Method of producing silica-based particles

Patent metadata

Field	Value
Publication number	US-10040943-B2
Application number	US-63135704-A
Country	US
Kind code	B2
Filing date	Jul 8, 2004
Priority date	Jul 8, 2004
Publication date	Aug 7, 2018
Grant date	Aug 7, 2018

Abstract

Hollow silica-based particles having cavities inside the outer shell having a low refractive index. The method of producing the silica-based particles comprises the following steps (a) and (b):
(a) a step in which, when an aqueous silicate solution and/or an acidic silicic acid solution and an aqueous solution of an alkali-soluble inorganic compound are simultaneously added in an alkali aqueous solution to prepare a dispersion liquid of composite oxide particles, an electrolytic salt is added at the molar ratio of a mole number of the electrolytic salt (M E ) versus that of SiO 2 (M S ) [(M E )/(M S )] in the range from 0.1 to 10, and (b) a step of furthermore adding an electrolytic salt, if necessary, to the dispersion liquid of composite oxide particles and then removing at least a portion of elements constituting the composite oxide other than silicon by adding an acid to prepare a dispersion liquid of silica-based particles.

First claim

What is claimed is:

1. A method of producing silica-based particles comprising:
a step (a-1) of simultaneously adding an aqueous solution of an alkali-soluble inorganic compound and at least one of an aqueous silicate solution and an acidic silicic acid solution to an alkali aqueous solution or an alkali aqueous solution with seed particles dispersed therein, thereby making a dispersion liquid containing composite oxide particles with a molar ratio of MO x /SiO 2 in a range from 0.3 to 1.0,
wherein the MO x denotes an inorganic oxide other than silica, and
the MO x denotes a compound selected from the group consisting of Al 2 O 3 , B 2 O 3 , TiO 2 , ZrO 2 , SnO 2 , Ce 2 O 3 , P 2 O 5 , Sb 2 O 3 , MoO 3 , ZnO 2 , WO 3 , TiO 2 —Al 2 O 3 and TiO 2 —ZrO 2 ;
a step (a-2) of building up the composite oxide particles so that an average particle diameter is in a range from 5 to 300 nm;
a step (a-3) of adding an electrolytic salt to the dispersion liquid obtained by the step (a-2) so that a molar ratio of M E /SiO 2 is in a range of 0.1 to 10, and forming a protective film on each surface of the composite oxide particles so that a molar ratio of MO x /SiO 2 of the protective film is lower than the molar ratio MO x /SiO 2 of the composite oxide particles obtained by the step (a-1),
wherein the electrolytic salt is selected from the group consisting of sodium chloride, potassium chloride, sodium nitrate, potassium nitrate, sodium sulfate, potassium sulfate, ammonium nitrate, ammonium sulfate, magnesium chloride, and magnesium nitrate, and
the M E denotes a mole number of the electrolytic salt; and
a step (b) of adding an acid to the dispersion liquid obtained by the step (a-3) so that element M of the MO x is removed from the composite oxide particles, thereby making a dispersion liquid of silica-based particles with internal cavities therein from the composite oxide particles in the dispersion liquid.

2. The method of producing silica-based particles according to claim 1 further comprising:
a step (d) of cleaning the silica-based particles dispersion liquid obtained by the step (b) and aging the dispersion liquid at a temperature in a range from a room temperature to 300° C.

3. The method of producing silica-based particles according to claim 2 , further comprising:
a step (c) of adding an alkali aqueous solution and an organic silicon compound expressed by the following chemical formula (1) and/or a partially hydrolyzed product thereof in the dispersion liquid of silica-based particles obtained by the step (b) to form a silica coating layer on the particles, the step (c) being performed after the step (b):
R n SiX (4-n)   (1)

wherein R denotes any of a not-substituted or substituted hydrocarbon group having 1 to 10 carbon atoms, an acryl group, an epoxy group, a methacryl group, an amino group, a CF 2 group; X denotes an alkoxy group having 1 to 4 carbon atoms, a silanole group, a halogen atom, or a hydrogen atom; and n denote an integer of 0 to 3.

4. The method of producing silica-based particles according to claim 2 further comprising;
a step (e) of cleaning the silica-based particles dispersion liquid obtained by the step (d) and hydrothermally processing the dispersion liquid at a temperature in a range from 50 to 300° C.

5. The method of producing silica-based particles according to claim 4 , wherein the step (e) is repeated several times.

6. The method of producing silica-based particles according to claim 4 , wherein a content of alkali metal oxide in the silica-based particles or the dispersion liquid of silica-based particles in the step (e) is 5 ppm or below as expressed as that of M 2 O (M denoting an alkali metal element) per silica-based particle.

7. The method of producing silica-based particles according to claim 4 , wherein contents of ammonia and/or ammonium ions in the silica-based particles or the dispersion liquid of silica-based particles is 1500 ppm or below as expressed as that of NH 3 per silica-based particle.

