Encapsulated aluminum compositions

Abstract: Encapsulated aluminum salts are produced by combining and heating an aqueous aluminum salt selected from aluminum halohydrate, aluminum nitrohydrate and mixtures thereof, or aluminum-zirconium halohydrates and mixtures thereof; a hydrophobic liquid; and a carboxylate. The mixture is heated until substantially all of the free water has been removed. The encapsulated aluminum salts precipitate out after the removal of the water. The encapsulated aluminum salts are useful in deodorant and antiperspirant compositions.

Description: This invention pertains to encapsulated aluminum halohydrate, aluminum-zirconium halohydrate or aluminum nitrohydrate compounds encapsulated in a shell comprising a carboxylate, such as stearic acid. The aluminum salts are released from the encapsulant in the presence of moisture and are useful in deodorant and antiperspirant compositions. In antiperspirant or deodorant compositions, it is known to encapsulate or coat a deodorant active or a fragrance added to the deodorant or antiperspirant composition, however, it is virtually unknown to encapsulate antiperspirant actives with a carboxylate according to this invention. EP Patent No. 0303461 to Wright teaches antiperspirant and deodorant compositions containing moisture sensitive capsules which in the presence of moisture release sensory agents such as perfumes, skin coolants, emollients, or other benefit agents such as deodorant actives, antiperspirant actives, and anticholinergic actives. The special polymer from which the capsules are formed is preferably a polysaccharide. The method for preparing the capsules comprises preparing an emulsion of water, the special polymer and the sensory or benefit agent and spray drying the emulsion. The only benefit obtained through the encapsulation of the antiperspirant active is believed to be the ability to produce stable alcoholic compositions and release of the agent in the presence of moisture. U.S. Patent No. 4,524,062 to Laba et al. teaches an antiperspirant/deodorant stick composition which comprises a powdered antiperspirant active, a coating material for the antiperspirant active, a deodorant and a cologne stick base. The coating material is typically a glycol stearate and the coated antiperspirant active is achieved by blending the antiperspirant active and the glycol stearate at a temperature at which the glycol stearate is a liquid. U.S. 4,524,062 does not teach a process for obtaining the antiperspirant active in an encapsulated form and there is no evidence to show that the antiperspirant active is even coated and not merely suspended in the glycol stearate. It is an object of this invention to show encapsulated aluminum halohydrate, aluminum nitrohydrate compositions and mixtures thereof, or aluminum-zirconium halohydrate compositions and mixtures thereof; a method for producing the encapsulated aluminum compositions, preferably having a controlled particle size and shape; and deodorant and antiperspirant compositions comprising the encapsulated aluminum salts. The encapsulated aluminum salts of this invention are comprised of aluminum halohydrate, aluminum nitrohydrate or mixtures thereof (herein referred to only as aluminum hydrate) or aluminum-zirconium hydrates contained in a shell comprised of a carboxylic acid or carboxylic acid derivative (herein referred to as carboxylate). Upon contact with moisture, the shell opens up and releases the aluminum salt. Some or all of the aluminum salt may be dissolved in the moisture depending on the concentration of the salt and the amount of moisture. The encapsulated aluminum salts of this invention are produced by combining together an aqueous aluminum hydrate or aluminum-zirconium halohydrate salt, a non-water miscible hydrophobic liquid (herein referred to as hydrophobic liquid), and a carboxylate and heating the mixture, with agitation, to a temperature sufficient to remove substantially all free water. Some of the hydrophobic liquid may be removed during the heating because of an azeotrope that may form between the hydrophobic liquid and the water. It is important that the rate of water distillation be faster than the rate of the hydrophobic solvent distillation. It is preferred that any azeotrope formed contain more than 50% by weight of water. After the removal of the water, the encapsulated aluminum salts precipitate out of the reaction medium. Typically, an increase in the temperature will occur when the distillation of the aqueous phase is complete. Upon completion of the distillation, there should be enough fluid remaining to keep the encapsulated aluminum salts free flowing. The encapsulated aluminum salts can then recovered from the reaction medium through separation means such as filtration. The aqueous aluminum hydrates useful in the instant invention are those currently known in the art. The aluminum hydrates may be exemplified by aluminum nitrohydrate and aluminum halohydrates such as aluminum chlorohydrate, aluminum bromohydrate, and aluminum iodohydrate; and mixtures thereof. The aluminum hydrates useful in the instant invention may be further described as a standard (non-activated) or an activated salt. An activated salt, through compositional differences, is more efficacious when used in antiperspirant compositions. The aluminum hydrates useful in the instant invention may be further described by the formula Al a (OH) b X c where 1/3 ≦ a/c ≦ 2.2/1; c has the value of 0 to 5.9, 3a=b+c ; and X is selected from Cl, Br, I and NO₃. The aluminum hydrate is supplied as an aqueous solution containing greater than 0% by weight of the aluminum hydrate. The maximum amount of aluminum hydrate in the aqueous solution is dependent upon its solubility in water. Typically the aluminum hydrate is used as an aqueous solution comprising 10% to 50% by weight of the aluminum hydrate. Aqueous solutions containing less than 10% by weight of the aluminum hydrate may be used to produce an encapsulated aluminum salt, however, they are not economically advantageous. Aqueous solutions containing greater than 50% by weight of the aluminum hydrate are not well known in the art however, they are useful when obtainable. The aqueous aluminum hydrates useful in the