JP5587938B2 - Composite clay composition - Google Patents

Description

  The present invention relates to a composite clay composition containing a smectite group clay mineral component.

  Smectite clay represented by acid clay and bentonite has long been used as an inorganic detergent because it has a high affinity for water and also exhibits a surface-active effect on oil. For example, Patent Document 1 proposes an inorganic detergent composition containing composite magnesium phyllosilicate and smectite group clay.

JP 2000-319690 A

However, smectite group clay minerals are generally produced with SiO ₂ crystals such as quartz, opal, cristobalite, and tridymite. In particular, opal and cristobalite that are intimately combined with smectite group clay minerals are considered to be extremely fine crystals of smectite. It is difficult to separate them together. Moreover, such a SiO ₂ crystal that is difficult to separate does not function as an active ingredient when the smectite clay is used for a cleaning agent or the like, and therefore, the smectite system containing a large amount of such SiO ₂ crystal. In order to obtain the desired cleaning effect, the clay has the disadvantage of having to use more than necessary.

Therefore, an object of the present invention is to provide a composite clay composition containing a smectite group clay mineral component in which SiO ₂ crystals of opal and cristobalite contained as inevitable impurities in smectite clays from many production areas are reduced. It is in.

According to the present invention, at 105 ° C. dry basis, (A) dioctahedral and smectite and (B) Synthesis of talc, (A) :( B) = 1: 2 to 1: it comprises 7 in a weight ratio of, 250 meters ² The X-ray diffraction peak derived from the [001] plane of smectite and the [001] plane of synthetic talc is substantially disappeared in the X-ray diffraction measurement, and the dioctahedral The diffraction peak of the [060] plane of the type smectite and the X-ray diffraction peak of the [060] plane of the trioctahedral type smectite are synthesized and expressed , and the [111] plane of the opal or cristobalite SiO ₂ crystal wherein the intensity of X-ray diffraction peak is smaller than the intensity of the synthesized peak by [020] plane and [020] plane of the synthetic talc smectite by Composite clay composition is provided.

In the composite clay composition of the present invention, it is preferable that the X-ray diffraction peak due to the [111] plane of the opal or cristobalite SiO ₂ crystal substantially disappears in the X-ray diffraction measurement.

  According to the present invention, natural smectite clay and magnesium oxide or magnesium hydroxide are mixed in the presence of water, and then heat-treated at a temperature of 60 ° C. or higher with stirring to produce talc. Furthermore, the manufacturing method of the composite clay composition which consists of a smectite group clay mineral and synthetic talc characterized by adding silicon dioxide and heat-processing at the temperature of 60 degreeC or more under stirring is provided.

In the production method of the present invention,
(1) The magnesium oxide or magnesium hydroxide is used in an amount of 1.5 times mol or more of the opal or cristobalite SiO ₂ crystal contained as an inevitable impurity in many smectite clays,
(2) using the silicon dioxide in an amount of 1.2 to 1.5 moles of magnesium hydroxide present in the system;
Is preferred.

In the composite clay composition of the present invention, SiO ₂ crystals such as opal or cristobalite, which are included as inevitable impurities that are difficult to separate in many naturally occurring smectite clays, are low crystalline synthetic talc (3MgO · 4SiO ₂ ) H ₂ O) is an important feature. That is, the SiO ₂ crystal that is difficult to separate from the smectite group clay mineral is a completely unnecessary component when the smectite group clay mineral is used for a detergent or the like, but in the present invention, this unnecessary component is low crystalline. In addition, this synthetic talc is excellent in affinity for oil. Therefore, according to the present invention, by converting SiO ₂ crystals, which are unnecessary impurities, to useful synthetic talc, it is possible to increase the surface activity effect of the smectite group clay mineral and increase its usefulness. It is.

In Example 1, it is a figure which shows the X-ray-diffraction pattern of the bentonite (a) of the natural smectite type clay used as a raw material, and the obtained composite clay composition (b). In Example 2, it is a figure which shows the X-ray-diffraction pattern of the acid clay (c) of the natural smectite type clay used as a raw material, and the obtained composite clay composition (d).

