WO2010073970A1

WO2010073970A1 - Polysiloxane composition and method for producing the same

Info

Publication number: WO2010073970A1
Application number: PCT/JP2009/071077
Authority: WO
Inventors: Takuya Ogawa; Yoshito Oshima
Original assignee: Dow Corning Toray Co., Ltd.; The University Of Tokyo
Priority date: 2008-12-24
Filing date: 2009-12-11
Publication date: 2010-07-01
Also published as: JP2010150321A

Abstract

A polysiloxane composition containing fine particles of a metal oxide on the surface of which an organosilicon group is present and a method for producing the same are provided. The polysiloxane composition contains a polysiloxane represented by average structural formula (A) and fine particles of a metal oxide on the surface of which an organosilicon group represented by general formula (B) is fixed by means of chemical binding, and a method for producing the aforementioned polysiloxane composition includes reacting fine particles of a metal oxide with an organosilicon compound having a silicon atom-binding hydrolyzable group or a silanol group, and a saturated or unsaturated monovalent organic group in the presence of water under conditions at a temperature of not less than 200°C, to simultaneously form the aforementioned polysiloxane and the aforementioned fine particles of the metal oxide.

Description

DESCRIPTION

POLYSILOXANE COMPOSITION AND METHOD FOR PRODUCING THE SAME

TECHNOLOGICAL FIELD

[0001] The present invention relates to a polysiloxane composition containing fine particles of a metal oxide having an organosilicon group on the surface thereof.

[0002] Priority is claimed on Japanese Patent Application No. 2008-327512, filed on December 24, 2008, the content of which is incorporated herein by reference.

BACKGROUND ART

[0003] Ultramicroparticles generally referred to as nanoparticles have increased surface energy, and for this reason, they exhibit properties different from conventional microparticles, such as changes in optical properties due to quantum size effects, reduction of melting points, increased catalytic properties, increased magnetic properties and the like. Therefore, ultramicroparticles are expected to be applied in various fields of electronic materials, optical materials, catalyst materials , illuminant materials , medicines and the like. However, the aforementioned ultramicroparticles very easily aggregate, and for this reason, modifying the surface thereof with an organic group is generally carried out. In addition, various methods for producing nanoparticles of which the surface is modified are known as described in Japanese Unexamined Patent Application, First Publication No. 2007-51188; Japanese Unexamined Patent Application, First Publication No. 2006-282503; Japanese Unexamined Patent Application, First Publication No. Hll-92687; and Japanese Unexamined Patent Application, First Publication No. H10-183207.

[0004] In order to exhibit useful properties of nanoparticles in polymer materials, it is necessary to disperse nanoparticles in the polymer materials without aggregating. Various methods therefor have been proposed. For example, Journal of the Society of Powder Technology, 40 (7), 487 - 96 (2003) proposes a method in which surface-modified silica nanoparticles are dispersed in a polymer by means of a biaxial extruder. In addition, Macromol. Mater. Eng . , 2003, 288, 717 - 723 reports a method in which nanoparticle production and dispersion thereof in a polymer are simultaneously carried out by a sol gel reaction between a nanoparticle precursor and a polymer having a hydrolyzable group. However, the aforementioned methods have problems in that the surface of the particles must be previously modified in an appropriate manner, and it is difficult to synthesize the hydrolyzable reactive polymers.

[0005] On the other hand, Japanese Unexamined Patent Application, First Publication No. H09-302257 describes complex microparticles in which microparticles are complexed with a polymer by means of a hydrolyzation and condensation reaction. In addition, Japanese Unexamined Patent Application, First Publication No. 2002-210356 describes complex microparticles in which microparticles are complexed with a polymer by using carbon dioxide under elevated pressure. However, even in these technologies, there are problems in that a long period of time is required in order to complete both steps of the synthesis of a polymer and the production of microparticles, and it is difficult to control the uniformity of a coating polymer layer. In addition, Japanese Examined Patent Application, Second Publication No. H06-47457 proposes a method for producing an organophilic silica having an organosilicon group on the surface thereof by slowly treating silica microparticles with a trialkoxysilane . However, there are problems in that an acid catalyst is required and a long period of time is required for the production. In addition, the aforementioned publication fails to describe a polysiloxane composition.

[0006] As described above, until the present time, a method for obtaining a composition in which nanoparticles are dispersed in a polymer by simultaneously carrying out a reaction of synthesizing the polymer and dispersing the nanoparticles in the polymer has not been reported.

Patent Document 1 Japanese Unexamined Patent Application, First Publication No. 2007-51188 Patent Document 2 Japanese Unexamined Patent Application, First Publication No. 2006-282503 Patent Document 3 Japanese Unexamined Patent Application, First Publication No. Hll-92687 Patent Document 4 Japanese Unexamined Patent Application, First Publication No. H10-183207 Non-Patent Document 1: Journal of the Society of Powder Technology, 40 (7) , 487 - 96 (2003) Non-Patent Document 2: Macromol. Mater. Eng . , 2003, 288, 717 - 723

Patent Document 5: Japanese Unexamined Patent Application, First Publication No. H09-302257 Patent Document 6 Japanese Unexamined Patent Application, First Publication No. 2002-210356 Patent Document 7 : Japanese Examined Patent Application, Second Publication No. H06-47457 DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention

[0007] The present invention is performed under the circumstances of the prior art described above, and the present invention has an objective to easily provide a composition in which fine particles of a metal oxide are suitably dispersed in a polymer.

