Method for producing titanate aggregates

Abstract

To provide a method for producing a titanate aggregate using titanium oxychloride as a raw material which can be suitably used as a precursor for a titanium oxide or a titanium multiple oxide, and having a secondary particle size in a micron order and a narrow particle size distribution, in high yield.SOLUTION: A method for producing a titanate aggregate includes: a first step of mixing a titanium oxychloride aqueous solution with sulfuric acid and / or sulfate in a ratio of 5 to 40 mol% sulfuric acid and / or sulfate relative to 100 mol% of a Ti element included in the titanium oxychloride; and a second step of heating the solution obtained in the first step to obtain a hydrolysis product.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a method for producing titanate aggregates.

Background Art

[0002] Composite oxides of titanium such as lithium titanate, barium titanate, and potassium titanate are synthesized by a dry process or a wet process using titanium oxide or metatitanic acid (TiO(OH)2), titanic acid (Ti(OH)4) as precursors and these precursors and lithium salts, barium salts, potassium salts. At this time, since elements such as lithium and potassium promote grain growth as a fluxing agent, it is important to appropriately control the particle shape and particle size of the precursor in order to control the physical properties of the target titanium composite oxide.

[0003] In the production of titanium composite oxides, titanium oxide (TiO2) is generally often used among the above precursors, but it is difficult to produce titanium oxide having a particle size of 1 μm or more, and commercially available titanium oxide is limited to several nanometers to submicron size. For this reason, it is not easy to produce a titanate having a uniform particle size and a particle size of 1 μm or more, which is useful when assuming filler applications or electrode material applications, using commercially available titanium oxide as a raw material, and a composite oxide with other elements. Here, the present inventors have focused on the fact that titanium oxides such as metatitanic acid and titanic acid (hereinafter referred to as titanic acid) form secondary particles in which fine primary particles are aggregated by van der Waals forces, and by adjusting the primary particle diameter and secondary particle diameter of these titanate aggregates, it has been found that the reaction of the primary particles inside the secondary particles can be preferentially advanced, and sintering between the secondary particles can be efficiently suppressed or controlled. By doing so, it has been found that a composite oxide of titanium oxide having a particle diameter of 1 μm or more with a narrow particle size distribution and other elements can be produced by using a titanate aggregate that is (I) an aggregated particle composed of fine primary particles, (II) has a secondary particle diameter on the micron order, and further (III) has a narrow particle size distribution.

[0004] The titanate aggregate can be produced by a method of hydrolyzing titanyl sulfate or titanium oxychloride. Furthermore, titanium oxide can be produced by firing the titanate aggregate. Patent Document 1 discloses that a well-sized metatitanate aggregate is formed by adding a chloride salt in the hydrolysis step of titanyl sulfate. Non-Patent Document 1 discloses the formation of titanyl sulfate by hydrolyzing titanium oxychloride with sulfuric acid. Furthermore, Non-Patent Document 2 discloses a method of producing titanium oxide by hydrolyzing titanium chloride with an acid, and Patent Documents 2 and 3 disclose methods of producing titanium oxide by hydrolyzing titanium oxychloride with an acid.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

Patent Document 3

Non-Patent Documents

[0006]

Non-Patent Document 1

Non-Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0007] Although the method for producing titanate aggregates is disclosed as described above, since titanyl sulfate used in Patent Document 1 contains impurities such as iron and niobium, the range of use and fields of the obtained titanic acid are limited, which is not preferable. Further, in Non-Patent Document 2, Patent Documents 2 and 3, methods for obtaining titanium oxide using highly pure titanium oxychloride as a raw material are disclosed, but none of them disclose a method for obtaining titanate aggregates satisfying the above (I) to (III) with a high yield.

[0008] In view of the above situation, an object of the present invention is to provide a method for producing titanate aggregates having a micron-order secondary particle diameter and a narrow particle size distribution with a high yield, which can be suitably used as a precursor of titanium oxide or a composite oxide of titanium using titanium oxychloride as a raw material.

