Zirconium hydroxide powder and method for manufacturing zirconium hydroxide powder

Abstract

Zirconium hydroxide powder having a peak top in a pore diameter region of 1 nm or more and 5 nm or less in a pore distribution based on the BJH method, and a pore volume of 0.15 cm³ / g or more in a pore diameter region of 1 nm or more and 5 nm or less.

Description

Technology Field

[0001] The present invention relates to zirconium hydroxide powder and a method for manufacturing zirconium hydroxide powder. Background Technology

[0002] Calcium compounds, such as calcium oxide and calcium chloride, are known as conventional inorganic compounds that exhibit hygroscopic properties. However, due to their chemical properties, calcium compounds generate heat when reacting with water, and the absorbed water is alkaline; therefore, caution is required during handling as they are harmful to the human body.

[0003] Patent Document 1 describes a surface area of ​​at least 300 m² 2 / g, and the total pore volume is at least 0.70cm³ 3 Amorphous zirconium hydroxide is disclosed, which has an average pore size between 5 nm and 15 nm and is / g.

[0004] Patent Document 2 states that in the measurement of the infrared absorption spectrum, 3300–3500 cm -1 at one peak and 1300–1700 cm -1 It has two or more infrared absorption bands, exhibits an X-ray diffraction pattern belonging to the monoclinic system of zirconium oxide after heat treatment at 300–400°C, and has a BET specific surface area of ​​200 m² 2 Zirconium hydroxide with a content of 1 / g or more is disclosed.

[0005] Patent Document 3 describes a crystalline zirconia material composed of tetragonal and monoclinic phases, wherein the specific surface area of ​​the material is 150 to 500 m² 2 A porous crystalline zirconia material with a volume of 0.2 to 1.2 cm² is disclosed. Additionally, a pore volume of 0.2 to 1.2 cm² is disclosed. 3 / g, and it is disclosed that the pore diameter of the pores occupying more than 60% of the volume is 2 to 50 nm.

[0006] Patent Document 4 discloses zirconium oxide hydrate particles represented by the general formula ZrO2·nH2O, wherein the average pore diameter obtained by the nitrogen gas adsorption method of the particles is 1.5 nm or more and 1.75 nm or less, and n in the general formula is a number greater than 2.5, and n is a value measured after dispersing the particles in water, filtering them, and then drying them in air at 60°C for 6 hours. Prior art literature

[0007] Patent Document 1: Japanese Published Patent No. 2009-525250 Patent Document 2: Japanese Published Patent No. 2000-247641 Patent Document 3: Japanese Published Patent No. 2005-35860 Patent Document 4: Japanese Published Patent No. 2009-274897 The problem to be solved

[0008] As mentioned above, there is a need to develop compounds that exhibit high hygroscopicity and can be handled safely due to their low toxicity to the human body.

[0009] The present invention has been made in consideration of the aforementioned problems, and its purpose is to provide zirconium hydroxide powder that exhibits high hygroscopicity and can be safely handled due to its low toxicity to the human body. Additionally, the invention aims to provide a method for manufacturing said zirconium hydroxide powder. means of solving the problem

[0010] The inventors conducted thorough research on zirconium hydroxide powder. As a result, they surprisingly discovered that zirconium hydroxide powder having the following composition exhibits high hygroscopicity and can be safely handled due to its low toxicity to the human body, thereby completing the present invention.

[0011] That is, the zirconium hydroxide powder according to the present invention is,

[0012] In the pore distribution based on the BJH method, there is a peak top in the pore diameter region of 1 nm or more and 5 nm or less, and

[0013] The pore volume in the above pore diameter region of 1 nm or more and 5 nm or less is 0.15 cm 3 It is characterized by being greater than / g.

[0014] According to the above configuration, the absorption of atmospheric moisture is promoted because it has a peak top in the pore diameter region of 1 nm or more and 5 nm or less. The inventors speculate that regarding this phenomenon, fine pores of 1 nm or more and 5 nm or less absorb atmospheric moisture through capillary action. Furthermore, the pore volume in the pore diameter region of 1 nm or more and 5 nm or less is 0.15 cm³ 3 It is greater than / g and can absorb a large amount of moisture from the atmosphere because the proportion of fine pores between 1nm and 5nm is large.

[0015] As such, according to the above configuration, there is a peak top in the pore diameter region of 1 nm or more and 5 nm or less, and furthermore, the pore volume in the pore diameter region of 1 nm or more and 5 nm or less is 0.15 cm 3 Since it is greater than 1g, it can absorb a large amount of moisture from the atmosphere.

[0016] In addition, the amorphous zirconium hydroxide of Patent Document 1 has an average pore size between 5 nm and 15 nm, and does not have a peak top in the pore diameter region of 1 nm or more and 5 nm or less.

