Non-porous spherical silica and method for production thereof
AssigneeMitsubishi Rayon Co., Ltd.
InventorsYasuhiro Unehara, Masashi Nishida, Teruo Miyakawa
Life of this patent
Estimating the term…
Abstract
Non-porous spherical silica having a mean particle diameter of 0.1–20 μm and satisfying the following conditions: (a) a maximum particle diameter is 4 times the mean particle diameter or less; (b) η1/η2<1.0, wherein η1 and η2 are the viscosity of a 70:30 (by weight) mixture of the non-porous spherical silica and a Bisphenol A type liquid epoxy resin, as measured at a rotation number of 0.5 rpm and 2.5 rpm, respectively, in a viscometer.
Claims3
A process for producing non-porous spherical silica comprising following steps (1)–(7):
- (1) a step of emulsification comprising:
- preparing a water-in-oil type (W/O type) emulsion in which an aqueous solution of alkali silicate is dispersed in the form of fine particles as a dispersed phase;
- (2) a step of coagulation comprising:
- mixing the water-in-oil type (W/O type) emulsion prepared in step (1) with 15–20% by weight of an aqueous solution of mineral acid and thereby forming spherical silica gel so that the concentration of the mineral acid comes to 10% by weight or more after the reaction;
- (3) a step of extraction comprising:
- heating the reaction mixture containing the spherical silica gel formed in step (2) at a temperature not lower than 50° C. and thereby extracting impurities;
- (4) a step of washing comprising:
- washing the spherical silica gel from which the impurities have been extracted in step (3);
- (5) a step of drying comprising:
- drying the spherical silica gel washed in step (4);
- (6) a step of disintegration comprising carrying out disintegration with a screen at the time of the drying or after the drying of step (5);
- (7) a step of calcinating comprising:
- calcinating the spherical silica gel disintegrated in step (6).
A process for producing non-porous spherical silica comprising the following steps (1)–(6):
- (1) a step of emulsification comprising:
- preparing a water-in-oil type (W/O type) emulsion in which an aqueous solution of alkali silicate is dispersed in the form of fine particles as a dispersed phase, wherein the total content of metals other than alkali metals and silicon in the solution is 0.1% by weight or less;
- (2) a step of coagulation comprising:
- mixing the water-in-oil type (W/O type) emulsion prepared in step (1) with an aqueous solution of mineral acid to form spherical silica gel;
- (3) a step of washing comprising:
- washing the spherical silica gel formed in step (2);
- (4) a step of drying comprising:
- drying the spherical silica gel washed in step (3);
- (5) a step of disintegration comprising:
- carrying out disintegration with a screen at the time of the drying or after the drying of step (4);
- (6) a step of calcinating comprising calcinating the spherical silica gel disintegrated in step (5).
Dependencies are inferred from the claim text.