JPH05147930A - Production of platy particle based on calcium aluminum oxide-carbonate-hydrate and its fired product - Google Patents

Abstract

PURPOSE:To improve reinforcing property by mixing an aq. NaAlO2 soln. with Ca(OH)2 in a specified molar ratio, heating the mixture to a prescribed temp. or above, blowing gaseous CO2 and depositing platy particles. CONSTITUTION:Ca(OH)2 is added to an aq. NaAlO2 soln. by 0.5-4 mol per 1 mol NaAlO2 and they are mixed and heated to 240 deg.C under high-speed stirring. Gaseous CO2 is then blown and the compds. are brought into a reaction to deposit platy particles. This deposit is separated by filtration, dehydrated, washed and dried to obtain platy particles based on calcium.aluminum oxide.cearbonate.hydrate and having about 2-10mum major axis size of the bottoms and about 0.1-0.3mum thickness. Fired platy particles of calcium-aluminum oxide are obtd. by heating the above-mentioned platy particles.

Description

Detailed Description of the Invention

[0001]

INDUSTRIAL APPLICABILITY The present invention relates to plate-like particles useful as fillers, which are often used as fillers and reinforcing agents for rubbers and plastics, paints and papermaking in various industrial fields, especially calcium aluminum oxide. The present invention relates to the production of plate-shaped particles mainly composed of a substance, a carbonate and a hydrate.

[0002]

2. Description of the Related Art When classifying fillers by chemical composition, they are classified into inorganic compounds such as oxides, hydroxides, carbonates, silicates and carbon, and organic compounds such as wood flour, nylon fibers, aromatics and polyamide fibers. Divided * ¹ .

[0003] Further, when classified by the manufacturing method, there are classified natural products such as calcium carbonate (heavy carbon), magnesium silicate (talc), aluminum silicate (kaolinite), and the like.
It can be classified into compound products such as calcium carbonate (light carbon), calcium silicate, and aluminum hydroxide, and thermally decomposed products such as carbon black and magnesium oxide * ² .

As described above, a large number of fillers having various chemical compositions and manufactured by various methods have been developed and used according to the purpose. Among the various effects obtained by adding the filler to rubber, plastic, etc., there are reinforcement, function addition and the like. The main factors that influence these performances are the particle size of the filler, the shape of the particle,
Considered to be a chemical composition. For example, reinforcing effect (flexural modulus,
Bending strength, heat deformation temperature, dimensional stability, etc.) depend largely on the shape of the particles, and it is said that a filler having an anisotropic shape such as a plate shape or a needle shape is preferable. On the other hand, the functionalization (retardation and flame retardancy) largely depends on the chemical composition, and it is said that a filler having a chemical composition that generates a large amount of water or carbon dioxide gas such as hydroxide or carbonate is preferable. Further, it is said that a filler having a layered shape, a plate shape or a fibrous shape, or a heavy filler is good for imparting a vibration damping function.
* ³ .

At present, as plate-like and layered fillers, talc (hydrous magnesium silicate), aluminum hydroxide,
Magnesium hydroxide, kaolinite (aluminum silicate), mica (aluminum silicate) and the like are widely used in plastics, rubber, papermaking, paints, cosmetics and the like. Here, since aluminum hydroxide and kaolin clay do not have a very large aspect ratio, they do not exhibit significant characteristics in terms of composite effects such as rigidity * ¹ . It is talc and mica with large aspect ratios that fully exhibit the plate-like characteristics in the combined effect * ¹ . It is only necessary to increase the aspect ratio to emphasize the combined effect, but talc and mica cannot exceed the level of those currently manufactured due to the manufacturing process restrictions of crushing and classifying natural minerals. It looks difficult * ¹ .

Quotations * 1) Hiroshi Yui, Material Design for Composite Plastics, Second Edition, (Plastic Age, 1985) * 2) Japan Rubber Association Rubber Technical Committee, 11th Subcommittee, White Filler Special Committee, Filler Handbook, (Taiseisha, 1985) * 3) Isoma Soma, Polyfile, 28, [6], 28
(1991)

[0007]

DISCLOSURE OF THE INVENTION The present invention makes use of the characteristics of a plate and is used for plastics, rubber, paper, paints, etc.
It is an object of the present invention to produce a synthetic filler, which is expected to have a great improvement in performance such as reinforcing effect, retardation / flame retardancy, vibration damping, surface smoothness, and gloss.

