In order to provide pigment particles and coating compositions comprising them that are suitable for demanding industrial protective coatings and coatings in the automobile sector, a proposal is made for pigment particles having a surface coating for use in a stratifying coating composition, where the surface coating of the pigment particles is formed using an organic, amino-functional component, which in particular has two or more amino groups, and a reactive, silane-functional component different from the aforesaid component.

The invention provides an organic solvent dispersion of titanium oxide particles in a content of 10% by weight or more in an organic solvent except methanol and ethanol, wherein the titanium oxide particles are surface-treated with a surface treating agent comprising a silane coupling agent having the general formula (I)
(RO).sub.nSiX.sub.4-n(I)
wherein R is an alkyl group having carbon atoms of 1-4, n is 2 or 3, X is an alkyl, a fluoroalkyl, a vinyl or a (meth)acryloyloxyalkyl group, and 12-hydroxystearic acid, and wherein the titanium oxide particles in the organic solvent have a D50 in a range of 1 to 30 nm, and wherein the organic solvent dispersion has a transmittance of 2% or more at a wavelength of 500 nm and a transmittance of 70% or more at a wavelength of 800 nm, a viscosity of 10 mPa.Math.s or less at a temperature of 25 C. immediately after production while the increase in the viscosity is 40 mPa.Math.s or less seven days after production as compared to that of the dispersion immediately after production.

Aqueous dispersion containing a hydrophilic metal oxide powder comprising a metal oxide and a surface modification of the metal oxide, wherein a) the metal oxide is selected from the group consisting of TiO.sub.2, ZrO.sub.2, SiO.sub.2, Al.sub.2O.sub.3, Fe.sub.2O.sub.3, Fe.sub.3O.sub.4, Sb.sub.2O.sub.3, WO.sub.3, CeO.sub.2 and mixed oxides thereof and b) the surface modification b1) comprises silicon atoms and aluminum atoms and b2) the silicon atoms are at least partly bonded to a hydrocarbon radical via a C atom and b3) the Al/Si molar ratio of the surface modification is 1:2-1:20.

A titanium oxide particle includes a metal having a hydrocarbon group, which is bonded to a surface of the titanium oxide particle through an oxygen atom, and absorbs light having a wavelength of 450 nm and light having a wavelength of 750 nm, wherein an element ratio C/Ti between carbon C and titanium Ti in a surface of the titanium oxide particle is from 0.3 to 1.2, and a reduced amount of C/Ti on the surface of the titanium oxide particle before and after irradiation with an ultraviolet ray having a wavelength of 352 nm and at an irradiation intensity of 1.3 mW/cm.sup.2 for 20 hours is from 0.1 to 0.9.

There is provided a surface-modified-metal-oxide-particle material including surface-modified-metal-oxide-particles obtained by performing surface modification on metal oxide particles with a surface-modifying material, in which the surface-modifying material includes a predetermined silicone compound, an average primary particle diameter of the metal oxide particles is 3 nm to nm, viscosity at 25 C. is 1000 Pa.Math.s or less, and transmittance of light at a wavelength of 400 nm to 800 nm and a thickness of 1 mm is 60% or greater, a composition for sealing optical semiconductor element, and an optical semiconductor device using the same.

The present invention relates to a composition comprising a) a stable aqueous dispersion of inorganic pigment particles hydrophobically modified with covalently bonded polysiloxane or silyl groups; and b) a polymeric anionic dispersant; wherein the hydrophobically modified inorganic pigment particles have an average particle size in the range of from 200 nm to 10 m, and the solids content of the hydrophobically modified inorganic pigment particles is from 10 to 80 weight percent, based on the weight of inorganic pigment particles and water. The composition of the present invention provides a way to improve water resistance in coatings formulations.

The present invention aims to provide a method of producing a fine particulate inorganic oxide dispersion, which makes it possible to easily disperse a fine particulate inorganic oxide while reducing the amount of dispersant used. The present invention relates to a method of producing a fine particulate inorganic oxide dispersion, the method including mixing the following components (A) to (D): (A) at least one fine particulate inorganic oxide selected from the group consisting of zirconium oxide (ZrO.sub.2), titanium oxide (TiO.sub.2), and barium titanate (BaTiO.sub.3), (B) a dispersant, (C) an alkoxysilane compound, and (D) a solvent having the following Hansen solubility parameters: a hydrogen bonding component (dH) of 11 or less and a polar component (dP) of 4 or more; and wet grinding the resulting mixture.

A method for coating the surface of inorganic solid particles in an aqueous suspension, particularly for coating titanium dioxide with SiO.sub.2 includes: a) disagglomeration of the solid particles contained in aqueous suspension, b) addition of a water-soluble precursor of the coating substance to the suspension, c) immediately following step b) homogenization of the suspension, where the temperature and pH value of the suspension do not change significantly in steps a) to c), d) feeding the slurry into a tank and precipitation of the coating substance onto the particle surface and, optionally, application of further coatings, and e) separation of the solid particles from the suspension. The method produces to a highly homogeneous and continuous skin on the particle surface, and to less separately precipitated coating substance.

Surface-modified nanoparticles wherein each nanoparticle includes an inorganic core and surface modifying groups, wherein the surface modifying groups include at least one triorganoborane-amine complex having the structure ZNHR.sup.1B(R.sup.2).sub.3 wherein: Z is a divalent organic group; R.sup.1 is H or an organic group; and each R.sup.2 is independently an organic group bound to the boron atom through a carbon atom. The inorganic core is typically an inorganic oxide core, e.g., silica, zirconia, or alumina.

The invention provides an organic solvent dispersion of titanium oxide particles in a content of 10% by weight or more in an organic solvent except methanol and ethanol,

wherein the titanium oxide particles are surface-treated with a surface treating agent comprising a silane coupling agent having the general formula (I)

(RO).sub.nSiX.sub.4-n (I)

wherein R is an alkyl group having carbon atoms of 1-4, n is 2 or 3, X is an alkyl, a fluoroalkyl, a vinyl or a (meth)acryloyloxyalkyl group, and 12-hydroxystearic acid, and

wherein the titanium oxide particles in the organic solvent have a D50 in a range of 1 to 30 nm, and

wherein the organic solvent dispersion has a transmittance of 2% or more at a wavelength of 500 nm and a transmittance of 70% or more at a wavelength of 800 nm, a viscosity of 10 mPa.Math.s or less at a temperature of 25 C. immediately after production while the increase in the viscosity is 40 mPa.Math.s or less seven days after production as compared to that of the dispersion immediately after production.