US 3022923 A
Description (OCR text may contain errors)
Feb. 27, 1962 H. T. HOFFMAN, JR
DISPENSING CONTAINER FOR VISCOUS PRODUCTS Filed March 2l, 1958 l C O Q5' Z5 IHHHIm BY MQW ilnited States Patent 3,022,923 DISPENSENG CONTAINER FR VISCGUS PRODUCTS Henry T. Hoffman, Jr., Barrington, Ill., assignor to American Can Company, New York, N.Y., a corporation of New Jersey Filed Mar. 21, 1958, Ser. No. 722,973 6 Claims. (Cl. 222-387) The present invention pertains to a can specially constructed to contain a viscous product and dispense this product by means of gas pressure within the can. More particularly, it pertains to a so-called pressure can having a novel construction whereby a viscous product and a pressure producing gas are contained and maintained in separate chambers within the can.
By the term pressure can as used herein is meant an hermetically sealed metal container having inside a product maintained under superatmospheric pressure by means of a gaseous propellant, and having a dispensing valve attached thereto whereby, upon opening of the valve, the product is ejected from the container by virtue of the pressure exerted thereon.
In general, the product-propellant system in pressure cans falls into either one of two categories. Either the product and propellant are mixed forming a homogeneous mass or solution; or the product and propellant are maintained separate. ln the rst category, the product, upon being dispensed, emerges as a spray, mist or foam depending upon, among other things, the characteristics of the product and propellant such as viscosity, surface tension, etc. In the class of spray or mist products are the well-known insecticide sprays and hair sprays. Examples of foam products are pressure dispensed whipped cream and instant lather shaving soap,
The present invention deals with the product-propellant systems belonging to the second category, i.e. wherein the product and propellant are maintained separate. This separation of product and propellant may be accomplished either by placingr a gas-tight, but movable barrier between the product and propellant, in which case the relative solubility characteristics of the product and propellant are immaterial; or a mutually insoluble product and propellant may be used in full or partial contact with each other.
lt is obvious that for viscous products which must be dispensed in their natural form or state, i.e. not as a foam, the product and propellant must be maintained separate. Products falling into this class are tooth paste, mayonnaise, mustard, ketchup, hand lotion, etc. Further, since these products primarily are for use in the home by persons o-f all ages, and thereafter discarded, it is equally obvious that the container in which they are sold and from which they are dispensed must be at least safe, easy to use, and relatively simple and inexpensive to manufacture.
Pressure cans having a gas-tight barrier between the product and propellant are disclosed in the prior art. This barrier either takes the form of a closed, flexible chamber, e.g. a plastic or rubber bag, within the can; or a movable piston in gas-tight engagement with the side wall of the can. Pressure cans of this type are diflcult and expensive to manufacture. Further, the friction resulting from the gas-tight seal between the piston and container wall necessitates relatively high pressures to move the piston and/or slow operation thereof. Also, the safety of such high pressure containers for general home use is questionable.
Before the instant invention, the prior art has never utilized to its fullest advantage the principle of mutual insolubility as a means of maintaining separation between product and propellant, at least not in a pressure can for general home use. The principal reason for this is that, because of their substantial diiferences in density, the propellant gas ordinarily overlies the product. Therefore, the product either must be dispensed from the bottom of the container which is cumbersome and annoying; or the container must be equipped with a dredge system whereby the product is forced from the bottom of the can up through a tube connected to a dispensing nozzle at the top of the can. With both of these constructions, there is a good possibility that the container will be tipped or tilted during use thereby permitting all or at least a portion of the propellant to escape. The care that must be exercised by the user to prevent this is annoying. Further, aside fro-m the fact that the dredge system can is relatively expensive to manufacture, in order for a viscous product to be readily forced through the dredge tube and dispensed, the viscosity of the product must be reduced usually causing the product to appear watery and unappealing.
It is therefore an object of the present invention to provide a pressure can containing a mutually insoluble, viscous product and gaseous propellant wherein the product is mantained above the propellant.
It is a further object to provide a pressure can of the type described from which a viscous product can be dispensed at a desired relatively high viscosity from a valve at the top of the can.
Still another object is to provide a pressure can of the type described for containing and dispensing a viscous product to be taken by mouth by humans and having no undesirable oif-llavors, adulterants or consistency.
Yet another object is to provide a pressure can of the character described which can be held in any desired position during dispensing of the product therefrom.
Another object is to provide a pressure can from which substantially all of the product may be dispensed with little or no possibility of propellant loss during the dispensing.
Yet a further object is to provide a disposable pressure can which is safe, easy to use, relatively simple and inexpensive to manufacture and highly suitable for use in the home by persons of all ages.
Numerous other objects and advantages of the invention will be apparent as it is better understood from the following description, which, taken in connection with the accompanying drawing, discloses a preferred embodiment thereof.
The pressure can construction of the instant invention by which the above objects are achieved comprises a tubular can body closed at each end and having therewithin a loose-fitting piston. A dispensing valve is mounted in the upper end closure; and the lower end closure has a scalable gas port therein for charging the can with a gaseous propellant. The upper portion of the can above the piston holds the viscous product t0 be dispensed; while the lower portion of the can below the piston holds the gaseous propellant which is an inert gas, insoluble in the product.
