JP2001348220A - Spherical leucite crystal and manufacturing method thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To form spherical leucite crystal and to disperse precisely and homogeneously a prescribed quantity thereof in a matrix. SOLUTION: The spherical leucite crystals 2, 4 and 6 are manufactured through a process of mixing K2SO4, Al2(SO4)3 and SiO2 in the ratio of 90-50 mol% K2SO4, 5-15 mol% Al2(SO4)3 and 5-35 mol% SiO2, a process of heating the mixture at 900-1200 deg.C and a process of cleaning after the heating process.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a spherical leucite crystal which can be suitably used as an additive to be mixed or dispersed in a matrix of glass, ceramic, resin, metal or the like, and a method for producing the same.

[0002]

2. Description of the Related Art Leucite crystals (KAlSi)
_{2 O 6)} has a melting point as high as 1693 ° C., further, since the thermal expansion coefficient and high 3.1 × 10 -5 ^/ degree, mixed in a matrix of glass or ceramic or dispersion to adjust the thermal expansion coefficient It can be suitably used for Glasses containing leucite crystals have been developed.
-662. In order to produce glasses containing leucite crystals, SiO ₂ or A
A glass material containing an oxide such as l ₂ O ₃ or K ₂ O is heat-treated to precipitate leucite crystals in a glass matrix. Alternatively, irregular leucite grains produced by pulverizing natural leucite are mixed or dispersed in a matrix.

[0003]

[Problems to be Solved by the Invention] SiO ₂ and Al ₂ O
_In the technique of heat-treating a glass material containing an oxide such as ₃ or K ₂ O to precipitate leucite crystals in a glass matrix, it is difficult to accurately adjust the amount of leucite crystals to be precipitated. It is difficult to adjust the physical properties of a kind to the intended state or value. Further, in this method, the material of the matrix is limited, and for example, leucite crystals cannot be precipitated in the resin. On the other hand, in the method of mixing or dispersing amorphous leucite crystal grains produced by crushing natural leucite into a matrix, the leucite crystal grains are homogeneous in the matrix because they are amorphous. Difficult to disperse. For this reason, physical properties of glass, ceramic, resin, and the like are not uniform.

[0004]

Therefore, in the present invention,
An object of the present invention is to produce a spherical leucite crystal so that a predetermined mixing amount can be accurately and homogeneously dispersed in a matrix.

[0005]

Means for Solving the Problems, Action and Effect In the present invention, a spherical leucite crystal having a spherical or substantially spherical crystal shape, which is a leucite (KAlSi ₂ O ₆ ) crystal, was successfully synthesized. This spherical leucite crystal has a spherical or substantially spherical crystal shape. Therefore, it can be easily and homogeneously dispersed in the matrix. Further, the amount of dispersion or the amount of mixture in the matrix can be adjusted accurately. Further, it can be dispersed in a matrix other than glass.

In the present invention, a method for synthesizing this spherical leucite crystal was successfully created. In this synthesis or production method, K ₂ SO ₄ , Al ₂ (SO ₄ ) ₃ and SiO ₂ are
₂ SO ₄ : 90 to 50 mol%, Al ₂ (SO ₄ ) ₃ : 5
１５15 mol%, SiO ₂ : 5-35 mol%, a step of heating the mixture to a temperature range of 900 ° C. to 1200 ° C., and a step of washing after the heating step to form spherical leucite crystals. To manufacture. According to this production method, a spherical leucite crystal having a spherical or substantially spherical crystal shape can be synthesized.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, a spherical lucy of the present invention will be described.
Example of one of the preferred embodiments of the method for producing a crystal
Show. As a starting material, K₂SO₄And Al
₂(SO₄)₃・ 14-18H ₂O and SiO₂Using
Was. Where SiO₂Represents an amorphous film having an average diameter of about 10 μm.
Lake-like particles were used. Al₂(SO₄)₃・ 14-1
8H₂O is heated in air at 300 ℃ for more than 12 hours
And Al₂(SO₄)₃And

FIG. 1 shows a schematic ternary phase diagram when a mixture of K ₂ SO ₄ , Al ₂ (SO ₄ ) ₃ and SiO ₂ is kept at 1000 ° C. for 3 hours. In the composition shown by the large circle in FIG.
Only leucite crystals were produced. In the composition indicated by the small circle in FIG. 1, it was confirmed that not only leucite crystals but also mullite (Al ₆ Si ₂ O ₁₃ ) crystals and amorphous silica (amorphous SiO ₂ ) were present. In the present embodiment, in order to generate only the leucite crystal,
As an example of the mixing ratio, K ₂ SO ₄ : Al ₂ (S
A molar ratio of O ₄ ) ₃ : SiO ₂ = 5.9: 1.0: 1.1 is used. As shown in FIG. 1, the mixing ratio is in a range surrounded by a solid line, that is, K ₂ SO ₄ : 90 to 50 mol.
%, Al ₂ (SO ₄ ) ₃ : 5 to 15 mol%, SiO ₂ :
It is in the range of 5-35 mol%.

