JPH07267640A - Surface-modified titanium dioxide fine particle and method for producing the same - Google Patents

Abstract

PURPOSE:To obtain the titanium dioxide fine particles sufficiently reduced in surface activity, while the dispersibility of the titanium dioxide fine powder is improved, and capable of imparting an excellent UV light-shielding property without deteriorating transparency, by contact-treating the surfaces of the titanium dioxide fine particles with a specific organic silicon compound. CONSTITUTION:This titanium dioxide fine particles are obtained by contact- treating the surfaces of titanium dioxide fine particles with an organic silicon compound of formula I or II. The titanium dioxide fine particles comprise the titanium dioxide fine particles wherein the organic silicon groups of formula III or IV are bound to the Ti atoms of the surfaces through the oxygen atoms. In the formulas, R<1>, R<2>, R<3> are 1-3C methylene group; X is NH, O, S, CO, CH=CH, CidenticalC; R<4> is 1-3C alkyl; at least one of the three binding hands of Si is bound to Ti, and the others are bound to the Si of the adjacent organic silicon group.

Description

Detailed Description of the Invention

[0001]

INDUSTRIAL APPLICABILITY The present invention has suppressed surface activity and improved dispersibility. When incorporated into cosmetics, paints, resin films, etc., it decomposes and modifies other components. TECHNICAL FIELD The present invention relates to surface-modified titanium oxide fine particles capable of imparting excellent ultraviolet ray shielding properties without impairing transparency and a method for producing the same.

[0002]

2. Description of the Related Art Titanium oxide has a function of absorbing and scattering ultraviolet rays, and is therefore used by being blended with sunscreen cosmetics, paints, resin films and the like. However, since titanium oxide has high surface activity, it sometimes decomposes and modifies cosmetic ingredients and resin ingredients, and it is necessary to suppress the activity.

Therefore, the applicant of the present invention is, for example, Japanese Patent Publication No. 5-15.
In Japanese Patent No. 644, it is shown that the surface modification can be carried out at the level of ultrafine particles by producing ultrafine particles of a metal oxide which becomes a nucleus in a gas phase and immediately carrying out surface modification. However, in the case of this method, the suppression of the activity was not always sufficient because the surface coating was not perfect.

Next, Japanese Patent Laid-Open No. 5-70129 discloses that
During the hydrolysis of titanium alkoxide, NaOH and KCO ₃
It has been shown to suppress the activity by adding a basic compound such as and a hydrocarbon or silicone oil. However, such a treatment with a basic compound not only loses its effect when it is added to an aqueous solution and loses its effect, but also makes the aqueous solution strongly alkaline, which is problematic for use in cosmetics and the like.

Further, in Japanese Examined Patent Publication No. 1-31442,
By having an amino group and a hydrophobic group, a positive or zero-charged hydrophobic metal oxide fine powder is obtained, which is shown to be effective in improving the fluidity of the electrophotographic toner. Although there is no description of activity suppression in this publication, the present inventor repeated this technique and evaluated the activity, and found that the activity suppression was insufficient because a hydrophobic group was bonded. .

[0006]

DISCLOSURE OF THE INVENTION The present invention solves the above-mentioned conventional problems and improves the dispersibility of titanium oxide fine powder while sufficiently suppressing the surface activity and without impairing the transparency. It is an object of the present invention to provide surface-modified titanium oxide fine particles capable of imparting excellent ultraviolet shielding properties and a method for producing the same.

[0007]

That is, the first aspect of the present invention is
In addition, the oxygen of the general formula [I]

[Chemical 5] Or general formula [II]

[Chemical 6] [In the above formula, R ¹ , R ² and R ³ are each a carbon number of 1 to 3
X is -NH-, -O-, -S-,
It is a group selected from -CO-, -CH = CH- and -C≡C-, and at least one of three bonds of a silicon atom is bonded to a titanium atom via an oxygen atom, and Are bonded to silicon atoms of adjacent organic silicon groups. ] The surface-modified titanium oxide fine particles having an organic silicon group bonded thereto represented by the following are provided.

