Preparation of silicone microemulsions

Abstract

A mechanical method of making an oil-in-water microemulsion containing (A) a polysiloxane and (B) an inert fluid selected from an inert siloxane fluid and an inert organic fluid, where the average emulsion particle size is between 1 and 140 nanometers, is disclosed. The process involves the following steps: i) preparing an oil phase comprising a polysiloxane containing mixture by the polymerization of silane or siloxane containing monomers and/or oligomers in the presence of an inert fluid, a suitable catalyst and optionally an end-blocking agent; and ii) where required quenching the polymerization process; wherein the inert fluid is substantially retained within the resulting polysiloxane containing mixture; iii) if required, mixing one or more surfactants into the oil phase; iv) adding water to the oil phase, followed by applying agitation or shear to the mixture to arrive at an oil-in-water microemulsion; v) optionally diluting the oil-in-water microemulsion by adding more water.

Claims

1. A method of making an oil-in-water microemulsion containing (A) a polysiloxane and (B) a non-volatile inert fluid having viscosity of from 0.65 mPa.Math.s to 10000 mPa.Math.s at 25 C. and selected from a non-volatile inert siloxane fluid and a non-volatile inert organic fluid, where the average emulsion particle size is between 1 and 140 nanometers, said method comprising the steps of: a) preparing an oil phase comprising a polysiloxane containing mixture by the polymerisation of silane or siloxane containing monomers and/or oligomers in the presence of the non-volatile inert fluid (B), a suitable catalyst, and optionally an end-blocking agent; b) optionally quenching the polymerisation; wherein the non-volatile inert fluid (B) is substantially retained within the resulting polysiloxane containing mixture in an amount of from 5% to 70% w/w; c) optionally mixing one or more surfactants into the oil phase; d) adding water to the oil phase; e) applying agitation or shear to the polysiloxane containing mixture to arrive at an oil-in-water microemulsion; and f) optionally diluting the oil-in-water microemulsion by adding more water.

2. The method in accordance with claim 1, wherein the polysiloxane (A) is prepared via a polymerisation process selected from the group of polycondensation, chain extension, polyaddition, and ring opening.

3. The method in accordance with claim 1, wherein the polysiloxane (A) after polymerization contains less than 0.5% by weight of siloxanes of boiling point lower than 250 C.

4. The method in accordance with claim 1, wherein the one or more surfactants are present in the oil phase and wherein the catalyst is one of the one or more surfactants used for emulsification.

5. The method in accordance with claim 1, wherein the oil phase has a viscosity of from 100 mPa.Math.s to 1000000 mPa.Math.s at 25 C.

6. The method in accordance with claim 1, wherein the polysiloxane (A) comprises siloxy units having the formula
R.sub.(3a)R.sup.1.sub.aSiO[(R.sub.2SiO).sub.b]SiR.sub.(3a)R.sup.1.sub.a wherein each R is the same or different and is an alkyl group containing 1 to 8 carbon atoms, a substituted alkyl group containing 1 to 6 carbon atoms, or a phenyl group; R.sup.1 is a hydroxy group, a hydrolysable group, or an unsaturated organic group; a is zero or 1; and b is an integer equal to a value of at least 200.

7. The method in accordance with claim 6, wherein the polysiloxane (A) comprises one or more substituted alkyl groups, each of which groups contain at least one polar group attached to silicon through a silicon-carbon bond or a silicon-oxygen-carbon bond.

8. The method in accordance with claim 6, wherein b is equal to a value of at least 1500.

9. The method in accordance with claim 6, wherein the polysiloxane (A) additionally comprises one or more [RSiO.sub.3/2] units and/or [SiO.sub.4/2] units.

10. An oil-in-water microemulsion obtained in accordance with the method of claim 1.

11. An oil-in-water microemulsion containing: (A) a polysiloxane; and (B) a non-volatile inert fluid; wherein the average particle size of the emulsion is between 1 and 140 nanometers.

12. The oil-in-water microemulsion in accordance with claim 10, wherein the non-volatile inert fluid (B) is selected from the group of a trialkylsilyl terminated polydialkylsiloxane having a viscosity of from 0.65 mPa.Math.s to 10000 mPa.Math.s at 25 C.; a cyclic siloxane having from 2 to 20 silicon atoms; a polyisobutylene; an alkylbenzene, a mineral or white oil, an aliphatic or aromatic ester and ether; a glyceride; a fatty alcohol and a natural oil or a natural oil derivative.

13. The oil-in-water microemulsion according to claim 10, wherein the polysiloxane (A) contains one or more siloxane units having SiC-bonded groups containing basic nitrogen.