[0017] In addition, although not explicitly stated, the zirconium hydroxide of Patent Document 2 may have a peak top in the pore diameter region of 1 nm to 5 nm, while its pore volume is 0.15 cm. 3 Since it is less than / g, it does not have sufficient processing volume.

[0018] In addition, the crystalline zirconia material of Patent Document 3 is disclosed to have a pore diameter of 2 to 50 nm, which accounts for 60% or more of the volume, but the pores are not concentrated in a pore diameter region of 1 nm or more and 5 nm or less. That is, it does not have a peak top in a pore diameter region of 1 nm or more and 5 nm or less.

[0019] In addition, the average pore diameter of the zirconium oxide hydrate particles of Patent Document 4 is 1.5 nm or more and 1.75 nm or less, but the zirconium oxide hydrate particles described in Patent Document 4 contain a relatively large amount of hydrated water within the particles, so the hydrated water present in the pores of 1 nm or more and 5 nm or less increases, and thus the pore volume in the pore diameter region of 1 nm or more and 5 nm or less decreases. That is, the zirconium oxide hydrate particles of Patent Document 4 do not have a sufficient pore volume.

[0020] In addition, the compounds of Patent Documents 1 to 4 do not exhibit hygroscopicity. Furthermore, Patent Documents 1 to 4 do not contain any description regarding hygroscopicity.

[0021] In the above configuration, the pore volume in the pore diameter region of 1 nm or more and 5 nm or less is 0.2 cm 3 It is desirable that it be greater than / g.

[0022] The pore volume in the above pore diameter region of 1 nm or more and 5 nm or less is 0.2 cm 3 If it is 1 / g or more, it can absorb a larger amount of moisture from the atmosphere.

[0023] In the above composition, the apparent density is 0.10 g / cm³ 3 Above 0.25g / cm² 3 It is desirable that it be less than or equal to this.

[0024] Apparent density is 0.25 g / cm³ 3If the value is less than or equal to this, it can be said that the pore volume, which represents the interparticle gap between particles and is greater than or equal to 1,000 nm, is large. As a result, particle aggregation becomes easier to break down, allowing for high dispersion when, for example, it is mixed with other materials. Consequently, it is easy to use for various applications. For example, when mixed with a resin material and used as a hygroscopic agent, it is easy to achieve high dispersion within the resin material.

[0025] In the above configuration, the specific surface area is 350m² 2 It is desirable that it be greater than / g.

[0026] The specific surface area is 350 m² 2 If it is more than / g, it can absorb a larger amount of moisture from the atmosphere.

[0027] In addition, the method for manufacturing zirconium hydroxide powder according to the present invention is,

[0028] The method includes a first drying process for drying a wet cake of zirconium hydroxide produced by a wet method until the solid content concentration becomes 60 mass% or more and 87 mass% or less, and

[0029] The drying conditions in the first drying process above are characterized by the fact that the rate of increase in solid content concentration is within the range of 5 mass% / h or more and 120 mass% / h or less.

[0030] By adopting relatively calm conditions as the drying conditions in the first drying process above, that is, drying conditions in which the rate of increase of solid content is within the range of 120 mass% / h or less, it becomes possible to easily obtain zirconium hydroxide powder having a peak top in a pore diameter region of 1 nm or more and 5 nm or less.

[0031] Regarding this point, the inventors of the present invention speculate as follows.

[0032] Zirconium hydroxide powder consists of secondary particles formed by the aggregation of primary particles.

[0033] The above first drying process is an initial drying process until the solid content concentration of the wet cake becomes 60 mass% or more and 87 mass% or less.

[0034] If severe conditions, that is, drying conditions in which the rate of increase of solid content exceeds 120 mass% / h, are adopted as the drying conditions in the first drying process above, the water in the secondary particles of zirconium hydroxide in the state of a wet cake evaporates rapidly. As a result, the force to aggregate due to surface tension increases all at once, and the water aggregates to fill the places where it was present, causing the fine pores to disappear.

[0035] On the other hand, if a relatively mild condition is adopted as the drying condition in the first drying process, that is, a drying condition in which the rate of increase of solid content is within the range of 120 mass% / h or less, the cohesive force decreases when water in the secondary particles of zirconium hydroxide in the wet cake state evaporates, so the places where water was present remain as holes without being crushed. As a result, a large number of pores of 1 nm or more and 5 nm or less are formed.

[0036] In addition, by adopting a drying condition in which the rate of increase of solid content concentration in the first drying process is within the range of 5 mass% / h or more, it becomes possible to easily obtain zirconium hydroxide powder having a peak top in a pore diameter region of 1 nm or more and 5 nm or less.

[0037] Regarding this point, the inventors of the present invention speculate as follows.

[0038] If the rate of increase in the solid content concentration in the first drying process is less than 5 mass% / h, water in the secondary particles evaporates and, in the process of forming fine pores, aggregation between primary particles due to hydrogen bonding is likely to proceed, and as a result, the fine pores disappear.

