TW202019816A - Method for producing aqueous dispersion and organic solvent dispersion of zirconium oxide particles - Google Patents

Abstract

An objective of the present invention is to provide a method for obtaining a zirconium oxide particles aqueous dispersion, which has a chlorine ion content with respect to the weight of zirconium particles in the range of 1500 to 7000 ppm, and has excellent transparency and low viscosity as well as, in particular, excellent storage stability over a long period of time regardless of the environmental temperature even if it contains fine zirconium oxide particles at a high concentration.

According to the present invention, a method for producing a zirconium oxide particles aqueous dispersion is provided, the method including the following steps: reacting zirconium oxychloride with a basic substance to obtain a 1st water slurry containing zirconium oxide particles; washing the 1st water slurry with water to obtain a 2nd water slurry, and adding 1 mol part or more of an organic acid to 1 mol part of zirconium in the 2nd water slurry to obtain a 3rd water slurry having a chlorine ion content of less than 4000 ppm with respect to the weight of zirconium particles, next, adding hydrochloric acid to the 3rd water slurry to obtain a 4th water slurry having a chlorine ion content with respect to the weight of the zirconium oxide particles in the range of 4000 to 20000ppm; hydrothermally treating the 4th water slurry to obtain a zirconium oxide particles aqueous dispersion precursor; and washing the zirconium oxide particles aqueous dispersion precursor by ultrafiltration to obtain a zirconium oxide particles aqueous dispersion having a chloride ion content with respect to the weight of the zirconium oxide particles in the range of 1500 to 7000 ppm.

Description

Method for producing aqueous dispersion of zirconia particles and organic solvent dispersion

The present invention relates to a method for producing an aqueous dispersion of zirconia particles and an organic solvent dispersion. Specifically, the present invention relates to low viscosity and high transparency while containing fine zirconia particles in a high concentration. In addition, each method for producing an aqueous dispersion liquid and an organic solvent dispersion liquid of zirconia particles having excellent long-term storage stability. The zirconia particle dispersion obtained according to the method of the present invention can be used in various applications in the optical field, and is particularly useful as a material for optical composite resins such as LED sealing resins and anti-reflection films.

Conventionally, inorganic oxide particle dispersions such as silicon oxide, aluminum oxide, zinc oxide, tin oxide, zirconium oxide, and titanium oxide have been used in various industrial fields, especially in the optical field, for adjusting the refractive index. In particular, since zirconia has a high refractive index, in recent years, various proposals have been made to utilize highly functional resins and films that are compounded with transparent resins and films and whose refractive index is increased.

For example, it is known that by adding zirconia with a high refractive index to the sealing resin covering the LED, the refractive index of the sealing resin can be increased and the light emitted from the luminous body can be taken out more efficiently And the LED brightness is increased.

Similarly, zirconia is also used as an anti-reflection film on the display surface of flat panel displays (FPD) such as liquid crystal displays (LCD) and electroluminescence displays (EL). The antireflection film is a laminated film formed by laminating a low refractive index layer and a high refractive index layer, and a composite resin material in which zirconia is dispersed is used for the high refractive index layer.

In the above applications, when the primary particle size of zirconia and the secondary aggregate particle size in the resin are not sufficiently smaller than the wavelength of visible light (380 to 800 nm), due to the influence of scattering caused by the zirconia particles, the seal The resin and the anti-reflection film are turbid, so that the necessary transparency cannot be obtained. Therefore, there is a strong demand for the development of a highly transparent zirconia particle dispersion liquid in which zirconia particles are dispersed in resin as fine particles.

In order to meet such requirements, various methods of obtaining zirconia fine particles and their dispersions have been proposed in recent years. As a representative method for obtaining a dispersion liquid of zirconia particles, it is known to use zirconium hydroxide produced by alkali neutralization of zirconium salt, for example, adding hydrochloric acid to a slurry of zirconium hydroxide at a predetermined concentration and boiling A method of heating at a temperature to obtain a zirconia particle dispersion liquid (see Patent Document 1). However, according to this method, since the average particle diameter of the obtained zirconia is 50 nm or more, it is difficult for the dispersion liquid to have sufficient transparency.

It is also known that an aqueous solution containing a zirconium salt is added to an aqueous solution of an alkali metal hydroxide heated to 60° C. or more, and after neutralization, that is, after reverse neutralization, filtration, washing, and addition of water and stirring Then, a method of adding an acid and heating and stirring at a temperature of 80 to 100°C to obtain a zirconia dispersion liquid (see Patent Document 2).

Also, a method is known in which a zirconium hydroxide gel is obtained by neutralizing a zirconium salt in the presence of carboxylic acids such as malic acid, citric acid, tartaric acid, and the like in water, and temporarily washing it After purification, a method of aging and fully dispersing by ultrasonic irradiation or the like, and then performing hydrothermal treatment in the presence of the carboxylic acid again to obtain a zirconia particle dispersion liquid (refer to Patent Document 3).

A method is also proposed in which a zirconium salt is reacted with an alkali in water to obtain a slurry of zirconium oxide particles. Secondly, the slurry is filtered, washed, and repulped, and in the resulting slurry, After adding 1 mole part or more of organic acid and hydrothermal treatment at a temperature of 170° C. or more with respect to 1 mole part of zirconium in the slurry, the obtained aqueous dispersion of zirconia particles is washed to obtain high Method for transparent aqueous dispersion of zirconia particles (see Patent Document 4).

While the use of zirconia particle dispersions has expanded, their usage has also increased, and as a result, the requirements for their long-term storage stability have increased, but the above-mentioned conventional zirconia particle dispersions have no record of long-term storage stability, and according to The obtained aqueous dispersion may actually have poor long-term storage stability.

It has been proposed to add stabilizers such as acetic acid, β-diketone, and salicylic acid to an aqueous dispersion of zirconia particles, and filter to replace water with an organic solvent, resulting in excellent stability over time. Organic solvent dispersion (see Patent Document 5), but it is not clear to what extent it has stability over time.

In particular, regarding long-term storage stability, since the dispersion liquid of zirconia nanoparticles known in the past has insufficient long-term storage stability, in order to ensure long-term storage stability or prevent deterioration, storage at a refrigerated temperature or a frozen temperature is usually carried out And return to normal temperature when using.

[Prior Technical Literature] [Patent Literature]

[Patent Document 1] Japanese Patent Laid-Open No. 5-24844

[Patent Document 2] Japanese Patent Laid-Open No. 2008-31023

[Patent Document 3] Japanese Patent Laid-Open No. 2006-143535

[Patent Document 4] Japanese Patent Application Publication No. 2010-150066

[Patent Document 5] Japanese Patent Laid-Open No. 2007-238422

The present invention was made to solve the above-mentioned problems of the conventional zirconia particle dispersion liquid, and the object of the present invention is to provide a method for manufacturing each of the aqueous dispersion liquid of the zirconia particle and the organic solvent dispersion liquid, even at a high concentration The particles containing fine zirconia also have excellent transparency and low viscosity, and in particular, have excellent storage stability over a long period of time.

In particular, the object of the present invention is to provide excellent long-term storage stability even in an environment where the temperature in the range of about 10°C to about 40°C is not controlled, regardless of the temperature, and therefore even in an environment of normal temperature Production methods of aqueous dispersions and organic solvent dispersions of zirconia nanoparticles with excellent long-term storage stability.

