Silicone surfactant, W/O emulsion composition, powder composition, and cosmetic/medical application thereof

1. A silicone surfactant comprising a co-modified organopolysiloxane represented by the following general formula (1):

wherein

R 1 is a monovalent hydrocarbon group having from 1 to 30 carbons, or is a hydrogen atom;

R 2 is a straight or branched monovalent hydrocarbon group having from 6 to 30 carbons;

Q is a hydrophilic group consisting of a polyoxyalkylene group represented by structural formula (2):

—(C 2 H 4 O) r —(C 3 H 6 O) s —R 3

wherein

R 3 is a hydrogen atom or an alkyl group having from 1 to 4 carbons,

r is a number in a range of 0 to 100,

s is a number in a range of 0 to 50, and

r+s is a number in a range of 3 to 100;

R is a group selected from R 1 , R 2 , and Q;

provided that, when n3=0, at least one R is Q;

(n1+n2+n3) is a number in a range of 40 to 75;

n1 is a number in a range of 1 to 65;

n2 is a number in a range of 1 to 20; and

n3 is a number in a range of 0 to 5.

2. The silicone surfactant of claim 1 , wherein the co-modified organopolysiloxane is represented by the following general formula (1-1):

wherein n1 is a number in a range of 2 to 55, n2 is a number in a range of 3 to 20, and n3 is a number in a range of 0.5 to 5.

3. The silicone surfactant of claim 2 , having more than 30 wt % of content of hydrocarbon group of R 2 having from 6 to 30 carbons, which is calculated by the weight ratio of R 2 to the total molecular weight of the co-modified organopolysiloxane.

4. The silicone surfactant of claim 1 , having more than 30 wt % of content of hydrocarbon group of R 2 having from 6 to 30 carbons, which is calculated by the weight ratio of R 2 to the total molecular weight of the co-modified organopolysiloxane.

5. An ingredient comprising the silicone surfactant according to claim 1 , wherein the ingredient is selected from the group consisting of an emulsifier, a surface treatment agent, a powder treatment agent, and a dispersant in a cosmetic composition or a medicament.

6. A water-in-oil (W/O) emulsion composition comprising:

(A) the silicone surfactant according to claim 1 ;

(B) water; and

(C) at least one oil agent.

7. A cosmetic composition or a medicament comprising the W/O emulsion composition according to claim 6 .

8. A method of adjusting transparency of the W/O emulsion composition according to claim 6 , said method comprising the steps of:

(i) independently mixing an aqueous phase including component (B) and an oil phase including component (A) and component (C);

(ii) adjusting a difference between refractive indexes at 25° C. of both phases so as to be less than or equal to 0.0020 units; and

(iii) emulsifying the aqueous phase into the oil phase.

9. A powder composition comprising:

(A) the silicone surfactant according to claim 1 ; and

(D) a powder or coloring agent.

10. The powder composition according to claim 9 , wherein component (D) is one or two or more selected from the group consisting of an inorganic pigment powder, an organic pigment powder, and a resin powder, having an average diameter in a range of 1 nm to 20 μm.

11. The powder composition according to claim 10 , further comprising (C) at least one oil agent.

12. The powder composition according to claim 9 , further comprising (C) at least one oil agent.

13. A cosmetic composition or a medicament comprising the powder composition according to claim 9 .

14. A preparation for external use comprising the silicone surfactant according to claim 1 .

15. The preparation for external use according to claim 14 , further defined as a cosmetic composition or a medicament.

16. A cosmetic composition or a medicament comprising the silicone surfactant according to claim 1 , wherein the cosmetic composition or the medicament is in a substantially water-free form.