JPH08269359A - Hydrophobic metatitanic acid fine particle and its production - Google Patents

Abstract

PURPOSE: To obtain the subject fine particles having specified physical properties, excellent in dispersibility, useful for coating materials, etc., by deflocculating metatitanic acid followed by treatment with a specified amount of an alkoxysilane, and then neutralized, filtrated, washed, and dried at specified temperatures. CONSTITUTION: Metatitanic acid synthesized by the hydrolysis involved in sulfuric acid method is deflocculated, and treated with 10-100wt.%, based on the metatitanic acid, of an alkoxysilane of the formula RnSiR'm (R is a hydrocarbon; R' is an alkoxy; (n) and (m) are each 1-3; (n+m)=4); the resultant metatitanic acid is neutralized with an alkali, followed by filtration and washing, and then dried at 100-190 deg.C, thus obtaining the objective hydrophobic metatitanic acid fine particles 0.01-0.1Lμm in diameter, 100-300m<2> /g in specific surface area, 20-70% in hydrophobicization degree and >=70% in the light transmittance at a wavelength of 550nm.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention has an excellent hydrophobicity and dispersibility, and an ultraviolet absorber such as paint, plastic and fiber.
The present invention relates to fine particles of metatitanic acid used as a charge control agent and a fluidizing agent for electrophotographic toner.

[0002]

2. Description of the Related Art Ultrafine particles of titanium oxide are used in cosmetics, paints, inks, plastics, etc. for the purpose of blocking ultraviolet rays, and are also widely used as a charge control agent and a fluidizing agent for electrophotographic toners. . In these applications, titanium oxide whose surface is hydrophobized is used to improve dispersibility and prevent hygroscopicity.

Conventionally, as the base fine particles, titanium oxide synthesized by vapor phase oxidation of titanium tetrachloride or titanium alkoxide and titanium oxide dehydrated and baked by the sulfuric acid method have been used. (Kaihei 1-153529) or in an aqueous solution (JP-A-5-19528 and JP-A-2-216440), the treatment with a silane coupling agent was carried out, but metatitanic acid was to be coated. There was no. Further, titanium oxide synthesized by vapor-phase oxidation of titanium alkoxide treated with a silane coupling agent has a high degree of hydrophobicity, a high specific surface area, and good dispersibility, but is expensive. On the other hand, titanium oxide synthesized by vapor-phase oxidation of titanium tetrachloride or titanium oxide dehydrated and baked by the sulfuric acid method and treated with a silane coupling agent can be produced relatively inexpensively, but has a small specific surface area, The dispersibility was also poor.

[0004]

DISCLOSURE OF THE INVENTION An object of the present invention is to provide fine particles having a high degree of hydrophobicity and a high specific surface area and good dispersibility relatively easily and at low cost.
It was an object to produce fine particles having high specific surface area and good dispersibility without using expensive titanium alkoxide, and having a higher specific surface area than conventional titanium oxide obtained by a vapor phase method or a sulfuric acid method of titanium tetrachloride. .

[0005]

The present inventors have completed the present invention as a result of intensive research to develop fine particles having a hydrophobicity, a specific surface area and good dispersibility. .

That is, the present invention is characterized in that a non-aggregating slurry obtained by deflocculating hydrochloric acid of metatitanic acid synthesized by a sulfuric acid method hydrolysis reaction is treated with an alkoxysilane in an aqueous system to obtain a hydrophobic metatitanic acid. It provides fine particles.

The hydrophobic metatitanic acid fine particles according to the present invention are coated with metatitanic acid as a base material in an amount of 10 to 100% by weight as an alkoxysilane to form 100 to 190.
Obtained by drying at ° C.

The metatitanic acid, which is the base material of the present invention, is obtained by a hydrolysis reaction by the sulfuric acid method and may have a primary particle size of 0.01 to 0.1 μm as determined by an electron micrograph.

Next, the process of completing the hydrophobic metatitanic acid fine particles according to the present invention will be described.

