JPH01148710A - Crystalline cerium(iv) oxide sol and its production - Google Patents

Abstract

PURPOSE:To produce the title sol having excellent transparency, ultraviolet- absorbing power, dispersibility and coating characteristic by hydrothermally treating the gel obtd. by reacting cerium chloride compd. with alkali metal hydroxide or ammonia. CONSTITUTION:The gel is obtd. by reacting the cerium chloride compd. (e.g., CeCl3) (A) at 10-90 deg.C in an aq. medium with the alkali metal hydroxide (e.g., NaOH) or ammonia (B) in 0.9-1.3 the equiv. ratio B/A of acid radicals originated in (B) and (A) components. Then, the gel is filtered and washed to remove impurities. Thereafter, the gel is added with 0.01-1.00mol acid to 1mol CeO2 in the gel and hydrothermally treated at >=100 deg.C to obtain sol, and the obtd. sol is dried at a temp. below the temp. that the added acid can be evaporated or changed in quality to obtain the crystalline CeO2 sol having <=300Angstrom particle size.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a crystalline ceric oxide sol and a method for producing the same.

Ceric oxide is used in abrasives, catalysts, masking agents for IC substrates, ultraviolet absorbers, decolorizing agents for glass, electron beam absorbers, ceramic dielectrics, and the like. Among these fields of application, the present invention provides an excellent ultraviolet absorbing material that can be applied to ultraviolet absorbing glass, ultraviolet absorbing polymer films, plastics, improving the liquid resistance of synthetic fibers, and the like.

(Prior Art) In recent years, ultraviolet absorbing glasses and films with excellent translucency have been developed. Conventionally, such glass has been produced by melting metal oxides and the like having ultraviolet absorbing ability together with glass components.

A coating method has also been developed in which a metal oxide is deposited on a glass surface by chemical vapor deposition (CVD).

However, as chemical vapor deposition generally uses anhydrous metal chloride as a raw material, corrosive chlorine gas is generated during I1 deposition, and the deposition is performed at high temperatures in a closed furnace, so the deposition gas Control was difficult and it was difficult to obtain a uniform thin film.

Furthermore, the equipment used in this case is large in size and has the disadvantage of increasing manufacturing cost.

In addition, according to the physical vapor deposition method (PVD method) of metal, a thin metal film that absorbs visible light is formed on the glass surface.
The light transmittance of the glass is significantly reduced, resulting in a dark glass with poor light transmittance, which limits the uses of products made by this method.

On the other hand, recently there has been a strong demand for glass for automobiles to have ultraviolet absorbing ability, and surface treatment techniques for large-sized glass are required more than ever, and vapor deposition methods tend to be increasingly difficult and cost-effective.

Therefore, in place of the CVD method or the PVD method, there is a demand for the development of an inexpensive method that can form uniform thin films even on large products.

Furthermore, with regard to films for food packaging, there is currently an increasing demand for harmless alternatives to organic ultraviolet absorbers in order to prevent photooxidative deterioration of plastics caused by ultraviolet rays or deterioration of foods.

(Problems to be Solved by the Invention) In view of these circumstances, the present inventors have developed an ultraviolet ray that has excellent translucency and ultraviolet absorption, and also has excellent properties such as dispersibility and coating properties during use. As a result of extensive research into crystalline sol in order to obtain an absorbing material, we discovered that the novel sol of the present invention, which is made of crystalline heptartium oxide, is excellent as an ultraviolet absorbing material, and based on this knowledge, we completed the present invention. This is what I did.

(Means for Solving the Problems) That is, the present invention relates to a crystalline ceric oxide sol and a method for producing the same, and the water bottle invention relates to a ceric oxide sol with a particle size of 300 or less; The invention is a method for producing a crystalline ceric oxide sol, which comprises reacting a cerium salt compound with an alkali metal hydroxide or ammonia to form a gel, and then hydrothermally treating the gel.

(Function) First, the crystalline ceric oxide sol, which is the invention of the water bottle, will be described in detail below.

Until now, no crystalline ceric oxide sol has been known at all.

When neutralizing a water-soluble cerium salt compound with an alkaline agent, the solution may become a sol. However, this is because a small portion of the neutralized precipitate becomes sol-like because it temporarily reaches the colloidal level, and this is amorphous or consists of hydroxide particles. It is a sol-like substance.

Therefore, as the neutralization reaction progresses, this precipitate grows to a large size and becomes a precipitate, and the solution changes from a sol to a gel.

In addition, by removing the acid radicals of the cerium salt compound with an ion exchange resin, or by dissolving the gel obtained by neutralizing the cerium salt compound in an equivalent amount or less of acid (for example, in the case of hydrochloric acid, the composition is Ce(O ) l), C14-ゎ can be obtained), a basic salt aqueous solution or a sol can be obtained.

