US 3545162 A
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C. P. CLAPP Dec. 48, 1970 SYSTEM FOR FILLING INTERNALLY PRESSURIZED DISPENSING CONTAINER Filed June 11. 196s 3 Sheets-Sheet l M5L, da@
ATTORNEYS C. P. CLAPP Dec. 8, 1970 SYSTEM FOR FILLING INTERNALLY PRESSURIZED DISPENSINGnv CONTAINER Filed June ll. 1968 5 Sheets-Sheet l N .G m
ATTORNEYS C. P. CLAPP Dec. 8, 1970 SYSTEM FOR FILLING INTERNALLY PRESSURIZED DISPENSING CONTAINER Filed June ll, 1968 5 Sheets-Sheet .'5
la sim@ ATTORNEYS United States Patent O 3,545,162 SYSTEM FOR FILLING INTERNALLY PRESSUR- IZED DISPENSING CONTAINER Clarence P. Clapp, Milford, Conn., assignor to Aerosol Techniques Research Center, Incorporated, Milford, Conn., a corporation of New York Filed June 11, 1968, Ser. No. 736,198 Int. Cl. B65b 31 00 U.S. Cl. 53-22 8 Claims ABSTRACT F THE DISCLOSURE A system for lling aerosol type containers (containers the contents of which are discharged through a valve as a spray or a foam by internal pressure generated by a liquied material that is a gas at room temperature and pressure) wherein a very substantial amount of the air in the head space of a container is purged by incorporating a small amount of dichlorodilluoromethane in the concentrate. The concentrate contains an organic solvent in which the dichlorodiiluoromethane is soluble. The concentrate, including the solvent and the dichlorodifluoromethane, are introduced into the container while the interior of the container is exposed to the atmosphere. Subsequently the interior of the container is subjected to a vacuum equal to or somewhat lower than the vapor pressure of the blend including the solvent and the dichlorodiiluoromethane whereby enough of the dichlorodiiluoromethane evaporates to displace most of the air in the container over the concentrate. Thereafter while the interior of the container is still under the aforesaid vacuum a valved cap is sealed to the container as by crimping. The valved cap is placed on (but not sealed to) the container prior to subjecting the interior of the container to the vacuum but the vacuum must be present prior to introduction of the propellant gas so that air purging precedes propellant gas introduction. The propellant gas may be introduced either under the valved cap prior to the crimping or through the dispensing tube after crimping of the valved cap to the container.
BACKGROUND OF THE INVENTION Field of the invention A system for filling aerosol type containers characterized in that purging of air in the head space is effected by introducing into a solvent-containing-concentrate and/or solvent to be incorporated therein a highly volatile purging liquid consisting of a predominant amount of dichlorodiuoromethane. The purging liquid is introduced into the container while the interior of the same is under atmospheric pressure, following which a valved cap is loosely placed over the mouth of the container, the interior of the container is subjected to subatmospheric pressure and the cap is crimped after which a conventional gas propellant is introduced through the dispensing tube or the gas propellant is introduced under the cap prior to crimping, but after purging, in which event the vacuum is broken before crimping.
Description of the prior` art Present filling systems used for aerosol containers (containers the contents of which are discharged through a valve as a spray or a foam by internal pressure generated by a liquied material that is a gas at room temperature and pressure) are subject to the defect that consider- Fice able quantities of air are present in the head space over the container charge. The air, of course, contains oxygen. The presence of this oxygen is deleterious to the operation of the container for various reasons. One is that it tends to corrode the interior of the container whether the can be unlined or even if the container is lined. In the latter event the corrosion takes place through pinholes in the lining.
This corrosion is caused in part by the oxygen of the air in the head space and is enhanced by the presence of water in the charge. It is extremely difficult to provide a charge which is fully anhydrous. Some water almost invariably is present in one or more of the constituents of the charge which in combination with the air engenders the aforesaid corrosion.
Another ancillary problem associated with the presence of air in the head space is that the air provides a par'tial vapor pressure which adds to the total vapor pressure in the container. Under certain circumstances, particularly in warm temperatures or climates, this increased vapor pressure brought about by the presence of the air can raise the total vapor pressure to a value which exceeds acceptable standards. This is particularly true where the container is made of glass but also is a valid objection to the presence of massive amounts of air in the head space of a metal container.
Furthermore, there are various constituents which are present in the charge of the container, such for instance as perfumes and often other components, which are sensitive to oxygen in the head space so that the presence of air in substantial quantities in the head space tends to deteriorate such oxygen-sensitive materials. This in turn lowers, sometimes by a considerable amount, the shelf life of aerosol containers.
SUMMARY OF THE INVENTION It is an object of the present invention to provide a system for filling aerosol type containers which avoids the foregoing drawbacks and specifically which very appreciably reduces the amount of air (and, therefore, oxygen) in the head space.
It is a particular object of the present invention to provide a system of the character described in which the air in the head space is substantially purged by dissolving liquid dichlorodiuorornethane or an equivalent highly volatile liquid containing up to of said compound in the concentrate or solvent that is charged into the container, said liquid being soluble in said solvent the purging being carried out in a specially effective fashion by pulling a vacuum inside the container after the container has been charged under ambient room pressure but before the main body of the propellant has been introduced, such main body of the propellant being introduced either under the cap or through the dispensing tube of a valved cap that eventually is sealed to the container.