(Manufacture of composite clay composition)
In the present invention, natural smectite clay is used as a raw material. Examples of such smectite clay include those containing dioctahedral smectite as the main component (acid clay, bentonite) such as montmorillonite, beidellite and nontronite, and saponite. Typical examples include trioctahedral smectites such as hectorite and soconite. Bentonite, which is mainly composed of montmorillonite and beidellite, is naturally alkali-rich and can be used for various purposes as it is depending on the production area, and some alkalis are leached with rainwater. There are so-called active bentonites that have been treated to return to alkali rich using soda ash, etc., and it goes without saying that any of them can be used as the raw material of the present invention as a natural smectite clay. . Further, montmorillonite and beidellite are dioctahedral smectite has a layered structure consisting of SiO ₄ tetrahedral layers -AlO ₆ octahedral layer -SiO ₄ tetrahedra layer, a part of Al of these octahedral layer is Mg Ya Fe (II) has a basic skeleton in which a part of Si in the tetrahedral layer is replaced with Al by the same type of dissimilar metal as the lower valence metal, and the crystal lattice generates a negative charge at the substituted portion. However, there are balanced amounts of cations and water between these laminated layers, and they are neutralized in terms of charge. That is, smectite exhibits a cation exchange capacity according to the type and amount of such a substituted metal or interlayer element. Derived from the organic affinity and the polarity of the metal substitution site of the layer surface with such a layered structure of Si—O—Si bonds, it exhibits lipophilicity and hydrophilicity, and is a surface active effect suitable for applications such as detergents. It is thought that it shows.

As already mentioned, natural smectite clay is often produced together with SiO ₂ crystals such as opal and cristobalite, and depending on the production area, such a SiO ₂ crystal is a fine crystal having the aforementioned layer structure of smectite. It is difficult to separate by physical means such as wind. In the present invention, a natural smectite clay containing such difficult-to-separate SiO ₂ crystals can be used. In particular, the content of SiO ₂ crystals such as opal and cristobalite is 5% by weight or more, particularly 10%. It is preferable to use about 35% by weight. That is, this low SiO ₂ crystal content has a small merit for converting the SiO ₂ crystal into talc by the means described below. However, the originally low SiO ₂ crystal content is not so remarkable, but because of the high purity of smectite, it can be used more advantageously as a raw material for obtaining the composite clay composition of the present invention. it can. Therefore, for example, it goes without saying that the production method of the present invention can be carried out using a raw material whose intensity of the diffraction peak due to the [111] plane of SiO ₂ crystal is originally smaller than the diffraction peak due to the [020] plane of smectite. Yes. Further, those having a SiO ₂ crystal content larger than the above range often have high SiO ₂ crystallinity and low reactivity, and have a low smectite content, so that as a raw material for obtaining the desired composite clay composition Has little merit.

The SiO ₂ crystal content of opal, cristobalite, etc. contained in the smectite clay was dissolved in the alkaline aqueous solution by dissolving the SiO ₂ crystal by, for example, alkali treatment using an alkaline aqueous solution such as sodium hydroxide. It can be calculated as soluble silicic acid (%) by measuring the amount of SiO ₂ .

  The naturally occurring smectite clay used as described above exhibits, for example, the X-ray diffraction peak shown in FIG. That is, FIG. 1A is an X-ray diffraction chart of natural smectite clay (bentonite containing dioctahedral smectite as a main component) used as a raw material in Example 1 described later. As can be understood from this, this smectite clay exhibits a diffraction peak derived from the [001] plane of smectite in the region of 2θ = 5.0 to 8.0 °, and 2θ = 19.0 to 20.5 °. Shows a diffraction peak derived from the [020] plane of smectite, and further shows a diffraction peak derived from the [060] plane of dioctahedral smectite in the region of 2θ = 61.0 to 62.5 degrees. A diffraction peak derived from the [111] plane of opal or cristobalite is shown in the region of 2θ = 21.0 to 22.5 degrees.

In the present invention, the natural smectite clay as described above is reacted with magnesium oxide or magnesium hydroxide. Specifically, both are mixed in the presence of water and then heat-treated with stirring. As a result, the aforementioned opal and cristobalite SiO ₂ crystals contained in the smectite group clay mineral are converted into talc having a non-laminated or low laminated structure.