As described above, the first surface-modified titanium oxide fine particles of the present invention have the general formula [I] or the general formula [I] through the oxygen atoms in the titanium atoms on the surface of the titanium oxide fine particles.
[I] having an organic silicon group bonded thereto.

In the above general formula [I] or general formula [II], R ¹ , R ² and R ³ are each a methylene group having 1 to 3 carbon atoms. R ¹ in the general formula [I] and the general formula [II]
R ³ is preferably a methylene group having 3 carbon atoms. Further, R ² in the general formula [II] is preferably a methylene group having 2 carbon atoms. Next, in the general formula [II], X is —NH—, —O—, —S—, —CO—, —.
A group selected from CH = CH- and -C≡C-,
It is preferably -NH-.

That is, the organosilicon group represented by the general formula [I] is preferably ^{one in} which R ¹ is a methylene group having 3 carbon atoms. As the organosilicon group represented by the general formula [II], R ² is a methylene group having 2 carbon atoms, R ³ is a methylene group having 3 carbon atoms, and X is —NH—. Things are desirable.

As described above, the above general formula [I]
Alternatively, in the general formula [II], at least one of the three bonds of the silicon atom is bonded to the titanium atom via the oxygen atom, and the other is bonded to the silicon atom of the adjacent organic silicon group. It is particularly preferable that one of the three bonds of the silicon atom is bonded to the titanium atom and the other is bonded to the silicon atom of the adjacent organic silicon group.

[0012] As described above, the first surface-modified titanium oxide fine particles of the present invention have the general formula [I] or the general formula [I] through the oxygen atoms in the titanium atoms on the surface of the titanium oxide fine particles.
The organic silicon group represented by I] (organic silicon group having an amino group at the terminal) is bonded.

The titanium oxide fine particles may be crystalline (rutile type, anatase type) or amorphous (amorphous). As the titanium oxide fine particles, those having higher surface activity are more effective because the organic silicon compound is more likely to react. Especially amorphous
Titanium oxide contains a large amount of adsorbed water, easily reacts, and is highly effective. Such an amorphous
The titanium oxide can be produced by a gas phase hydrolysis method of a volatile titanium compound such as titanium alkoxide or titanium halide among known methods. As the titanium oxide fine particles, ultrafine particles are preferable, and the primary particle diameter thereof is 0.01 to 1 μm, particularly 0.01 to 0.1 μm.
Those with m are preferred.

The above-mentioned first surface-modified titanium oxide fine particles of the present invention can be suitably produced, for example, by the following method (second of the present invention).

That is, the surface of the titanium oxide fine particles is represented by the general formula [III]

[Chemical 7] Or general formula (IV)

[Chemical 8] [In the above formula, R ¹ , R ² and R ³ are each a carbon number of 1 to 3
X is -NH-, -O-, -S-,
It is a group selected from —CO—, —CH═CH— and —C≡C—, and R ⁴ is an alkyl group having 1 to 3 carbon atoms. ] The surface-modified titanium oxide fine particles according to the first aspect of the present invention can be efficiently produced by the contact treatment with the organosilicon compound represented by

In the general formula [III], R ¹ has ¹ carbon atom.
Is a methylene group having 3 to 3 carbon atoms, preferably a methylene group having 3 carbon atoms, and R ⁴ is an alkyl group having 1 to 3 carbon atoms, that is, a methyl group, an ethyl group or a propyl group, and preferably a methyl group or an ethyl group. . Specific examples of the organosilicon compound represented by the above general formula [III] include aminopropyltriethoxysilane, aminopropyltrimethoxysilane, aminoethyltriethoxysilane, aminomethyltriethoxysilane, aminomethyltrimethoxysilane,
Besides aminoethyltrimethoxysilane and the like, aminomethyltripropoxysilane, aminoethyltripropoxysilane and the like can be mentioned, and aminopropyltriethoxysilane is particularly preferable.

