics of low gas transmission characteristics, minute openings or breaks could be made in the cell walls to facilitate penetration of gas, while still restricting the passage of liquid contents. Other modifications of the invention will occur to those of skill and experience in t ie pressure dispensing art from a reading of the foregoing specification.

W hat is claimed is:

1. A pressurized dispenser comprising a glass container, fluid contents to be dispensed, propellant gas in separate phase from the dispensable contents, a normally closed discharge valve and foamed synthetic gas-permeable organic plastic containing a multiplicity of small non-communicating cells, the foamed plastic being inside the container and in contact with the propellant gas, the plastic being impermeable to dispensable contents and permeable to the propellant gas so that, when in such gas under pressure, the propellant will be transmitted through the plastic into the individual small cellular compartments of the foam, thereby becoming releasably confined within those cells and helping to prevent explosive expansion of the propellant and dangerous shattering of the glass when container pressure is suddenly decreased, due to accidental breaking of the container wall, while being gradually releasable from the cells and restoring discharging pressure on the fluid contents after the pressure in the container is decreased, due to opening of the normally closed discharge valve.

2. A pressurized dispenser comprising a glass container, a normally closed discharge valve, fluid contents to be dispensed, communicating with the discharge valve, propellant gas in separate phase from the dispensable contents and gas-permeable foamed synthetic organic plastic containing a multiplicity of small non-communicating cells of diameter between 0.01 and 0.2 inch and cell wall thickness between about 0.001 and 0.005 inch, the foamed plastic being inside the container and in contact with the propellant gas, the plastic being impermeable to dispensable contents and permeable to the propellant gas so that when such gas is under pressure it will be transmitted through the plastic into the individual cellular compartments of the foam, resulting in an equilibrium between the pressure in the foam cells and that of the dispensable contents, said equilibrium discharge pressure being from 28-100 pounds per square inch, the propellant gas thus being releasably confined within those cells and helping to prevent explosive expansion of the propellant and dangerous shattering of the glass when container pressure is suddenly decreased, due to accidental breaking a t the container wall, while being gradually released from the cells to restore discharging pressure on the fiuid contents and to equalize container and foam cell gas pressures after the pressure in the container is decreased, due

opening of the normally closed discharge valve.

3. A pressurized dispenser comprising a glass container, a normally closed manually actuatable discharge valve, fluid contents to be dispensed, communicating with the discharge valve, propellant gas in separate phase from the dispensable contents and gas-permeable resilient foamed synthetic organic plastic containing a multiplicity of small non-communicating cells of diameter between about 6.01 and 0.2 inch and cell Wall thickness between about 0.001 and 0.665 inch, the resilient foamed plastic being inside the container in contact wit 1 the propellant gas and, t the propellant gas, at an equilibrium pressure occup ing substantially all the initial free space in the container, the plastic being impermeable to dispensable contents and permeable to the propellant gas so that when such gas is under pressure it will be transmitted through the plastic into the individual c llular cornpartmerits of the foam resulting in an eq teen pressure in the foam cells and that of the dispensable contents, said pressure being from 2G-l00 pounds per square inch, the propellant gas thus being releasably con- Within those cells and helping to prevent explosive expansion of the propellant and the dangerous shattering of the glass when container pressure is suddenli decreased due to accidental breaking of the container .vail, While bein gradually released from the cells to restore discharging pressure on the fluid contents and to equalize container and foam cell gas pressures after the pressure in the container is decreased, due to opening of the norly closed discharge valve, the resilient foam plastic being capable of expanding sufficiently when the discharge valve opened, due to the internal pressure of the confin d gas, so that the desired pressure of the fiuid being discharged is maintained before equilibrium between foam cell gas pressure and contents pressure is established.

4. A pressurized dispenser according to claim 1 in the foamed s nlhetic or anic lastic is Dolveth- J v a .4

5. cssurized dispenser comprising a glass cond contents to be pensed, propellant gas in nase from the dispensable contents, a normally barge valve and carried resilient synthetic orplastic of good elastic memory containing a milltiplicity of small non-communicating cells, the foamed being in ide the container and in contact with the propellant gas, the plastic being imperi cable to dispensable cont and permeable to the propellant gas so that, len in such gas under pressure, the propellant will be tr .1 itted through the plastic into the individual small cellular compartments of the foam, thereby becoming relea" bly confined within those cells and helping to prevent c ve expansion of the propellant and dangerous shattering of the glass when container pressure is suddenly decreased, due to accidental ainer Wall, While being gradually releasable from the eils 'estoring discharging pressure on the fluid contents af er the pressure in the container is decreased, due to op ng of the normally closed discharge valve, and when internal container pressure is decreased due to disc ge of co ents upon actuation of the normally closed "large valve, the foamed plastic Will expand in volume equal to the volume of contents dispensed so as to fill substantially all the container interior not occupied by dispensable contents.

Reierenees Cited in the file of this patent UNITED ST TES PATENTS rcaking of the con-

Claims (1)

1. A PRESSURIZED DISPENSER COMPRISING A GLASS CONTAINER, FLUID CONTENTS TO BE DISPENSED, PROPELLANT GAS IN SEPARATE PHASE FROM THE DISPENSABLE CONTENTS, A NORMALLY CLOSED DISCHARGE VALVE AND FOAMED SYNTHETIC GAS-PERMEABLE ORGANIC PLASTIC CONTAINING A MULTIPLICITY OF SMALL NON-COMMUNICATING CELLS, THE FOAMED PLASTIC BEING INSIDE THE CONTAINER AND IN CONTACT WITH THE PROPELLANT GAS, THE PLASTIC BEING IMPERMEABLE TO DISPENSABLE CONTENTS AND PERMEABLE TO THE PROPELLANT GAS SO THAT, WHEN IN SUCH GAS UNDER PRESSURE, THE PROPELLANT WILL BE TRANSMITTED THROUGH THE PLASTIC INTO THE INDIVIDUAL SMALL CELLULAR COMPARTMENTS OF THE FOAM, THEREBY BECOMING RELEASABLY CONFINED WITHIN THOSE CELLS AND HELPING TO PREVENT EXPLOSIVE EXPANSION OF THE PROPELLANT AND DANGEROUS SHATTERING OF THE GLASS WHEN CONTAINER PRESSURE IS SUDDENLY DECREASED, DUE TO ACCIDENTAL BREAKING OF THE CONTAINER WALL, WHILE BEING GRADUALLY RELEASABLE FROM THE CELLS AND RESTORING DISCHARGING PRESSURE ON THE FLUID CONTENTS AFTER THE PRESSURE IN THE CONTAINER IS DECREASED, DUE TO OPENING OF THE NORMALLY CLOSED DISCHARGE VALVE.

Images