Process of forming crystals for use in a personal care composition
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.
1. A method of making a stable, detersive surfactant-containing antimicrobial personal care composition, said method comprising:
(a) emulsifying from about 4% to about 30% of a stabilizing agent in the presence of about 2% to about 30% of an anionic surfactant at a temperature of about 70° C. to about 75° C. to form an emulsion, wherein:
(i) the stabilizing agent is ethylene glycol distearate (EGDS),
(ii) the anionic surfactant is selected from the group consisting of an alkyl sulfate, an alkyl ether sulfate, or a combination thereof, and
(iii) the formed emulsion contains droplets having a particle size of about 0.1 to about 10 μm;
(b) cooling the emulsion of step (a) at a rate of about 10 to about 1000° C./minute to a temperature of about 25° C. to about 35° C. to form a stabilizing premix, wherein the stabilizing premix comprises crystals formed from the emulsion droplets, said crystals having a mean length of about 0.1 to about 3 μm and an aspect ratio of about 2 to about 1000; and
(c) adding the stabilizing premix of step (b) to a detersive surfactant-containing antimicrobial personal care composition.
2. The method of claim 1 , wherein the stabilizing premix comprises from about 4% to about 40% of the total detersive 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.
4. The method of claim 1 , wherein the emulsion 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 4 , wherein the high energy homogenizer is a sonolator.
6. The method of claim 1 , wherein the emulsion is created using a power density of from about 1 to about 1000 W/kg.
7. 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.
8. The method of claim 1 , wherein the viscosity of the stabilizing premix is from about 50 to about 20,000 cP.
9. The method of claim 1 , wherein the cooling of the emulsion employs a heat exchanger in a single pass or recirculation process.
10. The method of claim 9 , wherein the heat exchanger is a scraped wall, plate and frame, or shell and tube heat exchanger.
11. 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.
12. 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.
13. The method of claim 1 , wherein both the stabilizing premix and the personal care composition comprise at least 2% of the same anionic surfactant.
14. The method of claim 1 , wherein the anti-microbial personal care composition is an anti-dandruff active and wherein the anti-dandruff active is ZPT.
15. The method of claim 1 , wherein the personal care composition containing crystals separates less than 4 mm in about 30 days when 85 g of the anti-microbial personal care composition is placed in a 5 cm diameter jar at 40° C.