JP2005350309A - Manufacturing method of yttoria sol - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of manufacturing an yttoria sol showing a long term stability. <P>SOLUTION: This manufacturing method of yttoria is a method of manufacturing yttoria by a reaction of yttorium hydroxide and hydrogen peroxide, and contains (1) a first process in which a product, yttorium hydroxide coordinated with a peroxo ion on its Y<SP>3+</SP>, is obtained by a reaction of yttorium hydroxide and hydrogen peroxide, and (2) a second process in which an yttoria sol is obtained by further reacting hydrogen peroxide to the product obtained in the first process. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a method for producing yttria sol.

  Yttria sol has been conventionally used as a binder used in manufacturing various refractory materials, casting molds and the like. Further, by applying a liquid containing yttria sol to an object and performing various treatments on the obtained coating film, the object can be imparted with water repellency or good lubricity. For this reason, yttria sol has recently been used for automobile windshields, exterior walls of buildings, and the like.

In Patent Document 1, an yttria sol produced by reacting an aqueous solution of yttrium acetate with an alkaline substance is washed with an ultrafiltration membrane and then concentrated, whereby the particle concentration in the sol is Y ₂ O _3. And a method for producing a transparent yttria sol containing 15 to 35% by weight and particles having an average particle size of 10 to 80% in the sol.

  In Patent Document 2, yttrium hydroxide or holmium and yttrium hydroxide or holmium by spray drying a colloidal dispersion mainly composed of an anion of a monovalent acid having a pKa of 2.5 to 5.0. A process for producing a solid compound which is mainly composed of an anion of a monovalent acid having a pKa of 2.5 to 5.0 and which can be redispersed in water in a proportion of at least 80% and mainly in the form of a colloidal dispersion Is described.

  Patent Document 3 discloses an aqueous solution or a metal salt mixture of a metal salt selected from the group consisting of aluminum compounds, titanium compounds, zirconium compounds, hafnium compounds, niobium compounds, tantalum compounds, yttrium compounds, lanthanum compounds, actinide compounds, and lanthanide compounds. A method is described in which a solution is hydrolyzed by direct electrolysis at -20 to 50 ° C. to produce a single component or multicomponent metal oxide sol.

  However, the yttria sols and the like described in Patent Documents 1 to 3 are inferior in stability over time, so that they are difficult to put into practical use, and there is room for improvement in this respect.

  On the other hand, Patent Document 4 discloses a step of adding a basic solution to a solution containing a metal salt to form a metal hydroxide precipitate, and separating the metal hydroxide precipitate obtained in the above step from the solution. A step of dispersing the separated metal hydroxide in hydrogen peroxide water, heat-treating the resulting solution, and fine particles of metal oxide and / or metal peroxide by the heat treatment. And a process for producing the fine particle-dispersed sol comprising:

However, Patent Document 4 describes that the metal salt used can be applied not only to zinc, aluminum, and niobium but also to metals such as tin, nickel, copper, cobalt, calcium, magnesium, and barium. However, there is no description of rare earth metals including yttrium.
JP-A-5-155616 JP-A-8-319114 JP-A-5-222562 JP2003-26422A

  Accordingly, a main object of the present invention is to provide a method for producing yttria sol that exhibits long-term stability over time.

  As a result of intensive studies in view of the problems of the prior art, the present inventor has found that the above object can be achieved by producing yttria sol by a specific process, and has completed the present invention.

  That is, the present invention relates to the following yttria sol production method.

1. In a method for producing yttria sol by reacting yttrium hydroxide with hydrogen peroxide,
(B) a first step of obtaining a product in which a peroxo ion is coordinated to Y ³⁺ of the yttrium hydroxide by reacting yttrium hydroxide with hydrogen peroxide; and (b) obtained in the first step. A method for producing yttria sol, comprising a second step of obtaining yttria sol by further reacting the product with hydrogen peroxide.

  2. Item 2. The method according to Item 1, wherein the first step is performed at a temperature of 70 ° C or higher and lower than 80 ° C.

  3. Item 2. The method according to Item 1, wherein the second step is performed at a temperature of 80 ° C or higher and 90 ° C or lower.

4). Item 2. The method according to Item 1, wherein in the first step, hydrogen peroxide is reacted with yttrium hydroxide at a molar ratio of H ₂ O ₂ / Y ₂ O ₃ = 1.5 to 2.5.

5). Item 2. The production method according to Item 1, wherein in the second step, hydrogen peroxide is reacted with yttrium hydroxide at a molar ratio of H ₂ O ₂ / Y ₂ O ₃ = 1.0 to 3.0.