Another object of the invention is to provide a system of the character described which by minimization of the amount of air in the head space, reduces the tendency to corrosion of metal containers, reduces the vapor pressure present in the head space to more acceptable values and extends shelf life of aerosol containers charged with constituents including one or more materials that are sensitive to oxygen in the head space.
Other objects of the invention in part will be obvious and in part will be pointed out hereinafter.
The invention accordingly consists in the combinations of elements and series of steps which will be exemplified in the systems hereinafter described and of which the scope of application will be indicated in the appended claims.
BRIEF DESCRIPTION OF THE DRAWINGS In the accompanying drawings in which are shown various possible embodiments of the invention,
FIG. 1 is a iiow chart of one aerosol filling system which incorporates the invention;
FIG. 2 is a ow chart of another system incorporating the invention; and
FIG. 3 is a ow chart of still a third system incorporating the invention.
DESCRIPTION OF THE PREFERRED EMBODIMENTS In general the present invention is carried out by introducing a nontoxic, nonflammable, highly volatile liquid into the concentrate, including an organic solvent, or by mixing this liquid with the organic solvent itself which subsequently is added to the concentrate. The said highly volatile liquid is present in a rather small amount which will vary between about 0.5% to about 5.5% by weight of the total amount of the organic solvent, that is to say, the amount of organic solvent totally present in the concentrate or in the superconcentrate plus the balance of the organic solvent which subsequently may be added. This highly volatile liquid must have a low boiling point which is between about minus 10 F. to about minus 45 F. in order to avoid insufficient vapor pressure and any tendency to superheat which would in consequence hold the highly volatile liquid too tightly to flash off at a subsequent step in the process in which it displaces the air, i.e., purges the air in the head space prior to introduction of the main body of the propellant gas. The aforesaid highly volatile liquid principally constitutes a substance known as Freon 12 and also as P-12 this being dichlorodiuoromethane. The aforesaid highly volatile liquid necessarily includes at least 90% P-12 by weight and may constitute any fraction thereof from 90% to 100%. The highly volatile liquid may include also other highly volatile liquids such for instance as liquid Freon 114, which is dichlorotetrauoroethane, liquid Freon 22 which is difluoromonochloromethane, liquid n-butane, liquid isobutane and liquid propane. As is apparent from the premise just above stated, the additional materials in the highly volatile liquid, that is to say, the materials other than dichlorodifluoromethane, should not, in toto, exceed about 10% and may range down to 0%. Furthermore, the highly volatile liquid, which either constitutes all dichlorodifluoromethane and in any event not less than 90% thereof, and which is characterized by its stability, nontoxicity and nonammability, despite the presence of minor amounts of liquied gases which may, per se, be ammable when vaporized, is soluble in the solvent which is chargedinto the aerosol container either as part of the concentrate or as an additional liquid which is added to a superconcentrate, such solvent being organic. Obviously, in the case of the organic solvent being present in the concentrate, the solvent will contain active ingredients dissolved or dispersed therein, e.g., antiperspirants, cleaners, waxes, oils, solubilizing agents, paints, perfumes, natural and synthetic gums, resins, germicides, water repellants, esters, coloring agents, etc. The blend of the organic solvent used for the concentrate or added to the superconcentrate and the highly volatile liquid predominantly consisting of dichlorodifluoromethane will exert a total vapor pressure which is the function of the mole fraction of each volatile ingredient times its vapor pressure divided by the sum of the mole fractions of all the solvents present.
Examples of the organic solvents, which either constitute a part of the concentrate as charged into a container or which is added before, during or after the superconcentrate is charged into a container and which QlVGnts have had blended therewith the highly volatile liquid predominantly comprising dichlorodifluoromethane, include such standard organic solvents as are used widely in the aerosol container field (depending on the desired formulation) and are exemplified by alcohols such as ethanol and isopropanol (both essentially anhydrous), aliphatic petroleum derivatives such as Isopar E, mineral spirits such as Shells Mineral Spirit 150, aromatic petroleum derivatives such as xylene and toluene, esters such as isopropyl myristate, isopropyl adipate and diisopropyl palmitate, mineral oils, glycol ethers such as ethylene glycol nionobutylether, ethylene glycol monoethylether and ethylene glycol monomethylether, ketones such as acetone, methylethyl ketone, methylisobutyl ketone, chlorinated solvents such as perchloroethylene, 1,1,l-trichloroethylene, and turpentine.
It is also proper to mention at this point that dichlorodiuoromethane is preferred not only for its low-boiling point, nontlammability, nontoxicity and stability but also for its inertness, i.e., lack of tendency to chemically react with other components of the materials which are charged into aerosol containers in general, such for instance as all kinds of active ingredients used for discharge by the aerosol method, as Well as the propellants and solvents that are conventionally employed in this eld.
The total vapor pressure of the blend of the organic solvent employed and the highly volatile liquid which predominantly consists of dichlorodiiiuoromethane and which liquid is present in an amount between about 0.5% and about 5.5% by weight of the organic solvent, should, according to the invention, have a vapor pressure of not less than 5 p.s.i.a. (20 of mercury vacuum) nor more than about l2 p.s.i.a. (6 of mercury vacuum).
