JPH03279210A - Organotitania-silica sol and production thereof - Google Patents

Abstract

PURPOSE:To obtain an organosol, excellent in ultraviolet ray absorptivity and transparency to visible rays and capable of enhancing the refractive index of sol particles by subjecting a partial condensate of a partial hydrolyzate from a silicon alkoxide with a titanium alkoxide to hydrolyzing and polycondensing reaction. CONSTITUTION:A partial condensate of a partial hydrolyzate from a silicon alkoxide expressed by formula I (R<1> is 1-4C alkyl) with a titanium alkoxide expressed by formula II (R<2> is 1-4C alkyl) is subjected to hydrolyzing and polycondensing reaction in the presence of an acidic catalyst in an organic solvent. Thereby an organotitania-silica sol in which titania-silica fine particles are dispersed in the organic solvent and the sol turbidity (tau) at 10wt.% concentra tion of the titania-silica fine particles is <=5cm<-1> when calculation is made by using an equation of tau=A.2X303 from the absorbance (A) at 430nm wave length measured with a spectrophotometer using a cell of 10mm optical path length and water as a reference with >=300nm ultraviolet absorption edge is obtained.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an organotitania-silica sol in which fine titania-silica particles are dispersed in an organic solvent, and more specifically, it has excellent ultraviolet absorption ability and It has excellent transparency to visible light, and the refractive index of titania-silica fine particles can be adjusted arbitrarily, making it suitable as an additive for various film-forming agents, especially as a filler for hard coating agents such as plastic lenses. The present invention relates to an organotitania-silica sol used and a method for producing the same.

[Problems to be solved by conventional techniques and inventions] Conventionally,
Metal oxide sols using an organic solvent as a dispersion medium, so-called organosols, include SiO□ sol, Ah03 sol, 5b
ZOs sol, TiOz sol, ZrO sol, etc. are known. These organosols are used for purposes such as modification of plastics and synthetic fibers, petroleum additives, and raw materials for high-purity fine ceramic powders.

Among the organosols mentioned above, SiO□ sol is SiO□
It is possible to arbitrarily control the particle size of the fine particles, and it is also possible to use water-dispersed silica sol to various organic solvents, such as methanol, ethanol, isopropanol, t-
It is possible to replace the solvent with butanol, ethylene glycol, glycerin, dimethylformamide, etc.
Since there are many varieties, it is currently used in large quantities.

However, in recent years, there has been a demand for organosols that have the property of absorbing ultraviolet rays, especially as additives for film-forming agents.
All conventional organosols are unsatisfactory for this field of application. That is, the above organosilica sol cannot be used because it transmits ultraviolet rays of 5t (h is 300 nm or less).In addition, other organosols,
For example, TiOz sol, ZrO, sol, etc. have the property of absorbing ultraviolet light of 300 nm or less, but due to the sol manufacturing method, it is difficult to obtain a sol with small particle size and low turbidity, and only large particle size can be obtained. I can't. When Ti0z sol, ZrO□ sol, etc. with such large particle sizes are used as additives for film forming agents, the resulting film has the disadvantage of poor uniformity and reduced transparency to visible light. This makes it unsuitable for use in this field of application. Therefore, especially as an additive for film-forming agents,
At present, it is not possible to obtain an organosol that has both the characteristics of ultraviolet absorption of 300 nm or less and the characteristics of a fine particle size.

On the other hand, organosols are also used as fillers in hard coating agents for high refractive plastic lenses (refractive index (n, ) of approximately 1.55 or higher), but the conditions for organosols suitable for this field of use are: The particle size of the sol particles is small, and (1) the refractive index of the sol particles is high. If the particle size is large, the transparency of the coating film will be lost, and if the refractive index of the particles is lower than that of the target lens base material, interference fringes will occur. For these conditions, organosilica sol has a particle refractive index of approximately 1.4 to 1.5.
As a result, it was unsuitable as a filler for high refractive index hard coating agents.

In addition, other organosols other than organosilica sol, such as 5bzOs sol and TiO□ sol, are known for their high particle refractive index. When used as a filler, a problem arises in that the transparency of the hard coat film becomes insufficient. Therefore, at present, an organosol that satisfactorily satisfies the above two conditions has not yet been obtained.