Means for Solving the Problems

[0008] The objective of the present invention can be achieved by reacting fine particles of a metal oxide and an organosilicon compound having a substituted or unsubstituted monovalent organic group and having a silicon atom-binding hydrolyzable group or a silanol group in the presence of water under conditions at a temperature of not less than 200°C.

[0009] The composition provided by the present invention comprises a polysiloxane and fine particles of a metal oxide on the surface of which an organosilicon group is fixed via an oxygen atom in the aforementioned organosilicon group by means of chemical binding. The aforementioned polysiloxane is represented by average structural formula (A) shown below:

R _mX_nS iO [ ( 4 -m-n ) /2 ] ( A ) where in each R¹ independently represents a substituted or unsubstituted monovalent hydrocarbon group; each X independently represents a silicon atom-binding hydrolyzable group or a silanol group; and m and n are respectively numbers that satisfy the following conditions: 0 < m; 0 < n; and m + n < 3, and the aforementioned organosilicon group is represented by average structural formula (B) shown below:

R pXqS i O [ ( 4 -p-q ) / 2 ] ( B ) whe re in

R¹ and X are the same as described above; and p and q are respectively numbers that satisfy the following conditions: 0 < p; 0 <_ q; and p + q < 3.

[0010] The aforementioned organosilicon compound is preferably a reactive silane represented by general formula (C) shown below : R _aSiX (4-a) (C ) wherein

R¹ and X are the same as described above; and a is a number that satisfies the following condition: 0 < a £

2, and/ or a linear reactive organosiloxane oligomer repre sented by general f ormula ( D ) shown be low :

R^R²S iO- ( S iR¹R²O ) ₃- SiRSR² ( D ) wherein

R¹ is the same as described above; each R² independently represents a substituted or unsubstituted monovalent hydrocarbon group, or a silicon atom-binding hydrolyzable group or a silanol group; and s is a number that satisfies the following condition: 0 < s, and/or a branched or network-patterned siloxane represented by general formula (E) shown below:

R¹ _bX_cSi0_{[ (}4-b-c)/2) (E) wherein

R¹ and X are the same as described above; and b and c are respectively numbers that satisfy the following condit ions : 0 < b < 2 ; 0 < c < 2 ; and b + c < 2 .

[0011] The aforementioned hydrolyzable group or silanol group is preferably a group selected from the group consisting of a halogen atom, a hydrogen atom, a group of a formula: -OR³ wherein R³ is a hydrogen atom or a substituted or unsubstituted monovalent hydrocarbon group having 6 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: -NR⁴-C(O)R¹ wherein R¹ is the same as described above and R⁴ represents a hydrogen atom or a substituted or unsubstituted monovalent hydrocarbon group; and a group of a formula : -ONH₂.

[0012] The aforementioned metal oxide is preferably an oxide of a metal ranging from group IV to group XV of the periodic table of the elements.

[0013] The ratio by amount (weight) of the aforementioned polysiloxane and the fine particles of a metal oxide preferably ranges from 1:99 to 99:1.

Effects of the Invention [0014] In the polysiloxane compositions obtainable or obtained in the present invention, fine particles of a metal oxide are well dispersed in the polysiloxane. For this reason, the aforementioned polysiloxane compositions can exhibit characteristics originating from the aforementioned fine particles well. In particular, in addition to superior optical transparency, electrical insulation, optical stability, thermal stability, and cold resistance which the polysiloxane possesses, properties of the aforementioned particles can be exhibited .

[0015] The method for producing the polysiloxane composition according to the present invention does not use a large amount of an organic solvent. For this reason, the method can reduce load on the environment, and is safe. In addition, the method can be carried out by means of a simple device. For this reason, production costs can be controlled. In addition, the polysiloxane can be synthesized without using an acid catalyst or a base catalyst.

[0016] In addition, in the method for producing the polysiloxane composition according to the present invention, by simultaneously carrying out the reaction of synthesizing the polymer and the reaction for modifying the surface of the fine particles, the polysiloxane and the fine particles of the metal oxide having the compatibility with the polysiloxane can be produced once. In addition, the fine particles can be dispersed well in the polysiloxane.

Best Modes for Carrying Out the Invention

[0017] The polysiloxane composition obtainable or obtained by the present invention contains, as essential components,

(a) a polysiloxane represented by average structural formula (A) shown below:

R _mX_nS iO [ ( 4 -m-n ) _/2 ] ( A ) whe rein each R¹ independently represents a substituted or unsubstituted monovalent hydrocarbon group; each X independently represents a silicon atom-binding hydrolyzable group or a silanol group; and m and n are respectively numbers that satisfy the following conditions: 0 < m; 0 < n; and m + n < 3, and

(b) fine particles of a metal oxide on the surface of which an organosilicon group is fixed via an oxygen atom in the aforementioned organosilicon group by means of chemical binding wherein the organosilicon group is represented by average structural formula (B) shown below:

R _pXqS i O [ ( 4 -p-q ) /2 ] ( B ) wherein

R¹ and X are the same as described above; and p and q are respectively numbers that satisfy the following conditions: 0 < p; 0 £ q; and p + q < 3.