The new system is sufiiciently flexible so that the highly volatile solvent can be introduced as noted above either into the concentrate which will contain the organic solvent or it may be introduced into the organic solvent which is added to a superconcentrate which may or may not contain organic solvent, being added before, during or after introduction of the superconcentrate into a container.
An aerosol container is lled with the concentrate which includes the organic liquid, or the superconcentrate and organic solvent, the organic solvent in either instance having dissolved therein the highly volatile liquid described above, and this filling is performed with the interior of the aerosol container exposed to atmospheric pressure, the filling being carried out under ambient room temperature conditions such for instance as temperatures ranging between about 60 F. to about 80 F., the particular temperature not being critical and any temperature being acceptable at which personnel can perform efficiently. At this stage the aerosol container is not hermetically closed, although the cap may be in place but in such case will not be sealed to the container as by crimping. Moreover, at this stage, as previously mentioned, the highly volatile liquid will be present in the amount of about 0.5% to about 5.5 by weight of the organic solvent so that the combined vapor pressure of the solvent and highly volatile liquid will be between about 5 p.s.i.a. and about l2 p.s.i.a. Still further, at this stage the main body of the propellant liquiiied gas has not yet been introduced into the container. It has been observed and a somewhat more detailed comment on this feature will be made at a subsequent point, that the highly volatile liquid will not evaporate rapidly when mixed in the aforesaid proportions with conventional aerosol organic solvents. Indeed the highly volatile liquid will only be lost in small amounts from a concentrate or organic solvent over extended periods of quiescent standing in an unsealed tank having a lid. For instance if the dichlorodiiiuoromethane is present in an amount of 4% by weight of the organic solvent and the organic solvent is present either in a concentrate or by itself and furthermore if the organic solvent with or without the remaining ingredients of the concentrate are disposed in an unsealed tank with a lid at room temperature for as long as three (3) days there is only a loss of about 0.5% of the dichlorodifluoromethane which percentage is by weight of the solvent so that after this period of three (3) days, dichlorodifluoromethane still is present, in an amount of about 3.5% by weight of the organic solvent. Hence, after the aerosol containers have been filed to the amount desired -Wtih the concentrate containing the organic solvent and highly volatile liquid or a superconcentrate plus an organic solvent with the highly volatile liquid, the dwell time during which the fill is exposed to the atmosphere is not of critical importance insofar as loss of the dichlorofluoromethane is concerned except, of course, insofar as the dwell time lowers filling efficiency and ties up equipment and space.
Thereafter, as an important and critical factor of the invention, the interior of the aerosol container which at this time still does not have therein the main body of the liquied gas propellant therein, is evacuated to a vacuum of between about 12 p.s.i.a. and 3 p.s.i.a. preferably in a short time. The time is short for various reasons, one being a matter of economy in space and the other is the desire not to substantially exhaust all of the highly volatile liquid present in the fill. A satisfactory time is about one l (1) second. However, this time can range from about 1/3 of a second to about 11/2 seconds, satisfactory results being obtained throughout the entire range with the better results being secured over the longer periods of time of evacuation, bearing in mind that the longer periods of evacuation tend to tie up the equipment too long.
During this evacuation the highly volatile liquid tends to evaporate rapidly and its vapor to move upwardly through the existing head space in the can in the form of a cloud of vapor which pushes the air ahead of it and substantially fills the head space above the charge with the vapor of the highly volatile liquid, i.e., the dichlorodifluoromethane with minor percentages of the other highly volatile liquids. The displacement action of the vapor, moreover, takes place without a marked boiling and splashing of the liquid fill then present in the can so that the evacuation is essentially a clean operation not tending to disseminate particles of liquid out over the open top of the container and to fall on to equipment, personnel and the floor around the evacuation station and moreover not tending to lose the expensive active ingredients of the concentrate. The amount of the highly volatile liquid which evaporates during evacuation, although it performs the purging of the air with effectiveness as later will be pointed out by figures given, is not a substantial amount. For instance, when the vacuum is pulled for approximately one (1) second, about .3% of the highly volatile liquid (on the basis of its relationship to the organic solvent) is evaporated and in the main passed through the vacuum pump.
The mixture of the concentrate or superconcentrate and the organic solvent and the highly volatile liquid is filled into an open-to-the-atmosphere container by means of a conventional concentrate filler of a type well known to the art in varying amounts depending upon the nature of the particular fill and desire of the trade. Typically, the combined amount of said concentrate with its organic solvent and the highly volatile liquid is introduced into a container in an amount such as to leave a head space of at least 1A; but not more than about 4/s of the capacity of the container.
Next, a valve is placed over the top of the open con` tainer. The valve is part of a cap for the open mouth of the container. The valve is not sealed, e.g., by crimping, to the container so that the placement of the valve does not hermetically seal the container which thereby remains open to the atmosphere.
Next, pursuant to the invention, the requisite vacuum is pulled which causes the purging of most of the air in the head space.
Subsequently, the cap with its valve is crimped to the container to hermetically seal the interior of the container from the atmosphere and the can is gassed with the main body of propellant liquid, either step being first and the other second.
The vacuum employed is a function of the vapor pressure of the blend of the highly volatile liquid and the organic solvent.