Means for Solving the Problems

[0009] The present inventors have studied a method for producing titanate aggregates having a micron-order secondary particle diameter and a narrow particle size distribution with a high yield using titanium oxychloride as a raw material. Then, in a production method using titanium oxychloride as a raw material, a titanium oxychloride aqueous solution is mixed with sulfuric acid and / or a sulfate at a predetermined ratio, or a titanium oxychloride aqueous solution is mixed with an acid so that 80 mol% or more of the total amount of the acid is hydrogen chloride, and the obtained solution is heated to obtain a hydrolyzate. It has been found that titanate aggregates having a micron-order secondary particle diameter and a narrow particle size distribution can be produced with a high yield, and the present invention has been completed.

[0010] That is, the present invention is as follows. [1] In the first step, an aqueous titanium oxychloride solution is mixed with sulfuric acid and / or a sulfate at a ratio such that the sulfuric acid and / or the sulfate is 5 to 40 mol% with respect to 100 mol% of the Ti element contained in the titanium oxychloride. And a second step of heating the solution obtained in the first step to obtain a hydrolyzate. A method for producing a titanium acid aggregate, characterized by the above.

[0011] [2] The method for producing a titanium acid aggregate according to [1], wherein the sulfate is at least one selected from the group consisting of sodium sulfate, potassium sulfate, magnesium sulfate, and ammonium sulfate.

[0012] [3] A first step of mixing an aqueous titanium oxychloride solution with an acid, And a second step of heating the solution obtained in the first step to obtain a hydrolyzate, wherein 80 mol% or more of the total amount of the acid mixed in the first step is hydrogen chloride. A method for producing a titanium acid aggregate, characterized by the above.

[0013] [4] The second step includes a preheating step of preheating and holding the solution obtained in the first step, and a hydrolysis step of further heating after the preheating step to obtain a hydrolyzate. The method for producing a titanium acid aggregate according to any one of claims [1] to [3], characterized by the above.

[0014] [5] The method for producing a titanium acid aggregate according to any one of claims [1] to [4], wherein the concentration of TiO2 in the aqueous titanium oxychloride solution used in the first step is 70 to 300 g / L.

[0015] [6] In the first step, at least one selected from the group consisting of sodium chloride, potassium chloride, sodium sulfate, and potassium sulfate is further mixed. The method for producing a titanium acid aggregate according to any one of claims [1] to [5], characterized by the above.

Advantages of the Invention

[0016] The method for producing the titanium acid aggregate of the present invention uses titanium oxychloride as a raw material and is a useful method capable of producing titanium acid aggregates having a secondary particle diameter on the micron order and a narrow particle size distribution.

Brief Description of the Drawings

[0017]

Figure 1

Modes for Carrying Out the Invention

[0018] Hereinafter, preferred embodiments of the present invention will be specifically described. However, the present invention is not limited only to the following description, and can be appropriately modified and applied without changing the gist of the present invention.

[0019] The production of titanium acid aggregates is generally carried out by adding an aqueous solution of a basic compound such as sodium hydroxide to an aqueous solution of titanium oxychloride and subjecting it to hydrolysis. However, the hydrolysis reaction under basic conditions has a high reaction rate, the precipitation of titanic acids proceeds all at once, and titanium acid aggregates with a uniform particle size distribution cannot be obtained. On the other hand, in the method for producing titanium acid aggregates of the present invention, hydrolysis is carried out using sulfuric acid and / or sulfate at a predetermined ratio, or an acid in which 80 mol% or more of the total amount of substances of the acid mixed with titanium oxychloride is hydrogen chloride, whereby titanium acid aggregates with a narrower particle size distribution can be obtained compared to the case where a basic compound is used.