In order to obtain the hydrophobic fine particles, a method of treating the alkoxysilane with a water system was investigated by pulverizing and dispersing powder obtained by drying and firing metatitanic acid to obtain monodispersion. In this method, particularly, When the particle size of metatitanic acid became fine, strong aggregation occurred during drying and firing of metatitanic acid. Therefore, the degree of hydrophobicity could be increased, but the specific surface area was small and the dispersibility was poor, which was not much different from the conventional ultrafine particle titanium oxide.
Therefore, as a result of continuing studies to solve this problem,
Powder obtained by solid-liquid separation and decomposing of metatitanic acid by hydrochloric acid deflocculation, and by adding coating with alkoxysilane in the state of non-aggregating slurry, even though it is metatitanic acid which is a water-containing substance. Has a high degree of hydrophobicity,
Moreover, it was found that the fine particles have a high specific surface area and maintain the non-aggregation property even after drying, and thus the present invention has been completed.

The detailed description of the manufacturing method of the present invention will be continued.

The lower limit of the particle size range of metatitanic acid as a raw material is preferably 0.01 μm, more preferably 0.1.
If it is too small, coagulation cannot be sufficiently suppressed even if the alkoxysilane is treated. On the other hand, the upper limit of the particle size is preferably 0.07 μm, more preferably 0.0
5 μm. This is because if it is too large, the peptization speed becomes very slow and it is not practical.

There are several methods for peptization treatment of metatitanic acid. For example, adding ammonia or caustic to the slurry of agglomerated metatitanic acid, neutralizing, filtering,
Washing with water to remove the remaining sulfate radicals, followed by hydrochloric acid,
There is a method in which a strongly basic monobasic acid such as nitric acid or trichloroacetic acid is added to adjust the pH to 3 or less, preferably 0.9 to 2.0. In addition, a method of adding a salt that reacts with a sulfate group to form an insoluble sulfate salt and at the same time forms a monobasic acid, for example, barium chloride, without treating the desulfated root, There is. The former method, in particular the method of peptizing using hydrochloric acid, is more suitable in order to make the state in which the alkoxysilane is dissolved and easily reacted without mixing of foreign substances.

When the alkoxysilane is added, the pH is preferably 3.0 or less, more preferably pH 2.0 or less. Re-aggregation of metatitanic acid can be further successfully prevented by adjusting the pH to the above value or less. Also,
When adding alkoxysilane, preferably pH
Perform at 0.9 or higher. By setting the pH to the above value or more, the coating treatment of the alkoxysilane can be uniformly promoted.
Also, after the stirring and holding, for the purpose of promoting the hydrolysis reaction,
Neutralization is performed using an alkali so that the pH is preferably 4-9, more preferably 5-7. The temperature of the reaction slurry is preferably heated to 20 to 100 ° C, more preferably 30 to 70 ° C.

The alkoxysilane has the general formula
RnSiR'm R: a hydrocarbon group including an alkyl group, a phenyl group, a vinyl group, a glydoxy group, a mercapto group, and a methacryl group n: an integer of 1 to 3 R ': an alkoxy group m: an integer of 1 to 3 n + m = 4 For example, vinyltrimethoxysilane, propyltrimethoxysilane, i-butyltrimethoxysilane, n-butyltrimethoxysilane, n-hexyltrimethoxysilane, n-octyltrimethoxysilane, n-dodecyl. Examples thereof include triethoxysilane, phenyltrimethoxysilane, and 3-glydoxypropyltrimethoxysilane, and the hydrocarbon group R preferably has 2 to 10 carbon atoms. When the number of carbon atoms is 1, the degree of hydrophobicity is low because the molecular chain length is short, and the particles are not sufficiently separated from each other during drying, so that aggregation occurs and the dispersibility decreases.
On the other hand, those having 11 or more carbon atoms are not preferable because the molecular chain length is too long and the molecular chains are entangled to cause aggregation, and the specific surface area is decreased. Further, an emulsion of silicone oil such as polydimethylsiloxane or a titanate coupling agent is effective for increasing the hydrophobicity, but it is not preferable for the same reason because the molecular chain is long.

