Hydrophobic silica particles, use of same, and method for producing hydrophobic silica particles
The present invention relates to hydrophobic silica particles including silica particles each being impregnated with a higher alcohol having 19 or more carbon atoms, and having a binding degree of the higher alcohol to the silica particles of 70% or more measured by the following measuring method: the measuring method: 1 g of the hydrophobic silica particles is dispersed in 10 mL of tetrahydrofuran, and after maintaining the dispersed state for 5 minutes, a filtered residue is washed with 20 mL of tetrahydrofuran and 20 mL of hexane and dried, and a ratio, represented by Equation (1), of a carbon content of the hydrophobic silica particles after washing to a carbon content of the hydrophobic silica particles before washing is defined as the binding degree, binding degree (%)=carbon content (%) of hydrophobic silica particles after washing/carbon content (%) of hydrophobic silica particles before washing×100 (1).
1 . A composition of hydrophobic silica particles comprising hydrophobic silica particles impregnated with a higher alcohol having 19 or more carbon atoms, the composition of hydrophobic silica particles having:
an average particle diameter of from 2 μm to 7.2 μm,
an oil absorption value of from 20 mL/100 g to 400 mL/100 g,
a circularity of 0.95 or more
an impregnation amount of the higher alcohol of 1.0 μmol/m 2 or more, and
a binding degree of the higher alcohol to the silica particles of 70% or more;
wherein the binding degree of the higher alcohol to the silica particles is measured by the following measuring method:
1 g of the hydrophobic silica particles is dispersed in 10 mL of tetrahydrofuran, and after maintaining the dispersed state for 5 minutes, a filtered residue is washed with 20 mL of tetrahydrofuran and 20 mL of hexane and dried, and a ratio, which is represented by Equation (1) shown below, of a carbon content of the hydrophobic silica particles after washing to a carbon content of the hydrophobic silica particles before washing is defined as the binding degree,
wherein the binding degree (%)=carbon content (%) of hydrophobic silica particles after washing/carbon content (%) of hydrophobic silica particles before washing×100 (1); and
wherein the hydrophobic silica particles are capable of forming a stable dispersion in a liquid paraffin phase.
2 . The composition of hydrophobic silica particles according to claim 1 , wherein a silica particle serving as a base material has a specific surface area of 5 m 2 /g to 1000 m 2 /g.
3 . The composition of hydrophobic silica particles according to claim 1 , having the binding degree of 80% or more.
4 . A cosmetic comprising the composition of hydrophobic silica particles according to claim 1 .
5 . The composition of hydrophobic silica particles according to claim 1 , wherein the higher alcohol having 19 or more carbon atoms is at least one selected from the group consisting of chimyl alcohol, arachidyl alcohol, octyldodecanol, ethylene glycol monostearate, stearic acid monoethanolamide, glycerol monostearate, selachyl alcohol, batyl alcohol, behenyl alcohol, decyltetradecanol, and 1-tetracosanol.
6 . A method for producing hydrophobic silica particles according to claim 1 , comprising:
heating silica particles each of which a higher alcohol having 19 or more carbon atoms is attached to at 160° C. or higher.
7 . The method for producing hydrophobic silica particles according to claim 6 , wherein
the silica particles each of which the higher alcohol having 19 or more carbon atoms is attached to are obtained by heating and mixing the higher alcohol having 19 or more carbon atoms and the silica particles substantially without using any solvent.