JPH0569769B2 - - Google Patents

Description

[Detailed description of the invention]

This invention is a hectorite-type smectite that swells in water, has excellent gel-forming ability, ion-exchange ability, film-forming ability, etc., and also has special functions such as inclusion of metal polynuclear hydroxide ions and various organic substances between layers. This invention relates to a swellable silicate having a structure similar to , and a method for producing the same. Smectite is a member of phyllosilicates that has a three-layer structure of the Sandermansch type, consisting of two silica tetrahedral layers sandwiching a magnesium octahedral layer or an aluminum octahedral layer, and has cation exchange ability in water. Furthermore, it is a clay mineral that has the unique property of absorbing water between its layers and swelling. In nature, 2- contains trivalent aluminum in the octahedral layer.
Montmorillonite, an octahedral smectite,
Beidellite and hectorite and saponite, which are 3-octahedral smectites containing divalent magnesium in the octahedral layer, are known, but they are not produced in large quantities in Japan for industrial use. is only bentonite containing montmorillonite. A montmorillonite product extracted from this bentonite has been commercialized as pure smectite, and it is expected that its swelling and gel properties will be utilized to develop applications in fields such as cosmetics, pharmaceuticals, and water-based paints. Pure montmorillonite is manufactured by extracting it from a dilute aqueous bentonite dispersion solution of about 1 to 2%, which requires considerable refining costs such as drying costs, and is commercially available at an extremely high price.Moreover, since it is a natural product, the raw material bentonite is The characteristics of pure montmorillonite products tend to vary considerably due to differences in collection location and collection time, and demand for it is quite limited. Furthermore, because material properties such as chemical composition, structure, defects, and impurities vary widely, it is almost impossible to control the properties, making it unsuitable as a highly functional precision material. On the other hand, sodium-type tetrasilicon mica (JP-A-51-24598) products, which are synthetic swelling fluorinated mica-based minerals, are commercially available as gelling agents, but the mica structure originally makes it difficult to swell in water. Therefore, its swelling properties in water are inferior to commercially available pure smectite products, and its demand is still limited. The purpose of the present invention is to provide an industrially satisfactory engineered precision material that does not have the drawbacks of pure montmorillonite products extracted from naturally occurring bentonite, and which is even higher than pure montmorillonite products or sodium-type tetrasilicon mica products. The object of the present invention is to provide a functional synthetic swellable silicate and a technology for producing the same. As a result of many years of intensive research into the synthesis of swellable silicates with excellent cation exchange ability or gel-forming ability, the present inventors have discovered a structure similar to hectorite-type smectite, which is rarely produced naturally in Japan. has extremely excellent gel-forming ability,
The present invention led to the invention of a new synthetic swellable silicate having special functions such as ion-exchange ability and film-forming ability, and a method for producing the same. That is, this invention has the general formula [Si ₈ (M _6-ab Mg _a Li _b ) O ₂₀ (OH) _4-c F _c ] ^b-・A ^y+ _b/y
() (The values of a, b, c and y in the formula are 0≦a<
6,0<b≦2,0≦c≦4 and 1≦y≦2, M is Co, Ni, Zn, Cu, Fe, Mn, Pb, Cd
At least one divalent heavy metal ion selected from divalent heavy metal ions such as A is at least one cation selected from the group consisting of alkali metal ions, alkaline earth metal ions, ammonium ions, and alkylammonium ions. The present invention provides a synthetic swellable silicate having a structure similar to hectorite-type smectite represented by According to McEwan, the model chemical formula of hectorite, which belongs to the 3-octahedral smectite group, is ()
(Montmorillonite minerals)
by DMCMacEwan, The X-ray
identification and crystal structures of clay
minerals edited by G.Brown, Mineralogical
society, London, 1972, pp. 143-207).

[C] Here, M ⁺ is a monovalent exchangeable cation that exists between the layers. Hectorite belongs to the tri-octahedral smectites, with silicon located in the tetrahedral layer and magnesium in the octahedral layer. It is thought that the layer charge of hectorite is generated when part of the divalent magnesium in the octahedral layer is replaced with monovalent lithium, and cations are formed between the layers to electrically balance the negative charge. Contains. In the synthetic swellable silicate of the present invention represented by the general formula (), all or part of the magnesium in the octahedral layer in the general formula () is cobalt, nickel, zinc, copper, iron, manganese, lead, or cadmium. There are also structures in which the hydroxyl groups are substituted with divalent heavy metals, or in which some or all of the hydroxyl groups are substituted with fluorine. Such hectorite-type smectites containing large amounts of heavy metals are hardly known in nature, and the synthetic swellable silicate of the present invention is considered to be a new smectite. In the synthetic swellable silicate of the present invention, the layer charge is 2 in the octahedral layer.
