Fine inorganic oxide dispersion, coating composition, optical film, antireflection film, polarizing plate, and image display device

Abstract

An inorganic oxide dispersion containing an organic solvent, and inorganic oxide particles surface-treated with at least one of a hydrolyzate and a partial condensate of an organosilane compound represented by formula (I), the inorganic oxide particles being dispersed in the organic solvent: (R 10 ) m —Si(X) 4−m (I) as defined herein, the surface treatment of the inorganic oxide particles being carried out in a presence of at least one of: (a) an acid catalyst; and (b) a metal chelate compound having Zr, Ti or Al as a center metal and at least one of an alcohol represented by formula: R 3 OH in which R 3 represents an allyl group having 1 to 10 carbon atoms, and a compound represented by formula: R 4 COCH 2 COR 5 as defined herein, as a ligand.

1 . An inorganic oxide dispersion containing an organic solvent, and inorganic oxide particles surface-treated with at least one of a hydrolyzate and a partial condensate of an organosilane compound represented by formula (I), the inorganic oxide particles being dispersed in the organic solvent: 
         (R 10 ) m —Si(X) 4−m   (I) 
       wherein R 10  represents a substituted or unsubstituted alkyl group or a substituted or unsubstituted aryl group; X represents a hydroxyl group or a hydrolyzable group; and m represents an integer of 1 to 3, 
 the surface treatment of the inorganic oxide particles being carried out in a presence of at least one of:  
 (a) an acid catalyst; and  
 (b) a metal chelate compound having Zr, Ti or Al as a center metal and at least one of an alcohol represented by formula: R 3 OH in which R 3  represents an alkyl group having 1 to 10 carbon atoms, and a compound represented by formula: R 4 COCH 2 COR 5  in which R 4  represents an alkyl group having 1 to 10 carbon atoms; and R 5  represents an alkyl group having 1 to 10 carbon atoms or an alkoxy group having 1 to 10 carbon atoms, as a ligand.  
 
     
     
         2 . A process for producing a dispersion of inorganic oxide particles dispersed in an organic solvent, comprising the steps of: 
 (1) surface treating inorganic oxide particles with at least one of a hydrolyzate and a partial condensate of an organosilane compound represented by formula (I):     (R 10 ) m —Si(X) 4−m   (I)   wherein R 10  represents a substituted or unsubstituted alkyl group or a substituted or unsubstituted aryl group; X represents a hydroxyl group or a hydrolyzable group; and m represents an integer of 1 to 3, in an organic solvent having a small ketone solvent content in a presence of at least one of (a) an acid catalyst and (b) a metal chelate compound having Zr, Ti or Al as a center metal and at least one of an alcohol represented by formula: R 3 OH in which R 3  represents an alkyl group having 1 to 10 carbon atoms, and a compound represented by formula: R 4 COCH 2 COR 5  in which R 4  represents an alkyl group having 1 to 10 carbon atoms; and R 5  represents an alkyl group having 1 to 10 carbon atoms or an alkoxy group having 1 to 10 carbon atoms, as a ligand, and    (2) replacing the organic solvent used for the surface treatment with an organic solvent having an increased ketone solvent content.    
     
     
         3 . An inorganic oxide dispersion obtained by the process according to  claim 2 .  
     
     
         4 . The inorganic oxide dispersion according to  claim 1 , wherein the inorganic oxide particles are surface treated with the at least one of a hydrolyzate and a partial condensate of the organosilane compound represented by formula (I) and a compound having at least one of a fluoroalkyl group and a fluorine-containing aromatic group.  
     
     
         5 . The inorganic oxide dispersion according to  claim 4 , wherein at least one of the organosilane compound represented by formula (1) and the compound having at least one of a fluoroalkyl group and a fluorine-containing aromatic group is a fluorine-containing silane coupling agent represented by formula (1): 
         (Rf—L 1 ) n —Si(R 11 ) n−4   (1) 
       wherein Rf represents a straight-chain, branched or cyclic fluoroalkyl group having 1 to 20 carbon atoms or a fluorine-containing aromatic group having 6 to 14 carbon atoms; L 1  represents a divalent linking group having 10 or fewer carbon atoms; R 11  represents a hydroxyl group or a hydrolyzable group; and n represents an integer of 1 to 3.  
     
     
         6 . The inorganic oxide dispersion according to  claim 5 , wherein the fluorine-containing silane coupling agent is represented by formula (2): 
         C n F 2n+1 —(CH 2 ) m —Si(R) 3   (2) 
       wherein n represents an integer of 1 to 10; m represents an integer 1 to 5; and R represents an alkoxy group having 1 to 5 carbon atoms or a halogen atom.  
     
     
         7 . The inorganic oxide dispersion according to  claim 1 , wherein the organosilane compound of formula (I) is represented by formula (II):  
       
         
           
           
               
               
           
         
       
       wherein R 10  represents a substituted or unsubstituted alkyl group or a substituted or unsubstituted aryl group, X represents a hydroxyl group or a hydrolyzable group; R 1  represents a hydrogen atom, a methyl group, a methoxy group, an alkoxycarbonyl group, a cyano group, a fluorine atom or a chlorine atom; Y represents a single bond, —COO—, —CONH— or —O—; L represents a divalent linking group; and n represents 0 or 1.  
     
     
         8 . The inorganic oxide dispersion according to  claim 1 , wherein the inorganic oxide particles are silica particles.  
     
     
         9 . The inorganic oxide dispersion according to  claim 1 , wherein the inorganic oxide particles are hollow silica particles.  
     
     
         10 . A coating composition comprising the inorganic oxide dispersion according to  claim 1  and a film-forming composition comprising a compound having an ethylenically unsaturated group.  
     
     
         11 . The coating composition according to  claim 10 , wherein the compound having an ethylenically unsaturated group is a main component of the film forming composition.  
     
     
         12 . An optical film comprising a transparent substrate and a layer formed of the coating composition according to  claim 10 .  
     
     
         13 . The optical film according to  claim 12 , wherein the inorganic oxide particles in the coating composition are hollow particles, and the layer has a refractive index of 1.20 to 1.46.  
     
     
         14 . The optical film according to  claim 12 , wherein the inorganic oxide particles in the coating composition are hollow silica particles having a refractive index of 1.17 to 1.40.  
     
     
         15 . An antireflection film comprising a transparent substrate and an antireflection layer provided on the substrate, the antireflection layer comprising a low refractive layer formed of the coating composition according to  claim 10 .  
     
     
         16 . The antireflection film according to  claim 15 , wherein the inorganic oxide particles of the coating composition are hollow silica particles an average particle size of which is 30% to 150% of a thickness of the low refractive layer.  
     
     
         17 . The antireflection film according to  claim 15 , wherein the coating composition of the low refractive layer contains a fluoropolymer represented by formula (A):  
       
         
           
           
               
               
           
         
       
       wherein L represents a linking group having 1 to 10 carbon atoms; m represents 0 or 1; X represents a hydrogen atom or a methyl group; A represents a repeating unit derived from at least one vinyl monomer; and x, y, and z represent a mole percent of respective repeating units in ranges 30≦x≦60, 5≦y≦70, and 0≦z≦65.  
     
     
         18 . A polarizing plate having a polarizing film protected with the antireflection film according to  claim 15 .  
     
     
         19 . An image display device having the antireflection film according to  claim 15  disposed as an outermost surface thereof.  
     
     
         20 . An image display device having the polarizing plate according to  claim 18  disposed as an outermost surface thereof.