US2888789A - Method of filling volatile propellant on warm product - Google Patents

Description

RODUCT June 2, 1959 A. B. MOJONNIER METHOD OF FILLING VOLATILE PROPELLANT ON WARM P 17, 1958 Filed Feb.

2 Sheets-Sheet 1 June 2, 1959 A. B. MOJONNIER 2,888,789

LLANT ON WARM PRODUCT METHOD OF FILL ING VOLATILE PROPE Filed Feb. 17, 1958 2 Sheets-Sheet 2 I I ll and the like which include conditions.

r ,88 7 'METHOD OF FILLING VOLATILE PROPELLANT ON WARM PRODUCT Albert B. Mojonnier, Chicago, Ill., assignor to Karlridg- Pak Machine Co., Chicago, 11]., a corporation of Iowa Application February 17, 1958, Serial No. 715,615 7 Claims. cuss-25 invention relates to the packaging of aerosols a liquid product and a volatile propellant in a pressurized container.

At present, there are two general systems for packaging liquid products and volatile propellants, which systems are briefly referred to as the cold filling method and the pressure filling method. In the cold filling method, the filling is effected at atmospheric'pressure.

The liquid product is cooled to a low temperature and "the volatile propellant is sub-cooled to a temperature below its boiling point at atmospheric p'ressureandis dispensed under atmospheric pressure on top'of the cold product in the container. The valve is thereafter applied :to the container to sealthe same. The cold filling method Works well on those products which remain'a 'tfiowable liquid when cooled to a temperature at or near {the boiling point of the volatile propellant at atmospheric pressure since such products can be cooled prior to being dispensed into the container. However, the cold filling method does not work well on those products which even partially solidify at the temperature near the boiling point of the volatile propellant under atmospheric pressure Such products obviously cannot becooled prior to their introduction into the container. Although it has been proposed to cool these products afterthein introduction into the container by passing the containers through a refrigeration bath, this procedure is unsatisfac- 'tory because of the markedly increased time and machinery required for such a filling operation. Refrigeration of the containers requires a relatively large refrigerating bath and complex apparatus for passing the containers therethrough. In addition, considerable delay is incurred-in passing the containers through the'refrigeration bath after introduction of the product thereinto and in heating the filled containers after completion of the filling operation to liquify the products in the container. Moreover, when the valves applied to the containers are of-the type employing a syphon tube, difficulty is .encounteredin inserting the tube after the product in the container is solidified.

The pressure filling method is slow as compared to the cold filling method'and is used primarily for packaging those liquid products which are solid or'semi-solid at the boiling point of the propellant under atmospheric jpressure conditions and which cannot be filled by the conventional cold filling method. In the pressure filling method, the liquid products is dispensed into the container under atmospheric pressure and at room temperature and the dispensing valve then applied to the container to seal the same. Volatile propellant, at generally ambient temperature and under an elevated pressure sufficient to liquify the same at that temperature,is forced through the valve into the container. With this process, no chilling of the product occurs so that item be used for products which wouldsolidify if filled by the cold filled method. However,as previously noted, this method 'is relatively slow particularly when a large amount of propellant must be introduced into the container since the liquified propellant must all be'forced through the relatively restricted dispenser valve on the container.

'In pressure filling, an additional problem is presented due'to the necessity of removing the'air from "the contain'er'before sealing the same. The presence of air in the completed package is undesirable because of the finited States Patent product prior to the 2,888,789- Patented June 2, 1959 increase in vapor pressure which mixes with the volatile propellant. The containers employed in such pressurized packages are made of as light weight stock as will. safely withstand the vapor pressure of the propellant at a temperature somewhat above normal roomtemperature. If the vapor pressure of-the propellant is increased appreciably by the presence of air in the container, a dangerous condition may exist if such containers become heated. Moreover, with some products such as paint, the increased pressure is undesirable because of the change in spray pattern which accompanies the increased pressure in the container.