8. The method of producing silica-based particles according to claim 1 , wherein pH of the alkali aqueous solution or the alkali aqueous solution with seed particles dispersed therein is 10 or more.

9. The method of producing silica-based particles according to claim 1 , wherein the inorganic oxide other than silica is alumina.

10. The method of producing silica-based particles according to claim 1 , wherein the dispersion liquid of silica-based particles is cleaned, dried, and calcinated.

11. The method of producing silica-based particles according to claim 1 , wherein an average diameter of the silica-based particles is in a range from 5 to 50 nm.

12. The method of producing silica-based particles according to claim 1 , wherein the electrolytic salt is selected from the group consisting of potassium nitrate, sodium sulfate, ammonium nitrate, and ammonium sulfate.

13. The method of producing silica-based particles according to claim 1 , wherein the molar ratio of M E /SiO 2 is in a range of 0.2 to 8.

14. The method of producing silica-based particles according to claim 1 , wherein alkali-soluble inorganic compound is selected from the group consisting of sodium aluminate, sodium tetraborate, zirconyl ammonium carbonate, potassium antimonate, potassium stannate, sodium aluminosilicate, sodium molybdate, cerium ammonium nitrate, and sodium phosphate.

15. A method of producing silica-based particles comprising:
a step (a-1) of simultaneously adding an aqueous solution of an alkali-soluble inorganic compound and at least one of an aqueous silicate solution and an acidic silicic acid solution to an alkali aqueous solution or an alkali aqueous solution with seed particles dispersed therein, thereby making a dispersion liquid containing composite oxide particles with a molar ratio of MO x /SiO 2 in a range from 0.3 to 1.0,
wherein the MO x denotes an inorganic oxide other than silica, and
the MO x denotes a compound selected from the group consisting of Al 2 O 3 , B 2 O 3 , TiO 2 , ZrO 2 , SnO 2 , Ce 2 O 3 , P 2 O 5 , Sb 2 O 3 , MoO 3 , ZnO 2 , WO 3 , TiO 2 —Al 2 O 3 and TiO 2 —ZrO 2 ;
a step (a-2) of building up the composite oxide particles so that an average particle diameter is in a range from 5 to 300 nm;
a step (a-3) of adding an electrolytic salt to the dispersion liquid obtained by the step (a-2) so that a molar ratio of M E /SiO 2 is in a range of 0.1 to 10,
wherein the electrolytic salt is selected from the group consisting of sodium chloride, potassium chloride, sodium nitrate, potassium nitrate, sodium sulfate, potassium sulfate, ammonium nitrate, ammonium sulfate, magnesium chloride, and magnesium nitrate, and
the M E denotes a mole number of the electrolytic salt;
a step (a-4) of further adding an aqueous solution of an alkali-soluble inorganic compound and at least one of an aqueous silicate solution and an acidic silicic acid solution to the dispersion liquid obtained by the step (a-3) to grow composite oxide particles, and forming a protective film on each surface of the composite oxide particles so that a molar ratio of MO X /SiO 2 of the protective film is lower than the molar ratio of MO X /SiO 2 of the composite oxide particles obtained by the step (a-1), and a molar ratio of M E /SiO 2 of the dispersion liquid of the step (a-4) is in a range of 0.1 to 10; and
a step (b) of adding an acid to the dispersion liquid obtained by the step (a-4) so that element M of the MO x is removed from the composite oxide particles, thereby making a dispersion liquid of silica-based particles with internal cavities therein from the composite oxide parti

Assignees

• Muraguchi Ryo
• Kumazawa Mitsuaki
• Hirai Toshiharu
• Hirai Masafumi
• Jgc Catalysts & Chemicals Ltd

Inventors

• Muraguchi Ryo
• Kumazawa Mitsuaki
• Hirai Toshiharu
• Hirai Masafumi

Classifications

• C01B33/146

  After-treatment of sols ({preparation of hydrosols or aqueous dispersions from hydroorganosols, organosols or dispersions in an organic medium C01B33/141}; preparation of hydroorganosols, organosols or dispersions in an organic medium from hydrosols {or aqueous dispersions} C01B33/145) · CPC title

• C01B33/18 Primary

  Preparation of finely divided silica neither in sol nor in gel form; After-treatment thereof (preparation of aerogels by dehydrating gels C01B33/158; treatment to enhance the pigmenting or filling properties C09C) · CPC title

• C09C1/28

  Compounds of silicon {(C09C1/0009, C09C1/0015, C09C1/0078 take precedence)} · CPC title

• C01P2004/62

  Submicrometer sized, i.e. from 0.1-1 micrometer · CPC title

• C08K7/26

  Silicon- containing compounds · CPC title