JPH0451485B2 - - Google Patents

Description

[Detailed description of the invention]

FIELD OF THE INVENTION The present invention relates to microcrystalline synthetic flypontite and a method for producing the same. Conventional technology fraipontite is a
It has a chemical composition expressed as 8ZnO・2Al ₂ O ₃・5SiO ₂・11H ₂ O, and has a shell consisting of fibrous crystals, yellowish white,
It is known as silk luster, a mineral similar to asbestos,
This mineral is said to have been produced in a mine in Vieille-Montage, Belgium, but its origin is unknown, and as far as the present inventor is aware, there is no known example of its successful synthesis to date. Purpose of the Invention The present inventors have developed water-soluble silicates, water-soluble subliminal salts, water-soluble aluminum salts, and/or water-soluble aluminates in which the composition of SiO ₂ , ZnO, and Al ₂ O ₃ is within a certain range. When the precipitate formed is heated in the presence of moisture, if necessary,
It has been found that zinc phylosilicate or aluminum-containing zinc phylosilicate can be obtained which shares an X-ray diffraction pattern with the above-mentioned natural flypontite but has completely different properties. That is, an object of the present invention is to provide a microcrystalline synthetic flypontite and a method for producing the same. Another object of the present invention is to provide a synthetic flypontite having high whiteness and a large specific surface area, and a method for producing the same. Still another object of the present invention is to provide synthetic flypontite useful as a color developer for leuco dyes and a method for producing the same. Structure of the Invention According to the present invention, zinc phylosilicate or aluminum-containing zinc phylosilicate having a flypontite X-ray diffraction pattern, a Hunter whiteness of 80% or more, and a specific surface area of 100 m ² /g or more is produced. Microcrystalline synthetic flypontite is provided. According to the invention also 3 expressed as an oxide
A water-soluble silicate, a water-soluble zinc salt, and a water-soluble aluminum salt are reacted in an amount corresponding to 5 to 45 mol % of SiO ₂ , ₃₅ to 65 mol % of _ZnO , and 0 to 60 mol % of Al 2 O 3 in terms of component composition ratio. Provided is a method for producing a microcrystalline flypontite-type silicate mineral, which comprises heating the resulting precipitate in the presence of moisture, if necessary. Preferred Embodiments of the Invention The present invention will be described in detail below. Structure and Properties of Synthetic Flypontite The synthetic flypontite according to the present invention is mainly composed of zinc phyllosilicate or aluminum-containing zinc phylosilicate with a two-layer structure, and is composed of a tetrahedral layer of SiO ₄ and a tetrahedral layer of ZnO ₆ . The basic skeleton is a two-layer structure in which octahedral layers are combined in a layered manner, and a part of the Si in the SiO ₄ tetrahedron is replaced with Al, and corresponding to this valence, the ZnO ₆ octahedral structure is Some of the Zn is still
It has a structure in which Al is substituted. The basic chemical structure of this synthetic flypontite is given by the following formula (Zn _3-x Al _x ) (Si _2-x Al _x ) O ₅ (OH) ₄ ...(1), where x is 0 Values from 1.75 to 1.75, especially from 0.3 to 1.0. It is clear that naturally occurring flypontites have a value of x of approximately 0.65, whereas in the present invention the value of x can be varied over a fairly wide range. In the synthesis of flypontite, microcrystalline synthetic flypontite is likely to be produced within the range of the above-mentioned compositional formula, especially in a composition close to that of natural flypontite, but the three-component composition ratio expressed as an oxide is SiO ₂ 5
~40 mol%, ZnO35~65 mol%, and _{Al2O30 ~}
When the content is in the range of 60 mol%, a phyllosilicate mineral having a flypontite type microcrystalline structure can be obtained. The synthetic flypontite according to the present invention exhibits an X-ray diffraction pattern almost similar to that of natural flypontite, but is clearly distinguished from natural flypontite in that it is microcrystalline. The synthetic flypontite according to the present invention is
It generally has an X-ray diffraction pattern shown in Table A below. Section A Surface spacing dx (Å) Relative intensity I/I ₀ 8.4~6.4 40~70 3.9~3.5 40~70 2.7~2.6 100 2.5~2.4 50~80 1.6~1.5 50~80 Figure 1 of the attached drawings shows: 1 is an X-ray diffraction spectrum of microcrystalline synthetic flypontite according to the present invention. On the other hand, according to the 1974 ASTM card, the X-ray diffraction image of naturally occurring flypontite is as follows:
As shown in the table. Part B Surface spacing dx (Å) Relative intensity I/I ₀ 7.00 100 3.52 70 2.63 30 2.48 20 2.36 20 2.25 10 2.12 10 1.99 10 1.76 10 1.65 10 1.53 20 Comparing the two, in natural flypontite, The diffraction peak with the interplanar spacing d = 7.0 Å, that is, the diffraction peak with the planar index [001], is the strongest, and the basic two-layer structure is regularly stacked in the C-axis direction, whereas the microcrystal according to the present invention In the synthetic flypontite, the diffraction peak of plane index [001] is d
It is broad over a wide range of =8.4 to 6.4 Å, indicating that the crystals in the C-axis direction are well-developed and fine, and that there are parts where the interlayer positions are quite wide. The flypontite type zinc phylosilicate or aluminum-containing zinc phylosilicate according to the present invention is
In connection with this fine and loose crystal structure, it has an exceptionally high specific surface area for a two-layered phyllosilicate, with a BET specific surface area of 100 m ² /g or more, In particular, the value is large, reaching over 150 m ² /g. In addition, this flypontite type mineral is a synthetic product, does not contain impurities that cause coloration, and is microcrystalline, so it has excellent whiteness, with a Hunter whiteness of 80. % or more, especially 90% or more. The synthetic flypontite according to the present invention appears to have fine plate-like crystals, but the particle shape is irregular. This is a scanning electron micrograph showing the grain structure of the product shown in FIG. 2 of the accompanying drawings. The particle size of this synthetic flypontite varies over a fairly wide range, with the median diameter measured by centrifugal sedimentation generally ranging from 0.1 to 100 μm, particularly from 0.5 to 100 μm.