[0020] The manufacturing method of the titanium acid aggregate of the present invention includes a first step of mixing an aqueous solution of titanium oxychloride with sulfuric acid and / or a sulfate at a ratio such that the sulfuric acid and / or the sulfate is 5 to 40 mol% with respect to 100 mol% of the Ti element contained in the titanium oxychloride, and a second step of heating the solution obtained in the first step to obtain a hydrolyzate, and a first step of mixing an aqueous solution of titanium oxychloride with an acid in which 80 mol% or more of the total amount of the acid is hydrogen chloride, and a second step of heating the solution obtained in the first step to obtain a hydrolyzate. Hereinafter, the former manufacturing method will also be described as the first manufacturing method of the titanium acid aggregate of the present invention, and the latter manufacturing method will also be described as the second manufacturing method of the titanium acid aggregate of the present invention, and the combination of both will be described as the manufacturing method of the titanium acid aggregate of the present invention. Since the second steps of the first manufacturing method of the titanium acid aggregate of the present invention and the second manufacturing method of the titanium acid aggregate of the present invention are common, hereinafter, after describing the first steps of the first and second manufacturing methods of the titanium acid aggregate of the present invention respectively, the common second step will be described.

[0021] 1. First step of the first manufacturing method of the titanium acid aggregate of the present invention The first step of the first manufacturing method of the titanium acid aggregate of the present invention is a step of mixing an aqueous solution of titanium oxychloride with sulfuric acid and / or a sulfate. Titanium oxychloride (TiOCl2) undergoes hydrolysis even without mixing with sulfuric acid and / or a sulfate to form titanic acid (TiO(OH)2, Ti(OH)4, etc.), but the reaction rate is slow. On the other hand, when titanium oxychloride is mixed with sulfuric acid and / or a sulfate, TiOSO4 is generated in the reaction system. Since the sulfonyl group (-SO4) in TiOSO4 has a high affinity for water and is prone to reaction, TiOSO4 is considered to be more prone to hydrolysis than titanium oxychloride. Therefore, in the first step, by mixing titanium oxychloride with sulfuric acid and / or a sulfate, the hydrolysis in the second step can proceed sufficiently. After hydrolysis, sulfate ions (SO4 2- ) are desorbed and TiO(OH)2 is formed, so the sulfate ions will function as a catalyst. Note that titanium oxychloride (TiOCl2) is produced by the reaction of titanium tetrachloride with water. Therefore, when using titanium tetrachloride in an aqueous solution, it is equivalent to using an aqueous solution of titanium oxychloride.

[0022] In the above first step, sulfuric acid and / or sulfate is used in a proportion of 5 to 40 mol% with respect to 100 mol% of Ti element contained in the aqueous solution of titanium oxychloride. In order to obtain titanium acid aggregates with a narrow particle size distribution, it is desirable to allow the hydrolysis of titanium oxychloride to proceed at a constant reaction rate and gradually precipitate titanic acids. By using sulfuric acid and / or sulfate in such a proportion, titanium acid aggregates with a narrow particle size distribution can be obtained. Also, if the amount of sulfuric acid and / or sulfate used is too large, titanium sulfate (Ti(SO4)2) may be formed due to chemical equilibrium, which is considered to suppress the progress of the hydrolysis reaction. In addition, the reverse reaction of titanic acid to titanyl sulfate (TiO(SO4)) may proceed, which may reduce the yield of titanium acid aggregates. The amount of sulfuric acid and / or sulfate used is preferably in a proportion of 7 to 20 mol%, more preferably 8 to 18 mol%, with respect to 100 mol% of titanium oxychloride.

[0023] Examples of the above sulfate include salts of Group 1 metals in the periodic table such as sodium and potassium; salts of Group 2 metals in the periodic table such as magnesium and calcium; ammonium salts, etc. One or more of these can be used. Among these, the sulfate is preferably at least one selected from the group consisting of sodium sulfate, potassium sulfate, magnesium sulfate, and ammonium sulfate.

[0024] As the aqueous solution of titanium oxychloride used in the above first step, a commercially available aqueous solution of titanium oxychloride (aqueous solution of titanium tetrachloride) can be used as it is, or a solution prepared by adding pure water to titanium tetrachloride can be used, or a solution prepared by appropriately mixing pure water with the aqueous solution of titanium oxychloride to adjust the concentration can be used. There is no particular limitation on the method for preparing the aqueous solution of titanium oxychloride, and it can be prepared by a conventional method.