[0039] On the other hand, if the rate of increase in the solid content concentration in the first drying process is 5 mass% / h or more, the evaporation of water proceeds faster than the formation of a hydrogen bond network, so the aggregation of primary particles is suppressed, and as a result, a large number of fine pores of 1 nm or more and 5 nm or less are formed.

[0040] In the above configuration, it is preferable to include a second drying process after the first drying process, wherein the solid content concentration of the wet cake is dried until it exceeds 87 mass% and is 92 mass% or less.

[0041] By including the above second drying process, the final moisture content of the zirconium hydroxide powder can be adjusted to a solid content concentration of more than 87 mass% and less than or equal to 92 mass%. Effects of the invention

[0042] According to the present invention, it is possible to provide zirconium hydroxide powder that exhibits high hygroscopicity and can be safely handled due to its low toxicity to the human body. Additionally, a method for manufacturing said zirconium hydroxide powder can be provided. Brief explanation of the drawing

[0043] Figure 1 shows the pore distribution of zirconium hydroxide powder of the example and comparative example. Specific details for implementing the invention

[0044] Embodiments of the present invention will be described below. However, the present invention is not limited to these embodiments. Also, in this specification, zirconia refers to a general type containing 10 mass% or less of an impurity metal compound including hafnia (except in cases where WO3 is included).

[0045] [Zirconium Hydroxide Powder]

[0046] The zirconium hydroxide powder according to the present embodiment has a peak top in the pore diameter region of 1 nm or more and 5 nm or less in the pore distribution based on the BJH method. Because it has a peak top in the pore diameter region of 1 nm or more and 5 nm or less, the absorption of moisture from the atmosphere is promoted. Regarding this phenomenon, the inventors speculate that fine pores of 1 nm or more and 5 nm or less absorb moisture from the atmosphere through capillary action.

[0047] The above peak top is preferably located in a pore diameter region of 1.5 nm or more, more preferably in a pore diameter region of 2.0 nm or more, even more preferably in a pore diameter region of 3.0 nm or more, particularly preferably in a pore diameter region of 3.2 nm or more, and especially preferably in a pore diameter region of 3.3 nm or more. The above peak top is preferably located in a pore diameter region of 4.5 nm or less, and more preferably in a pore diameter region of 4 nm or less.

[0048] The above zirconium hydroxide powder has a pore volume (hereinafter, Vp1) in the pore diameter region of 1 nm or more and 5 nm or less. -5 (also called) is 0.15cm 3 / g or more. Pore volume (Vp1) in the pore diameter region of 1 nm or more and 5 nm or less above. - 5) This is 0.15cm 3 Because the proportion of fine pores between 1 nm and 5 nm is large, it can absorb a large amount of moisture from the atmosphere, with a ratio of more than / g.

[0049] The above Vp1 -5 is preferably 0.2cm 3 / g or more, and more preferably 0.22cm 3 / g or more, more preferably 0.24cm 3 / g or more, particularly preferably 0.25cm 3 / g or more, particularly preferably 0.26cm3 / g or more, particularly preferably 0.27cm 3 / g or more. The above Vp 1-5 The larger it is, the more desirable it is, for example, 0.8cm 3 / g or less, 0.6cm 3 / g or less, 0.4cm 3 / g is less than or equal to etc.

[0050] As such, the zirconium hydroxide powder has a peak top in the pore diameter region of 1 nm or more and 5 nm or less, and additionally, the pore volume in the pore diameter region of 1 nm or more and 5 nm or less is 0.15 cm³ 3 Since it is greater than 1g, it can absorb a large amount of moisture from the atmosphere.

[0051] The above zirconium hydroxide powder has a pore volume (hereinafter, Vp1) in a pore diameter region of 1 nm or more and 50 nm or less. -50 Pore ​​volume (Vp1) in the pore diameter region of 1 nm to 5 nm for (also called) - The ratio of 5)(Vp1 -5 / Vp1 - 50 It is desirable that ) be 0.5 or higher.

[0052] The above ratio (Vp1 -5 / Vp1 - 50 ) is 0.5 or greater, and additionally, the pore volume in the pore diameter region of 1 nm or more and 5 nm or less is 0.15 cm 3 If it is 1 / g or more, it can absorb a larger amount of moisture from the atmosphere.

[0053] The above ratio (Vp1 -5 / Vp1 - 50 ) is more preferably 0.6 or higher, even more preferably 0.65 or higher, and particularly preferably 0.7 or higher. The above ratio (Vp1 -5 / Vp1 - 50 ) is more desirable the larger it is, for example, 1.0 or less, 0.9 or less, etc.