However, all sol-like materials obtained by such methods are amorphous and unstable.

On the other hand, the ceric oxide sol of the present invention is crystalline, is extremely fine colloidal particles of 300A or less, and is stable in an aqueous solution state, and does not settle even if left for several months. There isn't.

Such a sol has not been previously known and will create new uses in the field of application of ceric oxide-based composite materials.

Further characteristics of the crystalline ceric oxide sol of the present invention are as follows.

First, the sol of the present invention can be obtained as a sol having a high concentration of 40% or more as ceric oxide in a solution state.

Amorphous sols generally have high viscosity, but since the sol of the present invention has a low viscosity and high concentration, it is suitable for use in ultraviolet absorbers, electron beam absorbers, masking agents for IC boards, etc. A film having a desired thickness can be prepared in , - times of coating operations, and a coating film with excellent performance can be obtained.

Furthermore, in coatings of low concentration and high viscosity such as amorphous sol, cracks are likely to occur during drying. Therefore, the coating must be diluted and coated multiple times, but if it dries out, it will return to its original state after the second coating.

Therefore, each time the coating is applied, it is necessary to bake it to form a ceric oxide substance and then apply the coating again, which is an industrially expensive and complicated operation.

Second, the sol of the present invention that is coated and dried becomes only CeO2 and a stabilizer, and contains almost no water, so even when it is fired, there is little weight loss, resulting in a robust coating. A coating is obtained.

In this case, if a cerium salt aqueous solution is used instead of the sol of the present invention, many acid roots and crystal water will still remain even after drying, resulting in crystal precipitation on the substrate, resulting in a porous film and a strong coating. A film cannot be obtained.

Thirdly, the sol of the present invention has excellent properties as an abrasive.

Ceric oxide generally has superior abrasive power compared to zirconium oxide and Bengara, and is therefore in great demand as an abrasive in the field of application.

With recent advances in technology, requirements for surface precision of optical glasses, single crystals, and translucent ceramics have become stricter, and abrasives with finer abrasive grains are required. The sol of the present invention has a small and uniform particle size, and is crystalline, so it has high polishing power, and the desired crystal particle size is 75I! 1J, and satisfies the performance required for these abrasives.

In the present invention, the colloidal particle size was measured by electron microscopic observation, and in the sol of the present invention, substantially all colloidal particles had a particle size of 300λ or less.

Next, a method for producing a crystalline ceric oxide sol, which is the second invention, will be described in detail.

The second invention relates to a method for producing a crystalline ceric oxide sol, which comprises reacting a cerium salt compound with an alkali metal hydroxide or ammonia to form a gel, and then hydrothermally treating the gel. .

The cerium salt compounds used in the present invention include ceric sulfate, 77ium ammonium nitrate, ceric ammonium sulfate, cerous acetate, cerous chloride, 77ium ammonium nitrate, cerous nitrate, Examples include cerium sulfate.

Furthermore, examples of the alkali metal hydroxide include thorium hydroxide, potassium hydroxide, lithium hydroxide, and the like.

In the present invention, first, the cerium salt compound and an alkali metal hydroxide or ammonia are reacted to form a gel.

Regarding the conditions for producing this gel, the temperature during the reaction between the two is approximately 10 to 90°C.

In addition, regarding the usage ratio of these, the equivalent ratio of the alkali metal hydroxide or ammonia (A) and the acid radical (B) derived from the cerium salt compound is approximately 0.9 as A/B.
Each is used so that the range is 1.3 to 1.3.

In addition, in the case of using a cerium-ammonium double salt, the acid radical derived from the ammonium salt is calculated by the amount removed from the above (B).

There is no particular limitation on the order of addition, and either the cerium salt compound and the alkali metal hydroxide or ammonia may be added first, or both may be added and reacted simultaneously.

When using a cerous salt, cerous is gradually oxidized to ceric after gel formation, but due to the long oxidation time and low oxidation rate, it is difficult to oxidize industrially. It is preferable to use agents together.

The gel thus obtained is then filtered and washed to remove impurities in the gel.

This residual impurity needs to be reduced in terms of production and usage of the ceric oxide sol. For example, if the above-mentioned filtration and cleaning operation is not performed at all, the resulting sol will be unstable, and the present invention Can't get sol.

The filtration and washing means are not particularly limited, and any commonly used means such as a filter press, water filtration such as centrifugal filtration, repulp-centrifugation method, etc. can be used.