[0018] In average structural formula (A) representing the aforementioned polysiloxane (a), the monovalent hydrocarbon group of R¹ is typically 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.

[0019] As examples of monovalent saturated hydrocarbon groups having 1 to 20 carbon atoms, mention may be made of, for example, linear 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 cyclopentyl, cyclohexyl, cycloheptyl, and cyclooctyl groups.

[0020] As examples of monovalent aromatic hydrocarbon groups having 6 to 20 carbon atoms, mention may be made of, for example, aryl groups such as 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 aliphatic 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, aralkyl groups such as benzyl and phenethyl groups.

[0021] As examples of monovalent unsaturated aliphatic hydrocarbon groups having 2 to 20 carbon atoms, mention may be made of, for example, linear or branched alkenyl groups such as vinyl, 1-propenyl, allyl, isopropenyl, 1-butenyl, 2-butenyl, pentenyl, and hexenyl groups; cycloalkenyl groups such as cyclopentenyl , and cyclohexenyl groups; and cycloalkenylalkyl groups such as cyclopentenylethyl , cyclohexenylethyl , and cyclohexenylpropyl groups. A vinyl group and a cyclohexenylethyl group are preferable.

[0022] The hydrogen atom on the aforementioned monovalent hydrocarbon group may be substituted by one or more substituent s , and the aforementioned substituents are selected from halogen atoms (fluorine, chlorine, bromine and iodine atoms) .

[0023] In addition, each X is independently a silicon atom-binding hydrolyzable group or a silanol group, and is a group preferably selected from the group consisting of a halogen atom, a hydrogen atom, a group of a formula: -OR³ wherein R³ is a hydrogen atom or a substituted or unsubstituted monovalent hydrocarbon group having 6 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: -NR⁴-C (0) R¹ wherein R¹ is the same as described above and R⁴ represents a hydrogen atom or a substituted or unsubstituted monovalent hydrocarbon group; and a group of a formula : -ONH₂, although the aforementioned X is not limited thereto.

[0024] In addition, the monovalent hydrocarbon groups of R³ are not particularly limited. As examples thereof, mention may be made of, for example, linear or branched alkyl groups such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, and tert-butyl groups and cycloalkyl groups such as cyclopentyl and cyclohexyl groups. The hydrogen atoms on the aforementioned monovalent hydrocarbon groups may be substituted with one or more substituents. The aforementioned substituents are selected from halogen atoms (fluorine atom, chlorine atom, bromine atom, and iodine atom) . Preferable R³ is a hydrogen atom or a methyl group.

[0025] In addition, the monovalent hydrocarbon groups of R⁴ are not particularly limited. As examples thereof, mention may be made of, for example, the same monovalent hydrocarbon groups as described in the aforementioned R¹. Preferable R⁴ is a hydrogen atom or a methyl group.

[0026] The aforementioned polysiloxane (a) may be linear, branched, or network-patterned. In average structural formula (A) showing the aforementioned polysiloxane (a) , m and n are respectively numbers that satisfy the following conditions: 0 < m, 0 < n, and m + n < 3. When the value of m + n is not less than 2, the polysiloxane is linear, and when the value thereof is less than 2, the polysiloxane is branched or network-patterned. The aforementioned polysiloxane (a) has, for example, an alkoxy group and/or a hydroxyl group binding to a silicon atom. As examples of the aforementioned polysiloxanes (a) , mention may be made of, for example, linear diorganopolysiloxanes having alkoxy groups and/or hydroxyl groups binding to silicon atoms at both terminals of the molecular chain, linear diorganopolysiloxanes having alkoxy groups and/or hydroxyl groups binding to a silicon atom at one terminal of the molecular chain, linear diorganopolysiloxanes having alkoxy groups and/or hydroxyl groups binding to silicon atoms at a terminal of the molecular chain and at the pendant chain, cyclic diorganopolysiloxanes having alkoxy groups and/or hydroxyl groups binding to a silicon atom at the pendant chain, silicone resins having alkoxy groups and/or hydroxyl groups binding to silicon atoms, and the like.

[0027] The aforementioned fine particles (b) of a metal oxide are not particularly limited as long as an organosilicon group is fixed on the surface of the fine particles via the oxygen atom in the aforementioned organosilicon group by means of chemical binding. The organosilicon group is represented by average structural formula (B) shown below:

R _pXqS i O [ ( 4-p-q ) /2 ] ( B ) wherein

[0028] The metals forming the aforementioned metal oxide fine particles 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 elements on the line of boron (B) of group XIII - silicon (Si) of group XIV - arsenic (As) of group XV as well as those positioned at the right side of the elements of group IV and positioned at the left side and at the lower side of the aforementioned line of 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 and the like as 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, Mn, Fe, Ni, Cu, Zn, Al, Si, Ge and Sn are preferable, and Ti, Zr, Mn, Fe, Ni, Cu, Zn, Al and Si are particularly 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 Ti, Zr, Fe, Ni, Cu, Zn, Al, Si, Ge, Sn and the like, such as SiO₂, TiO₂, ZnO, SnO₂, Al₂O₃, AlOOH, MnO₂, NiO, Fe₂O₃, Fe₃O₄, ZrO₂, BaTiO₃, LiCoO₂, LiMn₂O₄, CuO, Cu₂O, as well as mixtures thereof. Al₂O₃, AlOOH, Cu₂O, CuO, SiO₂ and ZrO₂ are preferable.

