JPH07215709A - Production of titanium phosphate amorphous particle - Google Patents

Abstract

PURPOSE:To obtain a producing method capable of improving the yield and controlling the particle diameter of a formed particle by mixing a titanium alkoxide solution having specific concn. with a phosphorous compound solution while specifying mol ratio thereof and allowing them to react with each other. CONSTITUTION:The solution (A) having 0.1-2.0mol/l titanium alkoxide and 0.1-0.5mol/l multiple element alkoxide is prepared by combining one or more kind of the titanium alkoxide expressed by a formula, Ti(OR)4 (R is 1-5C alkyl), or at least one of Zr element or Al element as composite element components and dissolving in a 1-5C alcohol. The phosphorous compound (B) is obtained by dissolving at least one kind of phosphoric acid, methyl phosphate or potassium dihydrogen phosphate in the 1-5C alcohol to form 0.01-5.6mol/l alcoholic solution and adding 1.0-50mol/l water thereinto. The ratio of the molar number (P) of component (B) to the molar number (Me) of component (A) is controlled to <=4 and one of the components is dropped in the other component while stirring at the rate of 0.1-1001/min to control the particle diameter to prescribed size.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing titanium phosphate amorphous particles, and more particularly to a method for producing titanium phosphate amorphous particles which has a high reaction yield and can control the particle size of the produced particles.

[0002]

BACKGROUND OF THE INVENTION In addition to ion exchange materials, metal phosphates are used not only as ion-exchange materials, but also as surface conditioning agents for metal surface treatments, rust preventive pigments, etc., and also ion conductors and ferroelectrics. It is also used in electronic materials such as bodies and phosphors. The metal phosphate is usually synthesized by reacting a phosphorus compound such as phosphoric acid or a phosphoric acid ester with a metal salt or a metal alkoxide.

Various methods for synthesizing metal phosphates have been proposed. For example, a solution obtained by dissolving a metal alkoxide in an organic solvent that has a lower density than water such as toluene and benzene and is immiscible with water, and a phosphoric acid aqueous solution are put in a reaction tank, and a solution between the metal alkoxide solution and the phosphoric acid aqueous solution is A method for producing amorphous metal phosphate particles having a particle size of 20 nm or less by stirring the interface has been proposed (JP-A-63)
-115773). However, the titanium compound was not included. Also, Benhamza et al. Reported that a zirconium phosphate synthesis reaction proceeded faster using zirconium alkoxide than zirconium oxychloride (J. Mater. Chem., 1 (4), 681).
-684 (1991)).

On the other hand, Schmutz et al. Reported a method for synthesizing a thin film of potassium titanium phosphate (J. Mater. Chem., 3 (4), 393-397 (1993)). Schmutz et al. Synthesize colloidal potassium potassium phosphate by adjusting the POH / Ti ratio and the H ₂ O / Ti ratio,
A thin film of potassium titanium phosphate is produced by coating the object.

However, a method for producing titanium phosphate particles has not been proposed yet. In addition, JP-A-63-
The method for producing metal phosphate particles disclosed in No. 115773 has a drawback that the diameter of the obtained particles cannot be controlled,
The yield of the reaction is not sufficient.

Therefore, an object of the present invention is to provide a method for producing titanium phosphate amorphous particles which has a high yield and can control the particle size of the particles produced.

[0007]

As a result of earnest research in view of the above problems, the present inventor found that titanium phosphate amorphous particles were obtained by adding and mixing a specific concentration of titanium alkoxide and a specific concentration of a phosphorus compound at a constant rate. The present invention was completed by discovering that the particle size of the obtained particles can be controlled by synthesizing the compound in addition to high yield.

That is, the first method of the present invention for producing amorphous titanium phosphate particles involves mixing a titanium alkoxide and a phosphorus compound and hydrolyzing them to carry out a polycondensation reaction. The general formula Ti (OR) ₄ (wherein R is an alkyl group having 1 to 5 carbon atoms), at least one or more of the titanium alkoxides described above are dissolved in alcohol to prepare a solution having a concentration of 0.1 to 2.0 mol / liter. The phosphorus compound is dissolved in alcohol to prepare a solution having a concentration of 0.01 to 5.6 mol / liter, and the ratio of the number of moles of the phosphorus compound (P) to the number of moles of the titanium alkoxide (Me) ( It is characterized in that the titanium alkoxide solution and the phosphorus compound solution are mixed and reacted so that P / Me) becomes 4.0 or less.