It is thought to be generated by the substitution of valent heavy metals or magnesium with monovalent lithium, ()
It can be inferred that it has a structure similar to hectorite shown by the formula. The total amount of heavy metals, magnesium and lithium in the octahedral layer in the synthetic swellable silicate of the present invention is structurally 6 as shown in the general formula ().
However, as long as the preparation composition has a value of around 6, the present invention can be achieved even if the total amount is made slightly larger or smaller, and the value is 5.
A range of 7 to 7 is acceptable. If more lithium is added than necessary, the lithium that cannot fit into the octahedral layer may be incorporated into the structure as exchangeable cations. A method for achieving the present invention will be described below. The method for producing a synthetic swellable silicate of the present invention consists of the following steps. First, a homogeneous composite precipitate containing silicon, divalent heavy metals, and optionally magnesium is prepared, and second, this homogeneous composite precipitate is mixed with water, lithium ions, and exchangeable cations or fluorine ions if necessary. is added to form a starting material slurry, thirdly, the slurry is subjected to a hydrothermal reaction to produce a synthetic swellable silicate, and fourthly, this hydrothermally reacted product is dried and pulverized to produce the product of the present invention. can be obtained. In the first step, a homogeneous solution obtained by mixing silicic acid, a divalent heavy metal salt, and if necessary, a magnesium salt is precipitated with an alkaline solution, and by-product solutes are removed by filtration and water washing to obtain a homogeneous composite precipitate. be adjusted. A homogeneous solution containing silicic acid and a divalent heavy metal salt and, if necessary, a magnesium salt can be prepared by mixing the silicic acid solution and a divalent heavy metal salt aqueous solution and adding an aqueous magnesium salt solution if necessary, or by directly adding divalent heavy metal salt to the silicic acid solution. Obtained by dissolving a heavy metal salt and, if necessary, a magnesium salt. The mixing ratio of silicic acid, divalent heavy metal salt, and magnesium salt is determined by selecting the values of a and b within a range that satisfies the general formula (). The value of b is between 0 and 2, but usually preferred values are between 0.5 and 2.
It is between 1.0. The synthetic swellable silicate of the present invention is produced even when a=0 and no magnesium is contained. By determining the values of a and b, the value of divalent heavy metal is given by 6-a-b. It is preferable that the charging composition satisfies the general formula (),
The synthetic swellable silicate of the present invention can be produced even if the values of the amount of divalent heavy metals, the amount of magnesium (a), and the amount of lithium (b) are slightly varied from the calculated values,
A total metric of the above three values is allowed between 5 and 7. Silicic acid solution is made by mixing sodium silicate and mineral acid,
Obtained by making the pH of the liquid acidic. As the sodium silicate, any of commercially available No. 1 to No. 4 water glass and sodium metasilicate can be used. Nitric acid, hydrochloric acid, sulfuric acid, etc. are used as mineral acids. When mixing sodium silicate and mineral acid,
If the amount of mineral acid is small, gelation often occurs, so it is necessary to select the ratio of sodium silicate and mineral acid so that the pH of the liquid is 5 or less. Divalent heavy metal salts are cobalt,
You can choose from chlorides, sulfates, nitrates, etc. of nickel, zinc, copper, iron, manganese, lead, cadmium, etc. As long as the value satisfies the composition of the general formula (), not only one type of heavy metal but also any combination of two or more types can be selected, and the composition can be designed according to the application. If necessary, it is also possible to add a magnesium salt, which can be selected from magnesium chloride, magnesium sulfate, magnesium nitrate, and the like. Next, a homogeneous solution containing silicic acid and a divalent heavy metal salt or, if necessary, a magnesium salt, and an alkaline solution are mixed at room temperature to obtain a homogeneous composite precipitate. As the alkaline solution, sodium hydroxide solution, potassium hydroxide solution, aqueous ammonia, etc. are used. It is desirable to select the amount of alkaline solution such that the pH after mixing is 10 or higher. When the above-mentioned homogeneous solution and alkaline solution are mixed, the homogeneous solution may be dropped into the alkaline solution to cause precipitation, or the reverse order may be used. A homogeneous composite precipitate can also be obtained by instantaneously mixing both liquids. Stirring is not particularly required during mixing, but stirring is absolutely prohibited. Next, filtration and washing with water are repeated to sufficiently remove by-product electrolytes. These homogeneous composite precipitates containing heavy metals already have a low-crystalline smectite-like structure as determined by X-ray powder diffraction, and therefore, in the third step, hydrothermal treatment at a relatively low temperature and for a short period of time is effective. It is presumed that the synthetic swellable silicate of the present invention having the characteristics is produced. Furthermore, since the homogeneous composite precipitate often incorporates cations during precipitation, it is not necessary to particularly add exchangeable cations in the second step. The starting material slurry for the second step is prepared by adding a lithium hydroxide aqueous solution and, if necessary, a cationic hydroxide, fluoride, or a mixed aqueous solution thereof to the homogeneous composite precipitate obtained in the first step. Adjusted by adding hydrogen acid. For the hydrothermal reaction in the third step, the starting material composition slurry obtained in the second step is charged into an autoclave.
