WO2009057821A1

WO2009057821A1 - Microparticle of metal or metal oxide having silicon-containing organic group, and method for producing the same

Info

Publication number: WO2009057821A1
Application number: PCT/JP2008/070252
Authority: WO
Inventors: Takuya Ogawa; Yoshito Oshima
Original assignee: Dow Corning Toray Co., Ltd.; The University Of Tokyo
Priority date: 2007-10-31
Filing date: 2008-10-30
Publication date: 2009-05-07

Abstract

The present invention relates to microparticles of a metal or metal oxide having a silicon-containing organic group with reactivity on the surface thereof, and a method for producing the same. The microparticles of a metal or metal oxide has a silicon-containing organic group represented by general formula (A) fixed on the surface thereof by means of chemical bonding. In the method for producing the microparticles, a silicon-containing compound and an aqueous solution or aqueous dispersion of a metal salt are reacted under the conditions at a temperature of 300°C or greater under pressure of 10 MPa or greater.

Description

DESCRIPTION

Microparticle of Metal or Metal Oxide Having Silicon- Containing Organic Group, and Method for Producing the Same

Technical Field

The present invention relates to microparticles of a metal or metal oxide having a silicon-containing organic group on the surface thereof, and a method for producing the same. Priority is claimed on Japanese Patent Application No. 2007-283859, filed on October 31, 2007, and Japanese Patent Application No. 2007-302000, filed on November 21, 2007, the content of which is incorporated herein by reference.

Background Art

Metal oxide microparticles exhibit superior thermal stability, and are employed alone or in combination with various organic materials in the fields of paints, pigments, cosmetics, catalysts, glass, medicines and the like, by controlling the physical properties such as optical transparency/light-blocking properties, conductive properties/insulation properties and the like. Metal oxide microparticles are usually hydrophilic. For this reason, when they are used in combination with organic materials, the surface of the microparticles is organically modified in order to improve compatibility with the organic materials and improve dispersion properties of the microparticles themselves, in many cases.

A general method in the aforementioned modification methods is one in which metal oxide microparticles and a compound containing an organic group represented by a silane coupling agent are reacted in the presence of an organic solvent and water, and thereby, the organic group is fixed on the surface of the microparticles , as described in Japanese Unexamined Patent Application, First Publication No. 2007-51188 and Japanese Unexamined Patent Application, First Publication No. Hll-322306. In addition, Japanese unexamined Patent Application, First Publication No. H05- 65416 proposes a method in which a polysiloxane is used as the compound containing an organic group. This method is basically the same as the modification method with the silane coupling agent.

On the other hand, as a preparation method with decreased load on the environment utilizing a special reaction site, a method for producing microparticles of a metal oxide in which a supercritical fluid technology is applied is known. In accordance with Japanese Unexamined Patent Application, First Publication No. 2002-210356, it is described that microparticles of a metal oxide are treated with a polymer having silicon or fluorine in supercritical carbon dioxide, and thereby, microparticles coated with the aforementioned polymer are produced. In addition, Japanese Unexamined Patent Application, First Publication No. 2005-194148, and Japanese Unexamined Patent Application, First Publication No. 2006-282503 disclose a technology in which producing microparticles and coating with organic groups are performed at the same time in high-temperature and pressure water. However, in the aforementioned methods, microparticles of a metal oxide having a silicon-containing organic group with reactivity cannot be produced.

Recently, metal microparticles are actively studied as a material for forming wires in the field of electronic materials. In a method for producing metal microparticles , formation of microparticles from a gas phase is general. However, there are problems in that heating devices such as plasma, laser and the like are required, and the aforementioned method is not suitable for bulk production, and thus the production efficiency is reduced. For this reason, various preparation methods in a liquid phase have been proposed. For example, it is believed that nanosized metal microparticles can be produced by a reaction between an aqueous solution of a metal salt and a reducing agent and an auxiliary agent such as an amine (Japanese Unexamined Patent Application, First Publication No. 2007- 84879) or an alcohol (Japanese Unexamined Patent Application, First Publication No. 2007-84930) . However, these methods have a problem in that a product must be isolated from excess reducing agent and auxiliary agent.

On the other hand, in order to overcome the aforementioned problems, a method in which a heat treatment is carried out instead of using the reducing agent has been proposed. For example, a method is disclosed in which a mixture of a metal salt of an organic acid and a higher alcohol (in Japanese Unexamined Patent Application, First Publication No. 2007-46167), an organometal complex (in Japanese Unexamined Patent Application, First Publication No. HlO- 183207), or a metal alkanoate (in Japanese Unexamined Patent Application, First Publication No. 2007-31835) is subjected to a heat treatment under conditions of controlled temperatures. In accordance with the aforementioned methods, metal microparticles exhibiting good dispersibility in organic materials are produced, but the aforementioned methods fail to disclose metal microparticles having a silicon-containing organic group.

As described above, until the present time, no proposals have been made with respect to microparticles of a metal or a metal oxide having a silicon-containing organic group which is believed to be effective in improving compatibility with silicon-based materials such as polysiloxane and the like, as well as with respect to simple and easy methods for producing the same.

Disclosure of Invention

The present invention is carried out under the circumstances of the aforementioned prior art, and has a first objective to provide microparticles of a metal or metal oxide which have a silicon-containing organic group with reactivity on the surface thereof. In addition, the present invention has a second objective to provide a simple and easy method for producing the aforementioned microparticles .

The first objective of the present invention can be achieved by a microparticle of a metal or metal oxide on the surface of which a silicon-containing organic group is fixed by means of chemical bonding wherein the silicon- containing organic group is represented by general formula (A) shown below:

-LpSiR qX(4-p-q) (A)

wherein each R¹ independently represents a substituted or unsubstituted monovalent hydrocarbon group; L represents a divalent linking group of a formula: - (YC_xH_2x) _t (C_xH₂χ-yZ_zO_w) v~ wherein Y is -0-, -S-, or a formula: - NR²- wherein R² is a hydrogen atom or a substituted or unsubstituted monovalent hydrocarbon group, Z is -NH- or - N(CH₃)-, x is an integer ranging from 3 to 20, y is an integer ranging from 0 to 5, z is 0 or 1, w is an integer ranging from 0 to 5, t is an integer ranging from 0 to 50, and v is 0 or 1; p and q are respectively numbers that satisfy the following conditions: 0 < p ≤ 2; 0 < q < 2; and 2 < p + q < 4; and X represents a group of a formula: -(OSiR¹ ₂)_r-K wherein R¹ is the same as described above, K is HO- or a monovalent group of a formula: H (YC_xH_2x) t (CχH_2x-_yZ_zO_w) _v- wherein Y, Z, x, y, z, w, t, and v are the same as described above, and r is a number of 0 or more.