This reaction is represented by the following formula as an example. In the following formulae, the smectite group clay mineral is represented by Smectite, and the opal and cristobalite SiO ₂ crystals compounded thereto are represented by OpalSiO ₂ .
[Smectite + OpalSiO ₂ ] + 4.5MgO + 4.5H ₂ O
→ Smectite + SiO ₂ + 4.5Mg (OH) ₂
→ Smectite + 0.25 [3MgO.4SiO ₂ .H ₂ O] +3.75 Mg (OH) ₂

  In the above formula, magnesium oxide (MgO) is used as a raw material. However, since magnesium oxide is easily hydrated and changed to magnesium hydroxide in the presence of water, water is used as a reaction raw material from the beginning. Even when magnesium oxide is used, the reaction is expressed by the same formula.

As understood from the above reaction formula, the magnesium oxide (or magnesium hydroxide) to be used is preferably used in an amount of 1.5 times mol or more of SiO ₂ crystals contained in the smectite, and more than necessary. Since it is not meaningful even if used in excess, it is generally preferable to use it in an amount of 1.5 to 10 moles. In addition, when using magnesium oxide, it is a matter of course that equimolar or more of the magnesium oxide used, which is the theoretical amount of hydration with MgO, is necessary, but from the standpoint of wet stirring (slurry) reaction, reaction slurry In view of the fact that the viscosity is sufficiently fluid and is a solid-liquid reaction, the solid content concentration should be high to some extent, and should be 85 to 95% by weight based on the total amount of the reaction slurry mother liquor. Is preferred.

  Moreover, it is desirable that the natural smectite clay used in the above reaction is preliminarily pulverized and adjusted to an appropriate particle size. In this case, the raw material clay may be wet pulverized in an aqueous medium as it is, or may be dry pulverized after being dried once.

  In the above reaction, the heat treatment temperature is 60 ° C. or more, particularly 70 to 100 ° C., and the heat treatment time is generally about 3 to 8 hours, although it varies depending on the amount of smectite clay used and the heat treatment temperature. .

  In the present invention, after producing talc as described above, silicon dioxide is further added and heat-treated at a temperature of 60 ° C. or higher, particularly 70 to 100 ° C. with stirring. As a result, excess magnesium hydroxide remaining in the above reaction is also converted into talc and becomes an active ingredient.

The silicon dioxide used for such heat treatment is not particularly limited, but is preferably amorphous so-called white carbon from the viewpoint of not adversely affecting the properties of the composite clay even when an excessive amount of silicon dioxide remains. Used for. Such amorphous silicon dioxide (hydrous silicic acid) usually has the following formula:
SiO ₂ · nH ₂ O
In the formula, n is a number from 0.1 to 0.3.
It is represented by

Such a conversion reaction of magnesium hydroxide is represented by the following formula as an example.
Smectite + 0.25 [3MgO · 4SiO ₂ · H ₂ O]
+ 3.75Mg (OH) ₂ + 5SiO ₂ .nH ₂ O
→ Smectite + 1.5 [3MgO · 4SiO ₂ · H ₂ O]
However, n is the same number as the above.

  As understood from the above formula, silicon dioxide used in this example is 1.2 mol times or more of magnesium hydroxide contained in the reaction system (in terms of stoichiometry, 5 ÷ 3.75). = 1.33 mole times), especially 1.2 to 1.5 mole times converts the total amount of magnesium hydroxide produced to talc and the remaining silicon dioxide It is suitable for reducing the amount considerably.

  Such heat treatment for converting magnesium hydroxide into talc is usually performed for about 3 to 8 hours.

  The composite clay composition in which the SiO2 crystal contained in the smectite clay is converted into talc as described above is dried as necessary, classified into a predetermined particle size according to the use, and used.

(Composite clay composition)
The composite clay composition thus obtained is composed of (A) a smectite group clay mineral and (B) a synthetic talc [3MgO.4SiO ₂ .H ₂ O]. For example, FIG. 1 (b) or FIG. It has an X-ray diffraction peak as shown in d). FIG. 1B is an X-ray diffraction pattern of Example 1 and FIG. 2D is an X-ray diffraction pattern of the composite clay composition produced in Example 2.