The container is gassed in any conventional manner. For instance, it may be gassed through the dispensing tube with the dispensing valve open. It also is within the scope of the present invention to gas the container immediately prior to sealing and while the container is still in a subatmospheric condition. Such method of gassing is known as under-the-cap gassing. A liquid gas in such instance is introduced into the container through the annular crevice which surrounds the juncture between the cap and the mouth of the container.
It will be appreciated that the gassing referred to constitutes the introduction of the main body of a conventional liquied gas propellant. Such gassing is, per se, well known in the art and forms no part of the present invention except that its place in the sequence of steps constituting the present system is important, that is to say, the gassing must be performed subsequent to evacuating the then existing head space in the interior of the aerosol container so as to give the highly volatile liquid time to purge most of the air.
The final head space which is present after gassing and which constitutes the space above the concentrate and the blend of organic solvent and the highly volatile liquid, and the main body of the liquified gas propellant will vary in accordance with manufacturing specifications. It is usual, and this applies to the present invention, for the final head space to vary between about 10% and about 30%. Less than about 10% would not leave sufficient room for thermal expansion and more than about 30% would be considered uneconomical. As to the amount of gas, i.e., main body of liquid gas propellant, introduced subsequent to evacuation for purging of air, this too will vary widely depending upon trade usage, manufacturers specifications and state of the art. As little as 3% by weight of liquified gas propellant, up to as much as by weight of liquified gas propellant may be employed, the percentage by weight of the main body of the liquified gas propellant being based upon the total till of the container which includes not only the main body of the liquified gas propellant but also the concentrate, the organic solvent and the highly volatile liquid.
Further, with respect to the degree of evacuation, i.e., the value of the vacuum pulled, it preferably will be n the range of between about 12 p.s.i.a. and 2 p.s.i.a. which corresponds to about 6" of mercury to about 26" of mercury. The vacuum which prevails during the evacuation (air purging) step preceding sealing and preceding the introduction of the main body of the liquified gas propellant should be in a range between the vapor pressure of the blend of the organic solvent and the highly volatile liquid and a lower value which is not more than about 3 p.s.i.a. below said Vapor pressure of the blend. Thus, by way of example, a blend of organic solvent and highly volatile liquid having a vapor pressure of 5 p.s.i.a. should be evacuated prior to crimping (sealing) and gassing under a vacuum of between 5 p.s.i.a. and 2 p.s.i.a. On the other hand a blend of organic solvent and highly volatile liquid having a vapor pressure of 12 p.s.i.a. should be evacuated prior to crimping (sealing) and gassing at a vacuum of between 12 p.s.i.a. and 9 p.s.i.a.
Of course, the vacuum pulled is maintained during crimping if this is first performed Iand also will be maintained during the start of propellant filling if under-thecap propellant filling is first employed.
The organic solvent/highly -volatile liquid of the concentrate to head space volume must be between about 'Ms to about Ms at one end of the range to about 1 to about 4 at the other end of the range. In the first instance Iwhich is about 'Vs to 1A, the minimum head space thus provided is needed to supply room for the main body of the liquified gas propellant and for thermal expansion of the liquid contents of the aerosol container. At the other end of the range, which is about l to about 4 Athe maximum head space ensuing is to insure a supply of highly volatile liquid/organic solvent to purge the head space during evacuation.
One might expect, as has been mentioned above, that retention of the highly volatile liquid in the organic solvent and/or the concentrate containing organic solvent, where such a highly volatile liquid as described is employed, would result in high losses of the highly volatile liquid during handling and filling and evacuation (for air purging) and would cause foaming, bubbling and inability to control the composition and weights in the filling and evacuation equipment. Concentrations higher than about 5.5% by weight of the highly volatile liquid in the organic solvent or carrier containing the organic solvent cannot be handled pursuant to the present invention at ambient. temperatures and this, therefore, constitutes the higher end of the range of said highly volatile liquid heretofore mentioned. Greater amounts than said 5.5% by weight of the highly volatile liquid would render it impossible to fill controlled formulations under mass production conditions into aerosol containers. The present inventor has tested mixtures in the indicated range of between about 0.5% and about 5.5% by weight of the highly volatile liquid to the organic solvent under both laboratory and high speed production conditions and has found that these mixtures do not boil, foam or change in composition sufficiently to noticeably affect utility under the severe handling experienced due to agitation encountered l in pumps, filters, fillers, etc., providing that the Vapor pressure of the blend of highly volatile liquid in the organic solvent is in the indicated range of about 5 p.;.i.a. to about l2 p.s.i.a. and the vacuum pulled for purging is within the indicated limits. Under these parameters the charge can be handled during filling and appropriate evacuation can be effected without deleterious effects and while insuring that a sufiicient quantity of the highly volatile liquid vapors rises from the organic solvent to displace substantially all the air in the head space of the container whereby air removal is greatly improved and the process is controllable with predictable compositions and results. Essentially, the compositions are controlled because of a predictable, repeatable and consistent change in the composition under the aforesaid controlled conditions which causes only a slight loss of the highly volatile liquid during evacuation. Actually, about 5% to of the highly volatile liquid, based on the original amount of the highly volatile liquid present and dissolved in the organic solvent, is removed from the organic solvent/highly volatile liquid blend during the purging of air from the head space of the container. lf all conditions are held substantially constant, the amount of the highly volatile liquid lost during evacuation is highly consistent, yielding highly uniform compositions resulting in very uniform vapor pressures in the head space, resulting in highly uniform displacement of air and elimination of most of the undesirable oxygen that would be present if any other methods were followed.