[0029] The form of the aforementioned fine particles is not particularly limited, and may be in any form such as a sphere, spindle, prismatic column, cylinder, plate, needle, or the like. A spherical fine particle is preferable.

[0030] The aforementioned fine particles 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, further preferably 50 nm or less, still further preferably 30 nm or less, and in particular, preferably 15 nm or less. The aforementioned fine particles may be a mixture of fine particles having various particle sizes. Measurement of the average particle size can be carried out by means of a common measurement method in the art. For example, particle size is 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 .

[0031] In the aforementioned fine particles, the organosilicon group is fixed on the surface of fine particles of a metal oxide by means of chemical binding. Here, chemical binding means a strong binding due to covalent binding, ion binding or the like, and does not include a simple binding due to physical adsorption or the like.

[0032] As examples of the aforementioned organosilicon groups represented by general formula (B) , mention may be made of, for example, -0-(Si(C₆Hs)₂O)V-Si(C₆Hs)₂(OCH₃) wherein v is a number of 1 or more, -0- ( Si (C₆H₅) ₂0) _W-Si (C₆H₅) ₂ (OH) wherein w is a number of 1 or more, and the like. The organosilicon groups are not limited thereto.

[0033] The ratio of the aforementioned organosilicon group with respect to the metal oxide is not particularly limited, and preferably ranges from 1% by weight to 200% by weight and more preferably ranges from 5% by weight to 100% by weight. If the weight ratio of the organosilicon group is less than the lower limit of the aforementioned range, dispersibility of the fine particles of a metal oxide on the surface of which the organosilicon group is fixed by means of chemical binding, in the polysiloxane, may be impaired. On the other hand, if the weight ratio exceeds the upper limit of the aforementioned range, it may be difficult to provide useful properties such as thermal resistance and the like to the polysiloxane composition by the fine particles of a metal oxide.

[0034] The ratio of the amounts (weight) of the polysiloxane and the fine particles of a metal oxide onto which the organosilicon group is fixed by means of chemical binding in the polysiloxane composition of the present invention is not particularly limited. The ratio thereof preferably ranges from 1:99 to 99:1, and in particular, ranges from 4:96 to 96:4. If the weight ratio of the fine particles is less than 1% by weight, useful properties obtained by the aforementioned fine particles may not be sufficiently provided. On the other hand, if the weight ratio of the fine particles exceeds 99% by weight, good properties such as optical transparency, electrical insulation, molding processability and the like which the polysiloxane possesses may not be obtained.

[0035] The polysiloxane composition of the present invention can be produced by reacting an aqueous dispersion of the fine particles of a metal oxide with the organosilicon compound, or reacting the fine particles of a metal oxide, the organosilicon compound, and water under conditions at a temperature of not less than 200⁰C, to simultaneously form a polysiloxane and fine particles of the metal oxide on the surface of which the organosilicon group is fixed by means of chemical binding.

[0036] The organosilicon compounds are not particularly limited as long as compounds contain silicon, and are preferably organic compounds including silicon atoms such, as organosilanes , organosiloxane oligomers and the like. The aforementioned organic compounds containing silicon atoms may be used alone or in combination with two or more types thereof.

[0037] As the organosilane , an organosilane represented by general formula (C) shown below is preferable.

wherein

R¹ and X are the same as described above; and a is a number that satisfies the following condition: 0 < a <

2. The organosilanes may be used as a single type, or in combination with two or more types thereof. [0038] As preferable examples of organosilanes , mention may be made of, for example, dimethyldimethoxysilane, dimethyldiethoxysilane, methylvinyldimethoxysilane, methylphenyldimethoxysilane, methylchloropropyldimethoxysilane , methyltrimethoxysi lane , ethyltrimethoxysilane, vinyltrimethoxysi lane, phenyltrimethoxysilane, chloropropyltrimethoxysilane and the like.

[0039] As the organosiloxane oligomer, a linear organosiloxane oolligomer represented by general formula (D) shown below is preferable :

wherein

R¹ is the same as described above; each R² independently represents a substituted or unsubstituted monovalent hydrocarbon group, a silicon atom-binding hydrolyzable group or a silanol group, with the proviso that at least one R² in a molecule is the aforementioned hydrolyzable group or silanol group, and at least one R² in a molecule is the substituted or unsubstituted monovalent hydrocarbon group; and s is a number that satisfies the following condition: 0 < s.

As examples of the substituted or unsubstituted monovalent hydrocarbon group of R², mention may be made of the same groups as those of the aforementioned R¹. In addition, as examples of the silicon atom-binding hydrolyzable group or the silanol group, mention may be made of the same groups as those of the aforementioned X. The organosiloxane may be used as a single type or in combination with two or more types thereof.