  Since the production method of the present invention has two specific steps, an yttria sol having excellent dispersibility over a long period of time can be obtained simply and reliably. In the production method of the present invention, nanoscale fine particles can be obtained depending on the production conditions. For example, it is possible to produce yttria sol having a center diameter (D50) of 20 nm or less (particularly 10 to 20 nm).

  The use of the yttria sol obtained in the present invention is not limited and can be appropriately selected according to various purposes. For example, in addition to binders (binders) used in manufacturing various refractory materials and casting molds, they can also be used as coating agents for windows, automobile windshields, exterior walls of buildings, and the like.

The method for producing yttria sol of the present invention is a method for producing yttria sol by reacting yttrium hydroxide and hydrogen peroxide.
(B) a first step of obtaining a product in which a peroxo ion is coordinated to Y ³⁺ of the yttrium hydroxide by reacting yttrium hydroxide with hydrogen peroxide; and (b) obtained in the first step. The method further includes a second step of obtaining yttria sol by further reacting the product with hydrogen peroxide.
(1) First Step In the first step, peroxy ion (peroxide ion) O ₂ ^2- is coordinated to Y ³⁺ of yttrium hydroxide by reacting yttrium hydroxide with hydrogen peroxide. Get things.

Known or commercially available yttrium hydroxide and yttrium hydrogen peroxide can be used. Moreover, what is obtained by a well-known manufacturing method can also be used.

  In the present invention, yttrium hydroxide obtained by adding an alkali to an yttrium ion-containing aqueous solution can also be suitably used. More specifically, a precipitate obtained by adding an alkali to an aqueous solution obtained by dissolving an yttrium salt in water can be used.

  In this case, the yttrium salt is not particularly limited as long as it is water-soluble, and nitrates, sulfates, acetates, halides (chlorides, bromides, etc.) and the like can be used. More specifically, yttrium nitrate, yttrium sulfate, yttrium acetate, yttrium chloride, and the like can be used. Among these, nitrates and the like are preferable in that impurities are less likely to be mixed in later steps.

  As water used for dissolving the yttrium salt, tap water, distilled water, pure water, or the like can be used, but it is preferable to use distilled water or pure water because there are few impurities.

The concentration of yttrium in the yttrium ion-containing aqueous solution may be about 1 to 10 g / L, preferably about _{2 to 8} g / L, particularly preferably about ₃ to 5 g / L as the Y ₂ O ₃ concentration. When the concentration of the yttrium salt is less than 1 g / L, the production efficiency of yttrium hydroxide may be deteriorated. If it exceeds 10 g / L, the precipitation and filterability of yttrium hydroxide produced by neutralization is not good, and thus impurities in yttrium hydroxide may increase.

  The alkali is not particularly limited as long as it can neutralize an aqueous yttrium salt solution. For example, ammonia, sodium carbonate, sodium hydrogen carbonate, potassium carbonate, potassium hydrogen carbonate, ammonium carbonate, ammonium hydrogen carbonate, sodium hydroxide, calcium hydroxide, barium hydroxide, potassium hydroxide and the like can be used. Among these, it is preferable to use ammonia in that the impurities remaining in yttrium hydroxide are reduced.

  The form of the alkali is not particularly limited, and may be used as a powder or as a solution. Among these, it is preferable to use as a solution, and an aqueous solution is preferable as the solution.

  The concentration when using alkali as an aqueous solution is not limited as long as a precipitate can be formed from an aqueous solution containing yttrium ions. For example, it may be about 20 to 30% by weight.

  By dissolving an yttrium salt in water, an acidic yttrium ion-containing aqueous solution is usually obtained. This aqueous solution can be neutralized by adding alkali thereto. By this neutralization, yttrium hydroxide precipitates.

  The amount of alkali added is not limited, but it is desirable that the pH after neutralization is about 8.6 to 9.5. When the pH is less than 8.6, the ratio of the yttrium salt in the solution to a hydroxide may be low. When pH exceeds 9.5, there exists a possibility of becoming disadvantageous economically.

  This neutralization can be carried out at room temperature. Moreover, neutralization can be performed with stirring as necessary. It is more preferable to carry out neutralization with stirring, since neutralization can be performed efficiently.

  After neutralization is completed, it is preferable to stand for about 10 to 20 hours, for example, to naturally precipitate yttrium hydroxide.

  The yttrium hydroxide thus obtained can be used in the first step as it is, or can be used in the first step after being washed. In terms of removing impurities in yttrium hydroxide, it is preferable to use the first step after washing. For example, after filtration, washing can be performed by adding water. If the supernatant is removed before the filtration, the filtration process can be completed in a short time (efficient filtration can be performed). When washing yttrium hydroxide, the number of times, the amount of pure water to be used, and the like are not limited and can be appropriately selected by those skilled in the art.