The present inventors started from the step of reacting zirconium oxychloride with an alkaline substance in alkaline water to obtain a first aqueous slurry containing zirconia particles, and guiding it to an aqueous dispersion and The method of organic solvent dispersion was studied in detail, and it was found that the second and third water slurries of zirconia particles starting from the first water slurries and obtained on the way (and according to the situation will provide The precursor of the aqueous dispersion) relative to the weight of the zirconia particles, the chloride ion content rate is controlled to be the most suitable, and finally the above The chloride ion content is set to a predetermined range, whereby an aqueous dispersion of zirconia particles and an organic solvent dispersion can be obtained. Even if the fine zirconia particles are contained in a high concentration, they have excellent transparency and low viscosity, and In particular, in terms of the above-mentioned meaning, it has excellent storage stability over a long period of time, and the present invention has been completed.

According to the present invention, it is possible to provide each of the following methods for producing an aqueous dispersion of zirconia particles and an organic solvent dispersion. Furthermore, according to the present invention, it is possible to provide a method for producing each of the aqueous dispersion of the stabilized zirconia particles containing the solid solution of the stabilized element and the organic solvent dispersion in the same manner.

(1) Production of aqueous dispersion of zirconia particles

A method for manufacturing an aqueous dispersion of zirconia particles includes the following steps:

The first step is to react zirconium oxychloride with basic substances in water to obtain a first water slurry containing zirconia particles and having a pH in the range of 9.6 to 11.0;

The second step is to carry out the following (a) or (b),

(a) After filtering and washing the first water slurry, re-slurry in water to obtain a second water slurry containing the zirconium oxide particles. In the second water slurry, the amount For the parts of ears, 1 molar part or more of organic acid is added, and a third water slurry having a chloride ion content rate of less than 4000 ppm relative to the weight of the zirconia particles is obtained, followed by addition to the third water slurry Hydrochloric acid to obtain a fourth aqueous slurry having a chloride ion content rate in the range of 4000 to 20000 ppm with respect to the weight of the zirconia particles,

(b) After filtering and washing the first water slurry, re-slurry in water to obtain a second water slurry containing the zirconia particles, and add hydrochloric acid to the second water slurry to obtain The third aqueous slurry having a chloride ion content rate in the range of 4000 to 20,000 ppm with respect to the weight of the zirconia particles, followed by adding the organic acid 1 to 1 mole of zirconium in the third aqueous slurry Molar parts or more, and a fourth aqueous slurry having a chloride ion content rate in the range of 4000 to 20000 ppm relative to the weight of the zirconia particles is obtained;

The third step is to hydrothermally treat the fourth aqueous slurry to obtain the precursor of the aqueous dispersion of zirconia particles; and

The fourth step is to wash the zirconia particle aqueous dispersion precursor by ultrafiltration to obtain zirconia particle water having a chloride ion content rate in the range of 1500 to 7000 ppm relative to the weight of the zirconia particle Dispersions.

(2) Manufacture of water dispersion of stabilized zirconia particles

A method for manufacturing an aqueous dispersion of stabilized zirconia particles includes the following steps:

The first step is to react zirconium oxychloride with at least one stabilizing element salt selected from aluminum, magnesium, titanium and rare earth elements in water to react with an alkaline substance to obtain a co-precipitate containing zirconium and the above stabilizing element Particles and the first water slurry with a pH in the range of 9.6 to 11.0;

The second step is to carry out the following (a) or (b),

(a) After filtering and washing the first water slurry, re-slurry in water to obtain a second water slurry containing particles of the co-precipitate of the zirconium and the stabilizing element, and in the second water In the slurry, 1 mole part or more of organic acid is added to 1 mole part of the total amount of zirconium and the stabilizer element, and the total weight converted to the oxide of zirconium and the stabilizer element is obtained. The third water slurry having a chloride ion content of less than 4000 ppm, and then adding hydrochloric acid to the third water slurry to obtain the chloride ion content relative to the total weight of zirconium and the oxide of the stabilizing element converted The fourth water slurry in the range of 4000 to 20000ppm,

(b) After filtering and washing the first water slurry, re-slurry in water to obtain a second water slurry containing particles of the co-precipitate of the zirconium and the stabilizing element, and in the second water Hydrochloric acid is added to the slurry to obtain a third aqueous slurry having a chloride ion content rate in the range of 4000 to 20000 ppm based on the total weight of zirconium and the oxide of the stabilizer element, followed by the third aqueous slurry In which, 1 mole part or more of an organic acid is added to 1 mole part of the total amount of zirconium and the above-mentioned stabilizer element, and the chloride ion is obtained with respect to the total weight converted to the oxide of zirconium and the above stabilizer element. The fourth water slurry with a content rate in the range of 4000 to 20000 ppm;

The third step is to hydrothermally treat the fourth water slurry to obtain a stabilized zirconia particle aqueous dispersion precursor containing a solid solution of the stabilized element; and

The fourth step is to wash the precursor of the stabilized zirconia particle aqueous dispersion by ultrafiltration to obtain a chloride ion content rate in the range of 1500 to 7000 ppm relative to the weight of the stabilized zirconia particle Stabilized aqueous dispersion of zirconia particles.

(3) Production of organic solvent dispersion of zirconia particles

A method for producing an organic solvent dispersion of zirconia particles, in which the dispersion medium of the aqueous dispersion of zirconia particles obtained according to the method described in (1) above, that is, water is replaced with an organic solvent to obtain zirconia. In terms of the weight of the particles, the chloride ion content rate is in the range of 1500 to 7000 ppm and the dispersion medium is the above-mentioned organic solvent zirconia particle organic solvent dispersion.

(4) Manufacturing of organic solvent dispersion of stabilized zirconia particles

A method for producing an organic solvent dispersion of stabilized zirconia particles is to replace the dispersion medium of the aqueous dispersion of stabilized zirconia particles obtained according to the method described in (2) above, namely water By changing to an organic solvent, a stabilized zirconia particle organic solvent dispersion liquid having a chloride ion content rate in the range of 1500 to 7000 ppm with respect to the weight of stabilized zirconia particles and a dispersion medium of the above organic solvent is obtained.

Hereinafter, (stabilized) zirconia particle system means zirconia particles and/or stabilized zirconia particles.

As described above, both the (stabilized) zirconia particle aqueous dispersion and the organic solvent dispersion obtained according to the method of the present invention have high transparency even if they contain fine (stabilized) zirconia particles at a high concentration. And low viscosity, the viscosity increase is less than 20mPa‧s when stored at 25℃ for 24 months, and the long-term storage stability is significantly excellent.

According to the preferred aspect of the present invention, the viscosity can be obtained regardless of the ambient temperature, especially even if it is kept under normal temperature environment for more than 40 months, the viscosity and the viscosity immediately after manufacturing are substantially unchanged, and have very excellent long-term storage Stable (stabilized) aqueous dispersion of zirconia particles and organic solvent dispersion.

(1) Manufacturing method of aqueous dispersion of zirconia particles

Step 1

In the production of an aqueous dispersion of zirconia particles according to the method of the present invention, the first step is to react zirconium oxychloride with an alkaline substance in water to obtain first water containing the zirconia particles and having a pH in the range of 9.6 to 11.0 Slurry.

In the present invention, the temperature range when zirconium oxychloride is reacted with the above-mentioned alkaline substance in water is not particularly limited, but it is usually in the range of 10 to 50°C, preferably in the range of 15 to 40°C.

In the neutralization reaction when neutralizing zirconium oxychloride, which is an acid, with an alkaline substance, the molar excess of the alkaline substance relative to the acid, that is, the molar excess of alkali neutralization It is usually in the range of 1.15 to 1.5. The molar excess of the above-mentioned basic substance with respect to acid is mentioned later.