[0054] The above Vp1 -50 It is preferably 0.2cm 3 / g or more, and more preferably 0.25cm 3 / g or more, more preferably 0.3cm 3 / g or more, particularly preferably 0.32cm 3 / g or more, particularly preferably 0.34cm 3 / g or more. The above Vp1 -50 is preferably 1.0 cm 3 / g or less, and more preferably 0.8cm 3 / g or less, more preferably 0.6cm 3 It is less than / g.

[0055] The above zirconium hydroxide powder has a pore volume (hereinafter, Vp) in the total pore diameter region. all (also called) is 0.3cm 3 It is desirable that it be greater than / g, and 0.4cm 3 / g or more is more desirable. The above Vp all 1.2cm 3 It is desirable that it be / g or less, and 1.0cm 3 / g or less is more desirable.

[0056] It is preferable that the above zirconium hydroxide powder has an average pore diameter of 3 nm or more and 6 nm or less. If the average pore diameter is 3 nm or more and 6 nm or less, it can absorb a larger amount of moisture from the atmosphere.

[0057] The above average pore diameter is preferably 3.3 nm or more, more preferably 3.6 nm or more, even more preferably 3.9 nm or more, particularly preferably 4.0 nm or more, especially preferably 4.04 nm or more, and particularly preferably 4.2 nm or more. The above average pore diameter is preferably 5.5 nm or less, and more preferably 5 nm or less.

[0058] The above peak top, the above Vp1 -5, above Vp1 -50 , the above Vp all The above average pore diameter refers to the value obtained by the method described in the example.

[0059] The above zirconium hydroxide powder has an apparent density of 0.10 g / cm³ 3 Above 0.25g / cm² 3 It is desirable that it be less than or equal to an apparent density of 0.25 g / cm³. 3 If the value is less than or equal to this, it can be said that the pore volume, which represents the interparticle gap between particles and is greater than or equal to 1,000 nm, is large. As a result, particle aggregation becomes easier to break down, allowing for high dispersion when, for example, it is mixed with other materials. Consequently, it is easy to use for various applications. For example, when mixed with a resin material and used as a hygroscopic agent, it is easy to achieve high dispersion within the resin material.

[0060] The above apparent density is more preferably 0.23 g / cm³ 3 It is less than or equal to, and more preferably 0.21 g / cm³ 3 Below, particularly preferably 0.19 g / cm³ 3 The above apparent density is preferably as low as possible, for example 0.12 g / cm³. 3 Above, 0.14g / cm² 3 Above, 0.16g / cm² 3 The above is the case.

[0061] The above apparent density refers to the value obtained by the method described in the example.

[0062] The above zirconium hydroxide powder has a specific surface area of ​​350 m² 2 It is desirable that it be greater than / g. The above specific surface area is 350m² 2 If it is more than / g, it can absorb a larger amount of moisture from the atmosphere.

[0063] The above specific surface area is more preferably 360 m² 2 / g or more, and more preferably 370m 2 / g or more, particularly preferably 380m2 It is greater than / g. While a larger specific surface area is preferable, for example, 500m 2 / g or less, 450m 2 / g is less than or equal to etc.

[0064] The above specific surface area refers to the value obtained by the method described in the example.

[0065] It is preferable that the above zirconium hydroxide powder has an absorption rate of 20% or more as obtained by the following absorption rate measurement method. If the absorption rate is 20% or more, it can be said that it has sufficient absorption capabilities.

[0066] In addition, the above zirconium hydroxide powder does not generate heat upon absorption. In this specification, "no heat generation upon absorption" means that when 10g of zirconium hydroxide powder is added to 100g of water at room temperature (25℃), the temperature rise is 1℃ or less.

[0067] Method for Measuring Absorption Rate

[0068] 1. Weigh the zirconium hydroxide powder.

[0069] 2. The zirconium hydroxide powder after weighing is exposed to an atmosphere of 45°C and 80% humidity for 2 hours.

[0070] 3. The absorption rate is calculated using the following formula (1).

[0071] Equation (1):

[0072] [Absorption Rate (%)] = [[(Weight of Zirconium Hydroxide Powder After Exposure) - (Weight of Zirconium Hydroxide Powder Before Exposure)] / (Weight of Zirconium Hydroxide Powder Before Exposure)] × 100

[0073] The above absorption rate is more preferably 23% or higher, and even more preferably 25% or higher. The higher the above absorption rate, the better, but, for example, 50% or less, 40% or less, etc.

[0074] Zirconium hydroxide is a compound represented by the general formula ZrO(OH)2·nH2O(n>0). Additionally, zirconium hydroxide is a compound represented by the general formula ZrO2·nH2O(n>0). The zirconium hydroxide powder according to the present embodiment comprises both the powder of zirconium hydroxide and the powder of zirconium hydroxide.

[0075] The above n is preferably 2 or less, and more preferably 1.5 or less. If n is 2 or less, it is superior in that it has less moisture and higher hygroscopicity. In addition, because it has less moisture, it has excellent handling properties. The number of n can be adjusted, for example, by the temperature or time of the second drying process described later.