"lt is also interesting to observe that the ratio of the highly volatile liquid to the organic solvent does not change in composition significantly during routine storage preceding filling where the produce is not agitated and, therefore, this combination of the organic solvent and the highly volatile liquid can be held in nonpressurized vessels for prolonged periods of time without significant changes in composition. This is very desirable in manufacturing procedures inasmuch as it permits large amounts of the blends of organic solvent and highly volatile liquid to be prepared in advance.
It is possible to dissolve the highly volatile liquid in the organic solvent by straightforward injection with stirring since the equilibrium of the highly volatile liquid organic solvent mixture favors solubilization of dichlorodifiuoromethane up to the upper limit indicated, to wit, 5.5 by Weight of the Solvent. It should also be mentioned that the highly volatile liquid can be incorporated in the organic solvent in Ivarious other manners, a typical mode being sparging which constitutes introduction of a small stream of the highly volatile liquid into a body of a larger stream of the organic solvent either by itself or as part of the concentrate.
Set forth below are several examples of the various compounds and steps employed in different systems following the present invention:
EXAMPLE I Aerosol antiperspirant.-The first step is to fill an open aerosol container with a concentrate composed of the following:
Percent by weight Aluminum chlorhydrol/propylene glycol complex 59.3% by weight of the foregoing with respect to the finally complete weight of the contents of the container are introduced into the container at atmospheric pressure and at a temperature of 68 F. It should be observed at this point that 0.3% of the dichlorodifiuoromethane propellant which is the highly volatile solvent subsequently will be lost during evacuation for air purging so that the remaining amount of this ll will be 59%.
The foregoing fill is left in the aerosol container for any desired period of time which usually will be in the vicinity of one minute and will be wholly determined by the speed of the filling, evacuation and capping production line.
INext, a valved cap is loosely placed over the mouth of the container with the aforesaid concentrate therein.
The next step consists in applying a Ivacuum to the interior of the container above the concentrate, the vacuum is at 15l of mercury absolute which will vaporize part of the dichlorodifluoromethane volatile liquid and thereby purge the space over the concentrate to remove the air therefrom. The vacuum is applied for one second. The container has a capacity of cc.
While the container still is under vacuum, the cap is crimped. Machines which apply a vacuum to the interior of a container and subsequently, i.e., within about a second, crimp (seal) the valve cap to the container while the container is still under a vacuum are well known and, therefore, will not be described in detail. By way of example, three (3) such machines are the Nalbach crimper, Model No. 8HVC made by Nalbach Engineering Company; the Elgin filler, Model No. 6839 made by Elgin Engineering Company; and, the Cozzolli filler, Model No. LF 1640 made by Cozzolli Machine Company.
At this stage, there is still a substantial head space but the interior of the can is at subatmospheric pressure and has been substantially purged of air and the head space is substantially filled with -vapor from the dichlorodifluoromethane.
Next, it is necessary to gas the container which constitutes the insertion of the main body of a pressurized liquified gas propellant in a quantity sufficient to act as a propellant for the active ingredients of the concentrate. The particular propellant employed in this example is dichlorodifluoromethane, although obviously other well known propellants will work equally well. 41% by weight of the said propellant is added to the can to make up 100.3% by weight of the concentrate plus propellant, 0.3% of the dichlorodiiiuoromethane in the concentrate being lost during the evacuation step immediately preceding crimping and, of course, preceding the addition of the much larger amount of the dichlorodifiuoromethane that is added during the gassing step. The iinal head space is 20% by volume.
EXAMPLE II Aerosol hair spray-In the iirst step, a concentrate is added composed of the following constituents:
Percent by Weight Polyvinylpyrrolidone 2.50 Perfume 0.25 Ethanol (anhydrous) 92.75
Dichloroditluoromethane highly volatile liquid 4.50
54.30% by weight of this concentrate is charged into an aerosol container open to the atmosphere. Subsequently, a valved cap is loosely emplaced and the interior of the container is subjected to a vacuum of mercury absolute to remove air and vaporize part of the highly volatile liquid (an amount of about 0.3% of this liquid is Vaporized) to perform the air purging operation. The filling is done at atmospheric pressure and room temperature of 68 F. The evacuation proceeds for one 1) second and then the cap is crimped in place (sealed) with l a hermetic seal around the mouth of the container. The container has a capacity of 290 cc. Finally, the now sealed container is gassed through the discharge Valve with 46% by weight of the main body of a liquied gas propellant constituting 48% by weight of dichlorodiiiuoromethane and 52% by weight of dichloromonoiiuoromethane. The final head space is by volume.
EXAMPLE III Aerosol hair spray-This example differs from the preceding examples by employing a superconcentrate plus a straight solvent ill wherein the solvent contains the highly volatile liquid. The superconcentrate is composed of the following:
Percent by weight Polyvinylpyrrolidone 12.50 Perfume 1.25 Ethanol (anhydrous) 86.25
10% by weight of the superconcentrate is charged into an open aerosol container having a capacity of 290 cc. at a room temperature of 68 F. Concurrently therewith or subsequently thereto or prior thereto, the order of the steps being inconsequential, there is charged into the container a blend of organic solvent and highly volatile liquid composed as follows:
Percent by weight Ethanol (anhyrous) 95.50
Dichlorodiiluoromethane highly volatile liquid 4.50
The amount if this blend charged is 40.3% by weight, an amount of 0.3% of the highly volatile liquid evaporating during the subsequent evacuation.
