Abstract: Aqueous dispersions contain at least two chemically different particle types having a diameter on average of less than 100 ?m. The dispersions are resistant to sedimentation and gelling for long periods of time, and can be used for many purposes, such as the polishing of optical surfaces, and in paints and adhesives.

Abstract: Small amounts of boron or boron compounds are effective in stabilizing dispersions of metal oxides such as silica. Boron may be incorporated into fumed silica during its preparation in a flame, may be coated onto a metal oxide surface, or may be incorporated into the liquid continuous phase.

Abstract: Surface-modified solids bearing groups of the formula I SiR12—R—NH2??(I), are prepared by reacting a solid having OH groups on a surface thereof with a cyclic silazane of the general formula II where R is a divalent optionally substituted hydrocarbon radical optionally containing heteroatom containing groups, and R1 is a hydrogen atom, or a monovalent optionally substituted hydrocarbon or hydrocarbonoxy group optionally containing heteroatom-containing groups. The surface-modified solids are preferably metal oxide particles. Such surface-modified particles are useful in numerous products.

Abstract: Aqueous dispersions contain at least two chemically different particle types having a diameter on average of less than 100 ?m. The dispersions are resistant to sedimentation and gelling for long periods of time, and can be used for many purposes, such as the polishing of optical surfaces, and in paints and adhesives.

Abstract: Silylated silica is prepared by silylating silica with an organosiloxane composed of A units of the formula (I) (R13SiO1/2)??(I) and B units of the formulae (IIa-c) (R12SiO2/2), and/or??(IIa) (R1SiO3/2), and/or??(IIb) (SiO4/2)??(IIc), optionally having 1 or 2 attached groups —X on Si atoms, where X is OR, R being hydrogen or a monovalent alkyl radical having 1-4 carbon atoms, halogen, or acetoxy, R1 is a saturated or unsaturated, monovalent, optionally halogenated C1-18 hydrocarbon radical the groups ?SiX or ?SiX2 optionally present in a number C, wherein A, B, and C satisfy the relationships: 1?B?100 or 750<B<10 000, B?A+C, and, when A+C=0, 10?B?100 or 750<B<10 000. The silylated silica has a particularly homogenous coating of silylating agent.

Abstract: A silylated silica having an SiOH density per nm2 of less than 0.6, based on the BET-method surface area (DIN 66131 and 66132), is prepared by silylating silica in a process where loading, reacting, and purifying are performed in separate steps.

Abstract: A silylated silica having an SiOH density per nm2 of less than 0.6, based on the BET-method surface area (DIN 66131 and 66132), is prepared by silylating silica in a process where loading, reacting, and purifying are performed in separate steps.

Abstract: Surface-modified solids bearing groups of the formula I

Abstract: Silylated silica is prepared by silylating silica with an organosiloxane composed of A units of the formula (I)

Abstract: The invention relates to crosslinkable materials based on organopolysiloxanes. Said materials are characterized in that in addition to organopolysiloxanes they contain at least one low-molecular organosilicon compound with 2 to 17 silicon atoms comprising units of the formula (I) R1aR2b(OR3)cSiO4−(a+b+c)/2, R1, R2, R3, a, b and c having the meaning given in claim 1 provided that low-molecular organosilicon compounds comprising units of the formula (I) where b is 0 have at least one unit of the formula (I) in which a is 0 or 1, and at least one unit of the formula (I) in which a is 3.

Abstract: The invention relates to silicon dioxide which bears partially or fully silylated polysilicic acid chains on its surface, wherein the sum of silanol groups of the silicon dioxide surface (SiOH) and grafted-on silylating agent radicals (SiRa) is greater than the number of silanol groups on the surface of untreated silicon dioxide, where a can be 1, 2 or 3 and R can be identical or different and are each a substituted or unsubstituted hydrocarbon radical.

Abstract: The invention relates to a process for the silylation of very finely divided inorganic oxides, in which the very finely divided inorganic oxides are treated with at least one silylating agent which is relatively nonvolatile in the temperature range of the overall process, with the proviso that the relatively nonvolatile silylating agent is admixed with the very finely divided inorganic oxides as a liquid, in the form of a very finely atomized aerosol. Furthermore, the invention relates to a highly apolar, pyrogenic silica prepared by this process.

Abstract: The invention relates to a process for the silylation of very finely divided inorganic oxides, in which the very finely divided inorganic oxides are treated with at least one silylating agent which is relatively nonvolatile in the temperature range of the overall process, with the proviso that the relatively nonvolatile silylating agent is admixed with the very finely divided inorganic oxides as a liquid, in the form of a very finely atomized aerosol. Furthermore, the invention relates to a highly apolar, pyrogenic silica prepared by this process.

Abstract: The invention relates to a process for preparing highly dispersed metal oxides whose surfaces are modified by an ammonium-functional organopolysiloxane as a charge controlling substance for positive chargeable toners, in which the highly dispersed metal oxides are reacted with an organopolysiloxane which contains silicon-bonded terminal hydroxyl and/or alkoxy groups, diorganosiloxane units, in which the two organic radicals are monovalent hydrocarbon radicals, and siloxane units in which the organic radicals contain a positive charged nitrogen which is bonded to silicon via carbon.