After filtering and washing, an acid is added to the gel, and the gel is subjected to hydrothermal treatment. The types of acids to be added include hydrochloric acid, nitric acid, acetic acid,
Examples include formic acid, lactic acid, and glycolic acid. The amount of acid added is 0.01 to 1.0 to 1.0 to 1 mole of Ce08 in the gel.
00 moles. In this case, if the amount of acid added exceeds this range, the sol with excellent dispersibility of the present invention cannot be obtained.

In addition, add acid at a hydrothermal treatment F! l! The order of acid addition and hydrothermal treatment is not particularly limited.

Regarding the hydrothermal treatment conditions, the temperature is 100° C. or higher, and generally, the higher the treatment temperature and the longer the treatment time, the better the development of the crystal form and the larger the particle size can be obtained.

In addition, if the treatment is carried out at a temperature below 100°C, the colloidal particles will not crystallize even if it is carried out for a long time, and even if some of them crystallize, the degree of crystallinity will be extremely low and the particles will remain amorphous. Therefore, the object of the present invention cannot be achieved.

According to the method of the present invention, a sol with a desired particle size can be obtained by selecting hydrothermal treatment conditions according to each use of the sol of the present invention, and this can be controlled by selecting the hydrothermal treatment conditions. This point is a major feature of the present invention.

Next, the sol obtained by hydrothermal treatment is subjected to a drying process.

As the drying method, any method such as heat drying, vacuum drying, freeze drying, etc. can be used.

When drying by heating, the drying conditions need to be below the temperature at which the added acid evaporates or changes in quality.

By removing only the moisture in the sol solution by drying and pulverizing it, the sol solution when redissolved becomes extremely stable.

In addition, in the previous step, acid was added before the hydrothermal treatment, and the amount of acid added was 0.2 per mole of Ce02 in the gel.
When the amount is mol or more, the sol of the present invention can be obtained without performing this drying operation.

That is, this drying step is not particularly necessary depending on the selection of manufacturing conditions for the sol of the present invention.

In addition, the sol powder obtained by drying can be adjusted to a desired sol concentration, and can also be dispersed in a solvent other than water to form an organosol. This will further expand its usage.

(Example) Examples of the present invention will be given below to further explain the present invention, but the present invention is not limited thereto.

All percentages are by weight unless otherwise specified.

Example 1 Ceric sulfate aqueous solution (CeL8.0%) 1000
1028 g of aqueous ammonia (NH34, 0%) was added under stirring to form a gel.

This was thoroughly washed with water until no 804'-ions were observed in the filtrate, to obtain a gel containing 21.0% CeO□.

200g of this gel has a HN O9/Ce O2 molar ratio of 0.
．． Add 2.5 g of nitric acid (HN0361%) and 322 g of water so that the amount of
Hydrothermal treatment was performed at 0°C for 15 hours.

After the hydrothermal treatment, this slurry was dried at 100°C until it became a star, to obtain a powder of the sol of the present invention.

When this sol powder was analyzed, Ce0p92.5
%, NO33,3%8040%.

In addition, when this sol powder was dispersed in water to prepare a CeO2 1.0% sol and left to stand, the dispersion rate after one month was 9.
The colloid particle size was measured by transmission electron microscopy, and the average particle size was 90%.

Furthermore, the sol of the present invention was subjected to X-ray diffraction measurement, and the diffraction pattern is shown in FIG.

As is clear from Figure 1, the reason why the diffraction peak is broad is that, as can be understood from the 5cherrer equation,
This is because the particle size of the crystalline ceric oxide sol of the present invention is quite small at 90 mm.

In the measurement of X-ray diffraction, the X-ray diffraction device used was Rigaku RAD・-Ia type, and a Cu tube was used at 30K.
The test was carried out under conditions of V and 20 mA.

Example 2 CH3CO0)1/Ce was added to 100 g of the gel obtained by the reaction of ceric sulfate and aqueous ammonia in Example 1.
Add 1.8 g of glacial acetic acid and 3 ml of water to give an O2 molar ratio of 0.25.
Add 20g, put this in an autoclave, and add 200g.
A hydrothermal treatment was carried out at 'C for 24 hours to obtain the sol of the present invention.

When this sol solution was analyzed, it was found that CeO□5.0%,
5O4O%, C1 (3COOH 0.4%).

In addition, this sol was dried at 80°C until it reached a constant weight.
The dried product was subjected to X-ray diffraction measurement in the same manner as in Example 1, and the diffraction pattern is shown in FIG.

Further, the colloid particle size was measured by transmission electron microscopy, and the average particle size was 170'A.

In addition, in X-ray diffraction, the d (input) value is 3.12.1691
．． It was 1.63, but this is the JCP that describes the diffraction value.
DS card (Joint Comm1ttee on
Powder Diffraction 5tanda
rcl) According to the 1986 edition, it is identified as ceric oxide crystal (Cerianite).