The reaction is carried out at a temperature of 100°C to 350°C to form the synthetic swellable silicate of the present invention. Although stirring is not particularly required during the reaction, stirring is absolutely prohibited. In general, the higher the reaction temperature, the faster the reaction rate, and the longer the reaction time, the better the crystal formation, but at a reaction temperature of 200°C and a reaction pressure of 15.9 kg/cm ² , a reaction time of 2 hours is sufficient. In the fourth step, after the completion of the hydrothermal reaction in the third step, the contents of the autoclave are taken out and heated to a temperature above 60℃.
The final product is obtained by drying at a temperature below 200°C and grinding. The novel synthetic swellable silicate produced by carrying out the present invention was determined by X-ray diffraction, differential thermal analysis, infrared absorption spectrum, chemical analysis, cation exchange capacity (CEC), viscosity properties, etc. can be evaluated. The novel synthetic swellable silicate of the present invention is Cu-Kα
It can be seen that the diffraction angle (2θ) when using a line normally appears between 60.3 degrees and 61.2 degrees for (35,06) of the (hk) reflection, indicating that it is a 3-octahedral smectite. The X-ray diffraction pattern is similar to that of hectorite, but the peaks are generally somewhat broader in many cases. Usually 60~ in aqueous solution
It exhibits a high cation exchange capacity of 120 milliequivalents/100g, or exhibits excellent swelling and dispersibility in water, produces a colored aqueous sol or gel corresponding to the type of heavy metal, and has thixotropic properties. It is extremely useful as an additive for water-soluble paints, ceramic raw materials, catalysts, etc., slurry stabilizers, thickeners, binders, suspension stabilizers, thixotropy imparting agents, etc. Since the novel synthetic swellable silicate of the present invention essentially contains divalent heavy metals, it can be used for purposes such as sterilization, antibacterial, and disinfection. In addition, since the structure contains heavy metals, the catalyst
It is useful as a catalyst carrier, and can also form interlayer complexes with various metal polynuclear hydroxide ions and be used as new catalysts, catalyst carriers, adsorbents, etc.
Furthermore, it can also be used as a lipophilic clay by forming an organic compound composite. It is also useful as a raw material for sensors, electromagnetic shielding agents, semiconductor materials, etc. by turning it into ceramics by firing. Next, an example will be given and explained. Example 1 Put 400 ml of water into the beaker from 1 and add a No. 3 water glass (SiO ₂ 28%, Na ₂ O 9%, molar ratio 3.22).
Dissolve 86 g and add 23 ml of 16N nitric acid at once while stirring to obtain a silicic acid solution. Next, add 28 g of magnesium chloride first grade reagent (98% purity) and cobalt chloride hexahydrate special grade reagent (99% purity) to 100 ml of water.