In the above general formula [IV], R ² is a methylene group having 1 to 3 carbon atoms, preferably a methylene group having 2 carbon atoms, and X is —NH—, —O—, —S—, -CO
A group selected from-, -CH = CH- and -C≡C-,
It is preferably —CO—, —CH═CH— or —NH—, particularly preferably —NH—, and R ³ has 1 carbon atom.
Is a methylene group having 3 to 3 carbon atoms, preferably a methylene group having 3 carbon atoms, and R ⁴ is an alkyl group having 1 to 3 carbon atoms, that is, a methyl group, an ethyl group or a propyl group, and preferably a methyl group or an ethyl group. .

Specific examples of the organosilicon compound represented by the above general formula [IV] include aminoethylaminopropyltrimethoxysilane, aminoethylaminopropyltriethoxysilane, aminopropylaminopropyltrimethoxysilane and aminopropylamino. Propyltriethoxysilane, Aminomethylaminopropyltrimethoxysilane, Aminomethylaminopropyltriethoxysilane, Aminoethylaminoethyltrimethoxysilane,
Aminoethylaminoethyltriethoxysilane, Aminoethylaminomethyltrimethoxysilane, Aminoethylaminomethyltriethoxysilane, Aminomethylaminomethyltrimethoxysilane, Aminomethylaminomethyltriethoxysilane, 6-Amino-3-oxo-hexyl Examples thereof include trimethoxysilane and 4-amino-2-butenyltrimethoxysilane, and aminoethylaminopropyltrimethoxysilane is particularly preferable.

In the method of the present invention, it is necessary to contact-treat the surface of the titanium oxide fine particles with the organosilicon compound represented by the above general formula [III] or general formula [IV]. As the titanium oxide fine particles, those mentioned above are used. In the method of the present invention, in the general formula [III] or the general formula [IV], an alkoxy group (OR
⁴ ) is hydrolyzed and bound to the hydroxyl groups on the surface of titanium oxide. The by-product is alcohol. In the method of the present invention, an organosilicon compound having an amino group at the terminal is used, and in the resulting surface-modified titanium oxide fine particles, the organosilicon group having an amino group at the terminal is fixed on the titanium oxide surface. Therefore, the surface-modified titanium oxide fine particles of the present invention do not release due to heating, dissolution, etc., and exhibit a stable activity suppressing effect. As an activity suppressing effect, it is considered that the basic amino group neutralizes the solid acid on the surface of titanium oxide.

When a volatile substance such as ammonia or amine is used as the basic substance for neutralizing the solid acid, it is liberated by heating or the like and a satisfactory effect cannot be obtained. In addition, Na, which is a non-volatile basic substance
When it is treated with OH, KCO ₃ or the like, it is dissolved and liberated when added to the aqueous solution, and the effect is lost, and the aqueous solution becomes a strong alkali, which is problematic for use in cosmetics and the like. Furthermore, instead of an amino group at the end, a chloro group (Cl-) or glycidoxy group

[Chemical 9] Then, there is no effect because it is not basic.

In the method of the present invention, as described above, the surface of the titanium oxide fine particles is treated with the general formula [III] or the general formula [IV].
The contact treatment is carried out with an organosilicon compound represented by (a terminal amino group-containing organosilicon compound). The contact treatment may be either vapor phase treatment or liquid phase treatment, but vapor phase treatment is more preferable.

In the vapor phase treatment, the organosilicon compound can be supplied by vapor or sprayed on titanium oxide, but it is preferable to supply and treat by vapor to prevent aggregation of titanium oxide. In particular, immediately after the production of titanium oxide in the vapor phase, it is most preferable that the vapor of the organosilicon compound is mixed and treated in the same manner in the vapor phase in order to prevent aggregation of the titanium oxide.