The present invention will be described in detail below. (a) Titanium alkoxide alcohol solution In the present invention, a titanium alkoxide represented by the general formula Ti (OR) ₄ (wherein R is an alkyl group having 1 to 5 carbon atoms) is used. R is a linear alkyl group or a branched alkyl group. Preferred R is an alkyl group having 1 to 3 carbon atoms. Examples of titanium alkoxides having such an alkyl group include Ti (OCH ₃ ) ₄ and Ti (OC ₂ H
_{5) 4, Ti (O-} n-C 3 H 7) 4, Ti (O-i-
_{C 3 H 7) 4, Ti} (O-n-C 4 H 9) 4, Ti (O
_{-I-C 4 H 9) 4} , Ti (O-t-C 4 H 9) 4 , and the like. These titanium alkoxides can be used alone or in combination of two or more.

Further, at least one of zirconium element and aluminum element can be used in combination as a composite element component. By adding the composite element component, the titanium phosphate particles produced can have higher anticorrosion performance.

As a solvent for dissolving the above titanium alkoxide compound or mixture, an alcohol having 1 to 5 carbon atoms is used, and the carbon chain of the alcohol may be linear or branched. Such alcohols include methanol, ethanol, isopropyl alcohol, butanol and t
-Butyl alcohol and the like.

In a titanium alkoxide solution prepared by dissolving a titanium alkoxide compound in alcohol,
The concentration of titanium alkoxide is 0.1 to 2.0 mol / liter. When the titanium alkoxide concentration is less than 0.1 mol / liter, titanium phosphate particles cannot be obtained, and when the titanium alkoxide concentration exceeds 2.0 mol / liter, titanium phosphate is gelled and particles having a desired size are obtained. May not be obtained. The preferred titanium alkoxide concentration is 0.2 to 1.0 mol / liter.

When a mixture of titanium alkoxide and complex element alkoxide is used, the concentration of titanium alkoxide is 0.05 to 1.0 mol / liter, and the concentration of complex element alkoxide is 0.05 to 1.0 mol. / L, and preferably the concentration of titanium alkoxide is 0.
The concentration of the alkoxide of the composite element is 1 to 0.5 mol / liter, and the concentration is 0.1 to 0.5 mol / liter. As a result, the molar ratio of the composite element to titanium in the obtained titanium phosphate amorphous particles becomes 0.5 to 2.0, preferably 0.8 to 1.0.

(B) Alcohol Solution of Phosphorus Compound In the present invention, phosphoric acid (orthophosphoric acid), phosphorous acid, diphosphorous acid, metaphosphoric acid, pyrophosphoric acid and alkaline salts (for example, potassium salt) of these acids are used as phosphorus compounds. , Sodium salt, etc.) and phosphoric acid ester etc. can be used alone or in combination. Examples of the phosphate ester include alkyl phosphates such as methyl phosphate, dimethyl phosphate, ethyl phosphate, and diethyl phosphate. The alkyl group in the alkyl phosphate preferably has 1 to 4 carbon atoms. Particularly, it is preferable to use at least one kind of phosphoric acid, methyl phosphate, ethyl phosphate or potassium dihydrogen phosphate.

The above phosphorus compound is soluble in an alcohol having 1 to 5 carbon atoms. As in the case of titanium alkoxide, the carbon chain in the alcohol may be linear or branched, such as methanol, ethanol, isopropyl alcohol,
Butanol, t-butyl alcohol, etc. are mentioned. The solvent for the phosphorus compound may be different from the above-mentioned solvent for the titanium alkoxide, but it is preferable to use the same solvent as the titanium alkoxide.