  That is, as understood from FIG. 1 (b) or FIG. 2 (d), in such a composite clay composition, smectite [020] plane and synthetic talc are in the range of 2θ = 19.0 to 20.5 degrees. The diffraction peak derived from the [020] plane is synthesized and expressed (that is, the area is larger than the peak due to the [020] plane of smectite in FIG. 1 (a) or FIG. 2 (c)). The presence of smectite and synthesized talc is confirmed, but the diffraction peak derived from the [001] plane of smectite that should originally exist in the region of 2θ = 5.0 to 8.0 degrees, and 2θ = 9. The diffraction peak derived from the [001] plane of the synthetic talc that should exist in the region of 0 to 10.0 degrees is substantially absent or not observed. That is, in the composite clay composition of the present invention, the smectite in the water-dispersed state and the newly generated synthetic talc particles are mixed at the monolayer particle level by the semi-synthetic reaction under hydrothermal treatment performed in the two steps described above. Even when dried, smectite and talc do not stack in the C-axis direction, or even if they occur, it seems to be disordered stacking with irregular layer spacing, and diffraction peaks appear in these regions. The fact that the composite clay composition of the present invention is different from a simple mixture of smectite group clay mineral laminated particles and talc laminated particles shows that both are randomly and uniformly compounded.

In the composite clay composition of the present invention, the SiO ₂ crystals of opal and cristobalite contained as inevitable impurities in smectite clay from many production areas are converted to talc. Therefore, as can be understood from the comparison of the X-ray diffraction peaks of FIGS. 1 (a) and 1 (b) or FIGS. 2 (c) and 2 (d), 2θ = 21.0 to 22.2. The diffraction peak due to the [111] plane of the SiO ₂ crystal seen in the 5 ° region (see FIGS. 1 (a) and 2 (c)) is substantially disappeared or reduced in this composite clay composition. (See FIGS. 1B and 2D). That is, loss or reduction of the diffraction peaks due to [111] plane of such SiO ₂ crystals, all or most of the SiO ₂ crystals such smectite clay minerals are telling that it is converted to talc.

As can be understood from FIG. 1 (a) or FIG. 2 (c), the smectite clay used as a raw material in the present invention has a diffraction peak (2θ = 21.0) on the [111] plane of the SiO ₂ crystal. to 22.5 degrees), but is often greater than the diffraction peak of [020] plane of the smectite (2 [Theta] = 19.0 to 20.5 degrees), the composite clay composition of the present invention, such SiO ₂ crystals The diffraction peak of the [111] plane is smaller than the combined peak (2θ = 19.0 to 20.5 degrees) of the smectite [020] plane and the synthetic talc [020] plane as described above. If synthetic talc is formed by heat treatment, desired effects such as improvement of the surface active effect can be ensured.

  In the present invention, when dioctahedral smectite such as bentonite or acid clay is used as the smectite clay, as shown in FIG. 1 (b) or FIG. 2 (d), 2θ = 59. The X-ray diffraction peak (2θ = 61.0 to 62.5 degrees) of the dioctahedral clay mineral in the region of 5 to 62.5 degrees and the [060] plane of the trioctahedral clay mineral It is confirmed that the X-ray diffraction peak and (2θ = 59.5 to 61.5 °) are synthesized and expressed. That is, the expression of such a synthetic peak indicates that a low-layer synthetic talc, which is a trioctahedral three-layered clay mineral, is generated by the semi-synthetic reaction under the hydrothermal treatment in the two steps described above. Show.

In the present invention, the composite clay composition having the above-described structure generally comprises (A) smectite group clay mineral and (B) synthetic talc on the basis of drying at 105 ° C. (A) :( B) = 1: 2. To 1: 7 by weight, and since it contains a smectite group clay mineral and synthetic talc in such a balance, it exhibits physical properties (surfactant action) peculiar to smectite and at the same time synthetic talc. Combined with the lipophilicity and oil-absorbing properties of oil, the cleaning action by absorption, adsorption and emulsification dispersion of oily substances is enhanced.

Also, the composite clay composition of the present invention is produced by converting the opal or cristobalite SiO ₂ crystal, which is intimately combined with the ultrafine crystal of smectite, into a synthetic talc of ultrafine crystal, and further, the smectite And each fine crystal of synthetic talc is randomly dispersed, and even if it is concentrated or dried and solidified, each fine crystal does not cause further lamination, or even if it occurs, it becomes irregular and disordered laminated particles Therefore, for example, it has a considerably higher specific surface area than a simple mixture of raw smectite clay and natural talc. The BET specific surface area of the mere mixture is 100 m ² / g or less, whereas the composite clay composition of the present invention is usually 250 m ² / g or more, particularly about 250 to 500 m ² / g. high.

