Hydrophobic surface modification dry silica powder

摘要

PPROBLEM TO BE SOLVED: To provide a hydrophobized dry process silica powder or the like enhancing fluidity and cleaning properties of a toner and suitable as an external additive of electronic photography. PSOLUTION: This dry process silica powder is surface-treated with an organopolysiloxane for hydrophobization, preferably with an organopolysiloxane expressed by general formula: X-[Si(R)(R)O]SBp/SB-Si(R)(R)-X (wherein at least 80% of the substituent R is a methyl group; part of R may be a hydrogen atom, an alkyl group, halogenated alkyl group, alkenyl group, or an aryl group; X is a hydrogen atom, an alkyl group, vinyl group, a halogen atom, a hydroxy group or alkoxy group; and p is an integer of 15-500), where hydrophobicity thereof is 85% or above, and the ratio (A/D) of a single silanol group integral value (A) and a siloxane integral value (D) respectively measured bySP29/SPSi solid NMR satisfies the inequality of 0.25(A/D)0.50. PCOPYRIGHT: (C)2007,JPO&INPIT