HK1227292B - Sprayable composition containing zinc oxide and a fluoro-olefin propellant - Google Patents

Description

Sprayable compositions comprising zinc oxide and a fluoroolefin propellant

Related applications

This application claims priority to U.S. Provisional Patent Application Serial No. 61/939,826, filed February 14, 2014, the entire disclosure of which is incorporated herein by reference.

Background of the Invention

Many people experience skin conditions such as rashes, pressure ulcers, or wounds such as cuts or first-degree burns, which require topical application of creams or ointments to aid the healing process. Typically, these conditions are more prevalent in infants, the elderly, and the infirm. For example, infants, the elderly, and the infirm may be susceptible to developing incontinence dermatitis, which occurs when the skin is exposed to prolonged moisture, which increases the pH of the skin due to contact with urine and excrement, and causes the stratum corneum, or outermost layer of the skin, to break down. Meanwhile, pressure ulcers, also known as bedsores or decubitus ulcers, are also a concern. A pressure ulcer is a localized injury to the skin and/or deeper tissues, typically occurring over a bony protuberance due to pressure or pressure combined with shear and/or friction. The most common sites are the sacrum, coccyx, heel, or hip, but other sites such as the elbows, knees, ankles, or the back of the skull can also be affected. Pressure ulcers occur when pressure applied to soft tissue causes complete or partial obstruction of blood flow to the soft tissue. Factors that can contribute to the formation of ulcers include protein-calorie malnutrition, microclimate (moist skin from sweating or incontinence), diseases that reduce blood flow to the skin such as arteriosclerosis, or diseases that reduce sensation at the skin such as paralysis or neuropathy.

These and other skin conditions can be prevented or treated, for example, by applying zinc oxide to the affected area of the skin. Zinc oxide can help accelerate the wound healing process and can also limit the skin's exposure to excessive moisture. Therefore, one approach for treating these skin conditions is to block moisture from reaching the skin, for example by applying an oil-based protectant or cream, including various over-the-counter creams or ointments containing zinc oxide, to the affected area. However, if the skin is not completely dry, some of these oil-based protectants and creams can actually seal moisture into the skin rather than out. Furthermore, such protectants and creams are very sticky and can be greasy, making them difficult to remove from the hands after application to the affected area of the skin. In addition, rubbing these products into the skin can cause additional discomfort or pain, and if a caregiver or healthcare provider must apply the product to the patient, this can cause embarrassment for both the patient and the caregiver, depending on the location of application.

Therefore, there is a need for compositions that can provide an adequate moisture barrier without the risk of trapping moisture inside the skin, and that can be applied more easily without causing discomfort. One approach is to use a therapeutic composition together with a propellant to produce an aerosol spray composition. However, the high viscosity of the resulting aerosol spray composition means that it is often difficult to formulate the composition into a sprayable medium due to clogging problems with valves and nozzles in dispensers. In addition, many propellants have too high a vapor pressure, which can result in an unstable spray or airflow of the product that is not uniformly controlled, meaning that a smooth and even application of the aerosol spray composition to the skin area to be treated is not achievable.

Another problem associated with the aforementioned sprayable compositions is that particulate components of the sprayable composition, such as zinc oxide, often settle to the bottom of the container in which the sprayable composition is stored, resulting in settling of the composition in the container and clumping of the product. Furthermore, many sprayable compositions have a low viscosity to allow for spraying, but this results in insufficient viscosity when the composition is applied to the surface of the skin, resulting in a runny product that does not evenly coat or effectively contact the skin.

Therefore, a need exists for a sprayable zinc oxide composition comprising zinc oxide particles that remains substantially evenly distributed and can be evenly sprayed onto the skin as a fine mist.

SUMMARY OF THE INVENTION

According to one embodiment of the present invention, a sprayable zinc oxide composition is disclosed. The composition comprises a fluoroolefin propellant and zinc oxide particles.

According to another embodiment of the present invention, a method of forming a sprayable zinc oxide composition is disclosed. The method comprises forming a base zinc oxide composition, wherein the base zinc oxide composition comprises zinc oxide particles and a carrier fluid; introducing the base zinc oxide composition into a spray container; and injecting a hydrofluoroolefin propellant into the container.

According to yet another embodiment of the present invention, a method of applying a zinc oxide composition to a surface is disclosed, wherein the method comprises spraying the composition onto the surface to leave a coating thereon, wherein the composition comprises a fluoroolefin propellant and zinc oxide particles.

Other features and aspects of the present invention will be described in more detail below.

BRIEF DESCRIPTION OF THE DRAWINGS

A full and enabling disclosure of the present invention, including the best mode thereof, to those skilled in the art is more particularly set forth in the remainder of the specification with reference to the accompanying drawings, in which:

FIG1 is a cross-sectional side view of a spray delivery system according to one embodiment of the present disclosure;

2A is a front view of an actuator that may be used in a spray delivery system according to one embodiment of the present disclosure;

FIG2B is a cross-sectional side view of the actuator of FIG2A ;

FIG3 is a cross-sectional side view of a spray assembly according to one embodiment of the present disclosure; and

4 is a cross-sectional side view of a spray delivery system according to another embodiment of the present disclosure using the spray assembly of FIG. 3 .

Repeat use of reference characters in the present specification and drawings is intended to represent same or analogous features or elements of the invention.

Detailed Description of Representative Implementations

Those skilled in the art will appreciate that the current discussion is merely a description of exemplary embodiments and is not intended to limit the broader aspects of the invention.

Generally speaking, the present invention relates to a sprayable composition that can be used to treat skin conditions. The composition comprises a propellant that is particularly useful for forming a sprayable composition containing zinc oxide particles. The propellant can be, for example, a hydrofluoroolefin propellant. The inventors have discovered that by selectively controlling certain aspects of the propellant, such as specific gravity, vapor pressure, and/or molecular weight, a composition having a substantially uniform distribution of zinc oxide particles can be obtained. Furthermore, the sprayable composition can be stable such that when stored in a container at 21° C. for 3 days, less than about 3 wt.%, such as less than about 2 wt.%, such as less than about 1 wt.%, of the zinc oxide particles in the composition settles. This results in a composition that can be uniformly sprayed onto a surface as a substantially uniform coating of zinc oxide particles.

The ratio of the specific gravity of the propellant to the specific gravity of the composition can be from about 0.7 to about 1.6, such as from about 0.8 to about 1.5, such as from about 0.9 to about 1.4. Such a specific gravity ratio results in the propellant having a specific gravity similar to that of the overall composition, which means that the propellant can be substantially evenly distributed throughout the composition. Because the propellant is distributed throughout the composition in this manner, settling of the zinc oxide particles and other particulates contained in the sprayable zinc oxide composition can be avoided. Further, as measured at 21°C and based on a density of 1.0 for water at 21°C, the propellant can have a specific gravity of from about 1.03 to about 1.3, such as from about 1.05 to about 1.25, such as from about 1.07 to about 1.2. At the same time, as measured at 21°C, the sprayable zinc oxide composition can have a specific gravity of from about 0.8 to about 1.3, such as from about 0.85 to about 1.25, such as from about 0.9 to about 1.2.