On the other hand, in the liquid phase method, treatment in an alcohol solvent is desirable, and a surfactant may be added to enhance dispersibility, or an acid or base may be added to accelerate hydrolysis. . In the liquid phase method, after the treatment, the target surface-modified titanium oxide fine particles can be obtained by filtering and drying the titanium oxide fine particles by an ordinary method such as filter filtration or spray drying.

Regarding the contact treatment, as described above, the vapor phase method is advantageous in that it prevents aggregation of titanium oxide, and the process is simple. The reaction temperature is room temperature to 4
00 ° C. is preferable, and a temperature of 100 ° C. or higher is particularly preferable because the reaction can be promoted. On the other hand, 40
When the temperature exceeds 0 ° C, the organosilicon compound is likely to be decomposed. Therefore, the more preferable reaction temperature is 2
It is 00-400 degreeC.

[0025]

EXAMPLES Next, the present invention will be described in detail with reference to Examples. EXAMPLE 1 Titanium tetraisopropoxide [Ti (OiC ₃ H _7)
4 ] at a flow rate of 2.4 g / hr, 0.17 Nm ³ / hr
It was introduced into a heater together with nitrogen gas and evaporated at 180 ° C. On the other hand, 8.5 g / hr of water was added to 0.16 Nm ³ / hr.
Introduced into the heater together with the nitrogen gas of, and evaporated to 500 ℃
Heated up. This heated steam and titanium tetraisopropoxide vapor are mixed in a reactor and titanium tetraisopropoxide is hydrolyzed at a temperature of 260 ° C. to produce ultrafine particulate titanium oxide (average particle diameter 0.02 μm). did. On the other hand, as a raw material for surface modification, aminopropyltriethoxysilane [NH ₂ C ₃ H ₆ Si (OC
₂ H ₅ ) ₃ ] at a flow rate of 0.2 g / hr and 0.17 Nm
^It was introduced into a heater together with nitrogen gas of ³ / hr and evaporated at 180 ° C. This vapor of aminopropyltriethoxysilane was introduced into the reactor, mixed with ultrafine particulate titanium oxide immediately after formation, and reacted at 260 ° C. to obtain surface-modified ultrafine particulate titanium oxide (surface modified oxidation Ultrafine titanium particles)
Got The residence time at this time was 0.4 seconds. Also, ethanol is detected in the exhaust gas after the reaction,
It was confirmed that aminopropyltriethoxysilane reacted with the hydroxyl groups on the surface of titanium oxide.

The surface-modified titanium oxide ultrafine particles thus obtained were evaluated for activity, dispersibility and liquid as follows. The results are shown in Tables 1 and 2.
Shown in the table. [Activity Evaluation] (Decomposition Rate of Isopropyl Alcohol) A glass tube having an inner diameter of 5 mm and containing 0.2 g of the surface-modified titanium oxide ultrafine particles obtained as described above was heated to 280 ° C., and helium gas was added at 80 ml / min. ． While flowing in, 3 μl of isopropyl alcohol (IPA) was injected, and the residual amount of IPA was analyzed by a gas chromatograph connected downstream, and the decomposition rate was calculated.

[Evaluation of Dispersibility] (Spectral Transmittance in Ethanol) 4 mg of the surface-modified titanium oxide ultrafine particles obtained as described above was added to 40 ml of ethanol, dispersed with an ultrasonic cleaner, and spectroscopically measured. Photometer (Hitachi, U-321
In (0), a cell having an optical path length of 10 mm was used and the spectral transmittance was measured using pure ethanol as a reference. FIG. 1 shows the spectral transmittance of untreated titanium oxide and the spectral transmittance of the surface-modified titanium oxide ultrafine particles obtained in Example 1.

