Patent ID: 8029761

Claim:
Surface-treated metal oxide particles comprising metal oxide particles selected from the group consisting of aluminum oxide particles and titanium oxide particles, surface-treated with an organic silicon compound such that chemical groups containing silicon atoms are attached to the surface of the metal oxide particles, wherein the chemical groups containing silicon atoms generate resonance signals with chemical shifts in a CP/MAS 29 Si NMR spectrum, wherein the chemical shifts are measured in ppm relative to tetramethylsilane standard, wherein resonance signals with chemical shifts in the range from −4 ppm to −33 ppm in the CP/MAS 29 Si NMR spectrum correspond to D sites and have an integrated area on the CP/MAS 29 Si NMR spectrum, wherein resonance signals with chemical shifts in the range from −33 ppm to −76 ppm in the CP/MAS 29 Si NMR spectrum correspond to T sites and have an integrated area on the CP/MAS 29 Si NMR spectrum, wherein resonance signals with chemical shifts in the range from −76 ppm to −130 ppm in the CP/MAS 29 Si NMR spectrum correspond to Q sites and have an integrated area on the CP/MAS 29 Si NMR spectrum, and wherein the surface-treated metal oxide particles have (1) a ratio D:T of the integrated area of the resonance signals with chemical shifts in the range from −4 ppm to −33 ppm to the integrated area of the resonance signals with chemical shifts in the range from −33 ppm to −76 ppm between 0.10 to 2.50, and (2) a ratio Q:T of the integrated area of the resonance signals with chemical shifts in the range from −76 ppm to −130 ppm to the integrated area of the resonance signals with chemical shifts in the range from −33 ppm to −76 ppm between 0.10 to 2.50 in the CP/MAS 29 Si NMR spectrum, with the proviso that, when the ratio D:T is 1.16 to 1.29, then the ratio Q:T is not 0.53 to 0.67.