Process of forming crystals for use in a personal care composition

Abstract

A method of making a stable detersive surfactant containing personal care composition comprising the steps of emulsifying a stabilizing agent in the presence of anionic surfactant to form an emulsion containing droplets having a particle size of from about 0.1 to about 10 um. These particles are then cooled to form a stabilizing premix at a rate of about 10 to about 1000 C/min to form crystals from the droplets, the crystals having a maximum dimension of about 0.1 to about 3 um. These crystals are then added to a detersive surfactant containing personal care composition to increase stability.

What is claimed is: 
     
         1 . A method of making a stable, detersive surfactant containing anti-microbial personal care composition comprising:
 (a) emulsifying from about 4% to about 30% of a stabilizing agent in the presence of from about 2% to about 30% of an anionic surfactant to form an emulsion at a temperature of about 5 to about 20° C. above the melting point of the stabilizing agent, to form an emulsion wherein
 (i) the stabilizing agent is ethylene glycol distearate; 
 (ii) the anionic surfactant is selected from the group consisting of an alkyl sulfate, an alkyl ether sulfate, and a combination thereof, and 
 (iii) the formed emulsion contains droplets having a particle size of about 0.1 to about 10 um; 
   (b) cooling the emulsion to form a stabilizing premix at a rate of about 10 to about 1000 C/min to a temperature of about 5° C. to about 30° C. below the melting point of ethylene glycol distearate to form crystals from the droplets, the crystals having a maximum dimension of about 0.1 to about 3 um and an aspect ratio of about 2 to about 1000; and   (c) adding the stabilizing premix to a detersive surfactant containing anti-microbial personal care composition.   
     
     
         2 . The method of  claim 1 , wherein the stabilizing premix comprises from about 4% to about 40% of the total anionic surfactant containing personal care composition. 
     
     
         3 . The method of  claim 1 , wherein the alkyl ether sulfate has a molar ethoxylation ratio of from about 0.5 to about 5; wherein the alkyl ether sulfate has an average of 0.5 to 5 ethoxylate units per alkyl unit. 
     
     
         4 . The method of  claim 1 , wherein the emulsification of the crystallizing agent employs an agitated tank, a static mixer, an orifice plate, a rotor/stator mill, high energy homogenizer, or combinations thereof. 
     
     
         5 . The method of  claim 1 , wherein the emulsion is created using a power density of from about 1 to about 1000 W/kg. 
     
     
         6 . The method of  claim 1 , wherein the stabilizing premix is added to the detersive surfactant containing personal care composition less than 24 hours after crystallization. 
     
     
         7 . The method of  claim 1 , wherein the viscosity of the stabilizing premix is from about 50 to about 20,000 cP when measured at a shear rate of 2/sec and a temperature of 25° C. 
     
     
         8 . The method of  claim 1 , wherein the cooling of the emulsion employs a heat exchanger in a single pass or recirculation process. 
     
     
         9 . The method of  claim 8 , wherein the heat exchanger is a scraped wall, plate and frame, or shell and tube heat exchanger. 
     
     
         10 . The method of  claim 1 , wherein the personal care composition contains an additional structuring agent selected from the group consisting of hydrogenated castor oil, polysaccharides, and combinations thereof. 
     
     
         11 . The method of  claim 1 , wherein the personal care composition contains detersive surfactants selected from the group consisting of anionic surfactants, zwitterionic surfactants, amphoteric surfactants, or combinations thereof. 
     
     
         12 . The method of  claim 1 , wherein both the stabilizing premix and the personal care composition comprise at least 2% of the same anionic surfactant. 
     
     
         13 . The method of  claim 1 , wherein the anti-microbial personal care composition is an anti-dandruff active and wherein the anti-dandruff active is zinc pyrithione. 
     
     
         14 . The method of  claim 1 , wherein less than 2% of the personal care composition separates to form a second phase at the top or bottom of the composition when 85 g of the personal care composition is placed in a sealed 4 cm diameter glass jar at 40° C. for 60 days. 
     
     
         15 . A method of making a stable, detersive surfactant containing personal care composition comprising:
 (a) emulsifying from about 4% to about 30% of a stabilizing agent in the presence of from about 2% to about 30% of an anionic surfactant and from about 0.05% to about 5% of an organic fatty alcohol or fatty acid to form an emulsion at a temperature of about 5 to about 20° C. above the melting point of the stabilizing agent, to form an emulsion wherein:
 (i) the stabilizing agent is ethylene glycol distearate; 
 (ii) the anionic surfactant is selected from the group consisting of an alkyl sulfate, an alkyl ether sulfate, and a combination thereof, and 
 (iii) the formed emulsion contains droplets having a particle size of about 0.1 to about 10 um; 
   (b) cooling the emulsion to form a stabilizing premix at a rate of about 10 to about 1000 C/min to a temperature of about to a temperature of about 5° C. to about 30° C. below the melting point of ethylene glycol distearate to form crystals from the droplets, the crystals having a maximum dimension of about 0.1 to about 3 um and an aspect ratio of about 2 to about 1000; and   (c) adding the stabilizing premix to a detersive surfactant containing personal care composition.   
     
     
         16 . The method of  claim 15 , wherein the organic fatty acid or alcohol has a carbon chain length of from about 8 to about 20. 
     
     
         17 . The method of  claim 15 , wherein the crystals have an aspect ratio of from about 2 to about 1000. 
     
     
         18 . The method of  claim 15 , wherein the emulsification of the crystallizing agent employs an agitated tank, a static mixer, an orifice plate, a rotor/stator mill, high energy homogenizer, or combinations thereof. 
     
     
         19 . The method of  claim 15 , wherein the cooling of the emulsion employs a heat exchanger in a single pass or recirculation process. 
     
     
         20 . The method of  claim 15 , wherein less than 2% of the personal care composition separates to form a second phase at the top or bottom of the composition when 85 g of the personal care composition is placed in a sealed 4 cm diameter glass jar at 40° C. for 60 days.