[Evaluation of Liquidity] 1 g of the surface-modified titanium oxide ultrafine particles obtained as described above was suspended in 10 ml of distilled water while stirring and then filtered, and the pH of the filtrate was measured.

Reference Example 1 The same operation as in Example 1 was carried out except that titanium tetraisopropoxide was not supplied. At this time, ethanol was not detected in the exhaust gas, and it was confirmed that the gas phase hydrolysis reaction did not occur only with aminopropyltriethoxysilane.

Example 2 Aminoethylaminopropyltrimethoxysilane [NH ₂ C ₂ H ₄ NHC ₃ H ₆ Si was used as a raw material for surface modification.
The same operation as in Example 1 was performed, except that (OCH ₃ ) ₃ ] was supplied at a flow rate of 0.3 g / hr. The results are shown in Tables 1 and 2 and FIG.

Example 3 0.2 g of aminomethyltripropoxysilane [H ₂ NCH ₃ Si (OC ₃ H ₇ ) ₃ ] was used as a raw material for surface modification.
The same operation as in Example 1 was performed, except that the flow rate was / hr. The results are shown in Tables 1 and 2 and FIG.
Shown in.

Example 4 As a raw material for surface modification, 6-amino-3-oxo-hexyltrimethoxysilane [H ₂ NC ₃ H ₆ COC ₂ H _{4 was used.}
Si (OCH ₃ ) ₃ ] was supplied at a flow rate of 0.3 g / hr, and the same operation as in Example 1 was performed. The results are shown in Tables 1 and 2 and FIG.

Example 5 4-amino-2-butenyltrimethoxysilane [H ₂ NCH ₂ CH═CHCH ₂ Si was used as a surface-modifying raw material.
The same operation as in Example 1 was performed, except that (OCH ₃ ) ₃ ] was supplied at a flow rate of 0.3 g / hr. The results are shown in Tables 1 and 2 and FIG.

Comparative Example 1 Chloropropyltrimethoxysilane [ClC ₃ H ₆ Si (OCH ₃ ) ₃ ] 0.2 g /
The same operation as in Example 1 was performed except that the flow rate was hr. The results are shown in Tables 1 and 2 and FIG.

Comparative Example 2 Aminopropyltriethoxysilane having a flow rate of 0.2 g / hr and methyltriethoxysilane [CH ₃ Si (OC) having a flow rate of 0.2 g / hr were used as raw materials for surface modification.
₂ H ₅ ) ₃ ] was mixed and supplied.
The same operation was performed. The results are shown in Tables 1 and 2 and FIG. Comparing the results of Comparative Example 2 with the results of the Examples, the method of the present invention shows that the activity suppressing effect is better than that of the mixing treatment as shown in Comparative Example 2 (the mixing treatment performed in Japanese Patent Publication No. 1-31442). It turns out that is excellent.

Comparative Example 3 100 parts by weight of octamethylcyclotetrasiloxane was added to a solution prepared by diluting 100 parts by weight of titanium tetraisopropoxide with 500 parts by weight of isopropyl alcohol, and 50 parts by weight of water was added to 5 parts by weight of isopropyl alcohol while stirring.
Hydrolysis was performed by adding a solution diluted with 00 parts by weight. To this suspension, a solution prepared by dissolving 20 parts by weight of sodium hydroxide in a mixed solution of 20 parts by weight of water and 200 parts by weight of methanol was added and mixed, and then filtered and dried at 110 ° C. to obtain 40 parts by weight of A fine powder was obtained. The surface-modified ultrafine titanium oxide powder thus obtained was evaluated for activity, dispersibility and liquid in the same manner as in Example 1. The results are shown in Tables 1 and 2 and FIG.