Referring to the drawing:
The single FIGURE is a side elevational view partially in section with parts broken away to show the interior of the can.
As a preferred or exemplary embodiment of the instant invention, the drawing shows a pressure can generally designated 10 having a sheet metal tubular body 11 to which are attached an upper and lower end closure 12 and 13 respectively joined to the body in a conventional double seam. Mounted in the center of the top end closure 12 is a -dispensing valve generally designated 14. This dispensing valve forms no part of the instant invention and is fully described in United States Patent No. 2,704,621. used, if desired.
In brief, the particular dispensing valve illustrated comprises a nozzle 16 extending upwardly from the end 12 and threaded as at 17 to hold a closure cap (not shown) over the nozzle to protect against accidental product discharge when the cans are not in use. At the base of the nozzle 16 is a compression spring 13 disposed between a collar 19 on the nozzle and the end closure i2 whereby the nozzle is resiliently maintained in an upright position with the valve ports closed. On the under side of end closure 12 and extending into the interior of the can is the base 20 of the valve 14 containing the normally closed ports but which upon tilting of nozzle 16 are opened to permit dispensing of a product 21 from the can 10.
The bottom end closure 13 has a hole or orifice 22 in the center thereof through which the gaseous prop'ellant 23, more fully described hereinafter, may be charged into the can. Port 22 may be sealed after the propellant gas has been charged by any suitable means such as the :rubber plug 24 shown in the drawing. It is to be understood that other means of charging propellant gas and sealing it within the container may be used such as a rubber plug having a self-sealing oritice through the center thereof through which a gas charging needle may be inserted.
Freely or floatingly mounted within the can body 11 is a piston generally designated 25. Piston 25 is composed of a I.relatively exible material essentially inert to Other suitable valves could be the action of chemical substances, polyethylene beingVV preferred. Piston 25 is cup shaped having a closed end 27 and is mounted within body 10 in an inverted position, i.e. with end 27 uppermost. Depending from piston end 27 is a side wall or skirt 28 connected to the end 27 through an arcuate or curved wall portion 29. The skirt 28 is substantially parallel to the side wall of the can body 11 and is slightly spaced therefrom when in an unstressed relaxed condition. For best operation of the can, itis preferred that the outside diameter of the piston 25 be about from 0.010 to 0.030 inch smaller than the inside diameter of the can body 11.
The cup shape of piston 25 traps a portion of the propellant gas 23 within its contines thereby transmitting the force exerted by the gas to the inside surfaces of the piston. This transmitted force not only tends to lift the piston, but also aids in forming a seal `between the product and propellant side of the piston. The cup shape of the piston also prevents cooking and' resultant jamming of the piston within the can. The center of the closed end 27 of piston 25 has a depression or debossment 33 the purpose of which will be described more fully hereinafter.
In the usual course of filling and charging the container 10, the product 21 is rst filled into the upper portion ofthe can whereby piston 25 is forced to its lowest position adjacent the bottom end 13. Due to the loose tit of piston 25 in can body 11, a thin lm of the product extends at least part way down between the skirt' 2S and adjacent portion of the can body side wall. Thereafter, the propellant gas 23 is charged through orifice 22 into the space below piston 25. The pressure exerted by gas 23 on the piston 25, in addition to the vertically upward force exerted on the piston end 27,
forces the flexible skirt 2S radially outwardly against the contiguous lilm of the product 21. Initially when the product is rst filled into the container, the film of product does not extend downwardly very far between the can body side wall and the skirt 23 because of the narrow contines of the space between these members. However. due to the curvature of the surface 29, the piston 25 does not scrape clean the side wall of the body 11 as it rises; and, therefore, aside from this initial situation, a film of product is maintained completely between skirt 23 and the can body side wall throughout tbe. entire'. useful-life of the can as the piston` travels-upwardly since a new film of product is continually provided between the can body wall and skirt 28.
As mentioned previously to be operable the propellant gas of the instant invention must be insoluble in the product 21 and also it must be completely inert so aS to produce no odor, taste or corrosion problems in the container. The gas most suitably meeting these requirements is nitrogen. However, other inert gases such as argon and helium could be used, although their expense makes them less desirable. Propellant gases conventionally used in pressure cans such as Freon, CO2, nitrous oxide and air are unsuitable in the container of the instant invention, since all of these gases are at least partially soluble in the products which the subject can is specifically designated to hold. The primary disadvantage of air, is the 21% content of oxygen thereof which oxygen is relatively soluble in the products and also creates problems of corrosion and product deterioration.