The present invention was developed in view of the above circumstances, and has excellent ultraviolet absorption ability of 300 nm or less, a fine sol particle size (low turbidity, excellent transparency to visible light, and a refractive index of sol particles). It is an object of the present invention to provide an organosol that can increase the yield and a method for producing the organosol.

[Means and effects for solving the problem] As a result of intensive studies to achieve the above object, the inventor has developed the following formula (2
) % Formula % (2) (However, R1 is an alkyl group having 1 to 4 carbon atoms.) Partial hydrolyzate of silicon alkoxide and the following formula (3) Ti(OR'')a...
(3) (However, R2 is an alkyl group having 1 to 4 carbon atoms.) By subjecting a partially clamped product with titanium alkoxide to a hydrolysis/polycondensation reaction in an organic solvent in the presence of an acid catalyst, It has been found that an organotitania-silica sol can be obtained which has the characteristics of low turbidity, ultraviolet blocking function, and the ability to increase the refractive index of sol particles.

That is, in the organotitania-silica sol obtained by the above method, the particle size of the titania-silica sol particles is usually 5 to 5.
The sol has a fine particle size of 50 nm and a low turbidity. Specifically, the turbidity (τ) of a sol with a concentration of 10% by weight of titania-silica fine particles is measured by spectrophotometry using a cell with an optical path length of 10+n and water as a reference. When calculated from the absorbance at a wavelength of 430 nm (A> measured by a meter using the following formula (1) % formula % (1), the turbidity is low at 5 cm-' or less, and the transparency to visible light is good. , found that the ultraviolet absorption edge is 300 nm or more and the ultraviolet absorption ability is excellent below 300 nm.In this case, by varying the ratio of silicon alkoxide and titanium alkoxide over a wide range, the refractive index of the sol particles can be adjusted to approx. It was found that the organotitania-silica sol obtained by the above method can be adjusted arbitrarily in the range of 1.4 to about 2. Therefore, the organotitania-silica sol obtained by the above method can be mixed with various film-forming agent additives, especially hard plastic sol of high refractive index. It has been discovered that it can be suitably used as a filler in coating agents, and the present invention has been completed.

Therefore, the present invention provides an organotitania-silica sol in which titania-silica fine particles are dispersed in an organic solvent, and (a) the turbidity (τ) of the sol with a concentration of titania-silica fine particles of 10% by weight is such that the optical path length is 10 m. When calculated using the following formula (1) from the absorbance (A) at a wavelength of 430 nm measured by a spectrophotometer using water as a reference using a cell of (b)
An organotitania-silica sol characterized by an ultraviolet absorption edge of 300 nm or more, and represented by the following formula (2) % formula % (2) (wherein R1 is an alkyl group having 1 to 4 carbon atoms) A partially clamped product of a silicon alkoxide partial hydrolyzate and a titanium alkoxide represented by the following formula (3) (where R2 is an alkyl group having 1 to 4 carbon atoms) is prepared in an organic solvent. Provided is a method for producing an organotitania-silica sol, which comprises performing a hydrolysis/polycondensation reaction in the presence of an acid catalyst to obtain the organotitania-silica sol.

Note that in this specification, the ultraviolet absorption edge refers to a wavelength at which the transmittance is 0% according to the ultraviolet absorption edge measurement method described below.

The present invention will be explained in more detail below.

The organotitania-silica sol of the present invention is produced using silicon alkoxide and titanium alkoxide as raw materials.

Here, as the silicon alkoxide, one represented by the following formula (2) (where R1 is an alkyl group having 1 to 4 carbon atoms) is used. Specifically, Si (OCH3
) a, 5i(OCJs)n, Si[0CR(C)b
)z14.5i(OCHzCHzCHs)4.5i(O
CHzCHzCHzCHs) a, Si[0CHzCH(
CHs)z]4, Si[0C(CH:+)3]4, etc., and one of these can be used alone or two or more of them can be used in combination. Further, as the titanium alkoxide, one represented by the following formula (3) (where R2 is an alkyl group having 1 to 4 carbon atoms) is used. Specifically, Ti (OCH3
) a, Ti (OCJs) 4, Ti [OCH(
CH:+) t] a, Ti (OCHzCHzCHs)
4. Ti(OCHzCHzCHzCHs)
HtCHCCH3)t)a, Ti[0C(CHsh]
4, etc., and one type of these can be used alone or two or more types can be used in combination. Note that the alkyl groups of silicon alkoxide and titanium alkoxide may be the same or different.