  In the present invention, yttrium hydroxide may be used as a solid, but is particularly preferably used as an aqueous dispersion obtained by dispersing yttrium hydroxide in water. For example, an aqueous dispersion obtained by adding water to an yttrium hydroxide-containing wet cake obtained from the yttrium ion-containing aqueous solution can be suitably used.

The concentration of yttrium hydroxide in the case of using an aqueous dispersion is not particularly limited, but is generally 0.1 to 1.0% by weight, particularly 0.5 to 0.6% by weight in terms of Y ₂ O _3. Is desirable.

  In the present invention, a commercially available hydrogen peroxide can be used. In particular, an aqueous solution (hydrogen peroxide solution) obtained by dissolving hydrogen peroxide in water can be preferably used. The concentration in this case is not limited, but is usually about 1 to 10% by weight, particularly 2 to 5% by weight.

Reaction of yttrium hydroxide and hydrogen peroxide By reacting yttrium hydroxide with hydrogen peroxide, a product in which peroxo ion O ₂ ^2- (peroxide ion) is coordinated to Y ³⁺ of yttrium hydroxide. Get.

  For both reactions, yttrium hydroxide and hydrogen peroxide may be mixed. For example, hydrogen peroxide solution may be added to an aqueous dispersion obtained by dispersing yttrium hydroxide in water and mixed with stirring.

The blending ratio of yttrium hydroxide and hydrogen peroxide may be set so that the peroxo ion can be coordinated to Y ³⁺ of yttrium hydroxide, but particularly H ₂ O ₂ / Y ₂ O ₃ = 1 in terms of molar ratio. It is desirable to adjust so that it may become 5-2.5. If H ₂ O ₂ / Y ₂ O ₃ is less than 1.5, the peroxo ion may not be sufficiently coordinated with the yttrium atom of yttrium hydroxide. When H ₂ O ₂ / Y ₂ O ₃ (molar ratio) exceeds 2.5, H ₂ O ₂ may remain in the generated sol.

Although the reaction temperature in the first step is not limited, it is usually desirable that the reaction temperature be 70 ° C. or higher and lower than 80 ° C. When the reaction temperature is less than 70 ° C., it may take a long time to coordinate the peroxo ion to Y ³⁺ . When the reaction temperature is 80 ° C. or higher, the yttria sol is generated simultaneously by the coordination of peroxo ions and the release of hydrogen ions, making it difficult to control the reaction and making it impossible to produce yttria sols with uniform quality characteristics. There is a fear.

The reaction time can be appropriately determined depending on the reaction temperature or the like, but generally it is preferably 0.5 to 2 hours, particularly 1 to 1.5 hours.
(2) Second Step In the second step, yttria sol is obtained by further reacting the product obtained in the first step with hydrogen peroxide.

In the second step, yttria sol is produced mainly by the following mechanism by adding hydrogen peroxide to the product. That is, by adding hydrogen peroxide, a product in which a peroxo ion is coordinated to Y ³⁺ of yttrium hydroxide is peptized, and a hydrogen ion is released from the product, thereby generating an yttria sol. Thereby, it is possible to obtain a yttria sol having excellent temporal stability with good reproducibility.

  As the hydrogen peroxide, the same hydrogen peroxide as that used in the first step can be used. Hydrogen peroxide is preferably added as it is to the product (reaction system) obtained in the first step.

The blending ratio of the product and hydrogen peroxide may be set so that the above-described effect occurs, but usually the molar ratio is H ₂ O ₂ / Y ₂ O ₃ = 1.0 to 3.0, particularly 1 It is desirable to adjust so that it may become 5-2.5. When H ₂ O ₂ / Y ₂ O ₃ is less than 1.0, sufficient production of yttria sol is achieved by peptization of the product in which peroxo ions are coordinated to Y ³⁺ of yttrium hydroxide and release of hydrogen ions. There is a risk that it will not be possible. Also, if the _{H 2 O 2 / Y 2 O} 3 (the molar ratio) exceeds 3.0, H ₂ O ₂ in the resulting sol may remain.

Although the reaction temperature in the second step is not limited, it is generally desirable that the reaction temperature is 80 ° C. or higher and 90 ° C. or lower. When the reaction temperature is less than 80 ° C., the reaction rate may be slow. When the reaction temperature exceeds 90 ° C., the reaction of hydrogen peroxide itself proceeds to oxidize the product in which the peroxo ion is coordinated to Y ³⁺ of yttrium hydroxide, thereby generating a sol having a large particle size. The dispersibility may be reduced.