A homogeneous mixed solution of silicic acid-cobalt salt-magnesium salt prepared by adding 32.1 g of dissolved solution to the silicic acid solution was added dropwise to 400 ml of 2N sodium hydroxide solution over 5 minutes with stirring. The reaction homogeneous composite precipitate immediately obtained was filtered, thoroughly washed with water, and treated with lithium hydroxide monohydrate special grade reagent (purity 98
Add 30 ml of an aqueous solution containing 1.47 g of %) to form a slurry, and transfer to an autoclave. 15.9Kg/ ^cm2 ,
React at 200°C for 2 hours. After cooling, the reaction product is taken out, dried at 80°C, and then crushed using a grinder. This product contains cobalt as M, a=2.7,
It corresponds to b = 0.7, c = 0, contains sodium as an exchangeable cation, and its cation exchange capacity is 86
It was milliequivalent/100g. The X-ray powder diffraction pattern is 3
-It shows a pattern similar to hectorite, which is an octahedral smectite, but the overall peak is broad, and the d value of the (35,06) reflection peak is
It was 1.522 Å. The color of the powder is light purple;
The 2% aqueous dispersion formed a pale purple translucent solid gel and exhibited extremely strong cutisotropy. Example 2 The same procedure as in Example 1 was carried out except that the amounts of raw materials charged were as follows. No. 3 water glass 86g Cobalt chloride hexahydrate special grade reagent 64g Lithium hydroxide monohydrate special grade reagent 1.5g The obtained product has a purple color and contains cobalt as M, a=0, b=0.7, c =0,
The exchangeable cation was sodium, and the cation exchange capacity was 72 meq/100g. The X-ray powder diffraction pattern was similar to the pattern of the inventive product of Example 1, and the d value of the (35,06) reflection peak was 1.527 Å. The 2% aqueous dispersion formed a purple translucent thixotropic gel. A 2.5% aqueous dispersion was prepared using the products of the present invention obtained in Examples 1 and 2, the pure montmorillonite product Knipia F, and a commercially available synthetic sodium tetrasilicon mica product as an aqueous dispersant. Rheological properties are rotational viscometer
The results measured with a Fann VG meter are shown in the table.

[Table] As is clear from the table, the aqueous dispersion of the product of the present invention containing cobalt obtained in Example 1 and Example 2 is the commercially available pure montmorillonite product Knipia F.
It can be seen that it has extremely high viscosity, yield value, and gel strength, has strong thixotropy, and has excellent performance as a gelling agent for aqueous systems, compared to aqueous dispersions of synthetic sodium tetrasilicon mica products. Example 3 The same procedure as in Example 1 was carried out except that the amount of raw materials charged was as follows. No. 3 water glass 86g Nickel chloride () hexahydrate special grade reagent (purity 98
%) 64.1g Lithium hydroxide monohydrate special grade reagent 1.26g 10% hydrofluoric acid solution 10ml The obtained product has a pale green color and contains nickel as M, a=0, b=0.6, c= corresponds to 1,
It contained sodium as an exchangeable cation, and the cation exchange capacity was 72 meq/100g. The X-ray powder diffraction pattern is similar to the pattern of the inventive product in Example 1, and the d value of the (35,06) reflection peak is
It was 1.522 Å. The 2% aqueous dispersion formed a thixotropic pale green translucent solid gel.
The rheological properties of the 2.5% aqueous dispersion measured with a Fann VG meter were as follows: apparent viscosity (600 rpm)
= 8 cp, apparent viscosity (6 rpm) = 150 cp, plastic viscosity =
4cp, yield value = 7lb/100ft ² , gel strength after 10 seconds =
4lb/100ft ² and gel strength after 10 minutes = 32lb/100ft ²
It was hot. Example 4 The same procedure as in Example 1 was carried out except that the amount of raw materials charged was as follows. No. 3 water glass 86g Magnesium chloride hexahydrate first-class reagent 42g Zinc nitrate hexahydrate special-grade reagent (99% purity) 20g Lithium hydroxide monohydrate special-grade reagent 1.47g The obtained product was pure white and was designated as M. It contained zinc, corresponding to a = 4.05, b = 0.7, c = 0, contained sodium as an exchangeable cation, and had a cation exchange capacity of 80 meq/100g. The X-ray powder diffraction pattern is similar to the pattern of the inventive product in Example 1, and the d value of the (35,06) reflection peak is 1.523.