14. The oil-in-water microemulsion according to claim 10, wherein the polysiloxane (A) contains one or more siloxane units having SiC-bonded groups containing a quaternary ammonium group.

15. A cosmetic or personal care product comprising the oil-in-water microemulsion obtained in accordance with the method of claim 1.

16. The oil-in-water microemulsion in accordance with claim 11, wherein the non-volatile inert fluid (B) is selected from the group of a non-volatile trialkylsilyl terminated polydialkylsiloxane having a viscosity of from 0.65 mPa.Math.s to 10,000 mPa.Math.s at 25 C.; a cyclic siloxane having from 2 to 20 silicon atoms; a polyisobutylene; an alkylbenzene, a mineral or white oil, an aliphatic or aromatic ester or ether; a glyceride; a fatty alcohol and a natural oil or a natural oil derivative.

17. The oil-in-water microemulsion according to claim 11, wherein the polysiloxane (A) contains one or more siloxane units having SiC-bonded groups containing basic nitrogen.

18. The oil-in-water microemulsion according to claim 11, wherein the polysiloxane (A) contains one or more siloxane units having SiC-bonded groups containing a quaternary ammonium group.

19. A method of making an oil-in-water microemulsion containing (A) a polysiloxane and (B) a non-volatile inert fluid, where the average emulsion particle size is between 1 and 140 nanometers, said method comprising the steps of: a) preparing an oil phase comprising a polysiloxane containing mixture by the polymerisation of silane or siloxane containing monomers and/or oligomers in the presence of the non-volatile inert fluid (B) which is unreactive towards any other constituents, has a viscosity of from 0.65 mPa.Math.s to 10000 mPa.Math.s at 25 C., and is selected from an organopolysiloxane extender and/or plasticiser, an organic extender and/or plasticiser, and a cyclic siloxane comprising between 2 and 20 silicon atoms, a suitable catalyst, and optionally an end-blocking agent; b) optionally quenching the polymerisation; wherein the non-volatile inert fluid (B) is substantially retained within the resulting polysiloxane containing mixture in an amount of from 5% to 70% w/w; c) optionally mixing one or more surfactants into the oil phase; d) adding water to the oil phase; e) applying agitation or shear to the polysiloxane containing mixture to arrive at an oil-in-water microemulsion; and f) optionally diluting the oil-in-water microemulsion by adding more water.

20. The method in accordance with claim 19, wherein the non-volatile inert fluid (B) is selected from the group of a trialkylsilyl terminated polydialkylsiloxane; a cyclic siloxane having from 3 to 20 silicon atoms; a polyisobutylene; an alkylbenzene, a mineral or white oil, an aliphatic or aromatic ester, an aliphatic or aromatic ether; a glyceride; a fatty alcohol, a natural oil, and a natural oil derivative.

21. The method in accordance with claim 1, wherein the non-volatile inert fluid (B) is substantially retained within the resulting polysiloxane containing mixture in an amount of from 5% to 60% w/w.

22. The method in accordance with claim 21, wherein the non-volatile inert fluid (B) is substantially retained within the resulting polysiloxane containing mixture in an amount of from 5% to 50% w/w.

23. The method in accordance with claim 19, wherein the non-volatile inert fluid (B) is substantially retained within the resulting polysiloxane containing mixture in an amount of from 5% to 60% w/w.

24. The method in accordance with claim 23, wherein the non-volatile inert fluid (B) is substantially retained within the resulting polysiloxane containing mixture in an amount of from 5% to 50% w/w.

Description

EXAMPLES

(1) The following Examples are provided so that one skilled in the art will more readily understand the disclosure. Unless otherwise indicated, all parts and percents are by weight and all viscosities are at 25 C. Viscosity measurements of the polymer products were carried out using a Brookfield Viscometer, spindle 6, at a speed of 10 rpm.

Example 1

(2) Part A

(3) In a 3 litre three-neck round bottom flask equipped with a stir rod attached with a 11 cm Teflon paddle, a thermocouple, and a condenser was mixed 986.4 grams of decamethylcyclopentasiloxane, 8.4 grams of a trimethylsiloxy-terminated methylhydrogensiloxane of 60 degrees of polymerization, 5.10 grams of hexamethyldisiloxane and 100 grams of a C12-15 alkylbenzoate. The mixture was henceforth covered under nitrogen blanket. To the mixture was added 1 gram of trifluoromethanesulfonic acid via a syringe. The content was heated to and held at 65 C. under constant stir at 300 RPM for four hours. 40 grams of sodium bicarbonate (NaHCO.sub.3) was then added and the mixture was cooled to 20 C. The mixture was filtered using a 10 micron filter paper to remove NaHCO.sub.3 and was then heated to 120 C. and stripped under vacuum to remove volatile cyclic siloxane. This resulted in a clear mixture containing 90 wt % of a siloxane polymer of 348 degrees of polymerization, as measured by .sup.29Si NMR, and 10 wt % of C12-15 alkylbenzoate which was the inert fluid.