For a method of reacting zirconium oxychloride with the above-mentioned alkaline substance in water, for example, a method of adding an alkaline substance aqueous solution to a zirconium oxychloride salt aqueous solution; a method of adding a zirconium oxychloride aqueous solution to an alkaline substance aqueous solution ; And the method of simultaneously adding the zirconium oxychloride salt solution and the alkaline substance aqueous solution to the so-called pre-filled liquid that has been put in the precipitation reactor in advance; although any method can be used, the oxychlorination The zirconium aqueous solution and the alkaline substance are simultaneously added to the so-called pre-filled liquid that has been put in the reaction vessel in advance, and the neutralization method is preferable.

As the alkaline substance, alkali metal hydroxides such as sodium hydroxide and potassium hydroxide, ammonia, etc. can be preferably used, but they are not limited by these examples. The above alkaline substance is usually used as an aqueous solution.

The concentration of the zirconium oxychloride aqueous solution is preferably 2.4 mol/L or less, and the concentration of the above alkaline substance aqueous solution is preferably 10 mol/L or less.

According to the present invention, in this way, the first aqueous slurry having a zirconia particle concentration of 1 to 20% by weight is usually obtained in the first step. When the concentration of zirconia particles in the first water slurry is greater than 20% by weight, the viscosity of the first water slurry is high and it is difficult to stir, and the content of chloride ions of the obtained zirconia particles becomes non-uniform. The washing in step 2 becomes insufficient, and due to With such an aqueous slurry, an aqueous dispersion of zirconia particles having targeted high transparency and low viscosity cannot be obtained. In particular, according to the present invention, the zirconia particle concentration of the first aqueous slurry is preferably in the range of 1 to 10% by weight.

Step 2

In the present invention, the second step is to filter and wash the first aqueous slurry obtained in the first step, and then re-slurry in water to obtain a second aqueous slurry containing the zirconia particles. 2 The organic acid and hydrochloric acid are added to the water slurry to obtain a water slurry containing zirconia particles (fourth water slurry) having a chloride ion content rate in the range of 4000 to 20000 ppm relative to the weight of the zirconia particles. step.

In the second step, regarding the order of adding the above-mentioned organic acid and hydrochloric acid, the following method (a) of adding an organic acid first may be used, or the following method (b) of adding hydrochloric acid first may be used.

Method (a) is as follows.

(a) After filtering and washing the first water slurry, re-slurry in water to obtain a second water slurry containing the zirconium oxide particles. In the second water slurry, the amount For the parts of ears, 1 molar part or more of organic acid is added, and a third water slurry having a chloride ion content rate of less than 4000 ppm relative to the weight of the zirconia particles is obtained, followed by addition to the third water slurry Hydrochloric acid is used to obtain a fourth aqueous slurry having a chloride ion content rate in the range of 4,000 to 20,000 ppm relative to the weight of the zirconia particles.

Method (b) is as follows.

(b) After filtering and washing the first water slurry, re-slurry in water to obtain a second water slurry containing the zirconia particles, and add hydrochloric acid to the second water slurry to obtain In terms of the weight of the zirconia particles, the chloride ion content rate is in the range of 4,000 to 20,000 ppm In the third water slurry, secondly, in the above third water slurry, 1 mole part or more of organic acid is added to 1 mole part of zirconium to obtain chloride ion relative to the weight of zirconia particles. The fourth water slurry having a content rate in the range of 4,000 to 20,000 ppm.

According to the above method (a), by adding 1 mole part or more of organic acid to 1 mole part of zirconium in the second water slurry, chlorine is obtained with respect to the weight of the zirconium oxide particles The third water slurry having an ion content of 3000 ppm or less is preferable, and it is particularly preferable to obtain the third water slurry having 2000 ppm or less.

In the first step, when the zirconium oxychloride and the basic substance are reacted in water to obtain a first aqueous slurry containing zirconia particles, the use of the basic substance relative to the zirconium oxychloride When the amount is large and the pH during the above reaction is higher than the above range, the amount of the alkaline substance absorbed inside the obtained zirconia particles increases, and the above alkaline substance cannot be completely removed in the second step, so in the third step The hydrochloric acid added in is neutralized and consumed during the hydrothermal treatment in the fourth step. As a result, an aqueous dispersion of zirconia particles having a target chloride ion content cannot be obtained.

On the other hand, in the aforementioned first step, when the zirconium oxychloride and the alkaline substance are reacted in water to obtain a first aqueous slurry containing zirconia particles, the alkali When the amount of the substance used is small and the pH during the above reaction is lower than the above range, it becomes difficult to control the content rate of the chloride ion absorbed inside the obtained zirconia particles. As a result, the chlorine in each reaction The degree of unevenness of the ion content is large, and it is impossible to obtain an aqueous dispersion of zirconia particles with a stable chloride ion content.

After the first water slurry is filtered and washed with water, and then re-slurryed in water to obtain a second water slurry containing zirconia particles, the second water slurry is 500 μS/cm The following conductivity is preferred.

When zirconium oxychloride is neutralized with alkaline substances such as potassium hydroxide in water, potassium chloride is produced by-product. Therefore, when potassium chloride that is the by-product salt contained in the first aqueous slurry obtained by reacting zirconium oxychloride with potassium hydroxide in water is not sufficiently removed, even if an organic acid is added to this It is difficult to obtain a sufficient dispersion effect in the aqueous slurry and hydrothermal treatment. Therefore, even if ultrafiltration treatment is performed thereafter, a highly transparent aqueous dispersion of zirconia particles cannot be obtained.

In addition, in the present invention, when the obtained first water slurry is filtered and washed, and the obtained filter cake is re-slurried in water to be used as the second water slurry, the filter cake may be added to The water is stirred by a stirrer to form a water slurry. However, the above-mentioned filter cake can be repulped in water by means of wet medium dispersion such as a bead mill, ultrasonic irradiation, high-pressure homogenizer, etc., if necessary.

As described above, in the second step, organic acid and hydrochloric acid are added to the second water slurry to obtain zirconia particle-containing water having a chloride ion content rate within a predetermined range with respect to the weight of the zirconia particles. Slurry, but in this case, hydrochloric acid also functions as a degumming agent, and the above organic acid is a degumming agent in the same way as hydrochloric acid (chloride ion), and is used to make the zirconia particles in the obtained third water slurry It is used by so-called acid gelation dispersed by mutual charge repulsion.

The organic acid is preferably a carboxylic acid or hydroxycarboxylic acid. Specific examples of such organic acids include, for example, monocarboxylic acids such as formic acid, acetic acid, and propionic acid; dicarboxylic acids such as oxalic acid, malonic acid, succinic acid, fumaric acid, and maleic acid; And higher polybasic acids; salts of hydroxycarboxylic acids such as lactic acid, malic acid, tartaric acid, citric acid, gluconic acid, etc.

In addition, these organic acids are as described above with respect to the third water to be hydrothermally treated The 1 molar part of zirconium in the slurry can usually be used in the range of 1 molar part or more, preferably in the range of 1 to 5 molar parts, and most preferably in the range of 1 to 3 molar parts. When the amount of organic acid is less than 1 mol part relative to 1 mol part of zirconium in the third water slurry, the obtained aqueous dispersion of zirconia particles may not only have insufficient transparency but also increase in viscosity. On the other hand, even if the amount of organic acid is more than 5 mol parts relative to 1 mol part of zirconium in the third water slurry, there is no particularly commensurate effect and economic efficiency.

The hydrochloric acid is not particularly limited, but it is preferably a concentration of 40% or less.

