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Title:
SILICA SOL HAVING LONG AND THIN PARTICLE FORM AND PRODUCTION THEREOF
Document Type and Number:
Japanese Patent JPH01317115
Kind Code:
A
Abstract:

PURPOSE: To obtain the subject sol exhibiting excellent film-forming property when dried on a solid surface by adding an aqueous solution containing a water-soluble Ca salt or Mg salt to an colloidal aqueous solution of active silicic acid, adding a specific alkali metal compound to the solution and heating the mixture.

CONSTITUTION: An aqueous solution containing a water-soluble Ca salt and/or Mg salt is added to a colloidal aqueous solution of active silicic acid of pH2-4 having an SiO2 content of 1-6wt.%. The weight ratio of the Ca or Mg compound to SiO2 is 1,500-3,500ppm in terms of CaO or MgO. The obtained aqueous solution is mixed with an alkali metal hydroxide, a water-soluble organic base or their water-soluble silicate at a molar ratio (SiO2/M2O) of 20-200 and heated at 60-150°C for 0.5-40hr to obtain a stable alkaline aqueous silica sol having an SiO2 concentration of 1-6wt.% and composed of amorphous colloidal silica particles having thin and long shape with particle diameter ratio (D1/D2) of ≥5 (D1 mμ is particle diameter measured by dynamic light-scattering and D2 mμ is particle diameter measured by N2 gas adsorption), D1 of 40-300mμ and uniform thickness falling within 5-20mμ by electron microscopy and extending along only one plane.


Inventors:
WATABE YOSHITANE
ANDO MIKIO
TANIMOTO KENJI
KAGAMIYA TSUTOMU
KAWASHIMA MAKOTO
Application Number:
JP5227089A
Publication Date:
December 21, 1989
Filing Date:
March 04, 1989
Export Citation:
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Assignee:
NISSAN CHEMICAL IND LTD
International Classes:
C01B33/148; (IPC1-7): C01B33/148