It is within the range of 20μm. Production method This microcrystalline flypontite has a three-component composition ratio expressed as an oxide: SiO ₂ 5 to 40 mol%;
Water-soluble silicates, water-soluble zinc salts, water-soluble aluminum salts and/or water-soluble aluminates in amounts corresponding to 5 to 60 mol% of _ZnO and 0 to 60 mol% of _Al2O3 are reacted in the presence of water. and heating the precipitate obtained if necessary in the presence of moisture. This reaction is easily carried out by the so-called double decomposition method. That is, the silica component is an alkali silicate such as sodium silicate, the ZnO component is a water-soluble zinc salt such as zinc chloride, zinc nitrate, zinc sulfate, etc., and when the alumina component is used, it is mixed with sodium aluminate and Alternatively, a water-soluble aluminum salt such as aluminum chloride or aluminum sulfate is used, and these are mixed in the presence of water to cause a reaction to occur by metathesis. In order to carry out this metathesis reaction homogeneously, a method is adopted in which the reaction is carried out while simultaneously adding silicate, zinc salt, or further aluminum salt and/or aluminate to water. The metathesis reaction is sufficient at room temperature, but at 95℃
It is of course possible to carry out the reaction under heating up to a certain degree.
The pH of the reaction system during simultaneous injection reaction is 5 to 10,
In particular, it is preferable to maintain it within the range of 6 to 9. Therefore, if necessary, acid or alkali is added to the reaction system to maintain the pH of the liquid within the above range. Due to the simultaneous injection, a precipitate of a compound having a composition approximately corresponding to the above-mentioned composition is formed, and it is recognized that this precipitate already exhibits a flypontite type X-ray diffraction pattern. It is generally preferred to heat-treat the mother liquor containing this precipitate in order to further develop the flypontite crystal structure. This heat treatment is generally 50
0.5 to 5 at temperatures from 70 to 95°C, especially
It is better to do it for hours. It should be noted here that if this treatment is carried out at a high temperature exceeding the above range, the generated precipitate tends to change into willemite, hemimorphite, etc., and as a by-product. After the heat treatment, the precipitate is separated, washed with water,
The product of the present invention is obtained by post-processing such as drying, crushing, and sieving. Applications The synthetic flypontite according to the invention has properties as a solid acid in connection with the fact that it is composed of microcrystalline zinc phyllosilicate or aluminum-containing zinc phyllosilicate. In addition, this material has a high surface activity, with a specific surface area of 100 m ² /g or more.
Moreover, it has excellent whiteness. Due to these properties, the product according to the invention:
When it comes into contact with various leuco dyes, it exhibits outstanding coloring performance and can be advantageously used as a color developer for pressure-sensitive paper or as an auxiliary agent for organic color developers. The invention is illustrated by the following example. Test method The test method for each item in this specification was as follows: 1. X-ray diffraction In this example, an
2125D1, counting device 5071) was used. The diffraction conditions are as follows. Target Cu Filter Ni Detector SC Voltage 35KVp Current 15mA Count full scale 8000c/s Time constant 1sec Scanning speed 2゜/min Chart speed 2cm/min Radiation angle 1゜ Slit width 0.3mm Illumination angle 6゜2 Hunter whiteness In this example, an automatic reflectometer model TR-600 manufactured by Tokyo Denshoku Co., Ltd. was used. 3 BET specific surface area [SA] The specific surface area of each powder was measured according to the so-called BET method using nitrogen gas adsorption. For details, please refer to the following literature. S. Brunauer, PHEmmett, E. Teller, J. Am.
Chem.Soc, Vol. 60, 309 (1938) In this specification, the specific surface area is measured by drying the surface area to 150°C in advance.
Transfer to a weighing bottle, dry for 1 hour in a constant temperature dryer at 150°C, and immediately weigh accurately. This sample was placed in an adsorption sample tube and heated to 200℃, degassed until the degree of vacuum within the adsorption sample tube reached 10 ^-4 mmHg, and after cooling, the adsorption sample tube was placed in liquid nitrogen at approximately -196℃. , pN ₂ /p ₀ = 0.05 to 0.30 (PH ₂ : nitrogen gas pressure, p ₀ = atmospheric pressure at the time of measurement) The adsorption amount of N ₂ gas is measured at 4 to 5 points. Then, the adsorption amount of _N2 gas after subtracting the dead volume is 0℃,
Convert it to the adsorption amount at 1 atm and substitute it into the BET formula to get Vm
[cc/g] (indicating the amount of nitrogen gas adsorption required to form a monomolecular layer on the sample surface) is determined. Specific surface area SA
=4.35×Vm [m ² /g] Example 1 No. 3 sodium silicate (SiO ₂ : 22.0%, Na ₂ O: 7.0
%) 109g and sodium hydroxide 94g (NaOH content:
Dissolve 2.35 mol) in water to make the total amount 1, and use this as Solution A (SiO ₂ min: 0.4 mol). On the other hand, dissolve 95 g of zinc chloride (anhydrous salt) and 97 g of aluminum chloride (hexahydrate) in water to make a total volume of 1, and use this as solution B (ZnO content: 0.7 mol, Al ₂ O ₃ min: 0.2 mol). . Pour 1 of water into the beaker of 5 and stir while stirring.
Solution A and solution B were each injected simultaneously at a rate of about 25 c.c./min. After the addition was completed, the pH of the reaction solution was 6.9. After further stirring and aging for 30 minutes, the mixture was heated on a water bath at 85 to 90°C for 2 hours. The reaction solution was filtered under suction, washed with water, and dried at 110°C. The resulting cake was pulverized using a small impact pulverizer (sample mill), and coarse particles were removed by elutriation to obtain a fine white powder. Examples 2 to 6 In Example 1, solutions A and B were prepared by changing the amounts of No. 3 sodium silicate, sodium hydroxide, zinc chloride, and aluminum chloride as shown below, and the rest was carried out in exactly the same manner. I did it.