Step 3

According to the present invention, in the third step, the fourth aqueous slurry containing the aforementioned organic acid and having a chloride ion content rate in the range of 4000 to 20000 ppm relative to the weight of the zirconia particles is 170°C or higher A hydrothermal treatment was performed at a temperature of 500 °C to obtain a precursor of an aqueous dispersion of zirconia particles.

As mentioned above, the organic acid is a degumming agent. According to the present invention, the fourth water slurry is treated in the presence of the degumming agent under severe conditions that will become hydrothermal treatment, so the zirconia particles are more Effectively degumming.

According to the present invention, the concentration of zirconia particles for the fourth water slurry subjected to the heat treatment for water supply is usually in the range of 1 to 20% by weight, preferably in the range of 1 to 10% by weight. When the concentration of zirconia particles in the fourth water slurry is greater than 20% by weight, the viscosity of the water slurry is high and it is difficult to perform hydrothermal treatment. In particular, according to the present invention, the concentration of zirconia particles in the fourth water slurry is preferably in the range of 1 to 10% by weight.

The temperature of the hydrothermal treatment is usually 170°C or higher, preferably 170°C to 230°C. When the temperature of the hydrothermal treatment is lower than 170°C, the obtained zirconia particles are dispersed in water The liquid may not only not have sufficient transparency, but also contain coarse aggregated particles with a settling property and have a high viscosity.

The time of the hydrothermal treatment is usually 1 hour or more, preferably 3 hours or more. When the hydrothermal treatment time is shorter than 1 hour, the obtained aqueous dispersion of zirconia particles not only does not have sufficient transparency, but also generates sedimentary coarse aggregated particles, and the target high-transparency zirconia particle water cannot be obtained Dispersions. The time for hydrothermal treatment can be increased regardless of how long it is, but since it is not possible to obtain a particularly commensurate effect, usually 10 hours or less is sufficient.

Step 4

Next, according to the present invention, the precursor of the aqueous dispersion of zirconia particles thus obtained as the fourth step is washed by ultrafiltration to obtain a chloride ion content rate relative to the weight of the zirconia particles An aqueous dispersion of zirconia particles in the range of 1500 to 7000 ppm (preferably 2000 to 5000 ppm) and the concentration of zirconia particles is usually in the range of 1 to 30% by weight. When the chloride ion concentration is less than 1500 ppm with respect to the weight of the zirconia particles, the storage stability of the aqueous dispersion deteriorates. On the other hand, if the chloride ion concentration is greater than 7000 ppm with respect to the weight of the zirconia particles, there is a risk of corrosion of manufacturing equipment.

According to the present invention, the aqueous dispersion of zirconia particles thus obtained can be concentrated as necessary. For this concentration, it can be carried out by means such as evaporative concentration by a rotary evaporator, concentration by ultrafiltration using an ultrafiltration membrane, or the like. The concentration method is not particularly limited, but it is preferably concentrated by ultrafiltration using an ultrafiltration membrane.

Therefore, according to the present invention, the aqueous dispersion of zirconia particles obtained by the hydrothermal treatment can be washed while being concentrated using an ultrafiltration membrane. That is, the aqueous dispersion of zirconia particles is ultrafiltered and concentrated, and water is added to the resulting concentrated liquid to dilute, Washing and ultrafiltration of the obtained water slurry again, the ultrafiltration of the aqueous dispersion is performed and the concentration and dilution are repeated, whereby the aqueous dispersion of zirconia particles obtained by hydrothermal treatment is concentrated At the same time, washing is performed, and the residual by-product salts are repeatedly removed together with water. In this way, the aqueous dispersion of zirconia particles is concentrated, and an aqueous dispersion having an increased zirconia concentration can be obtained.

According to the present invention, by doing so, an aqueous dispersion of zirconia particles having a zirconia particle concentration of 10 to 50% by weight, low viscosity and high transparency, and excellent long-term storage stability can be obtained.

According to the present invention, the upper limit of the concentration of zirconia particles in the aqueous dispersion of zirconia particles is usually 50% by weight, preferably 40% by weight. This is because the aqueous dispersion having a zirconia particle concentration greater than 50% by weight has a high viscosity, and will eventually lose fluidity and gel.

Next, the stabilized zirconia particle aqueous dispersion produced by the method of the present invention and containing a solid solution of a stabilized element will be described.

(2) Manufacture of water dispersion of stabilized zirconia particles

According to the first method of the method of the present invention, in order to obtain an aqueous dispersion of stabilized zirconia particles, in the method of producing the aqueous dispersion of zirconia particles, an aqueous solution containing zirconium oxychloride and a salt of the stabilized element is used Instead of the aqueous solution of zirconium oxychloride, the same treatment may be performed. The concentration of the above-mentioned stabilizer element salt in the above-mentioned aqueous solution is usually preferably 0.5 mol/L or less.

In the present invention, the stabilizing element is preferably at least one selected from aluminum, magnesium, titanium, and rare earth elements.

The salt system of the above-mentioned stabilizer element is not particularly limited, but usually can be suitably used Water-soluble salts such as chlorides and nitrates. For example, when the stabilizer element is aluminum, aluminum chloride can be suitably used, and when the stabilizer element is yttrium, yttrium chloride can be suitably used. In the present invention, the above-mentioned stabilizer element is usually used in the range of 1 to 20 mol% relative to the zirconium element.

In the present invention, for example, in the neutralization reaction when the acidic zirconium oxychloride and yttrium chloride are neutralized using an alkaline substance, the molar excess of the alkaline substance relative to the acid is usually The range of 1.15 to 1.5 is preferred. The molar excess of the above-mentioned basic substance with respect to acid is mentioned later.

According to the present invention, in order to obtain an aqueous dispersion of zirconia particles containing a solid solution of the above-mentioned stabilizing element, it is the same as the case of obtaining the above-mentioned aqueous dispersion of zirconia particles. First, the first step is to oxychlorinate Zirconium and the salt of the stabilizer element react with an alkaline substance in water to obtain a first aqueous slurry containing particles of the coprecipitate of the zirconium and the stabilizer element and having a pH in the range of 9.6 to 11.0.

Next, the second step is to perform the following (a) or (b),

(a) After filtering and washing the first water slurry, re-slurry in water to obtain a second water slurry containing particles of the co-precipitate of the zirconium and the stabilizing element, and in the second water In the slurry, 1 mole part or more of organic acid is added to 1 mole part of the total amount of zirconium and the stabilizer element, and the total weight converted to the oxide of zirconium and the stabilizer element is obtained. The third water slurry having a chloride ion content of less than 4000 ppm, and then adding hydrochloric acid to the third water slurry to obtain the chloride ion content relative to the total weight of zirconium and the oxide of the stabilizing element converted The fourth water slurry in the range of 4000 to 20000ppm;

(b) After filtering and washing the first water slurry, re-slurry in water to obtain a second water slurry containing particles of the co-precipitate of the zirconium and the stabilizing element, and in the second water Hydrochloric acid is added to the slurry to obtain a third water slurry having a chloride ion content rate in the range of 4000 to 20000 ppm based on the total weight of zirconium and the oxide of the stabilizer element, followed by the third water slurry In which, 1 mole part or more of an organic acid is added to 1 mole part of the total amount of zirconium and the above-mentioned stabilizer element, and the chloride ion is obtained with respect to the total weight converted to the oxide of zirconium and the above stabilizer element. The fourth water slurry having a content rate in the range of 4,000 to 20,000 ppm.

