METHOD FOR PRODUCING MESOPOROUS SILICA PARTICLES

• US 20120256336A1
• Filed: 12/14/2010
• Published: 10/11/2012
• Est. Priority Date: 12/18/2009
• Status: Active Grant

• Current Assignee: KAO Corporation
• Original Assignee: KAO Corporation
• Inventors: Yano, Toshihiro, Hosokawa, Hiroji, Komatsu, Masaki, Yoshida, Jun
• Granted Patent: US 8,889,044 B2
• Time in Patent Office: Days
• US Class Current: 264/4.6
• CPC Class Codes: B82Y 30/00 Nanotechnology for materials or surface science, e.g. nanocomposites
• CPC Class Codes: C01B 33/18 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 Class Codes: C01B 37/02 Crystalline silica-polymorphs, e.g. silicalites dealuminated aluminosilicate zeolites
• CPC Class Codes: C01P 2002/70 defined by measured X-ray, neutron or electron diffraction data
• CPC Class Codes: C01P 2002/72 by d-values or two theta-values, e.g. as X-ray diagram
• CPC Class Codes: C01P 2004/34 hollow
• CPC Class Codes: C01P 2004/62 Submicrometer sized, i.e. from 0.1-1 micrometer
• CPC Class Codes: C01P 2004/64 Nanometer sized, i.e. from 1-100 nanometer
• CPC Class Codes: C01P 2004/84 one phase coated with the other
• CPC Class Codes: C01P 2006/12 Surface area
• CPC Class Codes: C01P 2006/16 Pore diameter
• CPC Class Codes: C08K 3/36 Silica
• CPC Class Codes: C08K 7/26 Silicon- containing compounds
• CPC Class Codes: C09C 1/3063 Treatment with low-molecular organic compounds
• CPC Class Codes: C09D 7/42 Gloss-reducing agents
• CPC Class Codes: C09D 7/61 inorganic
• CPC Class Codes: C09D 7/67 Particle size smaller than 100 nm
• CPC Class Codes: C09D 7/68 Particle size between 100-1000 nm
• CPC Class Codes: C23C 18/1212 Zeolites, glasses
• CPC Class Codes: C23C 18/122 Inorganic polymers, e.g. silanes, polysilazanes, polysiloxanes
• CPC Class Codes: C23C 18/1245 : Inorganic substrates other than metallic
• CPC Class Codes: C23C 18/1254 : Sol or sol-gel processing
• CPC Class Codes: C23C 18/127 : Preformed particles
• CPC Class Codes: Y10S 977/773 : Nanoparticle, i.e. structure having three dimensions of 100 nm or less
• CPC Class Codes: Y10S 977/89 : Deposition of materials, e.g. coating, cvd, or ald

Abstract

The present invention relates to a method for producing mesoporous silica particles including a silica-containing outer shell portion with a mesoporous structure. The method includes the steps of: (I) pressurizing a mixed solution containing a hydrophobic organic compound, a surfactant, and an aqueous solvent by a high-pressure emulsification method so as to form an emulsion that includes emulsion droplets containing the hydrophobic organic compound; (II) adding a silica source to the emulsion so as to form a silica-containing outer shell portion with a mesoporous structure on a surface of the emulsion droplets, and precipitating composite silica particles including the outer shell portion and the emulsion droplets on an inner side relative to the outer shell portion; and (III) removing the emulsion droplets from the composite silica particles.

According to the production method of the present invention, it is possible to produce easily mesoporous silica particles that have a small average particle size and include fewer coarse particles. Thus, the mesoporous silica particles produced by this method are useful in fields that handle a paint composition for an antireflection film and a coating film.

Claims

1. :

A method for producing mesoporous silica particles, the method comprising;

pressurizing a mixed solution comprising a hydrophobic organic compound, a surfactant, and an aqueous solvent by a high-pressure emulsification method so as to form an emulsion that comprises emulsion droplets comprising the hydrophobic organic compound;

adding a silica source to the emulsion so as to form a silica-containing outer shell portion with a mesoporous structure on a surface of the emulsion droplets, and precipitating composite silica particles comprising the outer shell portion and the emulsion droplets on an inner side relative to the outer shell portion; and

removing the emulsion droplets from the composite silica particles to obtain mesoporous silica particles having a silica-containing out shell portion having a mesoporous structure.

2. :

The method for producing mesoporous silica particles according to claim 1, wherein the mesoporous silica particles have an average pore size of 1 to 3 nm and an average primary particle size of 0.005 to 0.2 μ

m.

3. :

The method for producing mesoporous silica particles according to claim 1, wherein the surfactant is at least one quaternary ammonium salt represented by general formulae (1) or (2)

[R¹(CH₃)₃N]⁺X⁻

 

 

(1)

[R¹R²(CH₃)₂N]⁺X⁻

 

 

(2)

where R¹ and R² each independently represent a linear or branched alkyl group having a carbon number of 4 to 22, and X⁻

represents a monovalent anion.

4. :

The method for producing mesoporous silica particles according to claim 1, wherein the silica source yields a silanol compound by hydrolysis.

5. :

The method for producing mesoporous silica particles according to claim 1, wherein said removing comprises baking the composite silica particles so as to remove the emulsion droplets and the surfactant from the composite silica particles, thereby obtaining hollow mesoporous silica particles with gas filled in a hollow portion present on an inner side relative to the outer shell portion.

6. :

The method for producing mesoporous silica particles according to claim 5, wherein the hollow portion of the hollow mesoporous silica particles has an average diameter of 0.004 to 0.15 μ

m.

7. :

The method for producing mesoporous silica particles according to claim 5, wherein a powder X-ray diffraction spectrum of the hollow mesoporous silica particles obtained by irradiation with a CuKα

1 ray (λ

=0.154050 nm) exhibits are at least one peak having a peak top in a region of a diffraction angle (2θ

) corresponding to a crystal lattice spacing (d) in a range of 2 to 6 nm.

8. :

The method for producing mesoporous silica particles according to claim 5, wherein the hollow mesoporous silica particles have a BET specific surface area of 500 to 1500 m²/g.

9. :

The method for producing mesoporous silica particles according to claim 1, wherein said removing comprises contacting a cation exchange resin with a dispersion solution comprising the composite silica particles obtained from said adding so as to remove the surfactant from the composite silica particles, and then diluting the dispersion solution with an organic solvent and concentrating the same in this order so as to remove the emulsion droplets from the composite silica particles, whereby mesoporous silica particles with the organic solvent filled in a hollow portion present on an inner side relative to the outer shell portion are obtained.

10. :

A paint composition comprising;

a matrix forming material; and

mesoporous silica particles having an average primary particle size of 10 to 200 nm that are produced by the method for producing mesoporous silica particles according to claim 1.

11. :

The paint composition according to claim 10, wherein the mesoporous silica particles have an average pore size of 1.0 to 2.5 nm in the outer shell portion.

12. :

A coating film formed using the paint composition according to claim 10.

13. :

The coating film according to claim 12, comprising;

a matrix; and

hollow mesoporous silica particles that have a silica-containing outer shell portion with a mesoporous structure and a hollow portion present on an inner side relative to the outer shell portion and have an average primary particle size of 10 to 200 nm.

14. :

The coating film according to claim 12, having a film thickness of 10 to 300 nm.

15. :

An antireflection film comprising the coating film according to claim 12.