Next a valved cap is loosely emplaced and the interior of the container is subjected to a vacuum of 12" mercury absolute to remove air and vaporize part of the highly volatile liquid. While the interior of the container still is under this vacuum, the cap is crimped to hermetically seal the container. 'Thereafter the container is gassed with 50% by weight of the main body of a liquified gas propellant composed of 48% by weight of dichlorodiuoromethane and 52% by weight of trichloromonouoromethane. It will be found that vaporization of the highly Volatile liquid purges the head space, prior to gassing of substantially all of the air.
With respect to the foregoing three (3) examples, it is pointed out that although water is not mentioned, it is present. For instance in Example I, the aluminum chlorhydrol/propylene glycol complex contains approximately 5 to 10% by weight of water and in Examples II and III, the polyvinylpyrrolidone contains approximately 6% by weight of water. Also the anhydrous ethanol in Examples I through III, is never truly bone dry. It usually contains about 0.1% by weight of water. The final head space is 15% by volume.
EXAMPLE IV Aerosol-oil-in-water emulsion furniture polish-This example differs from the preceding three (3) examples (aside from its difference in active ingredients) principally in that there is used for the lill (exclusive of propellant) a mixture of water and concentrate solvent which are mmiscible but which will form an emulsion. Into a 290 cc. open container, there first are charged two I'ills. The fills may be charged in succession, with either iirst, or concurrently. One lill is composed of 99% by weight of water and 1% by weight of polyoxyethylene sorbitan monooleate making up 100%. 75% weight of this ll is charged into a container. The second till which is charged into the container is a concentrate composed as follows:
Percent by Weight Isopar E 85.50 Dimethyl polysiloxane 10.00 Mineral oil 1.00 Lemon oil 1.00
Dichloroditluoromethane highly volatile liquid 2.50
20.2% by weight of this lill is introduced into the can making a total of 95.2% by weight. Isopar E is an organic solvent made by Humble Oil and Refining Company and having the following characteristics:
Aniline point-l65-l75 F. Aromatic content, weight percent-0.10 max. Specic gravity:
60/ 60 F.-0.7227 Distillatiom Initial B.P.--240 F. 50% B.P.-245-260 F. Dry point-290 F.
The container now has a 'valve cap loosely emplaced over the mouth thereof, the container having been filled at atmospheric pressure and room temperature of 68 F. The space over the till is evacuated to 21" mercury absolute to remove air by purging and vaporization of part of the highly volatile liquid, then while still under vacuum the cap is crimped to hermetically seal the same to the can. The container has a capacity of 290 cc.
The next steps are to agitate the container to form an emulsion and to gas with liquid isobutane. These two steps are interchangeable in order. The amount of isobutane added is 5% by weight to make up 100% of the total iill. Approximately 0.2% of the highly volatile liquid is lost during the evacuation operation, that is to say, about 2.3% of the original 2.5% of said liquid, in the 20.2% by weight of the concentrate remains. The final head space is 25% by volume.
EXAMPLE V Aerosol water-in-oil furniture polish-First two liquid iills are added at room, temperature and pressure. The order of the two fills is of no consequence, either can be rst or both can be added together. IOne till is 100% l 1 water, 50% by weight of water is added. The second iill is the concentrate which is composed as follows:
Percent by weight Mineral Spirits 150 83.70 Sorbitan oleate 3.50 Glyceryl monooleate 1.80 Dimethyl polysiloxane 6.00 Soluble wax 3.00
Dichlorodifluoromethane/isobutane (90/10) highly volatile liquid 2.00
37.2 by weight of the second till is employed, the 0.2% being lost by evaporation during evacuation. The evaporation is principally of the highly volatile liquid. It will be observed that the highly volatile liquid in this instance is 90% by weight of dichlorodiuoromethane and 10% by weight of isobutane. Thereafter, the steps are substantially -as above described which consists in loosely emplacing a valve cap, pulling a vacuum in the interior of the container of about 20 mercury absolute to remove air and vaporize a part of the highly volatile liquid for the purpose of purging the air. While still under vacuum the valve cap is crimped to hermetically seal the can. Then the can is agitated and gassed in any order, the gas added is 100% dichlorodifluoromethane in an amount of 13% by weight thereof to make up the full 100% of the fill. The container has a capacity of 420 cc. The nal head space is 20% by volume.
The Mineral Spirits 150 is an organic solvent made by Shell Chemical Company having the following characteristics:
Aniline point-151 F. Aromatic content, percent by volume-3 Specific gravity:
60/60" F.-0.777 Distillation:
Initial B.P.-323 F. 50% B.P.-342 F. Dry point-380 F.
