JPH02137733A - Crystallized zirconia-based sol - Google Patents

Abstract

PURPOSE:To provide sol useful for producing synthetic fibers and resins, having fine dispersed particle diameter of zirconia and excellent dispersibility by consisting a dispersion medium essentially of dimethyl sulfoxide. CONSTITUTION:This crystallized zirconia-based sol comprises dimethyl sulfoxide (DMSO) as a main component of dispersion medium. This sol, for example, is obtained by adding DMSO to aqueous crystallized zirconia-based sol and dehydrating under heating. The sol has fine dispersed particle diameter of zirconia particles and excellent dispersibility and dispersion stability so that the sol is useful as a raw material for producing fibers and resins and can effectively eliminate deterioration of strength, etc., especially in production of acrylic fibers, etc. Since DMSO is much used in production of various resins and acrylic fibers, the sol can be readily applied to resins and fibers.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a crystallized zirconia-based sol useful as a raw material for producing fibers and resins composited with zirconia.

<Prior Art> In recent years, zirconia has attracted attention as a material that emits far-infrared rays with high efficiency, and the usefulness of fibers and resins composited with this zirconia is being evaluated.

Traditionally, most crystallized zirconia-based sols have been obtained as aqueous sol by heating an aqueous solution of zirconium salt, but recently crystallized zirconia-based sols have been obtained by dispersing zirconia in organic solvents such as alcohol, acetone, and benzene. oxidized zirconia-based sol (JP-A-62-2268
No. 15) and crystallized zirconia-based sol in which zirconia is dispersed in various alcohols including polyhydric alcohols (
Japanese Patent Application Laid-Open No. 63-2809) is known.

<Problems to be Solved by the Invention> However, although the conventional organic solvent-based crystallized zirconia sol can be suitably used as a raw material for cosmetics and paints, it has problems with its particle dispersibility, etc.
There was still room for improvement as a raw material for producing navy blue and resin.

Therefore, the problem of the present invention is that the dispersed particle size of zirconia is V &
The object of the present invention is to provide a novel crystallized zirconia-based sol that is fine and has excellent dispersibility and is particularly suitable as a raw material for producing synthetic fibers such as acrylic fibers and resins.

<Means for Solving the Problems> That is, the gist of the present invention is a crystallized zirconia-based sol characterized in that the main component of the dispersion medium is dimethyl sulfoxide.

The crystallized zirconia-based sol of the present invention is, for example, a water-based crystallized zirconia-based sol with dimethyl sulfoxide (hereinafter referred to as
It can be obtained by adding DMSO (abbreviated as DMSO) and dehydrating it by heating.

Any method can be used to produce the aqueous crystallized zirconia sol used as a raw material, but for example, an aqueous suspension containing zirconium hydroxide is sufficiently heated at a temperature of 80°C or higher. It can be produced by maintaining the heated state until crystallization, then adding an acid or alkali to the obtained crystallized zirconia-containing aqueous mixture and plating it.

The present invention will be explained in detail below.

The aqueous mixture containing crystallized zirconia is a mixture of crystallized zirconia and an aqueous solvent, and this mixture may be in the form of an aqueous suspension or a gator containing an aqueous solvent.

The aqueous solvent used can contain lower alcohols such as methanol, ethanol, propatool and butanol, ketones such as acetone, or a mixed solvent thereof.

The aqueous mixture containing crystallized zirconia may contain, in addition to zirconia, oxides of other elements that can be dissolved in zirconia. Such elements preferably include alkaline earth metals, clay groups, rare earths, etc. Examples include elements such as, more preferably, magnesium, calcium, yttrium, cerium, and the like. Among them, yttrium and cerium are most preferably used.

The aqueous mixture containing crystallized zirconia is obtained by a hydrothermal synthesis method consisting of heating an aqueous suspension containing zirconium hydroxide.

Various methods can be used to produce an aqueous suspension containing zirconium hydroxide. For example, it can be obtained by mixing zirconium hydroxide with an aqueous solvent. It is obtained by neutralizing an aqueous solution of a zirconium salt such as zirconium or zirconium nitrate with a base, but it is also possible to neutralize a mixed aqueous solution of a zirconium salt and a salt of another element that can be dissolved in zirconia, such as yttrium chloride, with a base. It can be obtained by neutralization coprecipitation.

Here, the zirconium salt includes zirconyl salts such as zirconyl chloride. In addition, examples of bases include ammonia, sodium hydroxide, and potassium hydroxide, but in addition to these, compounds such as urea that become basic when thermally decomposed can also be used, and these bases are usually Used in the form of an aqueous solution.

In addition, it goes without saying that "zirconium hydroxide" and "zirconia" in the above also include those with a general meaning that contain 10% or less of hafnia and other V& amount impurities that are normally contained. .