In addition, the second objective of the present invention can be achieved by reacting a silicon-containing compound and an aqueous solution or aqueous dispersion of a metal salt under conditions at a temperature of not less than 300⁰C under pressure of not less than 10 MPa.

The aforementioned silicon-containing compound is preferably a reactive silane represented by general formula (B) shown below:

R³SiR^W (B)

wherein each R¹ independently represents a substituted or unsubstituted monovalent hydrocarbon group;

R³ represents a monovalent organic group having a reactive functional group; W represents a hydrolyzable group or condensation-reactive group selected from the group consisting of a hydrogen atom; a halogen atom; a group of a formula: -OR⁴ wherein R⁴ is a hydrogen atom or a substituted or unsubstituted monovalent hydrocarbon group having 4 or less carbon atoms; a group of a formula: -OC(O)R¹ wherein R¹ is the same as described above; a group of a formula: -O-N=CR¹ ₂ wherein R¹ is the same as described above; a group of a formula: -NR⁵- C(O)R¹ wherein R¹ is the same as described above, and R⁵ is a hydrogen atom or a substituted or unsubstituted monovalent hydrocarbon group; and a group of a formula: - ONH₂, and/or a linear reactive organopolysiloxane represented by general formula (C) shown below:

R⁶R^SiO- (SiR⁶R¹O) s-SiR^R⁶ (C)

wherein each R¹ independently represents a substituted or unsubstituted monovalent hydrocarbon group; each R⁶ independently represents a hydrolyzable group or condensation-reactive group selected from the group consisting of a hydrogen atom; a halogen atom; a group of a formula: -OR⁴ wherein R⁴ is a hydrogen atom or a substituted or unsubstituted monovalent hydrocarbon group having 4 or less carbon atoms; a group of a formula: -OC(O)R¹ wherein R¹ is the same as described above; a group of a formula: -0-N=CR¹2 wherein R¹ is the same as described above; a group of a formula: -NR⁵-C(0)R¹ wherein R¹ is the same as described above, and R⁵ is a hydrogen atom or a substituted or unsubstituted monovalent hydrocarbon group; and a group of a formula: -ONH₂, a substituted or unsubstituted monovalent hydrocarbon group , or a monovalent organic group having a reactive functional group, with the proviso that at least one R⁶ is said hydrolyzable group or condensation-reactive group, or said monovalent organic group; and s is a number of 0 or more.

In addition, the aforementioned reactive functional group in general formulae (B) and (C) is preferably selected from the group consisting of hydroxyl, mercapto, epoxy, amino, amide, ester, carboxyl, and isocyanate groups.

In addition, the aforementioned metal salt is preferably a sulfate, nitrate, acetate, oxalate, hydrochloride, or oxychloride of a metal ranging from group IV to group XV of the periodic table of the elements.

In addition, the blending amount of the silicon-containing compound is preferably not less than 10% by weight with respect to 100% by weight of a metal produced from the metal salt.

Brief Description of Drawings

Fig. 1 is a conceptual view showing one example of a batch- type reaction apparatus by which the preparation method of the present invention is carried out.

Fig. 2 is a conceptual view showing one example of a continuous reaction apparatus by which the preparation method of the present invention is carried out. Fig. 3 is an SEM photograph of microparticles of the present invention obtained in Example 1.

Fig. 4 is a TEM photograph of microparticles of the present invention obtained in Example 1.

Fig. 5 is a photograph showing the result of the EDX analysis of Example 1.

Fig. 6 is an SEM photograph of microparticles of the present invention obtained in Example 2.

Fig. 7 is a TEM photograph of microparticles of the present invention obtained in Example 2.

Fig. 8 is a photograph showing the result of the EDX analysis of Example 2.

Best Modes for Carrying Out the Invention

The microparticles of a metal or metal oxide of the present invention are characterized in that a silicon-containing organic group is fixed on the surface of the microparticles by means of chemical bonding wherein the silicon-containing organic group is represented by general formula (A) shown below:

-LpSiR qX(4-p-q) (A)

wherein each R¹ independently represents a substituted or unsubst ituted monovalent hydrocarbon group; L represents a divalent linking group of a formula: - (YC_xH_2x) t (C_xH₂χ-_yZ_zO_w) _v- wherein Y is -0-, -S-, or a formula: - NR²- wherein R² is a hydrogen atom or a substituted or unsubstituted monovalent hydrocarbon group, Z is -NH- or - N(CH₃)-, x is an integer ranging from 3 to 20, y is an integer ranging from 0 to 5, z is 0 or 1, w is an integer ranging from 0 to 5, t is an integer ranging from 0 to 50, and v is 0 or 1; p and q are respectively numbers that satisfy the following conditions: 0 < p ≤ 2; 0 < q ≤ 2; and 2 < p + q < 4; and X represents a group of a formula: -(OSiR¹ ₂)_r-K wherein R¹ is the same as described above, K is HO- or a monovalent group of a formula: H (YC_xH_2x) _t (C_xH_2x__yZ_zO_w) _v- wherein Y, Z, x, y, z, w, t, and v are the same as described above, and r is a number of 0 or more.

The metals forming the metal microparticles or metal-oxide microparticles of the present invention are not particularly limited, and any metal elements can be used. Typically, as examples thereof, mention may be made of elements of group IV of the periodic table of the elements, and those which are positioned at the right side of the elements of group IV on the periodic table of the elements but at the left and lower side of the line of boron (B) of group XIII - silicon (Si) of group XIV - arsenic (As) of group XV, as well as the elements on that line on the periodic table of the elements. As detailed examples thereof, mention may be made of, for example, Ti, Zr and the like as the elements of group IV; V and the like as the elements of group V; Cr, Mo and the like as the elements of group VI; Mn and the like as the elements of group VII; Fe, Co, Ni, Ru, Rh, Pd, Pt and the like as the elements of group VIII to group X; Cu, Ag, Au and the like as the elements of group XI; Zn and the like as the elements of group XII; Al, Ga, In and the like as the elements of group XIII; Si, Ge, Sn, Pb and the like as the elements of group XIV; and Sb, Bi and the like as the elements of group XV. Among these, Ti, Zr, V, Fe, Ni, Cu, Ag, Au, Zn, Al, Ge and Sn are preferable, and Cu, Ag, Fe and Zn are, in particular, preferable. The aforementioned metal elements may be used alone or as a mixture by combining two or more types thereof. Therefore, as examples of metal oxides, mention may be made of, for example, oxides of Fe, Co, Ni, Cu, Ag, Au, Zn, Al, Ga, In, Si, Ge, Sn, Pb, Ti, Zr, Mn and the like, such as SiO₂, TiO₂, ZnO, SnO₂, Al₂O₃, AlOOH, MnO₂, NiO, Fe₂O₃, Fe₃O₄, Co₃O₄, ZrO₂, BaTiO₃, LiCoO₂, LiMn₂O₄, CuO, Cu₂O, as well as mixtures thereof. Al₂O₃, AlOOH, Cu₂O and CuO are preferable .