The concentration of the phosphorus compound in the alcohol solution is 0.01 to 5.6 mol / liter. When the phosphorus compound concentration is less than 0.01 mol / liter, titanium phosphate particles cannot be obtained, and the phosphorus compound concentration is 5.6 mol / liter.
If it exceeds liter, titanium phosphate may be gelated and particles having a desired size may not be obtained. A preferable phosphorus compound concentration is 0.15 to 4.0 mol / liter.

Water is added to the phosphorus compound solution, preferably distilled water or ion-exchanged water. Water is used for the hydrolysis of titanium alkoxide. The concentration of water is 1.0 to 50 mol / liter. If the concentration of water exceeds 50 mol / liter, titanium phosphate will gel. Further, if the concentration of water is less than 1.0 mol / liter, the yield becomes extremely poor, which is not preferable.

(C) Synthesis Method (1) Addition and Mixing One of the alcoholic solutions of the titanium alkoxide and the phosphorus compound is added and mixed to the other at a predetermined rate while stirring. The titanium alkoxide solution may be added dropwise to the stirring phosphorus compound solution, or the phosphorus compound solution may be added dropwise to the stirring titanium alkoxide solution.

Total number of moles of phosphorus compound used in reaction (P)
To the total number of moles of titanium alkoxide (Me) (P / M
e) is 4 or less. If the P / Me ratio exceeds 4, the yield of the synthetic reaction will drop sharply. A preferable P / Me ratio is 0.8 to 3.8. When the P / Me ratio approaches 0, the proportion of titanium oxide in the particles produced increases, and the particles become mixed particles of titanium phosphate and titanium oxide. Such mixed particles can be used in the same manner as titanium phosphate single particles.

In the case of producing titanium phosphate particles in which a complex element such as zirconia is added to titanium, the number of moles of titanium alkoxide + complex element alkoxide (M) relative to the number of moles (P) of the phosphorus compound used in the reaction is the same as above.
e ′) ratio (P / Me ′) is 4 or less, preferably 0.
It is set to 8 to 3.8.

With respect to 1 liter of one of both alcohol solutions, the rate of addition of the other solution is 0.1 to 100.
L / min. The particle size of the produced titanium phosphate particles is mainly determined by the addition rate. Therefore, in order to produce titanium phosphate particles having a predetermined particle diameter, the addition rate may be adjusted. For this, the relationship between the addition rate and the particle size of titanium phosphate particles is obtained in advance,
Add at a rate corresponding to the desired particle size. Generally, as the addition speed becomes faster, the particle size of titanium phosphate particles produced becomes smaller. If the addition rate is less than 0.1 l / min,
Since the average particle diameter of the titanium phosphate produced exceeds 2000 nm and becomes too large, dispersibility deteriorates when it is used as a surface conditioner for the surface treatment of a metal material, which is not preferable. On the other hand, if the addition rate exceeds 100 liters / minute, the titanium phosphate particles have an average particle size smaller than 30 nm and are likely to aggregate, which is not preferable. A more preferable addition rate is 5 to 50 liters / minute.

The addition was carried out in air or under a nitrogen atmosphere at 0
It is preferably carried out at a temperature of up to 70 ° C, especially at a temperature below the boiling point of the solvent. After the addition is completed, the reaction is continued with stirring for about 0.1 to 1 hour. By this reaction, the titanium alkoxide (the alkoxide in the case of containing a composite element) causes a polycondensation reaction with the phosphorus compound, and a white precipitate of titanium phosphate particles is generated. The following equation is the expected reaction mechanism.

[0023]

[Chemical 1]

(2) Method of Separation and Generation After the reaction is completed, the precipitated titanium phosphate particles are isolated by a known method such as centrifugation or filtration. The obtained precipitate is washed with alcohol such as methanol and ethanol and water in that order. For example, 1-5 with alcohol
After washing once, it is washed with distilled water or ion-exchanged water 1 to 5 times.

The washed precipitate is dried by a known method or apparatus such as a freeze-drying method to obtain amorphous titanium phosphate particles. Electron microscope of obtained particles (SE
The average particle size according to M) is 30 to 2000 nm. As mentioned above, this particle size can be controlled by varying the addition rate.

