Aqueous dispersion of hydrophobized silicon dioxide powder comprising a dispersing agent

An aqueous dispersion comprising hydrophobized silicon dioxide powder, wherein the content of hydrophobized silicon dioxide powder is between 5 and 50 wt. % and the dispersion comprises at least one compound of the general formula

• R1—COO—(CH2—CH(Ph)—O)a—(CnH2n-xR2x—O)b—R3 (I)
• wherein
• R1 is hydrogen, a linear or branched, saturated or unsaturated alkyl chain having 1 and up to 29 carbon atoms, a phenyl radical, an alkyl-substituted phenyl radical having up to ten carbon atoms in the alkyl radical,
• R2 is an alkyl radical having 1 to 5 C atoms,
• R3 is hydrogen, an alkyl chain having 1 and up to 18 carbon atoms, a benzyl radical, an alkyl-substituted benzyl radical having up to four carbon atoms in the alkyl radical,
• a C(O)R5 group with a radical R5 which contains an alkyl chain having 1 to 18 carbon atoms,
• a C(O)NHR6 group with a radical R6 which contains a hydrogen atom or an alkyl chain having 1 to 18 carbon atoms,
• —C(O)OR7, which contains an alkyl chain R7 having 1 to 18 carbon atoms,
• Ph is a phenyl derivative with the general formula
• —(C6H5-yR4y)—, wherein R4 is a hydroxyl radical, an alkyl radical having 1 to 6 carbon atoms or an alkoxy radical having 1 to 6 carbon atoms, and y is a number from 0 to 5,
• a is 0 to 5, b is 10 to 150, n is 2 to 4, x is 0 or 1, wherein the compound is present in an amount sufficient to inhibit separation of the dispersion for at least 30 days.