[0076] It is preferable that the above zirconium hydroxide powder be amorphous. When the zirconium hydroxide powder is amorphous, the amount of hydroxyl groups present on the surface of the powder particles increases compared to when it is crystalline. Consequently, moisture becomes more easily adsorbed onto these hydroxyl groups. As a result, the hygroscopicity is superior when the zirconium hydroxide powder is amorphous.

[0077] Whether zirconium hydroxide powder is crystalline or amorphous is determined by X-ray diffraction measurement of the powder. When zirconium hydroxide powder is crystalline, a clear diffraction peak is observed in the range of 2θ=28° to 31°, but when it is amorphous, the peak in that range is broad, and the crystallite diameter calculated from the full width at half maximum is 3 nm or less.

[0078] The use of the above zirconium hydroxide powder is not particularly limited, but, for example, it can be used as a hygroscopic agent either alone or mixed with other materials.

[0079] [Method for manufacturing zirconium hydroxide powder]

[0080] Hereinafter, an example of a method for manufacturing zirconium hydroxide powder is described. However, the method for manufacturing zirconium hydroxide powder according to the present invention is not limited to the following example.

[0081] The method for manufacturing zirconium hydroxide powder according to the present embodiment is

[0082] The method includes a first drying process for drying a wet cake of zirconium hydroxide produced by a wet method until the solid content concentration becomes 60 mass% or more and 87 mass% or less, and

[0083] The drying conditions in the first drying process above are drying conditions in which the rate of increase in solid content concentration is within the range of 5 mass% / h or more and 120 mass% / h or less.

[0084] <1st Drying Process>

[0085] In the method for manufacturing zirconium hydroxide powder according to the present embodiment, first, a wet cake of zirconium hydroxide produced by a wet method is dried until the solid content concentration is 60 mass% or more and 87 mass% or less (first drying process).

[0086] The drying conditions in the first drying process above are drying conditions such that the rate of increase in solid content concentration is within the range of 5 mass% / h or more and 120 mass% / h or less.

[0087] The rate of increase in the above solid content concentration refers to the value obtained by the following formula (2).

[0088] Formula (2):

[0089] [Rate of increase in solid content concentration (mass% / h)] = [[Solid content concentration of zirconium hydroxide powder after first drying (mass%)] - [Solid content concentration of zirconium hydroxide powder before drying (mass%)]] / [Drying time (h)]

[0090] By adopting relatively mild conditions as the drying conditions in the first drying process, that is, drying conditions in which the rate of increase of solid content is within the range of 120 mass% / h or less, the cohesive force is reduced when water in the secondary particles of zirconium hydroxide in the wet cake state evaporates, so the places where water was present are not crushed and remain as holes. As a result, a large number of pores of 1 nm or more and 5 nm or less are formed.

[0091] The drying conditions in the first drying process above can be adjusted by appropriately selecting a drying method or a drying temperature.

[0092] The drying temperature in the first drying process is preferably 360°C or lower, and more preferably 350°C or lower. By setting the drying temperature to 360°C or lower, the rate of increase in solid content concentration can be prevented from exceeding 120 mass% / h. In addition, by setting the drying temperature to 360°C or lower, it is easy to make the obtained zirconium hydroxide powder amorphous. If the drying temperature is too high, the obtained zirconium hydroxide powder is likely to become crystalline. From the perspective of productivity, the drying temperature in the first drying process is preferably 150°C or higher, and more preferably 200°C or higher.

[0093] Examples of the above drying methods include using a shelf dryer or using an air-flow dryer. When using a shelf dryer, the drying speed is slower compared to using an air-flow dryer, so it is easy to adjust the drying speed so that the rate of increase in solid content concentration does not exceed 120 mass% / h. In addition, when using an air-flow dryer, the drying speed is faster compared to using a shelf dryer, so high productivity can be maintained even at a low drying temperature.

[0094] As described above, the first drying process is a process of drying a wet cake of zirconium hydroxide produced by a wet method until the solid content concentration is 60 mass% or more and 87 mass% or less, and the drying conditions in the first drying process are drying conditions in which the rate of increase of the solid content concentration is within the range of 5 mass% / h or more and 120 mass% / h or less. As the drying conditions in the first drying process, the rate of increase of the solid content concentration is preferably 10 mass% / h or more and 100 mass% / h or less, more preferably 20 mass% / h or more and 90 mass% / h or less, even more preferably 30 mass% / h or more and 90 mass% / h or less, particularly preferably 40 mass% / h or more and 80 mass% / h or less, and especially preferably 60 mass% / h or more and 75 mass% / h or less.

[0095] Pores ranging from 1 nm to 5 nm can be formed by appropriately adjusting drying conditions at a low solid content concentration. That is, pores ranging from 1 nm to 5 nm are suitably formed by appropriately adjusting drying conditions between 60 mass% and 87 mass%.