The concentration of the aqueous suspension containing zirconium hydroxide is preferably 1 mol/a or less.

When performing neutralization coprecipitation, it is preferable to simultaneously mix an aqueous solution containing zirconium and salts of other elements and an aqueous base solution with stirring.

If the aqueous suspension containing zirconium hydroxide contains a large amount of ions as impurities, such as chloride ions, the aqueous suspension containing zirconium hydroxide should be washed before being heated; Alternatively, it is preferable to wash the crystallized zirconia-containing aqueous suspension obtained by keeping it in a heated state. Washing is typically accomplished by removing the aqueous solvent and adding fresh aqueous solvent, repeated as necessary. For example, when an aqueous suspension containing zirconium hydroxide is obtained by neutralizing zirconyl chloride and aqueous ammonia, excess ammonium chloride is removed by filtration, etc., and then a new aqueous solvent is added to the solid content to form a suspension. It can be cleaned by doing this. As the new water/specific solvent used here, those similar to the aqueous solvent constituting the aqueous suspension can be used.

By washing in this way, the sol is destabilized and
Since the ions to be aggregated can be removed in advance, a stable fine zirconia-based sol can be obtained.

Cleaning is preferably carried out until the amount of impurity ions is 3 mol % or less, particularly 0.3 mol % or less, based on zirconia.

By heating an aqueous suspension containing zirconium hydroxide, most of the zirconium hydroxide is converted to crystallized zirconia.

The heating temperature is preferably 80°C or higher, more preferably 140°C or higher. A heating temperature of less than 80°C is undesirable because it will take an extremely long time for the crystallized product to grow sufficiently.The upper limit of the heating temperature is not particularly limited, but industrially it is preferably 300°C or less.

Heating is maintained until a sufficient amount of crystallized material is formed. The heating holding time is not particularly limited, but for example, 150°C
It is sufficient to heat for 12 hours or more at 200°C for 2 hours. Heating and holding is preferably carried out until the crystallinity of the produced zirconia reaches 80% or more.
A stable sol can be produced by obtaining 0% or more of zirconia, but in order to obtain a more stable sol, it is preferable that the degree of crystallinity is 90% or more.

In addition, the degree of crystallinity in this case refers to 100% of zirconia purified by heating an aqueous suspension containing 0.3 mol/n of zirconium hydroxide in a pressure vessel at 200°C for 24 hours.
% crystallized product, and is expressed as a relative value by comparing the areas of the (111) plane peaks of zirconia in charts obtained by X-ray analysis measurement.

During heating and holding, the presence of hydrogen peroxide, sodium hydroxide, potassium hydroxide, etc. generates a fine sol, so these additions are preferably carried out. In addition, by changing the type, concentration, heating temperature, etc. of additives such as sodium hydroxide and potassium hydroxide, it is possible to shorten the reaction time and obtain crystallized zirconia-based sols with various crystal forms. .

An aqueous suspension containing crystallized zirconia is thus obtained. By removing the aqueous solvent from this suspension by heating or vacuum filtration, an aqueous solvent-containing crystallized zirconia suspension or gator is obtained.

Next, an acid or alkali is added to the aqueous mixture containing crystallized zirconia to peptize the zirconia.

Examples of the acid added here include hydrochloric acid, nitric acid, acetic acid, and lactic acid. Examples of alkali include dimethylamine, diethylamine, di-n-propylamine, etc.
Secondary amines such as propylamine and diisopropylamine, ammonia, quaternary ammonium hydroxides such as tetramethylammonium hydroxide, tetraethylammonium hydroxide and tetra-n-propylammonium hydroxide, sodium hydroxide, potassium hydroxide and Examples include calcium hydroxide. These acids or alkalis are usually used as aqueous solutions.

The amount of these additions varies depending on the type of acid or alkali, but when using an acid, the pH is 0°1 to 5.0,
It is particularly preferable to add it in a range of 0.5 to 3.0. In addition, when using alkali, the pH is 8 to 1.
4, especially preferably in the range of 10 to 13.

Further, it is more preferable to reflux under heating during peptization.

Furthermore, it is also possible to adopt a method in which, after adding an acid or alkali, the acid or alkali is directly evaporated to dryness, and then added to an aqueous solvent. Here, the evaporation to dryness is preferably carried out at 200°C or lower, and can be carried out under reduced pressure, increased pressure, or normal pressure. Among these, it is more preferable to carry out drying at a temperature of 100°C or less under reduced pressure. In this case, if the drying temperature is high, the acid or base that stabilizes the sol is removed, resulting in agglomeration of crystallized particles. This will lead to deterioration of sol properties such as broadening of particle size distribution.

The degree of evaporation to dryness is preferably such that the weight loss ratio is about 15 to 1% by weight, particularly about 10 to 3% by weight, based on the weight after firing at 800°C.