EXAMPLE VI Aerosol water-in-oil furniture polish-The rst step is to ll an aerosol container of 560 cc. capacity with 87.2% by lweight of a concentrate composed as follow:
Percent by weight The ll is carried out at atmospheric pressure and room temperature of 68 F. as usual with the can open, then the can is loosely covered with a valve cap and a vacuum pulled to 20 of mercury absolute to remove air and vaporize part of the highly volatile liquid. r[he amount of liquid volatilized is about 0.2% so that the concentrate ll thus constitutes 87% by weight. With the vacuum maintained, the cap is crimped to the container to hermetically seal it. Thereafter, the container is gassed with 100% dichlorodiuoromethane in an amount of 13% by weight. The nal head space is 20% by volume.
In all of the foregoing examples, the gassing is performed after sealing through the discharge valve which is Opened for the purpose. However, if desired, in all of these examples the filling can be performed by the socalled under-the-cap method followed by sealing of the valved cap to the container which method is well known per se and a typical machine for this purpose is the Kartridge Pak under-the-cap iiller, Model No. 1951-9 made by the Kartridge Pak Company, For the purpose of completeness, it is mentioned that a typical gasser that can be used for gassing through the opened discharge valve is a Keiffer gasser Model No. 3-12, an alternate being Model No. 3-18. These are made by the Keiifer Gas J et Company.
In all instances where no mention is made of the period for which the vacuum is pulled in the interior of the container to evaporate a part of the highly volatile liquid for air purging purposes, the time is one second.
In order to assist in understanding the invention, ow charts have been provided as part of this disclosure. These charts schematically illustrate the apparatus and steps involved.
Referring to FIG. l, the reference numeral 10 denotes a tank either exposed to the atmosphere or vented to the atmosphere or covered by a lid not hermetically sealed thereto. In this tank 10, the concentrate of any of the preceding examples is mixed or there is disposed any of the sundry lls. It will, of course, be understood that ingredients placed in this tank will in each instance depend upon the desired formulation and the invention is not to be limited to the specific examples above given. The reference numeral 12 denotes a supply tank in which there is disposed a liquied gas which is highly volatile and which consists of at least 90% of dichlo-rodiiluoromethane. A valve 14 yconnects the tank 12 to a line 16 that runs through a valve 18 to the tank 10. Another valve 20 in a line 22 connects the tank 10 to a gasser 24. When the valve 20 is closed and the valve 18 is opened the highly volatile liquid will be introduced into the mixing tank 10, this arrangement being utilized when it is desired to add the highly volatile liquid directly to the concentrate which concentrate also includes an organic solvent such as described above wherein the highly volatile liquid is soluble. The rate of ow and duration of introduction of the highly volatile liquid into the tank 10` is such as to obtain the desired (0.5% to 5.5% by weight of the organic solvent) concentration of the highly volatile liquid in the concentrate which contains the organic solvent. A Valve 26 is disposed in a line running from the line 116 to a sparger 28. The sparger is in a line 29 running from the mixing tank 10 to a concentrate ller 30 which may be the Elgin or Cozzolli ller aforementioned. lf the highly volatile liquid is not introduced through the valve 18 into the mixing tank, said liquid may be introduced in the desired proportions into the concentrate through the sparger 28.
The concentrate ller 30 lls concentrate into open aerosol containers at room temperature and pressure, the concentrate containing from 0.5% to 5.5% by weight of the highly volatile liquid in the organic solvent with the highly volatile liquid dissolved in said solvent.
From the concentrate filler 30 the open containers containing the concentrate and highly volatile liquid are passed along a path 32 (along which valved caps are loosely emplaced on the open mouths of the containers) to a vacuum crimper 34, e.g., the aforesaid Nalbach crimper. Here, a vacuum is drawn and held for 1/a to 11/2 seconds for each container and then the valve caps are then crimped (sealed) in place. When the caps are crimped in the crimper the aerosol containers will have the concentrate and dissolved highly volatile solvent therein and at the same time the head space above the liquid in the can will be undef a vacuum. Then, the aerosol containers move along the path 36 t0 the gasser 24 which may be the aforesaid Keiifer gasser. Here the main body of the liquified gas propellant is introduced. This may be the same liquied gas as the highly volatile liquid in which event the gas is loaded from the tank 12 through the opened valves 14 and 20 and the line 22. At this stage, i.e., after the gas till, the aerosol container is ready for distribution.
It will be found that the head space in the containers has comparatively little air in it. Typically, there will be about 10% by volume of air left in the head space which means that the amount of oxygen is about 2% by volume. Such containers are highly stable, have a long shelf life, have little corrosion and have little product deterioration. The amount of air can be reduced to as little as 0.5 by volume by pulling the lowest vacuum within the parameters as above set forth and pulling it for the longest mentioned period of time. Also, the amount of air present will be reduced by adding up to by weight of one or more highly volatile liquids having a lower boiling point than dichlorodiuoromethane. It has been found that even up to a residue of by volume of air in the head space using the purging system of the present invention produces a product which is considerably superior to those now being marketed.
In FIG. 2 the reference numerals 10, 12, y14, 16, 18, 20, 22, 26, 28, 30 and 32 denote components which are the same and are connected and are used in the same manner, as those detailed in FIG. 1. However, in FIG. 2, the open containers leaving the filler 30 along the path 32 along which valved caps are loosely lemplaced in the mouths of the containers, instead of being introduced into a vacuum crimper or sealer 34 and thereafter moved along a path 36 to a gasser 24, are led along the path 32 to an underthe-cap filler 38, in which the containers are gassed from the tank 12 with a main body of liquied gas propellant from the tank 12 and then sealed to the valved caps.
