Spherical organic polymer-silicon compound composite particles, hollow particles and their production methods

Abstract

The present invention is to provide hollow particles with a low degree of agglomeration and having a high roundness, and a process for producing them. Hollow particles comprising a silicon compound, having an average particle size of from 5 to 65 nm and an average roundness of at least 0.90, and having a shell comprising the silicon compound and having a thickness of from 1 to 20 nm. Further, a method for producing hollow particles, which comprises adding sulfuric acid to a liquid containing spherical organic polymer-silicon compound composite particles having a core comprising an organic polymer and a shell comprising a silicon compound in a medium containing at least 95 mass % of water, followed by heating to carbonize the organic polymer thereby to convert it to a carbide, and subjecting the carbide to decomposition using a liquid oxidizing agent other than sulfuric acid.

1 - 18 . (canceled) 
   
   
       19 . Hollow particles comprising a silicon compound, having an average particle size of from 5 to 65 nm and an average roundness of at least 0.90, and having a shell comprising the silicon compound and having a thickness of from 1 to 20 nm. 
   
   
       20 . The hollow particles according to  claim 19 , having their surface treated with a silane coupling agent. 
   
   
       21 . A method for producing hollow particles, which comprises adding sulfuric acid to a liquid containing spherical organic polymer-silicon compound composite particles having a core comprising an organic polymer and a shell comprising a silicon compound in a medium containing at least 95 mass % of water, followed by heating to carbonize the organic polymer thereby to convert it to a carbide, and subjecting the carbide to decomposition using a liquid oxidizing agent other than sulfuric acid. 
   
   
       22 . The method for producing hollow particles according to  claim 21 , wherein to the liquid containing spherical organic polymer-silicon compound composite particles, sulfuric acid is added in an amount of from 10 to 200 mL per 1 g of the spherical organic polymer-silicon compound composite particles contained in the liquid. 
   
   
       23 . The method for producing hollow particles according to  claim 21 , wherein the heating temperature after sulfuric acid is added is from 200° C. to 300° C., and the liquid oxidizing agent is at least one member selected from the group consisting of nitric acid, hydrogen peroxide and a chloric acid. 
   
   
       24 . The method for producing hollow particles according to  claim 22 , wherein the heating temperature after sulfuric acid is added is from 200° C. to 300° C., and the liquid oxidizing agent is at least one member selected from the group consisting of nitric acid, hydrogen peroxide and a chloric acid. 
   
   
       25 . A method for producing hollow particles, which comprises adding at least one liquid oxidizing agent selected from the group consisting of hydrogen peroxide, hypochlorous acid, chlorous acid, chloric acid and perchloric acid, and nitric acid, to a liquid containing spherical organic polymer-silicon compound composite particles having a core comprising an organic polymer and a shell comprising a silicon compound in a medium containing at least 95 mass % of water, followed by heating to a temperature of from 100 to 150° C. to subject the organic polymer to decomposition. 
   
   
       26 . The method for producing hollow particles according to  claim 25 , wherein to the liquid containing spherical organic polymer-silicon compound composite particles, the liquid oxidizing agent is added in an amount of from 30 to 200 mL per 1 g of the spherical organic polymer-silicon compound composite particles contained in the liquid. 
   
   
       27 . A method for producing hollow particles, which comprises treating the hollow particles obtained by the production method as defined in any one of  claims 21  to  26  in hot water or pressurized hot water of from 80 to 200° C. 
   
   
       28 . The method for producing hollow particles according to any one of  claims 21  to  26 , wherein the silicon compound is silica. 
   
   
       29 . The method for producing hollow particles according to any one of  claims 21  to  26 , wherein the organic polymer is a homopolymer of one type or a copolymer of two or more types selected from the group consisting of styrene, a methacrylate and an acrylate. 
   
   
       30 . Spherical organic polymer-silicon compound composite particles, which have a core comprising an organic polymer and a shell comprising a silicon compound, and have an average particle size of from 5 to 65 nm and an average roundness of at least 0.90. 
   
   
       31 . The spherical organic polymer-silicon compound composite particles according to  claim 30 , wherein the organic polymer for the core has an average particle size of from 2 to 50 nm and an average roundness of at least 0.90. 
   
   
       32 . The spherical organic polymer-silicon compound composite particles according to  claim 30  or  31 , wherein the silicon compound for the shell has a thickness of from 1 to 20 nm. 
   
   
       33 . A method for producing spherical organic polymer-silicon compound composite particles, which comprises adding a liquid containing organic polymer particles in a medium containing at least 70 mass % of an alcohol, to an alcohol solution of a silicon alkoxide to provide a silicon compound covering layer on the surface of the particles. 
   
   
       34 . The method for producing spherical organic polymer-silicon compound composite particles according to  claim 33 , wherein after the spherical organic polymer-silicon compound composite particles are prepared, they are left at rest at a temperature of from 10 to 40° C. for from 1 to 7 days. 
   
   
       35 . The method for producing spherical organic polymer-silicon compound composite particles according to  claim 33  or  34 , wherein the organic polymer is a homopolymer of one type or a copolymer of two or more types selected from the group consisting of styrene, a methacrylate and an acrylate. 
   
   
       36 . A slurry containing from 5 to 40 mass % of the hollow particles as defined in  claim 19  or  20 , wherein the total amount of the hollow particles and an organic solvent in the slurry is from 90 to 99.9 mass %, and the rest mainly comprises water. 
   
   
       37 . The slurry according to  claim 36 , wherein the organic solvent is an alcohol which is liquid at 25° C. and/or a ketone which is liquid at 25° C.