[0025] The concentration of the titanium oxychloride aqueous solution used in the above first step is preferably such that the concentration as TiO2 in the titanium oxychloride aqueous solution is 70 to 300 g / L. By using such a concentration, the production efficiency in one batch of reaction can be enhanced, leading to a reduction in production cost. The concentration as TiO2 in the titanium oxychloride aqueous solution is more preferably 100 to 200 g / L, and even more preferably 130 to 160 g / L.

[0026] In the above first step, it is preferable to further mix at least one additive selected from the group consisting of sodium chloride, potassium chloride, sodium sulfate, and potassium sulfate. When using at least one of these, the aggregated particle size of the titanic acid aggregates produced can be arbitrarily controlled by adjusting the addition amount. The addition amount when using these may be arbitrarily adjusted according to the required aggregated particle size of the titanic acid aggregates, but it is preferably 0.16 to 40.0 g with respect to 100 mL of the titanium oxychloride aqueous solution used in the first step. More preferably, it is 0.26 to 17.0 g, and even more preferably 0.30 to 4.0 g.

[0027] In the above first step, sulfuric acid and / or sulfate may be added to the titanium oxychloride aqueous solution and mixed, or the titanium oxychloride aqueous solution may be added to sulfuric acid and / or sulfate and mixed, or the titanium oxychloride aqueous solution and sulfuric acid and / or sulfate may be added to the reaction vessel together and mixed. In any of these cases, the addition method is not particularly limited and may be a batch addition, or a divided addition or a continuous addition. The same applies to the case of mixing at least one additive selected from the group consisting of sodium chloride, potassium chloride, sodium sulfate, and potassium sulfate in the first step.

[0028] 2. The first step of the method for producing titanic acid aggregates of the second invention of the present invention The first step of the method for producing the titanium acid aggregate of the second invention is a step of mixing an aqueous titanium oxychloride solution and an acid, and it is characterized in that 80 mol% or more of the total amount of the acid mixed in the first step is hydrogen chloride. Similar to the method for producing the titanium acid aggregate of the first invention described above, hydrolysis in the second step can be promoted by mixing the acid so that 80 mol% or more of the total amount of the acid in the first step is hydrogen chloride. In the first step, it is preferable to use the acid in a proportion of 10 to 100 mol% with respect to 100 mol% of the Ti element contained in the aqueous titanium oxychloride solution. More preferably, it is used in a proportion of 15 to 80 mol%, and still more preferably, it is used in a proportion of 20 to 60 mol%. Note that since the aqueous titanium oxychloride solution contains free hydrogen chloride, pay attention to appropriately adjusting the total amount of the added acid and the free hydrogen chloride contained in the stock solution of the aqueous titanium oxychloride solution so that it becomes the above ratio.

[0029] Among the total amount of the acid mixed in the first step of the method for producing the titanium acid aggregate of the second invention described above, 80 mol% or more is hydrogen chloride, but preferably 85 mol% or more is hydrogen chloride. More preferably, it is 90 mol% or more.

[0030] The concentration of the aqueous titanium oxychloride solution used in the first step of the method for producing the titanium acid aggregate of the second invention described above is preferably the same as that of the method for producing the titanium acid aggregate of the first invention described above. Also, in the method for producing the titanium acid aggregate of the second invention, similar to the method for producing the titanium acid aggregate of the first invention, in the first step, it is preferable to further mix at least one additive selected from the group consisting of sodium chloride, potassium chloride, sodium sulfate, and potassium sulfate, and the preferable addition amount is also the same as in the case of the method for producing the titanium acid aggregate of the first invention.

[0031] In the first step of the second method for producing the titanium acid aggregate of the present invention, an acid may be added to and mixed with the titanium oxychloride aqueous solution, the titanium oxychloride aqueous solution may be added to and mixed with the acid, or the titanium oxychloride aqueous solution and the acid may be added to the reaction vessel together and mixed. In any of these cases, the addition method is not particularly limited, and it may be a batch addition, or a divided addition or a continuous addition. The same applies to the case of mixing at least one additive selected from the group consisting of sodium chloride, potassium chloride, sodium sulfate, and potassium sulfate in the first step.