Furthermore, since the composite clay composition of the present invention is converted to talc of SiO ₂ crystals by hydrothermal treatment to such an extent that the basic structure of the smectite group clay mineral is not impaired, the cation exchange ability derived from smectite and In addition to maintaining the properties as a solid acid, it has a large amount of solid acid with relatively weak acid strength derived from newly generated synthetic talc. For example, the composite clay composition has a cation exchange capacity of 5 meq / 100 g or more, particularly 10 to 50 meq / 100 g. Further, in the surface acidity distribution measured by the n-butylamine titration method, the acid strength function Ho is larger than −3.0 (indicator: dicinnamalacetone) and not more than +3.3 (indicator: p-dimethylaminoazobenzene). There are many acid points of moderate strength (-3.0 <Ho ≦ + 3.3) and relatively weak acid points in the acid strength region of +3.3 <Ho ≦ + 4.8 (indicator: methyl red). Existing. Since the acid amount (meq / g) of these solid acids varies depending on the type of smectite in the composite clay composition, the type of interlayer ions, the content ratio of smectite and synthetic talc, etc., it cannot be said unconditionally. The total acid amount is 0.5 meq / g or more, and in particular, some compositions have a large volume of solid acid of 1 meq / g or more.

  In addition, since the clay composition of the present invention has both a cation exchange ability and a solid acid as described above, and has a high specific surface area, a basic dye having a relatively large molecule such as methylene blue is also adsorbed well.

  As described above, the composite clay composition of the present invention has a large specific surface area, exhibits a cation exchange characteristic peculiar to smectite, and absorbs and adsorbs oily substances and smectite due to an increase in lipophilicity due to the formation of talc. It is used in various applications because it has a high cleaning effect due to its surface active action (emulsifying and dispersing action) and exhibits properties as a solid acid by both smectite and synthetic talc. For example, as an oily substance absorption / adsorption agent, kitchen oil stain cleaner, cleanser around kitchen range and frying pan, hand cleaner, hair cleaner, toothpaste, pet shampoo, outdoor oil stain cleaner, It can be used as a detergent builder for kitchens, a detergent builder for clothes, a detergent builder for automatic dishwashers, a stain re-adhesion inhibitor for ultrasonic automatic washing machines, and a pitch adsorbent for papermaking. Moreover, it can also be used for uses, such as an activated clay substitute and a solid acid catalyst, as a high specific surface area adsorption agent which has moderate solid acid.

The superior effect of the present invention is illustrated in the following examples.
In addition, the various tests in an Example were done with the following method.
(1) X-ray diffraction Sample preparation:
The powder sample is left as it is, and for the slurry sample, the wet cake obtained by suction filtration is dried at 110 ° C. and then pulverized in a mortar to obtain a measurement sample.
X-ray diffractometer: Rigaku Co., Ltd., MultiFlex
Measurement conditions: X-ray = Cu-Kα ray, tube voltage = 40 kV, tube current = 30 mA, diverging slit:
0.15 mm, scattering slit: 1 °, light receiving slit = 0.15 mm
Scanning range: diffraction angle (2θ) = 3 ° to 70 °

(2) Soluble Silicic Acid 150 g of a sample dried at 110 ° C. is dispersed in 450 g of pure water, 53.3 g of sodium hydroxide (NaOH) is added, and the mixture is heated and stirred at 100 ° C. for 5 hours. Allow to cool and measure the total weight of the dissolved reaction solution. The dissolved mother liquor is allowed to stand for 1 day or longer to allow the solid content to settle, and a transparent supernatant is collected to quantify the SiO ₂ concentration in the solution portion. The amount of SiO ₂ eluted from 100 g of the sample is obtained by calculation and used as the soluble silicic acid (%) in the sample.

(3) BET specific surface area Measured using an automatic specific surface area measuring device (TriStar 3000, measuring method: gas adsorption method by a constant volume method) manufactured by Micromeritec.
The multipoint specific surface area by the BET method is determined from the adsorption isotherm of nitrogen gas.