It was Å. The 2% aqueous dispersion formed a white translucent solid gel with thixotropic properties. Fann
The rheological properties of the 2.5% aqueous dispersion measured with a VG meter are as follows: Apparent viscosity (600 rpm) =
10cp, apparent viscosity (6rpm) = 150cp, plastic viscosity =
6cp, yield value = 7lb/100ft ² , gel strength after 10 seconds =
4lb/100ft ² and gel strength after 10 minutes = 41lb/100ft ²
It was hot. Example 5 The same procedure as in Example 1 was carried out except that the amount of raw materials charged was as follows. No. 3 water glass 86g Magnesium chloride hexahydrate first-class reagent 54g Ferrous hydroxide heptahydrate special-grade reagent (99% purity)
2.8g Lithium hydroxide monohydrate special grade reagent 1.47g The obtained product is white with a pale skin color, contains iron as M, corresponds to a = 5.2, b = 0.7, c = 0, and has good exchangeability. It contained sodium as a cation and had a cation exchange capacity of 98 meq/100g.
The X-ray powder diffraction pattern was similar to the pattern of the inventive product of Example 1, and the d value of the (35,06) reflection peak was 1.524 Å. The 2% aqueous dispersion formed a transparent solid gel with a thixotropic, slightly pale flesh color. Measured with Fann VG meter
The rheological properties of the 2.5% aqueous dispersion are as follows:
Apparent viscosity (600ppm) = 14cp, apparent viscosity (6ppm)
= 500cp, plastic viscosity = 7cp, yield value = 13lb/
100ft ² , gel strength after 10 seconds = 10lb/100ft ² and 10
Gel strength after minutes was 53 lb/100 ft ² . Example 6 The same procedure as in Example 1 was conducted except that the amount of raw materials charged was as follows. No. 3 water glass 86g Magnesium chloride hexahydrate first-class reagent 42g Cupric chloride dihydrate special-grade reagent (99% purity)
11.6g Lithium hydroxide monohydrate special grade reagent 1.47g The obtained product has a gray color and contains copper as M, corresponding to a=4.05, b=0.7, c=0, and sodium as an exchangeable cation. The cation exchange capacity was 76 meq/100g. The X-ray powder diffraction pattern is similar to the pattern of the inventive product in Example 1, and the d value of the (35,06) reflection peak is 1.518 Å.
It was hot. The rheological properties of the 2.5% aqueous dispersion measured with a Fann VG meter are as follows: apparent viscosity (600 ppm) = 14 cp, apparent viscosity (6 ppm) = 350 cp,
Plastic viscosity = 7cp, yield value = 13lb/100ft ² , gel strength after 10 seconds = 8lb/100ft ² and gel strength after 10 minutes =
It was 53lb/100ft ² .

Claims (1)

[Claims] 1 General formula [Si ₈ (M _6-ab Mg _a Li _b ) O ₂₀ (OH) _4-c F _c ] ^b-・A ^y+ _b/y (a, b, c in the formula and the value of y is 0≦a<
6,0<b≦2,0≦c≦4 and 1≦y≦2, M is Co, Ni, Zn, Cu, Fe, Mn, Pb, Cd
At least one divalent heavy metal ion selected from divalent heavy metal ions such as A is at least one cation selected from the group consisting of alkali metal ions, alkaline earth metal ions, ammonium ions, and alkylammonium ions. A synthetic swellable silicate with a structure similar to hectorite-type smectite. 2 General formula [Si ₈ (M _6-ab Mg _a Li _b ) O ₂₀ (OH) _4-c F _c ] ^b-・A ^y+ _b/y (The values of a, b, c and y in the formula are 0 ≦a<
6,0<b≦2,0≦c≦4 and 1≦y≦2, M is Co, Ni, Zn, Cu, Fe, Mn, Pb, Cd
At least one divalent heavy metal ion selected from divalent heavy metal ions such as A is at least one cation selected from the group consisting of alkali metal ions, alkaline earth metal ions, ammonium ions, and alkylammonium ions. In order to synthesize a synthetic swellable silicate having a structure similar to the hectorite-type smectite represented by
A homogeneous composite precipitate is prepared from a homogeneous mixture of divalent heavy metal salts and magnesium salts and an alkaline solution, and after removing by-product solutes, lithium ions and, if necessary, cations and fluorine, are added in an amount that satisfies the above composition. Synthetic swelling property represented by the general formula characterized by transferring the slurry obtained by adding ions to an autoclave, performing a hydrothermal reaction under conditions of 100°C to 350°C, and then drying and pulverizing the reaction product. Method for producing silicates.