Metal oxide powder and method for manufacture thereof
AssigneeTokuyama Corporation
InventorsWakana Tomimatsu, Tadahiro Fukuju, Hiroshi Numa
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Abstract
The present invention provides a globular-shaped metal oxide powder with excellent thermal insulation performance and reduced bulk density, and a method of manufacture thereof, wherein the metal oxide powder has globular independent particles as the main component, and has BET specific surface area of 400 to 1000 m2/g, BJH pore volume of 2 to 8 mL/g, and oil absorption of no less than 250 mL/100g. The present invention also provides a method for manufacturing the hollow and globular shaped metal oxide powder including the step of forming an O/W/O emulsion.
Claims8
A metal oxide powder comprising globular independent particles as main component,
- said metal oxide powder having:
- BET specific surface area of 400 to 1000 m2/g;
- BJH pore volume of 2 to 8 mL/g;
- and
- oil absorption measured by refined linseed oil method specified in JIS K5101-13-1 of no less than 250 mL/100 g,
- wherein each said independent particle includes therein one or more hollow space having a size of 0.5 to 15 μm;
- and
- wherein the metal oxide powder has been hydrophobized by one or more silylating agent represented by the following general formulae (6) to (8)
- RnSiX(4-n) (6)
- wherein in the general formula (6), n represents an integer of 1 to 3;
- R represents methyl group;
- and X represents a leaving group which can leave the molecule by cleavage of bond thereof with the Si atom in a reaction with a compound having a hydroxyl group,
- wherein in the general formula (7), R1 represents an alkylene group;
- R2 and R3 each represent methyl group;
- and R4 and R5 independently represent a hydrogen atom or a hydrocarbyl group,
- wherein in the general formula (8), R6 and R7 each represent methyl group;
- and m represents an integer of 3 to 6.
A method for manufacturing a hollow and globular shaped metal oxide powder comprising the successive steps of:
- (i) preparing an aqueous metal oxide sol;
- (ii) forming an O/W/O emulsion wherein the aqueous metal oxide sol composes the W phase of the O/W/O emulsion;
- (iii) causing gelation of the aqueous metal oxide sol, thereby converting the O/W/O emulsion into a dispersion of a gel;
- (iv) replacing water in the dispersion with a solvent which has a surface tension at 20° C. of no more than 30 mN/m;
- (v) treating the gel with a hydrophobing agent;
- and
- (vi) removing the solvent used in the replacing step (iv),
- wherein the hydrophobing agent is one or more silylating agent represented by the following general formulae (6) to (8)
- RnSiX(4-n) (6)
- wherein in the formula (6), n represents an integer of 1 to 3;
- R represents methyl group;
- and X represents a leaving group which can leave the molecule by cleavage of bond thereof with the Si atom in a reaction with a compound having a hydroxyl group,
- wherein in the formula (7), R1 represents an alkylene group;
- R2 and R3 each represent methyl group;
- and R4 and R5 independently represent a hydrogen atom or a hydrocarbyl group,
- wherein in the formula (8), R6 and R7 each represent methyl group;
- and m represents an integer of 3 to 6.
Dependencies are inferred from the claim text.