US3461079A - Gelled propellant compositions useful in aerosol dispensers - Google Patents

Description

3,461,079 Patented Aug. 12, 1969 3,461,079 GELLED PROPELLANT COMPOSITIONS USEFUL IN AEROSOL DISPENSERS Irving B. Goldberg, 425 W. Aldine, Chicago, Ill. 60657 No Drawing. Filed June 11, 1964, Ser. No. 374,268

Int. Cl. C09k 3/30 US. Cl. 252-305 3 Claims ABSTRACT OF THE DISCLOSURE A composition set in the form of a gel which is stable under conditions of temperature and pressure that render normally gaseous aerosol propellant a liquid and will free the aerosol propellant as a gas upon reduction of pressure consisting of aerosol propellant in liquid form incorporated into a soap of fatty acids having 5 to 14 carbon atoms set as a solid using oleic acid as a gelling catalyst.

This invention relates to aerosol propellant compositions. More particularly, it relates to compositions containing liquefied gaseous propellants in a semi-solid form. Still more particularly, it relates to gelled propellant compositions and to combinations of propellant compositions and containers which are particularly adapted for dispensing substantially dry gases as well as liquids and solids suspensions from said container.

In accordance with this invention, compositions areprepared which comprise a liquid, produced by liquefaction of a material which is a gas at normal temperatures and pressures, admixed with a soap to form gelled propellant compositions for use in valved containers, for example, aerosol dispensers.

Aerosol dispensers generally operate at pressures up to about 100 pounds per square inch gauge, although containers for the retail trade capable of holding, for exam le, 14 ounces of liquid, are available which can be operated safely at higher pressures. The usual procedure today is to introduce into such an aerosol dispenser a propellant or propellant mixture capable of existing at room temperature and at a predetermined pressure, as an equilibrium mixture of liquid and gas.

Such aerosol dispensing systems have exhibited numerous disadvantages. The containers have a limited range of positions from which liquid other than the propellant can be dispensed, for example, as an atomized spray. Another disadvantage is the so-called spattering or dispensing of droplets of liquefied propellant together with the liquid intended to be dispensed, a result which can have deleterious effect, for example, when the product dispensed is a coating composition.

A further serious disadvantage of the aerosol systems has been the reduction in vapor pressure of the system during dispensing unless the discharge is limited to short periods of dispensing, i.e., short bursts. When dispensing is uninterrupted, the continuous vaporization of gas results in cooling of the liquid from which the gas is evolved. As the temperature is lowered, the vapor pressure of the system is reduced with the result that the spray pattern may be altered or the entire contents of the container cannot be dispensed without such a period of delay as is necessary to allow the container contents to return to atmospheric temperature.

Now it has been discovered that the disadvantages can be overcome by introducing into valved dispensing containers a propellant composition comprising an aerosol liquid and metal soap of relative short chain or lower fatty acids, which combination sets to a gel. In this propellant composition, the liquefiable propellant generally constitute-s between 50% and 99.5% by weight of the compositions.

Propellants useful in this invention may be varied depending upon the nature of the liquid solution, or the liquid medium of a solids suspension, etc., to be dispensed. Useful propellants, generally speaking, are the relatively water insoluble, saturated aliphatic hydrocarbons'and partially halogenated hydrocarbons having vapor pressures in the range between about 5 pounds to about 200 pounds p.s.i. gauge at 70 F., and preferably in the range betwen about 30 pounds and about pounds p.s.i. gauge. The propellants maybe formed of a mixture of two or more such compounds which, although the individual propellants may have vapor pressures outside the desired range, have, when combined, a vapor pressure within the stated ranges.

Straight chain saturated aliphatic hydrocarbons having vapor pressure suitable for the purpose are propane, butane, isobutane and cyclobutane. Other propellants useful alone or in admixture with other propellants are the saturated fluorinated or chlorinated or chlorfluorinated hydrocarbons, for example, the substantially water-insoluble halogenated alkanes having not more than two carbon atoms and at least one fluorine atom such as 1,1- difluorethane, l-monochlor, l-difluorethane, monofluortrichlormethane, monochlordifluormethane, dichlordifluormethane, 1,2-dichloro, 1,1,2,3-tetrafluorethane, and the like.

Soaps employed to form the gelled propellant compositions may be varied depending upon the nature of the liquid to be dispensed or the liquid component of material such as paint, insecticidal compositions, etc., which are intended to be dispensed.