(4) Oil absorption sample preparation:
In any of the slurry-like or paste-like sample and the powder-like sample, water is added to adjust the solid content concentration to 5% by weight to obtain a fluid suspension, which is used as a test sample.
Oil absorption test:
Take 20 g of the test suspension in a glass sample tube with a screw cap (internal volume: 50 mL), add 0.5 g of commercially available edible oil (oiled) using a Komagome pipette (for 1 mL), then cover Shake well the sample tube until the entire contents are emulsified. The obtained emulsified liquid is immediately taken into another clean Komagome pipette (for 1 mL), and 2 drops thereof are placed on one place on the qualitative filter paper (No. 2). When the nearly circular suspension generated by dripping is air-dried, the oil that could not be absorbed has oozed out into the filter paper around the circular thin flat trapezoidal mass made of the solid content of the suspension. The presence or absence of a translucent halo (ring) is confirmed by visual observation.
Judgment display:
○ ... Translucent halo (ring) due to oil oozing that could not be absorbed completely
It is hardly observed, and all or most of the oil is absorbed by the solid content in the suspension.
It is fixed.
× ... Translucent halo-like ring due to exudation of oil that could not be absorbed clearly
Observed and absorbed only in almost or small amounts (<< 25 mg [oil] / g [5% suspension])
・ It is not fixed.

(5) Solid acid sample preparation:
The powder sample is left as it is, and for the slurry sample, the wet cake obtained by suction filtration is dried at 110 ° C. and then pulverized in a mortar to form a test sample.
Surface acidity test:
Take 0.1 g of the test powder sample in a test tube (inner diameter: 15 mm), dry at 150 ° C. for 2 hours, and then add 2 mL of cyclohexane (dehydration, reagent) and 1 mL of 0.05M n-butylamine (cyclohexane solution) sequentially. And shake. Add 3 drops of methyl red saturated solution (less than 0.1 [w / v]%) of acid / base indicator to determine whether the color is acidic (pink) or basic (yellow), The acid point of the intensity range [Ho ≦ + 4.8] represented by the acid strength function Ho corresponding to the logarithm of the reciprocal of the acid dissociation constant of the conjugate acid of the indicator (pKa = + 4.8) is 0.5 meq / g or more. It is determined whether or not it has.
Judgment display:
○ ... Remains even after neutralization with 0.5 mmol of n-butylamine per gram of sample.
Less acid in the intensity range [Ho ≦ + 4.8] that causes methyl red to become acidic
Both have 0.5 meq / g or more.
× ... When neutralized with 0.5 mmol of n-butylamine per gram of sample, the indicator methyl
Acid that causes red to have an acidic color does not remain, and an acid in the intensity range [Ho ≦ + 4.8]
The acid amount is less than 0.5 meq / g.

(6) Methylene blue adsorption Sample preparation:
The powder sample is left as it is, and for the slurry sample, the wet cake obtained by suction filtration is dried at 110 ° C. and then pulverized in a mortar to form a test sample.
Methylene blue adsorption test:
Take 0.1 g of the test powder (dry matter equivalent) in a polypropylene centrifuge tube with a screw cap (internal volume: 15 mL), and add 5 mL of water (ion-exchanged water) and 1 mL of 0.01 M methylene blue aqueous solution sequentially. Shake and adsorb, then centrifuge to separate solid and liquid. About 2 mL of the supernatant is gently sucked with a Komagome pipette and transferred to a test tube to determine whether the methylene blue aqueous solution is colored blue to light blue, and has a methylene blue adsorption capacity of 0.1 mmol / g or more. Judge whether or not.
Judgment display:
○ When 0.1 mmol of methylene blue is adsorbed per 1 g of sample, the total amount is tested.
Adsorbed by the material, the solution part becomes almost colorless and transparent, at least 0.1 mmol /
It has a methylene blue adsorption capacity of g or more.
X: When 0.1 mmol of methylene blue is adsorbed per 1 g of sample, the total amount is absorbed.
The solution part is blue or light blue with the remaining methylene blue.
Has little or no renblue adsorptive capacity or less than 0.1 mmol / g
Adsorption capacity.