In FIG. 3 a mixing tank A40 is provided in which a superconcentrate is mixed, said tank being at atmospheric pressure. The reference numeral 42 denotes a supply tank for the highly volatile liquid and the reference numeral 44 a storage tank for an organic solvent such as anhydrous ethanol. A valve 46 connects the tank 42 to a line 48 that has a branch line 50` including a valve 52. A valve 54 also connects the tank 44 to the line 50. A valve 56 connects the line 48 to a sparger 58 and a valve 60 connects the line 48 to a through-the-valve gasser (not shown) or to an under-the-cap ller 62. The active ingredients are blended in the mixing tank 40 with the organic solvent fed from the tank 44 and, if desired, with the desired amount, within the range previously indicated, of the highly volatile liquid so as to have present from about 0.5 to about 5.5% of said liquid by weight of the total amount of the organic Solv-ent included in a filled container. The ingredients of the superconcentrate are so proportioned that said superconcentrate can be blended with an additional amount of organic solvent to form a concentrate composed of up to 50% by weight of the superconcentrate. The superconcentrate is fed along a line 64 from the mixing tank to a filler =66 which introduces the proper amount of superconcentrate to open aerosol containers. The containers (still open) are led along a path 68 to a second filler 70 `where organic solvent from the tank 44 is fed through a line 72 to make up the balance of the solvent needed to incorporate a correct proportion of the solvent in the concentrate. Now the containers in which a proper amount of concentrate plus dissolved highly volatile liquid is disposed are led along a path 74 during which valved caps are loosely emplaced over the open mouths of the containers. The path 74 feeds the containers to the under-the-cap filler 62, which evacuates the containers to the proper indicated degree, then fills the containers with the main body of liquilied gas propellant and crimps the caps to the containers to provide nished aerosol containers. Alternately the path 74 feeds the containers to a vacuum crimper, such as the crimper 34, which rst evacuates the containers to the proper degree and then crimps the caps to the containers. The sealed, evacuated containers then are led to a gasser (not shown) such as the gaser 24, which introduces the main body of liquied gas propellant through the container dispensing valves which are held open for this purpose.
It thus will be seen that there are provided systems which achieve the several objects of the present invenuon and which are well adapted to meet the conditions of practical use.
As various possible embodiments might be made of the above invention and as various changes might be made in the embodiments above set forth, it is to be understood that all matter herein described or shown in the accompanying drawings is to be interpreted as illustrative and not in a limiting sense.
Having thus described the present invention, there is claimed as new and desired to be secured by Letters Patent:
1. In a method for lling an aerosol type container, constituting a container having a valved cap hermetically sealed to the container mouth, and in which container are disposed a concentrate composed of at least one active ingredient and an organic solvent and also a liquiiied gas propellant: that improvement including incorporating into the concentrate a nontoxic, nonilammable, stable, highly volatile liquid having a boiling point of from about -l0 F. to about 45 F., which is inert to the concentrate and propellant and which is present in an amount of from about 0.5% to about 5.5% by weight of the organic solvent, said highly volatile liquid including at least by weight of dichlorodiuoromethane and from l0% to about 10% by weight of other highly volatile liquids, the total vapor pressure of the blend of organic solvent and highly volatile liquid being between about 5 p.s.i.a. and about 12 p.s.i.a., introducing the concentrate, including the highly volatile liquid, into a container open to the atmosphere, then evacuating the space in the container above the concentrate and highly volatile liquid to a vacuum of between about 3 p.s.i.a. and about 12 p.s.i.a. for about Mi second to about 11/2 seconds so as to purge most of the air above the concentrate with the vapor from the highly volatile liquid, said vacuum being between about the vapor pressure of the blend and about 3 p.s.i.a. below the vapor pressure of the blend, and, subsequently, hermetically sealing a valved cap to the mouth of the container and introducing the main body of the propellant into the container.
2. A method as set forth in claim 1 wherein the other highly volatile liquids in the 0% to about 10% by weight of the highly volatile liquid are selected from the class consisting of dichlorotetrailuoroethane, diuoromonochloromethane, n-butane, isobutane and propane.
3, A method as set forth in claim 1 wherein the organic solvent is selected from the class consisting of alcohols, aliphatic petroleum derivatives, mineral spirits, aromatic petroleum derivatives, esters, mineral oils, glycol ethers, ketones, chlorinated solvents and turpentine.
4. A method as set forth in claim 1 wherein the container is filled with the concentrate including the highly volatile liquid, so as to leave a head space volume of about 1A; to about Vs.
5. A method as set forth in claim 1 wherein the final head space volume of the sealed, gassed container is about 10% to about 30% of the volume of the container.
6. A method as set forth in claim 1 wherein the residual air contained in the final head space of the sealed, gassed container is from about 0.5 by volume to about 15% by volume.
7. A method as set forth in claim 1 wherein the residual air contained in the iinal head space of the sealed, gassed container is from about 0.5 by volume to about 10% by volume.
8. A method as set forth in claim 1 wherein the period of evacuation is about one (1) second.
References Cited UNITED STATES PATENTS 3,224,158 12/1965 Baumann 53-22 3,336,720 8/1967 Honish 53--22 TRAVIS S. McGEHEE, Primary Examiner U.S. Cl. X.R. 53-36