The mixture (20 grams) having the above mixing ratio is placed in an alumina crucible (height: 70 mm, diameter: 50 mm), covered with alumina, and heated at a predetermined temperature (900 to 1200).
(° C) at a heating rate of 10 ° C / min. Hereinafter, the mixture refers to K ₂ SO ₄ , Al ₂ (SO ₄ ) ₃ and S
It refers to a mixture of iO ₂ . The alumina crucible and the mixture placed in the alumina crucible are maintained at the above-mentioned predetermined temperature for a predetermined time. For example, when heated to 1000 ° C., the temperature is maintained at 1000 ° C. for 3 hours. The product after heating and holding is cooled in a furnace to room temperature to perform a melting treatment. In the dissolution treatment, the product is treated with a hydrochloric acid solution (1 mol
/ L) for 0.5 to 1 hour to remove the flux adhering to the spherical leucite crystals. Thereafter, the resultant is washed with water and dried to obtain spherical leucite crystals in white particles.

FIG. 2 shows a scanning electron microscope (SEM) photograph of the spherical leucite crystal obtained by the above method. In FIG. 2, the photographs a and b are photographs having different magnifications. Photograph a shows a large number of spherical or substantially spherical spherical leucite crystals. As can be seen from the photographs a and b, most of the spherical leucite crystals have a diameter of 70 to 110 μm and an average particle diameter of 84 μm. In Photo a, a single spherical leucite crystal is also observed to adhere to each other. In photograph b, which has a higher magnification than photograph a, the surface of the spherical leucite crystal looks smooth. Also, it can be seen that there are "steps" on the surface. In FIG. 2, photograph c (photograph b is the same magnification as photograph b) is obtained by observing broken spherical leucite crystals. It can be seen that the spherical leucite crystal has a dense structure.

In FIG. 1, a range surrounded by a solid line, that is, K ₂ SO ₄ : 90 to 50 mol%, Al ₂ (SO _{2
4) 3: 5~15mol%, SiO} 2: In 5～35Mol% range, leucite crystals produced exhibits a spherical shape. In the above description, the heating temperature was 1000 ° C.
Spherical leucite crystals are obtained in the temperature range from 00 ° C to 1200 ° C.

K ₂ SO ₄ : Al ₂ which is an example of the mixing ratio
It shows that spherical leucite crystals are produced even at a heating temperature other than 1000 ° C. using a mixture having a molar ratio of (SO ₄ ) ₃ : SiO ₂ = 5.9: 1.0: 1.1.

[0013] Three samples of the mixture having the above molar ratio were prepared, and 900 ° C. and 1000
FIG. 3 shows an X-ray diffraction (XRD) pattern when the temperature was raised to 1100 ° C. and held at that temperature for 3 hours.
The vertical axis is the diffraction intensity, and the horizontal axis is the diffraction angle. 3, the X-ray diffraction patterns are 900, 1000, and 1100 in order from the bottom.
It is an X-ray-diffraction pattern, while each was hold | maintained for 3 hours. In the figure, an asterisk indicates a diffraction peak of a leucite crystal, and a triangle indicates a diffraction peak of a mullite crystal. In addition, 3
When X-ray diffraction is performed on the product after holding for a time, a product that has been dissolved with hot hydrochloric acid (70 to 80 ° C., 0.5 to 1 hour) is used.

Although the crystal phase of the sample kept at 900 ° C. for 3 hours is only the leucite crystal phase, the peak intensity is relatively weak. What was kept at 1000 ° C. for 3 hours indicates that only the leucite crystal phase was present. 1100 ° C
3 hours indicates that not only the leucite crystal phase but also the mullite crystal phase was present.
Therefore, K ₂ SO ₄ : Al ₂ (S
It can be seen that with a composition having a molar ratio of O ₄ ) ₃ : SiO ₂ = 5.9: 1.0: 1.1, as the heating temperature increases, not only leucite but also mullite is easily generated.

Next, K ₂ SO ₄ : one example of the mixing ratio:
Al ₂ (SO ₄ ) ₃ : SiO ₂ = 5.9: 1.0: 1.
The mixture at a molar ratio of 1 was heated to 1000, an example of a heating temperature.
The effect of the holding time on the formation of spherical leucite crystals when held at ° C. will be described.

