Silica particles, manufacturing method thereof and resin particles

1. Silica particles having a volume average particle size of from about 100 nm to about 500 nm, an average circularity degree of from about 0.5 to about 0.85, and an average value of the ratios of circle equivalent diameters Da of the silica particles obtained by a flat image analysis to maximum heights H of the silica particles obtained by a stereoscopic image analysis of more than 1.5 and less than 1.9.

2. The silica particles according to claim 1 , wherein surfaces thereof are hydrophobized by a hydrophobizing agent.

3. The silica particles according to claim 2 , wherein the hydrophobizing agent is a known organic silicon compound having an alkyl group.

4. The silica particles according to claim 3 , wherein the hydrophobizing agent is hexamethyldisilazane.

5. The silica particles according to claim 2 , wherein the amount of the hydrophobizing agent is from about 1 mass % to about 100 mass % with respect to the silica particles.

6. A method of manufacturing the silica particles according to claim 1 , the method comprising:

preparing an alkali catalyst solution in which an alkali catalyst is included in a solvent that contains alcohol;

supplying, until the supply amount of tetraalkoxysilane reaches from about 0.002 mol/mol to about 0.008 mol/mol with respect to the amount of the alcohol in the preparation of the alkali catalyst solution, the tetraalkoxysilane and the alkali catalyst to the alkali catalyst solution;

stopping the supply of the tetraalkoxysilane and the alkali catalyst for a period of time of from about 0.5 min to about 10 min after the supply of the tetraalkoxysilane and the alkali catalyst; and

supplying the tetraalkoxysilane and the alkali catalyst to the alkali catalyst solution after the supply stop.

7. The method according to claim 6 , wherein the alkali catalyst is ammonia.

8. The method according to claim 6 , wherein the concentration of the alkali catalyst is from about 0.6 mol/L to about 0.85 mol/L.

9. The method according to claim 6 , wherein the tetraalkoxysilane includes at least one of tetramethoxysilane and tetraethoxysilane.

10. Resin particles having surfaces to which the silica particles according to claim 1 are attached.

11. Resin particles having surfaces to which the silica particles according to claim 1 , having surfaces hydrophobized by a hydrophobizing agent, are attached.