Next, as in the case of obtaining an aqueous dispersion of zirconia particles, the third step is to hydrothermally treat the fourth aqueous slurry to obtain a stabilized zirconia particle aqueous dispersion precursor; the fourth step is to The above precursor is washed by ultrafiltration to obtain a chloride ion content rate in the range of 1500 to 7000 ppm (preferably 2000 to 5000 ppm) relative to the weight of stabilized zirconia particles, and the concentration of zirconia particles The aqueous dispersion of stabilized zirconia particles is usually in the range of 1 to 30% by weight.

The stabilized zirconia particle aqueous dispersion obtained in accordance with the method of the present invention also has the same characteristics as the aforementioned zirconia particle aqueous dispersion.

That is, regarding the (stabilized) zirconia particle aqueous dispersion obtained according to the method of the present invention, when the (stabilized) zirconia particle concentration is 30% by weight, the total light transmittance is 70% or more. In the particle size distribution measurement by the dynamic light scattering method, the 50% volume particle size based on the volume basis, that is, the D50 is 1 to 20 nm, preferably 1 to 10 nm, and the viscosity at the temperature of 25°C immediately after manufacturing is 20mPa‧s or less, preferably 10mPa‧s or less, compared with the viscosity at a temperature of 25°C immediately after manufacture, the increase in viscosity at a temperature of 25°C after 24 months after manufacture is 20mPa‧s or less, preferably Below 10mPa‧s

According to a preferred aspect of the method of the present invention, according to the present invention (stabilization) oxidation The aqueous dispersion of zirconium particles can be obtained regardless of the ambient temperature, especially after being stored for 40 months or longer in an environment other than the refrigeration and freezing temperatures below 10°C and normal temperature for a long period of time. The latter is an aqueous dispersion of stabilized zirconia particles that does not change substantially.

Next, the organic solvent dispersion liquid of zirconia particles produced (stabilized) according to the method of the present invention will be described.

(3) (Stabilization) Production of organic solvent dispersion of zirconia particles

According to the method of the present invention, as described above, the aqueous dispersion of zirconia particles is obtained (stabilized) through the first to fourth steps.

Therefore, according to the present invention, by replacing water, which is a dispersion medium of the above-mentioned (stabilized) zirconia particle aqueous dispersion, with an organic solvent, it is possible to obtain the organic solvent as a dispersion medium and to achieve the above-mentioned (stabilized) In terms of the weight of the zirconia particles, an organic solvent dispersion liquid of (stabilized) zirconia particles having a chloride ion content rate in the range of 1500 to 7000 ppm (preferably 2000 to 5000 ppm).

In the present invention, the organic solvent system is not particularly limited, but it is preferably a water-miscible organic solvent. The water-miscible organic solvent system is not particularly limited, but for example, aliphatic alcohols such as methanol, ethanol, 2-propanol; aliphatic carboxylic acid esters such as ethyl acetate and methyl formate; acetone, methyl ethyl Aliphatic ketones such as ketone and methyl isobutyl ketone; polyhydric alcohols such as ethylene glycol and glycerin; mixtures of two or more of these, particularly preferably methanol, methyl ethyl ketone and methyl isobutyl ketone Or a mixture of these.

According to the present invention, in order to replace the water, which is the dispersion medium in the (stabilized) zirconia particle aqueous dispersion, with an organic solvent, the aqueous dispersion is treated using a rotary evaporator and After removing the water, add a new organic solvent; or ultrafiltration the aqueous dispersion and remove the dispersion medium, that is, water to obtain a slurry, and then add the organic solvent to dilute and ultrafiltration again, so and repeat the filtration And diluting, thereby replacing the original dispersion medium, that is, water, with an organic solvent, and obtaining a (stabilized) zirconia particle organic solvent dispersion with the organic solvent as the dispersion medium.

Furthermore, for example, by replacing the dispersion medium in the (stabilized) zirconia particle aqueous dispersion, that is, water, with a water-miscible organic solvent to obtain (stabilized) zirconia particle organic using the water-miscible organic solvent as the dispersion medium After the solvent dispersion, the water-miscible organic solvent is further replaced with another organic solvent, and a new (stabilized) zirconia particle organic solvent dispersion using the other organic solvent as a dispersion medium can be obtained.

The (stabilized) zirconia particle organic solvent dispersion obtained according to the present invention also has the same characteristics as the aforementioned (stabilized) zirconia particle aqueous dispersion and has a low viscosity, and has high transparency and excellent Long-term preservation of stability.

As described above, the (stabilized) aqueous dispersion of zirconia particles and the organic solvent dispersion obtained according to the method of the present invention can be further dispersed with a wet medium such as a bead mill, ultrasonic irradiation, or high-pressure homogenizer if necessary. Wait for decentralized processing.

When the (stabilized) zirconia particle aqueous dispersion and organic solvent dispersion obtained according to the method of the present invention described above have a (stabilized) zirconia particle concentration of 30% by weight, the total light transmittance is 70% or more. In the particle size distribution measurement by the dynamic light scattering method, the 50% volume particle size based on the volume basis, that is, the D50 is 1 to 20 nm, preferably 1 to 10 nm, and the temperature at 25°C immediately after manufacturing Viscosity is 20mPa‧s or less, preferably 10mPa‧s or less, compared with the viscosity at the temperature of 25℃ immediately after manufacturing, the temperature at 24 months after manufacturing The increase in viscosity at 25°C is 20 mPa‧s or less, preferably 10 mPa‧s or less.

According to a preferred aspect of the method of the present invention, the obtained (stabilized) zirconia particle aqueous dispersion and organic solvent dispersion, even after being stored in a normal temperature environment for a long period of time for more than 40 months, have a viscosity that is Substantially unchanged after manufacturing.

As explained above, according to the method of the present invention, it is possible to obtain excellent long-term storage stability regardless of the ambient temperature, for example, even in an environment where the temperature ranging from about 10°C to about 40°C is not controlled. Even under normal temperature environment, it has excellent long-term storage stability of aqueous dispersion of zirconia nanoparticles and organic solvent dispersion.

Of course, the aqueous dispersion and organic solvent dispersion of zirconia particles according to the present invention are stored at a refrigerated temperature and then returned to normal temperature during use, or stored after freezing and then thawed during use When returning to normal temperature, the physical properties and stability cannot be observed to change or deteriorate.

[Example]

In the following examples and comparative examples, the ultrafiltration in the fourth step was performed using "MICROZA" manufactured by Asahi Kasei Chemicals Co., Ltd., model ACV-3010D (molecular weight cutoff 13000). In the production of organic solvent dispersions, The ultrafiltration when replacing the dispersion medium of the water dispersion liquid, that is, water with an organic solvent, was performed using Asahi Kasei Chemicals Co., Ltd. "MICROZA", model ACP-1010D (molecular weight cutoff 13000).

In addition, in the following examples and comparative examples, the particle size distribution, viscosity, and total light transmittance of (stabilized) zirconia particle dispersion, and the chloride ion concentration of (stabilized) zirconia particle aqueous slurry or dispersion It was measured as follows.

Particle size distribution

D50, D90, and Dmax were measured using a dynamic light scattering method particle size distribution measuring apparatus (UPA-UT manufactured by Nikkiso Co., Ltd.). In addition, D50, D90 and Dmax are values based on volume.

Viscosity

Measured using a tuning fork-type vibrating SV-type viscometer (SV-1A (measured viscosity range 0.3 to 1000 mPa‧s) manufactured by A&D Corporation).

