Abstract: An optical resin material, which, while able to form a plastic optical element produceable at low cost, has excellent heat resistance and, at the same time, has excellent optical stability high enough to avoid a change in optical properties even after use for a long period of time, and an optical element using the optical resin material. The optical resin material contains a curable resin and hydrophobic oxide particles and is characterized in that it satisfies an absorbance intensity ratio B/A of not less than 0.01 and not more than 0.25, wherein A represents an absorbance intensity at 1720 cm?1 in an infrared absorption spectrum of the optical resin material after curing; and B represents an absorbance intensity at 1637 cm?1, and the volume average particle diameter of the hydrophobic oxide particles is not less than 1.0 nm and not more than 50 nm.

Abstract: Provided are an optical organic-inorganic composite material exhibiting excellent transparency with respect to light having a short wavelength of around 405 nm and an optical element fitted with the optical organic-inorganic composite material, and sufficiently improving temperature dependence of the optical property (refractive index) by utilizing a resin with which an optical element is prepared at low coat in comparison to a glass material. Disclosed is an optical organic-inorganic composite material comprising inorganic particles possessing a composite oxide in which at least two kinds of metal oxides are incorporated, the inorganic particles dispersed in a resin in a state of primary particles or in a state where the plural number of primary particles are coagulated, wherein the dispersed particles have a refractive index variation standard deviation ? of 0.03 or less, and the inorganic particles have an average primary particle diameter of 1-50 nm.

Abstract: Disclosed are an organic-inorganic composite material which is small in rate of variation of refractive index with respect to temperature and is excellent in transparency, and an optical element. The organic-inorganic composite material comprises a resin and inorganic microparticles dispersed therein, characterized in that the inorganic microparticles are dispersed in the resin to form dispersion particles in the form of primary particles or in the form in which several primary particles are aggregated, and when particle diameter of the dispersion particles is expressed by D and center-to-center distance between the centers of any of the dispersion particles and a dispersion particle adjacent thereto is expressed by L, the particle diameter D and the center-to-center distance L satisfy the conditions defined by the following formulas (1) and (2).

Abstract: A thermoplastic resin composition comprising a thermoplastic resin and inorganic particles dispersed in the thermoplastic resin, the thermoplastic resin being melt-moldable, wherein nd and vd of the thermoplastic resin composition satisfy Formula (1), provided that nd represents a refractive index measured at a wavelength of 588 nm and vd represents an Abbe's number: nd>1.82?0.

Abstract: An ink-jet recording sheet comprising a support having thereon an ink receptive layer containing silica microparticles and a water-soluble resin, wherein the ink receptive layer is a porous layer having ink receptive voids with a peak value in a distribution curve of radii of the ink receptive voids of 10 to 50 nm; and the silica microparticles are prepared by pulverizing a silica powder, two parameters X and Y of the silica microparticles satisfying the following relationship: 150<Y+17×loge(X)<500, X being a number of silica microparticles having a diameter of not less than 10 ?m contained per gram of the silica microparticles; and Y being an average particle diameter of the silica microparticles measured in nm.

Abstract: A method for producing an ink-jet recording medium, comprising the steps of: (a) shear processing a dispersion of pigment particles at a shear rate of 103 to 105 s?1; (b) mixing the dispersion of pigment particles with a water-soluble polymer to obtain a coating composition; and (c) applying the coating composition onto a surface of a support.

Abstract: An ink-jet recording medium is disclosed. The ink accepting layer of the recording medium contains silica dispersion containing silica particles having a ratio of a free silanol group of 1.0 to 4.5. Silica particles and silica particle dispersion are also disclosed.

Abstract: An ink-jet recording sheet comprising a support having thereon an ink receptive layer containing silica microparticles and a water-soluble resin, wherein the ink receptive layer is a porous layer having ink receptive voids with a peak value in a distribution curve of radii of the ink receptive voids of 10 to 50 nm; and the silica microparticles are prepared by pulverizing a silica powder, two parameters X and Y of the silica microparticles satisfying the following relationship: 150<Y+17×loge (X)<500, X being a number of silica microparticles having a diameter of not less than 10 &mgr;m contained per gram of the silica microparticles; and Y being an average particle diameter of the silica microparticles measured in nm.

Abstract: An ink-jet recording medium is disclosed. The ink accepting layer of the recording medium contains silica dispersion containing silica particles having a ratio of a free silanol group of 1.0 to 4.5. Silica particles and silica particle dispersion are also disclosed.

Abstract: A method for producing an ink-jet recording medium, comprising the steps of: (a) shear processing a dispersion of pigment particles at a shear rate of 103 to 105 s−1; (b) mixing the dispersion of pigment particles with a water-soluble polymer to obtain a coating composition; and (c) applying the coating composition onto a surface of a support.