In addition, the propellant can provide a sufficiently high vapor pressure for the composition so that it can be atomized and sprayed in the form of an aerosol, but the vapor pressure is not so high that the resulting spray produces excessive misting or discomfort when sprayed onto the skin, or requires a specially designed aerosol container. For example, at room temperature (21° C.), the vapor pressure can be less than about 60 psi. In some embodiments, for example, the vapor pressure can be from about 30 psi to about 60 psi, such as from about 35 psi to about 55 psi, such as from about 40 psi to about 50 psi. Without being limited by theory, it is believed that the fluoroolefin propellants of the present invention, which have a lower vapor pressure at room temperature than other propellants, can be used in larger quantities in the sprayable zinc oxide composition, which will produce a smoother, more easily controlled spray and also ensure complete evacuation of the container in which the sprayable zinc oxide composition is stored. Further, due to the low vapor pressure of the propellant, it is not necessary to use a high-pressure aerosol container as is required when using other propellants.

In addition, the molecular weight of the propellant can be greater than 100 grams per mole, such as from about 100 grams per mole to about 400 grams per mole, such as from about 105 grams per mole to about 300 grams per mole, such as from about 110 grams per mole to about 200 grams per mole. By using a propellant with a molecular weight within this range, sedimentation of the zinc oxide particles can be further prevented.

The amount of fluoroolefin propellant included in the sprayable zinc oxide composition of the present invention may be from about 5 wt.% to about 95 wt.%, based on the total weight of the composition. Meanwhile, the amount of zinc oxide particles included in the sprayable zinc oxide composition of the present invention may be from about 0.5 wt.% to about 30 wt.%, based on the total weight of the composition.

I. Sprayable Zinc Oxide Compositions

a. Propellant

The sprayable zinc oxide composition of the present invention comprises a hydrofluoroolefin propellant. The propellant can provide the energy required to aid in the delivery of the zinc oxide particles to the surface of the skin affected by a skin condition, such as a rash, ulcer, cut, or wound. In other words, the hydrofluoroolefin propellant can provide the propulsive force required to spray the zinc oxide particles onto the skin. Thus, the propellant has sufficient dispersing energy to overcome the surface tension of the liquid component of the sprayable zinc oxide composition.

In one embodiment, the propellant of the present invention comprises at least one fluoroolefin. In a specific embodiment, the propellant comprises a hydrofluoroolefin containing 3 to 4 carbon atoms, such as three carbon atoms. When the hydrofluoroolefin propellant of the present invention comprises at least one hydrogen, at least one fluorine, and no chlorine, it may be referred to as an "HFO." HFOs are derivatives of olefins. In some embodiments, the HFO propellants of the present invention may comprise two carbon-carbon double bonds.

In a specific embodiment, the sprayable zinc oxide composition of the present invention comprises a propellant represented by the following formula I:

wherein each R is independently hydrogen or a halogen, such as fluorine (F), bromine (Br), iodine (I) or chlorine (Cl), and preferably fluorine (F),

R' is (CR ₂ ) _n Y,

Y is CRF ₂ , and

n is 0 or 1.

Further, in a specific embodiment, Y is CF ₃ , n is 0, and at least one of the remaining R groups is F. In another specific embodiment, Y is CF ₃ , at least one R on the unsaturated terminal carbon is H, and at least one of the remaining R groups is F. In yet another embodiment, the fluoroolefin propellants of the present invention may contain one or more tetrafluoropropenes, and such propellants may be referred to herein as HFO-1234 propellants. Examples of tetrafluoropropenes contemplated by the present invention are HFO-1234yf (specific gravity at 21° C. of 1.092) and HFO-1234ze (specific gravity at 21° C. of 1.17) in cis and/or trans form. It is understood that HFO-1234ze refers to 1,1,1,3-tetrafluoropropene, whether in the cis- or trans-form, and the terms "cisHFO-1234ze" and "transHFO-1234ze" are used herein to describe the cis and trans forms, respectively, of 1,1,1,3-tetrafluoropropene.

In some embodiments, HFO-1234ze may comprise a combination of trans-HFO-1234ze and cis-HFO-1234ze, such as from about 90% to about 99% of the trans isomer based on the total HFO-1234ze, and from about 1% to about 10% of the cis isomer on the same basis. Thus, in some embodiments, the propellants of the present invention may comprise a combination of cis-HFO-1234ze and trans-HFO-1234ze, preferably in a cis to trans weight ratio of from about 1:99 to about 10:99, such as from about 1:99 to about 5:95, such as from about 1:99 to about 3:97.

Although the properties of cis-HFO-1234ze and trans-HFO-1234ze differ in at least some respects, it is expected that each of these compounds is suitable for use as a propellant in the sprayable zinc oxide composition of the present invention, either alone or in combination with other compounds (including stereoisomers thereof). For example, although trans-HFO-1234ze has a relatively low boiling point (-19° C.), it is expected that cis-HFO-1234ze, which has a boiling point of 9° C., can also be used as a propellant in the sprayable zinc oxide composition of the present invention. Further, it should be understood that the terms HFO-1234ze and 1,1,1,3-tetrafluoropropene both refer to stereoisomers, and the use of these terms covers both cis- and trans-forms.

The fluoroolefin propellant may be included in the sprayable zinc oxide composition of the present invention in an amount of about 5 wt.% to about 95 wt.%, such as 10 wt.% to about 80 wt.%, such as about 15 wt.% to about 60 wt.%, based on the total weight of the composition.

b. Zinc oxide particles

Additional components that may be present in the sprayable zinc oxide composition will now be discussed in greater detail. First, the sprayable zinc oxide composition of the present invention further comprises zinc oxide particles, which repel moisture and create a barrier between the skin and the environment to protect the skin from excess moisture. The zinc oxide particles may have an average particle size of about 20 nanometers to about 200 nanometers, such as about 25 nanometers to about 150 nanometers, such as about 30 nanometers to about 100 nanometers.

The zinc oxide particles can be hydrophobic, for example, by applying a hydrophobic coating on the surface of the zinc oxide particles, as described in more detail below. The particles can also carry an inorganic coating, independently or in combination with the hydrophobic coating, as described in more detail below. The zinc oxide particles can be coated with aluminum oxide, silicon dioxide, an organic material, a polysiloxane, or a combination thereof. Other suitable surface treatments may include: phosphates (including lecithin), perfluoroalkyl alcohol phosphates, fluorosilanes, isopropyl titanium triisostearate, stearic acid or other fatty acids, silanes, dimethicone, and related polysiloxane polymers, or a combination thereof.

For example, the zinc oxide particles may be coated with oxides of other elements, such as oxides of aluminum, zirconium or silicon, or mixtures thereof, such as aluminum oxide and silicon dioxide. Alternatively, the zinc oxide particles may be treated with boron nitride or other known inorganic coatings, alone or in combination, before being embedded in the pores of the microparticles. The inorganic coating may be applied using techniques known in the art. A typical method may involve forming an aqueous dispersion of zinc oxide particles in the presence of a soluble salt of an inorganic element, the oxide of which will form the coating. The dispersion is typically acidic or alkaline, depending on the nature of the salt selected, and precipitation of the inorganic oxide is obtained by adjusting the pH of the dispersion by adding an acid or base, as appropriate. The inorganic coating, if present, may be applied as a first layer to the surface of the zinc oxide particles.