Example 1
As a natural smectite clay, activated bentonite (hereinafter simply referred to as bentonite) produced by activating sub-bentonite from the A district of Shibata City, Niigata Prefecture by sodium carbonate treatment by a conventional method, drying and grinding, is used as a raw material. It was.
<First stage reaction>
Stainless steel tank filled with about 1 kg of 215 g (Smectite: 140 g, opalSiO ₂ : 60 g) of raw material bentonite powder (adhesion moisture: 6.8%, dry matter standard ⇒ Smectite: 70%, opalSiO ₂ : 30%) (Internal volume: 11 L) In addition, with stirring, commercially available magnesium hydroxide powder as a first stage reaction raw material (adhesion moisture: 1.6%, dry matter basis ⇒ MgO: 67%) 273 g (MgO: 180 g) The mixture is made into a mixed slurry, heated with stirring and heated to 95 ° C for 8 hours, and the reaction is continued for 8 hours. Therefore, an appropriate amount of additional water was added twice.). At this time, the crystal opal-like silica almost disappeared by XRD measurement, and a large amount of unreacted magnesium hydroxide was confirmed.
<Second stage reaction>
Next, commercially available white carbon (as a raw material for the conversion reaction (second stage reaction) of unreacted magnesium hydroxide (MgO conversion: 150 g) remaining after being added in large excess (six times the theoretical reaction amount) to talc ( Moisture adhering: 6.7%, dry matter standard ⇒ SiO ₂ : 95%) 338 g (SiO ₂ : 300 g = theoretical reaction amount) was added, and the reaction was continued at 95 ° C. for 10 hours in the same manner as the first stage reaction. finished.
Various test results on the obtained slurry (solid content concentration: 11.9%, pH: 8.7) are shown in Table 1.

(Example 2)
As a natural smectite clay, acid clay was used as a raw material, which was made by drying and pulverizing clay from Shibata City B, Niigata Prefecture.
Made of stainless steel with about 1 kg of water of 222 g (Smectite: 140 g, opalSiO ₂ : 60 g) of the raw acid clay powder (adhesion moisture: 9.9%, dry matter standard ⇒ Smectite: 70%, opalSiO ₂ : 30%) In addition to the tank (internal volume: 11 L), under stirring, commercially available magnesium hydroxide powder as the first stage reaction raw material (adhesion moisture: 2.2%, dry matter basis ⇒ MgO: 67%) 69 g (MgO: 45 g ) Is added to form a mixed slurry, and the temperature is raised while stirring, and the reaction is continued at 95 ° C. for 12 hours (during the reaction, the viscosity of the slurry increases due to the progress of the reaction or evaporation of water due to heating, which hinders stirring) Since it occurred, an appropriate amount of water was added three times.) At this time, the crystal opal-like silica disappeared by about 90% by XRD measurement, and the presence of unreacted magnesium hydroxide was slightly observed. Next, as a raw material for the conversion reaction (second stage reaction) of unreacted magnesium hydroxide (MgO conversion: 15 g = theoretical residual amount) remaining after being added in excess (1.5 times the theoretical reaction amount) to talc commercially available white carbon (water attached: 6.9%, dry basis _{⇒SiO 2: 95%) 34g (} SiO 2: 30g = theoretical reaction volume) was added, as in the first stage reaction, 10 hours at 95 ° C. The reaction was continued and finished.
Various test results for the obtained slurry (solid content concentration: 24.3%, pH: 7.9) are shown in Table 1.

(Reference Examples 1-3)
Bentonite (Reference Example 1) and acid clay (Reference Example 2), which are raw materials for the first stage reaction of each of (Example 1) and (Example 2), and white carbon which is a common raw material for the second stage reaction (Reference Example 1) Various test results for the powder of Reference Example 3) are shown in Table 1.

Claims (2)

BET ratio of 250 m ² / g or more , containing (A) dioctahedral smectite and (B) synthetic talc in a weight ratio of (A) :( B) = 1: 2 to 1: 7 on a dry basis of 105 ° C. In the X-ray diffraction measurement, the X-ray diffraction peak derived from the [001] plane of smectite and the [001] plane of synthetic talc is substantially lost, and [060] of dioctahedral smectite The surface diffraction peak and the X-ray diffraction peak of the [060] plane of trioctahedral smectite are synthesized and expressed , and the X-ray diffraction peak of the [111] plane of the opal or cristobalite SiO ₂ crystal Composite clay composition characterized in that the strength is smaller than the strength of the synthetic peak due to the [020] face of smectite and the [020] face of synthetic talc. object. _2. The composite clay composition according to claim 1, wherein, in the X-ray diffraction measurement, the X-ray diffraction peak due to the [111] plane of the opal or cristobalite SiO ₂ crystal has substantially disappeared.

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