[0032] 3. Second Step of the Method for Producing the Titanium Acid Aggregate of the Present Invention The second step of the method for producing the titanium acid aggregate of the present invention is a step of heating the solution obtained in the first step to obtain a hydrolyzate. In the second step, the temperature for heating the solution obtained in the first step is not particularly limited as long as hydrolysis proceeds, but it is preferably 70 to 120°C. More preferably, it is 80 to 115°C, and still more preferably, it is 90 to 110°C. Also, considering sufficient progress of hydrolysis and production efficiency, the heating time of the solution obtained in the first step is preferably 1 to 6 hours. More preferably, it is 1.5 to 5 hours, and still more preferably, it is 2 to 4 hours.

[0033] The above second step only needs to be a step of heating the solution obtained in the first step, but it preferably includes a preheating step of preheating and holding the solution obtained in the first step, and a hydrolysis step of further heating at a higher temperature after the preheating step to obtain a hydrolyzate. In this way, by first preheating the solution obtained in the first step and then performing a step of raising the temperature and causing hydrolysis, it is also possible to control the size of the obtained titanium acid aggregate. Therefore, by combining such a production method with the size control of the titanium acid aggregate by adding an additive such as sodium chloride, it is possible to more precisely control the size of the titanium acid aggregate. When performing such two-stage heating in the second step, the temperature in the preheating step is preferably 60 to 110 °C. More preferably, it is 65 to 85 °C, and still more preferably, it is 70 to 80 °C. Also, the temperature in the hydrolysis step after preheating is preferably 90 to 120 °C. More preferably, it is 95 to 115 °C, and still more preferably, it is 100 to 110 °C. In the second step, when performing a preheating step and a hydrolysis step of further heating after the preheating step to obtain a hydrolyzate, the time for performing the preheating step is preferably 0.25 to 1.5 hours. More preferably, it is 0.3 to 1.25 hours, and still more preferably, it is 0.5 to 1.0 hours. Also, the time for performing the hydrolysis step of further heating after the preheating step to obtain a hydrolyzate is preferably 1 to 5 hours. More preferably, it is 1.5 to 4 hours, and still more preferably, it is 2 to 3 hours.

[0034] 4. Other steps of the method for producing the titanate aggregate of the present invention

[0035] The method for producing the titanate aggregate of the present invention preferably includes a step of neutralizing the acidic compound contained in the hydrolyzate obtained in the above second step. Thereby, acid ions such as sulfate ions and chloride ions remaining in the titanate aggregate can be efficiently removed. The neutralization step can be performed by adding a basic compound to the hydrolyzate. The basic compound used for neutralization is not particularly limited, and ammonia, sodium hydroxide, sodium carbonate, sodium hydrogen carbonate, potassium hydroxide, etc. can be used. Among these, ammonia, sodium hydroxide, sodium carbonate, and sodium hydrogen carbonate are preferable in that the basic compound itself and the salt generated by neutralization are water-soluble. More preferably, it is ammonia. These may be added in a solid or gaseous state, but usually, they are added as an aqueous solution.

[0036] In the above neutralization step, it is preferable to add a basic compound until the pH of the repulped slurry obtained by repulping the hydrolyzate in water 1 to 100 times the mass of the hydrolyzate reaches 7 to 10. Thereby, a compound composed of acid ions such as sulfate ions and chloride ions forms a salt, and the water solubility is improved, so that the acid ions can be removed more efficiently. More preferably, a basic compound is added until the pH of the repulped slurry reaches 8 to 9.

[0037] In the method for producing the titanate aggregate of the present invention, after the hydrolysis step, it is preferable to perform a step of filtering and washing with water before subjecting the obtained hydrolyzate to the neutralization step. The washing with water of the hydrolyzate is preferably performed until the electric conductivity of the water used for washing with water becomes 1000 μS / cm or less, whereby unnecessary sulfates and chloride salts contained in the hydrolyzate can be sufficiently removed.