[0040] As preferable examples of the organosiloxane oligomers, mention may be made of, for example, dimethylsiloxane oligomers having silicon atom-binding methoxy groups at both terminals of the molecular chain and at the pendant, dimethylsiloxane oligomers having hydroxyl groups at both terminals of the molecular chain and at the pendant, and the like.

[0041] In addition, as other organosiloxane oligomers, branched or network-patterned siloxanes represented by general formula (E) shown below are preferable:

R bXcS iO _f ( 4 -b-c) /2] ( E ) where in

R¹ and X are the same as described above; and b and c are respectively numbers that satisfy the following conditions: 0 < b < 2; 0 < c < 2; andb + c < 2. The organosiloxanes may be used as a single type or in combination of two or more types thereof.

[0042] In the method for producing the polysiloxane composition of the present invention, the fine particles of a metal oxide are used in the form of an aqueous dispersion in which they are preliminarily combined with water, or in the independent form in which water and the fine particles of the metal oxide are independently present.

[0043] The concentration of the fine particles of the metal oxide at the time of using the fine particles of the metal oxide in the form of an aqueous dispersion is not particularly limited. The concentration preferably ranges from 0.1% by weight to 50% by weight, and more preferably ranges from 1% by weight to 30% by weight, in view of efficiency of the production of the polysiloxane composition.

[0044] The mixing ratio of the organosilicon compound with respect to the aqueous dispersion of the fine particles of the metal oxide or the fine particles of the metal oxide and water is determined so that the ratio of the amounts (weight) of the polysiloxane and the fine particles of the metal oxide onto which the organosilicon group is fixed by means of chemical binding in the polysiloxane composition of the present invention preferably ranges from 1:99 to 99:1, and in particular, preferably ranges from 4:96 to 96:4. If the weight ratio of the fine particles of the metal oxide is less than the lower limit of the aforementioned range, useful properties obtained by the aforementioned fine particles may not be sufficiently provided. On the other hand, if the weight ratio of the fine particles exceeds the upper limit of the aforementioned range, good properties such as optical transparency, electrical insulation, molding processability and the like which the polysiloxane possesses may not be obtained.

[0045] In the method for producing a polysiloxane composition of the present invention, the presence of water in the reaction system is essential. 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 to water, if necessary. The blending amount thereof preferably ranges from 0.1 to 20% by weight based on the total weight of water and the metal oxide, more preferably ranges from 0.1 to 10% by weight, and further preferably ranges from 0.1 to 5% by weight. In the case of adding them in the aqueous dispersion of the fine particles of the metal oxide, dispersion stability and storage stability of the fine particles of the metal oxide can be improved.

[0046] A preferable reaction temperature in the preparation method of the present invention is 250⁰C or greater, and more preferably 300⁰C or greater . In addition, a preferable reaction pressure is 5 MPa or greater, and more preferably 10 MPa or greater .

[0047] In the preparation method of the present invention, the reaction period is not limited. An appropriate reaction period can be specified in accordance with a form and/or a size of an apparatus for carrying out the method, or in accordance with the rate of increasing the temperature of a reactor. If the rate of increasing the temperature of the reactor is increased, the reaction period may be decreased. On the other hand, if the rate of increasing the temperature of the reactor is decreased, in general, the reaction period is preferably increased.

[0048] The apparatus for carrying out the preparation method of the present invention is not particularly limited. For example, a common apparatus in the art such as a reaction tube formed from a strong material such as SUS 316 or the like can be used. More particularly, a reaction tube equipped with a thermometer or the like is charged with an aqueous dispersion of fine particles of a metal oxide, and an organosilicon compound, or alternatively, with fine particles of a metal oxide, an organosilicon compound and water. The reaction tube is then heated in order to specify the temperature in the reaction tube to not less than 200⁰C by means of a heating means such as a salt bath or the like to perform a reaction for a specified period. Subsequently, the reaction tube is cooled and a product in the reaction tube is recovered. Thereby, the preparation method of the present invention can be performed.

[0049] 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 polysiloxane compositions of the present invention can be produced at reduced cost.

[0050] The polysiloxane compositions of the present invention can be used alone or by adding other components thereto, and can be applied in the fields of paints, pigments, cosmetics, catalysts, glass, medicines, and the like. For example, the polysiloxane composition containing fine particles formed from silica of the present invention can be used as a thermal resistant coating material.

EXAMPLES

[0051] The polysiloxane compositions of the present invention and preparation methods thereof are described in detail with reference to Examples and Comparative Examples. Identification of the polysiloxane in a polysiloxane composition was carried out in accordance with the following method. In addition, identification of fine particles of a metal oxide on the surface of which an organosilicon group is fixed was carried out in accordance with the following method. Observation of dispersion conditions of fine particles of a metal oxide in the aforementioned composition was carried out in accordance with the following method.

