Method for Producing Silica with homogenous silylating agent coating

摘要

Production of silylated silica comprises reacting silica with an organosiloxane having 1-100 or 750-10000 di-, tri- and/or quatro-functional units and up to an equal number of mono-functional units and optionally groups with 1 or 2 hydroxy, alkoxy, halogen or acetoxy groups attached to a silicon atom; or 10-100 or 750-10000 di-, tri- and/or quatro-functional units. Production of silylated silica comprises reacting silica with an organosiloxane with A mono-functional units of formula (I) and B di-, tri- and/or quatro-functional units of formula (IIa-c), in which the organosiloxane can have 1 or 2 X groups attached to silicon (Si) atoms and can contain a number C of SiX or SiX2 groups; R<1>3SiO1/2) (I); (R<1>2SiO2/2) (IIa); (R<1>SiO3/2) (IIb); (SiO4/2) (IIc); B = 1-100 or over 750 and under 10000; B =≥A + C; if A + C = 0, B = 10-100 or over 750 and under 10000; X = OZ, halogen or acetoxy; Z = monovalent 1-4 C alkyl or H; R<1> = optionally mono- or poly-unsaturated, monovalent 1-18 C (halo)hydrocarbyl. An Independent claim is also included for silica with a homogeneous layer of silylating agent on the surface, which has hydrophobic properties and an average primary particle size less than 100 nm, in which the primary particles do not exist in isolated form but as constituents of larger aggregates with a diameter of 100-1000 nm and agglomerates with sizes of 1-500 mu m depending on the external shear load (both as defined in DIN 53206); a specific surface area of 10-300 m<2>/g (measured by BET method to DIN 66131 and DIN 66132), a fractal dimension of the mass Dm≤2.8 and a carbon content NOTLESS 1.0 wt.%.