In addition, the usage ratio of titanium alkoxide and silicon alkoxide is determined by the Ti(
It can be selected depending on h/SiO□, and is preferably used so that the molar ratio of titanium alkoxide/silicon alkoxide is in the range of 0501 to 4, although it is not particularly limited. By setting the molar ratio of titanium alkoxide/silicon alkoxide in the range of 0.01 to 4 in this way, the T of the titania-silica sol particles obtained is
The molar ratio of i(h/5jOz can be adjusted in the range of 0.01 to 4, thereby making it possible to arbitrarily adjust the refractive index of the titania-silica sol particles in the range of about 1.4 to about 2. Therefore, when used as a filler in a hard coating agent for transparent plastics, glass, lenses, etc., the refractive index can be set appropriately depending on the refractive index of the base material.In addition, titanium alkoxide/silicon alkoxide If the molar ratio is less than 0.01, a sol with low turbidity may be obtained, but it may not be possible to obtain a sol with an ultraviolet absorption edge of 300 nm or more.On the other hand, if the molar ratio is greater than 4, the ultraviolet absorption edge may be Although it is possible to obtain a sol with a diameter of 300 nm or more, the particle size of the titania-silica sol particles becomes large and a sol with low turbidity may not be obtained. is the sol turbidity τ(
ell-') and the particle size of the sol particles is D (cm), the following equation holds true.

Therefore, from this equation, it is recognized that in order to obtain a sol with low turbidity, it is necessary to make the particle size of the sol particles as fine as possible.

The method for producing organotitania-silica sol of the present invention includes:
The above-mentioned partial hydrolyzate of silicon alkoxide is used and partially condensed with titanium alkoxide. However, the partial hydrolyzate of silicon alkoxide can be obtained by reacting silicon alkoxide with water in an organic solvent using an acid catalyst. can be obtained by

In this case, alcohol is preferably used as the solvent for the partial hydrolysis reaction of silicon alkoxide, and specifically, methanol, ethanol, isopropyl alcohol, n-propyl alcohol, isobutyl alcohol, 5ec-butyl alcohol, 'tert-butyl alcohol etc. are preferably used. Further, as the acid catalyst, mineral acids such as hydrochloric acid, nitric acid, and sulfuric acid, or organic acids such as acetic acid and oxalic acid are preferably used. Note that the water/silicon alkoxide molar ratio during partial hydrolysis is preferably 0.5 to 1.5. Further, the acid concentration is preferably in the range of 0.0001 to 0.1 mol/l based on the entire reaction system.

Through this partial hydrolysis process of silicon alkoxide,
A linear siloxane polymer represented by the following general formula % is produced.

By mixing the partial hydrolyzate of silicon alkoxide obtained in this way with titanium alkoxide,
A partial condensation reaction occurs, a titanosiloxane polymer is produced, and a partial condensate of a silicon alkoxide partial hydrolyzate and a titanium alkoxide can be obtained.

The organotitania-silica sol of the present invention can be obtained by subjecting this partial condensate to a hydrolysis/polycondensation reaction in an organic solvent in the presence of an acid catalyst.

Here, the @solvent is not particularly limited, but the alcohols exemplified in the above-mentioned partial hydrolysis reaction can be suitably used.

Furthermore, as for the type of acid catalyst, those exemplified in the above-mentioned partial hydrolysis reaction of silicon alkoxide can be suitably used, and the acid concentration can also be the same. In addition, throughout each reaction stage of partial hydrolysis of silicon alkoxide, partial IW combination of silicon alkoxide with titanium alkoxide, and hydrolysis/polycondensation of titanosiloxane polymer, the acid concentration is 0.0001 to 0.000% relative to the entire reaction system. 1 mol/l, especially 0.0
The amount is preferably in the range of 0.01 to 0.1 mol/l, thereby making it possible to obtain an organotitania-silica sol with low turbidity. If the acid concentration of the catalyst is less than o, oooi mol/l, the particles produced will become coarse and the desired sol with low turbidity may not be obtained. I! If the concentration is higher than that, it may take a long time to form sol particles.

Note that the rate of the hydrolysis/polycondensation reaction of the titanosiloxane polymer described above tends to be slower as the pH decreases. When carried out, it is thought that since the reaction proceeds in the presence of a large number of nuclei, titania-silica fine particles having a sufficiently small particle size are formed.