In the above-described method for producing titanium phosphate particles of the present invention, a particularly preferred phosphorus compound is phosphoric acid,
It is at least one selected from the group consisting of orthophosphoric acid, phosphorous acid, diphosphorous acid, metaphosphoric acid, pyrophosphoric acid, an alkyl phosphate having an alkyl group having 1 to 4 carbon atoms, and an alkali phosphate. Particularly preferred titanium alkoxides are Ti (OCH ₃ ) ₄ and Ti (OC
₂ H ₅ ) ₄ , Ti (O-i-C ₃ H ₇ ) ₄ and Ti (O
-T-C ₄ H ₉₎ is at least one selected from the group consisting of _4.

Further, in the present invention, it is preferable to contain 0.5 to 2.0 moles of zirconium element and / or aluminum element as a composite element with respect to 1 mole of titanium. In this case, it is preferable that the concentration of titanium alkoxide in the alcohol mixed solution is 0.05 to 1.0 mol / liter and the concentration of alkoxide of the composite element is 0.05 to 1.0 mol / liter. Further, the ratio (P / M) of the number of moles of the phosphorus compound (P) to the total number of moles of the titanium alkoxide and the alkoxide of the complex element (Me ′).
It is preferable that e ') is 4.0 or less.

[0028]

In the method of the present invention, titanium alkoxide is used as the titanium compound, phosphoric acid, phosphoric acid ester or the like is used as the phosphorus compound, and the reaction solvent is alcohol. OP
Forming a polymer having a —O—Ti bond as a repeating unit,
Generate titanium phosphate particles. At this time, if the ratio of the number of moles of phosphorus to be added and the number of moles of titanium added is within the range of the present invention, a high yield can be obtained.

Although the reaction mechanism has not been completely clarified yet, when the alcohol solutions of both reactants are added and mixed, the rate of addition mainly determines the particle size of titanium phosphate particles. I understood. Therefore, titanium phosphate particles having a desired particle size can be obtained by adjusting the addition rate of the alcohol solution of both reactants.

[0030]

The present invention will be described in more detail by the following specific examples. Example 1 In a 300 ml Erlenmeyer flask, 2.28 g of Ti (OC
₂ H ₅ ) ₄ and ethanol are added and dissolved to a concentration of 0.2
50 ml of a mol / l titanium alkoxide ethanol solution was prepared. Next, 0.70 g of phosphoric acid, 45 g of ion-exchanged water, and ethanol in a total amount of 50 ml were added to a 50 ml graduated cylinder to prepare 50 ml of a phosphoric acid ethanol solution having a concentration of 0.14 mol / liter. Table 1 shows the molar concentrations of the titanium alkoxide ethanol solution and the phosphoric acid ethanol solution, and the P / Me ratio, which is the molar ratio of phosphorus and titanium.

While stirring the ethanol solution of titanium alkoxide, the ethanol solution of phosphoric acid was added dropwise at a rate of 50 liters / minute, and the mixture was stirred at room temperature for 1 hour for reaction. After the reaction was completed, the precipitated white suspension was collected by centrifugation, washed twice with ethanol and twice with ion-exchanged water, and then freeze-dried to obtain titanium phosphate particles.

The obtained titanium phosphate particles were first analyzed by an X-ray diffractometer. As a result, it was found that the particles were in an amorphous state but crystallized into Ti ₃ (PO ₄ ) ₄ by applying heat. Next, ICP analysis of titanium phosphate particles (In
As a result of conducting ductively coupled plasma analysis, the molar ratio of phosphorus atoms and titanium atoms in the particles was 0.7, which was the same as the raw material compounding ratio. The number of moles of titanium in the obtained particles is Ti (A), and the number of moles of titanium used as a raw material is Ti (B).
Formula: Yield (%) = 100 × Ti (A) / Ti (B) As a result of calculating the yield, the yield of the synthesis reaction is 89.3%.
Met.

Further, as a result of observation with an electron microscope, it was found that the obtained particles were monodisperse spherical.
The average particle size of the particles obtained from an electron microscope (SEM) is 21.
It was 1 nm. Table 1 shows the average particle size of the particles obtained and the yield of the synthesis reaction.