Total light transmittance

Using a haze meter (NDH4000 manufactured by Nippon Denshoku Industries Co., Ltd.), fill ion-exchanged water into a photolysis tube with a light path length of 10 mm and perform standard calibration, and similarly fill the dispersion into the photolysis tube to measure the total light transmission rate. In addition, when the total light transmittance is 50% or more, the dispersion liquid and the dispersion precursor are considered to be transparent.

Chloride ion concentration

Using an automatic titration device (TS-2000 manufactured by Hiranuma Industries Co., Ltd.), silver nitrate was added to the obtained water slurry and dispersion liquid, and chloride ion was measured by precipitation titration.

Evaluation of long-term storage stability of dispersion

Manufacture a dispersion liquid, and evaluate its viscosity increase when stored at 25°C for 24 months as 20 mPa‧s or less (with excellent long-term storage stability). Manufacture a dispersion liquid and store it at a temperature of 25°C When the viscosity increase during storage for 24 months is more than 20mPa‧s, or when it has gelled, it is evaluated as "×" (long-term storage stability is poor).

Example 1

(Manufacture of stabilized zirconia particle aqueous dispersion (I-1))

Step 1

900L of a mixed aqueous solution of 0.6 mol/L zirconium oxychloride and 0.03 mol/L yttrium chloride was prepared. The above mixed aqueous solution of zirconium oxychloride and yttrium chloride was injected into a precipitation reactor pre-loaded with 1500 L of a potassium hydroxide aqueous solution of 0.9 mol/L concentration. Neutralization reaction and co-precipitation to obtain a first aqueous slurry containing particles of co-precipitates of zirconium and yttrium. The pH of the obtained first water slurry was 10.

Step 2

The first water slurry was filtered, washed until the conductivity of the water-washed filtrate became 10 μS/cm or less, and was re-pulped again in pure water to obtain particles containing the co-precipitate of zirconium and yttrium. 2nd water slurry. 42 kg of acetic acid (1.3 mol parts relative to 1 mol part of the total amount of zirconium and yttrium in the second water slurry) was added to the second water slurry to obtain oxidation with zirconium and yttrium Based on the total weight in terms of material conversion, the third water slurry 600L having a solid content rate of 7.5% by weight and a chloride ion concentration of 8 ppm. In the third water slurry, the chloride ion content rate calculated based on the chloride ion concentration relative to the total weight in terms of oxides of zirconium and yttrium is 110 ppm.

Next, 1 kg of 35% hydrochloric acid was added to the third water slurry to obtain a fourth water slurry having a chloride ion concentration of 580 ppm. In the fourth water slurry, the chloride ion content rate calculated based on the chloride ion concentration with respect to the total weight converted to oxides of zirconium and yttrium is 7730 ppm.

Step 3

The fourth water slurry was hydrothermally treated at 190°C for 3 hours to obtain a transparent aqueous dispersion precursor of stabilized zirconia particles.

Step 4

The transparent dispersion liquid precursor of the stabilized zirconia particles was washed and concentrated using an ultrafiltration membrane to obtain a stabilized zirconia particle aqueous dispersion (I -1). In the aqueous dispersion, the chloride ion content rate calculated based on the chloride ion concentration relative to the weight of the stabilized zirconia particles was 2730 ppm.

(Production of the stabilized zirconia particle methanol dispersion liquid (II-1))

10 kg of the above-mentioned stabilized zirconia particle aqueous dispersion (I-1) was concentrated using an ultrafiltration membrane, and methanol in an amount equivalent to the amount of the obtained filtrate was poured into the concentrated dispersion thus obtained, and by continuous At the same time, the dispersion liquid is concentrated and diluted with methanol, while the content of the stabilized zirconia in the dispersion liquid is maintained at 30% by weight, and the dispersion medium of the dispersion liquid is replaced from water to methanol to obtain stability. A stabilized zirconia particle methanol dispersion (II-1) with a zirconia particle concentration of 30.8% by weight and a chloride ion concentration of 810 ppm. At this time, the amount of methanol used for dilution was 90 L.

In the above methanol dispersion of stabilized zirconia particles, the chloride ion content rate calculated based on the chloride ion concentration relative to the weight of the stabilized zirconia particles was 2630 ppm.

Example 2

(Manufacture of stabilized zirconia particle aqueous dispersion (I-2))

Step 1

900 L of a mixed aqueous solution of 0.6 mol/L zirconium oxychloride and 0.03 mol/L of yttrium chloride and 680 L of 1.9 mol/L of potassium hydroxide aqueous solution were prepared. Inject the mixed aqueous solution of zirconium oxychloride and yttrium chloride and the aqueous solution of potassium hydroxide into pure water In the 820L precipitation reactor, zirconium oxychloride and yttrium chloride were co-precipitated by simultaneous neutralization to obtain a first aqueous slurry containing particles of a co-precipitate of zirconium and yttrium. The pH of the obtained first water slurry was 10.2.

Step 2

The first water slurry was filtered, washed until the conductivity of the water-washed filtrate became 10 μS/cm or less, and was re-pulped again in pure water to obtain particles containing the co-precipitate of zirconium and yttrium. 2nd water slurry. 42 kg of acetic acid (1.3 mol parts relative to 1 mol part of the total amount of zirconium and yttrium in the second water slurry) was added to the second water slurry to obtain oxidation with zirconium and yttrium Based on the total weight in terms of substance conversion, 600 L of the third water slurry having a solid content rate of 7.5% by weight.

The chloride ion concentration of the third water slurry is 3 ppm. In the third water slurry, the chloride ion content rate calculated based on the chloride ion concentration relative to the total weight in terms of zirconium and yttrium oxide conversion is 40 ppm.

Next, 130 g of 35% hydrochloric acid was added to 60 L of the third water slurry to obtain a fourth water slurry having a chloride ion concentration of 720 ppm. In the fourth water slurry, the chloride ion content rate calculated based on the chloride ion concentration with respect to the total weight converted to oxides of zirconium and yttrium is 9650 ppm.

Step 3

The fourth water slurry was hydrothermally treated at 190°C for 3 hours to obtain a transparent aqueous dispersion precursor of stabilized zirconia particles.

Step 4

The transparent dispersion precursor of the stabilized zirconia particles was washed and concentrated using an ultrafiltration membrane to obtain a stabilized zirconia particle aqueous dispersion (I of 30.4% by weight of stabilized zirconia particles and a chloride ion concentration of 1010 ppm (I -2). In the aqueous dispersion, the chloride ion content rate calculated based on the chloride ion concentration relative to the weight of the stabilized zirconia particles is 3320 ppm.

Example 3

(Manufacture of stabilized zirconia particle aqueous dispersion (I-3))

Step 2

85 g of 35% hydrochloric acid was added to 60 L of the third water slurry obtained in Example 2 to obtain a fourth water slurry having a chloride ion concentration of 480 ppm. In the fourth water slurry, the chloride ion content rate calculated based on the chloride ion concentration with respect to the total weight in terms of oxides of zirconium and yttrium is 6420 ppm.

Step 3

The fourth water slurry was hydrothermally treated at 190°C for 3 hours to obtain a transparent aqueous dispersion precursor of stabilized zirconia particles.

Step 4

The transparent dispersion liquid precursor of the stabilized zirconia particles was washed and concentrated using an ultrafiltration membrane to obtain a stabilized zirconia particle aqueous dispersion (I of stable zirconia particle concentration 30.4% by weight and chloride ion concentration 670 ppm -3). In the aqueous dispersion, the chloride ion content rate calculated based on the chloride ion concentration relative to the weight of the stabilized zirconia particles was 2210 ppm.