In another embodiment, the zinc oxide particles can include an organic coating that provides hydrophobicity. The organic coating can be applied to the inorganic coating (if present), or directly applied to the zinc oxide. The hydrophobic coating agent can be, for example, a polysiloxane, a silane, a metal soap, a titanate, an organic wax, or a combination thereof. Alternatively, the hydrophobic coating can include a fatty acid, for example, a fatty acid containing 10 to 20 carbon atoms, such as lauric acid, stearic acid, isostearic acid, and salts of these fatty acids. The fatty acid can be isopropyl titanium triisostearate. For polysiloxanes, the hydrophobic coating can be polymethylsiloxane, dimethicone, a copolymer thereof, or a mixture thereof. The polysiloxane may also be an organosilicon compound, such as dimethylpolysiloxane ("Me" is methyl, _CH3 ) having a repeating _-Me2SiO- unit backbone, methylhydrogenpolysiloxane having a repeating -MeHSiO- unit backbone, and alkoxysilane of the formula _{RnOSiH (4-n)} , where "R" is an alkyl group and "n" is an integer of 1, 2, or 3. Regarding silanes, the hydrophobic coating agent may be an alkoxysilane, such as an alkyltriethoxy or alkyltrimethoxysilane available from OSI Specialties or PCR. The alkoxysilane may be triethoxycaprylylsilane or perfluoroalkylethyltriethoxysilane having a _C3 to _C12 alkyl group, which may be linear or branched. Zinc oxide particles coated with triethoxycaprylylsilane are commercially available from UmicoreZinc Chemicals under the name ZANO ^™ 10 Plus.

The zinc oxide particles may be included in the sprayable zinc oxide composition of the present invention in an amount of about 0.5 wt.% to about 30 wt.%, such as 1 wt.% to about 25 wt.%, such as about 2 wt.% to about 20 wt.%, based on the total weight of the sprayable zinc oxide composition.

c. Carrier fluid

The propellant and zinc oxide particles can each be substantially uniformly distributed in the carrier fluid as part of a solution or as a component of a colloidal suspension or dispersion. For example, the propellant, zinc oxide particles, and carrier fluid can form a water-in-oil emulsion or an oil-in-water emulsion. However, it is also understood that the carrier fluid can be oil or water.

The applicable oil that can use in the carrier fluid comprises mineral oil, vegetable oil, silicone oil or its combination.As liquid petroleum derivatives that can be used according to the present invention, the example of commercially available mineral oil can comprise WitcoCorporation's CARNATION ^™ mineral oil or Penreco Corporation's DRAKEOL ^™ mineral oil.Operable suitable vegetable oil is the oil derived from non-petroleum biomass, comprises plant or fruit oil, as almond oil (almond oil), peanut oil, wheat germ oil, linseed oil, jojoba oil, apricot kernel oil, walnut oil, palm fruit oil, pistachio oil, sesame seed oil, rapeseed oil, juniper oil, corn oil, peach kernel oil, poppy oil, pine oil, castor oil, soybean oil, avocado oil, safflower oil, coconut oil, hazelnut oil, olive oil, grape seed oil, sunflower oil, apricot kernel oil, geranium oil, rice bran oil and composition thereof.Operable silicone oil comprises disiloxane, cyclomethicone, dimethicone and derivative thereof and polydimethylsiloxane fluid. Cyclomethicone is a volatile compound and evaporates when applied to the surface of the skin, so that the resulting coating is dry to the touch. Other similar volatile compounds that can be used include isododecane.

Water may also be used as a carrier fluid alone or in combination with any of the oils mentioned above as part of a water-in-oil emulsion or an oil-in-water emulsion.

When using oil and water simultaneously, the oil can be present in the composition in an amount of about 1wt.% to about 35wt.%, such as about 3wt.% to about 30wt.%, such as about 5wt.% to about 25wt.%. Meanwhile, the water can be present in an amount of less than about 50wt.%, such as about 1wt.% to about 50wt.%, such as about 5wt.% to about 45wt.%, such as about 10wt.% to about 40wt.%, based on the total weight of the composition. Further, in some embodiments, it should be understood that the water exists in an amount of less than 30wt.% based on the total weight of the composition.

Regardless of the specific carrier fluid or combination of carrier fluids used, the total amount of carrier fluid or multiple carrier fluids present in the composition is from about 10 wt.% to about 70 wt.%, such as from about 15 wt.% to about 65 wt.%, such as from about 20 wt.% to about 60 wt.%, based on the total weight of the composition.

d. Emulsifier

The sprayable zinc oxide composition may also include one or more emulsifiers as part of an emulsifier system to help establish a stable, substantially homogeneous, uniform dispersion of the propellant and the zinc oxide particles by preventing the sprayable zinc oxide composition from separating into constituent phases. The emulsifier system may also include one or more nonionic, anionic, and/or amphoteric emulsifiers, including mixtures of different species or mixtures of different surfactants within the same species.

Nonionic surfactants, which typically have a hydrophobic group (such as a long chain alkyl or alkylated aryl group) and a hydrophilic chain (such as a chain containing ethoxy and/or propoxy moieties), may be particularly suitable. Some suitable nonionic surfactants that may be used include, but are not limited to, ethoxylated alkylphenols, ethoxylated and propoxylated fatty alcohols, polyethylene glycol ethers of methyl glucose, polyethylene glycol ethers of sorbitol, ethylene oxide-propylene oxide block copolymers, ethoxylated esters of fatty acids ( _C8 - _C18 ), condensation products of ethylene oxide with long chain amines or amides, condensation products of ethylene oxide with alcohols, fatty acid esters, mono- or diglycerides of long chain alcohols, and mixtures thereof. Particularly suitable nonionic emulsifiers may include ethylene oxide condensates of fatty alcohols (e.g., sold under the trade name Lubrol), polyoxyethylene ethers of fatty acids (particularly _C12 - _C20 fatty acids), polyoxyethylene sorbitan fatty acid esters (such as sold under the trade name sorbitan), and sorbitan fatty acid esters (such as sold under the trade name SPAN ^™ or sorbitan). The fatty acid component used to form such emulsifiers may be saturated or unsaturated, substituted or unsubstituted, and may contain 6 to 22 carbon atoms, in some embodiments 8 to 18 carbon atoms, and in some embodiments 12 to 14 carbon atoms.

While any emulsifier can generally be used, the present inventors have discovered that certain combinations of hydrophilic and lipophilic nonionic emulsifiers are particularly effective in stabilizing the emulsion. As is known in the art, the relative hydrophilicity or lipophilicity of an emulsifier can be characterized by the hydrophilic/lipophilic balance ("HLB") scale, which measures the balance between the hydrophilicity and lipophilic solution tendencies of a compound. The HLB scale ranges from 0.5 to about 20, with smaller numbers indicating a high lipophilic tendency and higher numbers indicating a high hydrophilic tendency. Desirably, the emulsions of the present invention may comprise at least one "hydrophilic" emulsifier having an HLB value of from about 10 to about 20, in some embodiments from about 12 to about 19, and in some embodiments, from about 14 to about 18. Likewise, the emulsions may also comprise at least one "lipophilic" emulsifier having an HLB value of from about 0.5 to about 10, in some embodiments from about 1 to about 9, and in some embodiments, from about 2 to about 8. If desired, two or more surfactants may be used that have HLB values above or below the desired value, but together have an average HLB value within the desired range. Regardless, the inventors have discovered that the weight ratio of the lipophilic emulsifier to the hydrophilic emulsifier in the sprayable zinc oxide composition is typically in the range of about 5 to about 30, in some embodiments, about 7.5 to about 25, and in some embodiments, about 10 to about 20. Further, the inventors have discovered that the overall HLB value of the sprayable zinc oxide composition is typically lipophilic and ranges from about 3 to about 10, such as from about 4 to about 9, such as from about 5 to about 8.