[0052] Chemical Structure of the Polysiloxane

The chemical structure of the polysiloxane, which was a product, was analyzed by measuring infrared absorption spectra (hereinafter, simply referred to as IR) with the use of a Fourier transform infrared spectrophotometer FT/IR-5300, manufactured by Japan Spectroscopic Co., Ltd., and by measuring ²⁹Si-NMR spectra of the product in the form of a solid with the use of the high-resolution NMR analyzer AC 300 P, manufactured by Bruker Biospin Corp. In the NMR measurements, tetramethylsilane was used as a standard substance for calculating the NMR resonance frequency shift values.

[0053] Identification of Fine particles of Metal Oxide

The chemical structure of the organosilicon group fixed on the fine particles of the metal oxide was identified by the aforementioned measurement of IR spectra. The weight ratio thereof with respect to the fine particles of the metal oxide was obtained by means of thermogravimetric measurement (hereinafter, simply referred to as TGA) using TAS 200-TG 8110 D manufactured by Rigaku Corporation.

[0054] Dispersion Conditions of Fine particles of Metal Oxide

The dispersion conditions of a metal oxide on the surface of which an organosilicon group is fixed in the polysiloxane composition containing fine particles of the metal oxide, which was the product of the present invention, was observed by means of a transmission electron microscope (hereinafter, simply referred to as TEM) H-8100, manufactured by Hitachi Ltd. [0055] Example 1

A reaction tube made from SUS 316 having an inner diameter of 10.4 mm and a capacity of 10 cm³ was loaded with 0.84 ml of an aqueous dispersion of silica particles having an average particle size of 15 nm (PL-I; concentration of silica particles = 12% by weight, manufactured by Fuso Chemical Co., Ltd.) and 1.21 ml of phenyltrimethoxysilane, and then, the reaction tube was sealed. The reaction mixture was placed in a salt bath heated to 300°C beforehand, and was heated for 10 minutes. Subsequently, the reaction mixture was rapidly cooled in a water bath, and the reaction tube was opened. The reaction product was a phase separated mixture of white solids and a colorless transparent liquid. The separated solids were dried at 100⁰C under reduced pressure. Thereby, a product in the form of a white solid was obtained with an isolated yield of 92%. The solid was extracted with toluene . Thereby, a polysiloxane which was a soluble component and a silica on the surface of which an organosilicon group was fixed, which was an insoluble component, were separated.

[0056] From the spectral data shown below, it was confirmed that the soluble polysiloxane was a polysiloxane having an average structural formula shown below:

(C₆H₅) 1.0(R⁵O)O-I₆SiO_1-42 wherein R⁵ represents CH₃ or H.

IR (cm^"1) : 3,630; 3,480; 3,075; 3,020; 2,955; 2,865; 1,595; 1,436; 1,160; 925; 744; 700.

²⁹Si NMR: -70.0, -78.5.

[0057] From the IR spectrum of the silica on the surface of which the organosilicon group was fixed, the following absorption peaks were observed and it was confirmed that the structure of the organosilicon group was an average structural formula shown below :

(C₆H₅) 1.0(R⁵O)Ci₆SiOL₄₂ wherein R⁵ represents CH₃ or H.

IR (cm^"1) : 3,480; 1,638; 1,436; 1,160; 964; 805; 744; 700.

In addition, from the result of TGA, a ratio of the organosilicon group with respect to the silica was 25% by weight.

[0058] From the result of the TEM measurement of the product, it was confirmed that the silica fine particles in the form of almost spheres were dispersed in the polysiloxane without aggregating. The average particle size of the fine particles was 15 nm. It was confirmed that the size in the silica dispersion before the reaction was maintained.

[0059] In addition, the ratio of the weight of the silica fine particles on the surface of which the organosilicon group was fixed by means of chemical binding and the weight of the polysiloxane in the polysiloxane composition containing the fine particles of the metal oxide was 14:86.

[0060] Example 2

A reaction was carried out in the same manner as described in Example 1, with the exception of using 0.87 ml of an aqueous dispersion of silica particles having an average particle size ranging from 10 to 20 nm (SNOWTEX O; concentration of silica particles = 20% by weight, manufactured by Nissan Chemical Industries, Ltd.), as the aqueous dispersion of a metal oxide. Thereby, a phase separated mixture of white solids and a colorless transparent liquid was obtained. The separated solids were dried at 100⁰C under reduced pressure. Thereby, a product in the form of a white solid was obtained with an isolated yield of 94%. The solid was extracted with toluene. Thereby, a polysiloxane, which was a soluble component, and a silica on the surface of which an organosilicon group was fixed, which was an insoluble component, were separated.

[0061] From the spectral data shown below, it was confirmed that the soluble polysiloxane was a polysiloxane having an average structural formula shown below:

(C₆H₅) i.o (R⁵O) o.i2SiOi.₄₄ wherein R⁵ represents CH₃ or H.

IR (cm^"1) :3,628; 3,480; 3,076; 3,022; 2,950; 2,868; 1,595; 1,436; 1,155; 930; 744; 700.

²⁹Si NMR: -69.0; -78.0.

[0062] From the IR spectrum of the silica on the surface of which the organosilicon group was fixed, the following absorption peaks were observed and it was confirmed that the structure of the organosilicon group was an average structural formula shown below:

(C₆H₅)1.0(R⁵O)₀.1₂SiOi.₄₄ wherein R⁵ represents CH₃ or H.