[0037]

[Table 1]

[0038]

[Table 2]

From the results shown in Table 1, it can be seen that the surface-modified titanium oxide fine particles of the present invention have dramatically suppressed activity even under heating. Next, from the results of FIG. 1, FIG. 2 and FIG. 3, in the present invention, by covering the hydroxyl groups on the surface of the titanium oxide fine particles with the terminal amino group-containing organosilicon compound, it is possible to prevent the aggregation of powder particles. It can be seen that the transparency is improved when dispersed in ethanol, as compared with untreated titanium oxide. Further, it can be seen that the surface-modified titanium oxide fine particles of Comparative Example 3 manufactured by the liquid phase method have low transparency because they are aggregated during filtration and drying. Further, from the results of Table 2, surface-modified titanium oxide fine particles treated with a terminal amino group-containing organosilicon compound (Examples 1 to 1)
5) and the surface-modified titanium oxide fine particles treated with other organosilicon compounds (Comparative Examples 1 and 2) showed neutrality, but the surface-modified titanium oxide of Comparative Example 3 treated with a basic salt. It can be seen that the fine particles dissolve the basic salt and exhibit strong alkalinity.

[Comprehensive Evaluation] Summarizing the results shown in Tables 1 and 2 and FIGS. 1, 2 and 3, the surface-modified titanium oxide fine particles of the present invention are obtained by using the terminal amino group-containing organosilicon compound. To cover the hydroxyl groups on the surface of titanium oxide particles,
It is understood that the surface activity can be suppressed while improving the dispersibility of the titanium oxide fine particles, because the titanium oxide fine particles have an organic silicon group bonded to the surface thereof. Therefore, it can be seen that when added to cosmetics, paints, resins, etc., UV shielding properties can be imparted without decomposing other components and without impairing transparency.

[0041]

The first surface-modified titanium oxide fine particles of the present invention have the surface activity (solid acid activity) sufficiently suppressed while preventing aggregation. In addition, the first surface-modified titanium oxide fine particles of the present invention have improved dispersibility. Therefore, the first surface-modified titanium oxide fine particles of the present invention, when added to cosmetics, paints, resins, etc., do not decompose other components or cause deterioration, etc. It is possible to impart ultraviolet shielding properties without impairing it. Moreover, since the specific organic silicon group is bonded to the titanium oxide surface in the first surface-modified titanium oxide fine particles of the present invention, there is no problem of release of the treatment agent due to heating or dissolution. Further, the first surface-modified titanium oxide fine particles of the present invention are almost neutral and do not exhibit strong alkalinity. Furthermore, according to the second aspect of the present invention, the above-mentioned first surface-modified titanium oxide fine particles of the present invention can be efficiently produced. Therefore, the surface-modified titanium oxide fine particles of the present invention can be effectively used as cosmetics, paints, resin films, fibers and the like.

The various aspects of the present invention are as follows. (1). Via the oxygen atom to the titanium atom on the surface of the titanium oxide fine particles, the above general formula [I] or the above general formula [II]
[In the above formula, R ¹ , R ² and R ³ are each a carbon number of 1 to 3
X is -NH-, -O-, -S-,
It is a group selected from -CO-, -CH = CH- and -C≡C-, and at least one of three bonds of a silicon atom is bonded to a titanium atom via an oxygen atom, and Are bonded to silicon atoms of adjacent organic silicon groups. ] Surface-modified titanium oxide fine particles bonded with an organic silicon group represented by the following.

(2). The particle size of titanium oxide fine particles is 0.0
The surface-modified titanium oxide fine particles according to (1) above, which is 1 to 1 μm.

(3). The surface-modified titanium oxide fine particles according to (1), wherein R ¹ in the general formula [I] is a methylene group having 3 carbon atoms.

(4). The surface-modified titanium oxide fine particles according to (1), wherein R ² in the general formula [II] is a methylene group having 2 carbon atoms, and R ³ is a methylene group having 3 carbon atoms.

(5). X in the general formula [II] is-
The surface-modified titanium oxide fine particles according to (1) above, which is NH-.