In the above hydrolysis/polycondensation reaction, the amount of water used, together with the amount of water used in the above-mentioned partial hydrolysis reaction, is determined by the ratio of HzO/(Si(OR')4+Ti(OR'')4) [ Hereinafter, HzO/M(OR) a ratio] is 2
-50, particularly preferably 4-20. If the HzO/M(OR) a ratio is less than 2, it may not be possible to completely hydrolyze the above titanosiloxane polymer, whereas 820/M
(OR), when the ratio is greater than 50, a large amount of water that is not consumed in the reaction remains, and in order to obtain the desired organoturu, a large amount of organic solvent is required in the subsequent solvent replacement step, which reduces efficiency. It can get worse.

In addition, in the reaction conditions during the hydrolysis and polycondensation reaction of this titanosiloxane polymer, the acid catalyst concentration and H2O
/ M (OR) By adjusting the two conditions of the 4 ratio, it is possible to arbitrarily control the particle size of the titania-silica particles. For example, by increasing the acid concentration, or by increasing the H
By lowering the zo/M (OR) a ratio,
The particle size of titania-silica particles can be made finer.

In addition, in the hydrolysis/polycondensation reaction of the above partial clamp, SiO□+T i O2Yl = 5% by weight or more,
In particular, it is preferable to carry out the reaction so that the amount is 65% by weight or more. If the reaction is carried out under conditions where the concentration is less than 5% by weight, the produced sol particles will not be sufficiently densified, so that the particle refractive index will not increase, and the stability of the produced sol may also be poor.

The organotitania-silica sol of the present invention obtained in this manner is an organosol in which titania-silica fine particles in which the two components TiO□ and Sing are uniformly mixed at the atomic level are dispersed in a solvent such as alcohol used during the reaction, Although it can be used as is, the obtained titania-silica fine particles have many unreacted alkoxy groups on the particle surface, and these unreacted alkoxy groups are gradually hydrolyzed over time. It promotes the association reaction between particles, and as a result, the stability of the resulting sol tends to be poor.

For this reason, the sol can be stabilized by adding an organosilicon compound to the organotitania-silica sol obtained as described above, or by replacing the alcohol in the dispersion medium of the sol with an alcohol having a larger number of carbon atoms. It is preferable to perform either or both of the treatments.

In this case, the reason why the sol is stabilized by adding an organosilicon compound is that the organosilicon compound modifies the surface of the titania-silica sol particles, inactivates the silanol groups or titanol groups on the surface of the particles, and deactivates the reactive moieties. It is thought that the sol is stabilized because it disappears and covers other alkoxy groups. Here, the type of the organosilicon compound mentioned above is not particularly limited, but includes, for example, alkoxysilanes such as trimethylmethoxysilane, trimethylethoxysilane, triethylmethoxysilane, and triethylethoxysilane, trimethylchlorosilane,
Examples include corosilanes such as triethylchlorosilane, silazane such as hexamethyldisilazane, or hexamethyldisiloxane, and these may be used alone or in combination of two or more to form titania-silica sol particles. It is preferably added in an amount of 5 to 200% by weight, particularly 20 to 100% by weight. In this case, these organosilicon compounds are represented by the following formula (4) (where R3, R4, and R5 are each an alkyl group having 1 to 4 carbon atoms). Modify the sol particles by changing.

Further, as a treatment method, the above-mentioned organosilicon compound may be simply added to the organotitania-silica sol and mixed.

On the other hand, the reason why the sol is stabilized by replacing the alcohol in the dispersion medium of the sol with an alcohol having a larger number of carbon atoms is because the following transesterification reaction occurs on the surface of the titania-silica sol particles. The alkoxy group OR3 with a larger number of carbon atoms is OR' or OR
As a result, the hydrolysis rate is slower than that of
It is thought that the association reaction between particles is suppressed.

Mi5i-OR'R'O)l Mi5i-O
R'MiTi-OR"MiTi-0
R'' (however, the number of carbon atoms in R3 > the number of carbon atoms in R', RZ) Here, the type of alcohol used for substitution is preferably one with a carbon number of 4 or more, such as an aliphatic saturated alcohol (
n-butyl alcohol, isobutyl alcohol, 5ec
-butyl alcohol, tert-butyl alcohol, n
- One type selected from the group consisting of amyl alcohol, isoamyl alcohol, hexyl alcohol, etc.), aliphatic unsaturated alcohols (allyl alcohol, etc.), aromatic alcohols (benzyl alcohol, etc.), alicyclic alcohols (cyclopentanol, etc.), or Two or more types can be used. As a means for solvent substitution, a conventionally known solvent substitution method can be employed, and can be easily carried out using, for example, a rotary evaporator.