[0008]

Means for Solving the Problems The method for producing plate-like particles containing calcium aluminum oxide / carbonate / hydrate as a main component of the present invention is as follows. Calcium hydroxide is mixed in an amount of 0.5 to 4 mol and heated to 40 ° C. or higher to blow carbon dioxide gas to precipitate plate-like particles.

By subjecting the plate-like particles obtained by the above method to heat treatment, plate-like particles mainly composed of amorphous or calcium aluminum oxide can be obtained.

In the present invention, calcium hydroxide is added to an aqueous solution of sodium aluminate to cause reaction, and after heating, an appropriate amount of carbon dioxide gas is blown. It is necessary to add 0.5 to 4 mol of calcium hydroxide to 1 mol of sodium aluminate. When calcium hydroxide is not added at all, plate-like particles do not precipitate, so the lower limit of the amount of calcium hydroxide added is the amount at which plate-like particles can be precipitated.
Generally, the amount is 0.5 mol or more, preferably 1 mol to 3
It is a mole. If the amount of calcium hydroxide added deviates from the above range, the proportion of fine particles other than plate-like particles mixed in will increase, as seen in the SEM photograph of Comparative Example 1 described later.

In the present invention, it is necessary to add a predetermined amount of calcium hydroxide to an aqueous solution of sodium aluminate and then heat it to 40 ° C. or higher, preferably 50 ° C. or higher to blow carbon dioxide gas to carry out the reaction. If this temperature is too low, as shown in the SEM photograph of Comparative Example 2, the plate-like shape is deteriorated. The upper limit of the heating temperature is not particularly limited, but generally 100 ° C or lower is suitable.

When carbon dioxide gas is blown in, particles of calcium aluminum hydrate disappear, and plate-like particles begin to precipitate gradually. Further, when the carbon dioxide gas is continuously blown, the precipitated particles are further carbonated to form acicular calcium carbonate (aragonite), so that the carbon dioxide gas blow is stopped before the reaction is completed. The appropriate amount of carbon dioxide gas injection varies depending on the sodium aluminate / calcium hydroxide molar ratio, the heating temperature, the shape of the reaction vessel, the carbon dioxide gas injection method, the stirring method of the reaction liquid, etc. confirm.

As the carbon dioxide gas, only carbon dioxide gas may be blown or a mixed gas containing carbon dioxide gas may be blown. By the above reaction, plate-like particles mainly composed of calcium aluminum oxide / carbonate / hydrate having a bottom major axis of 2 to 10 μm and a thickness of 0.1 to 0.3 μm are produced.

When the obtained plate-like particles are heat-treated to be amorphous, and further heated at a high temperature, a peak of calcium aluminum oxide (Ca ₁₂ Al ₁₄ O ₃₃ ) appears (a part of CaO peak is also present). Seen). Both the particles mainly composed of this amorphous material and the particles mainly composed of calcium / aluminum oxide maintain the plate shape before the heat treatment,
Similarly, it is useful as a filler. Heat treatment is generally 3
It is preferable to carry out at a temperature of 00 to 900 ° C.

[0015]

EFFECTS OF THE INVENTION According to the present invention, calcium aluminum oxide, carbonate and hydrate can be easily added by adding an appropriate amount of calcium hydroxide to an aqueous solution of sodium aluminate and blowing an appropriate amount of carbon dioxide gas at an appropriate temperature. Plate-like particles mainly composed of a substance are obtained. By using these plate-like particles, development of plastics, rubbers, papers, paints or new materials having new physical properties can be expected sufficiently.

[0016]

【Example】

Example 1 Aqueous sodium aluminate solution (1/6 mol / liter,
(25 ° C) 1/3 mol of calcium hydroxide was added to 2 liters, and the mixture was stirred with a high-speed emulsifying / dispersing machine for 1 hour to 70 to 7
Heat to 5 ° C. While stirring this with a high-speed emulsifier / disperser, carbon dioxide gas (about 0.1 liter / min) is blown therein for 30 minutes to react. The product was washed with water, filtered and dehydrated with a filter, and dried at about 100 ° C. using an electric dryer to obtain sample No. 1 plate-like particles are obtained.

FIG. 1 shows the sample No. The observation photograph by SEM of 1 is shown. The scale below the photo is full scale 10μ.
m represents 1 μm on a scale. Further, FIG. 1
X-ray diffraction pattern of mainly Ca ₄ Al ₂ CO ₉ / 11H
₂ O is shown.

