| abstract |
The present invention provides a variety of fine particlesnhaving a structure wherein a porous composite oxide particle isncoated with a porous silica-based inorganic oxide layer, and alsonprovides a substrate having a coating film comprising the finenparticles thereon, which has a low refractive index and excellentnin adhesion with a resin or the like, strength, the ability tonreduce reflection and the like. The fine particles comprise porousncomposite oxide comprising silica and an inorganic oxide othernthan silica, wherein said fine particles are coated with a porousnsilica-based inorganic oxide layer having a thickness from 0.5nto 20 nm. The fine particles include preferably an organic groupndirectly bonded to silicon, and S R /S T , the ratio of the molar amountnof silicon having the organic group directly bonded thereto (S R )nvs the molar amount of the total silicon (S T ), is preferably innthe range from 0.001 to 0.9. The substrate with a coating filmnis characterized in that said coating film contains thenabove-mentioned fine particles and a matrix for forming a coatingnfilm. |