In choosing an appropriate soap, the action or fatty acid anion or both may be varied to obtain the desired degree of solubility or insolubility of the soap in the fluid material being dispensed. In general, the useful soaps are metallic soaps of lower fatty acids selected from the group of fatty acids having about 5 to about 14 carbon atoms in the aliphatic hydrocarbon group.

In general, the higher the number of carbon atoms in the saturated or unsaturated aliphatic chain of the fatty acid anion, the greater the insolubility of the soap in an aqueous medium or in solvents. Useful acids for the purposes of this invention are the saturated or unsaturated fatty acids having about 5 to about 14 carbon atoms in the aliphatic hydrocarbon group, preferably about 8 to about 11 carbon atoms. Useful saturated fatty acids are valeric, caproic, heptoic, caprylic, n-nonyl-ic, capric, undecylic, lauri c, myristic, etc., acids. Useful unsaturated fatty acids are, for example, decenoic, 2-hexenoic, octenoic, etc., acids.

As was stated previously, the solubility characteristics of the soap may be controlled through the choice of cation. In general, ammonium cation, alkali metal cations such as sodium, potassium, lithium, alkaline earth metal cations such as calcium, barium and magnesium, etc., aluminum, lead, etc., cations are useful in forming the soaps. For example, ammonium myristate is soluble in methanol and ethanol and insoluble in ether, benzene, acetone, etc. Alkali metal soaps of lower fatty acids, for example, sodium laurate and certain alkaline earth metal salts of lower fatty acids have limited solubility in water and organic solvents. Aluminum and magnesium laurate have limited solubility in both aqueous media and organic solvents. Such a variation in properties makes mixtures of soaps a preferable embodiment of the invention because mixtures can be so combined as to give insolubility in a broad spectrum of mediums which may be dispensed.

When preparing a propellant composition, from about /2 by weight to about 50% by weight of the total propellant composition may be soap. Such amounts of soap may be introduced into a container simultaneously with or consecutively with the propellant liquid. Such a mixture will gel in the container. On other other hand, the gelled composition may be preformed, stored under appropriate conditions and transferred to a container as a solid gelled composition and the container closed by conventional procedures. When mixing propellant liquid and appropriate amounts of soap, the gelling may be accelerated by addition to the mixture of a catalyst, for example, oleic acid or other higher fatty acids.

When propellants embodying this invention are used to dispense liquids, the gelled compositions may have a specific gravity such that the composition will assume the same position relative to the liquid to be dispensed as a conventional aerosol or Freon liquid and the liquid to be dispensed will be forced from the container through a so-called dip tube which extends to the bottom of the valve container. Gelled compositions may also have a specific gravity such that the gelled mixture positions itself at the bottom of the container, in which event a short clip tube or extension of the valve casing need only extend a sufficient distance into a container to permit dispensing of substantially all of the liquid material present in the container.

In still other instances the gelled propellant may be used alone in the container to dispense a dry gas. In such cases, the valve need not have a dip tube at all.

A gelled propellant composition functions to eliminate dispensing of liquid propellant droplets regardless of the positioning of the container valve with respect to the bottom of the container. It also eliminates dispensing of droplets of liquid propellant because only dry vaporized gas is free to mix with the liquid to be dispensed, or in the case of dispensing only propellant, only dry gas is dispensed.

The invention will be further understood from the following examples which are provided without any intention that the invention be limited thereto.

Example I A mixture of 7.6 parts by weight of aluminum caprylate soap and 2.3 parts by weight of oleic acid was added to 142 parts by weight of propellant maintained at a temperature of F., said propellant consisting of 126.8 parts by weight of dichlordifluormethane (Freon 12), 15.2 parts by weight of perchlorethylene which provides a composition of 142 parts by weight under a pressure of between about 40 pounds and about 50 pounds gauge when the contents of a valved container attains room temperature of approximately 70 F.

A valved container A was filled with 151.9 grams of propellant composition which provided 142 grams of propellant. An identical valved container B was filled with 142 grams of liquefied propellant consisting of 126.8 parts of dichlorfiuormethane (Freon 12) and 15.2 parts by weight of perchlorethylene so that the vapor pressures in the containers were substantially equal at 70 F.

In order to test the comparative delivery of the two containers, they were arranged to spray simultaneously on a cycle involving intermittent dispensing over a period of five minutes, the intermittent spraying being for a period of five seconds followed by a wait of ten seconds. At the end of the five minute period there was a ten minute delay before the spray cycle was repeated.