Example 2 Aqueous sodium aluminate solution (1/3 mol / liter,
25 ° C.) 1 mol of calcium hydroxide is added to 2 liters, and the mixture is stirred at a high speed emulsifying / dispersing machine for 1 hour to 70-75.
Heat to ℃. While stirring this with a high-speed emulsification / dispersion machine, carbon dioxide gas (about 0.1 liter / minute) is blown therein for 90 minutes to react. Thereafter, in the same manner as in Example 1, sample N
o. 2 plate-like particles are obtained.

FIG. 2 shows the sample No. The observation photograph by the SEM photograph of 2 is shown. The scale below the photo is full scale 10
μm and 1 μm on a scale. In addition, FIG.
o. Mainly Ca with 2 X-ray diffraction pattern ₄ Al ₂ CO ₉ · 1
1H ₂ O.

Example 3 Aqueous sodium aluminate solution (1/6 mol / liter,
(25 ° C.) 5/6 mol of calcium hydroxide was added to 2 liters, and the mixture was stirred with a high speed emulsifying / dispersing machine for 1 hour to 70 to 7
Heat to 5 ° C. While stirring this with a high-speed emulsifying / dispersing machine, carbon dioxide gas (about 0.1 liter / min) is blown therein for 45 minutes to react. Thereafter, in the same manner as in Example 1, sample N
o. 3 plate-like particles are obtained.

FIG. 3 shows the sample No. The observation photograph by the SEM photograph of 3 is shown. The scale below the photo is full scale 10
μm and 1 μm on a scale. Further, FIG. 11 shows the sample N
o. X-ray diffraction pattern of 3 is mainly 3CaO ・ Al ₂ O ₃・
3CaCO · 32H ₂ O and Ca ₄ Al ₂ CO ₉ · 11H ₂ O.

Example 4 Aqueous sodium aluminate solution (1/6 mol / liter,
25 ° C.) 1 mol of calcium hydroxide is added to 2 liters, and the mixture is stirred at a high speed emulsifying / dispersing machine for 1 hour to 70-75.
Heat to ℃. While stirring this with a high-speed emulsifying / dispersing machine, carbon dioxide gas (about 0.1 liter / min) is blown therein for 45 minutes to react. Thereafter, in the same manner as in Example 1, sample N
o. 4 plate-like particles are obtained.

FIG. 4 shows the sample No. The observation photograph by the SEM photograph of 4 is shown. The scale below the photo is full scale 10
μm and 1 μm on a scale. FIG. 12 shows the sample N
o. The X-ray diffraction pattern of 4 is mainly 3CaO ・ Al ₂ O ₃・
3CaCO · 32H ₂ O and Ca ₄ Al ₂ CO ₉ · 11H ₂ O.

Comparative Example 1 Aqueous sodium aluminate solution (1/6 mol / liter,
(25 ° C) 5/3 mol of calcium hydroxide was added to 2 liters, and the mixture was stirred with a high-speed emulsifying / dispersing machine for 1 hour to 70 to 7
Heat to 5 ° C. While stirring this with a high-speed emulsifier / disperser, carbon dioxide gas (about 0.1 liter / min) is blown for 60 minutes to react. Thereafter, in the same manner as in Example 1, sample N
o. 5 particles are obtained.

FIG. 5 shows the sample No. The observation photograph by the SEM photograph of 5 is shown. The scale below the photo is full scale 10
μm and 1 μm on a scale. It can be seen that a relatively large amount of fine particles other than the plate-like particles are mixed.

Further, FIG. 13 shows sample No. X-ray diffraction pattern of 5 is mainly 3CaO ・ Al ₂ O ₃・ 3CaCO ・ 32H
₂ O, Ca ₄ Al ₂ CO ₉ / 11H ₂ O, and Ca (O
H) _{2 is} also included.

Example 5 Aqueous sodium aluminate solution (1/6 mol / liter,
(25 ° C) 1/2 mol of calcium hydroxide is added to 2 liters, and stirred for 50 minutes with a high-speed emulsifying / dispersing machine for 50 to 5
Heat to 5 ° C. While stirring this with a high-speed emulsifying / dispersing machine, carbon dioxide gas (about 0.1 liter / min) is blown therein for 45 minutes to react. Thereafter, in the same manner as in Example 1, sample N
o. 6 plate-like particles are obtained.