One particularly useful group of "lipophilic" emulsifiers are sorbitan fatty acid esters (e.g., monoesters, diesters, triesters, etc.), which are prepared by dehydrating sorbitol to yield 1,4-sorbitan, which is then reacted with one or more equivalents of a fatty acid. The fatty acid-substituted portion can be further reacted with ethylene oxide to yield a second group of surfactants. The fatty acid-substituted sorbitan surfactants are prepared by reacting 1,4-sorbitan with a fatty acid such as lauric acid, palmitic acid, stearic acid, oleic acid, or a similar long-chain fatty acid to produce 1,4-sorbitan monoester, 1,4-sorbitan sesquioleate, or 1,4-sorbitan triester. Common names for these surfactants include, for example, sorbitan monolaurate, sorbitan monopalmitate, sorbitan monostearate, sorbitan monooleate, sorbitan sesquioleate, and sorbitan trioleate. Such surfactants are commercially available under the names SPAN ^™ or ARLACEL ^™ , typically with letter or numeric designations distinguishing the various mono-, di-, and triester-substituted sorbitans. SPAN ^™ and ARLACEL ^™ surfactants are lipophilic and generally soluble or dispersible in oils, but generally not soluble in water. A particularly suitable surfactant is sorbitan monooleate, which is commercially available as SPAN ^™ 80. Typically these surfactants will have an HLB value in the range of 1.8 to 8.6.

Other useful lipophilic emulsifiers that can be used include, for example, silicone water-in-oil emulsifiers. Silicone refers to a molecule that contains at least one siloxane (—Si—O—) repeating unit and additionally contains a hydrophobic portion and a hydrophilic portion. The HLB value of silicone water-in-oil emulsifiers is relatively low. For example, in some embodiments, the silicone emulsifier can have an HLB value in the range of 2 to 9.

Examples of suitable silicone water-in-oil emulsifiers can include non-crosslinked dimethicone copolyols such as alkoxy dimethicone copolyols, silicones with pendant hydrophilic moieties such as linear polysiloxanes with polyether side groups, branched polyether and alkyl-modified polysiloxanes, branched glycerin polymers and alkyl-modified polysiloxanes, and combinations thereof. Examples of commercially available non-crosslinked dimethicone copolyols include the following from Dow Corning of Midland, Michigan: cyclopentasiloxane and PEG/PPG-18/18 dimethicone available as DC 5225C, and cyclopentasiloxane and PEG-12 dimethicone crosspolymer available as DC 9011. Some non-crosslinked dimethicone copolyols are cetyl dimethicone copolyol such as cetyl PEG/PPG-10/1 dimethicone sold under the name ABIL ^™ EM-90, branched polyether and alkyl-modified polysiloxanes such as lauryl PEG-9 polydimethylsiloxyethyl dimethicone sold under the name KF-6038, and branched glycerin polymers and alkyl-modified silicones such as lauryl polyglyceryl-3 polydimethylsiloxyethyl dimethicone sold under the name KF-6105. Other non-crosslinked dimethicone copolyols include, for example, bis-PEG/PPG-14/dimethicone copolyol sold under the name ABIL ^™ EM-97, and the polyglyceryl-4 isostearate/cetyl dimethicone copolyol/hexyl laurate mixture sold under the name ABIL ^™ WE 09. ABIL ^™ EM-90, ABIL ^™ EM-97, and ABIL ^™ WE 09 are available from Evonik Goldschmidt GmbH in Essen, Germany. KF-6038 and KF-6105 are available from Shin-Etsu Silicones in Akron, Ohio. A particularly suitable emulsifier for use in the present invention is ABIL ^™ WE 09, which has an HLB value of about 5. Another particularly suitable emulsifier is ABIL ^™ EM 90, which also has an HLB value of about 5.

Yet another suitable nonionic lipophilic emulsifier that may be included in the sprayable zinc oxide composition of the present invention is octyldodecanol/octyldodecanol xyloside/PEG-30, which is commercially available from Seppic S.A. under the name EASYNOV ^™ .

Meanwhile, sorbitan fatty acid esters (such as monoesters, diesters, triesters, etc.) that have been modified with polyethylene glycol are also a group of particularly useful "hydrophilic" emulsifiers. These materials are typically prepared by adding ethylene oxide to 1,4-sorbitan esters. The addition of polyethylene glycol converts the lipophilic sorbitan ester surfactant into a hydrophilic surfactant, which is generally soluble or dispersible in water. Such materials are commercially available under the name TWEEN ^™ (such as TWEEN ^™ 80, polysorbate 80, or polyethylene (20) sorbitan monooleate). TWEEN ^™ surfactants typically have an HLB value in the range of 9.6 to 16.7. For example, TWEEN ^™ 80 has an HLB value of 15. Still other suitable hydrophilic emulsifiers may include sucrose fatty acid esters such as sucrose monopalmitate (HLB 15) and sucrose monostearate (HLB 11) or PEG-32 glyceryl laurate (HLB 14) and the BRIJ ^™ family of polyethylene glycol (PEG) n-alkyl esters such as BRIJ ^™ 35, 56, 58, 76, 78 and 99, which have an HLB range of 12.4 to 16.9. BRIJ ^™ 56 is polyethylene glycol [10] cetyl ether, for example, having an HLB value of 12.9.

Regardless of the specific emulsifier used, the amount of emulsifier that can be present in the sprayable zinc oxide composition is from about 0.1 wt.% to about 20 wt.%, such as from about 0.5 wt.% to about 15 wt.%, such as from about 1 wt.% to about 10 wt.%, based on the total weight of the sprayable zinc oxide composition. Further, the inventors have found that the weight ratio of the lipophilic emulsifier to the hydrophilic emulsifier in the sprayable zinc oxide composition is typically in the range of about 5 to about 30, in some embodiments, from about 7.5 to about 25, and in some embodiments, from about 10 to about 20.

e. Viscosity modifier

In addition, the composition may include one or more viscosity modifiers, which may also help prevent the separation of the various components of the composition. For example, in some embodiments, such as when the carrier fluid contains more than one component, one or more viscosity modifiers may be added to the oil phase or the water phase of the emulsion to adjust the viscosity so that the separated components in the composition are more miscible. Further, the viscosity of the overall composition may be adjusted so that it is not so high that the composition cannot be sprayed onto a surface, but also not so low that the composition is too dilute to be evenly applied to the surface. Thus, the composition may have a viscosity greater than about 1000 centipoise, such as from about 1000 centipoise to about 8000 centipoise, such as from about 1500 centipoise to about 6000 centipoise, such as from about 2000 centipoise to about 4000 centipoise.

When a water-in-oil emulsion or an oil-in-water emulsion is used in the sprayable zinc oxide composition, one or more viscosity modifiers may be added to the aqueous phase of the water-in-oil emulsion or the oil-in-water emulsion to enhance the miscibility between the aqueous and oil phases, which promotes substantially uniform distribution of the components of the sprayable zinc oxide composition. However, it should also be understood that viscosity modifiers may be added to an already formed oil-in-water or water-in-oil emulsion to adjust the viscosity as needed.

Suitable viscosity modifiers include carboxylic acid polymers, which are cross-linked compounds comprising one or more monomers derived from acrylic acid, substituted acrylic acids, and salts and derivatives of these acrylic acids and substituted acrylic acids. They can be cross-linked homopolymers of acrylic acid or its derivatives, such as acrylamidopropanesulfonic acid. They can also be cross-linked copolymers comprising: (i) a first monomer selected from (meth)acrylic acid, its derivatives, short-chain (i.e., _C1 - _C4 ) acrylate monomers, and mixtures thereof; and (ii) a second monomer that is a long-chain (i.e., _C8 - _C40 ) substituted polyethylene glycol acrylate monomer.