IR (cm^"1) : 3,480; 1,637; 1,436; 1,155; 960; 805; 744; 700. n addition, from the result of TGA, a ratio of the organosilicon group with respect to the silica was 22% by weight.

[0063] From the result of the TEM measurement of the product, it could be confirmed that the silica fine particles in the form of almost spheres were dispersed in the polysiloxane without clumping. The average particle size of the fine particles ranged from 10 to 20 nm. It could be confirmed that the size in the silica dispersion before the reaction was maintained.

[0064] In addition, the ratio of the weight of the silica fine particles on the surface of which the organosilicon group was fixed by means of chemical binding and the weight of the polysiloxane in the polysiloxane composition containing the fine particles of the metal oxide was 23:77.

[0065] Example 3

A reaction was carried out in the same manner as described in Example 1, with the exception of using 2 ml of the aforementioned PL-I as the aqueous dispersion of the metal oxide and 0.042 ml of phenyltrimethoxysilane . Thereby, a phase separated mixture of white solids and a colorless transparent liquid was obtained. The separated solids were dried at 100⁰C under reduced pressure. Thereby, a product in the form of a white solid was obtained with an isolated yield of 94%. The solid was extracted with toluene. Thereby, a polysiloxane which was a soluble component and a silica on the surface of which an organosilicon group was fixed, which was an insoluble component, were separated.

[0066] From the spectral data shown below, it could be confirmed that the soluble polysiloxane was a polysiloxane having an average structural formula shown below:

(C₆H₅) i.o(R⁵0) o.ioSiOi.45 wherein R⁵ represents CH₃ or H.

IR (cm^"1) :3,630; 3,480; 3,076; 3,020; 2,955; 2,867; 1,595; 1,436; 1,158; 925; 744; 700.

[0067] From the IR spectrum of the silica on the surface of which the organosilicon group was fixed, the following absorption peaks were observed and it was confirmed that the structure of the organosilicon group was an average structural formula shown below :

(C₆H₅) 1.0 (R⁵O) o.ioSiOi.45 wherein R⁵ represents CH₃ or H. IR ( cm^{" 1} ) : 3 , 4 80 ; 1 , 638 ; 1 , 43 6 ; 1 , 158 ; 964 ; 805 ; 744 ; 700 .

In addition, from the result of TGA, a ratio of the organosilicon group with respect to the silica was 6% by weight.

[0068] From the result of the TEM measurement of the product, it was confirmed that the silica fine particles in the form of almost spheres were dispersed in the polysiloxane without aggregating. The average particle size of the fine particles was 15 nm. It was confirmed that the size in the silica dispersion before the reaction was maintained.

[0069] In addition, the ratio of the weight of the silica fine particles on the surface of which the organosilicon group was fixed by means of chemical binding and the weight of the polysiloxane in the polysiloxane composition containing the fine particles of the metal oxide was 96:4.

[0070] Example 4

A reaction was carried out in the same manner as described in Example 1, with the exception of using 0.26 g of silica fine particles having an average particle size of 25 nm and 1.89 ml of water instead of using 0.84 ml of the aqueous dispersion of silica particles having an average particle size of 15 nm, and using 0.38 ml of phenyltrimethoxysilane . Thereby, a phase separated mixture of white solids and a colorless transparent liquid was obtained. The separated solids were dried at 100⁰C under reduced pressure. Thereby, a product in the form of a white solid was obtained with an isolated yield of 92%. The solid was extracted with toluene. Thereby, a polysiloxane, which was a soluble component, and a silica on the surface of which an organosilicon group was fixed, which was an insoluble component, were separated.

[0071] From the spectral data shown below, it could be confirmed that the soluble polysiloxane was a polysiloxane having an average structural formula shown below:

(C₆H₅)Lo(R⁵O)Ci₆SiO_1-42 wherein R⁵ represents CH₃ or H.

IR (cm^"1) :3,630; 3,475; 3,076; 3,020; 2,955; 2,867; 1,595; 1,436; 1,158; 925; 744; 700.

²⁹Si NMR: -69.5; -78.5.

[0072] From the IR spectrum of the silica on the surface of which the organosilicon group was fixed, the following absorption peaks were observed and it was confirmed that the structure of the organosilicon group was an average structural formula shown below :

(C₆H₅) i.o (R⁵O) o.ieSiOi.42 wherein R⁵ represents CH₃ or H.

IR (cm^"1) : 3,475; 1,638; 1,436; 1,158; 964; 805; _^744; 700.

In addition, from the result of TGA, a ratio of the organosilicon group with respect to the silica was 9% by weight.

[0073] From the photograph of the TEM of the product, it could be confirmed that the silica fine particles in the form of spheres were dispersed in the polysiloxane without clumping. The average particle size of the fine particles was 25 nm. It could be confirmed that the size in the silica dispersion before the reaction was maintained.

[0074] In addition, the ratio of the weight of the silica fine particles on the surface of which the organosilicon group was fixed by means of chemical binding and the weight of the polysiloxane in the polysiloxane composition containing the fine particles of the metal oxide was 54:46.