(4) Part B

(5) In a 1 litre three-neck round bottom flask equipped with a stir rod attached with a 11 cm Teflon paddle, a thermocouple, a condenser was mixed 195 grams of the product from Part A, 22.2 grams of a poly((ethylene oxide).sub.10(propylene oxide).sub.4) monoallyl ether, 10 grams of isopropanol and 0.1 gram of sodium acetate. The mixture was stirred at 300 RPM and heated to 70 C. under nitrogen blanket. To the mixture was added 0.22 gram of a Dow Corning trade secret platinum complex containing 1% of elemental platinum. The reaction was exothermic. The mixture was kept at 84 C. under constant stir for 1 hour and 15 minutes and was then cooled to 40 C. A vacuum was applied to strip off isopropanol in the mixture. The final product contains 91 wt % of a trimethylsiloxy-terminated polydimethyl methyl(propyl(poly(EO)(PO)acetate)siloxane and 9 wt % of C12-15 alkylbenzoate which was the inert fluid.

(6) Part C

(7) To 12 grams of the product from Part B was added 2.5 grams of Genapol UD050, 3.5 grams of Genapol UD110 and 5.0 grams of water. The mixture was mixed in a SpeedMixer (DAC 150 FVZ) at 3500 RPM for 30 seconds. 12 grams of water was then added in two portions to the mixture and each addition was followed by the same mixing procedure as before. This resulted in a clear (transparent) oil-in-water microemulsion having a mono-modal particle size distribution centered around 30.8 nanometers diameter with 90% of the particles falling below 46.7 nanometers, as measured by a Nanotrac particle sizer in volume mode.

(8) Part D

(9) To 10 grams of the product from Part B was added 2.0 grams of Hostapur SAS-30 (30% active surfactant), 3.0 grams of Genapol UD050 and 3.5 grams of water. The mixture was mixed in a SpeedMixer (DAC 150 FVZ) at 3500 RPM for 30 seconds. 12 grams of water was then added in two portions to the mixture and each addition was followed by the same mixing procedure as before. This resulted in a water clear (transparent) oil-in-water microemulsion having a mono-modal particle size distribution centered around 15.4 nanometers diameter with 90% of the particles falling below 25.1 nanometers, as measured by a Nanotrac particle sizer in volume mode.

(10) In this example, a polysiloxane was polymerized in the presence of an organic inert fluid (C12-15 alkylbenzoate) via ring open/equilibration (Part A) followed by polyaddition (Part B). The resultant polymer mixture retaining the inert fluid was then emulsified into a microemulsion using non-ionic surfactant (Part C) and a microemulsion using anionic surfactant (Part D). The benefit of using the inert fluid in this example was to keep the viscosity of the product in Part A low enough to ease the strip of the volatiles as well as for the ease in emulsification, since the polysiloxane had a high degree of polymerization hence a high viscosity. Furthermore, the inert fluid itself can bring added performance benefit as it is often used as an emollient or moisturizer in cosmetic products.

Example 2

(11) A mixture of 80 g dimethyl hydroxyl terminated polydimethylsiloxane having a viscosity of 70 mPa.Math.s at 25 C., 20 g of Hydroseal G 250H, 3 g of octanoic acid and 6 g of 3-aminopropylmethyldiethoxysilane were mixed with a magnetic stirrer for 24 hours at room temperature (RT). 9 g Lutensol T08 was added to 15 g of the mixture described above and mixed for 20 s at 3000 rpm in a Hausschild dental mixer. An additional 1.0 g of water was added and mixing repeated under the same conditions. Further additions of water and subsequent mixing were carried out until 26 g water had been added in total, yielding a clear gel with 30% active content. Further dilution in water to 3% active content yielded a clear slightly bluish emulsion which had a particle size of D(v, 0.1) nm=61.1, D(v, 0.5) nm=100.2 (Measured with a Nanotrac particle sizer in the volume mode).

Example 3

(12) A mixture of 80.0 g dimethyl hydroxyl terminated polydimethylsiloxane having a viscosity of 70 mPa.Math.s at 25 C., 20 g of Hydroseal G 250H, 3.1 g of octanoic acid and 6.0 g of 3-aminopropylmethyldiethoxysilane were mixed with a magnetic stirrer for 24 hours at a temperature of 50 C. The resulting homogenous mixture had a viscosity of 7400 mPas (using a Brookfield RVDV-I+ viscometer Spindle 5, at a speed of 20RPM) at 25 C.