Examples of commercially available carboxylic acid polymers include CARBOPOL ^™ 1342, PEMULEN ^™ TR-1, and PEMULEN ^™ TR-2, available from Lubrizol Corp.; Sepigel 305, SIMULGEL ^™ EG, SIMULGEL ^™ NS, and SIMULGEL ^™ 600, available from Seppic SA; and VISCOLAM ^™ AT100P and VISCOLAM ^™ AT64/P, available from Lamberti SpA. A commercially available viscosity modifier is available from Seppic SA as SIMULGEL ^™ NS. SIMULGEL ^™ NS contains hydroxyethyl acrylate/sodium acryloyldimethyl taurate copolymer, squalane, and polysorbate 60, which can be added to the oil phase of a water-in-oil or oil-in-water emulsion.

Other suitable viscosity modifiers that can be used include corn starch (topical starch), talc, rice starch, oat starch, tapioca starch, potato starch, bean starch, soy starch, radish starch, microcrystalline cellulose, kaolin, aluminum starch octenylsuccinate, and mixtures thereof. Water-soluble aluminum starch octenylsuccinates are commercially available from National Starch & Chemical Co. as DRY FLO ^™ Pure, DRY FLO ^™ XT, DRY FLO ^™ PC, and/or DRY FLO ^™ AF (aluminum-free grades) and are water-soluble so that they can be included in the aqueous phase of a water-in-oil emulsion or an oil-in-water emulsion.

Regardless of the specific viscosity modifier used, the viscosity modifier can be present in the sprayable zinc oxide composition in an amount ranging from about 0.05 wt.% to about 15 wt.%, such as from about 0.1 wt.% to about 10 wt.%, such as from about 0.5 wt.% to about 5 wt.%, based on the total weight of the sprayable zinc oxide composition.

f. Additional moisture barrier/waterproof material

The sprayable zinc oxide composition may also include other moisture barriers or waterproofing materials in addition to the zinc oxide particles discussed above. For example, the sprayable zinc oxide composition may include paraffin wax, microcrystalline wax, petrolatum, beeswax, or a combination thereof. Such moisture barriers may be present in the sprayable zinc oxide composition in an amount of from about 0.1 wt.% to about 6 wt.%, such as from about 0.25 wt.% to about 4 wt.%, such as from about 0.5 wt.% to about 2 wt.%, based on the total weight of the composition.

g. Conditioning agent

The sprayable zinc oxide composition can also include one or more conditioning agents to help condition the skin. For example, the composition can include thymol iodine, sodium chloride, magnesium chloride, magnesium sulfate, lanolin, lanolin oil, lanolin wax, lanolin alcohol, lanolin acid, isopropyl lanolin, ethoxylated lanolin, ethoxylated lanolin alcohol, ethoxylated cholesterol, propoxylated lanolin alcohol, acetylated lanolin alcohol, lanolin alcohol linoleate, lanolin alcohol ricinoleate, acetic acid esters of lanolin alcohol, ricinoleate, acetic acid esters of ethoxylated alcohol esters, hydrogenolysis products of lanolin, ethoxylated hydrogenated lanolin, ethoxylated sorbitol lanolin, or a combination thereof. Thymol iodine and magnesium sulfate can be particularly useful. One or more conditioning agents can be present in the sprayable zinc oxide composition in an amount of about 0.05 wt.% to about 10 wt.%, such as about 0.1 wt.% to about 7.5 wt.%, such as about 0.5 wt.% to about 5 wt.%, based on the total weight of the composition.

h. Additional components

Other optional components in the sprayable zinc oxide composition can include skin care additives such as emollients, fragrances, and preservatives. For example, an emollient such as caprylic/capric triglyceride can be included in the sprayable zinc oxide composition. Other suitable emollients include stearoxytrimethylsilane, hexadecyl lactate, and alkyl lactates, such as C ₁₂ -C _{15 alkyl lactates. When an emollient is used, the sprayable zinc oxide composition can have a smooth feel when applied to the skin. One or more emollients can be present in the sprayable zinc oxide composition in an amount of about 0.1 wt.% to about 25} wt.%, such as about 0.5 wt.% to about 20 wt.%, such as about 1 wt.% to about 15 wt.%, based on the total weight of the composition.

Further, the fragrance can be present in the sprayable zinc oxide composition in an amount of about 0.005 wt.% to about 2 wt.%, such as about 0.01 wt.% to about 1.5 wt.%, such as about 0.02 wt.% to about 1 wt.%, based on the total weight of the composition.

Meanwhile, the preservative can be present in the composition in an amount of about 0.01 wt.% to about 6 wt.%, such as about 0.02 wt.% to about 4 wt.%, such as about 0.05 wt.% to about 1 wt.%, based on the total weight of the composition. Suitable preservatives include paraben-based preservatives, such as methylparaben and propylparaben.

Furthermore, the present inventors have discovered that antifreeze agents can be included in the composition to limit the amount of crystallization of any solid components, which can then reduce or limit clogging when the composition is sprayed. If desired, one or more antifreeze agents can be used, such as glycols (e.g., ethylene glycol, propylene glycol, butylene glycol, triethylene glycol, hexylene glycol, polyethylene glycol, ethoxydiglycol, dipropylene glycol, etc.); glycol ethers (e.g., methyl glycol ether, ethyl glycol ether, isopropyl glycol ether, etc.); and the like. Such antifreeze agents can be present in the composition in an amount of about 0.1 wt.% to about 15 wt.%, such as about 0.5 wt.% to about 10 wt.%, such as about 1 wt.% to about 5 wt.%, based on the total weight of the composition.

II. Formation of Sprayable Zinc Oxide Compositions

Generally, the sprayable zinc oxide composition of the present invention can be prepared by forming a base zinc oxide composition from a carrier fluid and zinc oxide particles, introducing the base zinc oxide composition into a spray container, and injecting a propellant, such as a hydrofluoroolefin propellant, into the container. For example, when the base zinc oxide composition is in the form of a water-in-oil emulsion or an oil-in-water emulsion, the base zinc oxide composition can be prepared by first separately forming an oil phase and an aqueous phase.

It is well known to those skilled in the art that the mode that water-in-oil emulsion or oil-in-water emulsion forms can change.In one embodiment, for example, oil can be initially blended with optional emulsifier, emollient, conditioner etc. to form the oil phase.In such embodiment, the oil phase can comprise the oil of the amount of about 30wt.% to about 80wt.%, such as about 35wt.% to about 70wt.%, such as about 40wt.% to about 60wt.% based on the gross weight of the oil phase. Further, the oil phase can comprise the emulsifier of the amount of about 5wt.% to about 35wt.%, such as about 10wt.% to about 30wt.%, such as about 15wt.% to about 25wt.% based on the gross weight of the oil phase.The addition of the emulsifier can cause the oil phase to have an HLB value of about 6 to about 7. In addition, the oil phase may comprise an emollient in an amount of from about 10 wt.% to about 45 wt.%, such as from about 15 wt.% to about 40 wt.%, such as from about 20 wt.% to about 35 wt.%, based on the total weight of the oil phase. In addition, the oil phase may comprise a conditioning agent in an amount of from about 0.5 wt.% to about 10 wt.%, such as from about 1 wt.% to about 7.5 wt.%, such as from about 1.5 wt.% to about 5 wt.%, based on the total weight of the oil phase.