The form of metal microparticles or metal-oxide microparticles of the present invention is not particularly- limited, and may be any form such as sphere, spindle, prismatic column, cylinder, plate, needle, or the like. A spherical microparticle is preferable.

The metal microparticles or metal-oxide microparticles of the present invention preferably have an average particle size of 1 μm or less, and in particular, nanoparticles are preferable. Nanoparticles means, in general, particles having an average particle size of 200 nm or less, preferably 150 nm or less, more preferably 100 nm or less, and further preferably 50 nm or less. The microparticles of the present invention may be a mixture of fine particles having various particle sizes, but microparticles having a uniform particle size are preferable. Measurement of the average particle size can be carried out by means of a common measurement method in the art. For example, particle size can be measured by means of a transmission electron microscope (TEM) , field-emission transmission electron microscope (FE-TEM), scanning electron microscope (SEM), field emission scanning electron microscope (FE-SEM) or the like, and an average value therefrom can be obtained.

In the present invention, the silicon-containing organic group is fixed on the surface of micropart icles of a metal or metal oxide by means of chemical bonding. Here, chemical bonding means a strong binding due to covalent bonding, ion bonding or the like, and does not include a bonding due to merely physical adsorption or the like.

In the silicon-containing organic group represented by general formula (A), X can be a reactive site. For this reason, in the case of using this together with a silicon- based material such as polysiloxane, compatibility with the aforementioned silicon-based material is improved, and a reaction with the aforementioned silicon-based material is effectively carried out. In addition, in the microparticles of a metal or metal oxide of the present invention, the silicon atom to which X bonds and the surface of the microparticles of the metal or metal oxide are chemically bonded via at least divalent linking group L. In other words, in the microparticles of the metal or metal oxide of the present invention, the silicon atom to which X bonds never binds to the surface of the microparticles via an oxygen atom. This is different from the case in which the surface of the microparticles of a metal or metal oxide is modified by means of a common silane coupling agent. In the present invention, the silicon atom having the reactive site binds with a degree of freedom for permitting spatially increased movement at the distant position from the surface of the metal or metal oxide. For this reason, a special reactivity can be obtained.

In general formula (A) , the substituted or unsubstituted monovalent hydrocarbon group of R¹ is not particularly limited. Typically, the substituted or unsubstituted monovalent hydrocarbon group is a substituted or unsubstituted monovalent saturated hydrocarbon group having 1 to 20 carbon atoms, preferably having 1 to 10 carbon atoms, and more preferably having 1 to 4 carbon atoms; a monovalent aromatic hydrocarbon group having 6 to 20 carbon atoms and preferably 6 to 12 carbon atoms; or a monovalent unsaturated aliphatic hydrocarbon group having 2 to 20 carbon atoms.

As examples of monovalent saturated hydrocarbon groups having 1 to 20 carbon atoms, mention may be made of, for example, straight or branched alkyl groups such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, pentyl, hexyl, heptyl, octyl, nonyl, and decyl groups; and cycloalkyl groups such as cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl, cyclooctyl groups. A methyl group is preferable.

As examples of monovalent aromatic hydrocarbon groups having 6 to 20 carbon atoms, mention may be made of, for example, phenyl, tolyl, xylyl, and mesityl groups. A phenyl group is preferable. In the specification of the present application, aromatic hydrocarbon groups include groups in which aromatic hydrocarbons and saturated hydrocarbons are combined, in addition to groups consisting of only aromatic hydrocarbons. As examples of groups in which aromatic hydrocarbons and saturated hydrocarbons are combined, mention may be made of, for example, benzyl and phenethyl groups .

As examples of monovalent unsaturated aliphatic hydrocarbon groups having 2 to 20 carbon atoms, mention may be made of, for example, straight or branched alkenyl groups such as vinyl, 1-propenyl, allyl, isopropenyl, 1-butenyl, 2-butenyl, pentenyl, hexenyl groups, as well as cycloalkenyl groups such as cyclopentenyl , and cyclohexenyl groups, and cycloalkenylalkyl groups such as cyclopentenylethyl , and cyclohexenylethyl groups. A vinyl group is preferable.

The hydrogen atom on the aforementioned monovalent hydrocarbon group may be substituted by one or more substituents , and the aforementioned substituents are selected from halogen atoms (fluorine, chlorine, bromine and iodine atoms) .

In addition, L represents a divalent linking group of a formula: -( YC_xH_2x) t (C_xH_2X-_yZ_zO_w) _v- wherein Y is -O-, -S-, or a formula: -NR²- wherein R² is a hydrogen atom or a substituted or unsubstituted monovalent hydrocarbon group, Z is -NH- or -N(CHs)-, x is an integer ranging from 3 to 20, y is an integer ranging from 0 to 5, z is 0 or 1, w is an integer ranging from 0 to 5, t is an integer ranging from 0 to 50, and v is 0 or 1. As examples of monovalent hydrocarbon atoms of R² in the formula, the substituted or unsubstituted monovalent hydrocarbon groups listed in the aforementioned R¹ may be mentioned.

As examples of the aforementioned divalent linking groups, mention may be made of - (OCH₂CH₂) ₃OCH₂CH₂CH₂- wherein a is an integer ranging from 0 to 50, - (OCH (CH₃) CH₂) I₃OCH₂CH₂CH₂- wherein b is an integer ranging from 1 to 50, -SCH₂CH₂CH₂-, -NHCH₂CH₂CH₂-, -N (CH₃) CH₂CH₂CH₂-, -NHCH₂CH₂NHCH₂CH₂CH₂-, - OCH₂CH (OH) CH₂OCH₂CH₂CH₂-, -OCH₂CH (OH) [CH₂I C- wherein c is an integer ranging from 2 to 10,

wherein d is 2 or 3,

wherein d is the same as described above,

wherein d is the same as described above, - OCH₂CH₂CH₂CH (CH₂CH=O) (CH₂) _d- wherein d is the same as described above, and the like.

In addition, p and q are respectively numbers that satisfy the following conditions: 0 < p ≤ 2; 0 < q < 2; and 2 ≤ p + q < 4. In addition, X represents a group of a formula: - (OSiR¹ ₂) _r-K wherein R¹ is the same as described above, K is HO- or a monovalent group of a formula: H (YC_xH_2x) _t (C_xH_2x-yZ_zO_w) _v- wherein Y, Z, x, y, z, w, t, and v are the same as described above, and r is a number of 0 or more.