The coating amount of alkoxysilane is 10 to 100% by weight with respect to the metatitanic acid of the substrate, preferably 20.
-80%, more preferably 25-50%. If it is too small, the degree of hydrophobicity will be low, and if it is too large, aggregation will occur and the specific surface area will also be reduced. The alkoxysilanes may be used in combination of two or more.

The alkali used for neutralization is, for example,
Sodium hydroxide, potassium hydroxide, sodium carbonate,
Potassium carbonate, ammonium carbonate, aqueous ammonia, ammonia gas and the like can be used.

The drying temperature after washing with water is 100 ° C to 190 ° C,
It is preferably 110 ° C to 170 ° C. If it is too low, the drying efficiency is poor and the hydrophobicity is low. If it is too high, thermal decomposition of hydrocarbon groups will occur, causing discoloration and a decrease in hydrophobicity.

[0019]

The present invention will be described in more detail with reference to the following examples. The following examples are provided for illustration only and the scope of the invention is not limited thereby.

Example 1 A 4N sodium hydroxide aqueous solution was added to a metatitanic acid slurry having a particle size of 0.03 μm with stirring to adjust the pH to 9.0, and the mixture was stirred and held for 1 hour, and then neutralized to pH 5.5 with 6N hydrochloric acid. , Filtered and washed with water. Water was added to the washed cake to make a slurry again, and while stirring, 6N hydrochloric acid was added to adjust the pH to 1.2, and the mixture was stirred and held for 2 hours for deflocculation treatment. From this deflocculated slurry, 100 g of metatitanic acid was taken out, and 40 g (40% by weight) of ethyltrimethoxysilane was added while stirring while heating at 35 ° C.
Was added, and the mixture was stirred and held for 30 minutes, 8N aqueous sodium hydroxide solution was added to neutralize the solution to pH 6.5, and the mixture was filtered and washed with water.

The cake filtered and washed with water was dried at 150 ° C. and then pulverized with an air jet type pulverizer to obtain the desired fine particles of hydrophobic metatitanic acid.

Example 2 The same procedure as in Example 1 was carried out except that ethyltrimethoxysilane was changed to n-propyltrimethoxysilane to obtain the desired hydrophobic metatitanic acid fine particles. It was

Example 3 The same procedure as in Example 1 was performed except that ethyltrimethoxysilane was changed to n-butyltrimethoxysilane and the drying temperature was changed from 150 ° C. to 170 ° C. The hydrophobic metatitanic acid fine particles having

Example 4 The same procedure as in Example 1 was repeated except that ethyltrimethoxysilane was changed to i-butyltrimethoxysilane and the drying temperature was changed from 170 ° C. to 170 ° C. The hydrophobic metatitanic acid fine particles having

Example 5 The target hydrophobic metatitanic acid fine particles were obtained by the same procedure as in Example 1 except that n-hexyltrimethoxysilane was used instead of ethyltrimethoxysilane in Example 1. It was

Example 6 The same treatment as in Example 1 was carried out except that 40 g of ethyltrimethoxysilane was changed to 30 g (30% by weight) of n-decyltrimethoxysilane in Example 1 to obtain the object. Hydrophobic metatitanic acid fine particles were obtained.

Example 7 In Example 1, 40 g of ethyltrimethoxysilane was changed to 50 g (50% by weight) of n-butyltrimethoxysilane and a drying temperature of 150 ° C. was adjusted to 1
The same treatment as in the case of the same example except that the temperature was 70 ° C. was carried out to obtain the desired fine particles of hydrophobic metatitanic acid.