Meanwhile, the aqueous phase can be formed by blending water with other components such as conditioners, viscosity modifiers, and the like. In such an embodiment, the aqueous phase can comprise water in an amount of about 50 wt.% to about 99 wt.%, such as about 55 wt.% to about 98 wt.%, such as about 60 wt.% to about 97 wt.%. The aqueous phase can also comprise a conditioner in an amount of about 0.5 wt.% to about 15 wt.%, such as about 1 wt.% to about 10 wt.%, such as about 1.5 wt.% to about 7.5 wt.%, based on the total weight of the aqueous phase. In addition, the aqueous phase can comprise a viscosity modifier in an amount of about 0.25 wt.% to about 10 wt.%, such as about 0.5 wt.% to about 7.5 wt.%, such as about 1 wt.% to about 5 wt.%, based on the total weight of the aqueous phase.

After the oil phase and the aqueous phase are formed separately, the aqueous phase can be added to the oil phase to form a water-in-oil emulsion. The combination of the phases can be promoted by agitation (such as stirring) and controlling the temperature of each mixture. Then, zinc oxide particles can be added to the water-in-oil emulsion. The zinc oxide particles can be present in the water-in-oil emulsion in an amount of about 0.25wt.% to about 35wt.%, such as about 0.5wt.% to about 30wt.%, such as about 1wt.% to about 25wt.%, such as about 5wt.% to about 15wt.%, based on the total weight of the basic zinc oxide composition. Then, if desired, other components such as fragrances, preservatives, antifreeze agents and additional viscosity modifiers can be added to the emulsion. The fragrance can be added in an amount of about 0.01wt.% to about 5wt.%, such as about 0.05wt.% to about 2.5wt.%, such as about 0.1wt.% to about 1wt.%, based on the total weight of the basic zinc oxide composition. Similarly, the preservative may be added in an amount of about 0.01 wt.% to about 5 wt.%, such as about 0.05 wt.% to about 2.5 wt.%, such as about 0.1 wt.% to about 1 wt.%, based on the total weight of the base zinc oxide composition. Furthermore, the antifreeze agent may be added in an amount of about 0.5 wt.% to about 15 wt.%, such as about 1 wt.% to about 10 wt.%, such as about 2 wt.% to about 8 wt.%, based on the total weight of the base zinc oxide composition. Furthermore, the viscosity modifier may be added in an amount of about 0.1 wt.% to about 15 wt.%, such as about 0.5 wt.% to about 10 wt.%, such as about 1 wt.% to about 8 wt.%, based on the total weight of the base zinc oxide composition. Thus, it should be understood that in some embodiments, a first viscosity modifier may be added during the formation of the aqueous phase, while a second viscosity modifier may be added after the emulsion is formed by combining water and oil to form the base zinc oxide composition.

Regardless of the phase formed, the temperature is from about 15°C to about 40°C, such as from about 18°C to about 35°C, such as from about 20°C to about 30°C. After the individual phases are mixed as described above, the resulting base zinc oxide composition can then be filled into a spray container, such as an aerosol spray container. The propellant can then be introduced into the container, such as through a valve, and the container can be sealed. The container can be filled with the propellant at a pressure of from about 130 psi to about 230 psi, such as from about 140 psi to about 220 psi, such as from about 150 psi to about 210 psi.

III. Spray Delivery System

Various aerosol spray containers can be used in conjunction with a sprayable zinc oxide composition to form a system for spraying the composition onto a surface, such as the skin. One embodiment of a spray delivery system contemplated by the present invention is described with reference to FIG1 . The spray delivery system 100 may include a spray container 101 formed of metal or reinforced plastic. The spray container 101 has an upper opening in which a spray head 102 is mounted. The spray head 102 is mounted to the spray container 101 in such a manner that a flange 104 of the spray head is connected to a hoop 103 formed around the edge of the upper opening in the spray container 101 by welding or other possible connection methods. This creates a sealed connection between the spray head 102 and the spray container 101.

The spray head 102 is provided with a valve 105 retained by a flange 104. In its normal state, the valve 105 is held closed by the energizing force provided by a spring 106, but opens when the spray head 102 is pressed. The spray head 102 also has a nozzle 107, which communicates with the valve 105 through a conduit 108. Simultaneously, a suction tube 109 is connected to the valve 105 and extends to the bottom of the spray container 101. By pressing the spray head 102 downward against the spring 106, the valve 105 opens to form a fluid passage from the lower end of the suction tube 109 to the nozzle 107 through the valve 105 and the conduit 108.

The sprayable zinc oxide composition 110 as discussed above can be filled into the spray container 101. Then, by depressing the spray head 102, the sprayable zinc oxide composition is expelled from the nozzle 107 through the above-mentioned fluid passage in the form of a fine mist by the pressure associated with the propellant, which is substantially evenly distributed in the sprayable zinc oxide composition 110.

Another embodiment of a spray delivery system is described with reference to Figures 2A, 2B, 3 and 4. Due to the use of zinc oxide particles, it is possible that the sprayable zinc oxide composition may clog some spray delivery systems. For example, standard aerosol spray delivery systems typically use actuators (spray buttons) that are not intended to deliver compositions containing high concentrations of particulate material, such as the zinc oxide particles of the present invention. Such actuators typically use mechanical break-up inserts to finely atomize sprayable compositions containing low levels of particulates. For example, the actuator may include small channels to induce a swirl effect, producing a fine mist spray. However, when using a sprayable composition containing a higher amount of particulate material, the particulate material, such as zinc oxide particles or any other active agent particles, may clog the actuator and prevent a smooth spray from the container. Therefore, the spray delivery system of the present invention represented by Figures 2A, 2B, 3 and 4 does not include the above-mentioned actuator channels and does not have a mechanical break-up insert. Instead, the spray delivery system uses a valve and valve stem system, wherein the valve stem design allows the valve stem inside the valve to automatically wipe when the valve sprays, which prevents solids from accumulating inside the valve, thereby reducing the risk of clogging. In addition, the valve includes a valve orifice having a sufficiently large diameter so that the zinc oxide particles and other particulates of the sprayable zinc oxide composition are not blocked inside the container and a smooth mist can be achieved. Further, the valve includes an air hole to allow for enhanced mixing of the propellant vapor during spraying and prevent the accumulation of particulates inside the valve. Increasing the air hole also results in a more uniform delivery of the sprayable composition from the delivery system. The air hole also allows for an increased weight percentage of the propellant used, which helps to produce a drier, less runny product when delivered to the surface of the skin. Further, the air hole produces a spray that feels warmer because it helps to volatilize the propellant and solvent before the composition reaches the surface of the skin.