  Moreover, although reaction time can be suitably determined by reaction temperature etc., generally it is desirable to set it as 5 to 10 hours.

The reaction in the second step is basically almost completed when the reaction solution becomes uniform and translucent from the suspended state. This change can be confirmed visually. After cooling the reaction solution to room temperature, the yttria sol may be recovered according to a known solid-liquid separation method such as filtration, centrifugation, or ultrafiltration. In this case, the yttria sol can be recovered in a form containing the liquid phase of the reaction solution. For example, after filtering the reaction solution, ultrafiltration can be performed to obtain a dispersion having a concentration (Y ₂ O ₃ conversion) of 5% by weight or less.

The yttria sol obtained by the production method of the present invention generally has a particle size in the range of 10 to 100 nm. Further, the center diameter D ₅₀ is preferably 20nm or less (in particular: 10 to 20 nm). Moreover, the yttria sol obtained in the present invention is excellent in long-term stability. For example, even after storage for 3 months, the yttria sol does not gel (aggregates) and can maintain a good dispersed state.

  Examples are given below to further clarify the features of the present invention. In addition, this invention is not limited to the range of these Examples.

Example 1
Pure water was added to 100 g of an aqueous yttrium nitrate solution (containing 15.13 g as Y ₂ O ₃ ) to make 4 L. The pH at this time was 1.96. This was neutralized by adding 65.51 g of a 25% aqueous ammonia solution to produce yttrium hydroxide. The pH at this time was 9.23. The solution was allowed to stand for 12 hours, and then the supernatant was removed and filtered. Thereafter, washing with 200 ml of pure water was performed 5 times to remove impurities in the yttrium hydroxide to obtain 259.17 g of a wet cake.

100 g of this wet cake was put into a beaker, and pure water was added to make 1 L. This was stirred for 15 minutes to uniformly disperse yttrium hydroxide. To this was added a solution of 5.0 g of 35% hydrogen peroxide solution in 50 ml of water (H ₂ O ₂ / Y ₂ O ₃ molar ratio = 2.0), and then heated to 75 ° C. for 1 hour. By stirring and holding, the peroxo ion was sufficiently coordinated to the yttrium atom in the yttrium hydroxide.

Next, a solution of 5.0 g of 35% hydrogen peroxide solution in 50 ml of water was added to this solution (H ₂ O ₂ / Y ₂ O ₃ molar ratio = 2.0), and then heated to 85 ° C. Then, by stirring and holding for 7 hours, the yttrium atom in yttrium hydroxide coordinated with a peroxo ion was peptized and hydrogen ions were released to produce an yttria sol. The obtained solution was translucent and was confirmed to be completely yttria sol by visual observation.

Then, after cooling to room temperature, it filtered with the filter paper (pore diameter: 1 micrometer) and the membrane filter (pore diameter: 1.0 micrometer). Then, a membrane filter (pore diameter: 0.025 .mu.m) was concentrated by ultrafiltration with, (as Y ₂ O _3, from about 5.8g containing) yttria sol 177.74g was obtained.

The particle size distribution of the obtained yttria sol is shown in FIG. This shows that an yttria sol having a particle size of about 10 to 80 nm and a center diameter (D ₅₀ ) of about 15 nm can be obtained.

Example 2
When 100 g of the yttria sol obtained in Example 1 was stored at room temperature for 3 months and the state of the sol was observed, no gelation was observed and it was confirmed that the yttria sol was stable.

2 is a graph showing the particle size distribution of yttria sol obtained in Example 1. FIG.

Claims (5)

In a method for producing yttria sol by reacting yttrium hydroxide with hydrogen peroxide,
(B) a first step of obtaining a product in which a peroxo ion is coordinated to Y ³⁺ of the yttrium hydroxide by reacting yttrium hydroxide with hydrogen peroxide; and (b) obtained in the first step. A method for producing yttria sol, comprising a second step of obtaining yttria sol by further reacting the product with hydrogen peroxide. The manufacturing method according to claim 1, wherein the first step is performed at a temperature of 70 ° C or higher and lower than 80 ° C. The manufacturing method according to claim 1, wherein the second step is performed at a temperature of 80 ° C. or higher and 90 ° C. or lower. 2. The method according to claim 1, wherein in the first step, hydrogen peroxide is reacted with yttrium hydroxide at a molar ratio of H ₂ O ₂ / Y ₂ O ₃ = 1.5 to 2.5. 2. The production method according to claim 1, wherein in the second step, hydrogen peroxide is reacted with yttrium hydroxide at a molar ratio of H ₂ O ₂ / Y ₂ O ₃ = 1.0 to 3.0.

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