[Embodiment 8] In Embodiment 1, in place of metatitanic acid having a particle diameter of 0.03 μm, a particle diameter of 0.02 is used.
In addition to using 40 .mu.m of ethyltrimethoxysilane and 40 g (40% by weight) of n-butyltrimethoxysilane as the drying temperature of 150.degree.
The same treatment as in the case of the same example was carried out to obtain the target fine particles of hydrophobic metatitanic acid.

Example 9 In Example 1, the particle size was 0.02 instead of metatitanic acid having a particle size of 0.03 μm.
μm metatitanic acid was used, ethyltrimethoxysilane was changed to i-butyltrimethoxysilane, and the drying temperature was 150.
Except that the temperature was 170 ° C., the same treatment as in the case of the same example was carried out to obtain the desired fine particles of hydrophobic metatitanic acid.

[Embodiment 10] In Embodiment 1, instead of metatitanic acid having a particle diameter of 0.03 μm, a particle diameter of 0.0
Using 4 μm metatitanic acid, ethyltrimethoxysilane was changed to n-butyltrimethoxysilane, and the drying temperature was 15
Except that 0 ° C. was changed to 170 ° C., the same treatment as in the case of the same example was carried out to obtain the objective fine particles of hydrophobic metatitanic acid.

[Embodiment 11] In Embodiment 1, instead of metatitanic acid having a particle diameter of 0.03 μm, the particle diameter is 0.0
Using 4 μm of metatitanic acid, 40 g of ethyltrimethoxysilane and 30 g (30 g of n-butyltrimethoxysilane) were used.
% By weight) and the drying temperature was changed from 150 ° C. to 170 ° C., and the same treatment as in the same example was carried out to obtain the desired hydrophobic metatitanic acid fine particles.

[Embodiment 12] In Embodiment 1, a particle size of 0.03 μm is used instead of the metatitanic acid having a particle size of 0.03 μm.
Using 5 μm of metatitanic acid, 40 g of ethyltrimethoxysilane and 30 g (30 g of n-butyltrimethoxysilane) were used.
% By weight) and the drying temperature was changed from 150 ° C. to 170 ° C., and the same treatment as in the same example was carried out to obtain the desired hydrophobic metatitanic acid fine particles.

[Example 13] In Example 1, the particle size was 0.03 μm instead of 0.03 μm.
Using 7 μm of metatitanic acid, 40 g of ethyltrimethoxysilane and 20 g of n-butyltrimethoxysilane (20 g
% By weight) and the drying temperature was changed from 150 ° C. to 170 ° C., and the same treatment as in the same example was carried out to obtain the desired hydrophobic metatitanic acid fine particles.

Example 14 The same procedure as in Example 3 was carried out except that the drying temperature was changed from 150 ° C. to 110 ° C. to obtain the desired hydrophobic metatitanic acid fine particles.

Comparative Example 1 The particle size of Example 1 is 0.03.
A 4N aqueous sodium hydroxide solution was added to the μm metatitanic acid deflocculating slurry to adjust the pH to 6.0, followed by filtration and washing with water.
The hydrophilic titanium dioxide powder obtained by drying at 110 ° C. and heating at 300 ° C. for dehydration was rehydrated and finely pulverized into a slurry using a wet ball mill. Subsequently, a slurry of 100 g of TiO ₂ was taken out of the solution, and 6N hydrochloric acid was added thereto with stirring to adjust the pH to 1.2. Next, while maintaining the temperature at 35 ° C. and adding 25 g of n-butyltrimethoxysilane while stirring, and stirring and holding for 30 minutes, 8N aqueous sodium hydroxide solution was added to neutralize to pH 6.5, and filtration and washing with water were performed. It was

The cake filtered and washed with water was dried at 170 ° C. and then pulverized by an air jet pulverizer to obtain hydrophobic titanium oxide fine particles.

Comparative Example 2 The particle size of Example 14 is 0.0
Using 5 μm of metatitanic acid, the same treatment as in Comparative Example 1 was carried out to obtain hydrophobic titanium oxide fine particles.