FIG. 4 shows a scanning electron micrograph. In FIG. 4, since the subject of the photograph a is small, only the photograph a, the photographs b to d
The image is photographed at a magnification of about 1.5 times higher than that of the photograph. X in FIG.
3 shows a line diffraction pattern. The vertical axis is the diffraction intensity, and the horizontal axis is the diffraction angle. In FIG. 5, the X-ray diffraction pattern shows that the mixture having the above molar ratio is 0, 1, 2, and 12 hours in order from the bottom.
It is an X-ray diffraction pattern while keeping at 000 ° C.
An asterisk in the figure indicates a diffraction peak of a leucite crystal. In addition, when performing X-ray diffraction on the product held at 1000 ° C., the product was dissolved with hot hydrochloric acid (70 to 80).
C., 0.5 to 1 hour).

Photograph a in FIG. 4 shows that the mixture was heated from room temperature to 1000 ° C. at a heating rate of 10 ° C./min, and then rapidly cooled to room temperature without holding at 1000 ° C. (hereinafter referred to as “0 hour holding”). It is a photograph. Fine particles are found to be agglomerated. No spheres are seen. In the X-ray diffraction pattern of the sample held for 0 hours shown at the bottom in FIG. 5, only a halo diffraction peak indicating amorphous and a diffraction peak of leucite crystal are not observed. Accordingly, the fine particles in the photograph a in FIG.
₂ .

Photograph b in FIG. 4 shows that the mixture was heated from room temperature to 1000 ° C. at a heating rate of 10 ° C./min to 1000 ° C.
It is the photograph which image | photographed what cooled rapidly to room temperature after holding | maintenance for time. Spheroids are seen. However, the number of the spheres is small. In the X-ray diffraction pattern of the sample held for 1 hour, shown second from the bottom in FIG. 5, the diffraction peak of the leucite crystal is seen, but the diffraction peak intensity is weak. A halo diffraction peak indicating amorphous is also seen. Therefore, the fine particles in the photograph b in FIG.
iO ₂ and the spheres are spherical leucite crystals.

Photograph c in FIG. 4 shows that the temperature of the mixture was raised from room temperature to 1000 ° C. at a heating rate of 10 ° C./min.
It is the photograph which image | photographed what cooled rapidly to room temperature after holding | maintenance for time. Many spherical objects are seen. In the X-ray diffraction pattern of the sample kept for 2 hours, which is shown third from the bottom in FIG. 5, the diffraction peak of leucite crystal is seen, and the halo diffraction peak is not seen. Therefore, in photograph c in FIG. 4, although unreacted amorphous SiO ₂ fine particles due to the starting material are also observed, it can be seen that many spherical leucites, which are spherical, are formed.

Photograph d in FIG. 4 shows that the mixture was heated from room temperature to 1000 ° C. at a heating rate of 10 ° C./min to 1000 ° C.
It is the photograph which took what cooled rapidly to room temperature after 2 hours holding. The shape of the sphere is the same as that kept at 1000 ° C. for 2 hours, but the size is different. In the X-ray diffraction pattern of the sample held for 12 hours shown in the lowermost upper part in FIG. 5, only the diffraction peak of the leucite crystal is seen.
Therefore, it can be seen from photograph d in FIG. 4 that only spherical leucite having a size different from that maintained at 1000 ° C. for 2 hours is generated. In Photo d, spherical leucite crystals having a larger particle size than those maintained at 1000 ° C. for 2 hours are formed.

As described above, the range surrounded by the solid line in FIG. 1, that is, K ₂ SO ₄ : 90 to 50 mol%, Al ₂ (S
K ₂ SO ₄ : Al ₂ (S) which is an example in a range of a ratio of O ₄ ) ₃ : 5 to 15 mol% and SiO ₂ : 5 to 35 mol%
It can be seen that a spherical leucite crystal can be obtained from a mixture having a molar ratio of O ₄ ) ₃ : SiO ₂ = 5.9: 1.0: 1.1 by keeping the heating temperature at 1000 ° C. for 2 hours or more. .

FIG. 6 shows the relationship between the holding time (2 to 12 hours) at a heating temperature of 1000 ° C. and the average particle size of the spherical leucite crystals. The vertical axis represents the average particle size, and the horizontal axis represents the retention time. It can be seen that the average particle size increases as the holding time increases. After 12 hours, the average particle size was 115
μm.