Example 4

(Manufacture of stabilized zirconia particle aqueous dispersion (I-4))

Step 2

65 g of 35% hydrochloric acid was added to 60 L of the third water slurry obtained in Example 2 to obtain a fourth water slurry having a chloride ion concentration of 380 ppm. In the fourth water slurry, the chloride ion content rate calculated based on the chloride ion concentration relative to the total weight in terms of zirconium and yttrium oxide conversion is 5080 ppm.

Step 3

The fourth water slurry was hydrothermally treated at 190°C for 3 hours to obtain a transparent aqueous dispersion precursor of stabilized zirconia particles.

Step 4

The transparent dispersion precursor of the stabilized zirconia particles was washed and concentrated using an ultrafiltration membrane to obtain a stabilized zirconia particle aqueous dispersion (I of 30.0% by weight and a chloride ion concentration of 530 ppm -4). In the aqueous dispersion, the chloride ion content rate calculated based on the chloride ion concentration relative to the weight of the stabilized zirconia particles was 1770 ppm.

Comparative example 1

(As a comparative example, production of stabilized zirconia particle aqueous dispersion (I-5))

Step 2

25 g of 35% hydrochloric acid was added to 60 L of the third water slurry obtained in Example 2 to obtain a fourth water slurry having a chloride ion concentration of 140 ppm. In the fourth water slurry, the chloride ion content rate calculated based on the chloride ion concentration with respect to the total weight converted to the oxide of zirconium and yttrium is 1830 ppm.

Step 3

The fourth water slurry was hydrothermally treated at 190°C for 3 hours to obtain a transparent aqueous dispersion precursor of stabilized zirconia particles.

Step 4

The transparent dispersion liquid precursor of the stabilized zirconia particles was washed and concentrated using an ultrafiltration membrane to obtain a stabilized zirconia particle aqueous dispersion (I -5). In the aqueous dispersion, the chloride ion content rate calculated based on the chloride ion concentration relative to the weight of the stabilized zirconia particles was 640 ppm.

Comparative example 2

(Production of stabilized zirconia particle aqueous dispersion (I-6) as a comparative example)

Step 3

The third aqueous slurry obtained in Example 2 was hydrothermally treated at 190°C for 3 hours to obtain a transparent aqueous dispersion precursor of stabilized zirconia particles.

Step 4

The transparent dispersion precursor of the stabilized zirconia particles was washed and concentrated using an ultrafiltration membrane to obtain a stabilized zirconia particle aqueous dispersion (I -6). In the aqueous dispersion, the chloride ion content rate calculated based on the chloride ion concentration relative to the weight of the stabilized zirconia particles was 10 ppm.

Example 5

(Production of aqueous dispersion of zirconia particles (I-7))

Step 1

900 L of zirconium oxychloride aqueous solution with a concentration of 0.6 mol/L and 680 L of a potassium hydroxide aqueous solution with a concentration of 1.9 mol/L were prepared. The above-mentioned zirconium oxychloride aqueous solution and potassium hydroxide aqueous solution were simultaneously injected into a precipitation reactor pre-loaded with 820 L of pure water, and zirconium oxychloride was precipitated by simultaneous neutralization to obtain first water containing zirconia particles Slurry. The pH of the obtained first water slurry was 10.

Step 2

The above-mentioned first water slurry was filtered, washed until the conductivity of the water-washed filtrate became 10 μS/cm or less, and re-slurryed again in pure water to obtain a second water slurry containing the above-mentioned zirconia particles. 42 kg of acetic acid (1.4 mol parts relative to 1 mol of zirconium in the above-mentioned second water slurry) was added to the above-mentioned second water slurry to obtain a solid content by weight in terms of zirconium oxide 600L of the third water slurry with a rate of 7.5% by weight.

The chloride ion concentration of this third water slurry is 6 ppm. In the third water slurry, the chloride ion content rate calculated based on the chloride ion concentration relative to the weight of the zirconia particles was 90 ppm.

Next, 1.8 kg of 35% hydrochloric acid was added to the third water slurry to obtain a fourth water slurry having a chloride ion concentration of 1040 ppm. In the fourth water slurry, the chloride ion content rate calculated based on the chloride ion concentration relative to the weight of the zirconia particles was 13,800 ppm.

Step 3

The fourth water slurry was hydrothermally treated at 190°C for 3 hours to obtain a transparent aqueous dispersion precursor of stabilized zirconia particles.

Step 4

The transparent aqueous dispersion precursor of the zirconia particles was washed and concentrated using an ultrafiltration membrane to obtain an aqueous dispersion of zirconia particles (I-7) having a zirconia particle concentration of 30.2% by weight and a chloride ion concentration of 1440 ppm. In the aqueous dispersion, the chloride ion content rate calculated based on the chloride ion concentration relative to the weight of the zirconia particles was 4790 ppm.

(Manufacture of zirconia particle methanol dispersion liquid (II-7))

10 kg of the above-mentioned aqueous dispersion of zirconia particles (I-7) was concentrated using an ultrafiltration membrane, and methanol in an amount equivalent to the amount of the obtained filtrate was poured into the concentrated dispersion obtained in this way, and by continuous and simultaneous Concentration of the dispersion liquid and dilution with methanol are performed in parallel, while the concentration of zirconia particles in the dispersion liquid is maintained at 30% by weight, and the dispersion medium of the dispersion liquid is replaced from water to methanol to obtain a zirconia particle concentration of 30.3 A methanol dispersion liquid of zirconia particles (II-7) of 5% by weight and a chloride ion concentration of 1400 ppm. At this time, the amount of methanol used for dilution was 90 L. In the methanol dispersion liquid, the chloride ion content rate calculated based on the chloride ion concentration relative to the weight of the zirconia particles was 4610 ppm.

When methanol was removed from the zirconia particle methanol dispersion obtained in Example 5 above and dried, the zirconia fine particle powder thus obtained was observed by TEM (transmission electron microscope), the average of the zirconia particles was once The particle size is about 5 nm.

Methanol was removed from the stabilized zirconia particle-containing methanol dispersion liquid of the solid solution containing yttrium obtained in Examples 1 to 4 and Comparative Examples 1 and 2, and the stabilized zirconia particle powder thus obtained was borrowed When observed by TEM (transmission electron microscope), the average primary particle diameter of the stabilized zirconia particles is about 3 nm.

In the above examples and comparative examples, when the aqueous solution of (mixed) zirconium oxychloride (with yttrium chloride) (acid) was neutralized with potassium hydroxide (alkali), the molar excess of the alkali relative to the acid was Degree display 示于表1。 Shown in Table 1. Here, the above-mentioned molar excess is expressed by the ratio of the molar amount of the base used in the neutralization reaction/the molar amount of the acid used.

The chemical formula of the neutralization reaction of zirconium oxychloride and yttrium chloride by potassium hydroxide is as follows.

ZrOCl ₂ +2KOH→ZrO(OH) ₂ +2KCl…(1)

YCl ₃ +3KOH→Y(OH) ₃ +3KCl…(2)

Therefore, the molar excess E of the base relative to the acid can be obtained according to the following formula.

E=K/(2Z+3Y)…(3)

Here, K represents the molar amount of potassium hydroxide used, Z represents the molar amount of zirconium oxychloride used, and Y represents the molar amount of yttrium chloride used.