instant invention are commercially available or may be produced using methods known in the art. The aqueous aluminum-zirconium halohydrates useful in the instant invention are those currently known in the art. The aluminum-zirconium halohydrates may be exemplified by aluminum-zirconium chlorohydrate, aluminum-zirconium bromohydrate, and aluminum-zirconium iodohydrate and mixtures thereof. The aluminum-zirconium halohydrates are typically buffered with an amino acid such as glycine. The aluminum-zirconium halohydrates useful in the instant invention may be further described as a standard (non-activated) or an activated salt. An activated salt, through compositional differences, is more efficacious when used in antiperspirant compositions. The aluminum-zirconium halohydrates useful in the instant invention may be further described by the formula Al a Zr b (OH) c X d where a/b has the value of 0 to 20, b has a value of greater than 0, 3a+4b=c+d ; and X is selected from Cl, Br, I and NO₃. The aluminum-zirconium halohydrate may be supplied as an aqueous solution containing greater than 0% by weight of the aluminum-zirconium halohydrate. The maximum amount of aluminum-zirconium halohydrate in the aqueous solution is dependent upon its solubility in water. Typically, the aluminum-zirconium halohydrate is used as an aqueous solution comprising 10% to 40% by weight of the aluminum-zirconium halohydrate. Aqueous solutions containing less than 10% by weight of the aluminum-zirconium halohydrate may be used to produce an encapsulated aluminum-zirconium salt, however, they are not economically advantageous. Aqueous solutions containing greater than 40% by weight of the aluminum-zirconium halohydrate are not well known in the art however, they are useful when obtainable. Non-water miscible hydrophobic liquids useful in the instant invention may be selected from low viscosity silicone fluids, paraffin oils such as mineral oil and mixtures thereof. The low viscosity silicones and further, low viscosity cyclic silicones are the preferred hydrophobic liquid. Low viscosity silicones useful in the instant invention are selected from cyclic and linear silicones and mixtures thereof which have a viscosity of less than 1,000 mm²/s (centistoke). The cyclic low viscosity silicones may be exemplified by compounds having the formula wherein each R is independently selected from an alkyl group containing 1 to 30 carbon atoms and an aryl group containing 6 to 10 carbon atoms and x has the value of 3 to 10. The preferred cyclic low viscosity silicone is when R is predominantly methyl and x is 4 to 5. The cyclic low viscosity silicones may be further exemplified by, but not limited to hexamethylcyclotrisiloxane, octamethylcyclotetrasiloxane, decamethylcyclopentasiloxane, dodecamethylcyclohexasiloxane and mixtures thereof. The linear low viscosity silicones may be exemplified by compounds having the formula wherein each R is independently selected from an alkyl group containing 1 to 30 carbon atoms and an aryl group containing 6 to 10 carbon atoms, R'' is selected from R and a hydroxyl (-OH) group; and y has the value such that the viscosity of the silicone is less than 1,000 mm²/s (centistoke). The preferred linear low viscosity silicone is when R is predominantly methyl. The linear low viscosity silicones may be further exemplified by, but not limited to, trimethylendblocked dimethylpolysiloxane fluids, 5, 10, 25 and 50 mm²/s (cs) dimethylpolysiloxane fluids, octamethyltrisiloxane, decamethyltetrasiloxane, hydroxyl endblocked polydimethylsiloxanes and mixtures thereof. The carboxylic acids and carboxylic acid derivatives (carboxylates) useful in the instant invention are selected from the group consisting of carboxylic acids, alkali metal carboxylates, glyceryl carboxylates, carboxylic acid anhydrides, carboxylic acid chlorides and mixtures thereof. The carboxylates useful in the instant invention may be further exemplified by the formulas: wherein R¹ is selected from the group consisting of a saturated or unsaturated, branched or linear alkyl group consisting of at least 2 carbon atoms and a substituted or unsubstituted phenyl group containing at least 6 carbon atoms; and Z is selected from the groups consisting of the hydrogen atom, alkali metals and glyceryl. R¹ may be further exemplified by, but not limited to ethyl, propyl, octyl, decyl, undecyl, pentadecyl, hexadecyl, octadecyl, doeicosyl, phenyl, phenyl ethylene, and others. Z may be further exemplified by, but not limited to, the hydrogen atom, sodium, potassium, -CH₂CH(OH)CH₂OH, and -CH(OH)CH₂OH. For the carboxylate to be useful in the instant invention, it is necessary for the carboxylate to be soluble in the hydrophobic liquid and/or to have a melting point less than the water distillation temperature and further, the carboxylate must not be completely distillable at the water distillation temperature. When using a carboxylate where Z is an alkali metal it may be necessary to add a co-solvent, such as water, to completely dissolve the alkali metal carboxylate. The carboxylates useful in the instant invention may be further exemplified by, but not limited to, butyric acid, caprylic acid, lauric acid, palmitic acid, stearic acid, behenic acid, oleic acid, linoleic acid, linolenic acid, phenylacetic acid, sodium stearate, sodium palmitate, potassium stearate, glyceryl monostearate, stearic anhydride, palmitic anhydride, lauric anhydride, stearoyl chloride, myristoyl chloride, octanoyl chloride and mixtures thereof. The preferred carboxylate is stearic acid due to it being a cosmetically acceptable ingredient and it has the acceptable properties to make it useful. The encapsulated aluminum salts are formed by combining at least 7 millimoles carboxylate for every 100 parts of aluminum hydrate solids, and at least 1 part of hydrophobic liquid for every part of water. It is preferred to use between 28 to 200 millimoles of carboxylate per every 100 parts of aluminum hydrate solids and at least 1.25 parts hydrophobic liquid per every part of water. The encapsulated aluminum-zirconium salts are formed by combining at least 14 millimoles of carboxylate for every 100 parts of aluminum-zirconium halohydrate solids, and at least 1 part of hydrophobic liquid