As the aqueous solvent to which the solid mass obtained by evaporation to dryness is added, the same aqueous solvent as that used in the aqueous mixture containing crystallized zirconia used as a raw material can be used.

In this way, the zirconia is peptized and RM water-based crystallized zirconia dispersed in an aqueous solvent is obtained.

The amount of aqueous solvent in such a sol is preferably 1 to 100 times the total amount of continuous zirconia and other solids by weight.

By adding DMSO to the zirconia sol obtained in this manner and removing water, the crystallized zirconia sol of the present invention can be obtained.

Methods for removing water include, but are not particularly limited to, a method of removing by heating, a method of removing using a dehydrating agent or a reverse osmosis membrane, and the like. If it is desired to further adjust the pH, an acid or alkali can be added or removed within a range that does not impair the dispersibility of the zirconia particles.

In this way, a crystallized zirconia-based sol is obtained in which the main component of the dispersion medium is DMSO and has excellent dispersibility and dispersion stability.

In the present invention, the crystallized zirconia sol in which the main component of the dispersion medium is DMSO refers to DMS with a water content of 10% by weight or less.
This refers to a crystallized zirconia-based sol that is dispersed and stabilized with O, but other solvents may be added as long as they do not affect the stability of the sol.

Examples of solvents that can be used in combination include water and water-soluble organic solvents. Examples of water-soluble organic solvents include alcohols such as methanol and ethanol, polyhydric alcohols such as glycerin and butanediol, ketones such as acetone, and phenols.

The crystallized zirconia-based sol in which the main component of the dispersion medium of the present invention is DMSO includes not only a sol of zirconia alone, but also zirconia containing an oxide of an element that can be solid-dissolved in the zirconia. Further, the crystallized zirconia-based sol of the present invention may have any cubic, square, or monoclinic crystal lattice.

<Example> Hereinafter, the present invention will be specifically explained with reference to Examples.

Implementation PA1 Aqueous solution of zirconyl 1,2 chloride containing cerium chloride to contain 6 mol% of ceria based on zirconia 200
ml and 200 ml of 5.16M ammonia water were added simultaneously to coprecipitate zirconium hydroxide and yttrium hydroxide.

The obtained slurry was placed in a pressure-resistant container (volume: 500 ml) and heat-treated at 150° C. for 24 hours.

The resulting cerium-containing zirconia slurry with a crystallinity of 90% was washed 5 times with 500 ml of distilled water, and 20+ nt of acetic acid was added to 50 g of the resulting cake, stirred, and then dried in a rotary evaporator at 800'C. Reduced J
A solid mass of 16.3% by weight was obtained.

When 80 ml of water was added to this solid mass 20+r, it was dispersed into a sol.

After adding 80 ml of DMSO to this, water and acetic acid were evaporated by heating, and a DMSO-based sol with excellent dispersibility and stability was obtained.

Example 2 200 ml of 1.2M zirconyl chloride aqueous solution and 4.
Zirconium hydroxide was precipitated by simultaneously adding 200 m+ of 8M aqueous ammonia.

The obtained slurry was placed in a pressure-resistant container (volume: 500f!+I)
and heat-treated at 150° C. for 24 hours.

The generated zirconia slurry with a crystallinity of 90% was
Wash 5 times with ml of distilled water, add 0 to 50 g of the resulting cake.
．． After adding 100 ml of 5% aqueous hydrochloric acid solution and stirring, the mixture was dried at 70°C using a rotary evaporator.

When 50 ml of water was added to 20 ml of the obtained dry mass and stirred, it was dispersed to form a sol.

80 ml of DMSO was added to this, and the pH was adjusted to 6 or higher using an anion exchange resin.

After that, water is removed by reducing pressure and heating, and the MSO becomes stable.
A system sol was obtained.

Example 3 A test was carried out in the same manner as in Example 1 using an aqueous solution of 1,200 zirconyl chloride containing yttrium chloride so as to contain 3 mol% of yttrium based on zirconia.
Similarly, a DMSO-based sol with excellent dispersibility and stability was obtained.

<Effects of the Invention> As explained above, the crystallized zirconia-based sol of the present invention, in which the main component of the dispersion medium is DMSO, has fine dispersed zirconia particles and has excellent dispersibility and dispersion stability. Therefore, it is useful as a raw material for producing fibers and resins, and in particular can effectively eliminate problems such as strength deterioration when producing acrylic fibers.

Furthermore, since DMSO used as a dispersion medium is a solvent often used in the production of various resins and acrylic fibers, the crystallized zirconia-based sol of the present invention can be easily applied to resins and fibers. can.

Claims (1)

[Claims] A crystallized zirconia-based sol characterized in that the main component of the dispersion medium is dimethyl sulfoxide.