If the sol concentration during synthesis of the titania-silica sol stabilized in this way is low, it can be concentrated to a practical concentration, usually 10 to 30% by weight, by using a rotary evaporator or the like. . The organotitania silica sol of the present invention has a sol concentration of 10 after concentration.
The stability is good even at a high concentration of ~30% by weight, and even at this high concentration, the sol generally has a low viscosity of 100 cp or less and is easy to handle.

The organotitania-silica sol of the present invention obtained in this way has a turbidity (τ) of the sol with a concentration of 10% by weight of titania-silica fine particles as measured by a spectrophotometer using a cell with an optical path length of 10 m and water as a reference. Measured wavelength 43
When calculated from the absorbance (A) at 0 nm using the following formula (1) % formula % (1), it is 5C1l-' or less, the ultraviolet absorption edge is 300 nm or more, and it has excellent transparency to visible light. It also has the characteristic of having excellent ability to absorb ultraviolet light of 300 nm or less. Therefore, it can be suitably used as an additive for various film forming agents, especially titania.
Since the refractive index of the silica sol particles can be arbitrarily adjusted within the range of about 1.4 to about 2, it can be suitably used as a filler for hard coating agents for transparent plastics, glass, lenses, etc., for example.

〔Effect of the invention〕

As explained above, the organotitania-silica sol of the present invention has a low turbidity and ultraviolet blocking function, and also has the characteristics of being able to increase the refractive index of titania-silica fine particles, and therefore absorbs ultraviolet rays. It is suitable as an additive for a film forming agent, and according to the method for producing an organotitania-silica sol of the present invention, such a novel organotitania-silica sol can be reliably and efficiently produced.

EXAMPLES Hereinafter, the present invention will be specifically explained by showing examples and comparative examples, but the present invention is not limited to the following examples. In addition, in the following examples, % is weight %.

[Example 1] 0.2N hydrochloric acid aqueous solution 14 in 11 four-bottle flasks
．． Ethyl orthosilicate (
166.7 g (0.80 mol) (manufactured by Tama Chemical) was added dropwise thereto, and the mixture was stirred at 20° C. for 1 hour. Titanium tetraisopropoxide (Wako Tsumugi Pharmaceutical Co., Ltd., - grade) was added to this solution.
4.6 g (0.58 mol) were added dropwise at 20°C. After the dropwise addition was completed, stirring was continued for 1 hour.

This solution was then placed in a 21-meter four-bottle flask at 35
60.1 g of 0.02N hydrochloric acid aqueous solution (3,
34 mol) and 823.4 g of ethanol over about 40 minutes, stirring was continued for an additional hour.
A titania-silica sol was prepared.

71.9 g of KBM-31 (manufactured by Shin-Etsu Chemical, trimethylmethoxysilane) was added dropwise to this titania-silica sol at room temperature, and the mixture was stirred with a magnetic stirrer for about 3 hours.
The surface of titania-silica particles was modified. The appearance of the obtained titania-silica sol was pale blue.

Next, the sol was concentrated using a rotary evaporator until the sol particle concentration was about 10%. The turbidity of this concentrated sol was measured using a spectrophotometer UV I DEO-660 (manufactured by JASCO) according to the method below.
1.23 m-', and the ultraviolet absorption edge was 354 nm from the transmission spectrum. The viscosity of the sol after concentration was 5.2 cp, and it was stable for more than half a year at room temperature.

Sol turbidity method The absorbance (A) at a wavelength of 430 nm of a sol prepared to a concentration of 10% is measured with a spectrophotometer using a cell with an optical path length of 10 m. In this case, water is used as a reference.

τ=AX2.303 The turbidity τ (am-') is calculated using the formula.

Measurement of Violet Color of Sol The transmittance spectrum of a sol prepared to a concentration of 10% is measured with a spectrophotometer using a cell with an optical path length of 10 mm. In this case, water is used as a reference. The wavelength at which the transmittance becomes 0% is defined as the ultraviolet absorption edge.