for every part of water. It is preferred to use between 35 to 200 millimoles of carboxylate per every 100 parts of aluminum-zirconium halohydrate solids and at least 1.25 parts hydrophobic liquid per every part of water. It may be possible to use less than 1 part of hydrophobic liquid for every part of water if the amount of hydrophobic liquid lost in the distillation azeotrope is replaced during the encapsulation. The aqueous aluminum hydrate or aluminum-zirconium halohydrate, carboxylate and hydrophobic liquid are combined and heated, with agitation, to a temperature sufficient to remove substantially all free water from the solution (water distillation temperature). Typically, temperatures greater than 100°C. at atmospheric pressure are useful for removing the free water. The preferred temperature for the removal of the water is 100° to 130°C. When the water has been removed the temperature will rise above the water distillation temperature. It is preferred that the temperature does not exceed 150°C. for an extended period of time. Temperatures which exceed 150°C. for an extended period of time may be detrimental to the encapsulant and lead to fragmentation or cracking of the shell and possibly the conversion of the aluminum halohydrate into an aluminum oxide or the aluminum-zirconium halohydrate into an aluminum-zirconium oxide. Pressures greater or less than atmospheric pressure can be employed in the method of the instant invention thereby allowing the mixture to be heated to higher or lower temperatures for the removal of the water. It is essential that the water be removed during the heating step. Merely heating to temperatures greater than 100°C while refluxing, or containing the water otherwise, will not result in an encapsulated aluminum salt. Typically, the completion of the water removal will be indicated by an increase in the temperature above the water distillation temperature. After the removal of the free water from the mixture, the encapsulated aluminum salts precipitate out of the reaction medium. The encapsulated aluminum salts are typically recovered from the reaction medium by filtration means such as gravimetric, pressure or vacuum filters or by other separation means such as decanting or centrifuging. Filtration means will vary depending on the batch size. It is preferred to recover the encapsulated aluminum salts from the reaction medium at a temperature at or above the temperature at which the carboxylate is a liquid. It is further preferred to recover the encapsulated aluminum salts from the reaction medium using filtration means. After the encapsulated aluminum salts have been recovered by filtration means from the reaction medium, they may be optionally washed using a hydrophobic solvent to remove any excess carboxylate that might be adhered to the shells. If the carboxylate is not a liquid at room temperature, it may be necessary to heat the hydrophobic liquid to a temperature at which the carboxylate is a liquid during the wash. It is theorized that the shell material of the encapsulated aluminum salt is comprised of mostly carboxylate, however, it may contain some hydrophobic liquid which may have been entrapped within the coating. Further, it is theorized that the shell comprises less than 5% and more likely less than 1% of the total encapsulated aluminum salt mass. It is further theorized that the coating thickness is dependent upon the concentration of the carboxylate used. Typically the shells are spherical in nature however, they may also be elliptical, elongated or shaped otherwise. The standard aluminum salts do not appear to undergo a compositional change during the encapsulation process based on High Performance Liquid Chromatography (HPLC). The aluminum salts do not appear to be released from within the shell in any solvent or liquid except water or solvents containing water. In the presence of water, the shells open up releasing the aluminum hydrate salt and some or all of the aluminum hydrate salt may be dissolved in the water. Certain solvents such as paraffin oil, toluene, ethanol, hexanes, propylene glycol, isopropyl myristate, and silicone glycol copolymers, did not appear to affect the shell or release the salt. Another aspect of this invention is the ability to produce encapsulated aluminum salts having a controlled particle size and shape. This aspect is accomplished by control of the concentration of the carboxylate and control of the agitation rate. The encapsulated aluminum hydrate salts of this invention are produced using 7 or more millimoles of carboxylate per every 100 parts aluminum hydrate solids. The encapsulated aluminum-zirconium salts of this invention are produced using 15 or more millimoles of carboxylate per every 100 parts aluminum-zirconium halohydrate solids. As the amount of carboxylate used increases, the beads formed become more spherical in shape and uniform in size. Thus, the use of higher amounts of carboxylate may result in uniform, spherical beads. Particle size distribution is controlled by the agitation rate (the rate of agitation during the water distillation). Encapsulated aluminum salts which resemble impalpable powder (5 to 75 µm) (5 to 75 microns) can be produced at higher agitation rates. Because of equipment differences, mixing characteristics and other factors, it is not possible to specify an exact agitation rate that will produce an exact particle size however, one skilled in the art would be able to determine this for a specific apparatus. The encapsulated aluminum salts of the instant invention are useful in deodorant and antiperspirant compositions such as aerosols, roll-ons and sticks. It is preferable for the deodorant and antiperspirant compositions to be anhydrous, however, it is not necessary. The aerosol compositions are typically comprised of 1 to 25% by weight aluminum hydrate salts or 1 to 20% by weight aluminum-zirconium halohydrate salts, preferably 8 to 12 wt% of an encapsulated aluminum salt; 50 to 90% by weight of a propellant, such as butane, isobutane, propane, nitrogen, carbon dioxide; and 5 to 15% by weight of an anhydrous carrier such as ethanol and cyclomethicone. Optional ingredients, such as cyclomethicone, dimethicone, isopropyl myristate, isopropyl