As examples of the aforementioned X, mention may be made of -OH, -OSi (CHa) ₂CH₂CH₂CH₂OH, -OSi (CH₃)_ZCH₂CH₂CH₂SH, - OSi (CHs) ₂CH₂CH₂CH₂NH₂, -OSi (CHa) ₂CH₂CH₂CH₂N (CH₃) H, - OSi (CH₃) ₂CH₂CH₂CH₂O (CH₂CH₂O) ₂H, - OSi (CH₃) ₂CH₂CH₂CH₂OCH₂CH (OH) CH₂OH, - OSi (CH₃) ₂CH₂CH₂CH₂CH₂CH (OH) CH₂OH,

-OSi (CHs)₂CH₂CH₂CH(CH₂CH=O)CH₂CH₂CH₂OH, and the like.

As examples of silicon-containing organic groups represented by general formula (A) , mention may be made of -OCH₂CH₂CH₂Si (CH₃) ₂0H, -OCH₂CH₂CH₂Si (CH₃) ₂0Si (CH₃) ₂CH₂CH₂CH₂OH, -SCH₂CH₂CH₂Si (CH₃) ₂SH, -SCH₂CH₂CH₂Si (CH₃) ₂0Si (CH₃) ₂CH₂CH₂CH₂SH, -NHCH₂CH₂CH₂Si (CH₃) ₂0H, -

NHCH₂CH₂CH₂Si (CH₃) ₂0Si (CH₃) ₂CH₂CH₂CH₂NH₂ , - (OCH₂CH₂) ₂OCH₂CH₂CH₂Si (CH₃) ₂0H, -

(OCH₂CH₂) ₂OCH₂CH₂CH₂Si (CH₃) ₂0Si (CH₃) ₂CH₂CH₂CH₂O (CH₂CH₂O) ₂H, - OCH₂CH (OH) CH₂OCH₂CH₂CH₂Si (CH₃) ₂0H, -

OCH₂CH (OH) CH₂OCH₂CH₂CH₂Si (CH₃) ₂0Si (CH₃ ) ₂CH₂CH₂CH₂OCH₂CH (OH ) CH₂OH, -OCH₂CH (OH) CH₂CH₂CH₂CH₂Si (CH₃) ₂0H, - OCH₂CH (OH) CH₂CH₂CH₂CH₂Si (CH₃) ₂0Si ( CH₃ ) ₂CH₂CH₂CH₂CH₂CH (OH) CH₂OH,

-OCH₂CH₂CH₂CH (CH₂CH=O) CH₂CH₂Si (CH₃) ₂OH,

OCH₂CH₂CH₂CH (CH₂CH=O) CH₂CH₂Si (CH₃) ₂OSi (CH₃ ) ₂CH₂CH₂CH (CH₂CH=O) CH₂ CH₂CH₂OH, and the like. The silicon-containing organic groups are not limited thereto.

The microparticles of the metal or metal oxide of the present invention, in which the silicon-containing organic group represented by general formula (A) is fixed on the surface of the microparticles by means of chemical bonding can be produced by reacting a silicon-containing compound and an aqueous solution or aqueous dispersion of a metal salt under conditions at a temperature of not less than 300⁰C under pressure of not less than 10 MPa.

The silicon-containing compounds are not particularly limited as long as the compounds contain silicon, and are preferably organic compounds including a silicon atom or atoms such as organosilane, organodisiloxane, organopolysiloxane and the like. In particular, the aforementioned silicon-containing compound preferably has at least one monovalent organic group having a hydrolyzable group or a condensation-reactive group, or a reactive functional group. As examples of the monovalent organic group having a hydrolyzable group or a condensation- reactive group, or a reactive functional group, those described below can be mentioned. The aforementioned organic compounds containing silicon atoms may be used alone or in combination with two or more types thereof.

As the organosilane, a reactive silane represented by general formula (B) shown below is preferable.

R³SiR^W (B)

R³ represents a monovalent organic group having a reactive functional group;

W represents a hydrolyzable group or condensation-reactive group selected from the group consisting of a hydrogen atom; a halogen atom; a group of a formula: -OR⁴ wherein R⁴ is a hydrogen atom or a substituted or unsubstituted monovalent hydrocarbon group having 4 or less carbon atoms; a group of a formula: -OC(O)R¹ wherein R¹ is the same as described above; a group of a formula:

wherein R¹ is the same as described above; a group of a formula: -NR⁵- C(O)R¹ wherein R¹ is the same as described above, and R⁵ is a hydrogen atom or a substituted or unsubstituted monovalent hydrocarbon group; and a group of a formula: - ONH₂. The organosilanes may be used alone or in combination with two or more types thereof. In general formula (B) , the substituted or unsubstituted monovalent hydrocarbon groups of R¹ are not particularly limited, and are typically, substituted or non-substituted, monovalent saturated hydrocarbon groups having 1 to 20 carbon atoms, preferably having 1 to 10 carbon atoms, and more preferably having 1 to 4 carbon atoms; monovalent aromatic hydrocarbon groups having 6 to 20 carbon atoms, and preferably having 6 to 12 carbon atoms; or monovalent unsaturated aliphatic hydrocarbon groups having 2 to 20 carbon atoms. Examples thereof may include the same groups as described above.

The monovalent organic group having a reactive functional group of R³ means a monovalent organic group having a hydroxyl group, a mercapto group (-SH), an epoxy group, an amino group,^" an amide group, an ester group, a carboxyl group, an isocyanate group or the like. As the aforementioned organic group, the aforementioned monovalent hydrocarbon groups or monovalent hydrocarbon groups containing at least one oxygen atom, sulfur atom or nitrogen atom in the main chain are preferable. As examples of monovalent organic groups having a reactive functional group, mention may be made of, for example, 3-hydroxypropyl, 3- ( 2-hydroxyethoxy) propyl , 3-mercaptopropyl , 2,3- epoxypropyl, 3 , 4-epoxybutyl , 4 , 5-epoxypentyl , 2- glycidoxyethyl , 3-glycidoxypropyl , 4-glycidoxybutyl , 2- (3, 4-epoxycyclohexyl) ethyl, 3- (3, 4-epoxycyclohexyl) propyl, aminopropyl, N-butylaminopropyl , N-cyclohexylaminopropyl , N, N-dibutylaminopropyl , 3- ( 2-aminoethoxy) propyl, 3- (2- aminoethylamino) propyl , 3-carboxypropyl , 10-carboxydecyl , and 3-isocyanatepropyl groups and the like. R³ forms, by means of a reaction in the preparation method of the present invention, a divalent linking group L in the aforementioned general formula (A) or a linking group containing the aforementioned linking group L as a part.