(6). The surface-modified oxidation according to (1) above, wherein R ² in the general formula [II] is a methylene group having 2 carbon atoms, R ³ is a methylene group having 3 carbon atoms, and X is —NH—. Titanium particles.

(7). The above general formula [I] or general formula [I
In the above [1], one of the three bonds of the silicon atom is bonded to the titanium atom through the oxygen atom, and the other is bonded to the silicon atom of the adjacent organic silicon group (1. ) The surface-modified titanium oxide fine particles described above.

(8). The surface of the fine particles of titanium oxide is represented by the general formula [III] or the general formula [IV] [wherein R ¹ ,
R ² and R ³ are each a methylene group having 1 to 3 carbon atoms, and X is —NH—, —O—, —S—, —CO—, —CH.
A group selected from ═CH— and —C≡C—, and R ⁴
Is an alkyl group having 1 to 3 carbon atoms. ] The method for producing the surface-modified titanium oxide fine particles as described in (1) above, which comprises performing a contact treatment with an organosilicon compound represented by the following.

(9). The method according to (8) above, wherein the organosilicon compound is contacted with the titanium oxide fine particles in a vapor phase.

(10). The organosilicon compound represented by the general formula [III] is aminopropyltriethoxysilane [N
H ₂ C ₃ H ₆ Si (OC ₂ H ₅ ) ₃ ] above (8)
The method described.

(11). The organosilicon compound represented by the general formula [IV] is aminoethylaminopropyltrimethoxysilane [NH ₂ C ₂ H ₄ NHC ₃ H ₆ Si (OCH ₃ ).
₃ ] The method according to (8) above.

(12). The method according to (8) above, wherein the organosilicon compound is contacted with the titanium oxide fine particles in a vapor phase.

(13). As the contact treatment, the method according to (12) above, wherein the treatment is performed by supplying with steam.

(14). The method according to (12) above, wherein the contact treatment is performed at a temperature of room temperature to 400 ° C.

[Brief description of drawings]

FIG. 1 is a graph showing the spectral transmittances of surface-modified titanium oxide fine particles obtained in Example 1 of the present invention and Comparative Example 1 and untreated titanium oxide fine particles.

FIG. 2 is a graph showing the spectral transmittance of the surface-modified titanium oxide fine particles obtained in Example 2 of the present invention, Comparative Example 2 and Comparative Example 3.

FIG. 3 is a graph showing the spectral transmittance of the surface-modified titanium oxide fine particles obtained in Example 3, Example 4, and Example 5 of the present invention.

Claims (4)

[Claims] 1. A compound of the general formula [I]: wherein titanium atoms on the surface of titanium oxide fine particles are intervened by oxygen atoms. Or the general formula [II] [In the above formula, R ¹ , R ² and R ³ are each a carbon number of 1 to 3
X is -NH-, -O-, -S-,
It is a group selected from -CO-, -CH = CH- and -C≡C-, and at least one of three bonds of a silicon atom is bonded to a titanium atom via an oxygen atom, and Are bonded to silicon atoms of adjacent organic silicon groups. ] Surface-modified titanium oxide fine particles bonded with an organic silicon group represented by the following. 2. The particle size of titanium oxide fine particles is 0.01 to 1.
The surface-modified titanium oxide fine particles according to claim 1, which have a thickness of μm. 3. The surface of the titanium oxide fine particles is formed according to the general formula [II
I] [Chemical 3] Or the general formula [IV] [In the above formula, R ¹ , R ² and R ³ are each a carbon number of 1 to 3
X is -NH-, -O-, -S-,
It is a group selected from —CO—, —CH═CH— and —C≡C—, and R ⁴ is an alkyl group having 1 to 3 carbon atoms. ] The method for producing surface-modified titanium oxide fine particles according to claim 1, characterized in that a contact treatment is carried out with an organosilicon compound represented by the formula [1]. 4. The method according to claim 3, wherein the organosilicon compound is contacted with the titanium oxide fine particles in a vapor phase.