[0075] Comparative Example 1

A reaction was carried out in the same manner as described in Example 1, with the exception of using a temperature of 175⁰C in the salt bath. Thereby, a product was obtained. The product was a mixture of two types of transparent liquids having different specific gravities. A polysiloxane in which a silica is dispersed could not be produced.

[0076] Comparative Example 2

A reaction was carried out in the same manner as described in Example 1, with the exception of using 0.58 ml of a dispersion of silica particles having an average particle size ranging from 10 to 20 nm in methyl isobutyl ketone (MIBK-ST; concentration of silica particles = 30% by weight, manufactured by Nissan Chemical Industries, Ltd.), instead of 0.84 ml of the aqueous dispersion of the silica particles having an average particle size of 15 nm. Thereby, a product was obtained. The product was a phase separated mixture of white solids and a transparent liquid. The separated solids were dried at 100°C under reduced pressure. Thereby, a white solid was obtained. The obtained product was a silica. A polysiloxane composition composed of a polysiloxane and fine particles of a metal oxide on the surface of which an organosilicon group was fixed by means of chemical binding was not produced.

Claims

A method for producing a polysiloxane composition comprising a polysiloxane represented by average structural formula (A) shown below:

R _mX_nS iO [ ( 4 -m-n ) /2 ] ( A ) where in each R¹ independently represents a substituted or unsubstituted monovalent hydrocarbon group; each X independently represents a silicon atom-binding hydrolyzable group or a silanol group; and m and n are respectively numbers that satisfy the following conditions: 0 < m; 0 < n; and m + n < 3, and fine particles of a metal oxide on the surface of which an organosilicon group is fixed via an oxygen atom in the aforementioned organosilicon group by means of chemical binding wherein the organosilicon group is represented by average structural formula (B) shown below:

R pX_qS i0 [ ( 4 -p-q) /2 ] ( B ) whe re in

R¹ and X are the same as described above; and p and q are respectively numbers that satisfy the following conditions: 0 < p; 0 <_ q; and p + q < 3, comprising reacting fine particles of a metal oxide and an organosilicon compound having a silicon atom-binding hydrolyzable group or a silanol group and a substituted or unsubstituted monovalent hydrocarbon group in the presence of water under conditions at a temperature of not less than

200⁰C.

The method for producing a polysiloxane composition according to claim 1, wherein the aforementioned organosilicon compound is an organosilane represented by general formula (C) shown below:

R¹SSiXi₄-S) (C) wherein each R¹ independently represents a substituted or unsubstituted monovalent hydrocarbon group; each X independently represents a silicon atom-binding hydrolyzable group or a silanol group; and a is a number that satisfies the following condition: 0 < a <

2.

3. The method for producing a polysiloxane composition according to claim 1, wherein the aforementioned organosilicon compound is a linear organosiloxane oligomer represented by general formula (D) shown below:

F^₂R²SiO- (SiR¹R²O) s-SiR^R² (D) wherein each R¹ independently represents a substituted or unsubstituted monovalent hydrocarbon group; each R² independently represents a substituted or unsubstituted monovalent hydrocarbon group, or a silicon atom-binding hydrolyzable group or a silanol group, with the proviso that at least one R² in a molecule is the aforementioned hydrolyzable group or a silanol group; and s is a number that satisfies the following condition: 0 < s .

4. The method for producing a polysiloxane composition according to claim 1, wherein the aforementioned organosilicon compound is a branched or network-patterned siloxane represented by general formula (E) shown below:

R¹ _bX_cSiO_{[ (4}-b-c)/2] (E) wherein each R¹ independently represents a substituted or unsubstituted monovalent hydrocarbon group; each X independently represents a silicon atom-binding hydrolyzable group or a silanol group; and b and c are respectively numbers that satisfy the following conditions : 0 < b < 2 ; 0 < c < 2 ; and b + c < 2 .

5. The method for producing a polysiloxane composition according to any one of claims 1 to 4, wherein the aforementioned silicon atom-binding hydrolyzable group or silanol group is a group selected from the group consisting of a halogen atom, a hydrogen atom, a group of a formula: -OR³ wherein R³ is a hydrogen atom or a substituted or unsubstituted monovalent hydrocarbon group having 6 or less carbon atoms, a group of a formula: -OC(O)R¹ wherein R¹ represents a substituted or unsubstituted monovalent hydrocarbon group, a group of a formula: -O-N=CR¹ ₂ wherein R¹ is the same as described above, a group of a formula: -NR⁴-C(O)R¹ wherein R¹ is the same as described above and R⁴ represents a hydrogen atom or a substituted or unsubstituted monovalent hydrocarbon group; and a group of a formula : -ONH₂.

6. The method for producing a polysiloxane composition according to any one of claims 1 to 5, wherein the aforementioned metal oxide is an oxide of a metal ranging from group IV to group XV of the periodic table of the elements .

7. A polysiloxane composition obtainable or obtained by the method for producing a polysiloxane composition as recited in any one of claims 1 to 6.

8. The polysiloxane composition according to claim 7, wherein a ratio by amount (weight) of the polysiloxane and the fine particles of a metal oxide ranges from 1:99 to 99:1.