Sanitizing hand cleanser comprising an organic alcohol and silicone based materials

A sanitizing hand cleanser is prepared which includes about 70 wt. % anhydrous ethanol (3% isopropyl alcohol), about 18.6 wt. % Dow Corning® 345 Fluid (cyclomethicone), about 4.5 wt. % isopropyl myristate, about 1.5 wt. % lactic acid, about 1.5 wt. % sodium lactate (40% active), about 1.3 wt. % Dow Corning® 749 (cyclomethicone and trimethylsiloxysilicate product), about 0.6 wt. % Dow Methocel® OS (methylated cellulose), and about 2.0 wt. % Cabosil M5 fumed silica, commercially available from Cabot Corporation. The product is prepared by mixing the anhydrous ethanol, the 345 Fluid, the isopropyl myristate, the lactic acid, the sodium lactate, and the Dow Corning 749 at ambient temperature in a batch mix tank fitted with at least one agitator or mixing blade until the alcohol mixture is well mixed. Then about 30% of the alcohol mixture is removed to a separate mixing vessel fitted with mixing blades and the Methocel® is added, with mixing, until the mixture thickens slightly. The fumed silica is then added to the Methocel® mixture to cause the mixture to thicken further. The fumed silica/Methocel® mixture is then combined with the remaining alcohol mixture, with continuous mixing, until the fumed silica mixture is completely dissolved in the alcohol mixture. The resulting product has a pH of about 4.5 and has a viscosity of about 350 cp at about 25° C.

A sanitizing hand cleanser is prepared which includes about 77.6 wt. % anhydrous ethanol (3% isopropyl alcohol), about 15.5 wt. % Dow Corning® 345 Fluid (cyclomethicone), about 1.5 wt. % isopropyl myristate, about 3.6 wt. % sodium lactate (40% active), about 1.0 wt. % Dow Corning® 749 (cyclomethicone and trimethylsiloxysilicate product), about 0.5 wt. % Dow Methocel® OS, and about 0.3 wt. % fragrance. The product is prepared by mixing the anhydrous ethanol, the 345 Fluid, the isopropyl myristate, the sodium lactate, the Dow Corning 749 and the fragrance at ambient temperature in a batch mix tank fitted with at least one agitator or mixing blade until the alcohol mixture is well mixed. Then about 30% of the alcohol mixture is removed to a separate mixing vessel fitted with mixing blades and the Methocel® is added, with mixing, until the mixture thickens slightly. The Methocel® mixture is then combined with the remaining alcohol mixture, with continuous mixing, until the Methocel® mixture is completely dissolved in the alcohol mixture. The resulting product has a pH of about 4.3 and has a viscosity of about 340 cp at about 25° C.

A sanitizing hand cleanser is prepared which is identical to the product of Example 2 except that about 1.5 wt. % of tea tree oil is substituted for about 1.5 wt. % anhydrous ethanol (3% isopropyl alcohol). The product is prepared as in Example 2 with the tea tree oil added in the alcohol mixture. The resulting product has a pH of about 4.4 and has a viscosity of about 360 cp at about 25° C.

A sanitizing hand cleanser is prepared which is identical to the product of Example 2 except that about 1.8 wt. % of hemp oil is substituted for about 1.8 wt. % anhydrous ethanol (3% isopropyl alcohol). The product is prepared as in Example 2 with the hemp oil added in the alcohol mixture. The resulting product has a pH of about 4.3 and has a viscosity of about 350 cp at about 25° C.

A sanitizing hand cleanser is prepared which is identical to the product of Example 2 except that about 1.0 wt. % of tea tree oil and about 0.5 wt. % of hemp oil is substituted for about 1.5 wt. % anhydrous ethanol (3% isopropyl alcohol). The product is prepared as in Example 2 with the tea tree oil and hemp oil added in the alcohol mixture. The resulting product has a pH of about 4.3 and has a viscosity of about 365 cp at about 25° C.