palmitate, fragrance, deodorants, valve lubricants, talc, silica, suspending aids, polar activators, and others may be added into the aerosol compositions to improve the aesthetics or to change the characteristics of the propulsion. The aerosol compositions are produced using methods known in the art. The roll-on compositions are typically comprised of 1 to 20 or 25% by weight, depending on the particular salt used, per above, preferably 10 to 25 wt% of an encapsulated aluminum salt; 60 to 95%, optionally 60 to 90% by weight of a carrier liquid, such as water, cyclomethicone, organic esters and derivatives of organic esters, dioctyl adipate and others; and optionally 0.1 to 5% by weight of a suspending aid or 0.1 to 10 % by weight of an emulsifier, such as glyceryl monostearate, steareth-2, alkoxylates and others. If a suspending aid is used 0.1 to 2% of a polar activator must also be added. Other optional ingredients, such as fragrance, deodorants, talc, silica, dimethicone, polyethylene, silica, aluminum sulfate, starch, octenyl succinate and others, may be added into the roll-on compositions to improve the aesthetics or increase the viscosity of the composition. The roll-on compositions are produced using methods known in the art. The stick compositions are typically comprised of 1 to 20 or 25% by weight, depending on the particular salt used, per above, preferably 15 to 25 wt% of an encapsulated aluminum salt; 20 to 65% by weight of a carrier fluid such as cyclomethicone, ethanol, and propylene glycol; and 5 to 30% by weight of a waxy gellant such as cetyl alcohol, stearyl alcohol, and hydrogenated caster oil. Optional ingredients, such as organic esters, organic ethers, emulsifiers, talc, dimethicone, silica, fragrance, deodorants, polyethylene and others, may be added to the stick compositions to improve the aesthetics or application of the encapsulated aluminum salt. The stick compositions are produced using methods known in the art. Deodorant and antiperspirant compositions such as pump sprays, creams, lotions and others may also formulated with the encapsulated aluminum salts. The term "parts" employed herein refers to parts by weight. Particle Size Analysis: The particle size of the encapsulated aluminum salts was determined by using a Malvern 3600 EZ particle sizer. For analysis, the encapsulated aluminum salts were suspended in a solvent selected from either toluene or cyclomethicone and the stir speed was set at 4. Physical Characteristics: The physical characteristics of the encapsulated aluminum salts (shape, cracks, jagged edges, etc.) was determined by observing the encapsulated aluminum salts under a 40x microscope. Some of the encapsulated and unencapsulated aluminum salts were analyzed by HPLC according to the method taught in European Patent Application 0 256 831. Sample preparation for the encapsulated aluminum salts comprises weighing 1.0 gram of the encapsulated aluminum salt into a vial and adding 0.01 N HCl to the vial until the total sample weight is 10 grams. The sample is shaken. 2 to 3 ml of the liquid are drawn off and filtered through a 0.45 µm (0.45 micron) syringe filter. The injected sample size is 2.0 microliters. In the instant application, Peak 4 corresponds with Band III, Peak 3 corresponds with Band II and Peak 2 corresponds with Band I defined in European Patent Application 0 256 831. Elemental analysis was also done on some to the materials produced by the examples herein to determine the encapsulant. Example 1 50 grams of a mixture comprised of octamethylcyclotetrasiloxane and decamethylcyclopentasiloxane and 5 grams of stearic acid were combined in a beaker and heated to 100°C. 25 grams of a 50% aqueous solution of Aluminum Chlorohydrate in deionized water was slowly added to the stearic acid solution while increasing agitation. The temperature of the reaction mixture was maintained around 125° to 130°C. during the evaporation of the water (approximately 5 minutes). The reactant mixture was then vacuum filtered (while hot), using a Buchner funnel, to recover the encapsulated aluminum salt. The resulting encapsulated aluminum salt was comprised of particles that were spherical and uniform. The average particle size was determined to be 10 to 40 µm (10 to 40 microns). There were no jagged edges on the encapsulated aluminum salts. The same experiment was repeated. The temperature of the reaction mixture was maintained around 125° to 130°C. during the evaporation of the water (approximately 30 minutes). The reactant mixture was then vacuum filtered (while hot), using a Buchner funnel, to recover the encapsulated aluminum salt. The resulting encapsulated aluminum salt was comprised of particles that were spherical. Some of the encapsulated aluminum salt particles had shells which were cracked. Example 2 200 grams of a mixture comprised of octamethylcyclotetrasiloxane and decamethylcyclopentasiloxane and 5 grams of stearic acid were combined in a beaker and heated to 100°C. 100 grams of aqueous Aluminum Chlorohydrate (50% solids) was slowly added to the stearic acid solution while increasing agitation. The temperature of the reactant mixture was maintained around 110°C. during the evaporation of the water (approximately 20 minutes). When the water removal was complete, the temperature increased to 145°C. before heating was discontinued. The reactant mixture was then vacuum filtered (while hot), using a Buchner funnel, to recover the encapsulated aluminum salt. Some of the particles were spherical and some were elliptical. There were no jagged edges on the particles or broken pieces, however, some of the shells were cracked. Example 3 100 grams of a mixture comprised of octamethylcyclotetracyclicsiloxane and decamethylcyclopentasiloxane and 2 grams of stearic acid were combined in a beaker and heated to 100°C. 50 grams of aqueous Aluminum Chlorohydrate (50% solids) was slowly added to the stearic acid solution while increasing agitation. The reactant mixture was maintained at a full boil (approx. 