[0038] Also, in the method for producing the titanate aggregate of the present invention, after the neutralization step, it is preferable to perform a step of filtering and washing with water on the obtained solid matter. Thereby, the salt generated in the neutralization step can be removed, and the purity of the titanate aggregate can be increased. The washing with water of the neutralized product is preferably performed until the electric conductivity of the water used for washing with water becomes 1000 μS / cm or less, whereby the salt generated in the neutralization step can be sufficiently removed. More preferably, it is performed until it becomes 500 μS / cm or less, and even more preferably, it is performed until it becomes 100 μS / cm or less.

[0039] After the above neutralization step (after the neutralization step, when performing the step of filtering and washing with water on the obtained neutralized product, after the step of filtering and washing with water), it is preferable to perform a step of drying the obtained titanate aggregate. The method for drying the titanate aggregate is not particularly limited, but it is preferably performed by heating. The temperature during heating is preferably 80 to 200°C. More preferably, it is 100 to 150°C. The time for drying is not limited, but it is preferably 1 to 48 hours. More preferably, it is 2 to 24 hours. By drying at the said temperature and time, it can fully be dried, suppressing the excessive sintering between particles.

[0040] The method for producing the titanate aggregate may include other steps other than the above-described steps. Examples of the other steps include a step of crushing the titanate aggregate after drying and a step of classification.

[0041] 5. Titanate aggregate By producing with the method for producing a titanate aggregate of the present invention, a titanate aggregate having a secondary particle diameter on the micron order and a narrow particle size distribution can be produced at a high yield. The secondary particle diameter of the titanate aggregate produced by the method for producing a titanate aggregate of the present invention is preferably 1 to 25 μm. More preferably, it is 3 to 15 μm, and still more preferably, it is 5 to 10 μm. The secondary particle diameter (D 50 ) can be measured by the method described in the examples below.

[0042] The titanate aggregate produced by the method for producing a titanate aggregate of the present invention is preferably such that D 90 / D 10 is less than 6. More preferably, it is 5 or less, and still more preferably, it is 3 or less. D of the titanate aggregate 90 , D 10 can be measured by the method described in the examples below.

[0043] The titanate aggregate produced by the method for producing a titanate aggregate of the present invention preferably has a specific surface area of 60 to 500 m 2 / g. More preferably, it is 80 to 400 m 2 / g, and still more preferably, it is 150 to 300 m 2 / g. The specific surface area of the titanate aggregate can be measured by the method described in the examples below.

[0044] The titanate aggregate produced by the method for producing a titanate aggregate of the present invention is preferably secondary particles in which fine primary particles are aggregated, and the primary particle size is preferably 2 to 15 nm. More preferably, it is 2.5 to 10 nm, and still more preferably, it is 3 to 9 nm. The primary particle size of the titanate aggregate can be determined by the method described in the examples below.

[0045] The titanate aggregate produced by the method for producing a titanate aggregate of the present invention preferably has an aggregation degree represented by (secondary particle size / primary particle size) of 50 to 3000. More preferably, it is 300 to 1500, and still more preferably, it is 500 to 1300. Thus, a titanate aggregate in which fine primary particles are aggregated to form secondary particles is easy to control the reaction and the physical properties of the product when used as a composite oxide in combination with other elements. When it becomes fine particles that are not aggregated, since the reactivity is high, it becomes difficult to control the size and particle size of the titanium composite oxide, and there is a drawback that the particle size distribution becomes wide particularly when synthesizing a composite oxide of 1 μm or more. On the contrary, when the primary particle size is large, the reactivity is poor and the reaction does not proceed to the inside of the particle, which is also not desirable. The aggregation degree of the titanate aggregate can be determined by the method described in the examples below.

Examples

[0046] Specific examples are given below to explain the present invention in detail, but the present invention is not limited to only these examples. Unless otherwise specified, “%” and “wt%” mean “weight% (mass%)”. The measurement methods for each physical property are as follows.