The spray system is discussed in more detail below with reference to Figures 2A, 2B, 3, and 4. Figure 2A shows a front view of a non-mechanically disruptive actuator 200 that can be used in a spray delivery system according to one embodiment of the present disclosure. Actuator 200 is a component that can be used to depress a valve stem component of a valve assembly to initiate the introduction of a sprayable zinc oxide composition, as discussed in more detail below with reference to Figures 3 and 4. Actuator 200 includes a locking ring 201, an insert 202, and a dome cap 203. Locking ring 201 prevents the actuator from being inadvertently depressed. Actuator dome cap 203 can contain insert 202, and insert 202 can determine the spray characteristics of the sprayable zinc oxide composition. Insert 202 of Figures 2A and 2B is a non-mechanically disruptive insert. Insert 202 defines an opening 204 through which the sprayable zinc oxide composition of the present invention can exit the actuator, and this opening is hereinafter referred to as the actuator orifice or outlet orifice 204. The outlet orifice 204 can have a diameter selected based on the particle size of the particulate components of the sprayable zinc oxide composition, such that the particles and other components of the sprayable zinc oxide composition can be sprayed from the outlet orifice 204 without causing clogging of the spray delivery system. Furthermore, by selectively controlling the diameter of the outlet orifice 204, the size of the resulting spray pattern can also be influenced. For example, a diameter that is too small can produce a very narrow spray pattern, while a diameter that is too large can produce a spray pattern that is too wide, resulting in excessive spray entering the surrounding environment rather than onto the intended surfaces, such as clothing, bedding, etc. For example, the outlet orifice 204 can have a diameter of about 0.3 mm to about 0.6 mm, such as about 0.35 mm to about 0.55 mm, or about 0.4 mm to about 0.5 mm. FIG2B is a cross-sectional side view of the actuator of FIG2A , showing the arrangement of the outlet orifice 204 relative to the insert 202 located within the dome cover 203. The outlet orifice is connected to the valve stem 302 of the valve assembly via an exit path 205, which will be discussed in more detail in FIG3 .

Turning now to Figures 3 and 4, cross-sectional side views of a spray delivery system are shown that includes a spray valve assembly 300 and a mounting cup 301 for use with the actuator 200 of Figures 2A and 2B. The actuator 200 is connected to the valve assembly 300 via an exit path 205 as shown in Figure 2B. The spray valve assembly 300 includes a housing or body 305 that houses a valve stem 302, a valve stem washer 304, and a spring 307. A suction tube 311 is also connected to the housing 305 via a tailpiece 309. The mounting cup 301 holds the spray valve assembly 300 together and crimps onto the container 401 to provide a seal. Generally speaking, when the actuator 203 (see Figures 2A and 2B) disposed above the mounting cup 301 is pressed against the spring 307, the valve stem 302 of the valve assembly 300 moves downward, opening the seal between the valve stem gasket 303 and the valve stem 302, allowing the valve stem hole 303 in the valve stem 302 to pass below the valve stem gasket 304. This causes the propellant component of the sprayable zinc oxide composition to force the base zinc oxide composition up the straw 311, through the tailpiece hole 310, and into the valve body 305. The air hole 306 formed in the valve body 305 provides additional propellant to the valve body 305 and helps mix the liquid base zinc oxide composition and the propellant in the valve body 305, which can produce a more uniform distribution and reduce the risk of any particles, such as zinc oxide particles, blocking the valve body 305. Since the steam pushes the base zinc oxide composition downward, the air hole 306 also keeps the base zinc oxide composition outside the valve body 305 when at rest and serves to prevent product settling. Once the sprayable zinc oxide composition (ie, substantially uniformly blended propellant and base zinc oxide composition) reaches the valve stem through valve stem aperture 303 , it passes through exit path 205 and exits outlet aperture 204 as a fine mist that does not clog the spray delivery system 400 .

The dimensions of the various components can be selected to further reduce the risk of clogging. For example, the valve stem 302 can have a diameter of about 3 mm to about 5.5 mm, such as about 3.5 mm to about 5 mm, or about 4 mm to about 4.5 mm. Meanwhile, the valve stem hole 303 can have a diameter of about 0.5 mm to about 0.75 mm, such as about 0.55 mm to about 0.7 mm, or about 0.6 mm to about 0.65 mm. Furthermore, the tail pipe hole 310 can have a diameter of about 0.75 mm to about 2 mm, such as about 1 mm to about 1.75 mm, or about 1.25 mm to about 1.5 mm. Furthermore, the air hole 306 can have a diameter of about 0.1 mm to about 0.5 mm, such as about 0.15 mm to about 0.45 mm, or about 0.2 mm to about 0.4 mm. By selectively controlling the aforementioned sizes, the propellant of the sprayable zinc oxide composition can remain substantially evenly distributed throughout the base zinc oxide composition to reduce settling of the zinc oxide particles, and the sprayable zinc oxide composition can exit the outlet orifice 204 as a fine mist with less flyaway and more even distribution than, for example, using an actuator.

IV. Application of Sprayable Zinc Oxide Compositions

As a result of the combination of the type of spray delivery system used and the properties of the sprayable composition, a substantially uniform coating of the composition can be applied to the surface. For example, the composition of the present invention can be applied to the surface of the skin for the treatment of various skin conditions or irritations, such as diaper rash, dry skin, ulcers, superficial cuts, scrapes, wounds, and first-degree burns. Areas of the skin that can be treated include the buttocks, especially in the case of diaper rash/incontinence dermatitis, as well as the arms, elbows, hands, abdomen, back, sacrum, coccyx, hips, knees, feet, ankles, heels, and the like. Once the composition reaches the surface of the skin, the propellant can evaporate, leaving a substantially uniform coating of the base zinc oxide composition on the skin. Further, the zinc oxide particles can be distributed in a substantially uniform manner throughout the coating. The amount of zinc oxide present in the composition on the skin after the composition is sprayed onto the skin in the form of a substantially uniform coating is from about 0.25 wt.% to about 35 wt.%, such as from about 0.5 wt.% to about 30 wt.%, such as from about 1 wt.% to about 25 wt.%, such as from about 5 wt.% to about 15 wt.%, based on the total weight of the resulting coating (e.g., the sprayable zinc oxide composition excluding volatile components such as propellants).

The present invention may be better understood by reference to the following examples.

Example 1

A sprayable zinc oxide composition to which a propellant is added is formed from a base zinc oxide composition comprising a preservative phase, an oil phase, and an aqueous phase. First, to prepare the preservative phase of the base zinc oxide composition, antifreeze is added to a beaker and stirred using a propeller. Then, the preservative is added to the beaker and mixing is initiated using a stirrer equipped with an anchor-type side-impact stirrer. Agitation is continued for at least 15 minutes until the solution is completely dissolved. The preservative phase is then allowed to stand.

Next, to prepare the oil phase of the base zinc oxide composition, add the emollient to a separate beaker and use a propeller to begin mixing while maintaining the temperature between 20°C and 23°C. Then add the Polyglyceryl-4 Isostearate/Cetyl Dimethicone Copolyol/Hexyl Laurate emulsifier, followed by the Cetyl PEG/PPG-10/1 Dimethicone emulsifier, Sorbitan Oleate emulsifier, Polysorbate 80 emulsifier, and Octyldodecanol/Octyldodecanol Xyloside/PEG-30 emulsifier. Continue mixing with agitation while maintaining the temperature between 20°C and 25°C. Next, add the silicone oil to the beaker while maintaining the temperature between 20°C and 23°C. Then, use a homogenizer to agitate, using chilled water to maintain the temperature between 20°C and 25°C, and then add the conditioning agent. Continue agitating for at least 15 minutes until the solution is completely dissolved, maintaining the temperature between 20°C and 28°C. The oil phase of the resulting basic zinc oxide composition has an HLB value of 6 to 7.

Next, prepare the aqueous phase of the base zinc oxide composition in a separate beaker. Add water to the beaker while maintaining the temperature between 20°C and 28°C. Begin mixing using a blender equipped with a stainless steel triple-propeller blade. Add the water-soluble conditioning agent to the beaker and continue mixing for at least 15 minutes until all solids have dissolved. Then, add the viscosity modifier, consisting of hydroxyethyl acrylate/sodium acryloyldimethyl taurate copolymer, squalane, and polysorbate 60, to the beaker and continue mixing for at least 15 minutes.