[Example 2] A titania-silica sol was prepared with the same composition as in Example 1.

Next, using a rotary evaporator, the dispersion medium of the sol was replaced from ethanol to n-butyl alcohol while the composition of the dispersion medium of the sol was confirmed by gas chromatography. The appearance of the obtained titania-silica sol was pale blue.

Next, it was concentrated until the sol particle concentration was about 10%. The turbidity of the sol after concentration was measured in the same manner as above, and it was 1.313-', and the refractive index of the sol particles was calculated, and it was 1.72.

The viscosity of the sol after concentration was 4.7 cp, and it was stable for more than half a year at room temperature.

Note that the refractive index of the sol particles was determined as follows.

n, = (n, -n,) X -+n.

Nicode, n: refractive index of sol particles nl: refractive index of sol no: refractive index of solvent d: density of particles (g/am”) C: sol particle concentration Cg/cs3) [Comparative Example 1] Commercially available methanol-dispersed silica sol (Sing concentration 31.
7%) with methanol to obtain a 10% methanol-dispersed silica sol. The turbidity and ultraviolet absorption edge of this diluted Solulu were measured in the same manner as in the above example. The turbidity of the sol was 0.34 cm-', but the ultraviolet absorption edge was 230 nm.
It was m.

[Comparative Example 2] Commercially available water-dispersed titania sol (TiO□ concentration 10.2%)
The turbidity and ultraviolet absorption edge of the sample were measured in the same manner as in the above example. The ultraviolet absorption edge was 380 nm, but the turbidity of the sol was 8.54 am-'.

[Comparison, Comparative Example 3] A commercially available water-dispersed titania sol (Ti-
The turbidity and ultraviolet absorption edge of the sample (Ox concentration 10.2%) were measured in the same manner. The ultraviolet absorption edge was 380 nm, and the turbidity of the sol was 5.52 C1l-'.

[Comparative Example 4] A titania silica sol was prepared with the same composition as in Example 1.

Next, without adding any organosilicon compound to this sol or replacing the dispersion medium of this sol, the sol was directly concentrated until the concentration of sol particles reached 10%.

This concentrated sol gelled after being left at room temperature for about one month.

[Comparative Example 5] A titania-silica sol was prepared with the same composition as in Example 1.

Next, without adding any organosilicon compound to this sol, the dispersion medium of this sol was replaced with n-propyl alcohol, and then the sol was concentrated until the concentration of sol particles was about 10%. During this solvent replacement and concentration operation, the turbidity of the sol increased to 7.20c.
It became sa-'. Moreover, the sol after this concentration is about 2
It gelled after being left for a month.

Claims (1)

[Claims] 1. An organotitania-silica sol in which titania-silica fine particles are dispersed in an organic solvent, wherein (a) the turbidity (τ) of the sol with a concentration of titania-silica fine particles of 10% by weight;
However, from the absorbance (A) at a wavelength of 430 nm measured by a spectrophotometer using a cell with an optical path length of 10 mm and water as a reference, it is calculated by the following formula (1) τ = A × 2.303 (1) An organotitania-silica sol characterized in that it is 5 cm^-^1 or less when calculated, and (b) has an ultraviolet absorption edge of 300 nm or more. 2. The following formula (2) Si(OR^1)_4...(2) (However, R^1 is an alkyl group having 1 to 4 carbon atoms.)
A partial hydrolyzate of silicon alkoxide represented by the following formula (3) Ti(OR^2)_4...(3) (However, R^2 is an alkyl group having 1 to 4 carbon atoms.)
An organotitania-silica sol according to claim 1, which is obtained by subjecting a partial condensate with a titanium alkoxide represented by the above to a hydrolysis/polycondensation reaction in an organic solvent in the presence of an acid catalyst. Production method. 3. Production of the organotitania-silica sol according to claim 2, wherein the surface of the titania-silica fine particles is modified by reacting the titania-silica fine particles obtained by hydrolysis/polycondensation reaction with an organosilicon compound. Method. 4. The organic solvent in which the titania-silica fine particles obtained by the hydrolysis/polycondensation reaction are dispersed is replaced with a different alcohol having 4 or more carbon atoms, and the titania-silica fine particles are dispersed in the alcohol. 3. The method for producing an organotitania-silica sol according to claim 2.