107°C) for approximately 25 minutes during the evaporation of the water. After the water had been removed, the temperature rose to 130°C. before heating was stopped. The reactant mixture was then vacuum filtered (while hot), using a Buchner funnel, to recover the encapsulated aluminum salt. The particles were very fine, uniform and all spherical. There were no jagged edges on the particles or broken pieces and none of the shells were cracked. Example 4 2000 grams of a mixture comprised of octamethylcyclotetracyclicsiloxane and decamethylcyclopentasiloxane and 40 grams of stearic acid were combined in a beaker and heated to 100°C. 1000 grams of aqueous Aluminum Chlorohydrate (50% solids) was slowly added to the stearic acid solution while increasing agitation. The temperature of the reactant mixture was maintained around 80°C during the addition. The reactant mixture was heated for approximately 1.8 hours at a temperature of approximately 100°C (full boil), while evaporating off the water. When the water removal was complete, the temperature increased to 126°C. before heating was stopped. The reactant mixture was then vacuum filtered (while hot), using a Buchner funnel, to recover the encapsulated aluminum salt (509 grams). The particles were fine spherical beads. The encapsulated aluminum chlorohydrate salt was tested for %Cl, %Al, %C, %H and %Si using elemental analysis techniques. The results were: 16.2% Cl, 23.3% Al, 0.43% C, 4.07% H, and <2% Si. From the carbon content, it is estimated that approximately 0.6% of the encapsulated aluminum chlorohydrate composition is stearic acid. Example 5 100 grams of a mixture comprised of octamethylcyclotetracyclicsiloxane and decamethylcyclopentasiloxane and 4 grams of behenic acid were combined in a beaker and heated to 100°C. 50 grams of aqueous Aluminum Chlorohydrate (50% solids) was slowly added to the stearic acid solution while increasing agitation. The temperature of the reactant mixture was maintained around 100°C during the evaporation of the water. After the removal of the water was complete the temperature rose to 130°C. before heating was stopped. The mixture was then vacuum filtered (while hot), using a Buchner funnel, to recover the encapsulated aluminum salt. The particles were slightly yellow in color and mostly angular particles. There were very few spheres. The encapsulated aluminum chlorohydrate salt was tested for %Cl, %Al, %C, %H and %Si using elemental analysis techniques. The results were: 15.6% Cl, 22% Al, 0.60% C, 3.87% H, and <2% Si. Example 6 150 grams of a mixture comprised of octamethylcyclotetracyclicsiloxane and decamethylcyclopentasiloxane and 9.0 grams of glyceryl monostearate were combined in a 500 ml round bottom flask equipped with a paddle-blade agitator, a water cooled condenser and a 250 ml round bottom receiver. The mixture was heated to 72°C. 150 grams of aqueous Aluminum Chlorohydrate (50% solids) was added to the glyceryl monostearate solution, with agitation. The mixture was heated for approximately 2.5 hours, while distilling off the water, maintaining a temperature around 105°C. The reaction was stopped when the pot temperature reached approximately 138°C. and no more water was observed to be distilling off. The mixture was then vacuum filtered (while hot, ∼ 83°C.), using a Buchner funnel, to recover the encapsulated aluminum salt. Example 7 150 grams of a mixture comprised of octamethylcyclotetracyclicsiloxane and decamethylcyclopentasiloxane and 9.0 grams of sodium stearate were combined in a 500 ml round bottom flask equipped with a paddle-blade agitator, a water cooled condenser and a 250 ml round bottom receiver. The mixture was heated to 90°C. 100 grams of distilled water was then added to dissolve the sodium stearate. 150 grams of aqueous Aluminum Chlorohydrate (50% solids) was added to the sodium stearate solution, with agitation. The mixture was heated for approximately 4 hours, while distilling off the water, maintaining a temperature around 105°C. The reaction was stopped when the temperature had reached 180°C. and no more water was observed to be distilling off. The mixture was then vacuum filtered (while hot, ∼ 85°C.), using a Buchner funnel, to recover the encapsulated aluminum salt. Example 8 150 grams of a polydimethylsiloxane fluid having a viscosity of 10 mm²/s (centistokes) and 9.0 grams of stearic acid were combined in a 500 ml round bottom flask equipped with a paddle-blade agitator, a water cooled condenser and a 250 ml round bottom receiver. The mixture was heated to 70°C. 150 grams of aqueous Aluminum Chlorohydrate (50% solids) was added to the stearic acid solution, with agitation. The mixture was heated for approximately 4 hours, while distilling off the water, maintaining a temperature around 110°C. During the distillation, slight foaming was noticed which was controlled by adjusting the agitation speed. The reaction was stopped when the temperature had reached 130°C. and no more water was observed to be distilling off. The mixture was then vacuum filtered (while hot, ∼ 80°C.), using a Buchner funnel, to recover the encapsulated aluminum salt. Example 9 150 grams of paraffin oil and 9.0 grams of stearic acid were combined in a 500 ml round bottom flask equipped with a paddle-blade agitator, a water cooled condenser and a 250 ml round bottom receiver. The mixture was heated to 70°C. 150 grams of aqueous Aluminum Chlorohydrate (50% solids) was added to the stearic acid solution, with agitation. The mixture was heated for approximately 2 hours, while distilling off the water, maintaining a temperature around 120°C. The reaction was stopped when the temperature had reached 142°C. and no more water was observed to be distilling off. The mixture was then vacuum filtered (while hot, ∼ 75°C.), using a Buchner funnel, to recover the encapsulated aluminum salt. Example 10 200.1 grams of a mixture comprised of octamethylcyclotetracyclicsiloxane and decamethylcyclopentasiloxane (cyclomethicone) and 4.0 grams of stearic anhydride were combined in a 500 ml round bottom flask equipped with a paddle-blade agitator, a water cooled condenser and a 250 ml round bottom receiver. The mixture was heated to 90°C. 100 grams of aqueous Aluminum Chlorohydrate (50% solids) was added to the stearic anhydride solution, with agitation. The mixture was heated for approximately 2 hours, while distilling off the water, maintaining a temperature around 102°C. The reaction was stopped when the pot temperature reached approximately 131°C. The