Mesoporous silica particles and production process thereof

Abstract

A process for wet pulverizing mesoporous silica particles while a surfactant exists in mesopores, and mesoporous silica particles having an average particle diameter of 1 μm or less, wherein the volume of mesopores having a diameter of 2 to 50 nm is 0.7 mL/g or more and the geometric standard deviation of a mesopore distribution is 2.0 or less. In the above process, mesoporous silica particles having a particle diameter in a submicron order can be obtained at a high yield without causing the marked collapse of mesopores and can be produced efficiently by using an ordinary pulverizer and safely by using an aqueous medium. The mesoporous silica particles having an average particle diameter of 1 μm or less are useful as an ink absorbent for ink jet recording paper, low-dielectric film, catalyst support, separating agent, adsorbent and medical carrier for medicines.

1 . A process for producing fine mesoporous silica particles, comprising wet pulverizing mesoporous silica particles while a surfactant exists in mesopores.  
     
     
         2 . The process according to  claim 1 , wherein the amount of the surfactant is 20 to 300 parts by weight based on 100 parts by weight of the mesoporous silica particles.  
     
     
         3 . The process according to  claim 1  or  2 , wherein the pH of a solution processed by wet pulverizing is within a range of pH at which mesoporous silica particles are formed from silica source±2.  
     
     
         4 . The process according to  claim 1 , wherein wet pulverizing is carried out to ensure that the fine mesoporous silica particles have an average particle diameter of 1 μm or less.  
     
     
         5 . A process for producing fine mesoporous silica particles, comprising the steps of: 
 a reaction step for forming mesoporous silica particles in a polar solvent by precipitating silica in the presence of a surfactant;    a pulverizing step for wet pulverizing the mesoporous silica particles contained in a reaction mixture obtained in the above reaction step as a solution to be processed; and    a removing step for removing at least part of the surfactant existent in the mesopores of the mesoporous silica particles.    
     
     
         6 . Mesoporous silica particles having an average particle diameter of 1 μm or less, wherein the volume of mesopores having a diameter of 2 to 50 nm is 0.7 mL/g or more and the geometric standard deviation of a mesopore distribution is 2.0 or less.  
     
     
         7 . The mesoporous silica particles according to  claim 6 , wherein the geometric standard deviation of a particle size distribution is 1 to 3.  
     
     
         8 . The mesoporous silica particles according to  claim 6  or  7 , wherein the average diameter of mesopores is 5 nm or more.  
     
     
         9 . The mesoporous silica particles according  claim 1  which have an X-ray diffraction peak corresponding to a d value of 2 to 50 nm.  
     
     
         10 . The mesoporous silica particles according to  claim 6  which are produced by wet pulverizing while a surfactant exists in mesopores.  
     
     
         11 . A mesoporous silica particle dispersion containing the mesoporous silica particles of  claim 6 .  
     
     
         12 . A mesoporous silica granulated product prepared by granulating the mesoporous silica particles of  claim 6 .  
     
     
         13 . Use of the mesoporous silica particles of  claim 6  as an ink absorbent for ink jet recording paper.