Examples 2 to 14 Ti (OC ₂ H ₅ ) ₄ , Ti as titanium alkoxide
_{(O-i-C 3 H} 7) 4 or their and Zr (O-t-C
Phosphoric acid or ethyl phosphate was used as the phosphorus compound in the combination of ₄ H ₉ ) ₄ . Alcohol solutions having the concentrations shown in Table 1 were prepared in the same manner as in Example 1, and the phosphorus compound solution was added dropwise to the alkoxide solution at a rate of 50 liters / minute to react with each other to synthesize titanium phosphate particles.
Analysis was performed by the same method as in Example 1 to determine the particle size and reaction yield of each, and the results are also shown in Table 1.

Example 15 In a 300 ml Erlenmeyer flask, 0.70 g of phosphoric acid, 45
g ion-exchanged water and ethanol were added to give a concentration of 0.14
50 ml of a mol / l ethanolic phosphate solution was prepared. Next, in a 50 ml graduated cylinder, 2.28 g of Ti
(OC ₂ H ₅ ) ₄ and ethanol were added and dissolved to prepare 50 ml of a titanium alkoxide ethanol solution having a concentration of 0.2 mol / liter.

While stirring the ethanol solution of phosphoric acid,
An ethanol solution of titanium alkoxide was added dropwise at a rate of 50 liters / minute, and mixed and stirred at room temperature for 1 hour to cause a reaction. After the reaction was completed, the precipitated white suspension was collected by centrifugation, washed twice with ethanol and twice with ion-exchanged water, and then freeze-dried to obtain titanium phosphate particles. Analysis was performed by the same method as in Example 1 to determine the particle size and reaction yield of each, and the results are also shown in Table 1.

[0037]

[Table 1]

Comparative Examples 1 to 11 Ti (OC ₂ H ₅ ) ₄ , Ti as titanium alkoxide
_{(O-i-C 3 H} 7) 4 or Ti (OC ₂ H _{5) 4} and Z
The combination of _{r (O-t-C 4} H 9) 4, was used phosphate or ethyl phosphate, respectively as a phosphorus compound. Table 2
Alcohol solutions having the concentrations shown in Table 1 were prepared in the same manner as in Example 1, and the phosphorus compound solution was added dropwise to the alkoxide solution at a rate of 50 liters / minute for reaction to synthesize titanium / zirconium composite phosphate particles. The analysis was performed in the same manner as in Example 1, the average particle size and the reaction yield of each were obtained, and the results are shown in Table 2 together. However, since the amount of particles obtained in Comparative Examples 1 to 10 was small, the particle size could not be measured. The particles obtained in Comparative Example 11 are titanium oxide particles.

[0039]

[Table 2]

Examples 16 to 15 Ti (OC ₂ H ₅ ) ₄ , Ti as titanium alkoxide
_{(O-i-C 3 H} 7) 4 or their and Zr (O-t-C
_{The 4} H ₉ ) _{4 combination} used phosphoric acid or ethyl phosphate as the phosphorus compound. Alcohol solutions having the concentrations shown in Table 3 were prepared in the same manner as in Example 1, and the phosphorus compound solution was added dropwise to the alkoxide solution at the rate shown in Table 3 to cause reaction, to synthesize titanium phosphate particles. Analysis was performed in the same manner as in Example 1 to determine the particle size and reaction yield of each, and the results are also shown in Table 3.

[0041]

[Table 3]

Comparative Examples 12 to 17 Ti (OC ₂ H ₅ ) ₄ , Ti as titanium alkoxide
_{(O-i-C 3 H} 7) 4 or Ti (OC ₂ H _{5) 4} and Z
The combination of _{r (O-t-C 4} H 9) 4, using phosphoric acid or ethyl phosphoric acid as a phosphorus compound. Alcohol solutions having the concentrations shown in Table 4 were prepared in the same manner as in Example 1, and the phosphorus compound solution was added dropwise to the alkoxide solution at the rate shown in Table 4 to cause reaction, to synthesize titanium phosphate particles.
Analysis was performed in the same manner as in Example 1 to determine the particle size and reaction yield of each, and the results are also shown in Table 4. However, since the reaction product gelled, the particle size could not be measured.

