Patent ID: 8470212

Claim:
Infrared shielding nanoparticles, comprising nanoparticles of: tungsten oxide expressed by a general formula W y O z , where: W is tungsten, O is oxygen, and y and z satisfy 2.2≦z/y≦2.999; and/or composite tungsten oxide expressed by a general formula M x W y O z , where: M is H, an alkali metal, an alkali earth metal, a rare earth element, or one or more elements selected from the group consisting of Mg, Zr, Cr, Mn, Fe, Ru, Co, Rh, Ir, Ni, Pd, Pt, Cu, Ag, Au, Zn, Cd, Al, Ga, In, Tl, Si, Ge, Sn, Pb, Sb, B, F, P, S, Se, Br, Te, Ti, Nb, V, Mo, Ta, Re, Be, Hf, Os, Bi, and I, W is tungsten, O is oxygen, and x, y, and z satisfy 0.001≦x/y≦1 and 2.2≦z/y≦3; wherein: an average primary particle size of individual nanoparticles is 1 nm or more and 800 nm or less, and a surface of the nanoparticle is coated with: a first coating film comprising an organic metal compound, and a second coating film coating the first coating film, the second coating film comprising: a tetrafunctional silane compound expressed by a general formula Si(OR) 4 , where each R is an identical or a different univalent hydrocarbon group having 1 to 6 carbon atoms or a partial hydrolysis product of the tetrafunctional silane compound, and the organic metal compound; wherein a combined thickness of the first and second coating films coating the surface of the nanoparticle is 5 nm or more and 30 nm or less; and wherein an addition amount of the organic metal compound is 0.05 parts by weight to 300 parts by weight expressed in terms of a metal element, based on 100 parts by weight of the tungsten oxide nanoparticles and/or the composite tungsten oxide nanoparticles.