[0096] The first drying process is preferably performed until the solid content concentration of the wet cake reaches 60 mass% or more, and more preferably until it reaches 65 mass% or more. The first drying process is preferably performed until the solid content concentration of the wet cake reaches 87 mass% or less, and more preferably until it reaches 85 mass% or less.

[0097] The starting materials for producing the above-mentioned zirconium hydroxide wet cake are not particularly limited, but it is preferable to use basic zirconium sulfate as a starting material because it facilitates the control of the particle aggregation pattern. The above-mentioned zirconium hydroxide wet cake can be obtained by adding a base using basic zirconium sulfate as a starting material.

[0098] The above basic zirconium sulfate can be obtained by hydrolyzing an aqueous solution of a soluble zirconium salt.

[0099] The above-mentioned soluble zirconium salt is not particularly limited as long as it is soluble in water, and may be obtained by known methods or commercially available products. For example, nitrates such as zirconium oxynitrate, zirconium chloride, chlorides such as zirconium oxychloride, and acetates such as zirconium acetate may be used. Among these, zirconium oxychloride is preferred.

[0100] The concentration of the aqueous solution of soluble zirconium salt can be appropriately set according to the type (solubility) of the soluble zirconium salt used, but it should be about 10 to 200 g, preferably 50 to 100 g, of zirconium oxide in 1 liter of aqueous solution.

[0101] As a hydrolyzing agent, for example, inorganic acids such as sulfuric acid, ammonium sulfate, aluminum sulfate, etc., inorganic salts may be used. The amount of hydrolyzing agent added can be appropriately changed depending on the type of hydrolyzing agent used and the type of aqueous solution, but generally, it is sufficient if it is an amount sufficient to react with all soluble zirconium salts in the aqueous solution to form a slurry, and an excess amount of hydrolyzing agent beyond the stoichiometric amount may be added. The hydrolyzing agent may remain within a range that does not significantly reduce the specific surface area of ​​zirconium hydroxide.

[0102] The type of base mentioned above is not particularly limited, and for example, sodium hydroxide, potassium hydroxide, ammonia, sodium carbonate, ammonium carbonate, etc., can be used. The amount of base added is not particularly limited as long as it can produce a hydroxide, but usually, it is sufficient to adjust the slurry pH to 9 or higher, preferably 12.5 or higher.

[0103] <2nd Drying Process>

[0104] After the first drying process above, it is preferable to dry the wet cake until the solid content concentration exceeds 87 mass% and is 92 mass% or less (second drying process). By performing the second drying process, the final moisture content of the zirconium hydroxide powder can be adjusted to a solid content concentration exceeding 87 mass% and 92 mass% or less. By adjusting the solid content concentration to exceed 87 mass% and 92 mass% or less, the amount of crystal water contained in the zirconium hydroxide powder can be reduced, thereby making it possible to produce a zirconium hydroxide powder with less moisture and higher hygroscopicity.

[0105] The drying conditions in the second drying process above are not particularly limited as long as they are conditions that can adjust the final moisture content of the zirconium hydroxide powder to a solid content concentration of more than 87 mass% and less than or equal to 92 mass%.

[0106] The drying temperature in the second drying process is preferably 200°C or lower, and more preferably 150°C or lower. By setting the drying temperature to 200°C or lower, the zirconium hydroxide powder obtained is likely to be amorphous. If the drying temperature is too high, the zirconium hydroxide powder obtained is likely to be crystalline. From the perspective of productivity, the drying temperature in the second drying process is preferably 100°C or higher, and more preferably 110°C or higher.

[0107] Examples of the above drying methods include using a shelf-type dryer or using an air-flow type dryer.

[0108] The above describes the method for manufacturing zirconium hydroxide powder according to the present embodiment.

[0109] Example

[0110] The present invention will be described in detail below using examples, but the present invention is not limited to the following examples as long as it does not exceed the gist thereof. In addition, the zirconium hydroxide powder obtained in the examples and comparative examples contains 1.3 to 2.5 mass% of hafnium oxide relative to zirconium oxide as an unavoidable impurity (calculated by the following formula (X)).

[0111] <Food(X)>

[0112] ([Mass of Hafnium Oxide] / ([Mass of Zirconium Oxide] + [Mass of Hafnium Oxide])) × 100 (%)

[0113] The maximum and minimum values ​​of the content of each component shown in the following examples should be considered as the preferred minimum and maximum values ​​of the present invention, regardless of the content of other components.

[0114] In addition, the maximum and minimum values ​​of the measurements shown in the following examples should be considered as the preferred minimum and maximum values ​​of the present invention, regardless of the content (composition) of each component.