Example 3 Ceric ammonium nitrate aqueous solution (CeO22,0
%) 5000g and thorium hydroxide aqueous solution (Na1.5
%) were simultaneously added to a reaction tank to which 1000 g of water had been previously added, using separate metering pumps, while stirring, over a period of about 1 hour. The temperature of the reaction solution at this time was 21°C.

After the reaction, the gel was filtered, washed with water, and Ce021? , 33%, N
A cake containing 0.3% O3, Na, and NH3 of 20 ppm or less was obtained.

Add 145 g of water to 200 g of this wet cake to make a uniform slurry, put it in an autoclave, and heat it to 180 g.
Hydrothermal treatment was performed at ℃ for 15 hours.

After the hydrothermal treatment, 5.2 g of nitric acid (HN0361%) was added and mixed uniformly.

This slurry was dried at 100'C until a constant weight was obtained to obtain the sol of the present invention.

This sol powder was dispersed in water to give 35% Ce02, which had excellent fluidity despite its high concentration.

Next, a sol prepared to have Ce026% was coated on quartz glass.

The coating equipment is Mikasa spinner 1) 1
-02 type was used.

After coating the sol on glass, it is dried,
Next, baking was performed at 500°C for 1 hour.

In order to observe the absorption in the ultraviolet to visible range of the coated glass after firing, we used a spectrophotometer (UV-260 manufactured by Shimadzu Corporation).
The light transmittance in the wavelength range of 190 to 900 nm was measured using a mold).

The results are shown in Figure 2.

For comparison, a titanium oxide sol was produced using the method described below, and the light transmittance from the ultraviolet to the visible region was similarly measured.
The results are shown in Figure 2. (Comparative Example (Production method of titanium oxide sol) 812 g of ammonia water (NH, 2.0%) was added to 600 g of titanium tetrachloride aqueous solution (TiO 83.0%) under stirring for about 1 hour, and a gel was obtained. Ta.

After filtering the generated gel, water injection filtration and washing were performed until no chloride ions were observed in the gel.

To 100g of this gel, 1 ammonia water (NH, 2.0%)
Add 6g and 24g of water, transfer this to an autoclave,
Hydrothermal treatment was performed at 120°C for 10 hours, and Ti
0.026% titanium oxide sol was obtained.

As is clear from FIG. 2, it can be seen that the example of the present invention has a superior ultraviolet absorption ability than the titanium oxide of the comparative example.

Example 4 Ceric ammonium sulfate solution CCeO32.5%
) Tooog ammonia water (NH34, 2%) 260
g under stirring at room temperature to form a gel.

After filtering the generated gel, washing was performed until 304 ions were no longer observed in the gel.

As a result of analyzing this gel, it was found that at 5% CeO2, NH3
No ions were detected.

CH3COOH/CeO to 100g of this gel. molar ratio 0
．． 4, add 3.3 g of acetic acid and 130 g of water,
This was placed in an autoclave and subjected to hydrothermal treatment at 130°C for 15 hours, and then this slurry was freeze-dried to a constant weight to obtain the sol of the present invention.

Water was added to this sol powder to make a 15% I:'eo sol, and this and polyvinyl alcohol (Nippon Gosei Chemical Co., Ltd.
Ce0I2/Ho0
A solution having a richenyl alcohol weight ratio of 0.05 was prepared.

Pour this solution into a 100 x 100 mm mold,
Dry at 40°C for about 70 hours, 100X100X1
A film of 00.2+nm17 was obtained.

This film transmits light from the visible region to the ultraviolet region! AI! was measured, and the results are shown in Figure 3.

[Brief explanation of the drawing]

FIG. 1 is an X-ray diffraction diagram of the crystalline ceric oxide sols of the present invention obtained in Examples 1 and 2. FIG. 2 is a diagram showing the light transmittance in the ultraviolet to visible region of the crystalline ceric oxide sol and titanium oxide sol of the present invention obtained in Example 3, which were subjected to glass coating treatment. FIG. 3 is a diagram showing the light transmittance in the ultraviolet to visible region of a polyvinyl alcohol film containing the crystalline ceric oxide sol of the present invention obtained in Example 4. Patent applicant: Taki Chemical Co., Ltd. Nizuwo Gin)

Claims (2)

[Claims] (1) Crystalline ceric oxide sol with a particle size of 300 Å or less. (2) A method for producing a crystalline ceric oxide sol, which comprises reacting a cerium salt compound with an alkali metal hydroxide or ammonia to form a gel, and then hydrothermally treating the gel.