In the cold filling method, enough liquidjpropellant vaporizesbefore the dispensing valve is afiixed to the container to drive out the air in'the container. In the pressure filling method, however, special steps mustbe taken to remove the air. 'It has heretofore been proposed to evacuate the containers before clinching the valve in place. Howeverjthis' is not satisfactory since, at best, avacuum of-only about 22 inches of mercury can be commercially achieved in the containers and, with such a vacuum, approximately one-third of the air still remains 'in the container after evacuation. An alternative method for removing the air is known as purging. In this method, a small quantity of liquified propellant, generally one or two grams, isdispensed into the'container aftei the product has been introduced thereinto and allowed to completely vaporize to drive out the air in the container before-sealing the same. Thepresent purger's usually squirt the'liquid propellant under a relatively high pressure into the container, and some difliculty' has been encountered due tothe rather violent agitation and boiling of the propellant as it enters the warm product in the container. This agitation is requently so violent" as to cause splashing of some of the liquidproducts out of the container. While the one or two gram purge reduces the amount of air present in the final package, some air does in fact remain in the container resulting in anover pressure, that is a pressure above the vapor pressure of the propellant alone. "Moreover, attempts to reduce this overpressure, by increasing the amount of the purge, even up to five grams for a l2-ounce container, have not been successful.

An important object of this invention isto provide an improved method for rapidly packaging a volatile propellant and a liquid product which solidifies or thickens .at a temperature near the boiling point of the volatile propellant at atmospheric'pressure.

Another object of this invention is to provide an improved method for packaging a cold sensitive liquid product and a volatile propellant in a container which method does'not require chilling or refrigeration of the introduction of the propellant into the container and in which at least a portion of the pro pellant in the completed package is introduced thereinto under atmospheric pressure.

A further object of this invention is to provide an improved method for dispensing a liquified propellant on .top of a warm product in such a manner as to mini mize agitation of the product due to the heating and vaporization of the propellant upon contact with the warm product, and which produces a substantially complete purge of the air in the container.

A more particular object of this invention is to provide an improved method for packaging a liquified propellant and a product which is liquid at ambient temperature and which thickens or solidifies at the boiling point of the propellant under atmospheric pressure, in which the liquified propellant is introduced into the containerin such a manner as to chill orsolidify only the surface layer of the product to thereby minimize agitation: .of

occurs when the .air

connection with the accompanying drawings wherein:

Figure 1 is a diagrammatic plan view of an apparatus for practicing the method of the present invention; 7

Fig. 2 is a front elevational view of the apparatus illustrated in Figure l, w'th parts broken away and shown in section to illustrate details of construction; and

Fig. 3 is a front elevational view of a modified form of filler for dispensing liquid propellant into the container, and with parts broken away and shown in section to illustrate details of construction.

The method of the present invention is particularly adapted for packaging, in pressurized containers, those liquid products which are liquid at normal room or am bient temperature but which thicken or solidify at temperatures near the boiling point of the volatile propellant under atmospheric pressure conditions. At present, such products are commercially packaged by the pressure filling method since these products cannot be refrigerated prior to filling as is necessary in the present commercially practical cold filling methods. With the present method, the filling of the container with such products can be effected more rapidly than by the regular pressure filling method. in addition, the present method also effects substantially complete purging of air from the container without the violent agitation and splashing of the product normally incident to the purging operation.

Reference is now made more specifically to the apparatus diagrammatically illustrated in the accompanying drawings for practicing the method of the present invention. In accordance with this method, a measured quantity of a product, which, as previously described, is of the type which is a liquid at room temperature and which solidifies or thickens at lower temperatures near the boiling point of the propellant under atmospheric pressure conditions, is dispensed into a container C. The product, designated A, is maintained at substantially ambient or room temperature (generally about 70 F.) during the filling operation so that the product remains a readily flowable liquid and a measured quantity a thereof is introduced into the container C under atmospheric pressure conditions. This may conveniently be effected by a filler of the type disclosed in my Patent Re. 23,830, issued May 18, 1954. In general, the filler 10 includes a tank 11 having a dispensing orifice 12 adjacent the lower end and a valve 13 for controlling the flow through the dispensing orifice. Liquid is supplied to the tank 11 through a conduit 14 and a valve 15 is provided for controlling the fiow through the conduit into the tank. A float 16 is disposed in the tank for controlling the flow of fluid into the tank and, as illustrated, is arranged to actuate a switch 17 for energizing the solenoid 18 to open and close the valve 15 and maintain the liquid level of the product A in the tank 11 at a substantially constant level with respect to the orifice 12. A dispenser valve operating solenoid 19 is attached to the container 11, which last-mentioned solenoid is energized under the control of a timer 21 arranged to open the valve 13 for a preselected time interval to dispense a measured quantity of product into the container C.