[0047] <Yield> Assuming the chemical composition of the recovered titanate aggregate is TiO(OH)2, the yield was calculated. In calculating the yield, adsorbed water was not considered. <Particle size distribution> Using a laser diffraction / scattering particle size distribution analyzer (LA-960, manufactured by HORIBA), the particle size distribution was measured for a sample in which a 0.025% aqueous hexametaphosphate solution was used as the dispersion medium and dispersed for 1 minute using an ultrasonic homogenizer (US-600, manufactured by Nippon Seiki Co., Ltd.). In the measurement, the refractive index of water was 1.333 and the refractive index of the titanic acid aggregates was 2.500. <Specific surface area> Using a fully automatic specific surface area analyzer (Macsorb, manufactured by Microtrac), the sample was degassed at 200 °C for 30 minutes, preheated at 200 °C for 5 minutes, and then the specific surface area was measured by adsorption / desorption measurement. <Primary particle size (BET equivalent particle size)> The primary particle size was calculated from the above specific surface area measurement results by the following calculation. Primary particle size (μm) = 6 / (r·S) × 1000 r: Theoretical density (g / cm 3 ), S: Specific surface area (m 2 / g) Here, since the main crystal phase was anatase type in both the examples and comparative examples, the theoretical density was 3.90 g / cm 3 was used. <Secondary particle size, D 90 / D 10 , Degree of aggregation> The following were calculated from the parameters obtained from the above analysis. Median diameter (D 50 ) obtained from the particle size distribution: Secondary particle size D 90 / D 10 : Particle size distribution Secondary particle size / primary particle size: Degree of aggregation <Electron microscope observation> SEM images were taken using a field emission scanning electron microscope (JSM-7000, manufactured by JEOL).

[0048] Example 1 To a reactor equipped with a reflux device, 100 mL of an aqueous titanium tetrachloride solution (manufactured by Osaka Titanium, 16.7 wt% as Ti, 31.5 wt% as Cl, specific gravity 1.56 g / mL) and 2 mL of 95% sulfuric acid (6.5 mol% relative to Ti) were added to 200 mL of pure water and mixed. The mixed solution was heated with stirring and refluxed for 3 hours (temperature: 100 - 110 °C) to carry out the reaction. The obtained slurry was added to a Buchner funnel and suction filtered, and the obtained solid content was washed with running water using 30 L of pure water. The solid content was repulped in pure water, and an aqueous ammonia solution was added until the pH of the repulped slurry reached about 8 - 9. The slurry after pH adjustment was filtered again and washed with running water so that the electrical conductivity of the filtrate was 100 μS / cm or less. The washed solid content was dried at 150 °C and passed through a 300 μm sieve. The yield was calculated from the recovered weight of the obtained powder, and the median diameter, D 90 / D 10 and the specific surface area were measured. The results are shown in Table 1. Also, the electron microscope observation results of the obtained powder are shown in Figure 1.

[0049] Examples 2 - 11, Comparative Examples 1 - 9 Powders were produced in the same manner as in Example 1, except that the amounts of titanium tetrachloride aqueous solution, pure water, sulfuric acid, and the reaction time used were changed as shown in Table 1. The yield was calculated from the recovered weight of the obtained powder, and the median diameter, D 90 / D 10 and the specific surface area were measured. The results are shown in Table 1.

[0050]

Table 1

[0051] Examples 12 - 16, Comparative Examples 10 - 11 Titanate aggregates of Examples 12 - 16 and Comparative Examples 10 - 11 were obtained in the same manner as in Example 1, except that various acids or salts shown in Table 2 were used instead of sulfuric acid. The yield was calculated from the recovered weight of the obtained powder, and the median diameter, D 90 / D 10 and the specific surface area were measured. The results are shown in Table 2.

[0052] Examples 17 - 24 Titanate aggregates of Examples 17 to 24 were obtained in the same manner as in Example 3, except that various additives shown in Table 2 were added in addition to sulfuric acid. The yield was calculated from the recovered weight of the obtained powder, and the median diameter, D 90 / D 10 , and the specific surface area were measured. The results are shown in Table 2.