In the above Examples 1 to 5 and Comparative Examples 1 and 2, the concentration of the potassium hydroxide aqueous solution used in the first step, the pH of the first aqueous slurry obtained in the first step, and the second step The chloride ion concentration of the third water slurry obtained in step 3 and the chloride ion content rate (Cl/ZrO ₂ ) calculated from the chloride ion concentration, and the fourth water slurry obtained in the second step (Example 1) Table 5 shows the chloride ion concentration to 5 and Comparative Example 1) and the chloride ion content rate (Cl/ZrO ₂ ) calculated based on the chloride ion concentration. However, the above-mentioned chloride ion content ratio in Examples 1 to 4 and Comparative Examples 1 and 2 is the chloride ion content ratio in terms of the total weight converted to oxides of zirconium and yttrium, and is the relative value in Example 5. The chloride ion content rate in terms of the weight of the zirconia particles.

Furthermore, the (stabilized) zirconia particle concentration, pH, conductivity, particle size distribution, and total light of the (stabilized) zirconia particle aqueous dispersion obtained in Examples 1 to 5 and Comparative Examples 1 and 2 above Transmittance, chloride ion concentration, chloride ion content ratio (Cl/ZrO ₂ ) relative to the weight of (stabilized) zirconia particles calculated based on the chloride ion concentration, the aqueous dispersion immediately after production at 25°C The evaluation results of the viscosity and the long-term storage stability of the aqueous dispersion are shown in Table 2.

Furthermore, the concentration, particle size distribution, total light transmittance, and chloride ion concentration of the methanol dispersion of the zirconia particles obtained in Examples 1 and 5 above, and the calculated relative to ) For the zirconia particles, the chloride ion content (Cl/ZrO ₂ ), moisture content, viscosity at 25°C immediately after production, viscosity 7 days after production, and long-term storage stability evaluation results are shown in Table 3 .

[Table 1]

[Table 2]

[table 3]

The (stabilized) zirconia particle aqueous dispersion obtained according to the method of the present invention, as shown in Examples 1 to 5, even if it contains fine zirconia particles in a high concentration, has high transparency and low viscosity, and The increase in viscosity when stored at 25°C for 24 months is 20mPa‧s or less, which has remarkable long-term storage stability. In particular, when the preferred form is adopted, even if it is stored for more than 40 months, its viscosity at 25° C. is substantially unchanged from immediately after manufacture, and it has very excellent long-term storage stability.

Furthermore, even if the dispersion medium of the aqueous dispersion of (stabilized) zirconia particles obtained according to the method of the present invention, that is, the organic solvent dispersion obtained by replacing water with an organic solvent, as shown in Table 3, is dispersed with water In the same way, even if it contains fine zirconia particles in high concentration, it has high transparency and low viscosity, and the viscosity increase when stored at 25°C for 24 months is 20mPa‧s or less, which has significantly excellent long-term storage Stability. In particular, when the preferred form is adopted, even if it is stored for more than 40 months, its viscosity at 25° C. is substantially unchanged from immediately after manufacture, and it has very excellent long-term storage stability.

Claims (4)

A method for manufacturing an aqueous dispersion of zirconia particles includes the following steps: The first step is to react zirconium oxychloride with basic substances in water to obtain a first water slurry containing zirconia particles and having a pH in the range of 9.6 to 11.0; The second step is to carry out the following (a) or (b), (a) After filtering and washing the first water slurry, re-slurry in water to obtain a second water slurry containing the zirconium oxide particles. In the second water slurry, the amount For the parts of ears, 1 molar part or more of organic acid is added, and a third water slurry having a chloride ion content rate of less than 4000 ppm relative to the weight of the zirconia particles is obtained, followed by addition to the third water slurry Hydrochloric acid to obtain a fourth aqueous slurry having a chloride ion content rate in the range of 4000 to 20000 ppm with respect to the weight of the zirconia particles, (b) After filtering and washing the first water slurry, re-slurry in water to obtain a second water slurry containing the zirconia particles, and add hydrochloric acid to the second water slurry to obtain The third water slurry having a chloride ion content rate in the range of 4000 to 20000 ppm in terms of the weight of the zirconia particles, followed by adding 1 mole of organic acid to 1 mole of zirconium in the third water slurry More than one part to obtain a fourth aqueous slurry having a chloride ion content rate in the range of 4000 to 20000 ppm relative to the weight of the zirconia particles; The third step is to hydrothermally treat the fourth aqueous slurry to obtain the precursor of the aqueous dispersion of zirconia particles; and The fourth step is to wash the zirconia particle aqueous dispersion precursor by ultrafiltration to obtain zirconia particle water having a chloride ion content rate in the range of 1500 to 7000 ppm relative to the weight of the zirconia particle Dispersions. A method for manufacturing an aqueous dispersion of stabilized zirconia particles includes the following steps: The first step is to react zirconium oxychloride with at least one stabilizing element salt selected from aluminum, magnesium, titanium and rare earth elements in water to react with an alkaline substance to obtain a co-precipitate containing zirconium and the above stabilizing element Particles and the first water slurry with a pH in the range of 9.6 to 11.0; The second step is to carry out the following (a) or (b), (a) After filtering and washing the first water slurry, re-slurry in water to obtain a second water slurry containing particles of the co-precipitate of the zirconium and the stabilizing element, and in the second water In the slurry, 1 mole part or more of organic acid is added to 1 mole part of the total amount of zirconium and the stabilizer element, and the total weight converted to the oxide of zirconium and the stabilizer element is obtained. The third water slurry having a chloride ion content of less than 4000 ppm, and then adding hydrochloric acid to the third water slurry to obtain the chloride ion content relative to the total weight of zirconium and the oxide of the stabilizing element converted The fourth water slurry in the range of 4000 to 20000ppm, (b) After filtering and washing the first water slurry, re-slurry in water to obtain a second water slurry containing particles of the co-precipitate of the zirconium and the stabilizing element, and in the second water Hydrochloric acid is added to the slurry to obtain a third aqueous slurry having a chloride ion content rate in the range of 4000 to 20000 ppm based on the total weight of zirconium and the oxide of the stabilizer element, followed by the third aqueous slurry In which, 1 mole part or more of an organic acid is added to 1 mole part of the total amount of zirconium and the above-mentioned stabilizer element, and the chloride ion is obtained with respect to the total weight converted to the oxide of zirconium and the above stabilizer element. The fourth water slurry with a content rate in the range of 4000 to 20000 ppm; The third step is to hydrothermally treat the fourth water slurry to obtain Stabilized zirconia particle aqueous dispersion precursor of solid solution of stabilizing elements; and The fourth step is to wash the precursor of the stabilized zirconia particle aqueous dispersion by ultrafiltration to obtain a chloride ion content rate in the range of 1500 to 7000 ppm relative to the weight of the stabilized zirconia particle Stabilized aqueous dispersion of zirconia particles. A method for producing an organic solvent dispersion of zirconia particles, in which the dispersion medium of the aqueous dispersion of zirconia particles obtained according to the manufacturing method described in item 1 of the patent application range, that is, water is replaced with an organic solvent to obtain a relative The content of chloride ion in the weight of the zirconia particles is in the range of 1500 to 7000 ppm and the dispersion medium is an organic solvent dispersion of zirconia particles of the above organic solvent. A method for manufacturing an organic solvent dispersion of stabilized zirconia particles is to replace the organic solvent of water as the dispersion medium of the aqueous dispersion of stabilized zirconia particles obtained according to the manufacturing method described in item 2 of the scope of patent application, On the other hand, a stabilized zirconia particle organic solvent dispersion liquid having a chloride ion content rate in the range of 1500 to 7000 ppm with respect to the weight of the stabilized zirconia particles and a dispersion medium of the above-mentioned organic solvent is obtained.