[Table] Example 7 No. 1 Sodium Silicate (SiO ₂ : 35.0%, Na ₂ O:
17.5%) 77g and sodium hydroxide 24g (NaOH
0.6 mol) in water to make a total volume of 1,
This is called liquid C (SiO ₂ minutes: 0.45 mol). Next, dissolve 216 g of zinc sulfate (heptahydrate) in water to bring the total amount to 1, and add this to Solution D (ZnO content: 0.75 mol).
shall be. Furthermore, sodium aluminate solution (Al ₂ O ₃ :
Dilute 75g of 20.5%, Na ₂ O: 19.5%) in water to make a total volume of 1, and add this to Solution E (Al ₂ O ₃ minutes: 0.15 mol)
shall be. 1 of water was placed in a beaker No. 5, and while stirring, liquids C, D, and E were each added at the same time at a rate of 25 c.c./min. The pH of this reaction solution after the addition is complete
was 7.0. Suction the reaction solution, wash with water,
Dry at 110°C. The resulting cake was pulverized using a small impact pulverizer, and coarse particles were removed by elutriation to obtain a fine white powder. 3 of the powders obtained in Examples 1 to 7
The component composition ratio, Hunter whiteness, specific surface area, and X-ray diffraction analysis results are listed in Table 1.

【table】 [Brief explanation of the drawing]

Figure 1 shows the Cu of flypontite type aluminium-containing zinc phylosilicate according to Example 1 of the present invention.
- This is an X-ray diffraction spectrum using Kα rays. FIG. 2 is a scanning electron micrograph (magnification: 10,000 times) showing the particle structure of flypontite-type aluminum-containing zinc phyllosilicate according to Example 1 of the present invention.

Claims (1)

[Claims] 1. A fine powder made of zinc phylosilicate or aluminum-containing zinc phylosilicate having a flypontite-type X-ray diffraction pattern, a Hunter whiteness of 80% or more, and a specific surface area of 100 m ² /g or more. Crystalline synthetic flypontite. 2 The composition ratio of the three components expressed as oxides,
_SiO2 5-45 mol% _, ZnO35-65 mol% and _Al2O30
A water-soluble silicate, a water-soluble zinc salt, a water-soluble aluminum salt and/or a water-soluble aluminate corresponding to ~60 mol% are reacted in the presence of water, and if necessary, the formed precipitate is allowed to react in the presence of water. A method for producing a microcrystalline flypontite-type silicate mineral, which comprises heating.