The film of product between the skirt 28 and the can body acts as a resilient sealing gasket whereby any irregularities in the can body, such as dents, variations from the tubular, or the side seam of the can are nullied as potential leak passages from the propellant side of the piston to the product side of the piston. The iilm of product also acts as a lubricant permitting easy movement' of the piston. It is readily apparent that if the propellant gas had any solubility effect on the product, this film, which is in contact with the gas, would be removed. Also, because of the combined etfects of viscosity of the product tending to resist ow thereof and the mutual insolubility of product and propellant whereby the gas 23 presses against the film without diffusing into or through the film, the product 21 exhibits no tendency to low around the piston down into the propellant compartment.
When piston 25 reaches its uppermost position as shown in dot dash lines in the drawing, its top 27 conforms closely to the inside surface of the can end 12 and the depression 30 encloses the base 20 of valve 14 sealingoff theV valve from the interior of the container. The purpose of this construction is to force substantially all of the product from the can and prevent escape of the propellant gas after electively all of the product has been dispensed. The gas escaping after the can is substantially empty carries bits and droplets of entrained product which emerge from the dispensing nozzle in the form of untidy, if not messy sputterings.
From the foregoingY disclosure, it can be seen that the container of the instant invention permits the maintenance of a viscous product under superatmospheric pressure in the upper portion of a pressure can in direct contact with the dispensing valve, with the pressure producing propellant gas maintained below and separate from the product, but in partial contact with the product. With such an arrangement, products of any desired highl viscosity may be dispensed; and the product may be dispensed from the container without danger of propellant loss although the container is held in any position, even inverted. Further, the simple arrangement of parts requiring no gas-tight seal between the piston and container wall are obviously inexpensive to manufacture and assemble; and since no excessively high pressures are needed, the container is safe and easy to use by persons of all ages. The use of the inert, insoluble, non-toxic propeliant gas, preferably nitrogen, maxes the subject container highiy suitable for the dispensing of viscous food products and in general viscous products to be taken orally by humans.
it is thought that the inventionl andmany of its attendant advantages will be understood from the foregoingV description, and it will be apparent that various changes may be made in the form, construction and arrangement of the parts without departing from the spirit and scope of the inventionl or sacriticing all of its material advantages, the form hereinbefore described being merely a preferred embodiment thereof.
1. A pressure can comprising a tubular metal body having upper and lower end closures integral therewith, the upper one of said closures having a dispensing valve mounted therein, and an imperforate cup shaped piston mounted in inverted position within said body, said piston having only a closed end facing toward said valve and a substantially straight skirt depending from said closed end and disposed contiguous the side Wall of said body, said piston dividing the interior of said body into an upper viscous product chamber communicating with said dispensing valve and a lower propellant chamber, said propellant chamber adapted to contain a gaseous pressure producing propellant insoluble in said viscous product in said product chamber which maintains a continuing pressure on said piston to force said piston upwardly toward said valve upon actuation of said valve to dispense said product, said closed end being out of contact with said body side wall and the entire length of said skirt having a .transverse cross-sectional shape and transverse exterior size the same as and smaller than the transverse cross-sectional shape and transverse interior size of said body respectively to provide a loose t between said piston and said body side wall to permit the formation of a `thin film of said product between said skirt and said body side wall, said lilm of product being both a sealant to prevent escape of said propellant around said piston and into said product and a lubricant to facilitate upward movement of said piston upon valve actuation.
2. A package comprising a container, a viscous product in the upper portion of said container, and a gaseous propellant insoluble in said product in the lower portion of said container; said container comprising a tubular metal body having an upper and lower end closure integral therewith, a dispensing valve in said upper closure in contact with said product, and an imperforate cup shaped piston mounted in inverted position within said body; said piston having only a closed end facing toward said valve and a substantially straight skirt depending from said closed end and disposed contiguous the side wall of said body, said piston separating said propellant from the bulk of said product, said closed end being out of contact with said body side wall and the entire length of said skirt having a transverse cross-sectional shape and transverse exterior size the same as and smaller than the transverse cross-sectional shape and transverse interior size of said body respectively to provide a space between said skirt and said body side wall, a thin film of said product filling said space, said lm being both a sealant to prevent escape of said propellant around said piston and into said product and a lubricant to facilitate upward movement of said piston upon valve actuation, said propellant exerting a continuing pressure on said piston to force said piston upwardly toward said valve upon actuation of said valve to dispense said product.
3. The pressure can set forth in claim 1 wherein said cross sectional shape of said body and said piston is circular.
4. The pressure can set forth in claim l wherein said piston is composed of polyethylene.
5. The package set forth in claim 2 wherein the propellant is selected from the group consisting of nitrogen, argon and helium.
6. The package set forth in claim 2 wherein said viscous product is tooth paste and said gaseous propellant is nitrogen.
References Cited in the le of this patent UNITED STATES PATENTS 1,934,225 Candor Nov. 7, 1933 2,459,743 Trainer et al. Jan. 18, 1949 2,604,230 Payne July 22, 1952 2,661,126 Spencer Dec. 1, 1953 2,723,200 Pyenson Nov. 8, 1955 2,806,238 Wisey Sept. 17, 1957 2,809,774 Kaye et al. Oct. 15, 1957 2,895,650 Mahon et al. July 21, 1959 2,907,358 Armstrong Oct. 6, 1959