FIG. 6 shows the sample No. The observation photograph by the SEM photograph of 6 is shown. The scale below the photo is full scale 10
μm and 1 μm on a scale. In addition, FIG.
o. The X-ray diffraction pattern of No. 6 was mainly 3CaO ・ Al ₂ O ₃・
3CaCO · 32H ₂ O and Ca ₄ Al ₂ CO ₉ · 11H ₂ O.

Comparative Example 2 Aqueous sodium aluminate solution (1/6 mol / liter,
(25 ° C) Add 1/2 mol of calcium hydroxide to 2 liters and stir for 35 hours with high speed emulsifying / dispersing machine for 35-4
Heat to 0 ° C. While stirring this with a high-speed emulsifying / dispersing machine, carbon dioxide gas (about 0.1 liter / min) is blown therein for 45 minutes to react. Thereafter, in the same manner as in Example 1, sample N
o. 7 particles are obtained.

FIG. 7 shows the sample No. The observation photograph by the SEM photograph of 7 is shown. The scale below the photo is full scale 10
μm and 1 μm on a scale. It can be seen that the plate-like morphology of the particles has deteriorated. Further, FIG. X of 7
Mainly 3CaO / Al ₂ O ₃ / 3CaCO in line diffraction pattern
32H ₂ O and Ca ₄ Al ₂ CO ₉ / 11H ₂ O are shown.

Example 6 Aqueous sodium aluminate solution (1/3 mol / liter,
(25 ° C) 5/3 mol of calcium hydroxide was added to 2 liters, and the mixture was stirred with a high-speed emulsifying / dispersing machine for 1 hour to 70 to 7
Heat to 5 ° C. While stirring this with a high-speed emulsification / dispersion machine, carbon dioxide gas (about 0.1 liter / minute) is blown therein for 90 minutes to react. The product is washed with water, filtered, dehydrated by a filter, and dried at about 100 ° C. using an electric dryer. Furthermore, heat treatment at 400 ° C was performed in an electric furnace to obtain sample N
o. 8 plate-like particles are obtained.

FIG. 8 shows the sample No. The observation photograph by the SEM photograph of 8 is shown. The scale below the photo is full scale 10
μm and 1 μm on a scale. 16 shows the sample N
o. In the X-ray diffraction pattern of No. 8, peaks do not appear so much, which indicates that it is mainly amorphous.

[Brief description of drawings]

FIG. 1 is a sample No. 2 is an SEM observation photograph showing the particle structure of No. 1;

2] Sample No. 2 is an SEM observation photograph showing the particle structure of No. 2;

3] Sample No. 3 is an SEM observation photograph showing the grain structure of Example 3.

4] Sample No. 4 is an SEM observation photograph showing the particle structure of Example 4.

5] Sample No. 5 is an SEM observation photograph showing the particle structure of Example 5.

6 is a sample No. 6 is an SEM observation photograph showing the particle structure of No. 6;

7] Sample No. 7 is an SEM observation photograph showing the particle structure of Example 7.

8] Sample No. 8 is an SEM observation photograph showing the particle structure of Example 8.

9] Sample No. 2 is an X-ray diffraction pattern of 1.

10] Sample No. 2 is an X-ray diffraction pattern of No. 2.

11] Sample No. 3 is an X-ray diffraction pattern of Sample No. 3.

FIG. 12: Sample No. 4 is an X-ray diffraction pattern of No. 4.

13] Sample No. 5 is an X-ray diffraction pattern of Sample No. 5.

14] Sample No. 6 is an X-ray diffraction pattern of No. 6.

15 is a sample No. 7 is an X-ray diffraction pattern of No. 7.

16] Sample No. 8 is an X-ray diffraction pattern of No. 8.

Claims (2)

[Claims] 1. Mixing an aqueous solution of sodium aluminate with calcium hydroxide in an amount of 0.5 to 4 mol per mol of sodium aluminate and heating to 40 ° C. or higher to blow carbon dioxide gas to form plate-like particles. A method for producing plate-like particles mainly composed of calcium aluminum oxide / carbonate / hydrate, characterized by precipitating. 2. A method for producing calcined plate-like particles, which comprises subjecting the plate-like particles obtained in claim 1 to heat treatment to be amorphized or made into calcium aluminum oxide.