In accordance with the present invention, the volatile propellant, sub-cooled to a temperature preferably substantially below its boiling point at atmospheric pressure, is dispensed into the container C on top of the relatively warm product a therein in such a manner as to contact only the surface layer of the product. With this arrangement, the violent agitation and boiling of the product, which normally occurs when the cold liquified propellant is introduced into the container on top of the warm product, is minimized with a consequent elimination of the liquified propellant therein.

4 I splashing of the product from the can. In addition, since the liquified propellant is introduced in such a manner as to only contact the upper layer of the product, the propellant, upon vaporizing, only chills the upper layer of the product a of the container. This thickens or solidifies the upper layer of the product in the container and minimizes the heat transfer between the lower layers of the product and the propellant thereabove sufiicient so that additional liquified propellant can be introduced on top of the thickened or semi-solid layer and will remain in this liquified condition without excessive losses until the can is subsequently sealed by the crimping of the dispenser valve thereto. Moreover, after the surface layer of the product has solidified, further liquid propellant can be introduced into the container at a more rapid rate without causing agitation and splashing of the product to reduce the filling time and minimize the loss of propellant.

It is essential that the initial quantity of liquified propellant be dispensed into the container on top of the product a therein with a very low velocity in a direction normal to the surface of the product and at a sufiiciently slow rate of flow to prevent the liquified propellant from penetrating an appreciable distance into the product a in the container sufiicient to become partially immersed therein. When the liquified propellant strikes the warm product, it immediately begins to vaporize and cool the product If the stream of liquified propellant is very small and if it strikes the surface of the product in the container with a Very low velocity, the initial portion of the stream of liquified propellant will substantially completely vaporize upon contact with the warm product and chill and solidify the surface area contacted thereby. As the surface area contacted by the stream thickens or solidifies, the heat transfer from the warm product to the liquefied propellant is reduced so that some of the stream does not vaporize but instead spreads across the thickened or solidified area to surrounding surface areas to chill the same. After the entire surface layer of the product in the container is thickened or solidified, further vaporization of the propellant is reduced to a low level and a layer of liquid propellant then builds up on top of the thickened or solidified layer of product.

If the initial' stream of liquified propellant strikes the product with excessive velocity, the propellant stream will penetrate below the surface layer of the product. This increases the amount of warm product contacted by the liquified propellant and therefore increases the amount of product which must be chilled with a consequent increase in the amount of propellant which is vaporized and lost during the filling operation. More importantly, however, is the violent agitation and boiling of the product which occurs when a portion or globule of the stream of liquified propellant becomes immersed in the warm product. The warm product heats and vaporizes the globule or globules of propellant very rapidly and the resultant rapid expansion of the propellant causes violent agitation of the liquid product and frequently causes splashing of the product from the can. The tendency of the propellant to become immersed in the product varies with different products dependent upon the relative specific gravity of the produce and propellant. When the product has a specific gravity very close to the specific gravity of the propellant, the liquified propellant must be flowed gently on top of the warm product with almost no velocity in a direction perpendicular to the surface of the product and at a sufficiently slow rate so that the propellant will vaporize substantially immediately upon contact with the surface of the product to thereby chill and solidify the surface layer thereof. However, when the product has a specific gravity appreciably higher than the specific gravity of the liquified propellant, the product will buoy up the liquified propellant and tend to inhibit immersion of the With such products, the velocity of the propellant stream can be increased somewhat.