[0115] [Production of Zirconium Hydroxide Powder]

[0116] (Example 1)

[0117] Basic zirconium sulfate (containing 1 kg as zirconium oxide) was dispersed in 10 kg of pure water to form a basic zirconium sulfate slurry. A 25 mass% aqueous sodium hydroxide solution was added to this slurry until the pH of the slurry reached 13.5 to obtain a precipitate. The resulting precipitate was then separated into solid and liquid phases and washed with water to recover the wet cake of zirconium hydroxide. The solid content concentration in this wet cake was 31.9 mass%.

[0118] Next, the obtained wet cake was dried using a shelf dryer at 350°C for 0.5 hours to obtain zirconium hydroxide powder with a solid content concentration of 68.5 mass%. This drying corresponds to the first drying process in the present invention. The rate of increase in solid content concentration in this first drying process was 73.2 mass% / h.

[0119] Next, the zirconium hydroxide powder according to the present embodiment was obtained by drying at 120°C using a shelf dryer until a constant weight was achieved. This drying corresponds to the second drying process in the present invention. The solid content concentration of the obtained zirconium hydroxide powder was 89.1 mass%.

[0120] In addition, the chemical formula of the obtained zirconium hydroxide powder was ZrO2·0.45H2O, and it was amorphous.

[0121] The chemical formula of the obtained zirconium hydroxide powder was determined by the weight loss rate from room temperature to 200°C in thermogravimetric measurements. In addition, it was confirmed by powder X-ray diffraction measurements that the obtained zirconium hydroxide powder is amorphous.

[0122] (Example 2)

[0123] A wet cake of zirconium hydroxide was obtained in the same way as in Example 1.

[0124] Next, the obtained wet cake was dried using a shelf dryer at 200°C for 2 hours to obtain zirconium hydroxide powder with a solid content concentration of 72.5 mass%. This drying corresponds to the first drying process in the present invention. The rate of increase in solid content concentration in this first drying process was 20.3 mass% / h.

[0125] Next, the zirconium hydroxide powder according to the present embodiment was obtained by drying at 120°C using a shelf dryer until a constant weight was achieved. This drying corresponds to the second drying process in the present invention. The solid content concentration of the obtained zirconium hydroxide powder was 89.5 mass%.

[0126] In addition, the chemical formula of the obtained zirconium hydroxide powder was ZrO2·0.44H2O, and it was amorphous.

[0127] (Example 3)

[0128] A wet cake of zirconium hydroxide was obtained in the same manner as in Example 1, except that the base was changed from a 25 mass% aqueous sodium hydroxide solution to a 25 mass% aqueous ammonia solution. The solid content concentration in this wet cake was 29.3 mass%. Next, the obtained wet cake was dried using a shelf dryer at 250°C for 1.2 hours to obtain zirconium hydroxide powder with a solid content concentration of 73.4 mass%. This drying corresponds to the first drying process in the present invention. The rate of increase in solid content concentration in this first drying process was 36.8 mass% / h.

[0129] Next, the zirconium hydroxide powder according to the present embodiment was obtained by drying at 160°C using a shelf dryer until a constant weight was achieved. This drying corresponds to the second drying process in the present invention. The solid content concentration of the obtained zirconium hydroxide powder was 91.4 mass%.

[0130] In addition, the chemical formula of the obtained zirconium hydroxide powder was ZrO2·0.42H2O, and it was amorphous.

[0131] (Example 4)

[0132] A wet cake of zirconium hydroxide was obtained in the same manner as in Example 1, except that the base was changed from a 25 mass% aqueous sodium hydroxide solution to a 25 mass% aqueous potassium hydroxide solution. The solid content concentration in this wet cake was 29.8 mass%. Next, the obtained wet cake was dried using a shelf dryer at 250°C for 1.2 hours to obtain zirconium hydroxide powder with a solid content concentration of 71.5 mass%. This drying corresponds to the first drying process in the present invention. The rate of increase in solid content concentration in this first drying process was 34.8 mass% / h.

[0133] Next, the zirconium hydroxide powder according to the present embodiment was obtained by drying at 140°C using a shelf dryer until a constant weight was achieved. This drying corresponds to the second drying process in the present invention. The solid content concentration of the obtained zirconium hydroxide powder was 90.4 mass%.

[0134] In addition, the chemical formula of the obtained zirconium hydroxide powder was ZrO2·0.43H2O, and it was amorphous.

[0135] (Comparative Example 1)

[0136] A wet cake of zirconium hydroxide was obtained in the same way as in Example 1.

[0137] Next, the obtained wet cake was dried using an air-dryer at 300°C for 0.3 hours to obtain zirconium hydroxide powder with a solid content of 72.8 mass%. The rate of increase in solid content during this drying process was 136.3 mass% / h.

[0138] Next, the zirconium hydroxide powder according to the comparative example was obtained by drying at 120°C using a shelf dryer until a constant weight was achieved. The solid content concentration of the obtained zirconium hydroxide powder was 89.0 mass%.