[0053]

Table 2

[0054] Examples 25 to 32 Titanate aggregates of Examples 25 to 32 were obtained in the same manner as in Example 5, except that sodium chloride (manufactured by N & M SALT, washed natural salt, purity: >98%) was added to the mixed solution before the reaction in the amounts shown in Table 3. The yield was calculated from the recovered weight of the obtained powder, and the median diameter, D 90 / D 10 , and the specific surface area were measured. The results are shown in Table 3.

[0055] Examples 33 to 35 Titanate aggregates of Examples 33 to 35 were obtained in the same manner as in Example 5, except that 5 g of sodium chloride (manufactured by N & M SALT, washed natural salt, purity: >98%) was added to the mixed solution before the reaction, and the mixed solution was stirred at the temperature shown in Table 3 for 1 hour and then refluxed (temperature: 100 to 110 °C) for 2 hours. The yield was calculated from the recovered weight of the obtained powder, and the median diameter, D 90 / D 10 , and the specific surface area were measured. The results are shown in Table 3.

[0056]

Table 3

[0057] Example 36 To a reactor equipped with a reflux device, 100 mL of an aqueous titanium tetrachloride solution (manufactured by Sakai Chemical Industry Co., Ltd., 12.5 wt% as Ti, 40.4 wt% as Cl, specific gravity 1.477 g / mL) and 5 mL of 95% sulfuric acid (23 mol% with respect to Ti) were added to 200 mL of pure water and mixed. The mixed solution was heated and stirred, and refluxed for 3 hours (temperature: 100 - 110 °C) to conduct the reaction. The obtained slurry was added to a Buchner funnel and suction filtered, and the obtained solid content was washed with running water using 30 L of pure water. The solid content was repulped in pure water, and an aqueous ammonia solution was added until the pH of the repulped slurry reached about 8 - 9. The slurry after pH adjustment was filtered again and washed with running water so that the electrical conductivity of the filtrate was 100 μS / cm or less. The washed solid content was dried at 150 °C and passed through a 300 μm sieve. The yield was calculated from the recovered weight of the obtained powder, and the median diameter, D 90 / D 10 , and the specific surface area were measured. The results are shown in Table 4.

[0058] Examples 37 - 40, Comparative Examples 12, 13 Powders were produced in the same manner as in Example 25, except that the amounts of titanium tetrachloride aqueous solution, sulfuric acid, and sodium chloride used were changed as shown in Table 4. The yield was calculated from the recovered weight of the obtained powder, and the median diameter, D 90 / D 10 , and the specific surface area were measured. The results are shown in Table 4.

[0059]

Table 4

Claims

1. A first step of mixing an aqueous titanium oxychloride solution with sulfuric acid and / or a sulfate at a ratio such that the sulfuric acid and / or the sulfate is 5 to 40 mol% with respect to 100 mol% of the Ti element contained in the titanium oxychloride, and a second step of heating the solution obtained in the first step to obtain a hydrolyzate, characterizing a method for producing titanium acid aggregates.

2. The method for producing titanium acid aggregates according to claim 1, wherein the sulfate is at least one selected from the group consisting of sodium sulfate, potassium sulfate, magnesium sulfate, and ammonium sulfate.

3. A first step of mixing an aqueous titanium oxychloride solution with an acid, and a second step of heating the solution obtained in the first step to obtain a hydrolyzate, wherein 80 mol% or more of the total amount of the acid mixed in the first step is hydrogen chloride. characterizing a method for producing titanium acid aggregates.

4. The second step includes a preheating step of preheating and holding the solution obtained in the first step, and a hydrolysis step of further heating after the preheating step to obtain a hydrolyzate. The method for producing titanium acid aggregates according to claim 1 or 3, characterized by the above.

5. The concentration of TiO as titanium oxychloride aqueous solution used in the first step is 70 to 300 g / L, and the method for producing titanium acid aggregates according to claim 1 or 3 is characterized by this. ２ ​

6. In the first step, the method for producing titanium acid aggregates according to claim 1 or 3 is characterized by further mixing at least one selected from the group consisting of sodium chloride, potassium chloride, sodium sulfate, and potassium sulfate.

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