{A timer 54 is p :of the solenoid-operatedvalve 27 and isia d to open asssfiec For example vaporizes at about -'26 Eat normal-atmospheric pressure. While satisfactory filling can be achieved when the liquifie'd propellant is'cooled to .40 to -45 F., the loss of pro- -pe llant is 'materiallyreduced when the propellant-issub- ='c'ooled -to a-lower temperature, preferably to 6 to #80 F.

7 container and, in'general, includes {a tank' 25 having a dispensing nozzle 26 and a solenoid 27 for controlling the fiow'through the A float 28 is provided for samewhen the liquid reaches a preselected ;upper level land to open when the liquid drops slightly below that evel.

The tankfZS is. also preferably refrigerateditomaintain: thev'olatile propellant D therein at a temperature: substantially below, its, boilingv point at atmospheric pressure: and for this purpose an evaporator coil 47 is disposed around thetank and is connected through conduit 48 and expansion {valve 49 and through conduit 50 to the discharge and return lines 42 and 44 of the refrigeration apparatus (see Fig. l).

In order to minimize the velocity at which the propellant D is introduced into the container C,. the dispenser tank25 is vented to the atmosphere as through a port 52 to maintain the liquid propellant under atmospheric pressure; and the size of the opening in the discharge nozzle'26 of liquified propellant thereabove is carefully controlled so as to .provide a relatively slow rate of flow of liquified propellant from the tank 25 into the container C. In the packaging of products such as paints having aspecific gravity appreciably greater than that of the propellant, it has been found that the liquid propellant will not penetrate into the warm product sufficient to become immersed therein when the head of liquid in the tank 25 is made only of the order offour or five inches above the located closelyadjacent the top the container'C and when therate of flow through the nozzle of at least the initial portion of the propellant is of the order of fifteen grams per-second. When the liquified propellant flows from the nozzle 26 into the container C, the velocity there is invsufiicient to cause the stream to penetrate appreciably below the surface of the paint a in the container and be partially immersed therein.

provided 1 for controlling energization dispensernozzle 26 and the nozzle is .6 I the valve for a preselected time interval and slowly dispense a quantity d of liquified propellant on top ofthe product a' in the container. The initial portion of liquified propellant introduced into the container vaporizes This thickens the surface layer of the product'a and has been found to markedly reduce the further transfer of heat from the product a to the propellant d thereabove. Consequently, additional propellant can be dispensed into the container on top of the thickened or semisolid layer Without further agitation or boiling of the product and without'undergoing excessive losses. As is apparent, the liquified propellant which volatilizes upon contact with the product is effective to purge the air from the container so that a separate purging operation is unnecessary.

In the packaging of some products which do not require-a very large amount of liquified propellantin the completed package, the time required to dispense the desired quantityof liquified propellant into the container,

even at the relatively low rate of flow effected through 'the nozzle 26, is not so large as to cause excessive losses of propellant due to prolonged exposure to the surrounding air.

jas shown is of'thefiu'i'd operated type which is connected throngh'a reversing valve 56 to a conduit 57 leading to "a source 'of'fluid pressure.

As previously described, the volatile propellant, upon *contacting the V I partially solidify the upper surface layer to a depth of about 4 inch. With some products, such as paint, the surface layer does not freeze solid but only thickens to a relatively dense layer. Consequently, with 'such products, those valves V employing a syphon tube v can be applied to the container after the propellant is introduced thereinto since the syphon tube can be easily forced through the thickened layer on the upper surface of the product. However, with those products which solidify to a very hard layer at a temperature near theboilingpoint of the propellant under atmospheric pressure, it is preferable to apply the valves V having a syphon tube loosely on the container C prior to the introduction to the propellant into the container andto displace the valve Von the container sufiicient to permit the propellant to be introduced into the container.

" Some products, such as paint, require a relatively large volume of liquified propellant to be introduced into each container. For example, when filling paint into a twelve ounce can, at least grams of the'propellant should be used. However, the filling of such relatively large quantities of propellant at the low rate of How effected by the propellant dispenser 25 would not only excessively increase the time required'for filling the container but would also increase the losses of propellant due to the prolonged exposure of the volatile propellant to the surrounding atmosphere. It has beenascertained, however, that after the initial quantity of the volatile propellant has been gently flowed on top of the surface of the product a to solidify or chill the upper layer of the prod not, that the subsequent propellant can be dispensed at a relatively more rapid rate on top of the thickened or hardened layer of product without causing agitation or boiling of the product.