By using this method, the particle size of the spherical leucite crystals can be controlled by controlling the heating and holding time of the mixture. If the holding time is shortened (at a heating temperature of 1000 ° C., a holding time of at least 2 hours is required), a spherical leucite crystal having a small particle size can be obtained. In addition, if the heating temperature is different, the reaction rate is also different. Therefore, by controlling the heating temperature (900 to 1200 ° C.),
The particle size of the spherical leucite crystals can also be controlled.
Even if the heating temperature is 900 ° C., if the holding time is long, spherical leucite crystals can be obtained. If the heating temperature is high, a spherical leucite crystal having a desired particle size can be obtained quickly.
At a heating temperature higher than 1200 ° C., the amount of mullite generated increases. Therefore, a heating temperature higher than 1200 ° C. is not used in the present method.

From the above, it can be seen that the present invention makes it possible to synthesize a spherical or substantially spherical spherical leucite crystal. Therefore, the amount of dispersion or mixing in the matrix can be accurately adjusted by the spherical leucite crystals produced according to the present invention. Also,
The spherical leucite crystals produced according to the present invention can be dispersed in matrices other than glasses.

In this embodiment, Al ₂ (SO ₄ ) ₃ is
l ₂ (SO ₄ ) ₃ · 14-18H ₂ O at 300 degrees for 12
Heated in air for more than an hour, but not limited to 18-hydrate. In addition, Al ₂ (SO ₄ ) ₃ is stable in a hydrated state at room temperature, so that it is dehydrated by heating before mixing to form an anhydrous salt. However, the temperature and time of dehydration by heating are not limited to the above conditions. It is sufficient that Al ₂ (SO ₄ ) ₃ is in an anhydrous salt state before mixing. In the present embodiment, A is used as the reagent powder.
l _{2 (SO 4)} Since 3 · 14-18H ₂ O is available on the _general, Al 2 _{(SO 4) 3} for Al ₂ as precursors
_{(SO 4)} merely by using 3 · 14-18H ₂ O.

In this embodiment, SiO 2₂As amorphous
Use porous particles. This form of SiO ₂Is rich in reactive activity
Therefore, it is easy to suitably generate spherical leucite crystals,
The shape and size are not limited.

The heating rate up to the predetermined temperature in this embodiment is 10 ° C./min, but is not limited to this heating rate.

The lid made of alumina used in the present embodiment is for preventing dust from entering, and the material is not limited to alumina. It is sufficient that dusts can be prevented from mixing and do not react with the mixture in the alumina crucible.

In the present embodiment, in the dissolution treatment, 7
It is immersed in a hydrochloric acid solution (1 mol / l) at 0 to 80 ° C. for 0.5 to 1 hour, but is not limited to these temperatures and times. It is sufficient that the flux attached to the spherical leucite crystals generated after heating can be appropriately removed, and other acids than hydrochloric acid may be used. If it takes a sufficient time for washing, instead of pickling, it may be merely washed with water.

[Brief description of the drawings]

FIG. 1 shows a schematic ternary phase diagram of K ₂ SO ₄ , Al ₂ (SO ₄ ) ₃ and SiO ₂ .

FIG. 2 is a scanning electron microscope (SEM) showing the appearance and fracture surface of the spherical leucite crystal of the present invention according to the present embodiment.
It is a photograph.

FIG. 3 is a graph showing an X-ray diffraction (XRD) pattern measured in the present embodiment. The three samples with different heating temperatures are also shown.

FIG. 4 is a scanning electron microscope (SEM) photograph showing the appearance of the spherical leucite crystal and the like of the present invention according to the present embodiment.

FIG. 5 is a graph showing an X-ray diffraction (XRD) pattern measured in the present embodiment. The four samples with different retention times are also shown.

FIG. 6 is a graph showing the relationship between retention time and the average particle size of spherical leucite crystals.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Akiyoshi Yamaguchi 5-5-3 Iwanaridai, Kasugai-shi, Aichi Prefecture (72) Inventor Shinobu Hashimoto 1-401 Inoko Ishige House 1-70 Heiwagaoka, Meito-ku, Nagoya City, Aichi Prefecture F term (reference) 4G073 AA02 BD01 CM01 FB04 FB11 FB21 FD23 UA08 UB01 UB08 UB41

Claims (2)

[Claims] 1. A spherical leucite crystal which is a leucite (KAlSi ₂ O ₆ ) crystal and has a spherical or substantially spherical crystal shape. 2. K ₂ SO ₄ , Al ₂ (SO ₄ ) ₃ and Si
O ₂ is converted into K ₂ SO ₄ : 90 to 50 mol%, Al ₂ (SO _2
4 ) A step of mixing at a ratio of ₃ : 5 to 15 mol% and SiO _{2 at} a ratio of 5 to 35 mol%, and mixing the mixture at 900 ° C. to 1200
A method for producing spherical leucite crystals through a step of heating to a temperature range of ° C. and a step of washing after the heating step.