The hydrolyzable group or condensation-reactive group of W is selected from the group consisting of a hydrogen atom; a halogen atom; a group of a formula: -OR⁴ wherein R⁴ is a hydrogen atom or a substituted or unsubstituted monovalent hydrocarbon group having 4 or less carbon atoms; a group of a formula: -OC(O)R¹ wherein R¹ is the same as described above; a group of a formula: -O-N=CR¹2 wherein R¹ is the same as described above; a group of a formula: -NR⁵-C(O)R¹ wherein R¹ is the same as described above, and R⁵ is a hydrogen atom or a substituted or unsubstituted monovalent hydrocarbon group; and a group of a formula: -ONH₂. As examples of halogen atoms, mention may be made of fluorine, chlorine, bromine, and iodine atoms. Examples of monovalent hydrocarbon groups of R¹ and R⁵ may include the same groups as those of R¹. Examples of monovalent hydrocarbon groups of R⁴ may include the same groups as described above. As examples of the aforementioned hydrolyzable group or condensation-reactive group of W, mention may be made of fluorine atom, chlorine atom, bromine atom, iodine atom, hydrogen atom, -OH, -OCH₃, -OCH₂CH₃, -OC(O)CH₃, -OC(O)CH₂CH₃, -0-N=C (CH₃) 2, -0-N=C(CH₃)CH₂CH₃, -NH-C(O)CH₃, -N(CH₃)-C(O)CH₃, -N(CH₃J-C(O)CH₂CH₃, -ONH₂ and the like.

As examples of preferable reactive silanes, mention may be made of, for example, 3-hydroxypropyldimethylhydroxysilane, 3-mercaptopropyldimethylhydroxysilane , 3- glycidoxypropyldimethylhydroxysilane and the like.

As the organopolysiloxanes , a linear reactive organopolysiloxane represented by general formula (C) shown below is preferable,

R⁶RSSiO- (SiR⁶R¹O)

(C)

wherein each R¹ independently represents a substituted or unsubstituted monovalent hydrocarbon group; each R⁶ independently represents a hydrolyzable group or condensation-reactive group selected from the group consisting of a hydrogen atom; a halogen atom; a group of a formula: -OR⁴ wherein R⁴ is a hydrogen atom or a substituted or unsubstituted monovalent hydrocarbon group having 4 or less carbon atoms; a group of a formula: -OC(O)R¹ wherein R¹ is the same as described above; a group of a formula: -O-N=CR¹ ₂ wherein R¹ is the same as described above; a group of a formula: -NR⁵-C(0)R¹ wherein R¹ is the same as described above, and R⁵ is a hydrogen atom or a substituted or unsubstituted monovalent hydrocarbon group; and a group of a formula: -ONH₂, a substituted or unsubstituted monovalent hydrocarbon group, or a monovalent organic group having a reactive functional group, with the proviso that at least one R⁶ is said hydrolyzable group or condensation-reactive group, or said monovalent organic group; and s is a number of 0 or more. The organopolysiloxanes may be used alone or in combination with two or more types thereof

In general formula (C), the substituted or unsubstituted monovalent hydrocarbon groups of R¹ are not particularly limited, and are typically, substituted or non-substituted, monovalent saturated hydrocarbon groups having 1 to 20 carbon atoms, preferably having 1 to 10 carbon atoms, and more preferably having 1 to 4 carbon atoms; monovalent aromatic hydrocarbon groups having 6 to 20 carbon atoms, and preferably having 6 to 12 carbon atoms; or monovalent unsaturated aliphatic hydrocarbon groups having 2 to 20 carbon atoms. Examples of R¹ may include the same substituted or unsubstituted monovalent hydrocarbon groups as listed for the aforementioned R¹.

The hydrolyzable group or condensation-reactive group of R⁶ is selected from the group consisting of a hydrogen atom; a halogen atom; a group of a formula: -OR⁴ wherein R⁴ is a hydrogen atom or a substituted or unsubstituted monovalent hydrocarbon group having 4 or less carbon atoms; a group of a formula: -OC(O)R¹ wherein R¹ is the same as described above; a group of a formula: -O-N=CR¹ ₂ wherein R¹ is the same as described above; a group of a formula: -NR⁵-C(O)R¹ wherein R¹ is the same as described above, and R⁵ is a hydrogen atom or a substituted or unsubstituted monovalent hydrocarbon group; and a group of a formula: -ONH₂. As examples of halogen atoms, mention may be made of fluorine, chlorine, bromine, and iodine atoms. Examples of monovalent hydrocarbon groups of R¹ and R⁵ may include the same groups as those of R¹. Examples of monovalent hydrocarbon groups of R⁴ may include the same groups as described above. Examples of the aforementioned hydrolyzable group or condensation-reactive group of R⁶ may include the same groups as described in the aforementioned W.

The substituted or unsubstituted monovalent hydrocarbon groups of R⁶ are not particularly limited, and are typically, substituted or non-substituted, monovalent saturated hydrocarbon groups having 1 to 20 carbon atoms, preferably having 1 to 10 carbon atoms, and more preferably having 1 to 4 carbon atoms; monovalent aromatic hydrocarbon groups having 6 to 20 carbon atoms, and preferably having 6 to 12 carbon atoms; or monovalent unsaturated aliphatic hydrocarbon groups having 2 to 20 carbon atoms. Examples thereof may include the same groups as described above.

The monovalent organic group having a reactive functional group for R⁶ means a monovalent organic group having a hydroxyl group, a mercapto group (-SH), an epoxy group, an amino group, an amide group, an ester group, a carboxyl group, an isocyanate group, or the like. As the aforementioned organic group, the aforementioned monovalent hydrocarbon group, or a monovalent hydrocarbon group having at least one oxygen atom, sulfur atom, or nitrogen atom in the main chain is preferable. As examples of the monovalent organic group having a reactive functional group for R⁶, mention may be made of the same groups as those for the aforementioned R³.

As examples of preferable organopolysiloxanes , mention may be made of, for example, dimethylpolysiloxanes having a hydroxyl group or groups at one terminal or both terminals of the molecular chain, .dimethylpolysiloxanes having an aminopropyl group or groups at one terminal or both terminals of the molecular chain, dimethylpolysiloxanes having a 2- ( 3 , 4-epoxycyclohexyl ) ethyl group or groups at one terminal or both terminals of the molecular chain, and the like.

The types of metal salts contained in the aqueous solution or aqueous dispersion of a metal salt are not limited, and any metal salts can be used. As the metal salt, a water- soluble salt is preferable, and, a sulfate, nitrate, acetate, oxalate, hydrochloride, or oxychloride of a metal ranging from group IV to group XV of the periodic table of the elements is preferable. More particularly, titanium trichloride, zirconium oxychloride, vanadyl sulfate, iron nitrate, iron sulfate, cobalt nitrate, nickel nitrate, palladium acetate, copper nitrate, copper acetate, silver acetate, zinc nitrate, zinc acetate, zinc oxalate, aluminum nitrate, tin acetate, and the like. They can be used alone or in combination with two or more types thereof.

The ratio of the reaction amounts of the silicon-containing compound and the aqueous solution or aqueous dispersion of the metal salt is not particularly limited. The ratio of the silicon-containing compound with respect to 100% by weight of the metal produced from the metal salt is preferably not less than 10% by weight. If the aforementioned ratio is below 10% by weight, the ratio of the silicon-containing organic group fixed on the surface may be remarkably reduced. Therefore, this is not preferable .