To prepare the base zinc oxide composition emulsion, maintain the temperature of the oil phase beaker at 20°C to 25°C. Then, slowly transfer the aqueous phase to the oil phase beaker while agitating with a homogenizer, with the transfer time being at least 20 minutes. Increase the homogenizer speed as needed while maintaining the temperature at 20°C to 25°C. The resulting water-in-oil emulsion is then covered and mixed for at least 30 minutes. The preservative phase is then added to the beaker while mixing continuously for at least 15 minutes while maintaining the temperature at 20°C to 25°C. After ensuring all powder has left the surface and increasing the mixing speed as needed, the zinc oxide granules are added while agitating with a homogenizer and mixed for at least 5 minutes, increasing the speed as needed while maintaining the temperature at 20°C to 25°C. Then, the viscosity modifier, aluminum starch octenylsuccinate, is added while agitating with a homogenizer and mixed for at least 5 minutes, increasing the speed as needed while maintaining the temperature at 20°C to 25°C. The fragrance is then added to the beaker while agitating with a homogenizer, and the emulsion is mixed for at least 15 minutes. The resulting base zinc oxide composition had an HLB value of 7.42.

After the base zinc oxide composition is formed, it is filled into an aerosol spray container, after which the valve of the container is sealed or crimped onto the top of the container. HFO-1234ze propellant is then pressure-filled into the container through the valve at a pressure of approximately 200 pounds. The resulting sprayable zinc oxide composition is a substantially uniform blend of the propellant and the base zinc oxide composition, comprising 22 wt.% propellant and 78 wt.% base zinc oxide composition. The sprayable composition has a specific gravity of approximately 1.045. The weight percentages of the components used in the sprayable zinc oxide composition are summarized in Table 1 below. Once sprayed onto a surface (e.g., skin) as a substantially uniform coating, the composition comprises 10.4 wt.% zinc oxide particles due to volatilization of the propellant.

Table 1 - Components of Sprayable Zinc Oxide Compositions

These and other modifications and changes of the present invention can be implemented by those of ordinary skill in the art without departing from the spirit and scope of the present invention. In addition, it should be understood that the aspects of the various embodiments can be interchanged in whole or in part. In addition, it will be understood by those of ordinary skill in the art that the foregoing description is only by way of example, and is not intended to be limited to the present invention further described in such appended claims.

Claims (22)

1. A sprayable zinc oxide composition comprising a fluoroolefin propellant and zinc oxide particles, wherein the composition comprises one or more nonionic lipophilic emulsifiers and one or more nonionic hydrophilic emulsifiers, wherein the weight ratio of the nonionic lipophilic emulsifier to the nonionic hydrophilic emulsifier is 5 to 30, wherein the composition is a water-in-oil emulsion and has a hydrophilic-lipophilic balance value of 3 to 8; wherein the composition comprises 2 wt.% to 30 wt.% zinc oxide particles based on the total weight of the composition; wherein the fluoroolefin propellant has a specific gravity of 1.03 to 1.3, a vapor pressure of less than 60 psi at 21°C, and a molecular weight greater than 100 g/mol; and wherein the composition optionally comprises one or more viscosity modifiers and the composition has a viscosity greater than 1000 centipoise. 2. The sprayable zinc oxide composition of claim 1, wherein the composition comprises 5 wt.% to 95 wt.% of a fluoroolefin propellant and 2 wt.% to 20 wt.% of zinc oxide particles based on the total weight of the composition. 3. The zinc oxide composition of claim 1 or 2, wherein the fluoroolefin propellant has a first specific gravity and the composition has a second specific gravity, wherein the ratio of the first specific gravity to the second specific gravity is 0.7 to 1.6. 4. The sprayable zinc oxide composition of claim 1, wherein the composition has a specific gravity of 0.8 to 1.3. 5. The sprayable zinc oxide composition of claim 1, wherein the fluoroolefin propellant is uniformly dispersed throughout the composition. 6. The sprayable zinc oxide composition of claim 1, wherein the propellant has the following general formula: Each R is independently fluorine, bromine, iodine, or hydrogen. R' is (CR ₂ ) _n Y, Y is CRF ₂ , and n is 0 or 1. 7. The sprayable zinc oxide composition of claim 1, wherein the fluoroolefin propellant comprises 1,1,1,3-tetrafluoropropylene. 8. The sprayable zinc oxide composition according to any one of claims 1 to 7, further comprising a carrier fluid. 9. The sprayable zinc oxide composition of claim 8, wherein the carrier fluid is a water-in-oil emulsion. 10. The sprayable zinc oxide composition according to any one of claims 1 to 7, wherein water is present in an amount of less than 50 wt.% based on the total weight of the composition. 11. The sprayable zinc oxide composition according to any one of claims 1 to 7, wherein the nonionic lipophilic emulsifier has a hydrophilic-lipophilic balance value greater than 2 and less than 8. 12. The sprayable zinc oxide composition according to any one of claims 1 to 7, further comprising one or more emollients, conditioning agents, antifreeze agents, preservatives, or combinations thereof. 13. The sprayable zinc oxide composition according to any one of claims 1 to 7, wherein the composition comprises uniformly distributed zinc oxide particles. 14. The sprayable zinc oxide composition according to any one of claims 1 to 7, wherein less than 3 wt.% of the zinc oxide particles in the composition settle when the composition is stored in a container at 21°C for 3 days. 15. A method for forming a sprayable zinc oxide composition, comprising: A basic zinc oxide composition is formed, wherein the basic zinc oxide composition comprises zinc oxide particles and a carrier fluid, wherein the carrier fluid is formed by combining an aqueous phase with an oil to form a water-in-oil emulsion and optionally adding one or more viscosity modifiers, wherein the oil phase comprises one or more nonionic lipophilic emulsifiers and one or more nonionic hydrophilic emulsifiers, wherein the weight ratio of the nonionic lipophilic emulsifier to the nonionic hydrophilic emulsifier is 5 to 30, wherein the composition is a water-in-oil emulsion and has a hydrophilic-lipophilic balance value of 3 to 8; wherein the composition comprises 2 wt.% to 30 wt.% zinc oxide particles based on the total weight of the composition; The basic zinc oxide composition is introduced into the spray container; and A hydrofluoroolefin propellant is injected into the container; wherein the hydrofluoroolefin propellant has a specific gravity of 1.03 to 1.3, a vapor pressure of less than 60 psi at 21°C, and a molecular weight of greater than 100 g per mole; and wherein the composition optionally contains one or more viscosity modifiers and the composition has a viscosity of greater than 1000 centipoise. 16. The method of claim 15, wherein at least one viscosity modifier is added to the aqueous phase. 17. The method of claim 15, wherein the propellant is uniformly dispersed throughout the composition. 18. The method of claim 15, wherein the zinc oxide particles are uniformly dispersed throughout the composition. 19. The method of claim 15, further comprising adding one or more preservatives, emollients, skin conditioners, antifreeze agents, or combinations thereof to the composition. 20. The method of claim 15, wherein the hydrofluoroolefin propellant has a first specific gravity and the sprayable zinc oxide composition has a second specific gravity, wherein the ratio of the first specific gravity to the second specific gravity is 0.7 to 1.6. 21. The method of claim 15, wherein the sprayable zinc oxide composition is formed at a temperature of 15°C to 40°C. 22. The method of claim 15, wherein the nonionic lipophilic emulsifier has a hydrophilic-lipophilic balance value greater than 2 and less than 8.