-- provided.

. The second propellant '7 As illustrated herein, the second propellant dispenser is also of the type including a tank 61 having a dispensing nozzle 62 and a valve 63 for controlling the flow therethrough. A float 64 is provided in the tank for controlling the flow through the inlet conduit 65 which receives a supply of sub-cooled propellant from the heat exchanger 36. An evaporator coil 67 is provided around the container 61 and is connected through conduit 68, expansion valve 69 and conduit 70 to the discharge and return lines of the refrigeration apparatus 41 (see Fig. l). dispenser 60 is arranged to dispense the volatile propellant at a relatively more rapid rate than the first propellant dispenser 20 so as to thereby enable introduction of the desired amount of propellant into the container in a minimum time after the initial charge has been introduced thereinto by the first dispenser and, as shown, the float is arranged to maintain a relatively higher liquid head for more rapid flow through the nozzle. A timer 70 is provided for controlling energization of the valve 63 to thereby regulate the quantity of propellant dispensed by the dispenser 60.

In the specific embodiment illustrated, the container C must be moved from a dispensing position below the dispenser 20 to a position below the dispenser 60. It is to be understood, however, that the dispenser 60 may be so arranged as to permit introduction of propellant into the container C while the container is in position below the dispenser 20, the operation of the dispensers being so controlled that the dispenser 2.0 introduces at least the initial quantity of propellant into the container before the dispenser 60 is operated, to introduce the additional quantity of propellant.

The present method is thus arranged to purge the container and to eifect filling of cold propellant on top of warm product and may be used by itself in the packaging of volatile propellants and liquids which solidify or thicken at the boiling point of the volatile propellants. However, it is to be noted that the present method can desirably be used in conjunction with pressure filling apparatus to expedite the filling of containers requiring large quantities of volatile propellant. Thus, the warm prod uct a can be dispensed into the container and the liquified propellant d then introduced into the container on top of the warm product, either by the propellant dispenser 20 alone or in conjunction with the propellant dispenser 60, and in a quantity considerably in excess of the quantity which vaporizes in chilling the upper surface of the product. The valve V may then be crimped on the container as by the crimper 55 to seal the container and the container then passed to a pressure filler 81 which introduces the balance of the liquified propellant into the container. Since a substantial portion of the liquified propellant which appears in the final product is introduced into the container by the filler 20, or by the filler 20 in conjunction with the filler 60, it is apparent that the amount of liquified propellant which must be pressure filled is reduced. As the liquid dispenser 20 and the pressure filler 81 operate sequentially to dispense propellant into the containers, it is apparent that the overall filling time can be reduced materially. For example, in one filling line in which 90 grams of propellant were introduced into the can by a pressure filler, the maximum number of cans which could be filled was 15 per minute, with one type of dispenser valve on the can. When 15 grams of sub-cooled propellant was filled at atmospheric pressure, about grams vaporized in cooling the product and in purging leaving about grams of liquified propellant in the can when the valve was applied. The balance of the propellant (80 grams) was pressure filled. This permitted a speed up in the line so as to enable filling of 18 cans per minute. When 20 grams of the propellant in the final package was filled at atmospheric pressure, and the balance (70 grams) pressure filled, the line speed was increased to 21 cans per minute.

The pressure filler 81 may be of any conventional conrapid rate since the liquified struction such'as is illustrated in the patent to A. B. Mojonnier, No. 2,785,537, issued March 19, 1957. The propellant is supplied to the pressure filler through a conduit 82 and a mechanism, herein shown in the form of a fluid operator 83, is provided for operating the pressure filler under the control of a reversing valve 84.

