In-SITU process for making a small particle narrow distribution fatty acyl isethionate in oil composition
The invention relates to novel compositions and novel in-situ process for making small average particle size, narrow distribution FAI in oil. The process comprises preparing FAI; separately optionally heating oil; adding oil to FAI in a molten state; heating to defined temperature; and cooling the heated mixture at a defined, controlled rate which ensures proper size and distribution are met.
1. A process for making an oil continuous composition, the process comprising the steps of:
a) reacting HOR′SO 3 M,
where R′ is a divalent hydrocarbon radical having 2 to 4 carbons and M is an alkali metal cation,
with RCOOH, where R is a monovalent aliphatic radical having 7 to 24 carbons to produce RCOOR″SO 3 M,
said reactants being combined at a temperature of 20 to 25° C. and heated to 200° to 245° C.;
b) adding an oil selected from the group consisting of mineral oil, triglyceride oil, silicone oil and mixtures thereof, wherein said oil has optionally been heated from 20-25° C. to 80 to 130° C., to the heated reaction product of step (a) while still in a molten state;
c) continuing to heat a mixture of the product of (a) and oil of (b) at a temperature of 200 to 245° C. to form a liquid phase mixture of fatty acyl isethionate, unreacted fatty acid, unreacted isethionate, catalyst, if used, trace impurities, if any, and oil; and
d) cooling the resultant mixture at 0.5 to 5° C. per minute to below the solidification temperature of the fatty acyl isethionate.
2. A process according to claim 1 wherein triglyceride oil is added in step (b) and said triglyceride oil is soybean oil.
3. A process according to claim 1 wherein a catalyst is used in step (c).
4. A process according to claim 3 wherein said catalyst is zinc oxide.
5. A process according to claim 1 , wherein the process comprises a pH adjustment, to result in a pH of the resulting composition of between 3.0 and 6.5.
6. A process according to claim 1 , wherein the shear rate during step c) and/or d) is 10 to 1000 sec −1 .
7. An oil continuous composition obtainable by the process of claim 1 comprising fatty acyl isethionate particles which are not pre-aggregated having an average particle size of 100 microns or less and a particle size distribution defined by a span of less than 4.5;
said composition being free of fatty acid soap crystals.
8. A composition according to claim 7 comprising fatty acyl isethionate particles having an average particle size less than 75 microns.
9. A composition according to claim 7 , wherein the span is less than 4.
10. A composition according to claim 7 , wherein the fatty acid isethionate is sodium alkanoyl isethionate.
11. A composition according to claim 7 comprising 25 to 90% by wt. oil and 10 to 60% by wt. fatty acyl isethionate.
12. A composition according to claim 7 wherein said oil continuous composition is a non-aqueous composition.
13. A composition according to claim 7 having pH of 3.0 to 6.5.
14. The composition according to claim 13 , wherein the pH is 4.0 to 6.0.