Patent ID: 8187351

Claim:
A sol of spinous inorganic oxide particles comprising: a solvent, and spinous inorganic oxide particles comprising spherical core particles and verrucous projections formed of a material containing silica on surfaces of the spherical core particles, the spinous inorganic oxide particles being dispersed in the solvent, and having a) a sphericity in a range from 0.8 to 1, b) a surface roughness SA1/SA2 in a range from 1.20 to 1.70, wherein SA1 indicates a specific surface area measured by the Sears method or the BET method and SA2 indicates a specific surface area converted from an average diameter (D2) measured by the image analysis method, and c) the average particle diameter (D2) measured by the image analysis method in a range from 12 to 40 nm, wherein the spinous inorganic oxide particles satisfy the following conditions: d) number of coarse particles with diameter of 800 nm or more is 1500 particles/mL (converted to 1% by weight of solid phase concentration) or below, and e) a coefficient of variation (CV value) is 7.0% or below, wherein the solvent is water, a zeta potential of the spinous inorganic oxide particles has a negative value when pH of the sol of spinous inorganic oxide particles is in the range from 4 to 6, and an absolute value of the zeta potential is 25 mV or more.