In the preparation method of the present invention, the presence of water in the reaction system is essential. In other words, the present invention is characterized by reacting the silicon-containing compound and the metal salt at a temperature of 300⁰C or greater, and under pressure of 10 MPa or greater. A preferable reaction temperature is 330°C or greater, and a more preferable temperature is not less than 374⁰C which is the critical temperature of water. In addition, a preferable reaction pressure is 15 MPa or greater, and a more preferable pressure is not less than 22 MPa which is the critical pressure of water. Under the conditions at 300⁰C or greater under 10 MPa or greater, water is in a subcritical state or supercritical state, and a special reaction system can be formed. Here, supercritical state means a state of the critical temperature or greater, and the critical pressure or greater. Subcritical state means a state of the critical temperature or greater and less than the critical pressure, or alternatively, a state of less than the critical temperature and the critical pressure or greater.

In addition, in an aqueous solution or aqueous dispersion of the metal salt, an alcohol such as methanol, ethanol or the like; a glycol such as ethylene glycol, propylene glycol or the like; a carboxylic acid such as formic acid, acetic acid or the like; an aldehyde such as formaldehyde, acetaldehyde, or the like; a ketone such as acetone, methyl ethyl ketone or the like; a thiol such as methane thiol or the like; an amine such as methylamine, dimethylamine , or the like; ammonia; or a surfactant may be added, if necessary. The blending amount thereof preferably ranges from 0.1 to 20% by weight based on the total weight of the aqueous solution or aqueous dispersion, more preferably ranges from 0.1 to 10% by weight, and further preferably ranges from 0.1 to 5% by weight.

An apparatus for carrying out the preparation method of the present invention is not particularly limited, and a common apparatus in the art can be used.

Fig. 1 is a conceptual view showing one example of a batch- type reaction apparatus by which a preparation method of the present invention is carried out. In the apparatus shown in Fig. 1, a reaction tube formed from a strong material such as SUS 316 or the like, is charged with an aqueous solution or aqueous dispersion of a metal salt and a silicon-containing compound, and the reaction tube is then heated to a temperature not less than the critical temperature of water (for example, 400⁰C) by means of a heating means such as a salt bath or the like, so that water in the reaction system is in a supercritical state or a subcritical state. The metal salt, the silicon-containing compound and water in a supercritical state or a subcritical state are reacted for a specified period, and the reaction tube is then cooled to stop the reaction. The product in the reaction tube is recovered.

Fig. 2 is a conceptual view showing an example of a continuous reaction apparatus by which a preparation method of the present invention is carried out. In the apparatus shown in Fig. 2, an aqueous solution or aqueous dispersion of a metal salt is stored in a first tank 1, and is transported to a reactor 11 by means of a first pump 2 via a first line 3. In addition, a silicon-containing compound is stored in a second tank 4, and is transported to the reactor 11 by means of a second pump 5 via a second line 6. On the other hand, distilled water is stored in a third tank 7, and is transported to the reactor 11 by means of a third pump 8 via a third line 9. On the way to the third line 9, a heater 10 is provided, and distilled water in the third line 9 is subjected here to high temperature and high pressure. Water in the third line 9 which is in a supercritical state or a subcritical state joins together with the aqueous solution or aqueous dispersion of a metal salt from the first line 3 and the mixture in the second line 6, and the reaction mixture is introduced into the reactor 11. While the reaction mixture passes through the reactor 11, a reaction is carried out. An aqueous reaction product at a high temperature under high pressure after the reaction is completed is discharged into the cooler 12. By the cooling step, the reaction is stopped. The product is recovered in a recovery tank 13. In the example shown in Fig. 2, the heater 10 is provided in the line 9, but an additional heater may also be provided in the line 3. In addition, the reactor 11 itself may be equipped with a heating and cooling mechanism. In addition, valves such as check valves or the like may be provided at suitable sites of the first line 3, the second line 6, and the third line 9.

In the preparation method of the present invention, water is basically used, and a large amount of an organic solvent is not used. For this reason, the burden on the environment is reduced, and at the same time, safety is exhibited. In addition, a complicated production apparatus is not required. For this reason, a large amount of microparticles of a metal or metal oxide having a silicon-containing organic group can be produced at reduced cost.

Industrial Applicability

The microparticles of a metal or metal oxide of the present invention can maintain a silicon-containing organic group with reactivity on the surface thereof, and for this reason, in the case of using them together with an organic material, and in particular, a silicon-based material such as polysiloxane, increased compatibility with the aforementioned organic material can be exhibited. Therefore, the microparticles of the metal or metal oxide of the present invention can be dispersed well in the silicon- based material.

The method for producing microparticles of a metal or metal oxide of the present invention does not use a large amount of an organic solvent. For this reason, the method can reduce the burden on the environment, and is safe. In addition, the method can be carried out by means of a simple device. For this reason, production cost can be controlled.

Microparticles of a metal or metal oxide of the present invention are used alone or in combination with an organic material, and can be applied in the fields of paints, pigments, cosmetics, catalysts, glass, medicines, and the like. For example, microparticles formed from copper of the present invention can be used as electrode materials, wiring materials, or catalyst materials. In particular, microparticles are preferably combined with a silicon-based organic material such as polysiloxane or the like.

Examples

Hereinafter, the present invention is described in detail with reference to Examples and Comparative Examples. Identification of microparticles of a metal or metal oxide having a silicon-containing organic group was carried out in accordance with the following.

(Shape and Size of Microparticles)

The size of microparticles was calculated on the basis of the particles observed with the use of a scanning electron microscope (hereinafter, simply referred to as SEM) , JSM- 5600 manufactured by JEOL Ltd. In addition, in the case of microparticles of which the particle size could not be observed by means of an SEM, the size thereof were calculated in the same manner as described above with the use of a field-emission transmission electron microscope (hereinafter, simply referred to as TEM) , JEM-2010F manufactured by JEOL Ltd.

(Elementary Analysis of Microparticles)

Elementary analysis was carried out with the use of an EDX analyzer for use in SEM and TEM (hereinafter, simply referred to as EDX) , Oxford Link ISIS manufactured by Oxford Instruments KK. In addition, in order to identify types of metals, measurement of X-ray diffraction (hereinafter, simply referred to as XRD) was carried out with the use of an M03X manufactured by MacScience Company.

(Chemical Structure of Silicon-Containing Organic Group)

The chemical structure of the silicon-containing organic group on the microparticles of the metal or metal oxide was analyzed by measuring infrared absorption spectra (hereinafter, simply referred to as IR measurement) with the use of a Fourier transform infrared spectrophotometer FT/IR-5300, manufactured by Japan Spectroscopic Co., Ltd., and by measuring ¹³C- and ²⁹Si-NMR spectra (hereinafter, simply referred to as NMR measurements) in a solid state with the use of the high-resolution NMR analyzer AC 300 P, manufactured by Bruker Biospin Corp. In the NMR measurement, sodium 3-trimethylsilyl-l-propanesulfonate was used as a standard substance for calculating the NMR frequency shift values .