Comparative Example 3 The particle size of Example 1 was 0.03.
μm metatitanic acid, pH with aqueous sodium hydroxide
Without desulfurization treatment to 9.0, 6N hydrochloric acid was added as it was to adjust the pH to 1.2 and the mixture was maintained for 2 hours.

Since sulphate radicals remained in this metatitanic acid slurry, peptization did not occur. In Example 1,
An unpeptized slurry was used in place of the peptized slurry, and ethyltrimethoxysilane was replaced with n-butyltrimethoxysilane,
Hydrophobic metatitanic acid fine particles were obtained by the same treatment as in the same example except that the drying temperature was changed from 150 ° C to 170 ° C. [Comparative Example 4] Hydrophobic metatitanium was prepared in the same manner as in Example 1 except that methyltrimethoxysilane (having 2 carbon atoms in R) was changed to methyltrimethoxysilane (having 1 carbon atom) in Example 1. Acid fine particles were obtained.

[Comparative Example 5] In Example 1, except that 40% by weight of ethyltrimethoxysilane was 25% by weight as an active ingredient of polydimethylsiloxane emulsion (SM-7060 manufactured by Toray Dow Corning Silicone Co., Ltd.). Then, the same treatment as in the case of the same example was carried out to obtain hydrophobic metatitanic acid fine particles.

Table 1 shows the measurement results of the samples obtained in Examples 1 to 14 and Comparative Examples 1 to 5. These measured values are values measured in the following manner.

(1) Specific surface area Using an area meter manufactured by Strerain, Germany,
It was measured by the BET method.

(2) Hydrophobicity: An aqueous solution containing 2.5% by weight of methanol was prepared in a test tube, and a small amount of fine powder was added to confirm the presence or absence of sedimentation. The degree of hydrophobicity is as follows: No sedimentation weight% to sedimentation weight%
Was expressed as the degree of hydrophobicity (%).

(3) Dispersibility 40 ml of methanol and about 10 mg of fine particles were collected in a 50 ml glass beaker and dispersed for 5 minutes using an ultrasonic cleaner B1200J1 manufactured by Nippon Emerson Co., Ltd.

The dispersion is Ubest5 manufactured by JASCO Corporation.
0 was used to measure the value at 550 nm of a liquid diluted and adjusted with methanol so that the transmittance at 300 nm was 17.5%. The transparent one having a high value of 550 nm had less large particles and was judged to have good dispersibility.

[0046]

[Table 1] * 1) Metatitanic acid converted to titanium dioxide by heating at 300 ° C.

* 2) A cohesive metatitanic acid which has not been deflocculated.

[0048]

INDUSTRIAL APPLICABILITY The present invention relatively easily and inexpensively produces fine particles having high hydrophobicity and specific surface area and excellent dispersibility which can be used in various fields, and has industrially high advantages. .

Claims (4)

[Claims] 1. A metatitanic acid which is a substrate is coated with 10 to 100% by weight of alkoxysilane, and has a particle size of 0.01 to 0.1 μm and a specific surface area of 100 to 30.
Hydrophobic metatitanic acid fine particles having a particle size of 0 m ² / g. 2. The alkoxysilane used is of the general formula R
nSiR'm (R: hydrocarbon group, R ': alkoxy group, n
= 1-3, m = 1-3, n + m = 4), The hydrophobic metatitanic acid fine particles according to claim 1. 3. The degree of hydrophobicity is 20 to 70%, and
The hydrophobic metatitanic acid fine particles according to claim 1 or 2, wherein the transmittance at 550 nm is 70% or more. 4. A peptization treatment of metatitanic acid synthesized by a hydrolysis reaction with a sulfuric acid method, a treatment of 10 to 100% by weight of alkoxysilane with respect to a metatitanic acid as a substrate, neutralization with an alkali, filtration, After washing, 100-190
The method for producing fine particles of hydrophobic metatitanic acid according to any one of claims 1 to 3, wherein the method is performed at a temperature of ℃.