mixture was then vacuum filtered (while hot, ∼ 85°C.), using a Buchner funnel, to recover the encapsulated aluminum salt. Example 11 200 grams of a mixture comprised of octamethylcyclotetracyclicsiloxane and decamethylcyclopentasiloxane (cyclomethicone) and 6.3 grams of stearoyl chloride were combined in a 500 ml round bottom flask equipped with a paddle-blade agitator, a water cooled condenser and a 250 ml round bottom receiver. The mixture was heated to 72°C. 100 grams of aqueous Aluminum Chlorohydrate (approximately 50% solids) was added to the stearoyl chloride solution, with agitation. The mixture was heated for approximately 2.5 hours, while distilling off the water, maintaining a temperature around 110°C. The reaction was stopped when the pot temperature reached approximately 128°C. The mixture was then vacuum filtered (while hot, ∼ 85°C.), using a Buchner funnel, to recover 53 grams of encapsulated aluminum salt. Example 12 Three experiments were conducted to determine the effect of agitation rate on particle size. In the experiments, 134.5 grams of a mixture comprised of octamethylcyclotetracyclicsiloxane and decamethylcyclopentasiloxane and 20 grams of stearic acid were combined in a 500 ml round bottom flask equipped with a paddle-blade agitator, a water cooled condenser and a 250 ml round bottom receiver and heated to 75°C. 192 grams of aqueous Aluminum Chlorohydrate (50% solids), was added to the stearic acid solution, with agitation. The mixture was heated while distilling off the water. The agitation during the distillation was maintained at various levels given in Table 1. The reaction was stopped when there was no more water observed to be distilling off. The mixture was then vacuum filtered using a Buchner funnel, to recover the encapsulated aluminum salt. The particle size of the resulting encapsulated aluminum salts was measured using a Malvern 3600 EZ particle sizer. Results are given in Table 1. Agitation Speed Particle Size (microns) Distribution µm Average µm 400 173 to 564 324 650 34 to 270 145 800 8 to 312 141 Example 13 A suspension stick composition was produced by heating 55 parts of cyclomethicone and 20 parts of stearyl alcohol to 65°C. with stirring. 2 parts of PPG-14 Butyl Ether was then added with continued stirring followed by 1 part of hydrogenated caster oil, 2 parts of talc and 20 parts of an encapsulated aluminum salt produced as in Example 1. The mixture was cooled to 53°C. and cast into a stick. Example 14 An aerosol composition was produced by mixing 12 parts of an encapsulated aluminum salt as produced in Example 1 with 10.5 parts of cyclomethicone and 2 parts of dimethicone. This mixture was loaded into an aerosol container and charged with 75.5 parts of propellant. Example 15 300 grams of a mixture comprised of octamethylcyclotetrasiloxane and decamethylcyclopentasiloxane and 9.9 grams of stearic acid were combined in a 1 liter beaker and heated to 80°C. 300 grams of aqueous Aluminum-Zirconium Tetrachlorohydrex-Gly (35% solids) was added to the stearic acid solution, with agitation. The mixture was heated for approximately 1 hour, while evaporating off the water, maintaining a temperature around 100°C. The reaction was stopped when the pot temperature reached approximately 110°C and no more water was observed to be evaporating off. The mixture was then vacuum filtered (while hot, ∼ 112°C.), using a Buchner funnel, to recover the encapsulated aluminum-zirconium salt. The encapsulated aluminum-zirconium salt appeared to be spherical and were white in color. Example 16 300 grams of a mixture comprised of octamethylcyclotetrasiloxane and decamethylcyclopentasiloxane and 11.88 grams of stearic acid were combined in a 1L round bottom flask equipped with a paddle-blade agitator, a water cooled condenser and a 1L round bottom receiver and heated to 67°C. 300 grams of aqueous Aluminum-Zirconium Tetrachlorhydrex-Gly (35% solids), heated to 70°C., was added to the stearic acid solution, with agitation. The mixture was heated for approximately 2.25 hours, while distilling off the water, maintaining a temperature around 110°C. The reaction was stopped when the pot temperature reached approximately 122°C. and no more water was observed to be distilling off. The mixture was then vacuum filtered (while hot, ∼ 122°C), using a Buchner funnel, to recover 108.6 grams of the encapsulated aluminum-zirconium salt. The beads were re-dispersed in 100 grams of a mixture comprised of octamethylcyclotetrasiloxane and decamethylcyclopentasiloxane and heated to 70°C. and filtered again. 104.1 grams of encapsulated aluminum-zirconium salt was recovered after the second filtration. The encapsulated aluminum-zirconium salts were mostly spheres of varying sizes. Example 17 300 grams of a mixture comprised of octamethylcyclotetrasiloxane and decamethylcyclopentasiloxane and 13.86 grams of stearic acid were combined in a 1 L beaker and heated to 70°C. 300 grams of aqueous Aluminum-Zirconium Tetrachlorhydrex-Gly (35% solids) was added to the stearic acid solution, with agitation. The mixture was heated for approximately 2 hours, while evaporating off the water, maintaining a temperature around 100°C. The reaction was stopped when the pot temperature reached approximately 112°C and no more water was observed to be evaporating off. The mixture was then vacuum filtered (while hot, ∼ 112°C.), using a Buchner funnel to recover the encapsulated aluminum-zirconium salts. Example 18 150 grams of a mixture comprised of octamethylcyclotetrasiloxane and decamethylcyclopentasiloxane and 6.3 grams of caprylic acid were combined in a 500 ml round bottom flask equipped with a paddle-blade agitator, a water cooled condenser an a 250 ml round bottom receiver. 150 grams of aqueous Aluminum-Zirconium Tetrachlorhydrex-Gly (35% solids) was added to the caprylic acid solution, with agitation. The mixture was heated for approximately 4 hours, while distilling off the water, maintaining a temperature around 110°C. The reaction was stopped when the pot temperature reached approximately 130°C. and no more water was observed to be distilling off. The mixture was cooled and vacuum filtered using a Buchner funnel, to recover the encapsulated aluminum-zirconium salt. Example 19 150 grams of a mixture comprised of octamethylcyclotetrasiloxane and decamethylcyclopentasiloxane and 6.3 grams of iso-stearic acid were combined in a 500 ml round bottom flask equipped with a paddle-blade agitator, a water cooled condenser an a 250 ml round bottom receiver. 