(13) 6.1 g Lutensol T08 was mixed into 15 g of the resulting mixture described above and mixed for 20 s at 3000 rpm in a Hausschild dental mixer. An additional 1.1 g of water was added and mixing repeated under the same conditions. Further sequential additions of water took place with subsequent mixing in each instance until 26 g water had been added in total, yielding a microemulsion with 30% active content which had a particle size of D(v, 0.1) nm=63.3, D(v, 0.5) nm=94.6 (Measured using a Nanotrac particle sizer in the volume mode).

Example 4

(14) A mixture of 80.0 g dimethyl hydroxyl terminated polydimethylsiloxane having a viscosity of 70 mPa.Math.s at 25 C., 20 g of Isopar L (supplied by Exxon), 3.0 g of octanoic acid and 6.0 g of 3-aminopropylmethyldiethoxysilane were mixed with a magnetic stirrer for 24 hours at 50 C. The resulting homogenous mixture had a viscosity of 370 mPa.Math.s (Brookfield RVDV-I+ viscometer, Spindle 4, speed 100 RPM) at 25 C.

(15) 6.0 g Lutensol T08 was mixed into to 15.0 g of the resulting mixture described above for 20 s at 3000 rpm in a Hausschild dental mixer. An additional 1.1 g of water was added and mixing repeated under the same conditions. Further sequential additions of water took place with subsequent mixing in each instance until 26.2 g water had been added in total, yielding a micromeulsion with approx. 30% active content. which had a particle size of D(v, 0.1) nm=75.5, D(v, 0.5) nm=108.5 (Measured with a Nanotrac particle sizer in the volume mode).

Example 5

(16) In a SpeedMixer (DAC 150 FVZ) was mixed 18 g of a hydroxyl terminated polydimethylsiloxane having a viscosity of 90 centiPoise (cP) (90 mPa.Math.s), 5 g of a mixture consisting of 73% 3-(trimethoxysilyl)propyldimethyloctadecylammonium chloride, 15% chloropropyltrimethoxysilane and 12% dodecyl alcohol, and 2 g mineral oil (Hydroseal G 250H) until homogeneous. The homogeneous mixture had a viscosity of 80 cP (80 mPa.Math.s). To this homogeneous mixture was added 0.3 g 1,1,3,3-tetramethylguanidine and 0.2g octanoic acid and again mixing took place until homogeneous. The resulting mixture was stored at 50 C. for 20 hours to allow polymerization, and was then cooled down to room temperature. The viscosity of the polymerized mixture was 2,534 cP (2,534 mPa.Math.s).

(17) To 19 g of the above polymerized mixture was added 2.34 g of undeceth-5 (Genapol UD050) and 5.53 g undeceth-11 (Genapol UD110), and the content was spun in a SpeedMixer at 3500 RPM for 22 sec. 3.0 g water was added, and the mixture was stirred by a spatula forming a clear to hazy mixture, and the mixture was then spun under the same condition. Two additional portions of water, 3.0 g each, were added, each time followed by spin under the same condition. The mixture became clear and highly viscous. An additional 21 g of water was added followed by spin under the same condition, arriving at a clear aqueous microemulsion with a slight bluish haze. The microemulsion had a mono-modal particle size distribution with a median particle diameter of 37.3 nanometers and 90% of the particles smaller than 57.0 nanometer, as measured using a Nanotrac (UPA150) particle sizer in the volume mode.

Comparative Example 1

(18) The procedure of Example 1 Part C was repeated except that 12 grams of C12-15 alkylbenzoate was substituted in place of the product from Part B of Example 1. This resulted in an opaque white emulsion having a mono-modal particle size distribution centered around 371 nm.

Comparative Example 2

(19) The procedure of Example 1 Part D was repeated except that 10 grams of C12-15 alkylbenzoate was substituted in place of the product from Part B of Example 1. This resulted in an opaque white emulsion having a mono-modal particle size distribution centered around 294 nm.

Comparative Example 3

(20) The emulsification part of Example 5 was repeated except that 19 grams of mineral oil (Hydroseal G 250H) was substituted in place of the polymerized siloxane mixture containing the mineral oil as the inert fluid in that example. This did not result in any emulsion as the oil and water remained separated after emulsification attempt.

(21) These comparative examples illustrate that it is extremely difficult, if not impossible, to produce microemulsions from the majority, if not all, of these inert fluids on their own.