(Example 1)

A reaction tube made from SUS 316 having an inner diameter of 7.5 mm and a capacity of 5.0 cm³ was loaded with 1.7 ml of a 0.1 mol/1 aqueous solution of copper nitrate and 0.1 ml of bis [2- ( 3 , 4-epoxycyclohexyl ) ethyl] tetramethyldisiloxne, and then, the reaction tube was sealed. The reaction tube was placed in a salt bath heated to 400⁰C beforehand, and was heated. The pressure in the case of assuming that purified water was used was 30 MPa.

After the reaction was carried out for 5 minutes, the reaction was stopped by immersing the reaction tube into cooled water, and the reaction tube was opened. The reaction product was recovered by repeating washing with water and washing with dichloromethane twice. The obtained particles were red, and were distributed in a dichloromethane phase and at the interface of water and dichloromethane. An SEM photograph of the obtained particles is shown in Fig. 3. The particle size ranged from 0.5 to 1.0 μm. On the other hand, a TEM photograph of microparticles in a large amount is shown in Fig. 4. The average particle size ranged from 5 to 10 nm.

As a result of the analyses by means of the EDX, copper and silicon were observed throughout all parts of the microparticles as shown in Fig. 5, and it was confirmed that the silicon-containing organic groups were present throughout all parts of the microparticles. In addition, as a result of the XRD measurement, it was observed that the product was a metal, copper. In addition, as a result of the IR and NMR measurements, the absorption and resonance peaks shown below were observed, and it was confirmed that there was a silicon-containing organic group represented by a formula:

IR (cm^'1) : 3,365; 2,916; 1,427; 1,251; 1,045.

1¹3³C-NMR (ppm) : 207, 204, 75, 71, 51, 43 to 25, 16, 0.

(Example 2)

A reaction tube made from SUS 316 having an inner diameter of 7.5 mm and a capacity of 5.0 cm³ was loaded with 1.7 ml of a 0.1 mol/1 aqueous solution of copper nitrate and 0.1 ml of a polydimethylsiloxane having a silanol at both terminals (average degree of polymerization: 15), and then, the reaction tube was sealed. The reaction tube was placed in a salt bath heated to 400⁰C beforehand, and was heated. The pressure in the case of assuming that purified water was used was 30 MPa.

A reaction was carried out in the same manner as described in Example 1, and a reaction product was recovered. The obtained particles were black, and were distributed in a dichloromethane phase and at the interface of water and the dichloromethane phase. An SEM photograph of the obtained particles is shown in Fig. 6. The particle size ranged from 0.1 to 0.5 μm. On the other hand, a TEM photograph of the microparticles in a large amount observed is shown in Fig. 7. The average particle size was about 40 nm.

As a result of the analyses by means of the EDX, copper, silicon and oxygen were observed throughout all parts of the microparticles as shown in Fig. 8, and it was confirmed that the silicon-containing organic groups were present throughout all parts of the microparticles. In addition, as a result of the XRD measurement, it was observed that the product was copper (II) oxide. In addition, as a result of the IR and NMR measurements, the absorption and resonance peaks shown below were observed, and it was confirmed that there was a silicon-containing organic group represented by a formula:

-OCH₂CH₂CH₂Si (CH₃) ₂0Si (CH₃) ₂CH₂CH₂CH₂OH

IR (cm^"1) : 3,360; 2,958; 1,425; 1,252; 1,050

1¹3³/C-NMR (ppm) : 74, 71, 28, 27, 16, 0.

(Example 3)

A reaction tube made from SUS 316 having an inner diameter of 7.5 mm and a capacity of 5.0 cm³ was loaded with 1.7 ml of a 0.1 mol/1 aqueous solution of copper nitrate and 0.1 ml of bis (aminopropyl ) tetramethyldisiloxane, and then, the reaction tube was sealed. The reaction tube was placed in a salt bath heated to 400°C beforehand, and heated. The pressure in the case of assuming that purified water was used was 30 MPa.

A reaction was carried out in the same manner as described in Example 1, and a reaction product was recovered. The obtained particles were red, and were distributed in a dichloromethane phase and at the interface of water and the dichloromethane phase. The average particle size of the obtained particles in accordance with SEM was 200 nm.

As a result of the analyses by means of the EDX, copper, silicon and oxygen were observed throughout all parts of the microparticles , and it was confirmed that the silicon- containing organic groups were present throughout all parts of the microparticles. In addition, as a result of the XRD measurement, it was observed that the product was a metal, copper. In addition, as a result of the IR and NMR measurements, the absorption and resonance peaks shown below were observed, and it was confirmed that there was a silicon-containing organic group represented by a formula:

-NHCH₂CH₂CH₂Si (CH₃) ₂OSi (CH₃) ₂CH₂CH₂CH₂NH₂

IR (cm^"1) : 3,365; 2,958; 1,420; 1,250; 1,052. 1³C-NMR (ppm) : 46, 42, 32, 31, 12, 0. 2⁹Si-NMR (ppm) : 7.6.

(Example 4)

A reaction and recovery of a product were carried out in the same manner as described in Example 1, with the exception of using 1.7 ml of a 0.01 mol/1 aqueous solution of nickel nitrate. The obtained particles were gray, and were distributed in a dichloromethane phase and at the interface of water and the dichloromethane phase. The average particle size of the obtained particles in accordance with SEM was 100 nm. As a result of the analyses by means of the EDX, nickel, silicon and oxygen were observed throughout all parts of the microparticles , and it was confirmed that the silicon- containing organic groups were present throughout all parts of the microparticles. In addition, as a result of the XRD measurement, it was observed that the product was nickel oxide. In addition, as a result of the IR and NMR measurements, the absorption and resonance peaks shown below were observed, and it was confirmed that there was a silicon-containing organic group represented by a formula:

IR (cm^'1) : 3,365; 2,918; 1,427; 1,251; 1,048.

¹³C-NMR (ppm) : 207, 204, 76, 72, 51, 43 to 26, 16, 0.

²⁹Si-NMR (ppm) : 7.5.

(Example 5)

A reaction and recovery of a product were carried out in the same manner as described in Example 1, with the exception of using 1.7 ml of a 0.01 mol/1 aqueous solution of iron nitrate. The obtained particles were dusky red, and were distributed in a dichloromethane phase and at the interface of water and the dichloromethane phase. The average particle size of the obtained particles in accordance with SEM was 30 nm.