150 grams of aqueous Aluminum-Zirconium Tetrachlorhydrex-Gly (35% solids) was added to the iso-stearic acid solution, with agitation. The mixture was heated for approximately 4 hours, while distilling off the water, maintaining a temperature around 107°C. The reaction was stopped when the pot temperature reached approximately 127°C. and no more water was observed to be distilling off. The mixture was vacuum filtered ( ∼ 80°C.) using a Buchner funnel, to recover the encapsulated aluminum-zirconium salt. The encapsulated aluminum-zirconium salts were uniform in size and mostly spherical. Example 20 150 grams of a mixture comprised of octamethylcyclotetrasiloxane and decamethylcyclopentasiloxane and 6.3 grams of behenic acid were combined in a 500 ml round bottom flask equipped with a paddle-blade agitator, a water cooled condenser an a 250 ml round bottom receiver and heated to approximately 75°C. 150 grams of aqueous Aluminum-Zirconium Tetrachlorhydrex-Gly (35% solids) was added to the behenic acid solution, with agitation. The mixture was heated for approximately 4.5 hours, while distilling off the water, maintaining a temperature around 102°C. The reaction was stopped when the pot temperature reached approximately 135°C. and no more water was observed to be distilling off. The mixture was vacuum filtered ( ∼ 135°C) using a Buchner funnel, to recover the encapsulated aluminum-zirconium salt. The particles were mostly spherical and yellow. Example 21 150 grams of a mixture comprised of octamethylcyclotetrasiloxane and decamethylcyclopentasiloxane and 6.3 grams of glyceryl monostearate were combined in a 500 ml round bottom flask equipped with a paddle-blade agitator, a water cooled condenser and a 250 ml round bottom receiver and heated to approximately 70°C. 150 grams of aqueous Aluminum-Zirconium Tetrachlorhydrex-Gly (35% solids) was added to the glyceryl monostearate solution, with agitation. The mixture was heated for approximately 3.5 hours, while distilling off the water, maintaining a temperature around 100°C. The reaction was stopped when the pot temperature reached approximately 130°C. and no more water was observed to be distilling off. The mixture was vacuum filtered ( ∼ 85°C) using a Buchner funnel, to recover the encapsulated aluminum-zirconium salt. The particles were mostly spherical. Example 22 150 grams of a mixture comprised of octamethylcyclotetrasiloxane and decamethylcyclopentasiloxane and 6.3 grams of sodium stearate were combined in a 500 ml round bottom flask equipped with a paddle-blade agitator, a water cooled condenser an a 250 ml round bottom receiver and heated to approximately 90°C. 100 grams of deionized water was added to dissolve the sodium stearate. 150 grams of aqueous Aluminum-Zirconium Tetrachlorhydrex-Gly (35% solids) was added to the sodium stearate solution, with agitation. The mixture was heated for approximately 3.5 hours, while distilling off the water, maintaining a temperature around 105°C. The reaction was stopped when the pot temperature reached approximately 135°C. and no more water was observed to be distilling off. The mixture was vacuum filtered ( ∼ 99°C) using a Buchner funnel, to recover the encapsulated aluminum-zirconium salt. Example 23 300 grams of a polydimethylsiloxane fluid having a viscosity of 50 mm²/s (centistokes) and 11.8 grams of stearic acid were combined in a 1 L round bottom flask equipped with a paddle-blade agitator, a water cooled condenser and a 250 ml round bottom receiver and heated to approximately 70°C. 300 grams of aqueous Aluminum-Zirconium Tetrachlorhydrex-Gly (35% solids) was added to the stearic acid solution, with agitation. The mixture was heated for approximately 1.5 hours, while distilling off the water, maintaining a temperature around 100°C. The reaction was stopped when no more water was observed to be distilling off. The mixture was vacuum filtered ( ∼ 80°C) using a Buchner funnel, to recover the encapsulated aluminum-zirconium salt. The particles were yellow. Example 24 150 grams of a polydimethylsiloxane fluid having a viscosity of 10 mm²/s (centistokes) and 6.3 grams of stearic acid were combined in a 500 ml round bottom flask equipped with a paddle-blade agitator, a water cooled condenser an a 250 ml round bottom receiver and heated to approximately 75°C. 150 grams of aqueous Aluminum-Zirconium Tetrachlorhydrex-Gly (35% solids) was added to the stearic acid solution, with agitation. The mixture was heated for approximately 3 hours, while distilling off the water, maintaining a temperature around 115°C. The reaction was stopped when the pot temperature reached approximately 135°C. and no more water was observed to be distilling off. The mixture was vacuum filtered ( ∼ 80°C.) using a Buchner funnel, to recover the encapsulated aluminum-zirconium salt. Example 25 150 grams of a mixture comprised of octamethylcyclotetrasiloxane and decamethylcyclopentasiloxane (cyclomethicone) and 6.3 grams of stearic anhydride were combined in a 500 ml round bottom flask equipped with a paddle-blade agitator, a water cooled condenser and a 250 ml round bottom receiver. The mixture was heated to 85°C. 150 grams of aqueous Aluminum-Zirconium Tetrachlorhydrex-Gly (35% solids) was added to the stearic anhydride solution, with agitation. The mixture was heated for approximately 1.5 hours, while distilling off the water, maintaining a temperature around 106°C. The reaction was stopped when the pot temperature reached approximately 127°C. The mixture was vacuum filtered ( ∼ 85°C.) using a Buchner funnel, to recover 50.07 grams encapsulated aluminum-zirconium salt. Example 26 150 grams of a mixture comprised of octamethylcyclotetrasiloxane and decamethylcyclopentasiloxane and 6.6 grams of stearoyl chloride were combined in a 500 ml round bottom flask equipped with a paddle-blade agitator, a water cooled condenser and a 250 ml round bottom receiver. The mixture was heated to 85°C. 150 grams of aqueous Aluminum-Zirconium Tetrachlorhydrex-Gly (35% solids) was