[0139] In addition, the chemical formula of the obtained zirconium hydroxide powder was ZrO2·0.42H2O, and it was amorphous.

[0140] (Comparative Example 2)

[0141] A wet cake of zirconium hydroxide was obtained in the same way as in Example 1.

[0142] Next, the obtained wet cake was dried using an air-dryer at 350°C for 0.18 hours to obtain zirconium hydroxide powder with a solid content of 86.6 mass%. The rate of increase in solid content during this drying process was 298.4 mass% / h.

[0143] Next, the zirconium hydroxide powder according to the comparative example was obtained by drying at 120°C using a shelf dryer until a constant weight was achieved. The solid content concentration of the obtained zirconium hydroxide powder was 89.8 mass%.

[0144] In addition, the chemical formula of the obtained zirconium hydroxide powder was ZrO2·0.41H2O, and it was amorphous.

[0145] [Measurement of Solid Content Concentration]

[0146] The weight of the zirconium hydroxide powder of the example and comparative example was measured. After measuring, the zirconium hydroxide powder was calcined at 1000°C for 1 hour, and then the solid content concentration was calculated using the following formula (3).

[0147] Equation (3):

[0148] [Solid content concentration (%)] = [(Weight of zirconium hydroxide powder after calcination) / (Weight of zirconium hydroxide powder before calcination)] × 100

[0149] [Measurement of Crafting Volume]

[0150] The pore distribution of the zirconium hydroxide powder of the example and comparative example was obtained by the BJH method using the measuring device “BELSORP mini II (Microtrac BEL product)”. Figure 1 shows the pore distribution of the zirconium hydroxide powder of the example and comparative example.

[0151] Using the obtained pore distribution, the pore diameter at the peak of the log-differential pore volume, and the pore volume (Vp1) in the pore diameter region between 1 nm and 5 nm. -5 ), pore volume (Vp1) in the pore diameter region of 1 nm to 50 nm -50 ), pore volume of the total pore diameter area (Vp all ), and the average pore diameter was calculated. Also, the ratio (Vp1 -5 / Vp1 - 50 ) was calculated. The results are shown in Table 1.

[0152] [Measurement of Apparent Density]

[0153] For the zirconium hydroxide powders of the examples and comparative examples, the apparent density of the zirconium hydroxide powder was determined from the weight of the zirconium hydroxide powder filled in a volume of 30 ml in accordance with JIS K 5101. The results are shown in Table 1.

[0154] [Measurement of Specific Surface Area]

[0155] The specific surface area of ​​the zirconium hydroxide powders of the examples and comparative examples was measured by the BET method using a specific surface area meter ("Maxov" Mountech product). The results are shown in Table 1.

[0156] [Measurement of Absorption Rate]

[0157] The weight of the zirconium hydroxide powder of the example and comparative example was measured. Next, the weighed zirconium hydroxide powder was exposed to an atmosphere of 45°C and 80% humidity for 2 hours using a constant temperature and humidity chamber. Afterward, the absorption rate was calculated using the following formula (1). The results are shown in Table 1.

[0158] Equation (1):

[0159] [Absorption Rate (%)] = [[(Weight of Zirconium Hydroxide Powder After Exposure) - (Weight of Zirconium Hydroxide Powder Before Exposure)] / (Weight of Zirconium Hydroxide Powder Before Exposure)] × 100

[0160]

Claims

Claim 1 In a pore distribution based on the BJH method, it has a peak top in the pore diameter region of 1 nm or more and 5 nm or less, and the pore volume in the pore diameter region of 1 nm or more and 5 nm or less is 0.15 cm³ 3 Zirconium hydroxide powder characterized by having a g or more and an average pore diameter of 3 nm or more and 6 nm or less. Claim 2 In claim 1, the pore volume in the pore diameter region of 1 nm or more and 5 nm or less is 0.2 cm 3 Zirconium hydroxide powder characterized by having a content of 1g or more. Claim 3 In claim 1 or claim 2, the apparent density is 0.10 g / cm³ 3 Above 0.25g / cm² 3 Zirconium hydroxide powder characterized by the following: Claim 4 In claim 1 or claim 2, the specific surface area is 350 m² 2 Zirconium hydroxide powder characterized by having a content of 1g or more. Claim 5 A method for manufacturing zirconium hydroxide powder as described in claim 1 or claim 2, comprising a first drying process for drying a wet cake of zirconium hydroxide produced by a wet method until the solid content concentration is 60 mass% or more and 87 mass% or less, wherein the drying conditions in the first drying process are drying conditions such that the rate of increase of the solid content concentration is within the range of 5 mass% / h or more and 120 mass% / h or less. Claim 6 A method for manufacturing zirconium hydroxide powder according to claim 5, characterized by including a second drying process after the first drying process, wherein the wet cake is dried until the solid content concentration is greater than 87 mass% and less than or equal to 92 mass%.

Images