[0043]

[Table 4]

As can be seen from Tables 1 and 3, Example 1
Titanium phosphate having a particle size of 38 to 1295 nm was obtained at ~ 26. Example 1 and Example 15 have the same concentration of the alcohol solution of titanium alkoxide and phosphoric acid, but the solutions to be dropped are different. However, the yields of the titanium phosphate particles produced and the reaction were almost the same. In addition, Example 1
As is clear from 6 to 23, it was found that the particle size decreased as the addition rate increased.

On the other hand, as can be seen from Tables 2 and 4, P
In Comparative Examples 1 to 10 in which the / Me ratio exceeded 4, the reaction yield was extremely low and the particle size could not be measured. Also,
In Comparative Examples 12 to 17 in which the concentrations of the titanium alkoxide solution and / or the phosphorus compound solution exceeded 2.0 mol / liter and 5.6 mol / liter, respectively, the reaction product gelled, and titanium phosphate particles were obtained. I couldn't do it. Comparative Example 11 is an example using only titanium alkoxide,
The produced particles are particles of titanium oxide.

The concentration of titanium alkoxide is 0.2 mol /
While keeping the liter constant, the molar concentration of phosphoric acid is changed from 0 to 1.0 mol / liter, that is, the P / Me ratio is 0 to
The value was changed to 5.0 and the relationship with the reaction yield at that time was determined. FIG. 1 shows Examples 1 to 4, Examples 7 to 8 and Comparative Examples 4 to 5.
And the relationship between the reaction yield and the P / Me ratio of Comparative Example 11 is shown. From FIG. 1, it can be seen that the reaction yield sharply decreases when the P / Me ratio exceeds 4. The titanium alkoxide concentration was 0.2 mol / liter, and the phosphoric acid concentration was 0.
It was fixed at 72 mol / liter and the mixing speed of both solutions was set to 0.
Example 1 changed to a range of 5 to 50 (liter / minute)
The relationship between the particle size of 6 to 23 and the mixing speed is shown. By using this correlation diagram, titanium phosphate particles having a desired particle diameter can be synthesized.

In Examples 13, 14 and 26, composite metal phosphates of titanium and zirconium were synthesized, but good amorphous particles could all be obtained.

[0048]

As described in detail above, according to the method for producing titanium phosphate amorphous particles of the present invention, a high reaction yield is obtained, and the particle size of titanium phosphate particles produced is controlled. be able to.

The titanium phosphate amorphous particles obtained in the present invention are a surface preparation agent for pretreatment of metal materials, a rust preventive pigment,
It is preferably used for electronic materials.

[Brief description of drawings]

FIG. 1 is a graph showing the relationship between P / Me ratio and reaction yield.

FIG. 2 is a graph showing the relationship between the addition rate of a phosphorus compound and the particle size of titanium phosphate particles produced.

Claims (2)

[Claims] 1. A method of producing titanium phosphate amorphous particles by mixing a titanium alkoxide and a phosphorus compound, hydrolyzing them, and conducting a polycondensation reaction, wherein Ti (OR) ₄ (where R is carbon At least one kind of the titanium alkoxide represented by the formula 1 to 5) is dissolved in alcohol to prepare a solution having a concentration of 0.1 to 2.0 mol / liter. Dissolved to a concentration of 0.01-5.
A 6 mol / liter solution was prepared, and the number of moles of the phosphorus compound (P) and the number of moles of the titanium alkoxide (Me) were adjusted.
A method comprising mixing the titanium alkoxide solution and the phosphorus compound solution and reacting them so that the ratio (P / Me) thereof is 4.0 or less. 2. The method for producing titanium phosphate amorphous particles according to claim 1, wherein the rate at which one of the titanium alkoxide solution and the phosphorus compound solution is added to the other solution is A method characterized in that the particle size of titanium phosphate amorphous particles produced is controlled by adjusting 1 liter of one solution to 0.1 to 100 liters / minute of the other solution.