When the spray time for container B totaled 1340 seconds, all of the propellant was spent. After a wait of one hour, the container exhibited no spraying ability.

When the spray time for container A, i.e., the container with gelled propellant composition, totaled 1760 seconds, the container indicated that propellant was spent. However, after a wait of one hour, the container A sprayed for an additional 95 seconds. After another hours delay, the container A sprayed for 20 seconds and after a third wait of one hour, the container A sprayed for 15 seconds.

The container A, containing gelled propellant, thus showed initial spraying time approximately one third greater than conventional propellant and an overall dispensing capacity of approximately 40% greater than container D which is representative of conventional dispensing container.

Example II A mixture of 7.6 parts by weight of aluminum caprylate soap and 2.3 parts by weight of oleic acid was added to 142 parts by weight of propellant maintained at a temperature of 0 F., said propellant consisting of 126.8 parts by weight of dichlordifluormethane (Freon 12), 15.2 parts by weight of perchlorethylene which provides a composition of 142 parts by weight under a pressure of between about 40 pounds and about 50 pounds gauge when the contents of a valved container attains room temperature of approximately 70 F.

The gelled propellant composition was formed in the container and an aqueous solution was added to substantially fill the container. The container then was closed by a valve of the type conventionally used for aerosol dispensing.

This container dispensed the aqueous solution in an appropriate spray pattern until substantially all of the solution had been discharged from the container.

In using the compositions of this invention, the soap and propellant and any petroleum distillate vapor depressant which may be added are introduced into the container wherein they form the gelled composition with the propellant when the propellant is added. The propellant may be introduced before or after the dispensing valve is attached to the container.

While a detailed description of the composition and package has been provided, it should be understood that numerous modifcations may be effected without departing from the spirit and scope as indicated in the appended claims.

I claim:

1. A composition set in the form of a gel which is stable under conditions of temperature and pressure that render a normally gaseous aerosol propellant a liquid and will free said aerosol propellant as a gas upon reduction in the pressure consisting essentially of an aerosol propellant in liquid form selected from the group consisting of liquefiable hydrocarbons and halogenated hydrocarbons which are gases at atmospheric temperature and pressures, between 1% and 4% by weight of the composition of oleic acid, said aerosol propellant and oleic acid being incorporated into a soap set as a solid which comprises lower fatty acid anion selected from the group consisting of fatty acids having 5 to 14 carbon atoms in the aliphatic hydrocarbon group and a cation selected from the group consisting of alkali metal, alkaline earth metal, aluminum, lead and ammonium cations.

2. The method of producing a composition which can be held as a gel at elevated pressures and will upon reduction of pressure free aerosol propellant in gaseous form which comprises admixing a liquid form of normally gaseous aerosol propellant selected from the group consisting of liquefiable hydrocarbons and halogenated hydrocarbons which are gases at atmospheric temperatures and pressures, under conditions of temperature and pressure to maintain said propellant a a liquid with between about 1% and 4% by weight of the composition of higher fatty acid catalyst for acceleration of gelation and a soap which comprises lower fatty acid anion selected from the group consisting of fatty acids having 5 to 14 carbon atoms in the aliphatic hydrocarbon group and a cation selected from the group consisting of alkali metal, alkaline earth metal, aluminum, lead and ammonium cations.

3. The method according to claim 2 in which said higher fatty acid catalyst is oleic acid.

(References on following page) References Cited UNITED STATES PATENTS Ray 447 Browning 252305 X Hunn 252-316 x 5 Cardwell et a1 2528.55 Fast et a1. 166-42 X Ira-1050 UNITED STATES PATENT OFFICE (s/ss) CERTIFICATE OF CQRRECTION PatentNo; 3,u61,o79 Dated August 12, 1969 Inventor(s) Irvine; B. Goldberg It is certified that error eppears in the above-identified patent a nd that said Letters Patent are hereby corrected as shown below:

Column 2, line 27, '53" shoul d be 2-,- column 2, line 3H,

"action" should be cation column'3, line 56, "dichlorfluormethane" should be dichlor'difluor'methane column 4, line 4, "D" should be B column 4, line 36,

"modifcations" should be modifications SIGNED AND SEALED APR 2 81970 EAL Attcst;

dward M. Fletcher, Ir. WILLIAM E, *SOHUYIJER,

fi 5 Offifier Commissioner of ratanta