Drug – bio-affecting and body treating compositions – Effervescent or pressurized fluid containing – Organic pressurized fluid
Reexamination Certificate
1999-05-28
2001-05-29
Bawa, Raj (Department: 1626)
Drug, bio-affecting and body treating compositions
Effervescent or pressurized fluid containing
Organic pressurized fluid
C424S076100, C424S401000, C424SDIG001, C514S063000, C514S938000
Reexamination Certificate
active
06238646
ABSTRACT:
TECHNICAL FIELD OF THE INVENTION
This invention is directed to aqueous aerosol compositions, particularly for the delivery of an atomized oil such as a fragrance oil, insecticidal oil and medicinal oil.
BACKGROUND OF THE INVENTION
In the past, different aerosol formulations have been used to deliver atomized oil particles. One type of aerosol composition contained an oil, co-solvent and propellant typically for dispensing a small amount of an oil, such as a perfume. A second type of aerosol used simply an oil and propellant. These aerosols were called dry systems because the components vaporized upon spraying. A third type of aerosol is an aqueous based system which complies with EPA Regulations for Volatile Organic Compounds (VOC) primarily because they have water as the major component. One of the major problems with an aqueous aerosol has been the need to shake the system before use, just as when one mixes oil and vinegar they separate, the same thing occurs with this system. Typically, a “shake before using” statement is on the label of these products to avoid spraying only one phase through the dip tube of the spray can while the other phase remains in the can. In many cases, it is not practical or possible to shake the container before use and, thus, these systems have limitations. Where room air fresheners are formulated employing the three types of aerosols, usually about 25-50% of a perfume is contained in the first type, about 2-10% perfume is contained in the second type, and the third type usually contains about 1% perfume.
Two main types of water-based aerosols have been known, namely, a three-phase system and a two-phase system. The three-phase aerosol system is formed when using a propellant such as propane or butane which is insoluble in the water phase. These three-phase aerosol systems need to be shaken properly before use. Two-phase aqueous aerosol systems consist of a homogeneous liquid phase and a gaseous phase. The liquid phase usually contains the active ingredients, solvents and liquified propellant. Homogeneity is achieved by means of a water soluble propellant such as dimethyl ether (DME). These types of aerosols need not be shaken before use. However, it has been difficult to obtain homogeneous DME-water mixtures which are stable upon standing. Attempts have been made to solve the stability problem by developing special perfumes or by the addition of special solvents. U.S. Pat. No. 4,382,078 is an example of a prior approach to solve the stability problem by employing a copolymer of ethylene oxide and propylene oxide as a surfactant to retain the active ingredients in the liquid phase.
Furthermore, in this '078 patent, with increasing amounts of fragrance oil, increasing amounts of surfactant are required. Increased surfactant results in non-volatile material being sprayed which is undesirable because of unwanted deposition on surfaces, among other environmental deficiencies.
There exists a need for an aqueous aerosol composition for the delivery of atomized oil such as a fragrance oil, insecticidal oil and medicinal oil without the disadvantages associated with presently available systems.
SUMMARY OF THE INVENTION
This invention is directed to an aqueous aerosol composition containing water, water soluble propellant, dispersed oil phase in the water, nonionic surfactant and a polymeric emulsifier. The components of the composition are contained in relative amounts to provide a viscosity for delivery of atomized particles of the oil.
In accordance with the principles of this invention, a water based system is used to give a concentrated aqueous system that does not need shaking, is not flammable, and performs like a concentrated non-aqueous system. This invention is predicated in part upon the use of a polymeric emulsifier that forms a matrix into which the oil can be trapped. A nonionic surfactant helps suspend the oil particles by decreasing the droplet size of the dispersed phase in the water. A water soluble propellant, such as dimethyl ether has been found to provide the composition with satisfactory delivery of atomized oil particles. The aqueous aerosol compositions of this invention have been found to provide substantial stability on standing for many months. Furthermore, atomized particles are delivered by the compositions without bearding and with a consistent spray pattern during the life of the product. In contrast to other water-based aerosol systems, the compositions of this invention do not require shaking before use, notwithstanding the unique three-phase system of the polymer matrix, oil and water. Heretofore, three-phase aerosol systems have required shaking before use. In this regard, this is considered one of the unexpected advantages of the composition of this invention.
Another advantage of the aqueous aerosol compositions of this invention is the ability to use varying amounts of oil from about 0.1% to about 30% by weight while even employing one low level of polymeric emulsifier. It has been found that a minor amount of polymeric emulsifier, on the order of about 0.05% to about 0.4% by weight, is capable of physically suspending or emulsifying significant amounts of perfume in a three dimensional matrix and holds them there in what might be considered a thermodynamically unstable form. The oil particles are surrounded by the surfactant which helps hold them in suspension. In this regard, very minor amounts of surfactant, on the order of only about 0.1% to about 1% by weight, are necessary to hold the oil particles in solution.
A water soluble propellant such as dimethyl ether and methylethyl ether is required in order to obtain the benefits of this invention. In particular, the aqueous solutions do not exhibit flame extensions, and aerosol containers using the system comply with VOC regulations (EPA regulations for Volatile Organic Compounds, Section 183(e), Clean Air Act, 40 CFR, Chapter 1, pages 48,792—48,887). Furthermore, the inventive aqueous aerosol compositions perform at least at parity to the non-aqueous aerosol systems. An amount of a hydrocarbon propellant selected from the group consisting of propane, isobutane, butane, and mixtures thereof, may be employed with the water soluble propellant. When so employed, the hydrocarbon propellant is usually contained in an amount of from about 50% to about 20% by weight of the water soluble propellant, such as dimethyl ether.
Other advantages and objectives of this invention will be further understood with reference to the following detailed description.
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Bawa Raj
Global Technology Transfer, L.L.C.
Wood Herron & Evans L.L.P.
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