As a result of the analyses by means of the EDX, iron, silicon and oxygen were observed throughout all parts of the microparticles, and it was confirmed that the silicon- containing organic groups were present throughout all parts of the microparticles. In addition, as a result of the XRD measurement, it was observed that the product was iron (III) oxide. In addition, as a result of the IR and NMR measurements, the absorption and resonance peaks shown below were observed, and it was confirmed that there was a silicon-containing organic group represented by a formula:

O— / V-CH₂CH₂Si(CH₃J₂OH

IR (cm^'1) : 3, 360; 2, 916; 1, 426; 1, 250; 1, 045. 1³C-NMR (ppm) : 207, 77, 51, 45 to 26, 16, 0, -0.5. 2⁹Si-NMR (ppm) : 16.5.

(Example 6)

A reaction and recovery of a product were carried out in the same manner as described in Example 1, with the exception of using 1.7 ml of a 0.01 mol/1 aqueous solution of zinc nitrate. The obtained particles were white, and were distributed in a dichloromethane phase and at the interface of water and the dichloromethane phase. The obtained particles were in the form of needles, and the average length of the short axis of the obtained particles in accordance with SEM was 100 nm.

As a result of the analyses by means of the EDX, zinc, silicon and oxygen were observed throughout all parts of the microparticles , and it was confirmed that the silicon- containing organic groups were present throughout all parts of the microparticles. In addition, as a result of the XRD measurement, it was observed that the product was zinc oxide. In addition, as a result of the IR and NMR measurements, the absorption and resonance peaks shown below were observed, and it was confirmed that there was a silicon-containing organic group represented by a formula:

IR (cm^"1) : 3, 365; 2, 916; 1, 424; 1, 250; 1, 048.

¹³C-NMR (ppm) : 207, 203, 75, 72, 51, 44 to 26, 16, 0.

²⁹Si-NMR (ppm) : 7.5.

(Comparative Example 1)

A reaction was carried out in the same manner as described in Example 1, with the exception of replacing bis [2- (3,4- epoxycyclohexyl) ethyl] tetramethyldisiloxane with 1-hexanol. A small amount of colored components were observed at the interface of water and the dichloromethane phase. However, few particles were produced.

(Comparative Example 2)

A reaction was carried out in the same manner as described in Example 1, with the exception of replacing bis [2- (3,4- epoxycyclohexyl) ethyl] tetramethyldisiloxane with hexamethyldisiloxane . The obtained particles were black. As a result of the IR measurement, the absorption peaks assigned to an organic group were not observed. Therefore, it was confirmed that no silicon-containing organic groups were fixed on the surface of the particles.

Claims

1. Micropart icle of a metal or metal oxide on the surface of which a silicon-containing organic group is fixed by means of a chemical bonding wherein the silicon- containing organic group is represented by general formula (A) shown below:

-LpSiR¹ _qX₍4-p-_q) (A)

wherein each R¹ independently represents a substituted or unsubstituted monovalent hydrocarbon group; L represents a divalent linking group of a formula: - (YC_xH_2x) _t (C_xH₂χ-yZ_zO_w) _v- wherein Y is -0-, -S-, or a formula: -NR²- wherein R² is a hydrogen atom or a substituted or unsubstituted monovalent hydrocarbon group, Z is -NH- or -N(CH₃)-, x is an integer ranging from 3 to 20, y is an integer ranging from 0 to 5, z is 0 or 1, w is an integer ranging from 0 to 5, t is an integer ranging from 0 to 50, and v is 0 or 1; p and q are respectively numbers that satisfy the following conditions: 0 < p ≤ 2 ; 0 < q ≤ 2; and 2 ≤ p + q < 4 ; and

X represents a group of a formula: - (OSiRS) _r~K wherein R¹ is the same as described above, K is HO- or a monovalent group of a formula: H (YC_xH_2x) t (C_xH2_X-_yZ_zO_w) _v- wherein Y, Z, x, y, z, w, t, and v are the same as described above, and r is a number of 0 or more.

2. A method for producing microparticles of a metal or metal oxide recited in Claim 1, comprising reacting a silicon-containing compound and an aqueous solution or aqueous dispersion of a metal salt under conditions at a temperature of not less than 300⁰C under pressure of not less than 10 MPa.

3. The method according to Claim 2, wherein the silicon- containing compound is a reactive silane represented by general formula (B) shown below:

R³SiR^W (B)

wherein each R¹ independently represents a substituted or unsubstituted monovalent hydrocarbon group; R³ represents a monovalent organic group having a reactive functional group;

W represents a hydrolyzable group or condensation- reactive group selected from the group consisting of a hydrogen atom; a halogen atom; a group of a formula: -OR⁴ wherein R⁴ is a hydrogen atom or a substituted or unsubstituted monovalent hydrocarbon group having 4 or less carbon atoms; a group of a formula: -OC(O)R¹ wherein R¹ is the same as described above; a group of a formula: -O-N=CR¹ ₂ wherein R¹ is the same as described above; a group of a formula: -NR⁵-C(O)R¹ wherein R¹ is the same as described above, and R⁵ is a hydrogen atom or a substituted or unsubstituted monovalent hydrocarbon group; and a group of a formula: -ONH₂.

4. The method according to Claim 2, wherein the silicon- containing compound is a linear reactive organopolysiloxane represented by general formula (C) shown below: R⁶RSSiO- (SiR⁶R¹O) s-SiR^R⁶ (C)

wherein each R¹ independently represents a substituted or unsubstituted monovalent hydrocarbon group; each R⁶ independently represents a hydrolyzable group or condensation-reactive group selected from the group consisting of a hydrogen atom; a halogen atom; a group of a formula: -OR⁴ wherein R⁴ is a hydrogen atom or a substituted or unsubstituted monovalent hydrocarbon group having 4 or less carbon atoms; a group of a formula: -OC(O)R¹ wherein R¹ is the same as described above; a group of a formula: -0-N=CR¹^ wherein R¹ is the same as described above; a group of a formula: -NR⁵-C(0)R¹ wherein R¹ is the same as described above, and R⁵ is a hydrogen atom or a substituted or unsubstituted monovalent hydrocarbon group; and a group of a formula: -ONH₂, a substituted or unsubstituted monovalent hydrocarbon group, or a monovalent organic group having a reactive functional group, with the proviso that at least one R⁶ is said hydrolyzable group or condensation-reactive group, or said monovalent organic group; and s is a number of 0 or more.

5. The method according to Claim 3 or 4, wherein the reactive functional group is selected from the group consisting of hydroxyl, mercapto, epoxy, amino, amide, ester, carboxyl, and isocyanate groups.

6. The method according to Claim 2, wherein the metal salt is a sulfate, nitrate, acetate, oxalate, hydrochloride, or oxychloride of a metal ranging from group IV to group XV of the periodic table of the elements.

7. The method according to Claim 2, wherein the silicon- containing compound is added in an amount of not less than 10% by weight with respect to 100% by weight of a metal produced from the metal salt.