added to the stearoyl chloride acid solution, with agitation. The mixture was heated for approximately 2 hours, while distilling off the water, maintaining a temperature around 105°C. The reaction was stopped when the pot temperature reached approximately 130°C. The mixture was vacuum filtered ( ∼ 85°C.) using a Buchner funnel, to recover 57.34 grams of encapsulated aluminum-zirconium salt. Example 27 Four experiments were conducted to determine the effect of agitation rate on particle size. In the experiments, 150 grams of a mixture comprised of octamethylcyclotetrasiloxane and decamethylcyclopentasiloxane and 6.3 grams of stearic acid were combined in a 500 ml round bottom flask equipped with a paddle-blade agitator, a water cooled condenser and a 250 ml round bottom receiver and heated to 75°C. 150 grams of aqueous Aluminum-Zirconium Tetrachlorhydrex-Gly (35% solids), was added to the stearic acid solution, with agitation. The mixture was heated while distilling off the water. The agitation during the distillation was maintained at various levels given in Table 2. The reaction was stopped when there was no more water observed to be distilling off. The mixture was then vacuum filtered using a Buchner funnel, to recover the encapsulated aluminum-zirconium salt. The particle size of the resulting encapsulated aluminum-zirconium salts was measured using a Malvern 3600 EZ particle sizer. Results are given in Table 2. Agitation Speed Particle Size (microns) Distribution µm Average µm 150 113 to 262 199 200 125 to 270 199 400 25 to 270 130 650 7 to 65 27 Example 28 A suspension stick composition was produced by heating 55 parts of cyclomethicone and 20 parts of stearyl alcohol to 65°C with stirring. 2 parts of PPG-14 Butyl Ether was then added with continued stirring followed by 1 part of hydrogenated caster oil, 2 parts of talc and 20 parts of an encapsulated aluminum-zirconium salt produced as in Example 15. The mixture was cooled to 53°C. and cast into a stick. Example 29 An aerosol composition was produced by mixing 12 parts of an encapsulated aluminum-zirconium salt as produced in Example 15 with 10.5 parts of cyclomethicone and 2 parts of dimethicone. This mixture was loaded into an aerosol container and charged with 75.5 parts of propellant. Ccomparative Example 1 This experiment shows that it is necessary to have a carboxylate present for the salts to become encapsulated. 50 grams of a mixture comprised of octamethylcyclotetrasiloxane and decamethylcyclopentasiloxane was heated to 100°C. 25 grams of a 50% aqueous solution of Aluminum Chlorohydrate was slowly added while increasing agitation. The temperature of the mixture dropped to around 80°C. during the addition. The mixture was heated for approximately 15 minutes until the temperature reached 130°C. Further agitation was not possible. The mixture was then vacuum filtered (while hot), using a Buchner funnel, to recover the resulting product. The particles were large angular chunks that showed no signs of encapsulation.

Claims: An encapsulated aluminum salt composition comprising (I) an aluminum salt selected from the group consisting of aluminum halohydrates, aluminum nitrohydrate, and mixtures thereof, and aluminum-zirconium halohydrates and mixtures thereof; contained in a shell comprising (II) a carboxylate or mixture of carboxylates selected from carboxylates having the formula wherein R¹ is selected from the group consisting of a saturated or unsaturated, branched or linear alkyl group consisting of at least 2 carbon atoms and a substituted or unsubstituted phenyl group consisting of at least 6 carbon atoms; and Z is selected from the group consisting of the hydrogen atom, an alkali metal, and glyceryl. A method for producing encapsulated aluminum salt compositions comprising (A) mixing together (i) an aqueous aluminum salt selected from the group consisting of aluminum halohydrates, aluminum nitrohydrate and mixtures thereof, and aluminum-zirconium halohydrates and mixtures thereof; (ii) a non-water miscible hydrophobic liquid selected from the group consisting of low viscosity silicone fluids, paraffin oils, and-mixtures thereof; and (iii) a carboxylate selected from carboxylates having the formula wherein R¹ is selected from the group consisting of a saturated or unsaturated, branched or linear alkyl group consisting of at least 2 carbon atoms and a substituted or unsubstituted phenyl group consisting of at least 6 carbon atoms; and Z is selected from the group consisting of the hydrogen atom, an alkali metal, glyceryl and mixtures thereof; (B) heating the mixture of (A) to remove substantially all free water; and (C) recovering the encapsulated aluminum salt. An aerosol composition comprising (A) 1% to 25% by weight of the encapsulated aluminum halohydrate and/or nitrohydrate salt composition as claimed in claim 1; (B) 50 to 90% by weight of propellant; and (C) 5 to 15% by weight of an anhydrous carrier liquid. A stick composition comprising (A) 1% to 25% by weight of the encapsulated aluminum halohydrate and/or nitrohydrate salt composition as claimed in claim 1; (B) 20 to 65% by weight of a carrier fluid; and (C) 5 to 30% by weight of a waxy gellant. An roll-on composition comprising (A) 1% to 25% by weight of the composition as claimed in claim 1; and (B) 60 to 90% by weight of a carrier liquid. An aerosol composition comprising (A) 1% to 20% by weight of the encapsulated aluminum-zirconium salt composition as claimed in claim 1; (B) 50 to 90% by weight of propellant; and (C) 5 to 15% by weight of an anhydrous carrier liquid. A stick composition comprising (A) 1% to 20% by weight of the encapsulated aluminum-zirconium salt composition as claimed in claim 1; (B) 20 to 65% by weight of a carrier fluid; and (C) 5 to 30% by weight of a gellant. An roll-on composition comprising (A) 1% to 20% by weight of the composition as claimed in claim 1; and (B) 60 to 90% by weight of a carrier liquid.

Inventors: CONWAY LORI JEAN, KATSOULIS DIMITRIS ELIAS, SCHULZ WILLIAM JAMES JR, SMITH JANET MARY, CONWAY, LORI JEAN, KATSOULIS, DIMITRIS ELIAS, SCHULZ, WILLIAM JAMES, JR., SMITH, JANET MARY
Applicants: DOW CORNING, DOW CORNING CORPORATION
Application year: 1991
Main classification: A61K7
IPC codes: A61K8, A61Q15