Antimicrobial Performance Studies:

Antibacterial efficacy of the hand sanitizing cleansers can be evaluated by a variety of known procedures. For example, a minimum inhibitory concentration study may be used to determine the lowest concentration of the cleanser that inhibits growth of a microorganism or a rapid germicidal study may be used to measure the ability of the cleanser to rapidly reduce a known population of microorganisms. Such studies can be conducted using commonly available bacteria and fungi as are listed in Table I.

The minimum inhibitory concentration (MIC) is the lowest concentration of an antimicrobial agent that inhibits growth of a microorganism. Serial dilutions of the antimicrobial test material are made in broth or agar and then a standardized concentration of the organism is plated onto the agar containing the diluted test material. A variety of organisms are tested against the article to determine the greatest dilution of the article possible while still maintaining antimicrobial efficacy.

Specifically, the product of Example 2 (“Product 2”) is tested for minimum inhibitory concentration (MIC) following a procedure wherein a 1:2 dilution of a test material, by weight, is prepared in Mueller-Hinton Broth or a Brain Heart Infusion Broth. A 200 μL aliquot of the dilution is added to the first well in a row of a microtiter plate. Dilutions of the product are then made starting from the first well with the wells containing dilutions of 1:2, 1:4, 1:8, 1:10, 1:20, 1:50, 1:80, 1:100, 1:150 and 1:200 of the test material. Bacterial and media control wells are also included.

The bacterial organism of interest is scraped from a culture plate and resuspended in phosphate buffered saline solution to an approximate density of 1.0×10 5 cells. An inoculum of approximately 5×10 4 CFU (colony forming units) of each test organism is added to the test wells in a row of the plate and mixed. The plate is incubated at a temperature of 37±2° C. for about 23 hours. Table H summarizes the microbial growth in the test wells in terms of showing growth (+) or showing no growth (0). The MIC is considered to be the lowest dilution in which bacterial growth is completely inhibited in duplicate trials.

Rapid Germicidal Studies

The rapid germicidal studies are used to measure the ability of an antibacterial agent to rapidly reduce a known population of microorganisms. An aliquot of the antibacterial test material is contacted with a known concentration of test bacteria or fungi for a predetermined period of time. The test material is then neutralized, the concentration of the surviving microorganisms is determined, and the efficacy of the antibacterial agent is calculated based on the percentage of microorganisms that did not survive the expose to the antibacterial agent.

For example, the product of Example 2 (“Product 2”) is evaluated for rapid germicidal activity using a protocol wherein a 5 mL aliquot of undiluted Product 2 is placed in a sterile glass jar at 25±1° C. and a 0.5 mL sample of a selected microorganism broth culture yielding an approximate microorganism dilution of about 108 CFU/mL is mixed into the antibacterial material aliquot. After waiting a prescribed time (“exposure time”), 45 mL of a neutralizer solution is added to the glass jar and stirred for 60 seconds. A 1 mL aliquot is removed from the jar—having a microorganism dilution of about 10 −1 - and 10-fold serial dilutions are made to reach a dilution of about 10 −6 . The dilutions are plated in duplicate using a Pour Plate Technique. The plates are inverted and incubated at 35±2° C. for 48±2 hours. Following incubation, the colony forming units per mL (CFU/mL) for surviving organisms are counted and compared to the starting populations. Control samples are included for each organism and exposure time following essentially the same procedure except that the Product 2 is not added in the initial step of the procedure. Table III lists microorganisms for use in the Rapid Germicidal Study, the number of colony forming units per mL for the controls and the test samples (reported in replicate), and the efficacy of the Product 2 as determined by percent reduction in organism count and the log 10 reduction.

From a reading of the above, one with ordinary skill in the art should be able to devise variations to the inventive features. For example, other additives may be included in the formulation to increase consumer acceptance, such as dyes, colorants, skin-softening agents, skin-protecting agents, such as sunscreening materials, and other silicone or non-silicone compounds or solvents that may modify the drying characteristics of organic alcohols or change the tactile feel and dryness caused by high alcohol containing systems. These and other variations are believed to fall within the spirit and scope of the attached claims.