A modified form of propellant dispensing apparatus is illustrated in Fig. 3 and is arranged to introduce propellant into the container in such a manner as to reduce the velocity of the propellant in a direction normal to the surface of the liquid product in the container C to substantially zero so as to prevent violent agitation or boiling of the product when the relatively cold propellant is introduced thereinto. This dispensery is particularly adapted for filling volatile propellant on top of those products such as shaving cream which do not have a specific gravity appreciably greater than that of the propellant and which may even have a specific gravity less than that of the liquified propellant. The initial quantity of liquid propellant is preferably introduced at a very slow rate to permit the propellant to vaporize substantially completely upon contact with the warm product and thereby chill and solidify the surface layer thereof. If the product density is .appreciably greater than that of the propellant, the propellant can be introduced at a relatively more propellant will tend to float .on the surface of a product even before the surface layer has solidified.

The dispenser itself may be of any conventional construction and is herein shown of the typeuineluding a tank 91 having a dispensing nozzle 92 and a valve 93 forcontrolling the flow thereto. A float 94 controls the flow into the tank 91 and is arranged to maintain the liquid propellant therein at a substantially constant level. A timer 95 is provided for controlling the valve 93 to effect dispensing of a measured quantity of liquid propellant from the rank. In accordance with the present invention, provision is made for battling the flow from the nozzle 92 to reduce the velocity thereof in a direction normal to the surface of the product in the container. For this purpose, the nozzle 92 is elongated and a sleeve 96 slidably disposed therearound and arranged to be extended and retracted into and out of the open mouth of the container C. A baffle plate 97 is attached to the lower end of the sleeve 96 to deflect the stream of propellant laterally across the surface of the liquid product in the container. The sleeve is normally urged to its retracted position as by a link 98 and spring 99. A mechanism, herein shown in the form of a solenoid 100 and a lever 101 connected to the solenoid, is provided for extending the sleeve 96 when the dispenser valve 93 is opened to dispense propellant from the tank 91. Conveniently, the solenoid 100 may be energized from the same timer 95 as is used to control the valve 93 so that the sleeve 96 and battle 97 are extended into the container when the dispensing operation is initiated and retracted upon completion of the dispensing operation. With this arrangement, the liquid propellant flowing through sleeve 96 is spread laterally over the surface of the product.

The foregoing method has several advantages over the present cold filling and pressure filling methods of packaging liquid products and volatile propellants. In regard to the cold filling method, it is to be noted that the present method is adapted for packaging those liquid products which cannot be packaged by the present commercial cold filling, namely those products which thicken or solidify at temperatures near the boiling point of the propellant under atmospheric pressure and which therefore cannot be accurately dispensed after being cooled. The present method is also adapted to fill cans more rapidly than by the straight pressure filling method. When a portion of the propellant is filled in this manner at atmosphericpressure and the balance pressure filled, it is apparent the time required for pressure fillingrcan With the present method, a large quantity of liquified propellant is present in the container at the time the valve is applied and the can is therefore filled with propellant vapor so that when the can is sealed, there is no overpressure. However, with the conventional purge only a small quantity of propellant is introduced into the container, the quantity being such that the propellant completely vaporizes before the valve is applied. In practice, it has been found that this does not remove all the air and that an overpressure exists in the containers after they are filled.

I claim:

1. The method of packaging a volatile propellant and a product which is liquid at ambient temperature and at least semi-solid at uct, and thereafter closing the container.

2. The method of packaging a volatile propellant and a product which is liquid at ambient temperature and at least semi-solid at the boiling point of the propellant at atmospheric pressure under atmospheric pressure comprising, introducing a thereafter closing said 4. The method of packaging a volatile propellant and a product which is liquid at ambient temperature and at least semi-solid at the boiling point of the propellant 10 under atmospheric pressure comprising, introducing a measured quantity of liquid product at substantially aman open container, maintaining a quantity of liquified propellant under atmospheric pressure and at a temperature substantially below its boiling point at that pressure, flowing a stream of the liquified propellant by gravity into the container on top of the warm product while maintaining the head of the liquid propellant sufficiently low to prevent the stream volatile propellant and a 6. The method of packaging a preselected quantity of volatile propelant and a bient temperature and at least semi-solid at the boiling No references cited.

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